Kite Strings

Jim Rooney - 2009/11/03 06:16:56 UTC

God I love the ignore list

Lauren Tjaden - 2005/03/05 00:37:37 UTC

Today I experienced a lovely flight, a little 40 minute number to 3100, flown after 3 PM, when the thermals had lost some of their sharp edges. I was brave enough and smart enough not to run when other pilots came in on my tail. Once I got scared enough I let another pilot take my thermal, but I at least stayed on the outside of the circle and came back in after he got higher than I was, instead of punishing myself by marching off to another area in a huff. When it's blue, you gotta give up your pride! Actually I am just learning a bit about how to fly politely in company.

Landing was interesting with many pilots plummeting from the sky at the same moment, complicated by a small, tempting -- but ultimately unworkable -- thermal, 3-4 hundred feet over the LZ. Ah, that is what the tug plane is for; you can always try again if it is too challenging and you are in danger pushing it.

After landing, it was time to confront my third challenge for the last two weeks. The challenges were: (number 1) I had to go XC at least once, (number 2) try to get my 4, and (number 3, the one that I hadn't done) tow off my shoulders. It is amazing what a woosie I am. Worry worry worry but I was damned if I was going to put it off.

Zach (Woodall) and Paul explained that I couldn't jam the bar out in front of me like I do when I launch regularly; that I might pop up and stall my glider (and fall to the ground and writhe in pain and then die), but that I must allow myself to be pulled though the control frame a bit and then hold my arms rigid.

Zach kept saying, no, more forward, no, more than that, when I asked if my body was forward enough. Finally I just said, OK, I am launching. He said later my pitch was perfect but I was petrified for a couple of seconds wondering if I got it right.

The tow was uneventful but the bar pressure was lots more, and I already fly with half VG so I don't feel I can increase it. It was harder to follow the plane when I got high on it. Zach pointed out later I could just stay a little low. Actually I think it will be fine since I am strong, but it will be more difficult to tow in midday conditions, because of the bar pressure. But I sure liked the clean configuration and it is much less drag. Really so much less crap hanging off my down tube.

So Paul just told me he has 3 more goals for my next 2 weeks. COOL! It is very constructive for me to have these things to aim for.

Come see us soon.

Love
Lauren

Hugh McElrath - 2005/03/05 02:24:13 UTC

Lauren,
I just read something in the USHGA mag about towing configurations and they mentioned greater risk of a lockout when towing from the shoulders. What do the folks down there say?

Lauren Tjaden - 2005/03/05 13:25:42 UTC

My understand is that since all the tow forces are on you (when towing from the shoulders), not you and your glider combined, that in a lockout it might be more difficult to recover since your shoulders will be pulled in the direction of the plane more strongly (someone please correct me if I am wrong, since I have limited experience with this, to say the least). Also, the bar position is further back so you have less leverage to push it back into position than if it was further ahead of you.

On the plus side, you?have less drag and less hassle in the air stowing your tow bridle.

I also feel it may be easier to pin off in case of a lockout because you have a bailey (for me, two of them, one on each side) and they are much closer to your center of gravity. Reaching that handle way out to the side can be challenging in a hard turn. The bailey is right there.

I would welcome hearing more expert opinions, as well.

Hugh McElrath - 2005/03/05 16:10:16 UTC

Hmmm... thanks for the thoughtful reply. Since I don't use a bicycle brake handle but a loop around my palm, I have even less problem pinning off than with a bailey (which I have for backup). That may actually be the tie-breaker for me: right now, I can pin off without removing my hand from its position on the base tube. Towing from the shoulders I would have to find one of two bailey's possibly with a gloved hand (have to look down with the chin guard of my helmet in the way, too). Roger the hassle of retrieving the tow bridle and the drag of the release. Decisions, decisions...

Tad Eareckson - 2005/03/05 16:44:12 UTC

Damn, Hugh stole a lot of my thunder before I could post but...

The two point release I developed the better part of four years ago blows you off tow with stored energy, is actuated with minimal force by sliding your hand inboard along the basetube a couple of inches, and is lighter and magnitudes cleaner than any other two point system out there. It restores virtually all of the full point of performance that Rob Kells estimates the external cable housing crap sucks out of your faired downtube and the transmission element can't bind in such housing. It is also, as far as anyone has yet been able to determine, one hundred percent reliable.

Yeah, the modern crop of fast, low pitch pressure gliders makes the one point/shoulders only/pro tow option very attractive and it's nice not having to reel in and stuff all that trailing bridle upon getting to altitude. I use and feel reasonably comfortable with it myself when taking demo hops - especially after getting the first hundred feet below me.

And the aerotow launch itself seems to have proved itself so insanely safe that I was starting to think that maybe things weren't all that critical until someone provided a lot of evidence to the contrary last summer.

The more difficult it is to effect a release the more people are gonna die.

Attention Eagle people:

If you're willing to invest in a couple of extra zipper pulls you don't have to leave your sail unzipped.

Hugh McElrath - 2005/03/05 17:02:56 UTC

Thanks, Tad. I was too green to fully appreciate your system when you showed it to me a couple of years ago. Now I'm more interested. Do I have to fabricate this myself from parts or are you in business?

Brian Vant-Hull - 2005/03/05 17:11:22 UTC

You have the secondary release in conventional towing anyway (yes, I've used it), and not that much more to stow, though I may be wrong. I guess for competition you may worry about a little extra drag, but otherwise why bother with the extra safety issues?

Paul Adamez - 2005/03/05 18:20:47 UTC

My biggest concern with the V bridle is if my Spinniker release fails and I use my secondary and the bridle gets hung up on the caribiner on the end of the tow line. Now I am being towed straight from the hang loops, or keel, with no way of releasing, in a very bad tow configuration. Not good.

I've been giving thought about going with the Pro Tow, especially with all the discussion on the OZ Report, but am concerned too about any increased lock out tendencies with this method. With the Pro Tow I may be more apt to release sooner if I get too out of wack and not try to wrestle with the situation, which may be a good thing.

Tad Eareckson - 2005/03/06 19:33:17 UTC

Oh joy of joys! Finally the prospect of doubling the population of this system.

Yeah, I welcome with open arms anyone - individual, park, manufacturer - to plagiarize this rig and keep all that R&D from going the way of Beta tape and, yeah, I'd be happy to be in the business if anyone would rather avoid the hassle him-/herself.

I have extensive documentation on components, loads, and specs and have written (and several times rewritten) an article. Kolie and Pauls Adamez and Gerhardt have been very kind to do some photo shoots but I keep finding things I should have set up better and really ought to go out with a tripod and sacrifice part of a day before going to press.

Re the first Paul's concerns...

The spinnaker shackle doesn't fail in its function. If a reasonable pull is applied to the spring loaded latch the gate opens. (Caveat - I have found that a hang up of the weak link on the notch at the gate may occur upon a low tension release but it doesn't last long after a little tension is restored.) It's the activation and transmission elements that fail. Problems I've seen and/or had reported include improper adjustment of cable play, insufficient throw capability of the mounted brake lever assembly, and binding of cable and housing (the sort of problem that used to render a lot of ballistic parachutes inert). Although the loop activated flavor appears to be a pretty reasonable second-best, Sunny related that Highland has seen so many failures that they no longer sell them (your mileage may vary).

The leech line based transmission, evolutionary variations of which I've been using since 1994, does not fail and is extremely efficient in delivering the force to where it's needed.

Yeah, the scenario Paul described involving a two point system in which the primary fails and the bridle wraps could be a real nightmare - especially if the trim point is way forward on your keel (like mine). There was a group of tow pilots who hadn't thought things through more than the initial step members of which were deliberately releasing at the bottom end of the bridle so that it would stream better out of the way during free flight. When step two chanced along one of them had his glider fail under negative loading and was lucky to just get majorly injured.

But in the course of conventional setups and operation this, statistically, just isn't on the screen - especially if you're using proper equipment and technique.

Bridle wraps are rare and almost nonexistent if:
- the ends are cleanly spliced or tapered and it's of a fairly stiff, inelastic, and substantial material
- weak links aren't stupidly long
- releases are initiated under low tension

The wisdom I scored from Sunny regarding the last point is... At wave off, climb, dive to slacken the tow line, and release. The tow ring (carabiner) slowly falls away while the bridle gently feeds through it. (Also eliminates that annoying stall one experiences otherwise and the shackle doesn't hammer itself.)

Further along - let's make this a worst case lockout scenario - there's a weak link at the top of the bridle which will now be experiencing something along the lines of a double load and a tug driver with a lever on that end which may do you some good.

And, again, the technology has existed for over a decade such that no one should even be worrying about a primary release failure.

And there's very little reason that we should have to let go of the steering wheel to try grab something at a bad time either.

I also note in the 2005/02/21 installment of the Oz Report a reference to failure of the secondary bridle to feed through the end of the primary after a wrap. I've been using a painfully obvious remedy to that problem - which also prevents those components of your equipment from sawing each other apart - for over a decade as well. It involves a stainless steel sail thimble.

Hugh McElrath - 2005/03/06 23:02:06 UTC

OK, Tad, you've blown me away with too much information - but the part about loop-type releases having a higher failure rate sure got my attention. What is the failure mode? Won't release or release uncommanded? I've had the latter, just learned to make damn sure the shackle is all the way on the gate. Let's get together at Ridgely or in town and work on replicating your rig - or making a Mark II...

Brian Vant-Hull - 2005/03/06 23:35:59 UTC

I believe the problem is not with the method of pulling the release, but the way the gate itself was configured with these models - the tow line would end up pulling on the hinge and there was thus no force to pull the gate open. There's a couple of ways to mitigate this problem by changing the way the gate is suspended, but the problem is *not* with the loop pull itself.

There's a line that connects the gate to the glider. If this line attaches exactly opposite to the hinge, there's a good chance the tow line will naturally pull against the hinge. If this is happening it's imperative to reroute the attachment line.

I had problems with my pull loop release until I had the attachment line rerouted. At some point Ralph flew my glider and was scared silly when it didn't release, but unfortunately I don't remember if this was before or after I rerouted the line.

There may have been other problems associated with not having extra force from the lever effect of the bicycle release. Sunny or Adam may know.

Tad Eareckson - 2005/03/07 14:15:12 UTC

You really didn't expect me to shut up after a paragraph or two, did ya?

Release uncommanded is an annoyance, won't release is the potentially deadly problem that puts the loop style on the Banned In Ridgely list. The complaint I heard from Sunny was that the shackle wasn't opening. The problem that you (Hugh) described in the former category is a byproduct of both styles and another issue which disappears with a leech line setup.

With that detail on the checklist, I wouldn't sweat your copy - if it works, it works. I kinda like it when stood alongside the bicycle brake jobs. Checked one out as thoroughly as I could on the ground and the best I could speculate was that the cable will, by definition, be subjected to two changes in direction and the resulting binding resistance. Its counterpart often gets away with one turn and, as Brian says, benefits from something on the order of a four to one force magnification courtesy of the lever mechanical advantage.

I can, however, with a little effort imagine scenarios in which the loop contributes to a control problem or broken wrist.

I've long been puzzled by reports of gates failing to open after the latch has cleared (e.g. Ralph's 2000/08/26 malfunction (yes, prior to modification)). The hypothesis is that our weak links, with their diameters magnitudes smaller than the lines for which the Wichard Quick Release Shackle 2673 was designed, focus their tension force directly on the center of the pivot point and there isn't enough offset to start to swing the gate.

I've never been able to duplicate this failure on the ground (or in the air). If I pull a loop of 130 pound braided Dacron directly in line it opens. If I immobilize the shackle upside down (gate up), cram a loop of dental floss inside the pivot cutout on both sides of the gate end, and pull the line aft 140 degrees and parallel to the fixed arm... it opens - easily and immediately.

A couple of seasons ago Les Taff informed me that the offset drilling mutilation one often sees is not perpetrated to accommodate opening but to keep the weak link from getting chewed up by the couple of sharp edges of the pivot cutout. Apparently some copies are more problematic than others - I've never had a problem with the ones I've used. And if I did I'd address the issue with a file.

Another idea with respect to Paul's double failure scenario. In the event of a primary malfunction under best case scenario options (i.e., at wave off) I might give a thought to diving then pushing out and rolling (to minimize the danger of the resulting stall) to try to pop the weak link before I started using up other options. Opinions?

I don't have any great Mark II concepts. After release I'd like to rid myself of about eight inches of taut leech line standing up against the breeze but the last few years of thinking about it haven't yielded anything very worthwhile.

I took a look at some U2 (right?) diagrams and the basetube looks like it would be easy to work with.

Brian Vant-Hull - 2005/03/07 14:33:14 UTC

I don't know where "banned from Ridgely" comes from, since several of us have been using the pull loop system for years. After I rerouted the attachment line I never had another release problem, and that was years ago. I can understand they wouldn't sell them - though I think with modification they are fine (preferable in my book for instant pull access).

I rather like the "drilling mutilation" solution: the attachment line rerouting is a little too subtle for my taste, but I don't have the tools or perhaps even the skill to drill through a small section of curved metal without the bit skating all over. Someday I'll probably have it done.

Tad Eareckson - 2005/03/08 00:00:06 UTC

Naw, the "Banned In Ridgely" comment was just a reiteration of my earlier mention that it's no longer available at the counter. And, yeah, it's next in my preference line below what I have and above the brake lever. If one is accepting the aerodynamic penalties of a two point system anyway I think it's nuts not to have the option of having a finger on the trigger when the cart starts to roll. If the cable routing turn radii are sufficient and the bottom end of the housing is properly secured I don't see a problem.

Although there doesn't seem to be any data to back up my paranoia I keep envisioning the downstream end of the latter mechanism protruding from an eye socket. Also seems like somebody is eventually gonna find a way to snag something real important. And it doesn't exactly scream "streamlining".

I must part paths with you on my feelings about the drilling however - I really, really hate it. Rotates the load 90 degrees from the way it was designed to operate and dumps it all on the latch which wasn't envisioned to take anything. And I'm wondering if it might have an adverse enough effect on required trigger tension that you really need that brake lever mechanical advantage at the upper range of things.

Before doing anything irreversible allow me to run a tensioner between the fixed arm of the shackle and the glider's nose. If your attachment line rerouting is addressing any problems, I believe the tensioner will do it better and bestow a couple of other advantages as well.

Also, although, as I said, I've never had a problem, I just took a couple of small files to a couple of spinnaker shackles and rounded out some sharp edges around the pivot cutout and hinge pin riveted faces. It took a few minutes and reduced the threat level to the weak link from no way to no freakin' way - without marring the finish of those beautiful pieces of hardware. Possibly more labor intensive than clamping one under a drill press but not much and with infinitely more satisfactory results.

Hugh McElrath - 2005/03/08 00:57:50 UTC

Duh... I've never thought of doing maneuvers before releasing - just keep flying straight and level and pop the release. I don't normally stall - just keep the nose at the same AOA (don't let it pop up) and enjoy the relaxation of letting the glider fly at its own speed instead of being dragged faster than it wants to go.

Jim Rooney - 2005/03/08 03:41:20 UTC

There's a bit of a distinction to note here. One that is not mentioned in the USHGA article.

There are two ways to use a 3 point towing system. The top towpoint can either be on the keel or on your carabiner. The differnece between these is important.

The method described in the magazine is a keel mount. Since the tow forces act both on the CG and the glider, your gliders nose gets pulled through turns. You can also reduce pitch preassure by moving the tow point further up the keel.

Towing off the carabiner is very different in that all tow forces act on the CG. The important distinction here is that it will "feel" like towing off the keel, but it acts like towing off the shoulders.

It feels like towing off the keel because your bar position is similar and the tow force is split between you and your hang strap. This is different from keel towing since the other half of that tow force is not acting on the glider.

The comment in the magazine is that the pro tow method makes lockouts harder to correct. This is in no small part due to the tow forces in a keel tow setup are trying to pull your nose out of a lockout.

This is not true in a carabiner tow setup.

The difference between the carabiner tow and a two point shoulder tow is that the tow force is no longer split. You get it all. This changes your bar position and you feel all the tow force. This is not pitch preassure, just pulling preassure. The difference in how your glider flies is none. All tow forces are still routed through the CG.

Something of note between the keel tow and carabiner tow... in the rare event of becoming stuck on the top towpoint only (primary fails to release, secondary releases the shoulders but not the bridal), the carabiner tow will still be pulling of the CG if you're towing off the carabiner, the keel tow will be trying to tumble you.

In the end, it's all a matter of tradeoffs. None of the systems are failsafe and each has its stronger and weaker points.

$.02USD

Tad Eareckson - 2005/03/08 12:56:13 UTC

I would strongly recommend the climb, dive, release procedure at all waves off.

There's nothing that pops the nose up at release - it's been popped since you left the cart. That may not be real apparent on the glider you're driving but take a side view of a tug with glider in tow next time you're sinking past such a combination.

If you release under tension the AOA changes instantly - and your pitch attitude has to be reduced to regain it. Either you pull in or do nothing and wait for the glider to work on the problem.

"Popping the release" subjects the spinnaker shackle to a bit of abuse and the bridle to a little extra friction and wear but also sends the bridle, which is supposed to keep going up with you, whipping towards equipment which is about to descend with somebody else.

Give the gentle option a try - it's pretty neat watching the slow feed through the floating carabiner. And I would be amazed if a wrap ever developed when the tow line is slackened.

Steve Kinsley - 2005/03/11 02:43:09 UTC

Winter boredom and the Oz report resulted in my invention of "the squid"AT shoulder release. This is a two ring (or 3 -- haven't decided which is better) where the final loop runs thru a grommet and you hold it in your teeth. Want off? Open your mouth. When you are 100 ft up and presumably out of danger you slide a barrel (the body of the squid) over the loop which crimps it at the grommet and you have a standard barrel release. I can hold on with my teeth all the way and not use the slider/keeper but gotta be sure I have fresh polident.

Tried it at Manquin and down in Fla. Seems to work fine. (flew with a standard barrel on the other side just in case) Also gets a lot of laughs. Show it to you.

Scott Wilkinson - 2005/08/25 13:18:56 UTC

Being a new AT pilot who hasn't experienced a weak link break yet...I'm curious about what types of scenarios can cause this? Obviously a lockout can cause one...but I'm wondering more about breaks right off the cart. This seems to happen a lot (maybe not?) and I don't understand how/why?

Any illumination is appreciated!

Matthew Graham - 2005/08/25 13:29:58 UTC

Talk to the sailplane people about this. They have scenarios for what to do if a weak link breaks at various altitudes. I've never seen anything taught on this subject at any of the tow parks. They might. I just haven't seen it. Anyway, you should have a plan of action for a weak link break:

on the cart
just after coming out of the cart
at an altitude of up to 30
from 30-60'
60-100'
above 100'
and so on

Once above a few hundred feet you can do a regular approach.
The plan may vary according to conditions. So think about it and go over it in your head as you are waiting in line to be towed.
You should also have a plan of action on what to do if you are given the rope.

Chris McKee - 2005/08/25 13:36:00 UTC

Additional to Matthews List ...
Weak link break at 50 feet with tow cart still attached ....
Answer: Roll on landing to keep cart behind you

BTDT

Linda Baskerville - 2005/08/25 13:51:22 UTC

Having trained with Sunny, I can tell you that they work the weak link break into your training - i.e., Sunny pulls the release on you at various points.

Basically, you have to have your anticipated escape mode in mind at all times as you tow up - I repeat my mantra (literally) as I am being towed up, of where I can land if the weak link breaks so that I don't have to think about it to make a decision on short notice, but will be able to respond immediately. At Ridgely, (towing west) it would be " straight ahead straight ahead straight ahead" , then as I see the altitude increase enough it switches to "RC field RC field RC field RC field RC field" and then lastly as the altitude becomes enough it is "windsock windsock windsock " until I feel I am out of the "emergency" adrenaline response altitude and in normal approach zone.

At Blue Sky (towing south) it would be much the same thing although you could substitute Soybeans (to the right) for RC field.
I'm sure with enough experience, I won't have to repeat my mantra on tow, as it will perhaps become instinctive.
Some regular sources of weak link breaks are: getting into the prop wash of the tug, and also skyrocketing out of the cart, and also hitting an abrupt thermal lift. I'm sure there are plenty of others - like various cart acroBATics.....

Scott Wilkinson - 2005/08/25 14:08:57 UTC

Thanks all for the great responses! Some really excellent points I'll commit to memory and work on.

That's great Sunny works with you on simulated breaks at Ridgely---not something we do at Blue Sky, so that's good! In addition to your mantras on where to land Linda, I'm always thinking (if it breaks) "pull in, pull in, pull in, pull in!"

Being a "large and tall" pilot (6' and 225lbs) on a big glider, I don't get pushed around as much by thermals...but then again, I'm pushing the weak link that much closer to its breaking point (since everyone tends to use the same test-strength line for the link).

Dave Rice - 2005/08/25 14:25:17 UTC

I've only had one weak link break while aerotowing and it happened while I was still very low and over the runway. I was happy that I automatically pulled in as soon as I heard the snap and got slow. I'm glad that my reaction was to dive** at the ground even though it was really close to it. I was able to maintain manuevering speed and landed without incident.

**When I say "dive" I'm talking about the Falcon version of diving which I think is more a function of the pilot trying to go fast than of the glider actually getting its nose pointed at the ground. If I had pulled in as much as I did with a higher performance glider my results would probably have been different. Sometimes it's really nice to fly a Falcon.

Brian Vant-Hull - 2005/08/25 14:32:50 UTC

If you think you're too low out of the launch cart and pop the nose to get up to position, that will do it: sudden slow down of the glider. Try to correct smoothly, which is not to say do slow corrections; just don't jerk the bar.

Cragin Shelton - 2005/08/25 16:53:03 UTC

Scott,

I, like others, had weak-link break training at both Highland and Blue Sky. Sunny, Chad, Steve, and Tex have all been involved.

One very important item in the training, and a direct response to your note above... it is NOT obvious that a lockout will cause a break. Holding that assumption gets a lot of pilots in trouble, because they fight their way through trying to correct a lock out too long; they figure if it gets too bad, the weak link will break and they will be off tow in time to correct their flight attitude.

The truth is that most lockout conditions will NOT break the weak link. Weak links fail when subject to sharp forces / sudden changes in tension. Many lock outs occur smoothly as the pilot and glider move out of safe position and the HG attitude goes widely off the toe line direction. Therefore, a pilot on tow must always be ready to hit the release as a lockout is approaching. Do not wait for the weak link to "save" you.

If you have not done so, get a copy of Towing Aloft by Pagen and Briden, and read about both weak links and lockouts in that book.

Scott Wilkinson - 2005/08/25 17:59:20 UTC

Good points Cragin, and yes---I've already deeply internalized the concept of releasing long before things get bad. (If anything, I'm more likely to release prematurely if things even kinda, sorta start to get bad---there's never a problem with that if you're above 200 feet!)

Of course, I'm sorry to say I've already had an unforgettable demonstration of what can go wrong without a wink link (in Holly's accident) and without releasing.

Out of curiousity---when you "trained" for this at Blue Sky, do you just mean it was discussed verbally? Or did Tex do "random releases" during tandems with you flying? (Seems like a hard thing to train for on your own.)

Cragin Shelton - 2005/08/26 06:58:52 UTC

discussion only.
Because of my size, I never had any tandems at Blue Sky. All my tandems were either many years ago at Kitty Hawk, or over at Highland
And the weak link discussions at Blue Sky included both truck and AT situations.
yea.. it is difficult to "surprise" yourself with a simulated break

Jim Rooney - 2005/08/26 11:46:12 UTC

Weaklink breaks are standard curriculum at nearly every tow park I've been to. At Highland, once we start doing pattern tows, the student never hits the release. We hit it and we hit it when they're not expecting it.

Ok, on with the first question....
Weaklink breaks happen for any number of reasons and one will catch you off guard at some point. Be ready and pull in.

One of the more interesting and poinient ones is the smooth air break. Towing up in smooth air, in position and you have a good weaklink... just towing along straight and level, nice and smooth... when the weaklink breaks. There's no appearent reason. No rough air, no rough glider inputs... it just breaks.

I see a lot of people break weaklinks by coming out of the cart too fast (staying in too long). They generally vault up into the sky and experience some quick loads from pitching up to catch the tug or pulling in not to zoom past it and the weaklink breaks.

The other common one, which is sometimes experienced at the same time as vaulting into the sky is smashing through the tugs wake. Sometimes the wake is unavoidable, but being on the cart excessively long increases your chances of hitting it.

Disclaimer:
Coming out too slow sucks too. I'm not recommending it.
A good cart exit should be like sliding out of it... it should just dissapear. If you sink after exiting, that's too slow. If you pop out, that's too fast. Flavor to taste.

Craigin makes a good point about weaklinks and lockouts. You can't rely on the weaklink to break. The way I teach things is that if your weaklink breaks, you didn't recognise the lockout fast enough and didn't hit the release fast enough.

Daniel Broxterman - 2005/08/26 14:28:42 UTC

While we're on this topic...at Wallaby in April the launch crew put a 2nd weak link in my system between the bridle and the Bailey. I fly with a two point, Wallaby-style release, with a single Bailey secondary. As I recall, here's the scenario they had in mind:

Pilot releases with primary, bridle catches on the tow line or release mechanism. If pilot becomes extremely out of position, the additional weak link would probably breaks prior to pilot finding and Bailey.

Does anyone else use two weak links, one on each release point?

Brian Vant-Hull - 2005/08/26 14:46:48 UTC

I also use two weak links, but in 8 years of use have never replaced that second one. I wonder if this second one has ever actually broken for anyone?

As to Batman's reply to Scott, while a new tow pilot has less experience with pulling off a flare, I don't see why an experienced tow pilot won't learn to perfect a flare. I do think it's harder to flare on a training hill due to less speed, so you may put a sharper edge on that particular technique. But learning to setup is arguably more important. And yet launch runs are important too! Do it all!

I used to be much better at going back to the training hill...

Chris McKee - 2005/08/26 15:15:44 UTC

An experienced HG pilot of any type should be able to flare, land equally as well. I just dont' like the statement that training hills are poor substitutes for landing practice. It is blatantly wrong and very misleading.

Rance Rupp - 2005/08/26 17:55:48 UTC

From what I've seen, folks that use a TH for 'flight' training (as opposed to L/L practice only) tend to fly slower on the approach just to savor the air time. That tends to 'teach' them to have a slower approach for their landing and that is a bad idea. Like Chris said, for experienced pilots, flares are flares, no matter where you are.

Chris, If you are talking about the whole landing, then I have to disagree with you about landing practice on TH's. I do believe that they are good for the launch and the flare. However, a landing also includes setup, approach (dbf or otherwise), downwind flying (sometimes), and flying through gradient. These are simply not doable at a 100' TH.

PS: Chris, I know you are familiar with all the other aspects of a landing, the latter clarification is more directed to the newcomers.

Chris McKee - 2005/08/26 18:17:47 UTC

Rance -

What I was referring to was the post that Scott made on one of the other threads that Training hills are poor substitutes for landing practice. It might be semantics, but "approach (dbf or otherwise), downwind flying (sometimes), and flying through gradient" are part of the flying phase. In my vernacular, landing is the phase where you are established on final, correcting for turbulence and approaching the flare. If anything, training hills tend to reinforce that more than any tow park due to the fact that usually tow parks have HUGE LZs that aren't surrounded by trees or hills thereby causing a gradient. Having received my H2 by flying Taylor's Hill 90% of the time, you are under turbulent gradient conditions most of the time. Especially when a spot is involved, the minute you take off you are mentally setting up your downwind & base then rolling final into thermals cooking off in the LZ and the forcing yourself to pop a picture perfect flare to avoid faceplanting into a load of fresh cow crap. If that isn't good landing practice than our foot-launch instructors must be miracle workers because most of the pilots they have graduated have done quite well on their first mountain flights.

Matthew Graham - 2005/08/26 18:28:54 UTC

Landings

Hi Rance,

My impression as an Observer is just the opposite. Hang 2s with lots of training hill landings really burn it in and nail their landings. I think this may be because they're nervous during first flights at altitude and fly really fast in general. The challenge is to get them to recognize best glide, best manuevarblility speed and min sink. Tow park have a better grasp of flying speeds but they tend to to come in slower on approach. Not too slow... just slower.

Tow pilots are definitely more comfortable with their approach patterns. However, they sometimes get nailed by the gradient. Thus, I always recommend both forms of instruction to new pilots. Why just do one or the other or get fixated on one form of instruction or flying.

Again, these are just my impressions.

Marc Fink - 2005/08/26 18:40:26 UTC

More Voodoo JuJu and other Superstitions

This arguement is beginning to sound suspiciously alot like the mountain launch arguement. How are the basic physics (not the environment) of landing a glider altered depending on where you fly?

Chris McKee - 2005/08/26 19:38:37 UTC

No one said anything about the physics of flying being different, only the difference in levels of learning depending on how you learned to fly either foot or tow. Nothing is set in stone, but in general, tow students come out as a H2 with much better pattern work, but not as defined landing skills. Foot launch students are usually better at landing due to the fact that we do it so many more times at a training hill and the focus is more geared towards the landing phase. As the pilots become more experienced with both types of flying, they become better balanced in all phases. I thought my flying was fine being a foot launch pilot, but my pattern work has become much better now that I've spent the last 3 summers towing.

Brian Vant-Hull - 2005/08/26 20:45:51 UTC

The physics ain't different, just the environment. ALOT different in both cases.

Marc Fink - 2005/08/26 20:52:35 UTC

Oh I see!

Thanks for that clarification.

I read "training hills are poor substitutes for landing practice"...and I thought they meant training hills were a poor place for landing practice. Silly me for misunderstanding that!

Still, I'm wondering if what was really meant was "high ground clearance is the best training for altitude approaches?"

Linda Baskerville - 2005/08/27 01:38:46 UTC

training hills and approaches

I had never thought of the training hill at Taylors as a place for DBF; perhaps that is a shortcoming in my training there. But at Taylor's, because you are relatively close to the ground (50' or so?), the experience I had, and the concept I developed, was to simply do up to a 90 degree turn (possibly a 180 if the ridge lift was adequate to give me the clearance) to land at a spot, or into the wind if it was cross. This parallels my idea of a final leg of a DBF.

At Taylor's as soon as I've launched, I'm not burning off altitude to position myself for a landing, I am coming down to land; my choices are so limited by low altitude, I do not have the option of choosing to come in with a lefthand turn or a right hand turn over the landing area to improve my approach or avoid rotor off of trees, I am committed to landing.

A DBF, to my mind, is how to approach a landing from high(er) altitude: getting the altitude right, the angles right, the length of the each leg right. Would a Taylors landing really be the equivalent in miniature(unless you were popped up to about 300 feet?) I've always thought of most training hill landings as simply being on final leg (with the possible exception of Oregon Ridge launches which really can afford you enough altitude from the top on a good day to pull off a DBF).

If I were to do a training hill style "DBF" as you describe above with one or two 90 degree turns at or below 50', when I'm coming into land at Ridgely, I think they'd haul me off the field and burn my glider, and then ban me from the flight park because the altitude is too low to be safely pulling off turns. It seems to me that Pagin references making that last turn onto final for a DBF from somewhere around 50' AGL (glider performance , and wind, and LZ conditions notwithstanding).

I'm trying to figure my way through this - it is an interesting question.

Maybe it is all simply semantics?

John Simon - 2005/08/27 02:11:56 UTC

Yikes!!! This is a nearly perferct XC!! Glad to hear your back in the
game Paul! Wish I would made it Thur. but had a few things that would not
allow it. I'll be trying again soon though. Great flight... congrats!!!!

Scott Wilkinson - 2005/08/27 04:16:12 UTC

I don't know Chris---this sounds like a seriously misinformed statement to me! I can't speak for Ridgely, but Steve Wendt's students are generally extremely good at landing, period. ("Landing" meaning the upwind/downwind staging area, figure 8s, DBFs---everything right down to the flare.)

If anyone thinks doing "landing practice" by 10 super-low flights in a day down a training hill beats 10 different approaches and landings from 800' in a day, then I'm completely dumbfounded!

I agree with Matthew---better to do it all. But if I had to pick one or the other, I wouldn't train for high-altitude flights and landings exclusively on a training hill. (Just my preference---I know others have done it very successfully, and I'm not bashing them!)

I rarely see anyone float down slowly at Blue Sky---I sure as heck was scorchin' through my approaches 7 times today! And they weren't all the same---I was mixing it up, moving the spot, practicing different approaches, etc.

Hugh McElrath - 2005/08/27 12:59:33 UTC

Jim,

While we are on the subject of towing and when to preemptively release: I think it was you who articulated the rule of three: if you have three oscillations and they are getting bigger or even not dampening out, hit the release.

Jim Rooney - 2005/08/27 18:48:08 UTC

Ding Dong

Yup, that was me. Something I picked up from Bo. He calls it "ringing the bell". (think of someone's body swinging back and forth as they occilate). If you ring the bell once, you can still fix it. If you ring the bell twice, it's time to get on it or get off the line. If you ring it three times, you best be off the line.

Hugh McElrath - 2005/08/28 12:13:43 UTC

Bah! Landing in fields is for pussies; real men land in trees!

Tad Eareckson - 2005/08/30 13:00:13 UTC

I see no reason to incorporate two weak links in a two point release system. I use three - and have been pushing for multiple weak links for five years.

Weak Link 1 is regular strength, is installed at the top end of the primary bridle, and makes things work like the primary release.

Weak Link 2 is a bit under double strength, joins the bottom end of the primary bridle and the Ronstan sailmaker's thimble, and provides protection in the event of a primary bridle wrap. The thimble keeps the primary and secondary bridles from sawing each other apart and prevents those two elements from functioning as a locking mechanism at the time separation is really desirable.

Weak Link 3 is regular strength, is installed at the port end of the secondary bridle and engaged by the pin of the port secondary release, and helps keep you alive WHEN your cable activated primary release fails or your primary bridle wraps. Also, if the primary release mechanism of your two point system is back home in the closet and/or you decide to tow one point...

I see no reason to fly with only one shoulder mounted release. If you dispense with the thimble or tow one point you REALLY ought to have two of them. If you incorporate the thimble or tow one point you REALLY ought to have two of them (see Steve Kinsley's 2005/08/26 post (don't quite understand that one - did the weak link lasso the eye of the parachute pin?)).

I've been thinking that all secondary bridles are way too long. Gonna start experimenting with 110 mm next Ridgely trip. Should reduce the wrap potential at that junction from no freaking way to incredibly no freaking way.

The barrel release I make incorporates a straight parachute pin and is lighter, stronger, and more efficient than the standard curved pin job with none of the latter's propensity to open as a result of contact with the basetube.

The weirdo contraption on Steve's right ought to be mandatory equipment for the one point aerotow crowd. It'll probably take a while but someone's gonna die 'cause he or she wasn't using it. I've taken his concept and trimmed things down to a little over the mass of a photon.

We have the most reliable, safest, strongest, lightest, cleanest stuff out there, I doubt there's any room for significant improvement, and it's too bad no one else is taking much advantage of it.

Dan Tomlinson - 2005/08/31 00:33:01 UTC

Tad's post is difficult to read but I've seen his work. His release mechanism is elegent in it's simplicity and effectiveness.

Marc Fink - 2005/08/31 10:02:15 UTC

One reason Tad's stuff hasn't caught on is that he usually writes from the "You all are stupid" or "You all are going to die" point of view.

He's a pretty sharp guy and makes interesting stuff. It would be a great help to the rest of us if he posted pictures of his handiwork--pretty hard to visualize his verbal discriptions. Does he actually produces these for sale to the flying public? I would also suggest he send out a few units to prominent individuals in the towing community for stress testing.

Scott Wilkinson - 2005/08/31 11:47:53 UTC

Tad's point of view is irrelevant to me---there's no intelligent reason to ignore his work if it is superior to what we're all currently using. (The sport would never improve if everyone thought "if it ain't broke, don't fix it".)

Jim Rooney - 2005/08/31 23:46:25 UTC

As with many changes in avaition, change is approached with a bit of skepticism. Rightfully so. There's something to be said for "tried and true" methods... by strapping on somehting new, you become a test pilot. The unknown and unforseen become your greatest risk factors. It's up to each of us to individually asses the risks/rewards for ourselves.

That said, I think I can speak a bit about Tadd's releases. I use both Tadd's and the traditional barrel release systems on a daily basis. Neither to me is superior to the other. They are extremely similar (both simple barrel releases). Tadd's are less prone to accidental release (read: nearly impossible)... this holds true for the basetube release scenario. This is both good and bad. What helps in one respect is a downside in an other. The question is how easily do you like your release to release? A traditional barrel is easier (think: while wearing gloves). Personally I don't find it to be an issue, but like I said, to each his own.

They are also easier to rig incorrectly and are thus more prone to the release failure where they hang up on the eye side of the pin. Granted, it's a bit of a trick to get it wrong, but it can happen and it is easier. It's an obvious thing when you know what to look for (but then, so is hooking into your glider right?).

At the end of the day, I like both release styles... they're just a bit different.

I think Scott has a good point. Tadd's oppinion is irrelevent (so is mine for that matter). The way I'd put it is that the only oppinion that matters is your own... after all, it's your butt in the sling.

$.02USD

Tad Eareckson - 2005/09/01 02:40:15 UTC

This is gonna be way too long - delete it.

Unless you're Dan. Thanks for the plug, Dan. Now you can delete it.

Yeah, I do need to get an article out on the Oz Report. I've written and revised one dozens of times and have had help from Kolie and Pauls Adamez and Gerhardt with photo sessions but I keep seeing things I need to set up better. Built a model which will illustrate components better than on the real deal but haven't gotten around to the camera work yet.

The documentation has always been available upon request and I do have photos of the glider mounted components which'll do until I'm ready for prime time.

The system itself has, however, been on display every time I've made it to Ridgely over the last four seasons and just about every poor slob who has failed to see me coming soon enough to escape has had a piece of my tedious evangelistic spiel. I apologize for allowing you to slip through the cracks, Marc.

The system has been scrutinized by the big guns from the Florida flight parks, Dennis, and some top notch competitors. The only negative feedback I've had has been from individuals whose only clue was that it didn't look like the big ugly chunk of metal with which they were marginally familiar.

This stuff needs more testing about as much as global warming needs more confirmation study. It gets tested more brutally than anything it's gonna see in the air long before it gets more than five feet off the downstairs carpet. By the time it leaves the the runway all that's left are minor adjustment and design tweaks. The secondary release system has been going up on Ridgely tandem flights for a couple of years. I'd have my equipment evaluated by someone who understands glider releases better than I do but I don't think that person exists. Sorry if that sounds arrogant but I've paid major dues and my AT, truck, and balloon equipment is top notch.

Although Scott's last comment really doesn't need expanding on but... If Bin Laden has provided a cure for AIDS and your white cell count was really low this morning...

My point of view (which was indicated in my post) is not "You're all gonna die" but "You're not dying fast enough" - i.e., there's so much in the way of redundant layers of protection that we can use shoddy equipment and get away with it most of the time.

You can build a city ten feet below sea level smack in the middle of Hurricane Alley, spend a couple centuries destroying the buffer zone, and mostly get away with that. I haven't had any need for a seat belt since I was three years old (and didn't have one).

We're launching off of carts behind highly experienced tug pilots at airports with windsocks and ribbons all over with releases and weak links at both ends of the string. Somewhat contrary to the bumper sticker shit doesn't happen - except in a wee tiny percentage of tows...

A year ago I went way out of my way primarily to share with the Manquin folk the technology I've spent an obscene amount of time developing on and off over the course of the past decade or so. The feedback I received was something on the order of "I guess it's adequate for use at this flight park but it's gonna take five extra minutes to replace a left downtube."

Eight months after my visit there was a catastrophic accident which probably could have been totally prevented and, at the minimum, greatly mitigated by 120 millimeters of Dacron fishing line. Let's call it a penny's worth. It doesn't cost anything, it doesn't weigh anything, it doesn't slow you down, it's not ugly, and, incorporated at the end of a secondary bridle, it'll last forever. What's the downside?! (Notice how I refrained from the caps lock key during that last sentence.)

One aspect of my system is really cool but expensive and not terribly critical. Other aspects can be incorporated independently, cost little or virtually nothing, and provide big performance and safety boosts.

Also, Steve had announced his "squid" release at winter's end. It wasn't available at your local WalMart at the time but, if the weak link might have left a trace of unpleasantness, that mechanism would have definitely cleaned things up completely.

I'm not shooting at Daniel but it's extremely frustrating to continue watching the occasional bit of death and destruction here and in Chicago and on the other side of the world when the technology to prevent it has been around for a long time.

I have some polio vaccine, it won't help with smallpox and AIDS, but it doesn't cost much and for nothing I'll show ya how to whip up some of your own in the kitchen.

A glider in line for a full installation recently left a fly-in in a couple of Hefty Bags so I have lots of extra components lying around and the summer's just about over. Any takers?

Hugh McElrath - 2005/09/01 03:11:32 UTC

Hey, Thad, Steve Wendt says my glider will be fixed in a couple of weeks, so it's still a candidate for early installation of your system.

Tad Eareckson - 2005/09/02 14:12:36 UTC

Yeah, sorry Hugh, didn't catch your announcement in the Pulpit Teams post before sending. I'll slap the RESERVED stickers back on the parts.

I'm wondering if the curved pin release is, in fact, easier to actuate 'cause the barrel has 143% of the diameter or my straight pin job is easier 'cause the barrel's over twice as long. I've never seen any evidence that there's any difficultly in opening either one (assuming one can get one's hand there at the right time). And since I never fly without them I most assuredly had thunk gloves during the design process. I can make the barrel any diameter I want but there's nothing wrong with the current model.

Given the choice between sticking something in the airflow (and, after release, my sternum) long and trim versus short and fat, I'll go with the former(never seen a Willow Ptarmigan diving on a Gyrfalcon).

I also get lighter and stronger. Both will function under a 200 pound load but after the test on the curved pin you'll have to stitch in a new one.

With a bit of extra effort the straight pin release can be connected to the bridle or weak link in locking mechanism mode but if one is that stupid my feeling is that that individual should either leave the sport, gene pool, or both.

And as of a week ago we know of one more curved pin failure than straight (1:0).

Not that this really matters anyway. If you fly with a proper two point system the likelihood that you will ever have to use a secondary in a critical situation is something around zero and if you're flying one point you should have a squid trigger in your teeth.

With respect to the full two point system... The conventional cable based system is not "tried and true" - it is "tried and unreliable". I hear of failures just about every time I go out. My system has NEVER malfunctioned on the bench or in the air and I have yet to see the scenario in which it can be made to. I suggest that old designs need to be approached with more skepticism than new.

And the stored energy version of my leechline lanyard based system is not "new". It's been around for over four years. In terms of hang glider evolutionary scale that's freakin' ancient. And the first evolutionary stage of this thing first went aloft eleven years ago Sunday. And there's never been a failure involving any of those. Is that long enough?

When I clip into a hot-off-the-press new topless supership demo for the first time I am not the test pilot. I'm just some jerk checking out a superior, proven, certified design.

Finally (for the time being anyway), nobody's opinion, including that of the pilot on the cart, is worth a rat's ass.

This system is not built on opinion. It's built with respect to stuff like physics, engineering, aerodynamics, mechanics, load testing, worst case scenario capability, and logic.

Weight is a bad thing, strength is a good thing.

Abrasion is a bad thing.

A 3/64 inch leechline lanyard running inside a faired downtube causes less parasitic drag than a cable housing four times that diameter velcroed to the out side.

A straight pin exerts less lateral force and experiences less stress in a barrel than a curved one.

No one ever died as a result of having a weak link.

A pilot having a finger (or pair of incisors) on the trigger has a greater chance of survival than one who has to hunt, peck, and pull.

A pilot using a release system with no history or capability of failure has a greater chance of survival than one using a system in which failures are routine.

Flying decisions need to be made on the basis of numbers. With a rosy future opening up in the field of intelligent design education there's plenty of room elsewhere for opinion.

Tad Eareckson - 2007/05/16 12:53:34 UTC

Got bored towards the end of last season and started doing a lot of archive searches along the lines of "weak link broke" with respect aerotowing to see if any of the little bits of string served any function more useful than do the sacred back up suspension straps and hook knives.

Short answer - no.

In more depth... Most of them happen for no reason whatsoever or 'cause somebody approached the tow line with a piece of fuzz. The minuscule percentage of breaks desired should not have been necessary.

Also did enough research in the tow discussion group archives to now be one of about half a dozen pilots of the hang glider flavor who understands what a weak link is (after all these years working on these systems).

News flashes...

The allegedly overstrength weak links of Mike/Bill and Robin had nothing to do with their accidents.

and

Holly had a weak link and it worked fine.

The sole purpose of a weak link is to keep the planes at the ends of tow line from breaking up. None of the tugs sustained any damage and all three gliders were in great shape all the way to the ground.

A really flimsy weak link can easily transmit enough tension override your control authority enough to slam you into the runway and stay intact all the way to that point. And you can use that same weak link to put the tug out of control.

A weak link may fail in a lockout but there's supposed to be a pilot controlling the aircraft who should have released long before things got to that point. If you're low and waiting for that safety feature to kick in you're playing Russian roulette - kinda like waiting for the air bag to inflate instead of hitting the brakes.

Let's pretend we're sailplanes and have to fly under government standards. The FAA says we gotta have either a tow line (see Holly above) or weak links at both ends of one that fail at between eighty and two hundred percent of payload (the weight of the stuff at the back end of the tow line). Expressed another way that's about 1.40 plus or minus .43 Gs. (The USHGA AT Guidelines specify the same top end but, consistent with the junk we use, say nothing about the bottom.)

Right now if a Karen/Ayesha sort of person approaches a flight line and asks for a weak link she gets a little loop which, when installed on a two point Spectra bridle fails when the tow line tension hits about 240 pounds.

If I make the same request I get the same piece of string and end up off the bottom end of what the FAA defines as the safe range - as does anyone else who suits up, clips in, steps on the bathroom scales, and sees a number larger than 305 on the left side of the needle. What I really want is something that blows when the line tension hits 620.

So the situation is that we're using chintzy weak links as compensation for chintzy releases that we can't get to in time and may not work even if we do (see Robin above) and gumming up flight lines for relaunches during prime time with one of the Dragonflies out of commission.

We should be breaking weak links at about the same frequency as do sailplanes and that we throw parachutes - never. And if a weak link is broken it should be because someone really screwed up.

Placement...

Weak links don't belong on the end of the bridle. All two point bridles can wrap. Every one point bridle I've ever seen 'cept for the ones I've made is way too long and can wrap. Bridles are most likely to wrap when released under high loading, i.e., when it's likely to be the least convenient and the highest loading possible is at weak link failure.

If you have a weak link at the top end of your two point bridle and/or one between your aerotow (shoulder) loop and an end of your secondary/one point bridle (as, insanely, is recommended in the USHGA Guidelines) you have one or two "maybe links".

The fact that Holly had no secondary weak link was inexcusable (that's cultural - not individual). If she had been using a two point bridle and it had wrapped she would have been in exactly the same position - towing one point and using 5 G weak link.

Weak links belong on the ends of the tow line. You can pick up a safety advantage by supplementing them with links on the bridle(s) but... this is way too long already.

Here's a quote from "Towing Aloft" (Page 349)...

"I witnessed a tug pilot descend low over trees. His towline hit the trees and caught. His weak link broke but the bridle whipped around the towline and held it fast. The pilot was saved by the fact that the towline broke!"

Lesson learned - Rather than reconfigure to a system that actually works when you really need it, just keep on doing things the same way and maybe you'll keep on getting lucky.

Chris McKee - 2007/05/16 14:57:36 UTC

I'm not positive, but I believe that Holly forgot to put in a weak link. The story I heard was Tex released the rope. You might doublecheck that, but I think that was part of the problem with Holly's incident.

Tad Eareckson - 2007/05/16 22:30:55 UTC

Thanks for the response, Chris.

I stand partially corrected. I checked back and although there were a couple of early reports that the tow line broke, the later and most reliable one from Steve stated that Tex let go. I plead guilty to locking in to first impressions and am glad to have learned that the tug pilot took appropriate and timely action.

I have to modify Holly's accident category a bit but my point still stands - if the tug landed and the glider was intact before it hit the ground, the weak link was not a legitimate factor.

What is consistent with all the reports is that her primary/two point bridle didn't make it to launch. One of the points I'm trying to make is that, even if it had, she was gambling that it wouldn't wrap and, if it did, she wouldn't be needing a weak link at her end of the line. She needed to have at least one on one end of her secondary bridle.

A couple more quotes from "Towing Aloft"... Page:

045

The towline release is a critically important piece of equipment. It is the device that frees you from the towline and it must be failure-proof.

338

The most common release emergency is when your release doesn't work.

Anybody else see a major disconnect (or, actually, lack thereof)? That was at the beginning of 1998 but we're still using the same crap.

Here's a quote in reference to 2005/06/08 at Ridgely...

Yesterday I was LUCKY that my weak link broke on my first launch (the next two pilots after me broke theirs at the same place, a thermal breaking off at the end of the field).

I think the Russian roulette analogy is a bit generous. I don't think you're gonna be lucky an average of five outta six times. We need to have pilot control of these situations. In accordance with USHGA Guidelines, you need to release immediately at low altitude if:
- you're
-- pointing more than 20 degrees away from the tug;
-- rolled past 45 degrees; and/or
- your oscillations are getting worse.

Danny Brotto - 2007/05/16 23:15:19 UTC

Weak links are not a secondary release system...

... they help and hurt under various circumstances.

http://www.dynamicflight.com.au/Reading/WeakLinks.html

Marc Fink - 2007/05/17 14:06:06 UTC

"Captain, there's a black hole dead ahead and its drawing us in.."
"Scotty...full reverse on warp thrusters..get us out of here now!"

Tad Eareckson - 2007/05/17 23:03:32 UTC

Thanks very much for that link, Danny. I feel so much less alone now. Wish I had known about this James Freeman person before I duplicated a lot of the typing he had done two years prior.

Still needs some evolution though. A small percentage of the AT crowd has figured out that the weak link belongs on the end of the tow line, but I only know of one other individual (Marco Vento in Portugal) who has figured out that a weak link is not a cheap piece of knotted string.

He's using Tost sailplane weak links which I had checked out but shied off from 'cause, while you can get inserts for whatever failure point you want, the base structure is really overbuilt for the range in which we're interested.

I subsequently developed a color coded system based upon two leechline elements stitched together, the number of stitches determining the strength rating, with a tolerances within plus or minus twenty percent. My predictions are that these things will last forever - will not wear out or degrade with use - and undesired (i.e., all) weak link breaks will become a thing of the past.

They will probably be adopted at Ridgely - we're currently working out a few options. A 400 pound weak link will keep solo gliders from 250 pounds up within specs and leave tandems no worse off than they are now. We can temporarily pop something on the end of the heavy stuff for the Karen/Ayesha sort of person.

If/when this stuff flies although you'll still be able to use your little loop of Greenspot, there will hopefully be a penalty for having your fuzz give up the ghost immediately or shortly after the Dragonfly gets loud. If you would prefer to be in charge of the decision as to when to terminate the tow, lose the fishing line and make sure the bridle eye is big enough to clear the spinnaker shackle if you're still using that crap.

This new technology is an adaptation of a concept I developed for integration with my primary and secondary bridles and started using last season. About a month ago I got slapped really hard and was able continue on behind the tug. No way I'd have survived that with a conventional weak link. It's a really good feeling to know you're not riding up on the brink of disaster the whole time.

Marc Fink - 2007/05/18 14:16:20 UTC

Tad--I've said it in the past--I really admire anyone that seeks to improve safety in towing (becuase it is necessary)--but I really don't have the slightest idea what the frig you are talking about!

You toss around load limiting figures without any real asociation to breaking strengths and desired load limitations. Just because a weaklink on liftoff breaks doesn't mean it has failed to do what it's supposed to do. If you go out and get slammed in turbulence on lift-off and the weaklink breaks--the failure is not in the weaklink--but in the pilot's judgement for going at that time in those conditions and/or not responding quickly enough to unload the pressures. Them's the breaks, so to speak.

You have a predilication for using scare tactics and pure speculation in some of your accident interpretations. You seem to expect that people to accept your equipment and ideas based on your convictions before they're proven.

Please get in touch with Peter Birren and get some info on development and implementation of safety systems. When you have a safe system based on meaningful quantitative test results--then present it in a positive way. I promise I'll be the first to adapt when and if it passes muster.

Jim Rooney - 2007/05/19 01:43:49 UTC

yeah, but speculation and 'conviction' are so much more fun

Glad to see you recognised the black hole just before it sucked you in... too bad it's too late to avoid it... enjoy your pointless debate

Tad Eareckson - 2007/05/19 12:09:20 UTC

Marc, the archives are littered with examples of you not having the slightest idea what the frig people are talking about.

If you bother to read my previous posts in this thread and run some grade school arithmetic you will note that I haven't tossed around any figures. Those are FAA and USHGA figures.

I've been flying at Ridgely since its first weekend of operation. I've seen and heard of a lot of weak link breaks at takeoff but none of them has involved somebody getting slammed at that point so hard and fast that his glider was in danger of failing and he didn't have time to get to a release either ('specially if that anybody is Steve or me). John Dullahan hit the classic worst case scenario about a year ago with a release actuator mounted in the worst possible location and still did what he needed to.

Define "proven". Is the equipment you use "proven"? By whom? What standards? Where's the documentation? What muster did it pass? Do you have a clue as to the tow line tension required to break your weak link? Do you have a clue as to how much tension you're normally dealing with behind a tug?

You're not using your equipment because it passed muster. You're using it 'cause a long time ago somebody at the only shop in town tossed together a half baked idea and sold lotsa them.

Where do you come off with the assumption that I DON'T "have a safe system based on meaningful quantitative test results"? I've offered several times on this server in the past couple of years to provide documentation to whomever wants it. It's up to 117 pages now. I don't recall any requests from you (or Jim, for that matter). The late Reverend Falwell made much more powerful arguments preaching from and to points of ignorance.

You still in the Skysailingtowing group? Did you bother to read my posts or download the file I put up last winter (he asks rhetorically)?

It appears that Peter Birren is the only one who did.

And yeah, I've read Peter's stuff and corresponded with him. I got turned onto the closed bridle way of doing things by him. His system takes care of some vulnerabilities inherent in our opening bridles but you gotta reach for the lanyard and I can make a pretty good case that in the real world my system is safer. We've both perfected things as good as they're gonna get in our respective fields and we're not gonna learn anything more from each other.

By the way - I don't do speculation and convictions. I do accident reports and physics. If you have evidence to the contrary please cite it.

Marc Fink - 2007/05/19 12:58:31 UTC

Tad--you have in fact made many erroneous statements concerning accidents--mostly to back up your convictions of the faulty nature of towing. The simple fact is that hundreds of thousands of tows using weaklinks in their present configuration successfully bely your contentions that we're all crazy for towing that way.

Simply put, your statements are irresponsible and are based on your personal interpretations.

I am a tow operator--as well as a "towee." I also do aerotow tandems. Using greenline or similar line, which generally tests at 125 lbs +- 50 lbs is widely accepted because it simply works well and relatively predicatably for the enormous range of conditions and applications in towing. If this weren't true, then accident rates would be much higher and these kinds of weaklinks would have been abandoned along time ago.

A 400lb load limit for a solo tow is absurd. You claim in-depth knoweldge of what you're doing--but do you know what kind of stitching your using, what kind of tack, and how it affects the integrity of the join you're doing?

Last year's jihad was against releases--now you're going after weaklinks.

Everyone supports you making efforts to improve things--but in the process you trash the present methods as somehow being an accident waiting to happen. You might not actually say it--but the implication is that both the operators and towed pilots are being irresponsible for using faulty equipment and practices.

Do pilots need to constantly review their tow systems? yes. Do weaklinks--being the weakest link in the system, after all--need to be carefully inspected and frequently changed? yes. Do we need to constantly try to improve things? yes. Do we need to scare the daylights out of pilots with doomsday scenarios and suggest punative action for using widely accepted practices before something better comes along? Definitely not.

My apologies to the list for waking this sleeping giant.

Tad Eareckson - 2007/05/19 21:29:05 UTC

Marc, let's take the weak link you described - 125 +/-50 - and put it on the end of a one point bridle. Its top end is 175 which doesn't happen until the tow line hits twice that which is 350. That makes it a (350/300=) 1.17 G weak link.

I'm talking about a 400 pound weak link THAT GOES ON THE END OF THE TOW LINE where it benefits from no force split and is thus a (400/300=) 1.33 G weak link.

So you and I are talking about a tow line tension difference of fifty pounds or a third of a G.

And I'm still 200 pounds or two thirds of a G below the limit specified by USHGA and the FAA. (If you have a problem with that figure take it up with your Regional Director - not me.)

Let's look at the bottom end - same glider, same bridle. 75 times two is 150 pounds which is half a G and .30 below what the FAA says is safe to tow a glider under their jurisdiction. And it gets worse if you put it on the end of a two point bridle.

I see you still haven't bothered to look at my documentation which answers the questions about my weak links but they don't deviate more than 21 percent up or down. You seem to be quite content with a tolerance of 39 percent. (I also note that you continue to be content to throw out broad accusations without citing any evidence.)

If hundreds of thousands of tows have been completed successfully then tens of thousands of attempts haven't.

Here's some stuff off the wire from the local crowd (none of which coursed from my pen)...

NEVER TRUST A WEAK LINK!

Expect two things from your weak link:

(1) It will break unexpectedly at the most inopportune time, with no warning adn no indicaiton of a flight problem.

(2) It will hold strong and fast whenever you move into a lockout.

Then I switched to the falcon and the birds were singing in tune again. Until the brand new weak link vaporized at about 1000 feet for no apparent reason.

At 840 feet I noticed the tug was high and rising so I pushed out a bit to catch up. Broke the weaklink and stalled since I was so nose-high.

First try was a notably short flight, with a weak link break moments after lifting from the launch cart. The wind had shifted, so I had a down-wind landing, rolling in. I succeeded in dragging a knee instead of a toe on one side, so I earned a nice strawberry scrape.

I got five launches with three full flights on the US. Two weak link breaks. Both were non-issues.

Got to Ridgley after 12, late as usual and was one of the last to launch. Broke a weak link. From now on I use a new weak link every time since they're giving us dental floss now.

Kristen attached me to the plane and I rose briefly in the air. Pop! My weak link broke. (...The bad part is that sometimes the links just break, for no particular reason.)

Just a quick story with good educational value for other tow pilots. Yesterday I was the second of 3 off cart weak link breaks behind a 914 tug. Turbo was kicking in too quick says Bo.

I bent one this year when I had a weak link break right off the cart...

I had a weak link break at maybe 50 feet. I thought I was going to have to land in the soybeans -- the very tall soybeans -- when I looked at my angle. But, my glider stalled quite dramatically almost instantly (hard not to stall when you have a break), and dove towards the ground (a bit disconcerting from so low).

...I hit enough turbulence to break my weak link. #%*&!

Steve had a weak link break on his first launch just after leaving the cart and rode it in on the asphault.

A second later, we are horrified to see her weak link has broken. We know she has been well prepared, but we want her first flight to be perfect.

...but at 400 feet my pussy-##s weak link broke.

I had a late start due to a weak link break.

Being a "large and tall" pilot (6' and 225lbs) on a big glider, I don't get pushed around as much by thermals...but then again, I'm pushing the weak link that much closer to its breaking point (since everyone tends to use the same test-strength line for the link).

I've only had one weak link break while aerotowing and it happened while I was still very low and over the runway. I was happy that I automatically pulled in as soon as I heard the snap and got slow.

One of the more interesting and poinient ones is the smooth air break. Towing up in smooth air, in position and you have a good weaklink... just towing along straight and level, nice and smooth... when the weaklink breaks. There's no appearent reason. No rough air, no rough glider inputs... it just breaks.

Broke the weak link at 100' this time. The tow was a little rowdy, but not that bad. Don't know what caused the break.

This time the link broke at 900'. Damn.

Broke the weak link at 1000'. And it was a fairly mellow tow.

I was in line early but had a green tow pilot. My weak link broke after an extremely fast 350 feet.

Anyway, on my first tow, Tex entered a thermal at just over 1100 AGL, and I failed to track properly behind him. I got turned away from him (not badly) and as I was about to get back into position the weak link broke at 1200 AGL.

I could feel a huge gust hit right as I came off the cart. Uh oh. I was right behind the tug at maybe 100 feet when my link broke. (Kev said yesterday the weak link might have also broken because of the very powerful tug, which throttled back yesterday.)

My weak link broke for no obvious reason at ~2,000' as Zack was pulling me in a wide turn to get back into a thermal he had found earlier.

And, somehow, after all these years, I've never heard anyone say, "Thank gawd my weak link broke! My crossbar was about to go!"

We're too close to and often off the bottom end on this crap. This stuff doesn't happen to sailplanes and they couldn't afford it. We've just accepted it 'cause we think that's the way it's gotta be.

This isn't about trying to make everyone think that he's gonna die 'cause his weak link popped at twenty feet. This is about trying to put the decision regarding termination of the tow in the hands of the pilot - where it belongs.

Tad Eareckson - 2007/05/19 23:00:28 UTC

Make that forty percent.

Chris McKee - 2007/05/20 02:53:35 UTC

One thing in all of these quips that you cut/paste from our posts that you haven't mentioned is that not all of these weaklink breaks are from brand new weaklinks. A couple of those posts were mine and I don't tie a new weaklink every time I fly. Usually I go 10 or more tows before I decide to retye it or it breaks and I have to anyway. I always check my weaklink visually, but if it breaks, I pull in and make my decision on where to land. If you are getting into a lockout and blaming it on a weaklink, than your decision ability is flawed in the first place. If you get out of position on tow, it should be the pilots decision to use his release and go around for a second time than blame a lockout on the weaklink NOT breaking.

I agree with Marc (scary!) Last year we listened to rant after rant about the releases. Are we going to have to revisit this new topic each week until that vein in someones head begins to pulse rapidly and they decide to beat you silly with a broken downtube?

In all seriousness, we all care about safety ... and none of us will beat you with a downtube, but we will all fantasize about it if you keep this up!

Tad Eareckson - 2007/05/20 15:57:51 UTC

When I make the decision to sacrifice a day and pump into the atmosphere the CO2 it takes to get to the bridge and beyond, I don't want to stand around cooking in my harness while the soaring window evaporates - even on the rare occasions when there's more than one tug running - 'cause people with unreliable weak links get connected to the tow line in front of me - and then go back in line in front of me with my lift ticket subsidizing the expenses.

I've been to Ridgely twice this season and have twice been subjected to same already from gliders within a couple of positions of my place. Both times the pilots were using antique weak links which had been near or off the bottom end of the scale even on their first flights.

Someone with a weak link below a .8 G capacity on the end of his bridle is not prepared to fly. I don't even want him near the tow line while I'm stuffing battens if he's affected the length the line will be by the time I cross the taxiway.

Selfishly - I wouldn't even want him paying Highland for the extra tows 'cause I want him up there marking thermals for me. (I need all the help I can get - all the sailplanes are gone and the vultures have been absolutely negligent so far this year.)

Chris, neither you nor anybody else is forced to read anything with my name on it - you don't even have to delete it from your mailbox anymore. But the only time your decision to fly with a questionable weak link (and all of them are questionable now) doesn't have a negative effect on everyone else is when it pops and you claw your way up anyway.

The last two sentences of your first paragraph are a reiteration of what I and the author of the link referenced by Danny have been saying.

Marc's statement about the reliability of Greenspot weak links is nonsense.

The bottom end of a Falcon 140 is less than half of a Talon 150. And they and everything in between get the same string?

Weak link ratings are not selected as a function of the range of conditions. They exist solely to protect the airframe. As you said Chris, they do and can not ensure your control or protect you from a lockout.

You're not going to be seeing much of an effect in terms of accident rates as a result of shoddy weak links. You will see a higher per day rate of landings and takeoffs. We see them.

The statement that things are just great 'cause if they weren't we'd have done something better is like saying that the water couldn't possibly be hot 'cause all those frogs would've jumped out by now if it were.

I was, by the way, well aware of the fact that you and lotsa people don't bother changing their weak links when they should but that's irrelevant 'cause -

A. That happens to be the temperature of the water; and

B. We all know from personal experience (yours truly included) that you can have a brand new loop of Greenspot break straight and level fifty feet up in glassy air for no reason whatsoever.

There just aren't any AT weak link breaks in situations in which our six G airframes are being threatened. A weak link goes 'cause a tug is climbing too fast? Was a cross spar about to blow? And Lauren doesn't even weigh anything. This is bullshit.

Here's what I'm proposing - and I've shifted to another flavor implementation since starting this thread.

You find out how much you and your stuff weighs. If need be you step on the bathroom scales out at the flight line.

When you get your preflight check you say "250 pounds."

The launch person hands you a Gray/Blue 360 pound shear link with a tow ring incorporated in its aft eye which puts you at right about the middle (1.44) of the FAA's .8-2.0 G range and everybody's ass is covered.

You can see what one of these things looks like at:

http://www.flickr.com/photos/aerotowrelease/

As for me, 310 pounds, I'm gonna sign the waiver and use 600 pound/2 G shear link with an error could spill me a hundred pounds into the red zone 'cause I'm not worried about my glider breaking up. (Actually, that probably won't happen 'cause the Dragonfly tail may be a limiting factor.)

You run your bridle through the tow ring and connect the bridle to your release.

You get to launch and the launch person unclips the previous shear link from the carabiner and replaces it with you.

This weak link will only fail when you want it to which, as you pointed out, Chris, will only be well into a lockout and long after you should have tested the functionality of your release.

If it does fail, which should happen at a frequency less than that at which your parachute is deployed, you are requested to secure the back half of the shear link before releasing and stowing your two point bridle.

So, Chris, if you're absolutely positive that there is no room for or possibility of any improvement in these systems, just click on by. Otherwise, critique what I'm saying.

I really do appreciate efforts to correct me when I've made an error like the Holly/tow line thing. (I'm still waiting for Marc to provide a single quotation supporting his accusations.)

Brian Vant-Hull - 2007/05/20 17:25:27 UTC

Tad Eareckson - 2007/05/16 12:53:34 UTC

Got bored towards the end of last season and started doing a lot of archive searches along the lines of "weak link broke" with respect aerotowing to see if any of the little bits of string served any function more useful than do the sacred back up suspension straps and hook knives.

Gee, Tad, I've used my hook knife and been glad I had it.

Don't feel qualified to comment on weak links. What follows is pure gut opinion and therefore not subject to argument. Have to admit I don't know of a case where someone was clearly saved by one. I popped 5 in a row once while trying to learn how to tow a K2. Really don't know whether the breaks saved me or not, but clearly I wasn't handling it smoothly and could have been getting myself in trouble. Whether or not it's true I always feel comforted by the thought that something is designed to pop before the forces get too large, and feel better with something weaker rather than stronger. Pure untested psychology.

I think you'd want them breaking every now and then just so you know they CAN break. Is 1 break every 50 tows an acceptable number? I think right now we're hitting about 1 in 20.

Tad Eareckson - 2007/05/20 23:16:27 UTC

Hi Brian,

I didn't state that very well. I do still have a hook knife available above my parachute container but, since I'm never flying near bodies of water more formidable than the upper reaches of the Choptank and Tuckahoe I find myself asking myself why with increasing frequency lately. Could come in handy in a tree but that ain't likely flying from Ridgely either - even for me.

If I ever heard of your hook knife incident I've forgotten - unless it involved falling out of a tree at High Rock. Can you fill me in?

If you used your hook knife as a means of leaving a tow line behind please REALLY fill me in 'cause my contention is that the only way that can happen is if your release and bridle system REALLY sucks to begin with.

There are a set of USHGA AT Guidelines which REQUIRE you to have a hook knife but RECOMMEND that you have a secondary release. Major priorities crisis.

A little aside - I don't think you can learn to tow a K2.

Here's the deal about weak links. I don't think you get it. Don't feel bad. I JUST got it within the past few weeks - months after reading a post on the towing list from somebody who gets it. The guy on the link Danny cited gets it.

THE WEAK LINK IS NOT THERE TO SAVE ANYONE. THE WEAK LINK IS ONLY THERE TO SAVE THE PLANE.

The RELEASE is there to save you (and I commend you for being a member of the minority of pilots who appreciate the importance of having a hand on the actuator at all times).

You only need to have the weak link go a bit before the cross spar (I'm ignoring the tug for the purpose of this discussion). We've never been anywhere close to that.

Even a flimsy weak link at the bottom end of the acceptable range (.8 Gs) can hold enough to put and keep you in a lockout. In a lockout you - by definition - have NO control of the glider. The only way to regain enough control to live, if you're anywhere near the ground, is to release.

The weak link might go soon enough to let you live, or it might not go until after you're dead. You can't afford to wait and find out.

Your confidence must be in your abilities to make a correct and fast decision to release and physically implement it. Steve and I can handle the latter requirement by relaxing our jaw muscles.

We're asking the weak link to function as an emergency release to save the pilot. It cannot do that. We've dumbed them down so much that if you get waked by a migrating Monarch you're blown off tow.

I've been doing some testing lately and it's looking like the maximum tension the tow line/weak link/glider normally experiences happens while Bob is running next to you saying, "Have a good flight!" And I have an educated guess that says that the standard weak link experiences some degradation during this acceleration and in the course of the flight - even before it gets chewed up by the notch on the end of the spinnaker shackle gate.

In the weak link I've developed the critical element is isolated and protected and, in theory, will not degrade and will last forever. It either survives unscathed or it explodes at pretty close to the point you ask it to.

We don't want them breaking at a rate of 1:20 or 1:50. We want them to break at the rate sailplane weak links break - never. If we can't control the glider we should have released long before they break. (I'm gonna use your one in twenty guesstimate until somebody comes along with something better.)

If we want to be sure they break we don't want to test them in the air. We want to verify that on the kitchen table using the 776 pound capacity tester I built last winter. But I've done that already on a range from zilch up to 636 pounds. They work.

Marc Fink - 2007/05/21 01:19:31 UTC

You've aerotowed your kitchen table? Awesome!

Chris McKee - 2007/05/21 01:50:59 UTC

I've got a topless table ... glide ratio sucks though

Brian Vant-Hull - 2007/05/21 14:52:18 UTC

If the maximum force truly is largest right when the tug starts to pull you (and this seems eminently reasonable during a normal flight), and a lockout never approaches this force (don't know if this is true), then your contention that our weak links are entirely too weak rings true.

How have you been testing the forces? Could you (hehe) do us a favor and test it during a lockout?

I used my hook knife to get free of the glider while in the tree at HR.

I really like the idea of a mouth actuated release for the first 30 seconds of tow...been too lazy to put it into practice.

Marc Fink - 2007/05/21 17:05:41 UTC

Ain't no device going to mitigate the fact towing in turbulence is riskier and takes more piloting skill. Changing your breaking pressures is only going to shift the bar on the decision set that the pilot must make in those split seconds during initial tow. Tad is correct in one statement--the weaklink does protect the plane, especially during roll-out and liftoff. Upping the load limit means more trust will be placed in the towed pilot in doing the right thing. keeping the line under higher pressure at initial lift-off, IMO, will increase the probability of lock-outs over the broad range of pilots and conditions, while increasing the risk to the tug as well.

When Tad succeeds in convincing one single very experienced commercial aerotow tug pilot that his system is better and safer, then I'll start taking his ideas seriously. Tow operators are the ones who really have it on the line, so to speak, and if and when a better idea comes along they will adapt if it improves the safety or efficiency of their operations. Untill then, your still a test pilot.

Dan Tomlinson - 2007/05/21 18:18:18 UTC

risk management

People who calculate risks and returns often use a quantitative technique. They multiply the expected probablility of an event times the "value" of its consequence. The premise is that if the consequence is relative modest you can tolerate a realitively higher probability. In our sport unfortunately the consequences can be extreme, therefore it is prudent to lower the probability of a serious consequencal event as much as possible. While I am sure it has happened I have yet to see a serious outcome from a premature weakling break. On the other hand a weak link that doesn't function when it should can amd oftem has led to a catastrophic result. It seems that the lesson is to err conservatively, better to break too early than too late.

Last year Tad carefully looked over my harness while sitting under the canopy with nothing else to do. he found a significantly frayed line that could have resulted in a serious accident for me. I was at first reluctant to listen to him since he always seems to be such an alarmist, but upon inspection confirmed that he was right. I took two lessons away that day, one preflight your harness as well as your glider, and two don't discount someone's observations based upon your own preconceived notions.

Mike Lee - 2007/05/21 18:44:42 UTC

links

A funny thing occured to me while flying this weekend......
I can't recall a weak link breaking on launch or climb-out
in the mountains......
Flying both affords me the chance to relax my brain......LOL
Hope to see ya'll soon
'Til then, mike

Tad Eareckson - 2007/05/22 02:13:19 UTC

Marc,

Thank you for contributing something halfway responsible to the conversation - for a change. It would be nice if you acknowledged a few things with respect to your previous posts which you made without bothering to read and/or take the time to understand what was being discussed but I'll take what I can get.

However...

First off, since USHGA specifies an upper - 2.0 Gs - but, for some bizarre reason, not a lower weak link limit, can we agree that at some point there is a safety compromise by using and excessively feeble weak link?

Yes? Good.

Now, can we determine a value for that lower limit? The FAA sez 0.8. Any objections to that figure? No? Good. Zero point eight it is.

OK Marc, listen good. THE WEAK LINK ABSOLUTELY DOES NOT PROTECT THE GLIDER AT ROLLOUT AND LIFTOFF. That's the one point of the flight at which it is the least part of the safety equation. IT ABSOLUTELY DOES NOT PREVENT A LOCKOUT. It can limit the extent of a lockout up high but down low you're in deep shit unless you're climbing.

No weak link can enhance your control of the glider in turbulence. You will be totally out of control, i.e., LOCKED OUT, before its strength becomes a factor.

The weak link keeps the glider from breaking up in the air. It may accidentally function to prevent the glider from slamming into the ground but provides no guarantee. If you start trying to ask it to perform a dual function you compromise its ability to get you SAFELY clear of the ground and up high enough to stand a reasonable chance of finding lift.

Like James Freeman said - "None of this is rocket science. It is basic physics combined with elementary mechanics."

There are only two things you have to consider with respect to a weak link - what strength and where to put it.

If you listen to PETER BIRREN (http://www.birrendesign.com/LKAero.html) (Marc) or me, you put the weak link BETWEEN THE TOW LINE AND THE BRIDLE. That way you don't have to worry about the bridle wrapping at the tow ring (carabiner) if the weak link fails. He suggests a quadruple loop of 130 pound Greenspot which, assuming a quadruple loop is twice as strong as a double loop of the stuff I tested, translates to FOUR HUNDRED AND FOUR POUNDS (Marc).

I interpret your second paragraph to mean that you will never, under any circumstances, review the data and attempt to understand the science yourself? You'll just follow the lead of someone with enough brains to do it for you? Fine. I'd just prefer not to hear anymore about equipment that passes muster when your definition of that is just a matter of what most of the rest of the sheep are doing.

Dan,

Thanks for crediting me with the catch but I think the most I saved you from was some awkwardness and discomfort. The stuff that kept you connected to the glider was OK.

Brian,

Thanks very much for the positive contribution to the discussion. Nice to be talking to someone for whom physics is not a totally alien and irrelevant concept. I knew there was intelligent life out there somewhere. Eternal gratitude for taking the first step in rescuing the conversation from the gutter to which, I feared, the Usual Suspects would once again manage to drag and leave it.

Last fall I developed a device based on the strength per stitch principle in which there are graduated sequences of stitches. You install it between the tow line and the glider. When the tug rolls sequences fail up to the holding point and the pilot can see (thanks, Sunny, for the idea of putting it on the proper end of the tow line) what is or isn't happening when. The gauge goes back down with the tug where it is retrieved and examined.

Only have a few tests to date but I myself went up behind it on my last outing and got something with which I'm pretty happy (dolly tires properly inflated, conditions and glider weight and configuration (full VG) recorded). Max load of about 160-175 pounds occurred at launch and was not exceeded in flight.

Recently I adapted a hydraulic cylinder and one and two point bridle/release configurations so's you can get constant readings in flight. (Hint: If you try this at home don't stare at the gauge too long or you'll have a real hard time finding the tug when you finally look up.)

With the 914's turbocharger kicked in (like they do for tandem) I got about 155 pounds. I'm calling the normal solo power setting 125 but I had trouble holding steady early in the flight and will need to go back up to get something with which I am really satisfied. A little pitch input translates to a lot of needle swing.

I'm guessing, at this point, that the in flight tension is only a function of engine setting, i.e., solo and tandem will be the same but the latter will be going up slower.

If you want more extensive info on the gauges lemme know and I can send you a PDF (149 K) (there's a schematic of the max tension recorder).

I once asked Sunny if they train students using induced lockouts but he pointed out that if you brought the bridle in contact with a nose wire and the top end wrapped you could have real serious structural problems real fast (oh, yeah).

However...

If you pop one of my links on the end of the tow line... I'd have absolutely no problem doing that at altitude and it could be a useful training tool.

We wouldn't be learning anything about tow tension though. As of a week ago we know about what steady state is, we know that the graph is going up as we roll away from the tug, and we know about where conventional weak links fail.

We could, however, experiment with different weak link strengths and get a subjective feel of the glider at failure.

I'm delighted to hear that you're interested in joining the Steve/Tad/Eastern Europe fraternity of folk who can release without doing anything.

Steve's three-strings are effective and free but the grommet/webbing interface needs work. My four strings are stronger and more versatile but are labor intensive and go out as part of a full secondary assembly (barrel release on the port side).

Take a look at the pitchurs -

http://www.flickr.com/photos/aerotowrelease/

and lemme know if you have further interest. I really like the confidence it gives me and I feel extremely bulletproof while I'm putting a safe distance between me and the grass.

Tad Eareckson - 2007/05/22 04:43:29 UTC

Gotta extract foot from mouth. Peter sez four strands - not loops. So a double loop of 130 at 200 pounds.

For me - 310 pounds - a "larger pilot" - a double loop of 150, extrapolates to 230 pounds. .74 Gs. Off the bottom end of what we all just agreed was the safe lower limit so I don't feel so bad.

I, for the purpose of this discussion, want to be smack dab in the middle of the safe range - 1.4 Gs so I do, in fact want 434 pounds which is between quadruple loops of 130 and 150.

Another correction - Shoulda read - less than half of the top end of a Talon 150.

Tad Eareckson - 2007/05/22 05:01:53 UTC

Here's part of a report from Joe in the 2004/09 issue of Hang Gliding.

Joe Gregor - 2004/09

Highly experienced mountain pilot aerotowing a newly-purchased glider experienced a lockout at low altitude. Witness reports indicate that the glider began oscillating immediately after leaving the launch dolly. The weak link broke after the glider entered a lockout attitude. Once free, the glider was reportedly too low (50-65' AGL, estimated) to recover from the unusual attitude and impacted the ground in a steep dive. The pilot suffered fatal injuries due to blunt trauma. There is no evidence that the pilot made an attempt to release from tow prior to the weak link break, the gate was found closed on the Wallaby-style tow release.

It's a real good bet that he was using a loop of the same understrength crap that "we" all swear by on the top end of his two point bridle. It didn't do anything to prevent or limit the extent of the lockout enough to keep him alive.

Chris McKee - 2007/05/22 10:56:56 UTC

Tad -

I'm confused. How can you blame the weaklink in your posted accident report when it clearly says the pilot did not make an attempt to use his release? Maybe I'm missing something, but wouldn't that be pilot error? If you are in lockout, than you as the pilot have made a bad decision in not getting off tow! Yes the weak link broke, but that wasn't the cause of the accident. The cause of the accident was getting into lockout in the first place. The broken weaklink was just a secondary order of effect. Most pilots are obstinate in thinking they can fly themselves out of a pilot induced ocillation, when in fact it would be MUCH safer to release before the PIO gets to the point of lockout. The stronger weaklink that you suggest would just complicate the matter worse in this situation. You'd just do your replication of a "Gayla Bat-Kite" and fly it straight into the ground. Short & simple - The weaklink did what it was supposed to do ... the pilot didn't.

Marc Fink - 2007/05/22 12:14:47 UTC

Was going to say the same thing--in addition to the pilot being unfamiliar with aerotowing and flying a new glider.

Put plainly, Tad, please explain how greater resistance to breaking a weaklink makes a lockout any less likely.

Tad Eareckson - 2007/05/22 13:08:50 UTC

Chris, Marc,

EXACTLY!!

That was pilot error.

If you are in lockout, then you as the pilot made a bad decision in not getting off tow!

Who said I was blaming the weak link?

The weak link didn't make any difference. It was a single loop of 130, it could have been ten thousand pound steel carabiner, the results would have been exactly the same.

(I don't think he was being obstinate or cocky - I think he was too scared to take his hand off the basetube and, according to Bill Moyes, shouldn't have had to but I don't want to digress right now.)

Chris - The guy died. How could a stronger weak link have made things worse?

Dan (Tomlinson) still thinks that dumbing down the weak link makes things safer. Read the title of Danny (Brotto)'s post -

"Weak links are not a secondary release system..."

(That's DOCTOR Freeman, by the way, I realize now I had taken note of him before as a result of an Oz Report reference.)

If the glider gets crooked low to the ground you need to do whatever it takes to get it straight. When we're free flying we have a reflexive weight shift response. When we're on tow we may need to supplement that action with a reflexive action with respect to a release actuator.

When we understand that dumbing down the weak link doesn't make us safer then we can start using them in the middle of the safe range - 1.4 Gs - rather than off the bottom end of it.

Chris McKee - 2007/05/22 13:24:03 UTC

I give up ... What exactly is your point in this whole thread? And what relevance did the accident report have to with this thread? Your logic train has derailed and I'm jumping off before it goes over the cliff. Fly how you want, with what equipment you want, blah blah blah. When you start showing empirical data with proven and qualitative results instead of clouding the issue with conjecture, misquotes, and speculation maybe I will be more inclined to listen, but right now it just seems you are grasping at straws and I have no clue what the point in all of this is.

By the way, sailplanes weigh considerably more than hang gliders, yet take off in the same conditions. One could extrapolate that the effect of the turbulence we feel in a HG would be significantly less than the sailplane experiences do to much more inherent stability. You also have moving control surfaces, longer wingspan, etc when make towing a much more controlled experience than HG. I think there are WAY to many variables that you are not including in your simple analysis when trying to compare towing a hang glider vice towing a sailplane. Apples do NOT = Oranges under most circumstances unless you are calling them both fruit.

P.S. Neither Apples nor Oranges have a good glide ration.

Brian Vant-Hull - 2007/05/22 15:30:50 UTC

I think Tad is saying the following:

1. The initial force when the tug begins to accelerate the glider is greater than the force experienced during a lockout.
2. Hence any weak link that would protect you from a lockout would have broken before you get off the ground.
3. Hence we are wasting our time with weak links that keep breaking on us.

The only problem I see is if this reasoning is correct why do weak links keep breaking in the air? If assertion #1 is incorrect then we definitely do not want links that never break.

So explain why weak links break in the air instead of at the initial pull and I'll be satisfied. But it truly needs to be a good explanation.

Tad Eareckson - 2007/05/22 22:25:33 UTC

OK (sigh), back down into the gutter...

Chris,

I'm not the least bit surprised that you have no clue. Lemme tell you what I told Marc a few posts ago. You have yet to request the documentation I first offered to make available to anyone on the list a couple of weeks shy of two years ago. It's loaded with data.

And, oh yeah Chris, what's the data on the stuff you're currently using?

My points are (listen carefully now)...

1. One size does not fit all (Marc), especially if that size is off the bottom end of the reliability range.

2. We can use high quality weak links in the middle of the safety range and totally eliminate any weak link break which does not involve a pilot who has really fucked up IF we don't continue to behave as a large herd of stupid sheep (fat chance).

With respect to sailplanes...

Last fall I consulted with a sailplane pilot who is also an AT release designer and learned that sail planes are, as you speculate, no brainers to control on tow.

First of all, the upper weak link limits are not mine. They are set by the FAA and the USHGA Towing Committee to cover the planes under their jurisdictions.

And last night we unanimously decided to adopt the FAA's lower limit as our own.

But since hang gliders are a relative bitch to control AND certified to withstand higher loadings...

SHOULDN'T WE BE MOVING THE WEAK LINK RATINGS FOR THESE ORANGES EVEN FARTHER IN THE DIRECTION I AM RECOMMENDING?

Now, back out for some more air...

Brian,

Three is fine, One and Two are not exactly what I'm saying. The rollout and steady state tensions are reasonably low and not that far apart but, yeah, I think that's plenty enough to do it. I'd feel more comfortable saying that we need a .8 G minimum and that minimum will lock out the asses of you and the horse you rode in on.

Here's what I think is going on with respect to conventional weak links - to answer your question with my best guess.

First of all - those are steady state numbers. I'm only interested in low numbers 'cause thermals and position irregularities can take you up to and beyond what the weak link will handle. I was flying one point and extremely poorly (all over the sky) and overshooting pitch inputs most of the time. You can REALLY swing the needle pulling that last trick.

The Greenspot is pretty marginal to begin with. And two knots are involved. A Fisherman's Knot joins the ends and the resultant loop is installed at the eye of the bridle with a Double Lark's Head.

Knots involve rather sharp bends in the line and, under loading, the fibers on the outside of the bend are subjected to more stress than those on the inside.

I think that what's happening is that the weak link is degrading in the course of the tow. You lose some outside fibers when you start to roll and little surges and corrections keep snapping away until... SHIT!

That's the best I have.

This just in from Portugal...

Subj: Re: [Tow] Re: Bridles and Releases
Date: 2007/05/22 11:35:22 UTC
From: marco_vento ~~ at ~~ yahoo.com
To: skysailingtowing ~~ at ~~ yahoogroups.com
6248

Tad (is this your name?):

We have been using the TOST weak links in association with either KOCH double release (for dolly launch and for foot launch) or MOYES release (for dolly launch or launch on wheels). The great point is the reliability and precision of these weak links. The weak side is the mass, but the pilot side, when the link breaks, is lighter - the protection box keeps attatched to the cable when the link breaks.

We are quite happy with it, although they are expensive, no false breaks occur anymore. The links are available in a wide range of calibrated break loads as well.

Please send us photos and info on your weak links - we are very much interested in it. Please also inform us how we could acquire some samples.

By the way, all my friends call me Vento - it's my family name but it means wind. Quite appropriate, isn't it? Please call me like that as weel:-)

Greetings

Vento

Too bad ya hafta hit the western edge of Eurasia to find a pocket of enlightenment relatively free of the fundamentalist nut cases striving to make sure we never crawl out of the dark ages.

Tad Eareckson - 2007/05/24 12:18:38 UTC

Hellooo? tap tap tap This thing on? cricketchirp cricketchirp cricketchirp

OK, nobody's listening anymore but just for the record...

Here's something Kevin wrote a year and a half ago when he was under the impression that I was defending a release that was inherently prone to premature release (but was, in fact, improperly adjusted).

http://www.chgpa.org/forums/viewtopic.php?f=2&t=1079
$15 pacifiers

Kevin Carter - 2005/09/24 21:49:39 UTC

One pilot in the Texas Open had three premature releases in a row with glider damage on all three and different degrees of pilot injury. I myself have had a low level release that caused minor injury.

When you are discussing the acceptable risk of a premature release.....take the blinders off man. It is a real risk that should be minimized and not taken lightly.

Now I'm guessing that even a curved pin barrel doesn't suck enough to be responsible for all that carnage so... Lessee, what else could... Oh, yeah.

So now that we have an easy, obvious solution dumped in our laps what should we do? Grab the pitch forks and torches and head for the infidel.

After screaming for "empirical data with proven and qualitative results" Chris has stormed out of the room and slammed the door behind him. And he now has absolutely no more interest in that very data I've had available years now than he ever has or will.

That data now includes reports on the results of 179 tests of weak links of various flavors and configurations, most of which took an hour or two to set up.

But hey, Chris is a Great Pilot and thus already knows everything worth knowing. And the most important thing is that it's not worth even considering unless everybody's doing it that way already.

Marc will not have demonstrably inferior and dangerous equipment pried from his cold dead fingers until the good stuff "passes muster". You could show him in a heartbeat performance tests which would instantly get the "Case Closed" stamp but what he really means is also, "What are the rest of the sheep doing?"

So he retreats from his promise to "be the first to adapt when and if it passes muster". Now he's gonna be the second to adopt it after it passes the muster of a tug pilot.

A TUG PILOT! Jim is a "very experienced commercial aerotow tug pilot" whose ability to evaluate these systems is also limited to the sheep thing. I know several "very experienced commercial aerotow tug pilots" who have absolutely no interest in or understanding of the stuff that goes on the glider.

With a brain half the size of that of a Turkey Vulture you have a thousand times the processing power to fly a lot more superbly than any of us ever will at either end of the tow line.

And just what does aerotowing have to do with anything?

Too bad Les isn't around anymore. And try running my stuff by Campbell.

Tow park operators? Steve Wendt is a tow park operator. The reason Holly didn't have a weak link when she slammed into the ground was because Steve couldn't have been less interested in the technology I had made a trip to share with him eight months prior.

Marc, it's a freakin' WEAK LINK. Only one of two things can happen.

If it breaks for no reason you're now (no) worse off than the One-Size-Fits-All Miracle Links with which you're currently so enamored.

If you think that a stitch of dental floss holds triple digits, rather than something in the ballpark of 18 pounds, so what? You're a superb tow pilot with the most reliable release system on the planet and you're totally confident that you can get off before you lock out. Besides, you have a weak link at the other end of the towline so the worst that could happen would be that you get stuck with the rope.

So exactly what is it that so frightens you?

Take a hint from Vento. He's a pilot, so he knows everything already, but also a mechanical engineer, so he doesn't. He's the only other hang glider person I know of anywhere using a quality weak link system. And, of course, he has totally eliminated premature failures from his operation.

Danny Brotto - 2007/05/24 21:58:44 UTC

Less pull...

Some things to think about...

Depending on set-up, the weak link does not experience the full load provided by the line to the tug. In a bridle like I use (only towing off the shoulders) the load is split between the 2 bridle connect points (where they attach to the harness.) So if the tug pulls at 100 lbs, the weak link only sees only a portion of those pounds; somewhere between 50 and 100 lbs. The exact amount can be calculated based on the span of the harness connect points and the length of the bridle; it's a 2-D statics problem that a first year mechanical engineer should be able to solve. The short of it however is that the weak link experiences less load than the pull force being presented to the glider. In practice, a weak kinl is not as weak as the simple straight-line breaking strength.

In the more traditional 3 point bridle (harness shoulders and keel connection) the load is shared among 3 points. This is a little more complicated 3D static problem but the point is again that the weak link experiences less load than the pull force presented to the glider.

We set gliders with strong tow pitch pressures up with a keel-forward bridle connect position. While can alleviates pitch tow forces on the pilot to almost nonexistent, it concentrates pressures to the keel/release and onto the weak-link assembly. I would fully expect that gliders set up with 3 point bridles for light tow force pitch pressure to break weak links more readily than the norm.

With the various tow bridle set-ups, a consistent "calibrated" location for a weak-link is in the tow line. The problem here is that we would see weak breakage as the tow rope caught things dragging thru the grass and what not. And then there's the additional variable of the tow line material. Spectra does not stretch much and does not have much “give”. This presents a different dynamic load than polypro that yields with stretch.

Marc Fink - 2007/05/25 00:26:39 UTC

Excellent points, Danny. We tow with an elastic polypro system in Maine--which I personally don't like cause I hate the "rubber band effect" (especially on tandems)--but others like the "forgiving nature" of the energy absorbtion.

There's yet a third variable missing from the discussion so far which I think is crucial and gets to the core of this discussion.

That is the drag of the glider itself through the air, which, depending upon many variables, can rapidly increase or decrease the pressures on the tow system.

And I say tow system--because I don't believe that you can look at this problem through one of isolation of just one component and expect that adjusting that one component can adjust for failings in other aspects of the system.

I suspect he'll kill me for mentioning it--but Larry Huffman has never broken a weaklink in 11 years of aerotowing. Is he lucky, beating the odds somehow, or only goes and tows in perfect calm conditions? I think not. Rather, he recognizes that safe towing is not a question of where you keep the tug or glider as an absolute priority--but that the overall safety of the tow has to do with towline pressure management. Thus, the pilot needs to anticipate what will happen to the pressure on the line and take whatever corrective action is necessary to correct a potential overbuild of pressure. It takes alot of skill to be able to respond with the right degree at the right time to prevent oscillations in tow pressures. These typically happen when transitioning spots of lift/turbulence where most likely the rising and falling of the tug and glider will be out of synch and therefore the proper input needs to be in anticipation of that lag.

I'm hardly an expert on towing and I tend to do my fare share of wandering around under tow, and occassionally break a weaklink (less than a dozen, ground towing since 1989 and aerotowing since 1996) when I just can't keep things in line when going through an especially strong thermal--which is just as well since I probably should have released anyway to work it--but how often do we find ourselves hanging on to the bitter end of the tow even though the tug pilot has dragged us through the core several times??

I've towed at alot of different airtow parks--and I see alot of pilots do things that contribute to marginalizing the safety of their tows beyond just the string and bridle they are attached to. Proper setup of the gear, attachment points, and angle of the harness can make a big difference in the pilot's ability to make smooth control imputs while under tow.

I see alot of gliders, mostly high performance ones, take off with their AOA set too high in the dolly. This encourages an early liftoff before safe airspeed and increases drag and the likelyhood of an unintended wing up early on. In some cases pilots simply let the glider go off the cart as soon as it starts lifting, rather than holding on while building airspeed and adjusting a lower AOA. The extra speed will increase stability and control, as well as allow the towed glider to rise up to a safe "holding" altitude to let the tug rise up to the same level and at the same time reduce line pressure.

Things happen so fast in the first few seconds of a tow that I'm not sure the average pilot could respond with the correct decision fast enough to take away the necessity of a weaklink--one that might occcassionally break seemingly unpredicatably too early.

My opinion is that if you feel that somehow the system is at fault for repeated weaklink breaks or other mishaps during your tows--then a reassessment of all the equipment and processes--including the most important one--your brain--is in order.

marc

Disclaimer: these are just my opinions based on my experience and observations--always ask your professional tow operator what is best for you given your equipment, experience and conditions.

Tad Eareckson - 2007/05/25 03:20:40 UTC

Thanks Danny,

Since the shoulder attachment points are so close together (about nine inches) and the bridles that span them are invariably too long, I cheat a little and just divide by two. For what I'm calling a two point bridle (pilot and glider) the attachment points are, by definition, widely separated, I recommend and assume a bridle length which yields a 60 degree apex angle. I divide by two, blow the dust off a little trig, and multiply each end by 1.15.

I am strongly recommending a weak link which goes between the bridle and the tow line. In the both the Tost and my weak link the critical element is isolated and protected. I'm hoping mine will be able to withstand a virtually unlimited number of landings in the gentle environment of the Ridgely strip.

Its rating will not degrade until/unless the base material is badly worn and I'll be disappointed if it doesn't withstand hundreds of cycles.

If I understood Tom Lanning right, the Australians use a high stretch tow line and a very low rated weak link. He says it takes some getting used to but definitely has some merits worth considering. I think I'll stay with Spectra 'cause I can't imagine the alternative does anything for one's fuel economy.

Marc,

More power to Larry but...

Let's define him as 250 pounds and towing off the shoulders. Put a loop of Greenspot on one end of his Spectra bridle and he has a 1.12 G weak link.

I'm 310 pounds. Put an identical loop on the top end of my point bridle and I have a 0.79 G weak link - just off the bottom end.

If you're sitting pretty straight behind the tug in glassy air with a brand new weak link and the thing pops for no reason whatsoever then skill has nothing to do with it. This happens all the time. And world class pilots rain out of the sky at competitions all the time. This happens 'cause their weak links are cheap understrength crap, not because they're deficient in the skill department.

You have selected a G rating for yourself. You have selected it on the sole basis of the material being what everybody else uses regardless of his weight. You tell me what you weigh, in what configuration you're towing, and what kind of bridle (material and material diameter) and I'll tell you what that rating is (when your string is very new, anyway).

Mike Haas, the subject of the accident report I quoted, assuming he was within the hook-in range of his glider, was using a weak link of between 1.11 and 0.79 Gs, i.e., at the low end at best and a little off the low end of the safe range at worst.

HIS RELATIVELY FLIMSY WEAK LINK DIDN'T AND COULDN'T HELP HIM.

You're still thinking of the weak link as an emergency release. It's not! It can't be! You need to reread the link Danny referenced. (Don't worry - it took me years to understand this.)

The only emergency releases that can be counted on are the ones controlled by the pilot (odd how Chris got so furious when we were agreeing on that point). Shit never happens so fast that the pilot can't react faster than the weak link. If the pilot can't make a decision faster than the weak link can kick in he shouldn't connect to the tow line. If he does and shit happens... Shit happens.

I have been flying with a high quality 1.12 G weak link (hmmm... that's exactly what my hypothetical Larry uses) since last season. I'd go a lot higher but the one at the tug end ain't that good. It feels so much better being confident that I'm not on the ragged bottom edge anymore.

http://groups.yahoo.com/group/skysailingtowing/message/6251
Re: [Tow] Re: Bridles and Releases

Marco Vento - 2007/05/24 16:15:32 UTC

Dear Tad:

I've seen the photos, quite clever I might say!

If you want to give a look at our operation see:

http://www.youtube.com/watch?v=K72Ql7Lnb1Q
dead

We use 1500 N and 2000 Newton weak-links. I am very interested in testing your links. Could you send some (let's say 2 of each?) to my adress (work adress):

M. A. Vento
Linde Sogas
Est. Nacional num. 1 km 38,4 Cheganças
Alenquer - Portugal
2580-381

Please tell me the costs and how could I pay you. (Bank transfer, credit card, ??)

Best regards
Vento

Tad Eareckson - 2007/05/25 10:14:07 UTC

P.S. Marc, just as you have arbitrarily determined that you're gonna tow at X.XX Gs, Hypothetical Larry will be at 1.12, and I'm gonna be dumped off the bottom of the scale, you've also put a new student at the bottom end of a Falcon 140 at 1.50.

So this isn't really about keeping everybody safe by staying within a hair's breadth of involuntarily popping off tow, is it?

John Claytor - 2007/05/25 12:03:13 UTC
Richmond

here is some raw statistics: I am about 215, loaded up harness 40 and fly a glider that weighs 85, 340 pounds total. I use the same weak link material as every body else, towing off of the shoulders with a weak link on both sides, equaling four starnds.

I break a weak link about once every two years. a little frayed is better in my way of thinking because I like my weak links weak.

If you are in the moderate range and breaking weak links all of the time, I am sorr friend but the evidence would point to technique, not inferior link material. If you are breaking these all of the time, you probably owe your health and safety to the system thay you may feel is failing.

Here is a concept:
When you are preparing to tow, sit on the cart on the runway ready in the position you are going to begin your role in. Now instruct the tug pilot to give you nothing less that full throttle. tell the person launching (who is really here to check your gear and communicate to the tug) not to push you into the role. Now the weak link will take its highest load during the flight and you are barely rolling on terra firma.
If it breaks you are safe. Just push out if you are rolling faster than you like. If it doesn't break than you are likely not to load up the link any more during the entire flight.

Actually I like the weak link a little frayed. And all of us should be ready for the weak link break during every second of every tow. Its part of the launch.

Tad Eareckson - 2007/05/29 23:04:08 UTC

Semi recovered from a punishing but rewarding weekend. Great day at Ridgely Saturday - even I could stay up long enough to get hypothermic and nauseous. Next two days were eaten up by a distant wedding and a lot of driving. Apologies to all my adoring fans for the prolonged absence.

Hi John,

The respect I have for anyone with enough brains and independence to say, "There's gotta be a better way of doing this." and start snooping around a West Marine store is equaled only by my contempt for folk whose immutable engineering standard is, "This is the way everybody's always done it." Thus the following flame pains me a bit, but...

For starters, the fact that you have weak links on both ends of your one point bridle is not relevant to the discussion. It doesn't hurt anything but, unless your bridle is excessively long (by which I mean anything over seven inches), it isn't helping anything either. What's pertinent to this discussion is that you have one end of your bridle retained by two strands.

One can't tell from the data you've presented that you've ever actually made it up to twenty feet before your weak link pops.

OK, I'm assuming that you tow a lot more frequently than once every two years and that what you meant was that the overwhelming proportion of your tows are successful? But you should be having zero breaks in a two year period no matter how much you tow. I'm taking a wild guess that that one average break does nothing to enhance your safety?

Also, when - not if, but when - that weak link gives up the ghost I want you to pay for the full tow and go to the back of the line so you're encouraged to use a better system and won't keep the next twenty gliders waiting.

I myself have had 224 tows of any kind dating back to 1980/11/14. Of those my ascent was limited by a dozen weak link breaks. Two of those were consequences of lockouts at altitude where safety wasn't much of an issue. In both cases I elected to allow the break - I could and should have released but had neither been instructed nor figured out that that was the proper course of action. (It is not known whether either of those lockouts was preventable).

So now we're down to ten relevant breaks - all of which were completely unnecessary and undesired. All of those constituted pains in the ass of various degrees and at least one cost me a really good flying day.

Last season I started developing the concept of stitching based weak links and incorporated it in my bridles. I ain't never gonna have no more weak link breaks.

I didn't start this thread 'cause I was, am, or will be "breaking these all of the time". I'm writing this 'cause everyone else is. As a consequence my lift ticket is too expensive, the wait for a cart is too long, and my flight park is operating inefficiently. To date I owe NOTHING to weak links - the "standard" version owes me big time.

In all of my research to date I know of ZERO weak link breaks which have prevented AT accidents and challenge everyone to provide a blemish to that record.

When I take over as Supreme Dictator of Planet Earth, the first thing I'm gonna do (after, of course, summarily executing all the single occupancy Hummer drivers) is mandate a 0.8 G lower limit for weak links (I'll probably raise that number later). You're struggling to hold onto the bottom end with new weak links and the fuzz is definitely gonna put you out of specs - so be forewarned.

I never said that ability to survive the roll qualifies a weak link for any part of the tow. It most assuredly does not. I need something slightly south of 175 pounds to get me - 310 pounds - moving and I sure don't want to be hovering around that figure. I need 248 pounds to get to the bottom of specs.

But, for arguments sake, let's say that a fuzzy loop of 130 pound Cortland is the ideal weak link for you. Are you gonna give a new loop of the same string to a 162 pound Falcon 140? Like Marc does?

Finally, how 'bout this... Lose your parachute pins and tweak your velcro so you automatically deploy when you hit three Gs positive. It's analogous. Like the idea?

I'm the freakin' pilot. I don't want some goddam lousy piece of shoestring telling me when it's time to get off tow. I will be the one to make that decision.

Hope you will be showing up for the ECC again this year. If you do, could you bring that side pull snap shackle release you developed? I'd like to see and play with it 'cause I think it would be quite compatible with the form of the shear link I'm using in conjunction with my own rig. A spinnaker shackle doesn't cut it, figuratively, 'cause it does, literally.

Although I couldn't disagree with your positions more I really do appreciate your positive contributions to the discussion.

John Claytor - 2007/05/30 00:39:57 UTC

You are right about the multitude of gliders that are subjected to the same system, and I can clearly see that one size probably doesn't fit all.

The snap shackle system I built never failed, and never had to be fixed or repaired during the time that I used it. The hardware is designed to release without any sharp or forged edges meeting the line upon release. if you have a spare shackle of that sort, bring it. I probably have a few in my sailing gear...

The release that I made (with the snap shackle), I gave it away to a pilot named Todd. He needed it to learn how to aerotow. The $150 for the Wallaby Ranch style releases hurts the flying budget... BTW the snap shackle is less than half of the cost of the spinnaker shackle, and the snap shackle ($22) is the most costly component of the rig.

I do have a story where a trike pilot towed me at Quest---Weak link worked---Everybody warned me about the trike pilot's style---Really glad to be here.
I'll save the details for the poker table next week.

Marc Fink - 2007/05/30 02:52:19 UTC

Tad, I'm truly dismayed at the prospect of you showing up at the ECC's--flying in that in environment is stressful enough without having someone walking around preaching imminent death to someone who aerotows with present systems.

If you don't think you can control your impulse to denigrate others for using something other than what you personally approve of, I'd just as soon not show up.

You gonna be a good and leave it alone during the comp?

Kurt Hirrlinger - 2007/05/30 03:31:24 UTC

weak links

What situations are the current weak links designed to resolve
Is it possible to apply an automatic release to HG

Tad Eareckson - 2007/05/31 01:03:19 UTC

And speaking of contempt for folk whose immutable engineering standard is, "This is the way everybody's always done it." - Heeeeere's MARC!!

If you had had education in reading and arithmetic enough to be able to follow this thread you would have understood from Post 1 that it's not about imminent death and what meets my personal approval. It's about getting gliders to altitude reliably on good days and based on accepted aviation standards.

It is indeed unfortunate that when, in an earlier post, you abdicated your "thought" processes to unspecified tug pilots you did not relinquish your posting rights along with them.

Just as Chris, obviously at this point, does not represent the unified voices of all on the list server, you most assuredly do not speak for the mass of the ECC participants - they're not ALL morons.

Equipment I have noted present at competitions past has included spinnaker shackles, twin and straight pin barrel releases, and redundant weak links. Those are all technologies introduced by yours truly. (I'll back off to "independently developed" on the first one if anyone can cite a reference prior to 1994/09/04).

At last year's competition Dennis Pagen said, "I agree." and went up with a pair of my barrels. The current and recently deposed Ridgely XC record holders fly with my design. PK was very happy recently after his maiden tow with the set he acquired from me at the end of last season. I suspect that Bob Lane's design I recently saw referenced in the Oz Report owes something to the secondary bridle assembly I sent down to Kevin a year prior.

Saturday night Sunny stated that the points I've made in this discussion sound solid and declared his intention to start flying with the shear link I provided.

(I hope everyone notices how Marc always slinks back under his rock without responding to questions like "By what standards is the equipment you use proven?")

John,

Yeah, I was afraid I remembered that you said you had given your release away. Believe you had incorporated a Ronstan snap shackle but I can't recall which one. Can you take a look at:

http://www.apsltd.com/Tree/d270000/e267100.asp

and see if you can find a match?

I look forward to the account of the trike tow and will keep an open mind but you gotta convince me that the weak link failure was necessary and would have occurred before I would have hit a vowel in whatever expletive I would have been uttering at the time.

By the way, I can provide you with a weak link of any strength up from the equivalent of a 123 pound loop of string that will maintain its integrity until your tow line tension hits that rating (245 pounds).

Tim (Kurt),

The current weak links are "designed" to pop for no reason whatsoever when you'd much prefer to be continuing up to a workable altitude and hold on to the death when your hands are frozen onto the basetube.

People think they're designing them to prevent lockouts. They're not and can't.

They should be designed as a failsafe to protect the glider up high - only the release can reliably protect the pilot down low.

Yeah, I think an automatic release would be doable but I also think you'd have to incorporate gyros and spend a lot of tow ten packs. As it is we have people with releases at both ends of the tow line and that should (but, yeah, doesn't always) work.

I think that if you want to spend money the best bang for the buck would be in the development of a computer simulator called "Lockout!" It's the area in which proficiency is most critical and the opportunity to practice is extremely rare.

Jim Rooney - 2007/05/31 13:27:30 UTC

Wow... this thread is still going?
Hahahahaha... as if this is shocking?

Guys, take all your equations and stuff them. We all know bumbelbees don't fly right?

Any tug pilot will tell you that this is all bunk. Weaklinks don't "protect" you from lockout, but I'll be damned if I listen to someone tell me that they don't break during lockout.

Try to get behind me without a weaklink... try... I will not tow you.

Cragin Shelton - 2007/05/31 18:07:25 UTC

Thread Advice

Weaklink - a bundle of threads tied in a loop.
Is this thread weak enough?
Here's a reading suggestion for at least some of the folks who have been playing in or reading this thread.
You can decide for yourselves who really needs to read it.

http://tinyurl.com/2ltzsw

Hugh McElrath - 2007/06/01 01:57:11 UTC

It is with great trepidation and against my better judgment that i enter this thread - but since when have I ever listened to my better judgment? In all the discussion about weak links, I think what has gotten lost is the idea of a primary release that can be actuated without removing a hand from the basetube - particularly in a panic situation approaching a lockout. I am quite happy with the one I have with a loop of line that goes around the palm - just slide the hand inboard 1/2 to 1 inch. I have accepted samples of Tad's and Steve's mouth-release prototypes, but confess I have yet to tow with them - primarily because I want the inventor to assist me in rigging it the first time. Also, last year I was still getting used to towing the U2 without a strap-on fin and didn't want any extra novelties. I seem to be pretty solid towing the U2 (finally) and will bring the samples. If I'm not in too much of a hurry during the comp, I'll be willing to try an alternate tow release. - Hugh

Tad Eareckson - 2007/06/01 12:27:40 UTC

Jim,

People like me have to use equations so that people like you will have something to fly.

I'm quite sure that you know that bumblebees don't fly but the equation crowd figured out that they catch the tip vortices on the backstroke.

The strength and performance of the design of that pair of barrel releases I wasted four hours making for you last fall was verified using equations.

And to waste a little more time (somebody who hasn't bothered to listen the first dozen times is highly unlikely to bother paying attention the thirteenth)...

Weak links do not necessarily break during lockout. Sometimes the glider slams into the ground first. A weak link will always break if the ground doesn't get there first.

I'd like you to provide a single QUOTE from this thread in which ANYONE suggested eliminating a weak link. Something a little more specific than the "You said..." vague accusations of which you and Marc are so fond.

By the way...

The best weak link protected two point gliders you tow are the ones using bridle systems I've designed and assembled. If the bridle wraps at the carabiner after failure of the primary weak link, the secondary at the bottom end blows instantly.

If your Dragonfly weak link pops and the lower bridle component wraps - you're out of ammo (see my first post).

Cragin,

A weak link does not have to and assuredly should not be "a bundle of threads tied in a loop" that you can "NEVER TRUST".

You can't make friends with or influence Jerry Falwell 'cause he don't need no stinking data, evidence, formulae, logic, common sense... He already knows The Truth.

Marc,

Look Marc! An ECC competitor who thinks a safety enhancement might be worth looking into.

Hugh,

In your case (two point) it's not really an alternate - just a supplement.

Since you're still towing in that configuration I'm starting to question my decision to talk you out of going with my full installation.

Look forward to seeing you.

Tad Eareckson - 2007/06/02 23:23:19 UTC

Correction -

With respect to the report:

Yesterday I was LUCKY that my weak link broke on my first launch...

Although there can be a couple of ways to interpret that passage a very careful reading reveals what Daniel Broxterman meant.

I had assumed that he was about to die but after an inquiry at Ridgely last weekend understood that getting involuntarily deposited back on the ground set him up to take advantage of a later lift cycle. The pop off was due not to the low level lockout onset I had envisioned but rather to some moderate turbulence and shouldn't have happened.

So move that one from the category of "Potentially Catastrophic" to the one which would normally have been "Moderately Annoying".

Jim Rowan - 2007/06/03 00:47:16 UTC

Why don't you give it a rest, Tad. You moved past the "Moderately Annoying" category several posts ago.

Tad Eareckson - 2007/06/03 10:41:24 UTC

Like I said before earlier...

Nobody's forcing anybody to read this thread. So if you don't have anything positive to contribute - and, based upon your previous posts, I couldn't possibly imagine that you could - ...

Tad Eareckson - 2007/06/03 14:52:18 UTC

'Nuther correction...

For "positive" in my previous post, swap "intelligent".

(In never proofread these things carefully enough.)

Tad Eareckson - 2007/06/03 20:06:46 UTC

Obviously didn't proof that one very well either.

Tad Eareckson - 2007/06/10 19:20:33 UTC

More corrections... Noticed redundancies in my first response to John and in my message to JR telling him to go fuck himself. Also found a "now" which should have been a "no".

Jim, thank you for illustrating more graphically and extensively than I could have possibly dreamt the point I was trying to make to Marc about just who is and isn't qualified to evaluate safety equipment.

I found quite noble your declaration about refusing to tow anyone not using a weak link, as bizarrely inappropriate and irrelevant to the discussion as was that comment.

Just curious though... Would you tow a new solo student using a two point bridle and a primary release mechanism you knew to be incapable of functioning?

Seems to me the latter scenario would be way more problematic but, hey, what do I know...

Darkened the ECC with my presence for a little evangelizing and free flying Thursday and Friday.

One of my first orders of business was to get an account of John Claytor's trike incident. Correct me if I'm wrong, John, but here's my shot at a summary...

Trike goes up like a rocket - fast and steep, glider starts oscillating, John's too busy trying to keep things under control to feel great about taking a hand off the wheel to actuate the release, weak link mercifully pops leaving him low and slow over Injun country with about one well executed survivable landing option.

My take...

I share - along with Bill Moyes and John Williamson - the conviction that if you have to move your hand to get to a release actuator you're inviting opportunities for trouble. There are systems available for one and two point systems that have no downsides other than expense.

I'd have liked to have sparred with John a bit more 'cause he has interesting ideas but time was limited and distractions were numerous.

Thursday evening I hit poor Victor with my spiel. Victor is an engineer, thinks and tinkers outside of the box, and is one of my favorite glider folk and there isn't much upon which we disagree but we butted heads a bit on this issue.

His position was that a flimsy weak link forces him to be extremely smooth on tow.

I countered that:

1. A weak link's function is not to punish one for being slightly human.

2. Virgin Greenspot loops pop all the time in glassy smooth air with the glider dead center, level, and stable for no reason whatsoever.

and neglected to amend that with:

3. It costs Highland Aerosports (and thus us) money and screws over the people in line.

A few minutes later Victor's Pulse was on the ground with a broken downtube. Woulda been perfect had it been someone I strongly disliked. (There was no line at that time of day.)

At a hundred feet in glassy smooth air with the glider dead center, level, and stable Victor's virgin Greenspot loop popped for no reason whatsoever.

The downtube, in fairness, died not as a direct result of the pop but a compromise of the landing to save some walking. There is no question, however, that the aluminum was trashed as an indirect consequence.

Anecdotally, there seemed to be lotsa pops during the competition and I heard of none desirable. The 2007 winner broke one in turbulence - I had been working on him but so far haven't gotten through.

Statistically insignificant but the two people flying competition (seventh place) and free who used shear links had no breaks. Sunny is using a 1.17 G bridle link for one point configuration, yours truly is using a shear link of about the same rating for two point.

On Friday Hugh graduated to one point towing and represented a fifty percent increase in local squid users. I noticed one somewhat disturbing yaw at about eight hundred feet and need to give him more trigger line slack (unrelated) but otherwise things went well. I wimped out on setting him up with a shear link 'cause I didn't want to hear about it if something bad had happened during a low level oscillation but next time he goes up after we next cross paths he'll be a full member of The Club.

Pat Halfhill checked out my systems, pronounced them way slick, and promised to post to this thread proclaiming me to be not a TOTAL asshole. He goes way back and it was very interesting talking to him. It seems that Steve is only the second reinventor of the squid concept. I had learned a year ago that the eastern Europeans had been using a bite controlled multi-string a decade and a half before and Pat informed me that Rob McKenzie had introduced a version for truck towing.

I'm going out on a limb and stating that the critical mass of gray matter exists and this shear link concept will displace the fuzzy fishing line crap. The implementation can take one of several paths.

First some background...

Last season one of the Ridgely Dragonflies had a mast which developed a crack in the mast at the bolt which anchors the top aft end of the tubing which defines the leading edge of the vertical stabilizer. As this crack formed at the aft half of the circumference I'm thinking that it has everything to do with flexing as a result of drag produced by rudder control actions and nothing to do with tow line tension.

The double loop of Greenspot that has always been incorporated in the Dragonflies' bridles limits tow line tension to about 400 pounds. A heavily loaded Talon 150 can take a 700 pound tension and remain within specs (2 Gs).

I, again, am recommending a 1.4 G universal standard 'cause that's smack dab in the middle of the safe range, thus allowing the widest range of tolerances, and is plenty enough to eliminate virtually all undesired breaks. That brings the top solo tension down to 500 pounds.

If we can boost the Dragonfly weak links we can bring the stuff on the gliders up with less fear of getting stuck with the rope. But weak link breaks at either end should be so rare that that should be an issue hardly worth considering.

The tandems are their own. They seem to do OK with the same double loop of Greenspot on the ends of their bridles. As things are they seldom, if ever, get the rope 'cause the tug bridles are relatively long (thus transmitting less tension) and the weak links are not subjected to wear.

It would be great for everyone to know his flying weight. Hop on the bathroom scales with the backpack, look up or weigh the glider, do the arithmetic. I can also get a way more accurate than necessary total on site with a hydraulic cylinder under a limb of one of the maples by the pavilion.

For anyone towing one point I can, for maybe fifteen bucks, provide an appropriate shear link. The lengths of whatever you have coming off your port and starboard AT loops (on your harness) must be equal. Identical twin barrel releases are common and easy.

For two point towees I could provide a bridle system similar to mine 'cept these things are tedious to punch out and it's not worth it for something that's gonna get chewed up by a spinnaker shackle. That leaves Tim Hinkel and the former John Claytor as the only other candidates. Sooo...

Plan B. I provide individual 1.4 G Tow Line Integrated Shear Links for around forty bucks apiece. Seems like a lot to replace something requiring a knot in a penny's worth of material but it's only about eighty percent of what a Tost assembly sets you back and if it lets you get up to altitude during prime time and maybe saves you a downtube ( especially if its one that goes on a Talon and gets folded after a pop coming out of the cart a la Denis Scheele - 2002/09/28 ) it starts sounding pretty good. For the time being if it fails for any reason not involving an Exacto knife I'll restitch the parts for the price of a report of what happened.

The recipient swaps his Greenspot for loop of 205 or 350 leechline which will survive a bit of spinnaker shackle abuse before it becomes an issue and takes any redundant weak links out of the system.

Upon the landing of the tug that just hauled you up, the glider launcher (e.g., Bob) removes your weak link from the carabiner and tosses it in a box after launching the next glider.

Hopefully this will become standard practice and you can trade your shear link to the flight park for a couple of tows and just request your color code as you near the front of the line.

P.S. I've been rereading some archives and I noted that Robin caught a lot of posthumous flak for using a doubled loop of Greenspot. Even if he was at the bottom end of the range of the smaller AirBorne C2 the worst he would have been doing was to have pushed the USHGA specs. The spinnaker shackle hang up was what killed him - and we've had those - up high anyway - at Ridgely.

Tad Eareckson - 2007/06/19 12:29:47 UTC

The Calf Path
1895
Sam Walter Foss
1858-1911
Public Domain

I.

One day, through the primeval wood,
A calf walked home, as good calves should;

II.

But made a trail all bent askew,
A crooked trail as all calves do.
Since then three hundred years have fled,
And, I infer, the calf is dead.
But still he left behind his trail,
And thereby hangs my moral tale.
The trail was taken up next day,
By a lone dog that passed that way.
And then a wise bell-wether sheep,
Pursued the trail o'er vale and steep;
And drew the flock behind him too,
As good bell-wethers always do.
And from that day, o'er hill and glade.
Through those old woods a path was made.

III.

And many men wound in and out,
And dodged, and turned, and bent about;
And uttered words of righteous wrath,
Because 'twas such a crooked path.
But still they followed - do not laugh -
The first migrations of that calf.
And through this winding wood-way stalked,
Because he wobbled when he walked.

IV.

This forest path became a lane,
that bent, and turned, and turned again.
This crooked lane became a road,
Where many a poor horse with his load,
Toiled on beneath the burning sun,
And traveled some three miles in one.
And thus a century and a half,
They trod the footsteps of that calf.

V.

The years passed on in swiftness fleet,
The road became a village street;
And this, before men were aware,
A city's crowded thoroughfare;
And soon the central street was this,
Of a renowned metropolis;
And men two centuries and a half,
Trod in the footsteps of that calf.

VI.

Each day a hundred thousand rout,
Followed the zigzag calf about;
And o'er his crooked journey went,
The traffic of a continent.
A Hundred thousand men were led,
By one calf near three centuries dead.
They followed still his crooked way,
And lost one hundred years a day;
For thus such reverence is lent,
To well established precedent.

VII.

A moral lesson this might teach,
Were I ordained and called to preach;
For men are prone to go it blind,
Along the calf-paths of the mind;
And work away from sun to sun,
To do what other men have done.
They follow in the beaten track,
And out and in, and forth and back,
And still their devious course pursue,
To keep the path that others do.
They keep the path a sacred groove,
Along which all their lives they move.
But how the wise old wood gods laugh,
Who saw the first primeval calf!
Ah! many things this tale might teach -
But I am not ordained to preach.

Thanks again, Garrison.

Tad Eareckson - 2007/06/27 12:59:53 UTC

Had an interesting experience on Sunday afternoon.

Had a discussion with Christy shortly before going up about why anyone who tows two point REALLY needs a secondary weak link.

The tow was bumpy enough that I figured it would be OK to hit the button at 1600'. I was under a good bit of tension in the lower region of a column which would take me up the next twenty-four hundred at a very steady climb averaging 582 fpm and had a good news/bad news sorta event which commenced with the top end of my primary bridle solidly tying itself to the tow carabiner.

To help understand what I'll be talking about check the Primary and Secondary Shear Links photos at:

http://www.flickr.com/photos/aerotowrelease/

The bad news... while any two point bridle can wrap this flight was likely good evidence that my current design is more prone. The lack of a smooth taper was the issue in this case.

I have not recommended this bridle design to anyone using a spinnaker shackle as the primary release mechanism 'cause said hardware will chew up the eye of whatever is engaging it. 'Round these parts the only eligible candidates are Tim Hinkel and yours truly and the latter is currently the only one concerned.

On to the good...

I'm using 240 and 288 pound weak links at the top and bottom ends of my bridle respectively (and my secondary bridle is a 525 pound bridle link).

I'm now connected to the tug a skipped heartbeat longer than I had planned and my brain is going into barrel mode when the secondary weak link blows and I'm off and climbing.

Although it absolutely WILL fail after a primary gives up the ghost I really wasn't expecting the secondary to go under these circumstances. Guess the little jolt was enough to do the trick.

I watched the bright white bridle long enough to determine that it was still secured to the towline and got it and a report from Bob after a nice flight which took me to a max of 5396'.

Anyway, it was very rewarding to see that there is a good chance that that system will auto release in a more dangerous scenario.

Last season Victor, I found that afternoon, had a bridle wrap and secondary weak link failure.

Sunny, also that year, had a wrap with a tandem at release and was in instant one point mode. The combination of the tow line dropping relative to the glider and the harness being pulled forward caused the twin barrel releases to be dragged across the basetube. They opened simultaneously. Although both primary and secondary bridles were lost, that serendipitous auto-safety was kinda cool.

I was pleased to note that Victor had doubled his Greenspot but had to chew him out for maintaining a single loop on his secondary bridle. Although on a Spectra bridle a single fails at about 140 and a double 202, the geometry of the system adds some stress to a weak link on a secondary bridle and one can get killed pretty fast if:
- the trim point on the keel is forward;
- the bottom end goes first;
- the bridle wraps; and
- the primary weak link holds.

You can't go wrong having weak links of equal strength installed on the top end of your primary and on either/both end(s) of your secondary bridle.

That double loop on Spectra, by the way, is a much better one-size-fits-all option for two pointers than the single standard. It keeps everyone from two (Karen) to four hundred pounds within specs.

It didn't take Steve Padgett much convincing to put his primary bridle through the end of a 378 pound shear link. His previous flying day at Ridgely had earned him one successful tow to altitude for three efforts.

Hugh's two point tow on Saturday was safetied with the same link. Henceforth he is planning on towing one point using a 420 pound bridle link.

Steve Kinsley was set to go with the same bridle link but needed his one-of-a-kind one point system adjusted first. He'll be permanently on board after we get that taken care of.

I managed to blow most of PK's resistance to hell and believe he will shortly join the club of folk who want to be in charge of their separation altitudes.

Correction...

The crack was on the leading, not, as I believed, trailing face of the Dragonfly mast so my rudder drag fatigue hypothesis had to get tossed. So maybe tow stress is the culprit but I'd still like to see if it would hurt anything to up the front end weak link strength by about half.

Off topic...

As everyone with the ability to look sideways and/or down already knows - the farm that used to be across the road from the west end of the runway is being replaced by an industrial park. Just realized the pair of Kestrels we've always had nesting in the vicinity has been nowhere in evidence this year. A connection? Do ya think? Those beautiful little birds are getting wiped out from the eastern third of the country along with grasslands and everything that depends on them.

Marc Fink - 2007/06/28 11:45:55 UTC

I'm sorry, I can't resist--but it finally dawned on me, you are truly "the missing link!"

Brian Vant-Hull - 2007/06/28 18:14:35 UTC

Can't you see this has become Tad's personal blog? You're, like, totally destroying the experience.

Tad Eareckson - 2007/07/02 12:36:22 UTC

Hi Brian,

I was very happy to see your name linked to the previous post 'cause it had been four weeks since I had a respondent typically encumbered by the thought process. Then I clicked and got a toned down version of Marc/Chris/Jim/JR. Was kinda hoping that I was gonna get a comment on my response to your question of 2007/05/22.

So let's say it's a blog. Isn't that pretty much what constitutes the bulk of this forum? Folk reporting on flying experiences, incidents, hang gliding related points of interest?

I get occasional comments along the lines of "We're sick of it!" (Royal "We") but then I look at the ol' Views counter. What was it when you posted? About thirteen hundred? All time record for the forum maybe?

If you're not interested - don't click. How much bandwidth does the whole thing chew up? One small photograph?

Just about the whole freakin' planet is using weak links which are, at their best, about half as strong as they should be. Light bulbs have just switched on for half a dozen local pilots. That's worth the bandwidth. If something glows for someone cruising the archives many years from now - it's worth the bandwidth.

Dan (Tomlinson),

I was just rereading your 2007/05/21 18:18:18 UTC post and managed to focus on something this time.

You stated that weak links failing to kick in when needed have often led to catastrophic consequences. I know of no such incidents. Can you cite any?

Brian Vant-Hull - 2007/07/02 21:28:24 UTC

Tad - hey, I'm in the middle of the mind numbing task of combining a huge reference list and getting them all in the same style...can't handle any intellectual effort right now. Sorry, I know you were expecting great things of me.

Anyway, it's clear you've spent more time than any of us thinking about towing apparatus, and that has to be a good thing. Any reasonable person has to admit the weak link strength should scale with tow mass. The exact numbers required is quite a bit more subjective.

People are gonna lob grenades. If you lob them back you wipe out more than the person who threw it, and your prospective audience evaporates. Just look at the last page of this thread, and your posts right before the deafening silience.

I think in the last week or so you are finally (in very small steps) taking on the mantle of the long suffering prophet of a good idea, one who will quietly absorb the attacks and keep plodding away. If you stick with this approach it will eventually work. People erect churches to patiently suffering dead guys. Or if you don't like religion look at Jackie Robinson. But it takes patience and forebearance. If you lose the forebearance even for an instant it will take more patience to rebuild the audience.

And don't mind the grenades...it's part of the process.

Cragin Shelton - 2007/07/03 05:43:56 UTC

Weak Link Failure with Catastrophic Conseequences

Tad Eareckson wrote:Hi Brian,
>>SNIP<<
Dan (Tomlinson),

I was just rereading your post of 2007/05/21 and managed to focus on something this time.

You stated that weak links failing to kick in when needed have often led to catastrophic consequences. I know of no such incidents. Can you cite any?

Bill Bennet

Tad Eareckson - 2007/07/04 12:00:22 UTC

Hi Brian,

Thanks for the note.

You may be right about retaliatory grenades but I don't toss them until all efforts at rational discussion have failed. I decided that some bridges were in major need of incineration and have no regrets so far.

And I'm hoping that other readers are sharing some of my unhealthy delight at watching folk pump nine millimeter slugs into their feet.

Nah, not fond of religion. Push it to its "logical" conclusion and you get Crusaders, suicide bombers, and witch burning. Push logic, math, science and you get "Here's what's gonna happen if we do this."

Jackie had to start at an extremely low nadir. It's possible I have enough momentum going now to make an occasional charge into the bleachers but I'd rather have the 25+10=35 cops control the abusive drunks.

Yeah, things got pretty quiet - 'cept for yours truly of course - but I'm pretty sure that's 'cause no one wants to touch this with a ten foot pole. Yours truly isn't having much fun touching this with a ten foot pole either. I do, however, greatly enjoy the inputs and correspondence with folk with whom one can carry on a civilized conversation - about 6.3 relevant respondents to the point of your post.

I may or may not have had some audience evaporation but this keeps getting read. Even when it gets buried in the chronological order the numbers keep creeping up. I'd like to believe that the people who are reading and, perhaps, rereading are also thinking.

With respect to picking numbers...

Once one gets what James Freeman is saying in the link Danny posted things get real easy.

I'm gonna lose ten pounds to make the math easy and we're gonna say that the cross spar of my 300 pound glider buckles at six Gs (conservatively). I'm gonna be a wimp and require a two G safety margin. I put a 900 pound weak link on the end of the tow line and I pop at four Gs (one provided by the glider, three by the link). My glider is still intact and I'm perfectly happy.

But I don't need a three G weak link 'cause if the glider has loaded up to much more than two G's the tug is probably nowhere near where I'd normally expect to find it and I'd just as soon be off tow anyway.

But... I'M NOT PICKING THESE NUMBERS (much - see comments on USHGA below)! THESE ARE FAA AND USHGA NUMBERS!

I'm just saying use the number dead center in the middle of the safety range defined by these entities.

Elaboration...

USHGA has problems. One of them is the spelling of bridle. Here's another...

"(5) Inadvertent weak link breaks at low altitude can lead to accidents."

But they only specify the same two G upper limit that the FAA uses for sailplanes and say NOTHING about a lower limit.

So you can use the string off your tea bag as a weak link - 0.01 Gs let's call it. You will be perfectly safe until a dust devil comes along and sucks you off the cart.

As you start upping that number things will, at some point, start getting dangerous. You're going to see a lot of downtubes and an occasional arm get broken.

As you approach 0.8 Gs things start getting safer again 'cause your chances of getting to a hundred feet go way up.

If you use a weak link in the middle of that 0.8 to 2.0 range you're never going to have a weak link break.

Five months ago I was ordering a couple of Tost weak link assemblies from Wings and Wheels, a sailplane supply place in Lakewood, New York. Tim Mara apparently doesn't sell a whole lot of those 'cause folk on this side of the Atlantic generally use the tow line as the weak link. He had asked one of his customers for some feedback on the Tost links. The response was, "Well, we've never broken one."

I thought, "Yeah, they've never broken one. Bull's-eye!"

More with respect to weak link strength...

Chad, Sunny, and Adam all thought that the Greenspot loops WERE almost precisely in line with the strength I'm recommending for gliders around my weight.

The hypothesis was...

130 pound string, tie a Fisherman's Knot to form a loop, that weakens it, but you isolate the knot in the middle of a Double Lark's Head.

Single loop - 2 strands times 130 equals 260 pounds. Double - 520 pounds.

Sounds reasonable.

Then I broke out the bathroom scales (and later built a test rig). Nope.

Single - 140. Double - 200.

So all I'm saying is we should be doing what we thought we were doing.

Cragin,

Nope.

That glider hit the runway 'cause the release at the back end of the line wasn't actuated and the one at the front didn't work. The airframe didn't snap before impact so the weak link was not an issue.

I'm gonna go out on a limb here and state that it is physically impossible for a glider to need a weak link when it is within striking distance of the ground 'cause you there's no way for you to build up enough loading to stress the frame - even if you wanted to. (I stand ready to be shot down by an aerobatics pilot but let's at least think about this one.)

This recently in from Christy...

Bill (port) had the release actuator.

How 'bout we consider the ramifications of the Pilot In Command (Mike) not having access to the brake pedal.

Marc Fink - 2007/07/05 11:58:41 UTC

I remember Bill's accident and talked to a couple of people that were there at the time of the accident--and as I recall nobody had a vantage point good enough to make any conclusions as to the real cause of the accident and what really transpired. How can anyone who wasn't even there make any meaningful conclusions?

Tad Eareckson - 2007/07/06 12:50:20 UTC

Cragin Shelton - 2001/08/08 09:03:01 UTC

On Trusting Weak Links

Reading Joe's last item in the lockout thread prompts me to point out a consideration in the discussion:

NEVER TRUST A WEAK LINK!

Expect two things from your weak link:

(1) It will break unexpectedly at the most inopportune time, with no warning adn no indicaiton of a flight problem.

(2) It will hold strong and fast whenever you move into a lockout. You must never plan or expect on a weak link break. It may well not break when you fly with that attitude. As Joe said, if your situation is new to you and not right, get off tow!

I have never had an instructor use those words to me, but all towing instructors I have worked with have given that message in some form. Pagen & Bryden address it clearly in _Towing Aloft_.

This issue is critical for all tow pilots, but requires special emphasis for truck-towing, or any system that uses tension control. Any line, including the weak link, can hold together in much stronger forces pulled out along its linear axis with gradually increasing force, than whne subjected to a quick change in force. Weak links work best when popped. Tension systems, which include all pay-out winches, are designed to reduce the sudden changes in force. It is fairly easy for a glider on a payout winch with tension control to gently move into a lockout condition and never stress the weak link sufficiently to break.

So, to repeat: Never trust a weak link. Be prepared to fly off tow in a surprise break at all times when attached, and be prepared to hit the release at all times in case of a surprise attitude change.

Paragraphs 5 and last sentence of Paragraph 8 - Solid.

Paragraph 7 - Solid with respect to tension limiting systems. Since Greenspot is so monumentally unreliable anyway there's not much point in discussing popping.

Paragraphs 2 and 4 and first sentence of Paragraph 8 - Solid with respect to virtually the entire culture at the time but crap locally as of whenever it was last year that I noticed a real linear relationship between number of stitches and strength.

And I'm gonna predict that my weak links don't care about the speed at which stress is applied. Retains its integrity up to 239 pounds - explodes at 240.

(The author, by the way, had the opportunity to take a look at the advance which would have allowed him to spend more time thermalling and less straightening downtubes and waiting in line but was quite certain that what I had wasn't worth readjusting the focus of his vision.)

There is a major consistency problem with Paragraph 5 and the offering of the Bill Bennett/Mike Del Signore crash as an example of the use of an overstrength weak link having catastrophic consequences.

OK - Let's say that there was an overstrength weak link as alleged. Bill, Mike, Double Vision, harnesses, parachute - 500 pounds? Maybe less but close enough and an easy number.

To put that glider out of USHGA specs would have taken a 580 pound weak link on the top end of the two point bridle. In terms of Greenspot that's nearly five loops. (Yeah, I know - Bullshit! But let's go with it...)

Lockout. Number of survivors - Zero.

Now let's look at Mike Haas...

Single loop of Greenspot which, by now, everyone with an IQ equal to or greater than his Hang Rating agrees is - at best - hovering around the bottom end of the safe range.

Lockout. Same number of survivors.

Conclusion - Weak link G ratings were totally irrelevant.

On to the "inexperienced tug pilot who dumped power when he shouldn't have".

If you're doing your job on the back end of the string the tug pilot can't kill you. If you fuck up someone on the front end may be able to salvage your ass but that's gravy.

I once saw a masterful job of a winch operator very probably saving a life. Well... I didn't actually see it 'cause at the moment I was running for mine 'cause that lockout was due to terminate in about two seconds at the precise spot at which Ray Dunmyer and I were standing. Lawrence Battaile had popped off the beach with his right wing stalled and Jonnie Thompson gave it the gas and pulled him back and up. That was one situation in which the failure of a marginal weak link would not have made the day go better.

Let's try to kill a tow pilot. He's pretty safe on the ground so you need some sort of energy. You can get that with wind or occasionally hay and oats but you almost achieve that goal by setting fire to gasoline. You transmit that potentially lethal energy to the tow pilot by means of a string but your wily prey always has the option of severing his relationship with said cordage.

We know precisely what caused that accident - same thing that causes virtually all tow accidents. The glider stayed on tow too long - it hit the ground still connected to the tow line.

Too long may be defined as something on the order of a second or two after liftoff if the bridle is routed under dolly tubing but it's usually something of much more comfortable duration - as was the case in this situation.

There are several excellent and reasonably consistent eyewitness accounts of this accident. We know what happened. It would be nice to know why some of these things happened but that information is secondary.

I'll give it my best shot - They were too slow. Tried to milk it, started losing control, tip stalled. Shoulda pulled the basetube and pin then gotten back on the cart.

Anybody ever notice that out of zillions of opportunities at Ridgely we've never seen anything remotely resembling that scenario behind a Rotax 914?

Tad Eareckson - 2007/07/15 22:06:51 UTC

Sacred Cow in crosshairs...

Some AT related excerpts from Towing Aloft...

Page 54

A weak link is the focal point of a safe towing system.

Speed controlled towing is when the speed of the device doing the towing is maintained at a reasonably constant value. Controls, such as the throttle, are used to keep the speed of the tow vehicle or tow winch operating at a constant speed. Towline tension can vary dramatically in response to thermals, sink, pilot corrections, etc. Aerotowing is clearly in this category as the tug needs to maintain a minimum speed to prevent stalling. Many of the early towing efforts of the '70s where the vehicle drove at a fixed speed would also fall into this category of towing. Weak links very clearly will provide protection from excessive angles of attack, high bank turns and the like for this category of towing.

Page 53

A weak link is required that will not break needlessly in response to moderate thermals, or pilot inputs, yet, will break at a low enough point to avoid disaster or excessive pilot panic.

For aerotowing operations, a weak link breaking strength equal to 80 to 100% of the total flying weight--the weight of the pilot and glider--is a reasonable starting point.

Page 60

Three recent tandem aerotowing accidents have occurred--one fatal. The common thread in all three was a lockout and the use of a much too heavy weak link. Tandem gliders are much less responsive than smaller gliders and the pilot in command often has a less than ideal position on the control bar. The situation shouldn't be compromised by an over-strength weak link.

Discussion/Assault...

Maybe it is the focal point but it shouldn't be. You actually have two legitimate focal points and they can trade in positions of prominence over the course of the tow but Numero Uno is almost always the release actuator (this assumes that the mechanism engaged by it has a good chance of actually functioning). The basetube slides to the fore around the time you're saying bye-bye to the dolly in a normal flight and in the event you're low, banked, and climbing or getting pulled out of a bad situation by your driver.

With respect to the last sentence of the second paragraph...

Yeah, they'll ultimately provide that protection but you can easily be dead - or effectively so - before it kicks in. You can find yourself in some very creative combinations of attitudes while still connected to the tug courtesy of something quite understrength.

Page 53...

Depends on what you mean by disaster. Yeah, it absolutely can prevent a cross spar from buckling. But there is no way it can guarantee that you won't slam into the ground on a hitherto pristine glider or serve to maintain your emotional stability. They got pharmaceuticals for the latter issue but there always seems to be some caveat about driving and operating machinery on the label.

and...

Yeah, 0.8 to 1.0 Gs is a good starting point. The middle of 0.8 to 2.0 Gs is a really good finishing point.

And many of us, including Victor and yours truly, have demonstrated that the loop of 130 pound Miracle String described elsewhere in the chapter is reliable to no more than about 125 pounds of tow line tension - that translates to 0.4 Gs for the two aforementioned individuals. (Gee it's great towing up on a good day without having my heart in my throat the whole time as had always been the case previously.)

Page 60...

I'm guessing the fatal accident referenced was Bill and Mike. Nah. There isn't a weak link in the galaxy that's gonna save you from a low level tip stall.

I'm working on collecting and organizing information from that wreck (there are some missing pieces) but, for the time being, you can take my three sentence assessment from my previous post to the bank. That is EXACTLY what happened. We figured that out at the time but I had forgotten some of those discussions.

If anyone has any information that didn't come across the wire I would greatly appreciate knowing it.

Just looked into purchasing a set of Hang Gliding magazine DVDs but they're backordered till January (just how long does it take to burn those things anyway?). Would also appreciate a copy of the report of the 1996/07/25 accident.

Also, I'm still desperately seeking an account of a single incident in which a weak link break was a desirable component of an aerotow - meaning shit was happening so fast that the pilot had no reasonable opportunity to actuate a reliable release mechanism.

Let's take a look at...

Van Sickle's Modern Airmanship, Fifth Edition
1981

Page 793

Since improper technique by the winch driver or carelessness on the part of the pilot can impart many g's load to the aircraft, the FAA requires that a weak link be used in the launching cable at the aircraft end. It should break with a pull of about twice the weight of the glider.

Page 795

The tow hook on the airplane is made so that the tow pilot can release his end in an emergency, as can the sailplane pilot...As in other types of launching, a weak link is required if the towline's breaking strength is more than twice the weight of the sailplane being towed.

Three of those four sentences tell you most of what you need to know about weak links.

Note: That text states that (then) modern sailplanes can withstand 8 to 12 Gs so they're a bit stronger then hang gliders. Strike my previous reference.

Update...

I was really bothered by my 2007/06/24 bridle wrap and went back to the drawing board. The new design has been up four times and I'm very happy with everything about it except the enormous tedium of hand stitching three ten foot lengths of 3/32 inch line together. The result, however, incorporates shear links at both ends, is virtually totally uniform in thickness, and is so stiff it would by difficult to knot it to a carabiner by hand.

Off topic...

At least one Kestrel was able to withstand the bulldozing so far. The 06/24 morning fog was too thick to get a gender but a representative of the right species was making a lot of noise at the top of the AWOS tower. Also, speaking of falcons, look for Peregrines as you're crossing the last two bridges before Kent Island en route to Ridgely. They've been nesting on the Bay Bridge for decades but a pair managed to fledge an offspring on the Severn River Bridge this season.

Chris McKee - 2007/07/16 02:39:14 UTC

With all the space you're taking up on this website, maybe you should think about joining CHGPA so you can help pay for this service. I believe this is considered a benefit of membership dues within the club. At least kick in your yearly membership dues to support your use of this as your public forum! Just something to think about ... its the right thing to do.

Tad Eareckson - 2007/07/17 12:29:11 UTC

First off, yeah, Chris, I do know that you are quite sure that this is nothing more than an exercise in taking up space and unworthy of reading and responding to. I'm guessing that you got into no more depth in my previous post than noting its length but if you've made it this far in this one - I was wondering when you were gonna take a look at all that empirical data you were demanding in your previous.

Second, never in the nearly twelve year history of the various forms of the local glider list server/forum has it ever been related to CHG(P)A membership nor (someone correct me if I'm wrong) in any way supported by dues. It's mostly been fueled by the blood, sweat, and tears of volunteers such as Brian Hardwick, Dave Green, and Mark Cavanaugh (did I miss anyone?)

Third, you've posted half a dozen times on this thread and each of those has come with a pair of images. Those twelve little pictures have eaten up a bit less than twice as many ones and zeros as the combined text of all messages to date - including this one. So let's not get too self righteous about bandwidth and storage.

Fourth, I'm a member of two other groups (towing and tugs) and they're both free too.

Let's dispense with the numbers now...

Along the lines I wrote in a response to you five years ago - I was a CHGA member from around 1982 through 1999. Towards the end of that period I did a massive amount of work running Hangola and serving as Secretary for four years (I was actually listed as Secretary for a fifth but I won't count that as by the end of the span I had imploded and didn't do shit).

In the same general time frame I was realizing, as Ralph did some years later, that it was totally insane wasting a good chunk of one's life transcribing and editing digital information for paper format and distribution, I had also burned out on the whole mountain/driving/shuttling/hike-in/ridge soaring/site maintenance scene.

Then early in the 1999 season Highland Aerosports suddenly dropped out of the sky and landed way closer to my back yard than I could have possibly dreamt. (Now if only someone could find a way to grow a hundred foot dune at Sandy Point State Park...) At that time all of my eggs went into that basket and that's where I transferred my volunteer energies.

If al-Qaeda manages to nuke Ridgely I'm gonna have a real hard time generating the enthusiasm to roll to the ridges (not that there's anything wrong with that). The AT environment has always been where I've wanted to fly - since a decade and a half before that mode of getting airborne was halfway practical - and I'm now way too spoiled to entertain much thought of going back.

I perform a lot of little chores from which folk benefit - directly or in- - that don't get noticed much. When you hop on a launch dolly I'm probably the reason your tires don't flatten to the rims. There's a bit of glass and aluminum that the crew doesn't have to move from the picnic tables to the dumpster 'cause it ends up in my recycling bin (Erica finally gave up in frustration after several efforts at organizing recycling 'cause hang glider pilots - collectively - don't give a rat's ass). I've probably saved the airport thousands of dollars of electrical bill 'cause I'm one of about fifteen or twenty Americans who realizes that most light switches also have an "OFF" position.

I've ensured that there are - so far - half a dozen Ridgely flyers that are never gonna gum up a line while they try for a second (or third) time to get to release altitude.

The ratio of time I've spent developing, fabricating, testing, documenting, and illustrating tow equipment to my airtime is astronomical. (Marc is an excellent example of why only a small portion of these advances have been adopted on a very small scale - "It can't be any good, 'cause if it was - we'd be using it!")

Towing Aloft represents a lot of effort of compiling, illustrating, explaining glider towing issues. It's a valuable resource and I appreciate it. Dennis and Bill sell it, we buy it. A lot of the information is very good, it's riddled with mistakes, some of it is crap (some of the latter category comes better to light with nearly a decade of extra experience, some was clearly identifiably so while the ink was still wet).

So, Chris, I fork out a not inconsiderable penny for materials and equipment, lose a few assemblies to folk who never quite get around to reimbursement for so much as materials cost, do all this work, analysis, and correction and make it available for free (and, contrary to your assessment, lotsa people who aren't forced to actually read it), get rewarded with a lot of stupid abuse, and you're not happy unless I go even further into the red? If you're trying to make me squirm with a guilt trip you gotta do way better than that.

Update...

Saturday afternoon I was able to get my grimy little hands on the latest version of Tim Hinkle's two point release. As I've told him - I'm not a fan of slap-ons. I like to see (actually, not see) control cables INSIDE the tubing... But if you want a one anyway - this is a thing of beauty. Very simple, elegant, mechanically efficient, and it's gotta be brutally strong. If you're considering acquisition of a spinnaker shackle based assembly... Don't.

I had asked him to put an assembly together for me before I had seen this state of evolution. When I get one I can take home I'll get some photos up.

Gary Devan - 2007/07/17 13:33:25 UTC

Dough!

Gary Devan - 2007/07/17 13:57:19 UTC

(tadd, the intention, to be sure, was to put a smile on your face, as well as any one else.)

Hugh McElrath - 2007/07/17 14:08:02 UTC

Tad,

Let me know what I owe you for the release.

I direct your attention to the "Manquin Sunday" thread. (Should rightfully be on the PG side.) Would welcome your analysis of rigs for PG scooter/truck towing. Maybe the weaker weak link is appropriate here?

Tad Eareckson - 2007/07/17 16:40:10 UTC

Nah, that wasn't directed at you, Hugh. We just recently got you properly adjusted and on your way and I hadn't asked for reimbursement. A one point assembly, complete with a pair of those rather pricey Wichard Snap Shackles, that disappeared into the wilds of Spring Mills, Pennsylvania a year ago has me a bit pissed off however.

And I do appreciate you sticking through the adjustment issue and posting that nice little review. (I have thought and am thinking more about a magazine article.

Yeah, I had been reading the discussion between you and Matthew and, of course, my ears pricked up at the first mention of the term "release".

I tend to shy away from paragliding issues 'cause I only have the cranial capacity to be obsessive/compulsive in one field but if I sat down with someone who understood bag flying and towing issues I might be able to come up with something useful in the spillover realm.

I do, in my little collection of tow oddities, have a Keller/Koch two stage release. That flavor is best employed for hang glider stationary winch launching and step towing but the PG model is just the same piece of hardware configured for one stage. No reason whatsoever that the second stage of my release can't be ignored and you're welcome to take it for a spin.

It's also rather elegant but kinda overbuilt and I've come up with an equally good and infinitely less massive HG solution - pretty sure part of it would work for pipeless.

With respect to weak links...

"Uprating" is only part of what I'm pushing.

While I'll cling to my stand of 1.4 Gs like an octopus my concept can be used to reliably get you down to about half the tow line tension of what a loop of Greenspot on the end of a bridle is SUPPOSED to give you.

PG weak links? No problem. Anything from about 126 up to around 600 pounds. Much above that and I have indications that reliability starts going to hell. Go with Tost for the heavy stuff.

Hugh McElrath - 2007/07/17 18:18:33 UTC

Well, I did have some experience helping Dave [insert last name here], an experienced competition PG pilot and instructor, who was working with Bobby Bailey and his unique biplane Dragonfly to try and aerotow a paraglider down at Quest. They were experimenting with twice-as-long towrope and having the Dragonfly launch into a turn, so that the PG could turn inside and not have to go as fast. Dave was quadrupling the weaklink and it was still breaking quite consistently. A weak later, he posted that he had successfully towed to 3000+, but I have heard no more about PG aerotowing and I'm told Bobby removed the second set of wings from the Dragonfly...

Matthew Graham - 2007/07/17 18:59:48 UTC

PG Towing

see--
http://www.towmeup.com/bridle1.html

Tad Eareckson - 2007/07/18 16:57:17 UTC

Sorry, Gary, I didn't catch that you had posted a second time before my clicked "Submit" for my previous. I did admire the creativity of the little image but no one really wants to admit that Homer is a caricature of us. Do me as Bart or Lisa next time. He's more of a hang glider personality and has actually been up tandem before, she's way more likely to make a doomed attempt to organize a recycling effort and kick butt at the science fair.

OK, I opened up my copy of Towing Aloft and familiarized myself enough with paragliders to dip a toe into the water. (Put the magnifying glass on the photo on Page 45 - two stage Keller/Koch being used as a one stage.)

And, yeah, I became acquainted with TowMeUp last winter. There's a lot of good information at that site.

The high speed trim assist and auto-release configuration both look pretty cool. The former is quite analogous to sliding your two point hang glider release attachment point fore on the keel.

The split bridle also gets good marks but I don't think that boat towing is an issue around here and that concept is essentially incompatible with the auto-release, although you could combine them at the expense of a small extra step of operation.

My tow line integrated shear link (http://www.flickr.com/photos/aerotowrelease/) would fit very comfortably onto the end of a paraglider tow line, 'cept you wouldn't need or want the larger thimble - pop it out and use the little RF2180 on both ends.

I prefer though, as with hang gliding, to leave the weak link with the glider so nothing either delicate or expensive need get dragged after release and if I were gonna put something together...

I'd be inclined just to use a couple of barrel releases with a bridle link between them. That would still cost the auto-release capability (although you could get it back my jumping through a couple more hoops) but leave you a split bridle and let you keep the weak link.

The barrels would have to be comfortably accessible in a worst case scenario - low tow line angle - yet be far fore enough to allow for attachment of the trim lines to the bridle halves. Might have to go to remote barrels (see the pictures again) if that geometry doesn't work.

On a hang glider you can actuate the primary release of a two point system with both hands firmly planted on the steering wheel. On a paraglider you have to move your hands with respect to the main structure of the aircraft to make it go where and how you want so that's a bit of a problem if you want to keep doing that and release.

I'm thinking it would be pretty easy though, to run a remote barrel lanyard up to your teeth so you can simultaneously control your flight and terminate the tow.

Pretty good way to configure a hang glider platform launch system too, eh what?

Again, I don't want to shoot my mouth off too much about PG issues but you have Towing Aloft recommending 0.75 G weak links and Hugh talking about quadrupled weak links popping with no consequences to the aircraft. I gotta extrapolate that the principles are the same. Use the release to release and the weak link to prevent the canopy from being overloaded.

Gary Devan - 2007/07/18 23:09:58 UTC

fair enough. more so even.
umh, while i'm still out here 'at the edge' . . . 'taking advantage of your good humour by being forward here . . . you've always been a creative writer - but it sometimes helps, when writing, to maybe 'breathe' more often. just a small thing.

Marc Fink - 2007/07/19 06:54:41 UTC

Hugh McElrath - 2007/07/17 18:18:33 UTC

Well, I did have some experience helping Dave [insert last name here]...

Dave Prentice. Aerotowing a paraglider has nothing to do with other conventional methods of towing paragliders.

I've used and sold many "tow-me-up" bridles--but they can "stick" to an in-line weaklink occassionally by virtue of a thinner line binding on the thicker material. This can be easily shaken off with a little weighting--but it's enough to keep the towline with you if you're not careful. Nowadays, I recommend looking at the bridles made by Critterware.

The reason weaklinks break in paraglide towing at the start of the tow is almost always due to excessive tow force relative to a high angle of attack of the canopy (hence the "accelerator" which is intended to lower the angle of attack while under tension).

Bridles also need to perform reliably in reverse inflations.

As annoying as it may be to experience problems with weaklinks towing a hang glider--you can easily end up getting seriously hurt or killed with a towing malfunction while towing a paraglider.

DO NOT become a test pilot for paraglide towing equipment unless you are very experienced and willing to take the risks.

DO NOT become a test pilot for new or inexperienced tow systems/operators unless you are very experienced and willing to take the risks.

Jim Rooney - 2007/07/19 14:50:52 UTC

Weak links don't always break in lockout situations... so lets make them stronger? Are you nuts?

I don't care if they're "Meant" to break in lockout. How the hell is it a bad thing if they do?

You're advocating making tow systems more dangerous for the sake of definitions. Here in reality, weak links work. They may not suit your definitions, but you're on crack if you think they're not doing people good.

And yes, get behind me with a "strong link" and I will not tow you.

I would much rather be off tow when I want to be on than on tow when I want/need to be off.

Tad Eareckson - 2007/07/20 12:42:10 UTC

OK - inhaaaaale.....exhaaaaale.....

Now back to incessant babbling...
---
Towing Aloft

Page 59

A weak link is required that will not break needlessly in response to moderate thermals, or pilot inputs, yet, will break at a low enough point to avoid disaster or excessive pilot panic.

For aerotowing operations, a weak link breaking strength equal to 80 to 100% of the total flying weight--the weight of the pilot and glider--is a reasonable starting point.

Page 60

For surface towing, there is debate on the recommended breaking strength for weak links. Since almost all modern surface based towing (static line, payout winch, and stationary winch) are tension controlled systems, the weak link selection is partially dependent upon the towline tensions used. A weak link that breaks between 100 to 120% of the total flying system weight is generally recommended.

(Oops, I had previously erroneously referenced that first page as 53.)
---
And again, from Modern Airmanship, referencing winch and AT respectively...

Page 793

It should break with a pull of about twice the weight of the glider.

Page 795

As in other types of launching, a weak link is required if the towline's breaking strength is more than twice the weight of the sailplane being towed.

---
Let's ignore, for the moment, that the former reference is talking about weak links about half as strong as the latter and focus on its recommendation of tweaking the strength to the mode of towing versus Modern Airmanship/FAA's two Gs no matter what the hell flavor of getting up you're using.

Anybody else bothered by this discrepancy?

Well, I can keep hoping.

The logic is...

In surface towing, whereas the object is to get the glider up in the air, the tow line is angled down away from it, i.e., pulling in a direction way less than optimal; therefore you're getting way less bang for your tension buck; therefore you need more tension to make up for the vector that's trying to pull you back into the ground.

In aerotowing the towline is horizontal and the tension is doing a much more efficient job of opposing drag, thus allowing you to maintain airspeed and a high pitch attitude until you reach a point at which you have a shot at continuing to go up on your own.

So, obviously, you want to use weak links proportional to the steady state tow tension of your system du jour.

Ya'd think, wouldn't ya?

WRONG.

One of several major problems with this is that around the time your weak link starts becoming useful (which it shouldn't - 'cause you should have released long before you reach that point), you're probably doing a really spectacular wingover and you don't know where the hell the winch, truck, boat, tug is gonna be relative your Center of the Universe.

Well, you can't be below boat level and still breathing and the only way you can be below winch or truck level is if there's a ravine involved but you can be in deep shit in just about any other position, attitude, or combination thereof you want to imagine. You can be straight behind a truck or straight above or below a tug, and way off to the side of any source of tension you can name.

Two... In static and stationary winch towing in the early (read critical) part of the tow, the physics and geometry are EXACTLY the same as in aerotowing. You start out with your tension source on the horizon, it stays there for a bit, then you climb a little above it. Only then do the systems start diverging. Platform launching is no guarantee against that sequence of events either. If you get a major lull in the headwind right after you hear the horn you can read the license plate real easy (btdt).

Three (again)... The sole purpose of the weak link is to break before the plane does. The plane doesn't care what the thing on the other end of the string is - Yarnell winch, Boston Whaler, Appaloosa, Toyota Tacoma, lamp post, Dragonfly - or what you were doing three seconds ago. The plane only cares about G loading.

A little more discussion with respect to Page 59...

The AT weak links recommended in the second paragraph which, on a good day and a lighter glider, fall (in theory) within the 0.8 to 1.0 G range DO break needlessly in response to moderate thermals or pilot inputs.

Addressing the two previous posts...

- If it's older it's better and safer. No reason to even look at anything else.

Nothing new there, reassuring to see the cross platform consistency.

(Kinda curious as to the point of Paragraph 5.)

I keep hearing this bullshit glider jock mantra about new equipment and test pilots and the thought finally occurs to me... What's the fucking evidence? Somebody cite an incident of someone being unable to release as a result of the use of a piece of new tow equipment because of a defect that wasn't blindingly obvious to a really slow fifth grader on the ground beforehand. And if anyone comes up with something - fear not, I can cite a whole septic tank's worth of incidents, destruction, and death resulting from the "tried and true" junk.

And...

- A single loop of 130 Greenspot is God's perfect, immutable gift to all solo gliders from 165 pound trainers to 350 pound bladewings - 1.5 Gs for the smallest stuff, 0.7 for the top end.

- And screw your equations and the USHGA AT Guidelines.

Admirable consistency there, too. But I remain uninformed of a single aerotow that was adversely affected by an overstrength weak link. (And still no trace of the old outrage concerning premature releases. Go figure.)

Wait a minute. I get it. Making them stronger makes them more dangerous so what we really should be doing is making them weaker so they'll be safer. Yep. Nuthin' safer than a tea bag string.

So, Jim, just what is your definition of a "strong link"? Lemme guess.

Based on your previous posts it trumps USHGA and has no relation to the weight of the glider.

I got it! Anything over a loop of Miracle String! Right?

A bit more on Marc's post.

- There's no reason that a multi-string release has to or should directly engage the weak link and subject the system to a hang-up problem.

- If you engage the multi-string through the thimble of one of my Shear Links instead of a loop of Miracle String you don't have the problem.

- If you use the barrel release configuration I suggested you don't have the problem.

I don't see what you can do with a bridle assembly to make it suitable or un for reverse inflation. Seems to me you'd want to be executing that operation with zero or minimal tow line tension. Pretty sure I can predict that with as much as a pound of it you won't be going up anytime soon if you're using a bridle with an auto-release mechanism.

inhaaaaale.....exhaaaaale.....

OK, I'm ready again.

Jim Rooney - 2007/07/20 21:11:32 UTC

You still fail to answer the base question... Exactly how does towing with a _stronger_ weaklink serve to make things safer?

I'll give you a hint... it DOESN'T... it makes things less safe.

The sole purpose of the weak link is to break before the plane does.

No. That's ONE purpose of a weak link. Even if that's its only intended purpose, it has other benefits. Where as using a stronger one only serves to make the system less safe.
This is what I mean by your slavish devotion to definitions.

Again... exactly how does using a stronger weaklink make things safer?

Tad Eareckson - 2007/07/21 11:21:06 UTC

Alright, I'm doing reruns now but what the hell.

I'm not primarily concerned, with respect to weak links, with making things safer - in the broken collar bones and death context of the word. I'm more concerned with making tows reliable.

You are going to have more accidents with understrength weak links. The worst I see are downtube breakers.

But from Kevin Carter a couple of years ago...

http://www.chgpa.org/forums/viewtopic.php?f=2&t=1079
$15 pacifiers

Kevin Carter - 2005/09/24 21:49:39 UTC

One pilot in the Texas Open had three premature releases in a row with glider damage on all three and different degrees of pilot injury. I myself have had a low level release that caused minor injury.

and a short dissertation about the thrills of landing in wake turbulence.

So yeah, I must agree with him that the consequences of an early pop can screw up your day more than the replacement of a seventy-five dollar faired downtube - which would be plenty enough, in my estimation.

And I will also have to disagree with your assertion that stronger weak links are inherently more dangerous.

I will, however, agree with you that one can benefit from the failure of a low strength weak link. I know of at least one example of a lucky break - so to speak.

But I don't want to make things more dangerous for everyone doing his job on the end of the string so that an individual or two can fly in an incompetent manner and MAYBE get lucky. That individual or two need(s) to continue training in controlled conditions.

About the only freakin' way I can imagine one would really need a weak link is if something catastrophic happens with a winch - like a line getting buried on a spool. In the AT environment I cannot come up with a scenario in which a weak link could possibly kick in in anything approaching the speed with which a release can be actuated.

Excellent options exist for virtually instantaneous actuation. If one is comfortable with a less than optimal configuration one can probably get to a brake lever on a downtube or a barrel in front of one's shoulder with a negligible time penalty but I don't want to dumb down the weak links to increase the chance that some bozo who has opted for that safety compromise can fumble around a couple of extra critical seconds and MAYBE get lucky.

Another bad reason for dumbing down weak links is to allow folk to fly with a release that may not work. There has been no shortage of examples of Plan B execution related to the ubiquitous spinnaker shackle based assemblies.

OK - Now do me a favor and tell me stronger than What? And there has to be a for whom in that answer.

I'm only recommending that we use weak links rated to 1.4 Gs - dead center in the middle of the USHGA safety range - or, anyway, what would have been dead center in the middle of the USHGA safety range if they had their shit together enough to define a bottom end higher than zero.

Since they don't, let's go to Plan B - Towing Aloft. As I just wrote, I don't buy that you tweak weak link strength for the type of towing you're doing, but the minimum figure cited in that text is 0.8 Gs (for aerotowing). I'll buy that 'cause it's consistent with what the FAA REQUIRES as a minimum for sailplanes.

Victor and I each weigh about 310 pounds. A loop of Greenspot falls, at best, a wee bit short of 0.8 Gs. Most of the time we can get to altitude with that if we don't get beat up too bad.

BUT -

Both of us have been doing everything right in smooth air in the ballpark of a hundred feet and - POP - back in line (or, in the former's case, - POP - replace downtube - back in line).

So as far as I'm concerned, the Golden (Green) Standard is reliable to 0.4 Gs.

That leaves any glider over around 153 pounds short of the mark.

Brian Vant-Hull - 2007/07/21 13:00:33 UTC

The outright honesty in the second line and the lack of inflammables makes this the best post yet. Let's forget everything that went before and use this as a new starting point.

I don't think there's any argument that weak length strength should scale with total mass (and I'd like to see your contraption for scalable strength weak link), and again you are honest in not having a strong theoretical argument for what the number of g's should be.

I'll be lazy and ask if any of your references give a physical reason for the 0.8 to 2 g range they quote as safe. If not, constructing a reasonable physical argument could be a major contribution. You clearly have the physics down well enough (as good as anyone else in the world) to do so.

I rarely break weak links - probably because I'm light, but I don't feel my safety has been threatened by having a proportionally stronger link than a bigger guy (purely intuitive). Is anyone else worried about my proportionally stronger weak link? Scale everyone's up to match my g ratio and I think we all could be happy?

Note that since I wouldn't have to change anything, I'm automatically happy.

Back to work .... 9 am on a saturday morning and I have to say that: tells you what I'm escaping from responding to this.

Brian Vant-Hull - 2007/07/21 23:02:34 UTC

BTW - not breaking the glider I would call an upper limit. I'm wondering if there's a lower limit that one could argue would actually increase safety by preventing weird geometries akin to lockouts, though you've argued lockouts don't require much force. Pulling up on the tug's tail?

Tad Eareckson - 2007/07/22 12:38:12 UTC

Brian,

Thanks very much for weighing in again.

Hate to take issue with anything in your post but...

Paragraph 2 of my previous is my third statement of that point in this thread. Probably shoulda made that distinction prominently up front. Sunny perked up quite a bit in a discussion of this issue we had a couple of months ago as soon as he realized that I wasn't talking about saving lives.

I think the honor of the best post yet goes to Danny for the Subject line of his 2007/05/16 submission -

"Weak links are not a secondary release system..."

If folk could just really understand those eight words.

With respect to the "lack of inflammables" that was easy this time. Jim's post was a breath of fresh air compared to the mountain of cra- oops, I'm trying to be nice for a little while - stuff with which I've been having to deal.

Let's break it down a bit...

He asked me a question, disagreed with me, quoted me accurately, made one statement with which I totally agree and another erroneous one which was easily shot down, and paid me a great - though unintended - compliment.

It took me an unholy amount of time, research, and thinking to attain that "slavish devotion to definitions" and decontaminate myself from the indoctrination of decades worth of hang glider culture.

The light bulb didn't fully glow until I was in the midst of gear fabrication some months ago and I finally got to the point of:

"Why the hell am I dumbing this thing down to do a job it's not supposed to be doing? That's what the release is for."

You use the release to release and you don't think about, count on, or use the weak link any more than you do your parachute.

Gonna throw Jim another bone - or part of one anyway.

Don't even have to use a hypothetical scenario - Robin is perfect.

He was alleged to have been using an overstrength weak link. Let's rewind the tape and dumb it down. He get's out of whack, hits the lever, nothing happens. But this time the thing pops and he bellies into the dust then get's back up and waits for a free cart. Perfectly plausible.

So we keep on using a mechanism which we always knew was problematic and hope the next guy gets lucky too.

Let's rewind the tape again, same dumbed down weak link. Spin the random number generator and this time he gets killed again anyway. Perfectly plausible too.

YOU DON'T DUMB DOWN THE WEAK LINK - YOU SMARTEN UP THE RELEASE. But we just keep rolling dice.

I actually do have a strong theoretical argument for what the number of g's should be. This theory goes as follows and begins now.

All brontosauruses are thin at one end, much thicker in the middle, and then thin again at the far end.

No, wait, wrong tape.

The next thing I'm going to say is my theory. Ready?

It doesn't matter. Anything to keep you on tow and blow before the glider does. Huge freakin' range.

Well, not really. One real world consideration I haven't mentioned before... You don't want to overload your release mechanisms. I'm recommending that they be able to easily handle one and a half times the maximum tension the weak link will allow so let's get back down to the 0.8 to 2.0 ballpark.

In addition to the references I've cited - FAA, USHGA, and Modern Airmanship - I've come across a passage from Davis citing Donnell Hewett as recommending 0.5, 1.0, and 2.0 Gs for new, experienced, and aerobatic pilots respectively. I'm not sure I buy that 'cause, as has been said ad nauseam, very low Gs are aerobatic enough to slam you into the ground and kill you.

Gotta confess though, that when I sent up Hugh on his U2 with my assembly for his first one point tow I caved to moral cowardice and incorporated a conventional weak link. He had had a history of oscillating, this was a new trick, and I wouldn't have minded seeing the line go slack early. He did fine though, and I beefed him up for the next one.

The USHGA and FAA references only state the limit(s), I already quoted everything Modern Airmanship had on the subject - which was both hardly anything and all encompassing, and Towing Aloft views weak links as a secondary release system - the concept through whose heart I'm currently trying to drive a stake.

My take on it is that - I now know what Dragonfly tow tension is and that I was able to drive through a small batch of pretty nasty shit with 1.12 Gs keeping me connected. I'm happy with a bit more than that.

If you and your Falcon weigh more than 200 pounds I wanna beef you up more than what you're happy with and reduce your break rate from rarely to never. And why should you get a free ride? I want everyone to suffer.

By contraption you mean the weak link itself? There are ten pretty good (if I do say so myself) photos up at:

http://www.flickr.com/photos/aerotowrelease/

in the Secondary Components set which illustrate the shear link variations for use on a tow line and primary bridle and as a secondary bridle. The primary bridle adaptation has subsequently been overhauled to address the wrap issue but - close enough.

Thanks immensely for the endorsement. Means quite a lot coming from an ol' physics teacher who owns meteorology textbooks containing three and a half inch long formulae.

By the way... When your doctorate paperwork comes through you can issue those degrees, right? I feel I oughta get something for reinventing sailplane technology.

Correction - Back in my initial post "1.40 plus or minus .43 Gs" shoulda read "1.40 Gs plus or minus 43 percent".

P.S.

Just caught your subsequent post.

No, I don't think there's any way a weak link can possibly keep you from getting creative. But you should have a device already that takes care of that (in addition to the basetube).

I love the idea of pulling up on the tug's tail, however. If you do that down low you will automatically be off tow without having to take any other action.

Gary Devan - 2007/07/22 16:15:57 UTC

no one really wants to admit that Homer is a caricature of us

i don't know . . . sometimes the feeling just sort of comes over ya.

Jim Rooney - 2007/07/22 16:59:30 UTC

This all follows the same mentality as "great wheel debate".
Kinda goes like this... "get rid of your wheels... land better!"

Anything to keep you on tow and blow before the glider does.

Think about this...
Basically anything less than the cabling on your glider?
You've got to be kidding me!

Sure that makes it all fit into your definition of weaklinks having a "sole purpose".

That's what I mean about reality vs definitions.
You're making things less safe because your FLAWED definitions.

Go ahead and try to improve your release... whatever. Just don't tell me that weaklinks need to be stronger! That's just flat out ignorant.

Just because you think about something a lot or talk about something a LOT doesn't make you right... you can easily chase the wrong idea around for years.

Tad Eareckson - 2007/07/22 19:32:15 UTC

Jim,

I know you don't bother reading this stuff very carefully at best and usually at all but there was additional material an extremely short distance beyond the sentence you quoted.

It began - "Well, not really.", included a recommendation that we stay within the USHGA Guidelines, and concluded with a suggestion that the middle of a rational interpretation of those guidelines is perfect for yours truly.

Also, I'll save you the trouble of referring to my post of 2007/07/04 in which I stated:

But I don't need a three G weak link 'cause if the glider has loaded up to much more than two G's the tug is probably nowhere near where I'd normally expect to find it and I'd just as soon be off tow anyway.

By the way, do you recall the author of this post from 2005/09/22:

...don't tell us that being off tow at the wrong time is all sweet and wonderful. Yes, we prepare for it, but that doesn't make it a safe situation. It makes it a manageable situation. There are times where it's better to be on tow than off tow.

Must be another loose cannon nut case, right?

I'm assuming, since you never reciprocate the courtesy of responding to questions, that you're quite happy putting all solo gliders on the same loop of Miracle String?

So do me a favor, spread some of the venom around, contact the USHGA Towing Committee and the authors of Towing Aloft, get the former and latter to lower their 2.0 G upper and 0.8 G lower limits respectively, and peace and happiness will reign with a magnitude rivaled only by the Liberation of Iraq.

Jim Rooney - 2007/07/22 20:16:36 UTC

If you wish people to read what you write, try writing LESS.
Babbling on and on about ever little detail that happens to pop into your head is not communication... it's rambling. Something you seem quite adept at.

The volume of what's written has no bearing on the validity of what's written. A fact that seems to escape you.

You state quite clearly that your idea of a "weaklink" is anything under the structural load bearing capacity of the glider or towplane.

Everything else here is based on that erroneous concept.

BTW, I know Kevie a hell of a lot better than you do dude. Please do not assume to inform me as to his towing opinions.

And as for your cracks about me being a tug pilot (and somehow less qualified to comment on hg stuff)... HAHAHA I'm a freakin hg instructor. I towed more yesterday than you've towed all year. I use this crap on a daily basis. If anyone here's less qualified to comment... It's YOU.

Tad Eareckson - 2007/07/22 20:50:24 UTC

Actually Jim, there's pretty strong evidence that lotsa people ARE reading what I write. Some of them even figured out that I wasn't talking about eliminating weak links before the two month mark.

I notice that, once again, your attention span has collapsed before the "Well, not really." mark.

I have never assumed to inform anyone of Kevie's towing opinions - I just quoted him. (I also quoted you, if you haven't figured that out yet.)

OK, you're The Master, tell us - PLEASE - at least what your UPPER limit for a weak link is (it seems clear that you don't think there should be any lower limits). Caution - it might involve an equation.

Jim Rooney - 2007/07/22 22:30:28 UTC

Hahahahahahahahaha
Oh that's just rich!
Riiiiiight... it's my attention span at issue here....
and I'm the one that's arrogant!
HAHAHAHAHAHAHAAHAHA

No, I'm not being nice. No, I do not feel the need to be nice. You're trying to convince people to be less safe. I don't want to be on the other end of the rope when someone listening to this drivel smashes in.

I've heard it a million times before from comp pilots insisting on towing with even doubled up weaklinks (some want no weaklink). I tell them the same thing I'm telling you... suck it up. You're not the only one on the line. I didn't ask to be a test pilot. I can live with your inconvenience.

Please tell me again what's wrong with the wheel? Why you keep trying to reinvent it?

Yes, please fall back on the "I'm just saying they could be stronger" bull when you've made it quite clear that anything lower than cable (1200lb) is acceptable.

The simple fact is that you're not improving the system.
You're trying to make it more convenient and trying to convince yourself that you should be towing with a stronger weaklink.

Enjoy your delusion.

Tad Eareckson - 2007/07/22 23:56:49 UTC

Thanks Jim, that'll be all I need. (Serendipity Heaven!)

Lessee, a million times from comp pilots.

Probably none of them would nag more than a couple three times but let's make it ten to be real conservative.

That's a hundred thousand comp pilots that aren't happy flying with the pussy-ass weak links such as Lauren described.

Aw, I'm feeling nice (especially now), let's divide by a thousand and make it a hundred comp pilots.

A doubled up weak link at the end of a one point bridle translates to a tow line tension of about 400 pounds.

That puts everyone from 200 (Karen) to 500 pounds within USHGA Guidelines. The top end comp gliders only go up to about 350 pounds. So we're talking a range of 1.14 to 2.00 Gs.

So Karen, towing one point, goes up to the flight line and asks for a 2 G weak link and Jim tells her she's gonna be using a single loop of Greenspot which brings her down to 1.4.

I, 310 pounds and two point, make the same request which would buy me 1.12 Gs - below what Karen has now - and get told "Take all your equations and stuff them. Here's your single." So I saddle up with something that puts me at 0.79 Gs if I'm lucky and 0.4 if I'm not.

Karen drives up during prime time, I go right behind her but - POP! - SHIT!, and Karen kicks my ass on the scorecard.

KAREN! You freakin' WEASEL! I am REALLY REALLY disappointed in you for capitalizing on that sleazy tactic.

So there's a hundred USHGA AT qualified comp pilots who've wanted to tow mostly towards the middle of the USHGA safe range and they've all been told to get bent. Anybody have an idea of a list? I'd like to get together with some of these folk for a few beers and a little glider talk.

Jim Rooney - 2007/07/23 00:06:46 UTC

I'm glad you're finally starting to understand.
See you've been advocating STRONGER weaklinks than even USHGA guidelines.
I've been advocating WEAKER ones, as you've noticed here.

In fact, you're not just advocating stronger ones... you're advocating MUCH stronger ones.

Yes, this is my problem with all this.
Thanks for noticing.

Marc Fink - 2007/07/23 01:17:22 UTC

Tad, why not just shoot yourself out of a cannon?

Matthew Graham - 2007/07/23 02:14:04 UTC

Karen

Tad,
Where did you get this idea that Karen hooks in at 200? Are you blind?
She's 5'2" and weighs 115 and hooks in at 25 lbs more with harness, chute, etc.
Egads! Popping wink links isn't your only problem.

Brian Vant-Hull - 2007/07/23 02:46:24 UTC

Add her glider. Tad's g ratings are for the whole package.

Actually, unbelievable as it seems, I don't think Tad and Jim are that far apart. Tad wants to use the current number of link-g's the lightest pilots use, and scale accordingly for all the rest. Jim would prefer to use the current number of link-g's the heaviest pilots use, and I infer would like to scale accordingly down to the lightest pilots.

People go ballistic when Tad says weak links are just to protect the structure, but he then is willing to weaken it enough so that lighter pilots are within his range when using current weak links.

All the argument seems to be about which end of the scale to use that is currently in use. I really can't see what all the hyperventilation is about.

Marc Fink - 2007/07/23 11:14:35 UTC

...All the argument seems to be about which end of the scale to use that is currently in use. I really can't see what all the hyperventilation is about.

Exactly. Tad says we go to the upper end, we say it's fine where it is. Tad says "inadvertent" breaks are malfunctions which will kill you and inconvenience him with waiting an extra 3 minutes on the flight line while he's eager to go after that huge xc flight or Manfred's world distance record; we say it's the weak link doing what it's supposed to do. (it's a wonder he tolerates tandems on the same day he's out).

Why are we "hyperventilating?"

Because Tad has:

1. Continued to attack us and call us names just because we don't agree with everything he says.

2. He has also insulted the integrity of several professional instructors and implied that they are deliberately putting students at risks.

3. He has donned the hat of part-time NTSB crash investigator and used anectodal accounts of spectacular accidents to bolster his arguments.

Most of all, Tad shows up and mostly just hangs out--I never hear of him flying much, and he uses outdated equipment which in itself may be contributing to HIS problems with towing. I was there at the Tow farm and when Highland first opened--if Tad ever showed up I don't remember it--but it was very infrequently.

Ironically, I've always admired Tad's creative way at looking at things, and I have seen the equipment he's made with his own hands--it is beautifully made stuff. Why can't he just quietly introduce the stuff to pilot friends and leave us to make our own minds up--rather than using weird science and hate tactics to scare us into submission? Even if Tad were right--using negativity is a poor marketing tool.

You keep bugging that dog and eventually it's going to get mad and bite you.

Brian Vant-Hull - 2007/07/23 13:31:43 UTC

I'm not defending the name calling and insults, just trying to point out that what he's saying is not as wacky or thoughtless as his often unfortunate way of selling it. I guess if I was one of the multitudes that's been insulted I wouldn't be interested in seeing it.

Isn't scaling the weak length strength to match the total mass a good idea?

If so, you can complain that with the current one-size-fits-all links either
a) light pilots have overly strong links and are a safety risk
or
b) heavy pilots have overly weak links and/or are a safety/convenience problem.

Since with the current one loop weak link system I've never heard anyone complain that light pilots have a safety issue, I asssume that this g-ratio is considered safe and we can scale up from there, thus reducing inconvenient breaks. This may be counterbalanced by the inconvenience of constructing the scalable weak links.

Marc's advice about a change in marketing style sounds good, Tad. The word is out, let it soak in on its own.

Jim Rooney - 2007/07/23 14:11:06 UTC

Oh that's not what this thread's about... that's just where it's degraded to.

Tad started spouting off about putting weaklinks on the tow line, not the tow bridal.
zzzz (it's being done out there ya know and us simpletons actually considered all this stuff long before you thought of it)

As is always the case (because Tad has NO TACT), it quickly degraded into Tad blathering on and on and on and on and on.

I especially love the dire warnings of "don't trust your weaklink!"
Remember, look both ways before crossing the street!

I love hearing the towing 101 crap from someone who barely flies.
Thanks, I really didn't know all that.
I feel much safer now.

Steve Kinsley - 2007/07/23 14:31:10 UTC

Seems to me that Tad has devised a system for making weak links of whatever strength we want. This is good. This could be a real advantage for light pilots who feel that the weak link is a safety issue and that they are effectively flying without one. These folks could get a Tad Industries "Minus 20". (that is greenspot minus 20lbs) The heavier folks or those who fly high performance gliders with a lot of energy retention could get a "Plus 40".

I am flying with a Tad Industries plus something. Plus a lot I suspect. It probably would not break if I came off the cart crooked and initiated a wing over. The only reason I am doing this is that I also fly with a mouth release which I feel pretty much makes the low level lockout protection function of the weak link (if indeed it performs this function) superfluous.

I think towing is really safe compared to mountain flying and that we are wrestling over minor improvements and what constitutes an improvement. I think the ability to vary our weak link strength counts as a real improvement. Now we just have to get Tad Industries to make what we need not what he thinks we need.

Jim Rowan - 2007/07/23 15:37:58 UTC

I don't pay much attention to the Tad freak-show, but I do disagree with Steve's comment about towing being really safe compared to mountain flying. The mere fact that there are so many more variables and mechanics involved in towing a hang glider than in launching off a mountain make towing a more complicated, and potentially, more dangerous process. There are no other humans involved when you launch of a mountain. So when you add the human-factor, the possibilities of mechanical failure, and the other variables involved, I believe towing is more dangerous. Having said that, I do both and consider the risks of both types of flying acceptable in comparison to the rewards involved.

Marc Fink - 2007/07/23 16:04:01 UTC

JR dude--I used to think the same way--but after 11 years of aerotowing I really wonder if the frequency of launching aerotow versus Ft launching really supports that arguement that one method is inherently more dangerous than the other. I strongly suspect not--but I can't prove it.

marc

PS: You're wrong about a short-pack revision to the Sport 2 coming out any time soon. See all the trouble you caused on the OzReport!

Jim Rowan - 2007/07/23 16:58:23 UTC

I didn't say they were making a short-pack version of the Sport 2. I simply reported a conversation I had with Steve Pearson at the 2006 WW Wallaby party in which he told me that was his next project. Maybe it got moved to back-burner or wasn't feasible, but he really did tell me that.

I have aero-towed, off and on, since the late 80's. First with Bill Bennett and John Pattison behind a trike that flew way too fast and then later at the Wallaby/Quest flight parks (and now Highland, too). I still believe that the added complexity, mechanical and human variables tend to permit more things to go wrong and, therefore, towing is somewhat more dangerous than foot-launching, but I have no statistics to prove that and consider them both acceptable risks. I used to have this discussion/debate with Bill Bennett all the time. Then he went and got himself killed to prove my point.

Hugh McElrath - 2007/07/23 17:04:35 UTC

Seems like there *are* more variables in the mountains: wind direction is more critical, obstacles at launch. Seems like we also fly in stronger conditions in the mountains - it makes the mountains work better, the gaps are easier to jump, sometimes you can get wave. But as some have pointed out, this benefit comes with risk. Strong wind shreds the thermals in the flats, so there's less incentive to fly then/there. So, if we have more incidents/accidents in the mountains (just my impression - anybody know for sure?), it may be because of the conditions we choose to accept.
My 20 cents worth (everything is getting more expensive these days).

Marc Fink - 2007/07/23 22:27:58 UTC

Jeez--I wonder if Bill knew his accident would be supporting so many points of view he'd be rolling over in his grave. But I'm going to leave that one lie, thank you.

I agree that towing in general is more complex and thus requires "more checks and balances" to ensure safety margins are maintained. But the added elements of complexity and human interaction do not in and of themselves make the method more dangerous--by that line of reasoning flying commercial airlines would be a preposterously risky activity. And the probability of launching unhooked is certainly far less when aerotowing.

As for Steve at WW--you know he is always working on improving everything in Wills Wing's line up. As soon as someone "lets the cat out of the bag" the rumors fly and you get stuff like that guy who thought his sport 2 would be worthless and felt he was being ripped off. What the heck--I guess the still benefit from the publicity anyway.

Bacil Dickert - 2007/07/23 22:56:56 UTC

commercial airlines

Marc,
At one time flying commercial airlines was a helluva lot more dangerous than it is today. Of course you can do the statistics, so statistically you may be more likely to die from a lightning strike or a car crash than a commercial airline crash. So by that logic, flying a commercial airliner is "safer" than driving. But here is another way of looking at it: when sh*t hits the fan with a commercial airliner, like Sao Paulo, survival is highly unlikely versus a car crash or getting killed by lightning.
Applying that logic to towing versus mountain flying, let's say sh*t hits the fan right on launch (which is where sh*t does hit the fan!!) with the two methods of getting airborne. Lockout at low altitude cratering in versus (around here) getting treed or otherwise. Which is safer? Don't really know. The statistics (I don't have them) would show one way statistically is safer than the other. But what has to happen in both methods to get out of the bad scenario? Towing depends on a few more things than just maybe a simple weight shift and pull-in (the simplest correction in mountain flying). A release has to work if things get past the point of no return (if the pilot's release doesn't work the tug pilot's release better work) and there has to be sufficient altitude to recover from a bank angle that is undesirable. And the ground generally does not fall away from you at a towing location like it does on a mountain slope (quickly giving you vertical distance between yourself and solid objects).
I am not saying one method is better to get airborne than the other. It's just another choice facing the local pilot.

Tad Eareckson - 2007/07/23 23:46:43 UTC

What Tad has consistently has recommended has been that EVERY qualified AT pilot tow, not at one end or the other, but DEAD CENTER IN THE MIDDLE OF THE 0.8 TO 2.0 SAFE RANGE - 1.4 Gs. The highest number anyone will be able to quote is 1.44 which, in the example cited, allowed a negligible amount of slop dictated by steps of available graduation.

(Tad responded to a question Brian posed on theory but immediately qualified his answer. That obviously was not a recommendation but has been disingenuously portrayed as such in a tactic similar to the one which resulted in a headline reading "How can 57 million Americans be so stupid?")

The only other deviation from that high water mark has been towards or possibly beyond the low end of that range, as recommended by Donnell Hewett for a pilot new to towing or (as in Hugh's case) a mode thereof.

Jim has left the impression that if a 350 pound comp glider with a two point bridle shows up he will refuse to tow him with anything heftier than a 0.7 G weak link but is perfectly OK hauling a skinny Hang II kid on a little Falcon at 1.5 Gs.

Tad has specifically and repeatedly said that unnecessary weak link breaks will NOT kill you. They can, have, and will result in broken downtubes, minor injuries, ruined flying days, lines lengthened enough to lock people out of windows, lowered competition scores, pissed off pilots, wasted fuel, and higher towing costs.

Tad has not attacked, just counterattacked. Find some of Tad's nastiness and check what preceded it. Check Jim's first couple of posts for examples of tact and interest in establishing and maintaining an academic discussion. I did have a conversation at Ridgely with a reader who had been stunned by the rudeness with which I was treated as this thread started rolling.

Tad has not called anyone names. The only name calling I recall in this thread was something about a "missing link".

Yep. When a glider goes down on tow Tad does the NTSB thing and sucks up every shred of information he can get his hands on and occasionally winds up with some insights that a lot of other people don't have. Tad also welcomes any discussion or debate on the issues of a higher caliber than the Tad's-full-of-shit sort of thing.

Tad has an old glider in nice condition that thermals with the best of them and gets killed at bar pulling time. But Tad has it fitted with tow systems which are eons ahead of anything out there. They are efficient light, strong, clean, and oozing with redundancy and can be actuated with little more than a thought. Tad doesn't have any problems with his towing - Bill, Mike, Mike, Robin, Holly, Arlan, Jeremiah, and anyone who has ever reached for a secondary or popped a weak link do.

Tad was a Basic Instructor back, what, before Jim was born? Tad has about three and two thirds hundred hours of airtime, a handful of dune flights in excess of an hour (or two), and was a Smithsburg site record holder (before Marc cracked it). Tad was at Ridgely its first day of operation and was looking down at the runway from over eight grand two days later, has made it out 37 miles, has punched the clouds a few times, and has stayed up long enough to start falling asleep. (Tad was also at the tow farm long enough to see a Dragonfly flip on its back (and thus prop) in an incident precipitated by a chintzy secondary bridle disintegrating.)

And none of that has the slightest bearing on this issue 'cause this has nothing to do with flying skill and everything to do with physics.

Donnell Hewett was not a tow pilot. He was/is a physicist. He had enough brains to look at the tow systems and figure out how to do them right. He got attacked and censored. It's a pretty good bet that people died who didn't have to. Les King - of the USHGA BOD at the time - was big enough to say (to me at Sport Flight) "We were wrong."

None of what the aforementioned or I have done requires ANY ability to fly a glider or anything else. And no amount of flying experience automatically qualifies anyone to evaluate these systems.

Marc, when you say "we say it's fine where it is." - is that the Royal We? 'Cause Jim just cited something between a hundred and a million comp pilots who definitely don't say it's fine where it is - and have been denied the right to do anything about it.

This is not "weird" science - this is simple and solid. Only one calculation requires a bit of trig and for that you can substitute:

tow line tension equals twice bridle tension over 1.15

Now it's all grade school arithmetic.

I really appreciate your comments on my systems and there do happen to be a few people using them. But at the rate folk are catching on I'm gonna have been dead a long time before anything significant snowballs. So I'm not gonna shut up and go away as long as people are reading, questioning, and challenging.

I also appreciate it when you raise a legitimate concern or disagreement. But if I come back with the logic, numbers, data and/or question I'd like to hear it acknowledged, answered, countered. And when a statement is attributed to me I wanna see quotation marks - encompassing all relevant content.

This hasn't been a lot of fun and it needs to be a two (or twelve, whatever) way street.

With respect to weak link implementation...

- If you put the weak link between the tow line and a two point bridle you only need a few of them to run the operation and the bridle can't wrap after a weak link break.

- It's not worth it to use this concept on a bridle which is engaged by a spinnaker shackle 'cause it'll get chewed up.

- If you tow one point you can use the shear link cheap and easy and keep it with you.

These weak links maintain a reliable rating indefinitely and do not wear with use - 'cept for maybe the ones on the back end of the tow line as a result of dragging.

Yeah, I can get a bottom end Falcon down to 0.78 Gs. With a loop of Greenspot on the end of a two point bridle you're looking at 1.50.

But, like Brian said, we don't seem to be killing a lot of Karen/Ayeshas with the 1.4 target I'm shooting for so - why bother?

Yeah Brian, fabrication of the version of this thing that goes on the towline is labor intensive. But you only have to do it once. Cutting a length of Greenspot and tying it in a loop is a relative non issue. But you gotta do zillions of them. And when a tug has to do a go-around, a glider has to be recovered (and, occasionally, repaired) and restaged, and there are a bunch of people who've already killed a third of the day making it to the line baking in their harnesses, the construction inconvenience / expense ratio consideration fades pretty fast.

Yeah, my fuse has been a bit short through a good chunk of this but I've had a lot of things coming at me from a lot of different directions. (I've also had a backlog of a few items not on this thread.) And you've been too tied up lately to do moderator duty.

Yeah Steve, I'm pushing hard for what I think you need, but I can be worn down. Case study - PK...

I tried to wear him down and got close once or twice. He managed to temporarily get rid of me by saying that he's light and isn't breaking stuff very often. I think he's 250 and the Greenspot on his one point gives him 1.12.

I can compromise and put him more reliably at that rating with the next to lowest link of that flavor.

I'd just as soon not go too far down from 1.4 'cause I have the plus/minus twenty percent tolerance thing to worry about.

(Steve, what did I give you? Black/Orange? And what do you weigh? Gimme that and I can tell you tow line tension and Gs. I guess you must have gotten port and starboard equalized since we last crossed paths?)

Tad Eareckson - 2007/07/24 10:58:04 UTC

More on the Royal We thing.

Marc Fink - 2007/07/23 11:14:35 UTC

Tad says we go to the upper end, we say it's fine where it is.

Again, Tad says go to the middle, but...

It's fine where it is FOR WHOM? Karen, me?

Let's say that using a 1.40 G weak link is as insanely dangerous as Jim contends and 0.79 is perfect.

SO YOU'RE GONNA KILL KAREN AND LEAVE ME UNSCATHED?! Let's take a poll - nah, don't bother. Reality check time.

Jim also makes the point that the glider driver isn't the only one on the line and he didn't ask to be a "TEST PILOT" and subject himself to gawd knows what unpredictable horrors might await him as a result of a double loop of Greenspot on a bridle. But, hey, as long as there are two people dangling behind that configuration, no problem, do it thirty times a day, hardly notice when the thing pops...

Right?

That's some of what's wrong with the wheel.

When I first kissed the Greenspot bye-bye, I figured I'd just carefully duplicate its strength with the more reliable version. Can't get in trouble that way, right? It would have put me at around the bottom of the range and I cheated an extra stitch or two.

As I started figuring that, as Steve just expressed, that there was no way I would be counting on the weak link as an emergency release (which no one can afford to do anyway), goal number two was to take the strength up as high as I could and still leave the weak link near the front end of the tow line intact. So I flew at 1.12 Gs for a while.

Stage three, I said "Screw this, I want a 1.4 G weak link and what's up front is not my problem. I'm just responsible for this aircraft."

So as things stand, if I exceed about 1.29 Gs I'm gonna end up with 250 feet of Spectra. OK, happens with the tandems every now and then, I'll deal with it. But I don't expect that to happen 'cause I've gotten off tow at under 0.8 Gs in a lockout before and I'm real confident that I can do it again.

I'd like to see the strength up front go up closer to what folk thought it was to begin with but that hasn't happened yet.

The tug driver doesn't really have to worry about what's on the glider 'cause he has his aircraft protected with whatever he wants and, if he doesn't like the reflection in the mirror, he also has a lever to take care of that problem.

Marc, from you...

Marc Fink - 2007/05/21 17:05:41 UTC

Ain't no device going to mitigate the fact towing in turbulence is riskier and takes more piloting skill. Changing your breaking pressures is only going to shift the bar on the decision set that the pilot must make in those split seconds during initial tow. Tad is correct in one statement--the weaklink does protect the plane, especially during roll-out and liftoff. Upping the load limit means more trust will be placed in the towed pilot in doing the right thing. keeping the line under higher pressure at initial lift-off, IMO, will increase the probability of lock-outs over the broad range of pilots and conditions, while increasing the risk to the tug as well.

Yeah, getting slammed in in those first split seconds is the nightmare scenario. I've thought and worried about it for years.

OK, if there's no turbulence it's not worth going up, so we're going to be towing in turbulence.

I don't think anything catastrophic has ever happened in the first split seconds - 'cept maybe having your bridle routed under the cart tubing (a finger on the trigger is about the only thing that might help you with that problem). The bad stuff happens in the course of seconds.

And, I said this at the time but again... The probability of a lockout cannot be increased by beefing up the weak link - only the extent.

The tug is always protected by its weak link, independent of your selection.

And both pilots have the ability to actuate the release long before the weak link can kick in - once somebody makes a decision.

Yeah, the towed pilot has to do the right thing - just like an untowed pilot often has to make instantaneous reflexive corrections clearing the slot or putting it down in the primary at Woodstock.

Marc Fink - 2007/07/24 11:20:37 UTC

Re: commercial airlines

Interesting argument--but sorry, I think your points are, like mine, subjective at best.

I've heard speculation about this low-level lockout stuff while aerotowing and not being able to release--I think this event is incredibly rare and suspect that pilots get gusts and PIOs mixed up as lockouts--but whatever.

I could easily argue that aerotowing is a FAR more reliable way to set proper AOA and necessary airspeed than footlaunching. The fact that your launch area and LZ are one and the same (and generally flat and very large) I could also argue is FAR safer than crashing through the trees into a steep mountain slope in case the glider takes off and gusted putting it into a roll and turn into the mountain. I've seen this happen to MANY pilots--including the best--and it has KILLED and injured many pilots over the history of our sport. I have NEVER seen a lockout aerotowing while lifting off in the first 100 ft or so.

I agree with Jim's basic premise that there are inherently more items to check when aerotowing--so at some level there is a greater risk of human error being introduced into the system if all people involved are not absolutely careful and professional about what they do. And I have seen aerotow operations--big ones even--that can be lax about maintaining that degree of care. But if those systems are being operated carefully and professionally--then the actual method of aerotowing as a means of getting a glider into the air I do not believe is any less safe than footlaunching. And many pilots might, like Steve, feel its actually safer. In truth, the biggest factor influencing the safety of a launch--whether it be aerotowing or footlaunching--I believe is THE PILOT.

Lets talk about something else not based on opinions--like wheels, full-face helmets, or even weaklinks, eh?

Jim Rooney - 2007/07/24 13:07:31 UTC

We've descended into FL vs AT and Tad is no referring to himself in the 3rd person?! Hahahahaha
Wow, this is really turning into a freakshow.
Ok, it's always been a freakshow, but it's taken on a whole new level.

I'm with Marc... hrm... lets see what else....
Wheels vs no Wheels
FLPHG vs FL
Insurance
USHGA vs USHPA
Fullface vs Saladbowl
Double hangstrap vs Single
Zero pressure releases
Marketing
Accident statistics
Rigid vs Flexie
Drogue Chutes!

Be creative.
There's so much to piss and moan about! Why get bogged down on just one?

HAHAHAHAHAHAHAAHAHAHAHA

Marc Fink - 2007/07/24 16:30:36 UTC

You forgot paragliders--the biggest crisis facing the world next to global warming.

Gary Devan - 2007/07/24 18:26:22 UTC

Tad Eareckson - 2007/07/24 10:58:04 UTC

More on the Royal We thing...

---
so, i pretended that i was an editor and rewrote some things, believing that i did not *materially change* anything and expanded some things to include that which *i* thought was self evident, implied, and that you would agree with.

however, that then left this statement/conclusion inexplicable.

"That's some of what's wrong with the wheel."
---
"i, tad, say we go to the upper end ,others say it's fine where it is."

Again, Tad says go to the middle, but...It's fine where it is for whom?

Let's say that using a 1.40 G weak link is as problematic as some contend and 0.79 is a good, working compromise.

i contend that that compromise puts lighter weight pilots at greater risk, a risk that i believe to be unnacceptable and unneccessary.

a tug pilot arguably(?) is more frequently exposed to the risks of towing - he's always the guy on the other end of the line. doing this as a business requires that other people have confidence in him. thus he's probably (justifiably?) very wary of subjecting his reputation, himself or others to ideas/techniques/equipment of which he doesn't have confidence.

*That's some of what's wrong with the wheel.*

When I first kissed the Greenspot bye-bye, I figured I'd just carefully duplicate its strength with the more reliable version. Can't get in trouble that way, right? It would have put me at around the bottom of the range and I cheated an extra stitch or two.

As I started figuring that there was no way I would be counting on the weak link as an emergency release (which no one can afford to do anyway), goal number two was to take the strength up as high as I could and still leave the weak link near the front end of the tow line intact. So I flew at 1.12 Gs for a while.

Stage three, I said " I want a 1.4 G weak link and what's up front (with the tug pilot referenced above) is not my problem. I'm just responsible for this aircraft." - not the whole business of running a tug with people on a line behind me (again, see tug pilot referenced above).

So as things stand, if I exceed about 1.29 Gs I'm gonna end up with 250 feet of Spectra. OK, happens with the tandems every now and then, I'll deal with it. But I don't expect that to happen 'cause I've gotten off tow at under 0.8 Gs in a lockout before and I'm real confident that I can do it again.

I'd like to see the strength up front go up closer to what folk thought it was to begin with but that hasn't happened yet.

The tug driver doesn't really have to "worry" about what's on the glider ("worry" is in quotes because of course he does worry, it's part of what people count on him to be doing, otherwise he'd have to be pathological (to not worry)) ''cause he has his aircraft protected with whatever he wants and, if he doesn't like the reflection in the mirror, he also has a lever to take care of that problem.
---
'did this as an exercise to explore the idea of what other people "hear" you writing is not the same as what you "hear" you writing.

not trying to be tricky here. am vowing to myself that i'll not follow up with anything, regardless.

(still gotta press the 'submit' button . . . gulp . . .

Gary Devan - 2007/07/24 18:28:36 UTC

shit! my dog lunged at the keyboard! i wasn't gonna do it! shit! come here you damn dog . . . !

Bacil Dickert - 2007/07/24 23:04:24 UTC

The chain

Marc Fink - 2007/07/24 11:20:37 UTC

In truth, the biggest factor influencing the safety of a launch--whether it be aerotowing or footlaunching--I believe is THE PILOT.

I have to disagree with you Marc. With aerotowing the pilot is one link in the chain. The chain has 5 links: (1) the tug pilot (2) the tug pilot's release (3) the weak link (4) the tow pilot's release (5) the tow pilot. If chain link #5 is having a bad day at low altitude, then chain links #4, #3, and #2 better work, in that order. There is more influencing the safety of what is going on than just the pilot. Forgot a 6th link: the tug engine, another variable affecting the safety. Mountain launching has one chain link: the pilot. It's all on the pilot to determine the safety of the launch.

Marc Fink - 2007/07/24 23:38:28 UTC

Re: The chain

Didn't I already agree that there are more factors involved in aerotowing that can potentially introduce human error? If I didn't, I'll say it again--yes. But that still doesn't prove that just because the potential is there that ON AVERAGE AEROTOWING IS MORE DANGEROUS THAN FOOTLAUNCHING. It simply means more people are involved that have to work together as a team to see to it that things go safely. I could even flip your argument and say the probability of a contentious tow operator preventing you from flying in dangerous high winds is better at a towpark than it would be, let's say (hypothetically speaking of course ), if the same pilot decided to go to a mountain launch and fly in high, gusty winds on a low performance glider where he is the only decision maker. But I think your last sentence is in agreement with what I'm trying to say.

Me personally--I don't care--my favorite method of launching is the one that gets me into the air--and it's the most dangerous. I hope I never have to blame someone else or my equipment for my lack of abilities (although that might be why I keep buying new gliders ).

Bacil Dickert - 2007/07/25 01:03:15 UTC

MTBF

Marc,
The first part of your flip will remain hypothetical because it will never happen. And I did not say that on average one method was safer than the other. All I said was that I disagree with you stating that the pilot is the main determinant of the relative safety in aerotowing. That is all. Nothing more, nothing less. Only mathematical analysis of failure rates of the mechanical links in the aerotowing chain will determine the overall MTBF rate of the aerotowing system, and where the real "weak link" really is. And the MTBF has nothing to do with human error.

The main thing that allows pilots to fly another day is to always leave yourself an out, whatever that out may be.

Marc Fink - 2007/07/25 12:36:34 UTC

Re: MTBF

I think we're playing word games here. I said the biggest factor determining safety for any launch method is the pilot--you say it isn't in the case of aerotowing. By this, I take it that the other factors in this chain of links in aerotowing, either singly or collectively, are a bigger factor in determining a pilot's safety (if you meant something else it isn't clear to me what that is). Tugs must all be FAA registered, N-numbered and annually inspected by a licensed inspector to certify their airworthiness. I don't think the same can be said of most hang glider pilot's gliders. Most reputable aerotow operations are in business because they have a vested interest in maintaining high standards of safety and easy access to launching--at every link of the chain.

We've expended a whole lot of angst over this whole towing safety thing--starting with Tad's weaklink jihad. I'd like to ask--when having problems with landings--doesn't it make sense to look at your gear, adjust it properly, then go out and practice your landings to improve? Wouldn't it make just as much sense to go out and practice releasing at various stages of a tow--including rolled hard (while high, of course) or low down just to see what it's like and get better at dealing with those potential "safety weak links?"

Jim Rooney - 2007/07/25 18:45:13 UTC

Ha
We do that with all our students.
You can't solo till you've been through the ringer.

Marc Fink - 2007/07/25 20:48:53 UTC

Re: MTBF

Bacil Dickert - 2007/07/25 01:03:15 UTC

The first part of your flip will remain hypothetical because it will never happen.

What, that tow operators will advise/prevent you from launching even if you want to? Happens all the time. If you mean flying a low performing glider in the mountains in strong conditions--that happens all the time too." (I know I've flown my Falcon in 35 mph winds up here! )

Bacil Dickert - 2007/07/25 22:00:52 UTC

Bingo!

Marc Fink - 2007/07/25 12:36:34 UTC

I said the biggest factor determining safety for any launch method is the pilot--you say it isn't in the case of aerotowing. By this, I take it that the other factors in this chain of links in aerotowing, either singly or collectively, are a bigger factor in determining a pilot's safety.

Marc,

Exactly ! That was the point I was trying to get across. As for the hypothetical situation you described in the first part of the flip, it will never happen to me specifically, but that's by choice.

And Tad is trying to improve the MTBF of the aerotowing system with his reliable releases, right Tad ? Oops .

Marc Fink - 2007/07/26 14:51:38 UTC

I've cored sink. Time to pull VG and go on glide!

Tad Eareckson - 2007/08/01 11:56:37 UTC

Sorry, took a bit of time off to work on photos of the new bridle/weak link designs. They're up at:

http://www.flickr.com/photos/aerotowrelease/

I'm calling them "Ribbon Bridles". I'd prefer not to admit how long it takes to stitch together three or four ten foot strands of low stretch line but I have a pretty good idea that it will be impossible to wrap these things.

From Marc, near the beginning of the discussion:

Marc Fink - 2007/05/18 14:16:20 UTC

You toss around load limiting figures without any real asociation to breaking strengths and desired load limitations.

Odd, coming from someone in the faction which has so steadfastly maintained precisely that approach.

Jim actually has no idea when I thought of putting the weak link on the towline instead of the bridle. I didn't think of the idea at all - I, however, had been aware of but quickly discarded the concept years before Jim ever got a carabiner anywhere near a glider. Until last year I had assumed that a weak link had to be a loop of string and didn't like the idea of dragging and degrading something that could determine the duration of my tow.

Jim doesn't define who "us simpletons" were and why they rejected the configuration. Peter Birren, the individual Marc recommended for checking my arithmetic, is a strong advocate and I'm pretty sure Donnell Hewett is so rigged when he gets behind a tug.

Somewhere there's a photo of the 2004 edition of Charlotte Baskerville taken immediately after a hop with Sunny at the wheel. Let's use Photoshop to replace the latter with Adam. So now we're getting to the neighborhood in which a tandem glider with a light pilot and seven year old passenger might weigh less than a bladewing heading for Ocean City.

So I'm wondering why it's insanely dangerous for a heavily loaded solo glider to use a double loop of Greenspot but not a lighter kitecycle built for two.

A single loop on the end of a two or one point bridle might buy you around 243 or 280 pounds of tow line tension respectively.

The following is a list of known rabid maniacs who tow with "strong links" listed in order of and along with their maximum tow line tensions in pounds (sorry guys).

323 - Tom
348 - Victor
350 - Sunny
351 - tandems
378 - Steve Padgett
400 - Christian
420 - Hugh
420 - Steve Kinsley
470 - Tad

(Note the inverse relationship between pounds and IQ.)

Tom gets an asterisk. I think he was using a loop of 150 but has run out of that flavor of string.

For all the work I've put into this stuff, a double loop of Greenspot (as I just wrote the latter Steve who recently had another single pop for no reason at half a grand) ain't a bad one-size-fits-all solution.

The respective two and one point ranges are around 174 and 200 to 435 and 500 pounds. But if you have the opportunity to hit the middle...

I think one reason that the concept of a weak link having to be something on the ragged edge of failure under normal tow loading has been able to metastasize for so long is the availability of the USHGA Aerotowing Guidelines.

Go to the national organization's web site and try to locate that information. I've been sucking up everything I can find for years and it wasn't until half past April when I registered and was cleared for membership in an obscure tugs discussion group that I was able to get my hands on a PDF file. Prior to that I figured we should be duplicating sailplane specs.

No oops, Bacil. Well, a little oops. I'm not trying to increase the MTBF - I've done it - often with, of course, the help of others whose concepts I've ripped off and expanded upon. Now I'm just making the presentation.

The F, of course, doesn't have to be a Fatality or Fracture. It can just be an "Aw, Fuck - back in line."

One easy way to increase the MTBF is to increase the airtime to launch/landing ratio. On 2007/06/07 Yuriy Koziy had to come down prematurely. The lift, not the weak link, gave out but it just as easily could have been a case of string fatigue. "Landed" - in the wrong place - two faired downtubes, a smashed Flytec case, and hurt enough to end his participation in the ECC.

Gotta disagree with you about the chain links thing - you're making it too complicated.

For the purpose of this discussion, lemme cheat a little and throw out landing in tug wake.

The stuff that you don't own can't hurt you. To reiterate the list - everything from the tow ring forward - the tug and its pilot, engine, release, weak link, tow line, and ring. If you crater in it won't be 'cause the tug fell apart, the driver decided to kick in the turbocharger, dump power, and/or fly under the power lines, the engine ran out of gas or seized, the tow line or weak link broke or didn't, or the tow line wrapped or carabiner hooked on to your wires.

It'll be 'cause you screwed the pooch.

If you screw up just off the side of a mountain - you're on your own.

If you screw up just off the cart - the tug can do things to compensate and maybe bail out your sorry ass but it's not responsible for the predicament into which you put yourself.

Bill and Mike didn't die because of "an inexperienced tug pilot who dumped power when he shouldn't have". They died because they stalled the glider.

The tug is just there so you can have fun. If the fun starts dissipating there's no reason you have to keep following it.

Jim Rooney - 2007/08/01 13:47:23 UTC

Here we go again with more of the "you're better on tow in a bad situation" BS.

Your assumptions about what we're doing on the tug end are wrong.
The #1 thing I can do for you just off the ground is GIVE YOU THE ROPE.

Whatever's going on back there, I can fix it by giving you the rope. Any work I do is to save the tow and get you back in line... not to save you. I do this only when I think it's safe to do so. When I give you the rope, I've determined that continuing the tow is putting either you or me (or both) in jeopardy and I'm trying to save you (or me).

Brian Vant-Hull - 2007/08/01 16:30:20 UTC

Once again I see no contradiction between what the two of you are saying. Tad said:

Tad Eareckson - 2007/08/01 11:56:37 UTC

If you screw up just off the cart - the tug can do things to compensate and maybe bail [you] out .... but it's not responsible for the predicament into which you put yourself.

The tug is just there so you can have fun. If the fun starts dissipating there's no reason you have to keep following it.

Translation: If something's going wrong, the HG pilot should get off tow.

Jim said:

Jim Rooney - 2007/08/01 13:47:23 UTC

Whatever's going on back there, I can fix it by giving you the rope. Any work I do is to save the tow and get you back in line... not to save you. I do this only when I think it's safe to do so. When I give you the rope, I've determined that continuing the tow is putting either you or me (or both) in jeopardy and I'm trying to save you (or me).

Translation: If something's going seriously wrong, the TUG pilot will get off tow.

Sounds like the same thing from opposite ends of the rope. Nobody's counting on the weak link anyway.

I've already restated the whole argument as whether the link should be on the high or the low end of the broad spectrum we've been happily using for years. And once again, since nobody's been worrying about lighter pilots, I think Tad is right to aim for the high end, BUT ONLY if we start scaling the weak link strength for total mass. I didn't come to this realization until fairly late in the thread, and wouldn't have if I wasn't such a lightweight.

Unless there's something particularly amusing to comment on, as far as I'm personally concerned the argument and thread is done. Somebody might flame me back into posting...that's just another form of amusement.

Gary Devan - 2007/08/01 17:09:10 UTC

form of amusement?

well, any excuse to put off doing what i've been doing.

Jim Rooney - 2007/08/01 19:49:30 UTC

Not we're not saying the same thing.

Tad's saying that I can fix things without giving you the rope.

I'm saying that I can lessen the effects of your screwups. I don't "fix" anything, I just keep you from smashing into the ground by lengthening the time between you and lockout. You have to "fix" things, I just give you a second (from my bag of safety!) for you to do it in.

It sounds similar, but there's a world of difference.
Ya'll need to think long and hard about cutting into my margin of safety... cuz that's what you're talking about.

It's more of this crappy argument that being on tow is somehow safer than being off tow.

Tad Eareckson - 2007/08/03 17:39:38 UTC

I so do love it when I see quotation marks around a statement which is pretty much the opposite of something I've written.

Thank you, Brian, for actually reading what I've said before commenting and for restating same.

There was a glaring omission from a sentence in my previous post which I will now repair with an amendment.

If you crater in it won't be 'cause the tug fell apart, the driver decided to kick in the turbocharger, dump power, and/or fly under the power lines, the engine ran out of gas or seized, the tow line or weak link broke or didn't, the tug's release was or wasn't actuated or jammed, or the tow line wrapped or carabiner hooked on to your wires.

(...the tug's release... - to save the trouble of going back for a comparison)

Now lemme say some more of what I'm saying...

Yes, there most assuredly are bad situations in which one REALLY needs to stay on tow and not have someone on the other end of the line whose knee-jerk response to every undesirable situation is to squeeze a lever.

Bill/Mike.

At some point during that tow that glider entered the living-on-borrowed-time envelope. It was low and slow. Assuming that the trike was running with a full head of steam - and I'm pretty sure it was - the action that its driver needed to take was to pull in and maintain said steam. That didn't happen.

If tow line tension gets reduced or lost because:
- the tug trades in some speed for altitude;
- the RPMs diminish or stop advertently or in-;
- a lever or lanyard is hit or pulled; or
- a weak link pops
the glider goes from having an angle of attack way too high to having one way way too high. Need I continue?

1996/05/11. Rerun - but apparently one needs to say things over and over.

Four glider pilots - one of them cringing behind a piling, another running full tilt for shore, a third locked out and about to slam into the dock right where Ray Dunmyer is cowering and yours truly had been standing, a fourth applying full throttle to the winch.

Contrary to what the crowd present is anticipating, the glider is able to benefit from the reduced AOA provided by Jonny Thompson enough to get the starboard wing tip flying more on par with its mirror image and Lawrence Battaile not only survives but is able to get up and make a few passes soaring the tree line at Colington Island.

Neither a cut engine, flimsy weak link, three-string release, hook knife, nor philosophy of a rope donation being a panacea would have been a positive contribution to the situation.

Brian Vant-Hull - 2007/08/03 19:34:15 UTC

Now THAT's interesting enough to suck me back in.

Jim...I concede that Tad's saying that staying on tow is sometimes healthier than getting off. Wasn't expecting that, you read it right I read it wrong.

But I see what he's saying. We tow-launch with a nose angle that in nearly all other circumstances would send us into a stall. The only thing that keeps us going is a tug that obstinately refuses to let the increased drag slow us down so much we lose lift. We're going fast enough when we release from tow that we recover from stall before we drop below 1 g of lift, so don't go into a dive.

Maybe if the nose gets too high releasing from tow is dangerous?

I leave this up to the very experienced tow-meisters to weigh in on. Except for the normally high nose angle I'd say being off tow is safer too.

Jim Rooney - 2007/08/04 10:43:15 UTC

Maybe if the nose gets too high releasing from tow is dangerous?

No.
If you're that high on tow, you've put ME in harms way. You're high, you've got altitude to save yourself with... you're driving me into the ground (at near stall speeds for me btw).

This is one of the prime situations where I will pass out ropes. The other is low level lockout, in case you're interested.

Rest assured, if you get the rope, you've scared the hell out of me. I don't want to smash into the earth, and I don't want you to smash in either.

Tad Eareckson - 2007/08/04 14:32:21 UTC

Correction for previous. Needs to read -

If tow line tension gets misdirected, reduced, or lost because:...

No, Brian, you read it right.

My 2007/08/01 response to Bacil was about the irrelevancy of everything in front of the parts which normally stay with the glider to its future resale value provided its pilot is doing things right.

My post from yesterday addressed situations in which the glider pilots had not met that condition and was a refutation of the philosophy that a dead tow line is invariably a good tow line.

In Example A the pilots allowed the glider to get too slow.

In B the pilot had failed to notice that the breeze wasn't blowing the right way on his starboard wingtip before he gave the thumb's up.

Need to clear up some definitions.

Yeah, the nose is higher when you're leaving the cart at Ridgely than when strolling into the breeze at Woodstock. But the angle of attack - and thus drag to lift ratio - isn't.

Let's see if we can round up enough asteroids to squash together and make a new planet 1.5 times the mass of this one - call it Thor (we'll have to leave one rock out there big enough to end the reign of Homo sapiens and give this planet a fighting chance).

You blindfold the glider and haul it up behind a Dragonfly. It has gravity pulling it straight down and the tug pulling it, with about half the force, straight ahead. It doesn't know the forces are coming from two different sources so it averages their strengths and directions, figures that it's flying over planet Thor and straight down is thirty degrees forward of what it would be minus the blindfold, and trims accordingly. The pitch attitude is thus thirty degrees higher than normal but the AOA is fine. It's flying faster 'cause it thinks it's heavier.

Snip the tow line and the glider says "Holy Shit! This isn't Thor - this is Earth! And down is way the hell back there!" and immediately adjusts accordingly. If the pilot wasn't holding enough extra speed to allow for an easy transition and Earth gets there before the adjustment is completed...

Neither your pitch attitude, AOA, nor combination of the two tells you anything about the relative positions of glider, tug, and runway.

You can be high on pitch, AOA, and position and nosing the tug into the ground.

You can be high on pitch, AOA, and low on position and nosing the tug into the sky. This was the scenario progressing in Example A.

You can be high on pitch, AOA, and in excellent position if you've just forced the glider off the cart. In those circumstances you really do not want to be off tow.

Jim Rooney - 2008/02/25 02:59:11 UTC

meg·a·lo·ma·ni·a (měg'ə-lō-mā'nē-ə, -mān'yə) Pronunciation Key
n.
1. A psychopathological condition characterized by delusional fantasies of wealth, power, or omnipotence.
2. An obsession with grandiose or extravagant things or actions.

Oh, I don't know... sounds pretty spot on to me.
Tad thinks a bit too highly of himself and generally detests everyone else.

But yeah, no argument on the asshole part.
I'm a pretty easy going guy and he irritates me to no end.
(which is why I now block his posts)

Lauren Tjaden - 2008/07/21 14:27:04 UTC

Thanks for the good wishes, everyone. I feel as if I have let everyone down, and myself as well, but I am walking away from this one.

Zapata has delivered as promised, day after day with howling winds and good lift, where flights of over 100 miles (and much more) are possible. I am just not having much fun. I guess it comes down to a simpler truth; I am chicken. I dislike flying low over tiny LZs -- though the glider does not generally glide very far in the high wind. I am scared of being alone in the desert, too. On a positive note, I have gotten much more comfortable with towing in wind. I have seen many wild animals, too.

Yesterday I chased Paul again. The tow rope weak link broke when Paul locked out and the weak link he got from Tad did not break. Russell said it was about the worst he has ever had his tail pulled around. Anyhow, I would advise against those weak links, though Tad's barrel releases do seem better able to release under stress. After Russell got a new rope and Paul recovered, he was late leaving and got trapped under some cirrus.

He flew about 50 miles until he got stuck by the airspace at Laredo. The retrieve was much better, though I had to climb an 8 foot deer fence with the cart strapped to my back and hike through the wilderness for about a mile in 100 degree temps. Actually it was kind of pretty and not terrifying because I had plenty of daylight, though I did scream like a little baby when I startled some Javelina (little piggy creatures with tusks).

On the way out we ran into a trucker bringing in supplies for the gas well. He actually understood my Spanish. He turned the rig around in the desert and put our stuff on it and drove us out. He wouldn't take a nickle, either.

I guess we would have figured out how to drag the glider over the 8 foot fence but it wasn't going to be pretty.

So our navigation tools are much better now and our radios rock and I can tow in kick-ass wind without getting worried, and on pavement, too. Now I am going to visit my sister in Colorado and her baby -- Elle LAUREN!

I look forward to flying in Big Springs with Paul and hopefully redeeming myself while flying over a place with roads and fields.

BTW-- one other good note. Pete L is really really great and called offering to help drag Paul out of the desert that horrible night, and he has just been so kind and supportive. He's had some great flights, too.

Paul Tjaden - 2008/07/22 04:32:22 UTC

Hey Guys,

Once again, a couple more thoughts from Paul. The lockout Lauren mentioned was precipitated by my attempt to pull on more VG while on tow. I have done this before but this time the line wouldn't cleat properly and while I was fighting it, I got clobbered and rolled hard right in a split second. There was a very large noise and jerk as the relatively heavy weak link at the tug broke giving me the rope. I recovered quickly from the wing over and flew back to the field to drop the line and then re-launched after changing to a normal weak link. I have never had a lockout situation happen so quickly and dramatically and had no chance to release as I have always thought I could do. Had the tugs link not broken, things could have gotten very ugly very fast. I still don't like weak links breaking when they shouldn't, but the one I was using was way too strong.

Regarding flying in Zapata: I don't think either of us really realized what is involved. To fly in Zapata, you must accept that you are willing to fly over incredibly desolate terrain with LZ situations ranging from lots of tiny oil and natural gas drilling patches with pipes and tanks all around them to possibilities of landing on roadways where the ditches are extra wide. There are some small pastures but many are covered thickly with cactus. You probably aren't going to die out there but to say that retrieves are inconvenient doesn't begin to tell the story. Yesterday, I was faced with drifting out over a sea of mesquite and cactus at about 800' agl while climbing at about 50 fpm. From my low altitude I could see no LZ's ahead. Many would have gone on and risked landing in that crap. I chose to dive back into the wind and land at the last available LZ and the pick up from there was a huge hassle compared to what most of us know. There are places along the routes north where one must be willing to fly over very large distances of unlandable terrain with only your faith in your skills and fate keep you safe. Could I do it? Yeah....I suppose. Is the potential risk and almost guaranteed hassle worth it? Not to me. I have great respect for the guys that do this but it's just not my thing. Give me a nice competition over this stuff anytime.

Tad Eareckson - 2008/07/22 12:45:07 UTC

Sorry Janni, I gotta step out of character and go with the majority on this one. Records and numbers are really cool but wasn't sounding like much fun. No place for the faint of heart? Hell, isn't that pretty close to the locale of "No Country For Old Men"?

Anyway...

Paul,

I'm pretty sure I gave you a couple of 12 stitch White/Orange bridle links - possibly the next step down but definitely no higher.

I'm REALLY sorry if I neglected to state or failed to make clear at the time that you can pretty much count on getting a couple of hundred feet of Spectra if things get out of kilter enough. But even if the other end of the towline were completely devoid of weak links things would only have gotten another 20 pounds and millisecond or two worth of ugly - assuming Russell had a double loop of Greenspot up front.

The double loop incorporated in the relatively long Dragonfly bridle blows at close to 400 pounds of towline tension and the White/Orange fails very close to 420 - so what you felt was about what you would've had - minus about a fat house cat.

There are, however, five 35 pound increments available below what you were using - 385, 350, 315, 280, and 245. That gets you below what a single loop of Greenspot on a one point bridle would do - 280 - if it were reliable - which, as we all know all too well, it ain't.

If you're interested in dumbing down from what you were and up from what you are using - pick a number and I'll be happy to send you a couple. Otherwise I'd recommend just using a double loop. That'll dial you down to about one and a third Gs.

Tad Eareckson - 2008/07/29 12:45:22 UTC

http://groups.yahoo.com/group/skysailingtowing/message/4597
Weaklinks

Donnell Hewett - 2005/02/08 23:28:13 UTC
4597

Sorry, but I simply cannot stay out of this lively discussion on weaklinks.

Concerning that topic, I am firmly convinced of the following points:

1. Every towing system, without exception, contains a weaklink. It may be a string or mechanical device deliberately inserted into the towline, the towline itself, the release mechanism, the flying wires of the glider, the pilot's harness (when body towing), or some other component of the pilot-glider-tug system. But something eventually is going to be the first thing to break. That thing is the weaklink.

2. Of all of these options, the ONLY PROVEN ACCEPTABLY SAFE weaklink is a string deliberately inserted into the towline which consistently breaks at a known and specified tension.

3. The sole purpose and function of this weaklink is to limit the towline tension to a manageable level, i.e. a level such that the pilot can still maintain control of the aircraft in the event that the weaklink breaks.

4. The appropriate strength of a weaklink depends upon pilot skill. A skillful pilot can maintain control when a stronger weaklink breaks whereas a less skillful pilot cannot. As a general rule, a beginning pilot should limit his towline tension to 1/2-g and an experienced pilot to 1-g. Only highly experienced pilots qualified to perform aerobatics while on tow should use a 2-g or stronger weaklink while being pulled forward (such as when aerotowing).

5. The appropriate strength of a weaklink depends upon the type of towing system used. Different strength weaklinks should be used for foot-launched ground towing, platform towing, aerotowing, boat towing, etc. As a general rule, forward pulling systems such as aerotowing, foot-launch ground towing, etc. should use 1-g weaklinks or less. Consistently downward pulling systems such as platform launch can go as high as 2-gs.

6. The appropriate strength of a weaklink does not depend upon weather conditions or the flight attitude of the glider (turbulence, wind gradient, lockouts, etc.). It is impossible to design a weaklink to release the pilot when he looses flight control because there is no correlation between towline tension and flight control. (A pilot may be in perfect control under high tension but out of control under low tension.) A weak link can only be designed to release the glider under the worst possible conditions before the towing forces exceed the limits of safe recovery when the weaklink breaks.

7. The appropriate strength of a weaklink should always be tested on the ground, not in the air. For example, if a weaklink is tested on the ground to consistently break at 1-g, then you can be certain it will do the same thing in flight. Therefore, if this ground-tested weaklink keeps breaking inconveniently while aerotowing, you can be certain that the problem is not the strength of the weaklink. The problem is with something else concerning the towing system, the flying technique, or the flight conditions. For example, if there is enough thermal activity that the tug and glider enter different air causing the towline to go slack, then there is also sufficient difference in the air to cause the towline to tighten and the tension to increase rapidly. Unless there is sufficient stretch in the towline to allow a skilled pilot time to compensate for this rapid increase in tension, it will quickly increase beyond the weaklink breaking point even while the pilot is in perfect control. If the problem is a lack of stretch of towline, the system needs changing. If the problem is flying technique, the pilot needs more training. If the problem is excessive air turbulence, flight operations need to be suspended. Simply switching to a stronger weaklink does not make this situation better, it simply makes things more dangerous when that weaklink does not break and when (not if) it does break.

Donnell Hewett
Department of Physics
Texas A&M University-Kingsville

The author of that post - for the benefit of anyone who doesn't know already - was the guy who figured out about a quarter century ago that you don't configure a hang gliding tow bridle to anchor on the three corners of the control frame triangle and in so doing got himself censored out of Hang Gliding magazine and bagged a doctorate in physics.

Nevertheless - I gotta take issue with a few items, minor and major.
---
Point 1
Excellent. No problem there. I would just amend it to state that I'm pretty comfortable stating that the next thing to go in the absence of weak links and possibly any fabric between tug and glider is gonna be the Dragonfly's tow mast (extending from the rudder post).

Point 2
Yeah, the ends of the towline are really excellent places to install weak links and that's where USHGA requires them. We ignore that directive but, what the hell, incorporation in bridles can safely substitute IF done right.
The weak link doesn't have to be a string. The metal inserts of the Tost system and the stitching of the shear links do the job better.

Point 3
Yeah on the manageable level, nah on the caveat (more later). Here's where sailplanes, the FAA, and Dynamic Flight get it right and damn near everyone everyone else starts getting it wrong.

Point 4
Think about it.
A single loop of Greenspot on the end of my two point bridle gives me 0.76 Gs at best - and 0.39 Gs at worst. I can and have done some pretty cool aerobatics on tow within that limitation. I've also busted off of tow straight and level in glassy air.
Has anyone ever heard of an accident anywhere at any time in the history of center of mass towing precipitated by aerobatics at altitude?
And how come the FAA doesn't correlate sailplane pilot proficiency with weak link strength? And as far as I'm concerned a 0.5 G weak link shouldn't be anywhere near a towline regardless of who's on the ends.
There's also a weak link in pilot competency and it ain't his ability to perform aerobatics - it's his ability to terminate the tow before the need to recover from a wingover is exacted. Up high that proficiency doesn't much matter - one can pick things up as one goes along. But down low one can't learn anything while trying to fly through topsoil.

Point 5
I think this is totally backwards.
Downward pulling systems are generally tension controlled, i.e. in the normal course of events it's impossible for the weak link to be subjected to much more than an ambient preset load. Those folk tend not to break them.
Aerotowing is speed controlled, there ain't hardly nuthin' to dampen tension fluctuations, and in good air those fluctuations can and tend to be huge while remaining well within the range of recoverability. We break them all the time.

Point 6
Rat own - 'cept for the implication of the last sentence. If one still has an intact glider and enough altitude one is always well within the limits of safe recovery.

Point 7
Again - If the weak link fails before the glider breaks it's done its job.
At the other end of the scale... Unnecessary weak link breaks tend to be pains in the ass at best and dangerous at worst.

Saturday I asked Sunny how many weak link breaks had occurred in the history of Highland Aerosports which were both desired and necessary - desired because the bubble had been lost and necessary because there was insufficient opportunity for the pilot to react. Got the answer I expected - ZERO. That adds up to a lot of needless and expensive pain in the ass over the course of nine and a half seasons.

And that's precisely the same number of occasions I've heard of anyone ever anywhere having a problem due to a weak link that was too strong.

As I've said before... A weak link should be thought of almost exactly the same as a parachute - you always wanna have one but you NEVER wanna have to use it. And if its use is required it's almost invariably as a consequence of pilot error.

Now lemme think... CHGA-MHGA sorta sites - within the periphery of Manquin, Daniels, North Fork Mountain, Cumberland, Breezewood, McConnellsburg, Ridgely - the number of deliberate parachute deployments we've had for nonaerobatic flights since the days of bamboo have been - what - ZERO?

Paul's of 2008/07/20 is the ONLY AT weak link break I've EVER heard of ANYWHERE that was both desired and necessary and even in that scenario there were pilot choices made that probably contributed to the severity of the lockout.

Whenever one takes a hand off the basetube - to actuate a release, punch a button on an instrument, change a VG setting, or reach for a downtube for examples - one compromises one's control of the aircraft. Paul already had Items 3 and 1 working against him and both of those were options.

Just to be clear on this - these are not criticisms. If you're weak link protected and out of striking distance from the ground there's not a lot that can happen to you as long as you have some measure of towline tension. When Steve, Hugh, or I are towing one point we have to reach for the release after we get to safe altitude and I frequently go to the VG lever on tow (and I've put myself on my ear before cranking from off to on but have never popped off as a result).

And he got severely hammered at the precise moment Murphy said he would.

So you have an extremely high AT time pilot flying in world record thermal conditions with two or three things going wrong at the same time and you get a probable once in a lifetime weak link break. Yeah, that sounds about right.

Again - I disagree that that 420 pound / 1.4 G weak link was too strong. It was 180 pounds / 0.6 Gs below the USHGA/FAA limit. The reason he got the Spectra was 'cause the weak link on the tug end was only up to the task enough for Karen to take full advantage of her weak link range allowance. To make it up to the limit for the heaviest solo glider it needs to be able to handle an additional 300 pounds of towline tension.

But I decided that if I were ever gonna break another weak link it wouldn't be because the one on the glider end wasn't up to snuff. I don't have any control over what goes on the front end but I'd rather take the one in several hundred chance of getting the rope over the course of a long towing career than put up with the bullshit I've experienced before and that's what I continue to recommend to others.

Going out on a limb time...

With a finger or set of incisors on the trigger the lockout that can't be terminated well before a 0.8 G weak link fails has yet to be invented. Yet the culture - as a whole - clings like a barnacle to the mistaken belief that, regardless of one's weight, a single loop of 130 pound Greenspot is the mandatory component to ensure that one doesn't put a dent in the runway and ignores the technology that actually does accomplish that goal.

And it's entirely possible to be low and in trouble in situations in which one REALLY would rather the weak link held.

If one is locking out but still climbing it might be advisable to stick around long enough to gain the altitude required to get the glider level again.

If one is stalling towline tension is one's friend.

P.S. On the afternoon of 2008/02/02 Carlos was at a grand behind a Ridgely tug when he got hammered and locked out to the left. He fell in that direction so far that he was unable to reach the bicycle brake lever mounted on his starboard downtube and somehow managed to get the rope despite the fact that his bridle was fitted with a single loop of Greenspot and the Dragonfly was packing a double. So... the death and taxes thing.

P.P.S. With respect to the ubiquitous brake lever actuated releases the way they are almost always configured, doesn't that one incident pretty much make hash out of the following?

PART 104 - PILOT PROFICIENCY SYSTEM
11. USHPA HANG GLIDING AERO TOW RATINGS
02. USHPA Aero Vehicle Requirements

F. A release must be placed at the hang glider end of the tow line within easy reach of the pilot...

Marc Fink - 2008/07/29 16:07:15 UTC

Hewett's point 7 is about the best analysis of towing and the relationship to weak links that I have ever read anywhere.

Matthew Graham - 2008/07/29 17:32:11 UTC

I mount the brake lever on the base tube near one corner-- I can easily pull the handle with two fingers without letting go of the base tube. I have a round comfort bar base tube. However, I've also mounted the brake lever on the new flat WW speed bar base tubes and it works just the same.

Tad Eareckson - 2008/07/30 22:28:40 UTC

Marc,

My heroes in this sport are the folk who with enough brains to step back from the crowd, look at what it's doing, and say waydaminute. Donnell Hewett is way up there on my list. I have a pretty high regard for what Peter Birren has done as well.

But I get the feeling that neither of these individuals has spent much time around a high volume Dragonfly operation and consequently don't have a good feel for where we're actually having problems and where we ain't - despite what looks good on paper.

A little more on the issues addressed in Point 7 with respect to Dragonfly towing in general and Ridgely in particular...

1. Weak Link Strength

Yeah, weak link strength should always be tested on the ground. One big problem was that nobody ever did that for many years. It was just accepted that a single loop of 130 pound Greenspot tied with a Fisherman's Knot and installed on a bridle with a Double Lark's Head blew at (130*2=) 260 pounds and - obviously - a double loop would hold to 520. Then, finally somebody (me) actually tested them on the ground and said nope - 140 and 200.

So what that means is that nobody much heavier than Karen - and more recently my small but growing band of shear link rebels - is actually flying the 1 G or better weak link that Doctor Hewett uses in his example.

The other big problem is... The more you move up the scale from Karen - 200 - to me - 320 pounds - the less you can rely on that weak link to retain that 140 pound integrity. The peak loading that occurs when the dolly starts rolling can degrade the damned thing to 72 pounds by the time you get airborne. So - actually - no, you can't be certain it will do in flight what it did on the test rig. Just about all of us can be pretty much certain it won't.

2. Towing System

Our towing system is not the cause of any weak link breaks. If you hook up behind a Ridgely tug using a bridle assembly they've sold you every significant portion of the tow system between Dragonfly and glider is low stretch Spectra. You start throwing nylon into the mix you start slowing your climb, burning more gas, and introducing the possibility of something recoiling into your face.

3. Flying Technique

The flying technique of NOBODY is bad enough to justify a weak link break.

4. Flight Conditions

The more the flight conditions suck on tow the more you want to be able to stay on tow long enough to make it to a workable altitude. If the weak link blows before you get to the point of no return (a la Janni 2008/07/19) it wasn't strong enough. And if an adequate weak link blows before you can actuate your release you need to do some serious thinking about your response capability. It should not be a "when (not if)" situation. It is something that the average pilot should never experience.

And I totally disagree with the statement that - within the 0.8 to 2.0 G range - switching to a stronger weak link makes a tow more dangerous. All it means is that one is very likely to experience a more interesting wingover at failure.

In actual practice it's the under strength weak links that make things more dangerous. On this point Paul was in agreement a couple of months ago. And, as far as I know, Doctor Hewett has never had anything to say with respect to this end of the spectrum.

Towing up behind a Dragonfly is a lot safer than landing and a helluva lot safer than landing in the air which it has just powered through.

A little more dissection...

Point 3
"The sole purpose and function..." Notice that that paragraph makes no reference to preventing one from slamming in in the course of a low level lockout. And in nothing else of his I've seen is that popular fallacy reinforced.

Point 4
A 1 G weak link is probably OK. 1.4 Gs marks the center of the safety range. The only excuse for towing 2 Gs is 'cause you don't have anything lower 'cause by the time you're stressing a 1.4 G weak link you're so far gone that there's no freakin' way you're gonna get the tow back even if you are John Heiney.

If Doctor Hewett is right on all this stuff than the FAA and USHGA are wrong.

The best analysis of towing and the relationship to weak links that I have ever read anywhere is:

http://www.dynamicflight.com.au/Reading/WeakLinks.html

and what they say is in accordance with the FAA and USHGA and significantly at odds with the skysailingtowing post. If you or anyone can punch any holes in what Dynamic Flight's page I'd really like to know what they are.

A few more data points with respect to sub 1 G weak links...

On 2008/06/02 Lauren popped one high enough to get her away from launch but too low to turn back and land and spent a lot of valuable ECC Round 2 time carrying her glider back from the west end of the runway.

Later that competition I watched a Dragonfly blast off from the flight line with only an empty carabiner on the end of the towline.

Bob Buchanan recently experienced ten consecutive weak link breaks attempting to get his Exxtacy to 2500 feet.

Bob Koshmaryk recently got dust devilled so bad on launch that his Discus was dragging a tip and his weak link didn't break. He was able to fly out of the situation successfully.

Matthew,

The bicycle brake lever is - along with curved pin barrel releases - amongst the worst ideas ever to be inflicted on the arena of aerotowing. It's just so much more draggy crap than is necessary to do the job.

However... If I were forced to use one - yes - I'd put it on the basetube where I could keep a finger or two on it at least long enough to get to safe altitude.

Although it's something you'd prefer not to have in front of or below your face or chest when you pancake in I think it looks a lot more dangerous than it is.

Marc has a scary story about a bridle snagging on a basetube mounted instrument and having his positive pitch range dangerously limited for almost too much time. Although I would definitely have concerns about that sort of thing I'd say that they are totally overridden by the plus side of being positive of the ability to release in nothing more than decision and reaction time.

Kirk Lewis - 2008/10/28 02:03:57 UTC

My tows have been pretty consistent and so far my weak links have seemed to go at times that weren't the result of being out of position... the weak link had just been worn down and finally snapped. My question is... when should you replace a weak link, if at all? It seems silly to just let the weak link eventually snap due to wear, considering the time spent + cost involved for those towing who waste a takeoff. Do any of you try to replace your weak link on a regular basis?

Kevin Carter - 2008/10/28 02:09:26 UTC

Kirk, what is your weight and S2 size? I usually go a season before replacing a weak link and then only because it shows some wear. Weak links should never break in normal towing, unless the conditions are very strong.

Kirk Lewis - 2008/10/28 03:36:02 UTC

I flew my sport 2, 135, this weekend, but until now I've been flying a falcon 145. This season I'd say I've had about 4 weak link breaks total, but I've been towing more than most people. I probably average about 4 tows a day, and if conditions are good I go sat and sunday. This last weekend I was about 1500 feet up and the weak link broke for no particular reason that I could see. The others have been at the point that you start to hit turbulence due to wind coming over the trees. I have noticed that after a few tows I can see the link becoming a bit frayed...

Kirk Lewis - 2008/10/28 03:36:41 UTC

Oh and I left out my wieght: 145

Jim Rooney - 2008/10/28 09:43:00 UTC

You're using a top release, which changes the equation a bit. The metal clip can wear the weaklink, esp depending on how you release. To minimize this, be sure to pull in before releasing which will relieve tension on the weaklink and let it fall out. Our average for tandems is one in fivehundred (guess) if we release well (pulling in to slack the line). If not, we have to change them more often.

How you tow can also degrade things. The more you do it, the better you'll get about anticipating high shock load situations and minimizing them... example... when you're about to slam into the propwash on liftoff, pull in. This will lower the loading on the lines and allow the glider to take the jarring instead. There are other points on tow that this happens, but that's the most obvious example.

With a top release, every month isn't a bad idea.
With protowing... I can't remember the last time I changed mine.

It's just a piece of string (we've got tons) and we're happy to help you change it.

Jim Rooney - 2008/10/28 09:48:28 UTC

An other excellent solution is to pick up one of Bobby's top releases...
http://www.liteflite.com.au/ProductsBridleTowRelease.aspx

His use a barrel release on the top as well as shoulders so the weaklink wear is greatly reduced. (still a good idea to pull in)

Kirk Lewis - 2008/10/28 12:09:48 UTC

Ahh very good advice Jim, I'll give that a try. I've certainly noticed visible wear on the weak link after a few tows, so pulling in before release should help a lot. I usually release and then pull in LOL.

Tad Eareckson - 2008/10/28 16:42:10 UTC

Yeah, you knew I would.

Kirk,

I'm gonna call your Sport 2 hookup weight 230 pounds.

A single loop of Greenspot at the top end of your bridle will give you about 1.0 Gs - in theory. If the theory was any good that would still be a little marginal.

Too see what's wrong with the theory go to:

http://ozreport.com/forum/viewtopic.php?t=13573

Any sane understanding of aerotowing floors the allowable weak link strength at 0.8 Gs and both the USHPA and FAA cap it at 2.0. The middle of that safety range is 1.4. And that's what you should be shooting for.

Karen tows at 1.22 Gs and has never popped a link nor been in a position in which she needed or wanted to. You start reducing that margin - you start asking for problems. Those old fuzzy things you've been using are blowing at about 0.5.

Doubling the loop does not - as one might well think - double the strength. It goes from about 140 to 200 pounds. For you and your two point bridle that translates to 1.5 Gs - very close to where you wanna be and well under the USHPA limit.

I strongly recommend you do that. If you want a second opinion...

http://www.dynamicflight.com.au/WeakLinks.html

That comes from one of the small minority of the hang gliding culture which really understands weak links.

You should be breaking them at just about the same frequency that you're deploying your parachute. Which is - right - never. The same frequency that Karen and I do.

I'll take a little issue with Kevin here and state that they should never break until you NEED them to - and you should've released well before you get to that point. Neither strong conditions nor turbulence off the trees should be doing it. Don't allow an understrength weak link to be making your decisions for you.

If you don't trust us... At the very least take a magnifying glass to your weak link after each flight and retire it as soon as you detect broken fibers protruding from the string. Relaunches, as you note, are enormously expensive to everyone concerned - very much including the people waiting in line and watching the soaring window evaporate.

With respect to:

http://www.liteflite.com.au/ProductsBridleTowRelease.aspx

That's a step in the right direction but any release based on a curved pin is junk. Go to:

http://www.flickr.com/photos/aerotowrelease/

temp set, to see why.

Several years ago I swapped out my spinnaker shackle for a straight pin barrel release and have had excellent results. If you want something very clean and efficient I can do an installation on your glider. Or I'd be happy to walk you through it if you wanna do it yourself.

If you're not opposed to extra cable in the wind...

Bug the HELL out of toto's_ride. Tim developed an EXCELLENT slap-on release. There should be one in the shop at Ridgely you can take a look at - probably even take for a test drive. He's had a tight year but I've been desperate to get my hands on one so's I can get some photos up.

Tim,

If you're listening, you might want to get a restraining order. I'm considering stalking.

But really, can we get together soon and do a tradeoff? I've been trying to do this for over a year now. I'm quite happy to walk from a Metro station.

Kevin,

Three years and a month ago you wrote:

http://www.chgpa.org/forums/viewtopic.php?f=2&t=1079
$15 pacifiers

Kevin Carter - 2005/09/24 21:49:39 UTC

One pilot in the Texas Open had three premature releases in a row with glider damage on all three and different degrees of pilot injury. I myself have had a low level release that caused minor injury.

Can I get some more details on those? In particular, were those weak link breaks, release malfunctions, or both. If malfunctions - what was going wrong?

Thanks

P.S.

Those friends of your dad's who recovered my parrot were Chip and Mary Ann Hines.

Last month I tracked down their house when I needed a sitter but a next door neighbor from whom I got their last name and the information said that they had moved to Florida.

Kevin Carter - 2008/10/28 23:10:52 UTC

Kirk, tow the S2 off the shoulders Its fun.

Tad, the pilot with three in a row was not using proper technique. Popping (HARD) out of the cart, then not pulling in enough. He tested fate and finally pounded hard enough to make his glider not flyable. It was extreme, an image I won't forget for a long time.

I am not sure what my release was or the "injury." Apparently that memory was not burned so vividly. I might have been flying barefoot. My harness back then was too small for my feet and I did that sometimes. If you send me the link maybe the context will fill in the memory blanks. Then again, I know one time I had a trike with a release failure at his end. Might have been that. Jeff Hunt comes up from Mexico with Curt's old trike. He is a good guy and since I love towing fast, I never shy from the trike. Its more work, and the climbs are slower, but who cares. They had recently repaired the mechanism after it was damaged and apparently it still needed some adjustments to not release during extreme movements of the control bar on the trike. I'm not sure if that is the same event, send me the rest of the story and I will confirm.

Matthew Graham - 2008/10/29 03:32:52 UTC

Tad,

YOU ARE THE WEAKEST LINK!

Goodbye.

Tad Eareckson - 2008/10/29 10:30:27 UTC

Kirk,

Yeah, like Kevin says, if you have a glider you can tow one point - and you do - that solves a lot of problems - including money.

In that configuration you're gonna get about 1.22 Gs from a (new) single loop, 1.74 with a double. I think the single will be fine.

Kevin,

http://www.chgpa.org/forums/viewtopic.php?f=2&t=1079
$15 pacifiers

- second page.

Thanks very much for the details. Those should prove very useful in a discussion I'm having on skysailingtowing.

Matthew,

Where the hell did that come from?

Kirk Lewis - 2008/10/29 13:43:34 UTC

Thanks for all the suggestions everybody. I think I'll start first with better tow technique, but if that doesn't do it I'll start looking into the other options you guys mentioned. I certainly don't want to change too much too quickly considering I'm on a new glider

Jim Rooney - 2008/10/29 16:20:20 UTC

I certainly don't want to change too much too quickly considering I'm on a new glider

You've learned well young Skywaker

Eventually... when you're really comfortable towing.... you can start protowing (shoulder only).
But, yeah, keep with the "not too much too fast" attitude. It'll serve you well.

Kevin Carter - 2008/10/29 23:22:15 UTC

Tad,

Thanks for the link. Rereading it didn't shed any new light on the memory. I think it was hardware failure on the trike. Whatever injury I got must have been minor, like a pulled muscle or stubbed toe. It wasn't significant because it didn't seem to alter my flying at all. Later that week I blew it big time doing loops and threw the dirty laundry.

Mark Cavanaugh - 2008/10/30 04:33:48 UTC

This has been (dare I say it???) a fairly civilized and calm discussion, with mention
of BOTH weak links and releases. Imagine that!

In the interests of continuing that trend, please people, no one-liner 'zinger posts'.
The intent might be for sarcastic humor... But they don't contribute anything, so
please keep 'em to yourself. Or take it to the General Discussion forum.

Thanks for your consideration!

**reluctant-moderator hat off**

Tim Hinkel - 2008/10/30 20:38:14 UTC

Tad,
thanks for the love. Just about ready to put a couple of these gizmos in a box, dim the lights and see if we can't get a few more of them running around by springtime. Hope to be at Ridgeley on Saturday (weather willing), chance I'll see you there?

Tad Eareckson - 2008/10/30 22:55:42 UTC

Mark,

Nah, I get more unprovoked personal attack out of that. Kinda strange, considering the source.

Kevin,

Thanks much for the research and educated guess. Good enough.

Kirk,

Yeah, whatever you do on tow that moderates the tow tension is great - that's how you should be flying anyway.

But you shouldn't have to be doing it to mollycoddle your weak link. If it can be degraded by as little as those sorts of tension irregularities it's dangerously understrength.

Let's take a look at Kevin's Texas Open guy - we'll call him Tog and make him 280 pounds.

Agreed - his launch technique is shoddy. Kinda surprising 'cause this isn't something that takes a whole lot of brains and/or skill. Maybe he did too much truck towing.

I'd be amazed if he was pulling more than 0.6 Gs - 168 pounds, 43 over normal - when he was popping those links.

Nobody who has a clue will recommend anything under 0.8. If you did that in a sailplane you'd be operating illegally. And I think that in a hang glider you're asking for trouble until you're very comfortably over 1.0.

Let's rewind the tape.

This time we're gonna remove any and all weak links from the vicinities of both ends of the tow line. Not a great idea - granted - but, then again, neither is leaving your parachute in the closet. See above.

Tog's launch still sucks but he only has to do one of them and he gets up and away no problem.

That evening you show him the video tape and chew him out. He's not all scraped and bruised and he still has a glider to fly so tomorrow he gets a chance to improve.

The one you popped at 1500 feet last weekend went at about 0.54 Gs. That's not even close to being safe. Triple that would have been a bit over ideal.

Some things you certainly don't want to change too much too quickly. You probably don't want to abruptly transition from a Falcon at Taylor STFI at 8 to a bladewing at Woodstock 15 gusting to 30 out of the west (mostly).

Other things you DO want to change immediately because they have no bearing on the way you control the glider and make you safer. Examples of advisable abrupt alterations: Bare hands to gloves, T-shirt to jacket, shorts to slacks, placebo wheels to big pneumatic jobs, open to full face helmet, downtube to basetube actuated release...

0.6 to 1.2-1.5 G weak link. Getting spat off tow at the point that you start to hit turbulence due to wind coming over the trees is not making you safer.

Tim!,

You're still breathing!

I took the racks off the car for the season on Sunday but may reboot if the weather looks promising.

If not, and you're happy with sled stuff - how 'bout a rendezvous and car pool from Annapolis?

My E-ZPass and I'm your slave for the day - battens and everything.

Somebody on the Oz Report Forum just made the mistake of broaching the subject and I'm girding to go majorly postal. I REALLY wanna get those photos up so's the unwashed masses can finally get a clue as to how to do things right.

Is yahoo still the best way to talk?

Kevin Carter - 2008/10/31 01:12:56 UTC

Tad,

I'm sorry if it weakens your argument but in Tog's case it is quite possibly good that his weak link kept breaking. Maybe I am not doing enough to trash dear ole "Tog" in an open forum. He was an idiot, unqualified and unfamiliar. The type that causes meet directors to make the big threats of meet expulsion for pilots who are not honest about their tow skills/experience. The problem seems to be worse when pilots travel great distances from unfamiliar HG circles. In those cases there is less self regulation in the community. In "Tog's" case he went a long way to perpetuate the stereotype. He did the bare minumum to obtain his tow credentials. Like when one flight park told him he couldn't tow a topless midday or in a meet without showing up early for (alot) more practice, he just found another FP that would tow him. Every once in awhile a talented mountain pilot shows up at meets and expects the red carpet to roll out for them because they are with a bunch of their buddies who have more tow experience. Its always stressfull for the members of the tow operation.

In "Tog's" case the weaklink was giving up when he was low without many options. That sucks, but how about the tow pilot at the other end of the rope that might be getting his airframe shoved into the tarmac? A weaker weak link can be bad but if you catch a ride to an Open Meet on the short bus a stronger one can be muich worse. For a pilot who counts on a WL to make decisions for them (ie Tog who can't pick the right time to pull in) weaker is better. Keeping a bonehead like that on line is only giving him an opportunity to strain a weaklink on roll.

It could be argued that a "good pilot" (I think I have met maybe a couple dozen max) is better off with a stronger WL to help them manage the dynamics of towing in bigger air. For those guys a premature release is not good because it happened when the air was highly dynamic, that doesn't always mean the glider is out of control (like most WL breaks). Sometimes you keep the glider in the right place but the line just goes too slack (ie towing behind a trike). These "good guys" are the ones you never see break a weaklink in normal conditions. Probably because in the rare situation where they get out of wack, they pull the release BEFORE a lockout because they know many moments before that the glider just isn't going to come back from that angle. Not many guys fall into that category.

I am beging too argumentative. When it comes to setting the bar for towing skill I say more then one weaklink break per year should require some soul searching. Either glider choice, training level, or choice of conditions. Those things just should not be breaking!

Tad, you mission used to be hair trigger releases. I'm not current on my forum freetime education but it sounds like the mission now is to strengthen weak links? I don't post much, but my mission this week and most weeks, is raising pilot standards and skill. Most all of my opinions have that mission as the agenda. Hair trigger releases are bad for good pilots who count on the line, and strong weak links are bad for any pilot that cannot manage tow forces themselves in their "conditions envelope." One weak link per 100 tows seems like an appropriate goal.

Tad Eareckson - 2008/10/31 13:52:46 UTC

No, Kevin, I love it when people attempt to weaken my argument. If they're wrong - they can learn something. If I'm wrong - I do.

First off - small bone to pick...

You first represented the Tog Series as evidence of why it was rather important to remain on tow until comfortably above the crap zone. And for these past three years I've thought quite a bit about this report in that context and under the delusion that he was just an innocent victim of understrength links.

You've done a bit of a flip with your first sentence on this last post.

(Permission to treat witness as hostile, Your Honor?)

No big deal. Both the imagined and actual circumstances are worth considering and addressing and there's nothing either way that alters my thinking or position.

OK, I seem to overestimated Tog's skills and, apparently, learning potential. Probably also underestimated the jerkiness of his launch.

In light of this expanded information my take on Tog is not to dumb down his weak link - but rather to dumb down his card. There's no freakin' way he should've gotten by USHPA SOP 12-02.10:C:4. No tikky, no towy. End of that problem.

I've recently been scrapping with Donnell Hewett on the skysailingtowing forum 'cause in his Skyting Criteria he asserts that the weak link strength must be scaled to pilot skill. My position is that an understrength weak link is as dangerous to a Hang Two as it is to a Five.

The glider is low, rolled hard, and off to the side at the end/beginning of an oscillation cycle. The link pops. Whachya gonna do?

Several flights ago on an unremarkable day, ten feet off the ground and well down the runway to the east I had my wires go slack (briefly, I'm happy to report).

Shit happens. I'm pretty happy to have an excellent release system and a 1.4 G weak link when it does so's I'm the one making the decisions. (Damn. That sounds disturbingly W-ish.) I'm quite sure that I totally suck by comparison to your Chosen Two Dozen. I'm also just about positive I will never break a weak link and I have a good idea I'm safer getting into the air and under better control than they are. My equipment is better.

With respect to the tug...

ANY glider with ANY weak link capable of sustaining tow is capable of nosing any Dragonfly into the dirt. Karen can do it maxing out her weak link for 243 pounds of tow line tension and a Ridgely tandem can do it with its 348. That's why people should have fingers on triggers - those are the only things that can be relied on to keep situations from going to hell.

...that doesn't always mean the glider is out of control (like most WL breaks).

I disagree (at my peril 'cause you've been around this stuff a helluva lot more than I have - but that has never been the case on the Eastern Shore). The stuff that Kirk is describing is typical. I've been hearing the same from Valerie and Raj - a couple of the other new kids at Ridgely. They tend to be puzzled at first and remark that there was nothing going on with tension or control at the time. Then they "learn" that, well, that's just the way it is and is supposed to and has to be.

And I get all - NO! IF IT'S BREAKING FOR NO REASON IT'S TOO GODDAM WEAK! BEEF IT UP! But their souls are lost already... The myth gains more converts and the cycle continues.

Weak links should only be breaking when you need them to. Not, as above, for no reason - nor while you're working on a correctable problem.

...I say more then one weaklink break per year should require some soul searching.

I'm saying that virtually NO ONE should EVER break a weak link in the course of a flying career. I know of only one partially necessary weak link break in the history of aerotowing and I'm not hearing people flooding the wires with first, second, or third hand accounts of other candidates.

Either glider choice, training level, or choice of conditions.

You're leaving out THE biggie. Nobody should expect to complete a tow with the good ol' one size fits all 0.5 G weak link.

...your mission used to be hair trigger releases.

No. I don't think I ever pushed that publicly. I went through a very brief experimental period tweaking my release system to hair trigger. After about two flights I concluded that that was a bad idea 'cause the last one ended at about a hundred feet when I made a minor adjustment to my grip.

I did - and do - vehemently insist that your AT release system should allow you to get off tow without having to take a hand off the steering wheel and surrender control of the glider. Systems which do that have been flying for many years now just fine, thank you.

My current main thrust is to get this culture in line with what the FAA knows and codifies. And that is that anything under a solid 0.8 G weak link is dangerous and that you don't use a weak link to make your decisions and do your job for you.

...strong weak links are bad for any pilot that cannot manage tow forces themselves in their "conditions envelope."

and any pilot who thinks that a weak link can compensate for his deficiencies is rolling dice - at best. People need to stay in their conditions envelopes - especially near the ground where the tow is most dangerous and the weak link is least likely to do any good.

...my mission this week and most weeks, is raising pilot standards and skill.

Yeah, I think this is totally consistent with what I'm trying to do. That's how you keep from slamming in at the end of a low level lockout. A much better approach than freezing on the basetube and praying that your weak link will fail in time.

My main mission though is to get the equipment up to specs that have been on the books since the beginning of time so those pilots of high standards and skill levels have something with which to work. The best pilot in the world can't pull out of a full luff dive if the reflex bridle and washout tips have been disengaged. Nor can he maintain control of a glider with one hand - especially on tow.

Thanks much for the effort that went into your post. I'll appreciate any feedback for which you have time.

Brian Vant-Hull - 2008/10/31 14:52:37 UTC

I'm curious Tad. Describe a situation for which you feel the weak link is useful. Does the glider have to get caught on a tree, or is there some in-air situation?

Tad Eareckson - 2008/11/01 01:51:26 UTC

Hi Brian,

I like this from Steve Kroop...

http://groups.yahoo.com/group/skysailingtowing/message/4633
Weaklinks and aerotowing (ONLY)

Steve Kroop - 2005/02/10 04:50:59 UTC

Weak links are there to protect the equipment not the glider pilot. Anyone who believes otherwise is setting them selves up for disaster. The pilot activating his or her releases is their way to save themselves. A perfect analogy is the circuit breaker in your home, it is there to protect the wire not what you plug into the wall socket. If anyone does not believe me they can plug their car retrieve 2-way radio into the wall socket and watch it go up in flames with the circuit breaker comfortably remaining in the on position (I hope no one really tries this .

If a lockout goes on for a long time with no one taking any action the weak link kicks in. I no longer fly with the expectation that the weak link will be part of my safety equation - and I'm a lot happier and more confident and comfortable in that mode.

So to answer your question...

I just don't think a weak link is useful - AT ALL.

Same way I don't feel a technique for climbing into your control frame after you've failed to connect to the glider is useful. Just do the damned hook-in check so you're sure you won't need that particular ability.

Matthew Graham - 2008/11/01 03:39:15 UTC

Well, I can think of at least two people who would be alive today if they had used an actual weak link. If you ever decide to stop using weak links altogether, let me know so I can buy a life insurance policy in your name.

Tad Eareckson - 2008/11/01 10:33:03 UTC

Who?

Tad Eareckson - 2008/11/02 14:53:00 UTC

Very sorry to hear the report of your brief flight yesterday and I'm hoping that they're will be no long term consequences.

But, back to the issue...

No.

Their problem was too little tension - not too much.

The root cause of that accident was that they violated Point 09 of 12 of the Skyting Criteria, written about a decade and a half prior.

Group 3 - Practical Implementation

09: Adequate Power

The system must contain a source of power adequate to maintain a safe mode of flight while under tow.

The Dragonfly is the reason we will never again see that sort of accident. The problem wasn't too big a weak link but, rather, too small an engine. The only difference a dumbed down weak link could have possibly made would have been to have cut their lives a few seconds shorter.

Any other candidates?

No, I didn't think so.

Tad Eareckson - 2008/11/03 13:11:17 UTC

(Make that "there".)

Just out of curiosity, Matthew...

Highland Aerosports has launched, near the close of its tenth season, something better than 40,000 tows.

The number of instances in which a weak link break was required for the safety of the flight is - to date - ZERO.

And, as we all know, just about all of the several thousand pops we have had have been totally needless pains in the ass.

Pretty much the only part of the tow which can hurt or kill you is the close to the ground stuff and that's the zone in which a single loop of Greenspot is more likely to precipitate your being mangled than it is to prevent same.

Analogy... Weak links and parachutes are about equal in effectiveness at fifty feet and you don't want either one trying to do its job there.

So, to partially plagiarize Brian's question -

How 'bout YOU describe a situation for which you feel you could come out ahead on the aforementioned insurance policy.

I would suggest you get a good grip on Steve Kroop's statement:

Weak links are there to protect the equipment not the glider pilot.

before you start making investment decisions 'cause with your current understanding of the issue you'd be a lot better off buying lottery tickets. One in seventy-five million is pretty good odds when the alternative is zero in forty thousand (and counting).

I don't expect to hear from Matthew 'cause - in accordance with the time honored glider forum tradition - when he paints himself in a corner he tends to just drop out of the conversation. But I'd be happy to hear from ANYBODY who thinks he has a shot.

Matthew Graham - 2008/11/03 18:40:45 UTC

Gee Tad, Sorry I'm not at your beck and call 24/7. I don't always check out every thread on the forum. I've been otherwise pre-occupied the last couple of day. To answer you question, Bill Bennett and the instructor from Ohio were using a piece of nylon cord and not a weaklink. As to you assertion that a weak link has never saved anyone at Highland, how do you know? If a weak link breaks just prior to a lockout, that is saving someone's life. You are arguing that because weak links sometime's break when the pilot is not in danger that they don't do any good when the pilot's life is in danger. That is beyond absurd.

Janni Papakrivos - 2008/11/03 19:29:05 UTC

A weak link certainly saved my butt on one occasion. I came off the cart crooked in my Litespeed, over-controlled and would have quickly been in a close-to-ground neck-breaking lockout if the weak link hadn't snapped right away. They can't be weak enough in my humble opinion, especially if you fly sluggish top performers.

Tad Eareckson - 2008/11/04 04:20:29 UTC

Hi Matthew,

Thanks much for coming back on. And, again, I'm very sorry you got hurt and wish you the best as far as recovery is concerned.

I don't expect everyone to read everything that comes across the wire, but if one has chosen to participate in a particular conversation...

I don't know - or particularly care, as it's completely irrelevant - what Bill Bennett and Mike Del Signore were using as a weak link but I believe I remember Christy telling me it was a multi-strand job. It was installed between the towline and two point bridle and they were using a three-string installed at the bridle apex with the lanyard running back to the port side of the port pilot which was Bill.

The weak link was reported to have been four to five hundred pounds - which would have put ME - solo - well within USHGA specs. For that tandem ride we're talking a G rating of no more than 1.0 and that's significantly less than what Karen uses.

I wrote about this accident fifteen months ago but - obviously - things haven't sunken in. So here we go again...

It was hot, they were heavy, the trike wasn't up to the job - powerwise. None of those parameters does a whole helluva lot for climb rate. They were unable to stay level with the tug and that deficiency in altitude put them in dangerously close proximity to the wake. They PUSHED OUT to try to keep up and from about that point on were living on borrowed time.

They knew that. They knew that the only thing that was keeping them alive was the minimal tension they were getting through the string and that as soon as either they lost it or the stall progressed - whichever came first - the show was gonna be over. That's why they didn't release and that's why the last thing in the world that they wanted to have happen was a weak link break.

You're in luck right know 'cause Ridgely will be closed for the season shortly before you're gonna be ready to hop on a cart again. So you'll have until March to do this homework assignment I'm about to give you.

Go to:

http://www.ushpa.aero

Click on "Members Only" and log in.

About the first thing you'll see is a little box that says "Special Links".

It has two items. Click on the top one - "Safety Briefing: Tandem AeroTow"

READ IT and do what it says.

Take particular note of the sentence that starts off:

SHOULD THE TANDEM GLIDER BECOME UNATTACHED FROM THE TUG DURING THIS MANEUVER...

and make sure you don't skim too fast through Paragraph 7.

As to your assertion that a weak link has never saved anyone at Highland, how do you know?

'Cause:
- I've never heard of anything that comes close to qualifying for that prize;
- around August I posed the question to Sunny and neither has he; and
- as much as a great many people would LOVE to stick it to me - I STILL ain't hearing SHIT.

If a weak link breaks just prior to a lockout, that is saving someone's life.

To oversimplify just a bit... A WEAK LINK DOESN'T AND CAN'T BREAK JUST PRIOR TO A LOCKOUT. Even the 0.50 to 0.75 G crap I was flying for all those years wasn't breaking before I was way, way, way into a lockout. And I could always release before it did.

You are arguing that because weak links sometime's break when the pilot is not in danger that they don't do any good when the pilot's life is in danger. That is beyond absurd.

http://groups.yahoo.com/group/skysailingtowing/message/4633
Weaklinks and aerotowing (ONLY)

Steve Kroop - 2005/02/10 04:50:59 UTC
Tow Committee Chairman - 2006

Weak links are there to protect the equipment NOT THE GLIDER PILOT. Anyone who believes otherwise is setting them selves up for disaster.

http://groups.yahoo.com/group/skysailingtowing/message/4597
RE: [Tow] Weaklinks

Donnell Hewett - 2005/02/08 23:28:31 UTC
Department of Physics
Texas A&M University-Kingsville
MSC 175 Kingsville TX 78363-8202

It is impossible to design a weaklink to release the pilot when he loses flight control because there is no correlation between towline tension and flight control.

Dr. James Freeman
Dynamic Flight
Trawalla, Victoria, Australia

2005

The purpose of a weak link is solely to prevent the tow force from increasing to a point that the glider can be stressed close to or beyond its structural limits. Lockouts can and do occur without increasing tow tension up until the point where the glider is radically diverging from the direction of tow. At this point tension rises dramatically and something will give - preferably the weak link. Given that a certified glider will take 6-10G positive a 1.5G weak link as opposed to a standard 1G weak link should not significantly increase the risk of structural failure. It will however significantly decrease the probability of an unwanted weak link break.

http://groups.yahoo.com/group/skysailingtowing/message/6671
Weaklinks

Gregg Ludwig - 2008/10/07 22:08:56 UTC
ushpa Tow Committee Chair

Tad-

I find your latest post quite interesting. I must say it has taken me sometime to get used to or accept your writing style but you make some valid points. When you refer to "ushpa" you are actually referring to me, Chair of the ushpa Tow Committee. Our next Tow Committee meeting will be at Chattanooga, TN 23-25 October. Can you attend?

http://www.chgpa.org/forums/viewtopic.php?f=2&t=2467
weak links

Danny Brotto - 2007/05/16 23:15:19 UTC

Weak links are not a secondary release system...

So, Matthew, are you starting to get the slightest clue that some of these people on similar wavelengths might actually know what they're talking about?

Janni,

So how come you didn't release? (Yeah - That's a rhetorical question.)

Danny Brotto - 2008/11/04 12:49:44 UTC

An instance where the weak link could have broken and I'm glad it didn't...

I had the Axis on the cart with the AOA a bit high, launching to the west, with a moderate 90 degree cross from the left. I came out of the cart rolled and yawed to the right with the upwind wing flying and the downwind wing stalled. It was rather dramatic. If I had released or if the weak link had broken, the downwind wing would have further stalled and I would have cartwheeled into terra firma in an unpleasant fashion. I held on tight gaining airspeed until the downwind wing began flying, got in behind the tug, and continued the flight.

Sunny later told be he was about to give me the rope and I thanked him to no end that he didn't. Lesson learned, check AOA on the cart especially in crosswinds.
---
An instance where the weak link held and it would have been nice if it had yielded...

On another instance, I was towing behind a trike being piloted by Bill Bennett as part of a demo at Fairfield (my sailplane port.) These were the early "experimental" days of aerotow. We were using a center-of-mass tow system, a three-ring circus release, and a fairly short rope. Bill commenced the tow, I came off the cart, and Bill started a rapid climb. This put me below the trike, stalled, and soon into the prop wash and tug wing-vortices. My Axis began to roll to the right, I tried to release but the polypro towline had some slack and the release mechanism held tightly. The line then tightened. I do not remember what kind of weak link was being used but with the mounting pressure I thought for sure it would break; but it didn't. I was rolling past 90 and gave the release one last yank. It released, I completed a wing over just over the tree line, and came in for a nice landing. Bill and I debriefed about the pull-up. The subsequent tow, without the rapid climb out, went okay.

Lessons learned, abandon the three-ring circus and use a decent release (I purchased the then "new-fangled" Wallaby Release) and you can't count on the weak link to get you out of an emergency situation.

Matthew Graham - 2008/11/04 18:46:05 UTC

Tad,

Just because you wrote an article on Bill Bennet's accident doesn't make you an expert on the subject. You aren't an NTSB investigator. As to Sunny not responding to your post, Sunny isn't addicted to the forum like you and I can't recall Sunny ever posting. As to your argument, it still doesn't hold water. I could argue that weak links work because they have never had a towing fatality at Highland. People use weak links to tow at Highland, there aren't any fatalities at Highland. Ergo, weak links save lives.

So yes, I have no conclusive evidence regarding the use of weak links. But neither do you.

Tad Eareckson - 2008/11/05 03:00:49 UTC

Five hours, fifty-six minutes, twenty-one seconds. High point of my year.

From hope for a rational, informed, intelligent discussion with promise for making progress back down to the usual opposite.

So Matthew,

What article are you talking about?

I didn't write an article. I didn't say I was an expert but - what the hell - compared to where you're coming from I'm a fucking genius. Meaning - of course - that I have the ability of your average ten year old to be able to predict what's gonna happen when the kite string breaks.

What post that Sunny didn't respond to are you talking about?

You could argue that weak links have saved lives but you'd have to be able to cite some evidence. Your one attempt was a rather miserable failure based upon a popular urban myth. I'm still waiting for any example with fewer than two asterisks.

On the other hand, I, in fact, HAVE witnessed and CAN document a whole lot more destruction caused by weak link breaks than you can their alleged benefits.

I know of only two potentially serious launch incidents at Ridgely (prior to Danny's post I only knew of one). Both of them could have been bad news if tension had been lost at the wrong time.

By the definition of whatever imbecile it was who wrote the HGFA rule concerning weak links - I haven't flown with one for a couple of years. There's nothing on my end of the tow line that's gonna break when I start pulling significant Gs.

Over the course of ten seasons at Ridgely I've been in dangerous situations three times that I can recall offhand (all of them my own fault and nothing more).

Chad, Sunny, and Adam were all pretty sure I was gonna get majorly creamed at the conclusion of my very first flight there on their very first day of operation. I myself was seriously considering the possibility.

While the situation was not directly attributable to a weak link break, I wouldn't have been in it had not the goddam thing popped a few seconds off the cart for absolutely no reason. People are ALWAYS safer going up than they are coming down.

My tow problems ended the moment I stopped using a weak link 'cause now I'm the one making the decisions and exercising the control. Same goes for the few other folk who've beefed up to something reasonable.

Janni,

Did Danny's post have any effect on your humble opinion? I thought I detected something of a glow when I presented that scenario to you in a discussion we had at Ridgely.

Matthew Graham - 2008/11/05 04:25:36 UTC

Tad,
You talked about the Bill Bennet accident and the said
"I wrote about this accident fifteen months ago but"
You also said you posted the question to Sunny about weak links and he never responded.
Do you ever read the stuff you write?

Tad Eareckson - 2008/11/05 10:45:12 UTC

Yeah, Matthew, with respect to Bill Bennett, I like it when you put quotation marks around something I actually said.

What I was primarily referencing was my post of 2007/08/01 11:56:37 UTC in which I dedicated twenty-five words over the course of two sentences to address a clueless reiteration of a clueless accident report.

Eleven of those words were a quotation of the clueless reiteration so only fourteen were actually mine.

Although that miniparagraph covers most of what you need to know about this crash, it does not constitute an "article".

And neither do a few other short scattered references I made to that accident around that period.

You would have done well to copy, paste, and quote what I said with respect to Sunny too 'cause - as it is - you added a "t" to a word I actually used and invented a lot of the rest. After the medication wears off a bit please go back and READ WHAT I ACTUALLY SAID.

Back to Bill/Mike...

People who use the "NTSB investigator" crap on me (you're not the first) tend not to have the capacity to understand things themselves.

If you want to make a stab at understanding this accident yourself all you gotta do is read the tug pilot's account - 583 words - and the cause should be glaringly obvious. You don't have to be a rocket scientist or NTSB investigator to see it. You just have to be able to tie a halfway competent fifth grader on a reading comprehension test.

If it's over your head and/or you don't trust my interpretation...

Run it by Sunny - as I did. He amended my understanding of the shit that hit the fan by explaining how and why that configuration would have been extremely vulnerable to wake turbulence.

And, yeah, I do read the stuff I write and on the rare occasions when someone catches me on something I deal with it.

Right now you have a bit of a backlog of issues with which to deal.

Janni Papakrivos - 2008/11/05 23:03:26 UTC

I'm not against mouth releases or whatever else you want to use. I like the solutions Tad came up with, there, I said it before, I'm saying it again. Danny's examples from an ancient past when I was still crapping into my diapers are very interesting to listen to, no doubt, but do they really still apply to tow operations in 2008/2009? I mean, high AOA in 90 degree cross winds on a glider I've never heard of sounds pretty much like you're asking for it. His second example also reads more like "we had no clue as to what we were doing" rather than anything else. Please, guys, I'm begging for contemporary case studies by someone other than Tad. I probably witnessed 50 broken weak links this summer at Highland. I didn't witness one case when the weak link should have yielded but didn't. But I did witness pilots launching in nasty conditions. And let's not forget Paul Tjaden who would have been screwed by a stronger weak link.

Tad Eareckson - 2008/11/06 00:52:13 UTC

Janni,

Thanks for weighing in again. (And Matthew, thanks for not weighing in.)

And thanks for the plugs - but the multi-string was Steve's idea.

I too would LOVE to get contemporary case studies by someone other than Tad. Two problems though - people tend not to give enough of a rat's ass to participate and dangerous AT incidents are extremely rare anyway.

I totally agree with you that both of these problems could have been taken care of well prior to the point at which things got ugly. But that's irrelevant. We only need to look at them in terms of textbook examples of what a weak link can and can't do - and both of those are contrary to the popular perception.

We have to recognize that shit CAN and, in fact, DOES happen. Damn near all the time it comes off it's clear of the ground and of no consequence whatsoever. But just damn near all the time.

Sometime a while back this season Bob Koshmaryk got dust devilled right off the cart, dragged a tip, and got into an oscillation problem. They were getting worse so he did EXACTLY what he should have and released on the way back from one. If he had released or been released or had a weak link pop at the wrong time he could have ended up being the second area ATer to get a face full of titanium within three seasons.

And you yourself were relying on luck to help keep us below a one to one ratio.

So let's say these incidents are happening at a rate of one per twenty thousand tows. That means that your individual chance of getting into a serious low level situation is about zilch. But just one Holly in a decade of towing is too goddam many - especially when a little better training and a lot better equipment would make that sort of thing a virtual impossibility.

There's no freakin' way I'd tow with a downtube mounted actuator. I would if I had to - but I don't have to. NOBODY has to.

I didn't witness one case when the weak link should have yielded but didn't.

I'd be amazed if you witnessed one case when the weak link should have yielded - PERIOD. I've never experienced nor seen one.

No, I haven't forgotten Paul Tjaden. But he has those two asterisks I was talking about earlier.

Here's his opening line regarding the incident...

The lockout Lauren mentioned was precipitated by my attempt to pull on more VG while on tow.

OK, nobody's enough of an idiot to screw with the VG before there's a bit of daylight between him and the ground.

The other asterisk is that he was using a release for which he had to reach.

(There would have been a third asterisk but, since he wasn't able to reach it in time, the fact that its performance sucked so much that it might not have functioned anyway is irrelevant.)

Now let's assume that the VG distraction had nothing to do with the severity and speed of the lockout and move him down a thousand feet.

He's dead - no matter what he's using for a weak link. Steve is who'd I put my money on in that race.

And let's not forget Paul Tjaden who would have been screwed by a stronger weak link.

NO. WRONG. INVALID.

He broke a weak link at about 1.3 Gs of tension. Let's give him a 3.0 G link. Tell me how he gets screwed?

(I've taken the liberty of fixing the grammar.)

A weak link is there to protect the equipment - not the glider pilot.

At altitude a three G weak link will leave you a completely intact glider with which to fly away.

Anyone who believes otherwise is setting himself up for disaster. The pilot actuating his release is the way to save himself.

He's talking about you, Janni. Odds are you'll never again have another launch incident like that but you're not gonna get away with two more if you keep relying on a weak link of any strength to do your job for you. Put your brake lever on your basetube - like Matthew did.

Matthew Graham - 2008/11/06 01:08:38 UTC

Tad,

Here's is what Tow Me Up says about weak links.

Weak Links - Probably the most important item in any tow system. A weak link acts like a fuse, in that it responds instantaneously to an overload condition in the tow system. There are many things that can produce extreme and unplanned loads on the tow pilot. Some of the overloads we have seen include an overzealous tow operator, line dig or jamming of the towline, vehicles and boats running over the towline and dragging it away - with the pilot still attached, pilot entering a very strong thermal on tow. Typically a weak link that breaks at 75% of your inflight load is desired. (ie. If you, your gear, and glider weigh 300 pounds; you should use a weak link with a 225 pound breaking strength). Weak links are essential to prevent overloading your glider, as they limit the maximum force that can be exerted on it to 75% over your normal inflight load. Some pilots feel towing causes severe stress or damage to their gliders. Our experience has shown that towing causes little noticeable wear, and frankly our gliders are exposed to 100% over their normal inflight load when we do a simple 60 degree banked turn. If it is unsafe for the glider to perform steep turns, you probably wouldn't want to be flying it anyway.

We are big fans of testing, and virtually all of the products on this site are tested to failure to ensure they perform as designed. We do a combination of computer modeling using a finite element analysis program to predict loads in areas of stress, and destructive testing using load cells and strain gauge testers. A weak link is useless if you don't know what strength it breaks at in a predictable manner. We use only Dacron or Polyester weaklink line specially manufactured for us to our specifications and each batch of line is tested to verify its actual breaking strength . We are big fans of sewn weak links, since they break in a very predictable manner at the rated strength of the line used to make the link. Sewn weak links are offered in a wide range of breaking strengths. These are the ultimate in ease of use since they don't require any fiddling to tie, and you know exactly what load they will break at. We also carry a wide range of Calibrated weak link line with instructions to tie them so they break in a predictable fashion at a predetermined load. We have even added a page to show you how to build your own Weaklink tester to calibrate the breaking strength of your own links for around $100 from readily available materials.

Pay particular attention to the first line-- "Weak Links - Probably the most important item in any tow system".

Your argument, as best as I can dicipher, is either--

1. Weak links aren't necessary.

or

2. If you hit the release in time, then you don't need a weak link.

So, please clarify your position. Try to avoid the mish-mash of cut and paste and non-sequiturs and comments to various people. Please, simply state your position on the matter.

Chris McKee - 2008/11/06 03:12:35 UTC

Shocker ... first time I read the forums in 6 weeks and Tad is arguing weak links. I don't think I've ever met anyone who loves to hear himself talk more than Tad ... surely no one on this forum! At least I haven't missed much ... argument looks the same. Same piss poor attitude ... See ya in another 6 weeks ...

P.S. Culinary School Rocks ... no weak links and no Tad

Tad Eareckson - 2008/11/06 08:17:47 UTC

Gee Matthew, I'da thunk the first thing you'd have wanna have done would have been to apologize for the crap you wrote earlier. You coulda regained some respect from me that way, but... Go figure.

So, still unable to provide a single instance of an AT weak link break anywhere ever that was totally desired and necessary, you copy and paste stuff from a guy who's an expert on towing paragliders from a payout winch mounted on a boat blasting up and down the Columbia River but has zilch experience with hang gliders and even less with aerotowing them (and, note, it's pretty much impossible to aerotow a paraglider).

OK, if that's the best you can do, we'll go with it.

I don't know why you pasted the second paragraph 'cause it's totally irrelevant to the discussion, but looking at the pertinent stuff...

Weak Links - Probably the most important item in any tow system.

The people who have their shit together in aerotowing understand that CONTROL is the main safety issue and that weak links have absolutely nothing to do with that equation. A weak link can only be of any use after you've flunked the test.

A weak link acts like a fuse, in that it responds instantaneously to an overload condition in the tow system.

Yeah, so? A hang glider isn't much worried about overload until it passes six Gs. With or without weak links we virtually never get into a situation in which that could become an issue.

Is there anything else we need to discuss there?

Stuart is a good guy, smart, has a great web site, and runs a smooth ship.

Here's what else he has to say (on one of my other threads)...

http://groups.yahoo.com/group/skysailingtowing/message/6742
RE: [Tow] Re: Want to buy (WTB) Weak link tester

Stuart Caruk - 2008/11/04 20:52:16 UTC

Will weaklinks prevent injuries to pilots who have crappy launch skills and get drug across the ground on launch? Will they protect against lockout, or even a vertical lockout if the pilot is dumb enough to have the line come tight going downwind? Nope and Nope. The weaklink protects the equipment to ensure the pilot has something left to fly. It's up to the pilot to decide if they are capable of flying it. Weaklinks don't make better pilots than reserves do, and frankly they are in about the same class.

I think a weak link is essential. Its sole purpose is to ensure that maximum designed tow forces are never exceeded.

Stuart Caruk - Director of Research and development
http://www.TowMeUp.com - TowMeUp@...
(360-887-0702) Voice - (360) 887-1930 Fax
23102 NE 3rd Avenue, Ridgefield, WA USA 98642

which is ONE HUNDRED PERCENT FUCKING PRECISELY what my position is.

Tad Eareckson - 2008/11/08 15:54:26 UTC

Dear Mister Moderator,

I don't know what your understanding of this issue is but I'm hoping that by this point you've noticed that there's a consistency of position amongst the less brain damaged people in the sport, the USHPA Tow Committee, the USHPA Standard Operating Procedures, the FAA, the physics folk, and what a lot of the smarter pilots are doing.

This discussion began with a new pilot raising a concern that his rate of weak link breaks were off the scale.

Danny, one of those smarter (and better) pilots I had in mind, provided very concrete evidence of one of the points I've been trying to get across for a very long time - that the use of understrength weak links is a potentially lethal (as well as wasteful) practice.

Kevin, also well into that category, also concurs that the kind of nonsense that we accept as par for the course should not be happening.

And, as you note, the discussion was fairly civilized, calm, and - I'll add - academic.

Then Matthew comes in with some bewildering ad hominem attack.

You called him on it. Thanks. It needed to be done.

But his post was basically just an annoyance. It didn't do me any harm - it just make him look like a jerk.

But where he did the real damage to this discussion was to repeatedly misquote me and misrepresent what I said. That can make ME look like a jerk to the many sloppy readers who frequent this wire.

That's a serious issue as far as I'm concerned. That's how come they have libel laws out in the real world.

I had to waste a lot of time and energy dealing with it, it significantly derailed the discussion, and he gets to skate free.

Then Chris emerges from the woodwork to join a discussion in which he is monumentally unqualified to participate and drags things down even further with a naked personal attack. Search the archives and try to find any indication of him having something positive to contribute to any discussion that requires an understanding of the equipment we use and the science behind it.

Notice he didn't/wasn't able to address or refute anything I said so he did the only thing within the normal range of his capacity - toss yet another stink bomb.

So why bother with the stupid crack of 2008/10/29 and then just let this other sludge slide?

This is where and way all of these conversations start going down the sewer and it always happens 'cause nobody 'cept me calls these folk on much of anything. What was it that Ben said about a stitch in time?

Brian Vant-Hull - 2008/11/08 22:56:24 UTC

Geez Tad;

He's a moderator, not a copy editor. NOT his job to check the accuracy of what people say, just whether they get so obviously offensive that even a casual reader will be taken aback. Chris may be in the gray area, Matt much less so. In fact, I think you were far more offensive to Matt than he was whether or not he misrepresented you. Please, give it a break.

Marc Fink - 2008/11/08 23:30:24 UTC

Chris McKee - 2008/11/06 03:12:35 UTC

Shocker ... first time I read the forums in 6 weeks and Tad is arguing weak links. I don't think I've ever met anyone who loves to hear himself talk more than Tad ... surely no one on this forum! At least I haven't missed much ... argument looks the same. Same piss poor attitude ... See ya in another 6 weeks ...

P.S. Culinary School Rocks ... no weak links and no Tad

Have you learned how to prepare weak-a-link stew? Hot and spicey, though can upset the digestion easily.

Gary Devan - 2008/11/08 23:59:19 UTC

Re:

Tad Eareckson wrote:Dear Mister Moderator . . .

as regards the basic message?
amen.

Tad Eareckson - 2008/11/09 16:42:42 UTC

Brian,

I don't know if you've taken a look at one of those little color blindness test charts lately but Chris was NOWHERE NEAR the gray layer. He was way down at the bottom of the flaming red zone - as is often the case.

With respect to Matthew... My fuse has gotten pretty short.

In a previous incarnation of this discussion he made the comment:

http://www.chgpa.org/forums/viewtopic.php?f=2&t=2467
weak links

Matthew Graham - 2007/07/23 02:14:04 UTC

Egads! Popping wink links isn't your only problem.

whilst operating under the delusion that weak link rating had something to do with hook-in weight.

You were the one who called him on it - rather too gently, I thought.

That needed to be followed up by an "Oops, sorry 'bout that." It wasn't.

His first contribution to this thread was an out of the blue personal insult. No apology - nor even explanation - there either.

Then repeated multiple misrepresentations of what I had stated despite repeated cautions and requests to actually READ the material upon which he was commenting.

That should have generated another "Oops, sorry 'bout that." but again he continues on as if he's never been capable of error of any kind and has the gall to ask "Do you ever read the stuff you write?".

That's a super strategy if one is running for political office but it has no place here.

My definition of a moderator is someone who moderates. I didn't request and would (and have) STRONGLY OBJECT(ED) to Mark editing any copy.

As I have said in previous discussions - to little effect - it helps moderation ENORMOUSLY when a third party steps in with a simple intervention like "No, Matthew, that's not what he said. Go back and read what he said." That doesn't have to be Mark - that can be any halfway literate member of the forum.

But it seldom happens, things inevitably degrade, and Mark always winds up having to spend a lot of time threatening the people on the right (me) and clueless (most everyone else) sides of the discussion with expulsion.

My take of the Matthew:Chris ratio is the precise opposite of yours. Chris can be totally ignored - he's relatively harmless. Matthew - although much less overtly malicious - mixes genuine effort and legitimate - although misguided - concerns with negligent disinformation and clouds the issue. He's way more disruptive and dangerous than Chris could ever hope to be.

Easy segue to the "casual reader"...

This discussion concerns a major safety issue. This is no place for no goddam "casual readers". Matthew's casual reading is precisely what got this thread gummed up and gave Chris an opening. I strongly recommend that casual readers stick to weekend flying recaps where they can't do much harm.

This issue of AT weak links is so difficult to understand that - worldwide - the number of hang glider pilots who totally get it would all fit in a Chevy Suburban and still have plenty of room left over for harnesses.

The reason for that is that we got it wrong from Day 1. It's wrong in the books, regs, and training and we're just lately starting to get it right on a rather microscopic level. It's taking a LOT of work though and I don't need any more potholes or speed bumps thrown in my way.

Gary,

Thanks much for your comments - on and off forum.

Brian Vant-Hull - 2008/11/10 03:03:29 UTC

Tad;

You are right, in terms of damaging what I believe is your largely correct arguments, Matthew is more dangerous than Chris. But you are asking the "moderator", a volunteer, to perform a highly involved and subtle task. However useful and beneficent it may be, it's asking way too much. Sorry to say, you're on your own until a true conflagaration breaks out. And then Mark's still not compelled to do anything unless he feels like it because he's a volunteer. Let's not make him feel unappreciated by asking too much.

Maybe you'd do better to consider Matthew a worthy opponent to help crystallize your statements for everyone else? I believe Johnson used this approach to push through civil rights. He won over a reluctant congress.

I'm not ready to say you are completely correct until I've gone through the math of lockouts for myself. Then there may be other extreme things like the pilot flying way too high while the tug's release jams so the tug tries to break it by gunning the throttle, etc. The blanket statement that weak links do nothing to protect the pilot may not be strictly correct, just mostly true.

Brian Vant-Hull - 2008/11/10 13:03:30 UTC

After some thought and prodding by an anonymous source I want to lay things out as clearly as I can.

1. We definitely want links that will break when there's a sudden snap in tension caused by such non-normal flight scenarios such as the cart getting hung up in a pothole, the tug taking up without taking up slack in the line, or a wing falling off the tug causing it to plummet like a dead weight. In these cases the weak link protects both the pilot and equipment.

2. We would prefer the weak link not break during normal tow forces on a thermally day. This could be dangerous.

3. Tad claims that lockout forces are no larger than normal thermally day tow forces. He claims therefore that the accumulated risk of unneeded weak link breaks during tows outweigh the accumulated risk of the more rare breaks during lockout. He wants to increase the average weak link strength that most heavier pilots use to match that typically used by lighter pilots.

All extraneous statements Tad has made about weak links largely being useless I'll ignore as coming from a mind under duress that hasn't taken the time to qualify blanket statements.

I'm willing to accept his claim that lockout forces are not larger than normal tow forces (but would prefer to verify it myself and this will take time to get around to).

The claim that the accumulated risk of breaks during normal tows are greater than that during lockout is much more subjective, and that's where the argument lies. Is this a fair assessment?

Gary Devan - 2008/11/10 14:06:01 UTC

Brian Vant-Hull wrote:Tad;
. . .asking the "moderator", a volunteer, to perform a highly involved and subtle task. . . it's asking way too much.

agreed. the basic issue is not about the moderator. it's about diversions - which i'll hereafter stop being a part of. all alcoholic/addictive types are doomed if they can't resist that first drink. enablers have their own demons.

Brian Vant-Hull - 2008/11/10 14:11:59 UTC

last emendation: where ever I say lockout, I should add 'or other pilot induced in-flight scenarios'.

Tad Eareckson - 2008/11/10 14:51:50 UTC

The writing is getting ahead of me. I'm gonna go ahead and post this which I had ready for Brian's of 03:03:29 and then try to catch up on the rest.

Brian,

I greatly appreciate what Mark has done to keep this wire running. I'm just suggesting that he actually might be able to do less of it by stepping in with a short word before an all out flame war erupts.

But - again - ANYBODY (with half a brain or better) can be an effective volunteer moderator.

Gary thinks I'm a total freakin' asshole. But he also thinks that even a total freakin' asshole deserves to be treated fairly. I'm totally with him on those points. (Even Chris occasionally posts something worth responding to and I recently credited him with being right for a change.)

Six words from a neutral third party just made all the difference in the world. It lets me know that I'm not dealing with a total lunatic asylum and it gives a hint to the aforementioned goddam casual readers that maybe I'm not as totally deranged as is the popular perception.

No way Matthew gets worthy opponent status on anything remotely like the tack he's been on since 2007/07/23.

Yet another example... When anyone with a reasonable understanding of aerotowing reads the trike pilot's account of the Bennett / Del Signore fatalities it's freakin' blindingly obvious case closed.

Assuming there was something wrong with my assessment a worthy opponent would have read the source material and started punching holes. "OK, so how does that explain this?" Instead I get the vintage Marc sort of response along the lines of "You don't have five thousand hours in tugs and gliders each so you can't possibly be intelligent enough to comment."

There are some people out there who would make worthy opponents but - unfortunately - damn near all of them are already sitting in the Suburban. (I'm actually currently working on one who - I believe - is real close to putting the other foot inside and buckling up.)

You yourself are certainly worthy opponent material. On that note - back to the discussion.

You're making this too complicated.

Let's look at one of Matthew's statements again...

If you ever decide to stop using weak links altogether, let me know so I can buy a life insurance policy in your name.

and do a substitution:

If you ever decide to stop flying with a parachute, let me know so I can buy a life insurance policy in your name.

I wouldn't feel particularly safe eliminating either one but, statistically, the odds of Matthew making - rather than losing - anything on the deal are, for all intents and purposes, ZERO.

Now lemme save you a bunch of way-over-my-head math real life data.

On 2005/09/10 behind Sunny at 2400' with the Garmin 76S logging coordinates I got hammered, was rolled rapidly and severely to the right, and lost thirty feet before I was able to work on the problem of getting the bubble back.

I was using what some people are starting to realize was a dangerously understrength weak link - 0.76 Gs. IT DIDN'T BREAK. I released.

Move that scenario down to just off the runway and assume that my adrenalin doesn't kick in any faster and I'm dead. And if I'm dead anyone lighter than me - which is just about everyone - is really dead. And Karen is really really really dead.

Steve Kroop again...

Weak links are there to protect the equipment not the glider pilot.

If you persist in using the word "lockout" in a discussion about weak links you're gonna have a hard time understanding them.

On an earlier occasion the same 0.76 G weak link held while I rolled about thirty degrees beyond the placard limitation of my glider. So you can't use the terms "weak link" and "control" in the same sentence either.

The jammed tug release scenario...

A weak link isn't there to allow you to fly with crappy equipment. If you fly with a crappy basetube the weak link isn't going to save you. The same must be assumed with respect to the release.

2000/08/26 - Ralph, at waveoff, can't get the Lookout release he borrowed from you to function. Same flimsy weak link. He STALLED OUT THE DRAGONFLY. Sunny GUNNED THE ENGINE. "This resulted in a SUDDEN AND SEVERE PULL ON THE HARNESS AND GLIDER; I was only able to pull on the release again, WHILE SIMULTANEOUSLY PRAYING FOR THE WEAK LINK TO BREAK."

THE WEAK LINK DIDN'T BREAK!

If you start trying to dumb down the weak link to do a job which it can't do anyway YOU'RE GONNA KILL DANNY.

The purpose of a weak link is solely to prevent the tow force from increasing to a point that the glider can be stressed close to or beyond its structural limits.

Brian Vant-Hull - 2008/11/10 15:27:42 UTC

Based on these situations, the only thing that's causing all these normal flight time weaklinks to break is them getting frayed. I don't believe this because I once broke 5 weak links in a row while trying to learn to tow a K2. One of those may have saved me from a lockout situation, but I'm not sure if in that case I released first or not. I think I did release in that case instead of it breaking. In other tows I felt a bit out of control but not panic stricken enough to release.

Since in 4 out of 5 tows I felt somewhat under control but the link broke, and when I (and Ralph) were out of control it didn't, it seems to back up your argument that weak links don't prevent in-flight incidents. But I don't know if the tug pilot had a very different feeling and was being yanked around by my poor tow technique on that glider.

Tad Eareckson - 2008/11/10 16:13:55 UTC

Brian,

The worthy opponent of my dreams. Ahhh...

The cart getting hung up in a pothole. NO. That has to be the release.

http://ozreport.com/pub/fingerlakesaccident.shtml



The weak link DOES NOT KEEP THE PILOT FROM GETTING HURT. He's undoubtedly got an understrength weak link but he gets hurt. The weak link only fails AFTER he gets hurt. You could make a weak argument that in the absence of any weak link he's gonna get dragged AFTER he gets hurt but - why bother? There's no freakin' way a 2.0 G weak link is gonna withstand a super power whack like that.

That release configuration, by the way, was no freakin' way in compliance with the SOPs.

The tug taking up slack in the line. Not really. With the glider pointing at the tug any increase in tension isn't gonna last very long. Not much of an issue.

Wing falling off the tug. If you want. I'm probably gonna be able to release 'cause the tug's 250 feet away and that gives me some time.

Point 2. Yeah. We don't want the weak link to break on a thermally day 'cause that's the only sort of day on which we want to be flying. We want to be the ones making that decision and we can virtually always do it faster and better than the weak link. And a weak link that fails in such a manner as to inconvenience everybody at the flight park can also fail in such a manner as to kill you.

Point 3. Yeah, pretty solid. We are not seeing evidence of lighter pilots being injured at a higher rate than heavier ones. We are - in fact - seeing quite the opposite.

Mind under duress... Yeah, totally solid there.

Weak links useless, blanket statements, qualification...

WE DO NEED TO FLY WITH WEAK LINKS - BUT...

In the entire history of Ridgely flight ops there would have been no negative consequences if we hadn't.

Just as if - for non aerobatic flights - there would have been no negative consequences to anyone flying without a parachute.

There is a point at which a light weight weak link becomes DANGEROUS. That point has been defined by the FAA and other folk who tend to have their shit together as 0.8 Gs.

We have been flying weak links which are - in effect - as low as 0.4 Gs, i.e., HALF OF WHAT THEY SHOULD BE and there is absolutely no question that they ARE making things more dangerous.

We should be not be hugging that lower limit and we have no need to push the upper. Karen is in the right ballpark at 1.22 and has no problems. If she flies in the middle of the safety range - at 1.40 - I predict she will have even less than no problems.

I'm willing to accept his claim that lockout forces are not larger than normal tow forces (but would prefer to verify it myself and this will take time to get around to).

Again. Skip the math. Just look at the flight reports. When are we having weak link breaks and when aren't we? I'll save you the trouble. We're having them when we don't want them and not having them when we do.

The claim that the accumulated risk of breaks during normal tows are greater than that during lockout is much more subjective, and that's where the argument lies. Is this a fair assessment?

No. This is not subjective. We have TONS of data. I'm still looking of JUST ONE positive weak link break with no asterisks. I'm having much better luck with my Sasquatch hunt.

Oops, yet another post on which to catch up.

I'm not sure where the getting frayed thing came from but, to some extent, yeah. But not necessarily 'cause they're being used for multiple flights. Virgin weak links often break right off of the cart. Safe working load thing.

http://ozreport.com/forum/viewtopic.php?t=13573
weak links

If a weak link breaks and saves you from a lockout situation it's dumb luck. It can never be counted on to break until you're well into a lockout situation. And if you happen to be low at the time things are already potentially lethal.

If the tug pilot doesn't like what's going on at the back end of the string he never has to wait for the weak link to kick in - and, at launch, can't afford to.

P.S. I don't think you CAN learn to tow a K2.

Brian Vant-Hull - 2008/11/10 16:54:20 UTC

Sorry Matthew, I can't stop. I'm addicted.

Tad, won't your variable strength weak links be stronger than the tug's for heavy pilots? This means the pilot will end up with the rope, which is way too annoying. Would you say the tug is using under strength weak links too?

Good research on finding a case where the cart hits a hole and the glider gets dragged off before the link breaks. Not sure I want one stronger than this, though. Even if it broke a little late, I wouldn't want it breaking even later.

Matthew Graham - 2008/11/10 18:08:52 UTC

Tad,

You answered the question yourself.

See-- http://ozreport.com/pub/fingerlakesaccident.shtml

The weaklink broke when the cart got stuck and the pilot was not pulled along the ground-- minor injury to pilot.

And again using your made up numbers-- 40,000 safe tows at Ridgely. Weaklinks are used at Ridgley-- 40,000 safe tows using weak links.

I again ask, do you ever read the stuff you write? (This is a rhetorical question-- no need for a three page response.)

And for the record, I did agree with you when this thread came up previously that weak links are not one size fits all-- different strentgh weak links for different wing loadings. However, your contention that weak links are dangerous is ungrounded-- again note the 40,000 safe tows at Ridgley with weak links. Also, there's a stronger weak link at the tug end of the line. If a pilot doesn't use a weak link then there is still the weak link on the tug side of the line. Are you suggesting that this weak link is also pointless?

So, please, just answer this simple question. Do you contend that weak links should be eliminated from Hang Gliding towing operations? Try using the word "yes" or the word "no".

Tad Eareckson - 2008/11/10 19:05:14 UTC

Brian,

The weak link with which I've been flying blows at about 500 pounds of tow line tension. Yeah, that's about a hundred pounds after the one at the tug end blows, so yeah, I'd get the rope.

That would be definitely be way too annoying - IF - it were ever going to happen. But it's never going to happen.

I am totally confident that I can get myself off the line LONG before my tow line tension gets to over triple ambient.

YOU'RE STILL THINKING OF A 1.4 G WEAK LINK BREAK AS SOMETHING THAT'S GOING TO HAPPEN. Start thinking of it as something that will NEVER happen. I can sympathize - It took me quite some time to get out of the old mind set.

It's exactly like a parachute deployment. If it happens it's gonna be a real pain in the ass. But it never happens.

My original scheme was to dial my weak link strength to just under the tug's. Then I said "Waidaminute. I'm not having some other pilot's decision dictate what I'm gonna do on my end of the line."

Here's what the FAA says on the matter...

FAR Part 91.309

(i) A safety link is installed at the point of attachment of the towline to the glider with a breaking strength not less than 80 percent of the maximum certificated operating weight of the glider and not greater than twice this operating weight.

(ii) A safety link is installed at the point of attachment of the towline to the towing aircraft with a breaking strength greater, but not more than 25 percent greater, than that of the safety link at the towed glider end of the towline and not greater than twice the maximum certificated operating weight of the glider.

(Note that the regulation cannot be complied with if the glider maxes out his weak link.)

Yeah, the tugs are also using understrength weak links. USHPA specifies a 2.0 G weak link limit for the glider. That means that if Karen maxed out her weak link it would blow at about the same time as the one up front.

Paul was flying one of my 1.4 G weak links when the shit hit the fan. The Dragonfly's weak link blew about twenty pounds sooner and he got the rope. That wasn't my fault. That was the tug's fault.

I note also that Carlos had a loop of Greenspot on the end of his two point bridle, locked out, had a release failure, and got the rope. That was also the tug's fault.

The Finger Lakes accident...

Just to get our terms straight... That glider tucked off the cart.

Again - That was an low strength weak link - 243 pounds tow line tension max, low end of the G range.

You have to understand that - within the range of maybe as low as 0.5 up to 2.0 Gs - the weak link strength/rating had ABSOLUTELY ZERO bearing on any aspect of that "tow".

The weak link is there to protect the glider - not the pilot. It couldn't protect the glider 'cause it was too low (as would have been the case of a lockout shortly off the cart). Since the weak link couldn't protect the glider the glider was of no use in protecting the pilot.

Once the nose had touched the ground the relevant part of the show was over.

Matthew,

I'll get to yours ASAP.

Tad Eareckson - 2008/11/10 20:15:36 UTC

Matthew,

Thirteen stitches in the lip is only a minor injury when it happens to someone else.

Getting dragged a ways across a nice lawn is not what was gonna get him injured. The sudden stop was what got him injured. And there was no possibility of him getting dragged after the sudden stop.

You do not prevent an accident like that by dumbing your weak link down from 1.22 to 0.60 Gs. You prevent it by using a:
- cart; and
- release
which comply with the USHPA SOPs.

Forget the cart. Rewind the tape. Move the brake lever down to the basetube where you have a couple of fingers on it at all times. What happens?

Forty thousand is the low estimate I got from Sunny earlier this season. I have seen but a tiny fraction of them.

One of that tiny fraction involved Denis Scheele hopping on a shiny new Talon for a demo hop. As he was coming off the cart the weak link failed for the usual no reason. He folded a shiny new downtube.

By my definition that was not a safe tow.

Cragin reported having one pop low, getting a wind shift, and having to land downwind. He got a burned knee out of the deal.

Danny and Bob Koshmaryk have both been in low oscillation situations in which an ill timed weak link break could have been catastrophic. Neither of those launches had any physical consequences but when one is literally hanging on by a thread the flight cannot be considered safe - just lucky.

Both Victor and I have folded downtubes which would have remained intact had we been using adequate weak links.

Now how 'bout you (or anyone else) giving me a Ridgely flight in which a weak link break had a POSITIVE effect.

With respect to the front end...

Jim was landing to the east when a taxiing single engine illegally turned off the runway underneath his path and caught the carabiner with the prop.

Yeah, you need a weak link at the front end. The problem is that the placement of the Dragonflies' weak links allows for the possibility of a bridle wrap following a pop. So they're not protected in accordance with the Skyting Criteria and USHPA SOPs.

With respect to your last paragraph... Please go back to the middle of the post I submitted prior to your posing it and tell me what it says in BIG BLACK CAPITAL LETTERS.

Brian Vant-Hull - 2008/11/10 20:54:09 UTC

Tad;
I've got to clear up something I don't understand in your thinking:

And let's not forget Paul Tjaden who would have been screwed by a stronger weak link.

NO. WRONG. INVALID.

He broke a weak link at about 1.3 Gs of tension. Let's give him a 3.0 G link. Tell me how he gets screwed?

Paul was flying one of my 1.4 G weak links when the shit hit the fan. The Dragonfly's weak link blew about twenty pounds sooner and he got the rope. That wasn't my fault. That was the tug's fault.

I note also that Carlos had a loop of Greenspot on the end of his two point bridle, locked out, had a release failure, and got the rope. That was also the tug's fault.

What do you mean it was the tug's fault? The tug pilot should have released? The weak link at the tug end should have been stronger? (not good for Carlos!) I don't know anything about being a tug pilot, but isn't it asking a lot to keep two aircraft under split second surveillance at all times?

I also wish you wouldn't refer to incidents described in whole different unspecified threads at unspecified times. Grows wearisome. I have no idea what the Carlos incident is. We're not all obsessing over this stuff the way you are.

Tad Eareckson - 2008/11/10 21:56:49 UTC

Yeah, the tugs are not geared to let us use anything much better than the one size fits all crap. Paul and I should be able to fly at 1.4 (or - if you really wanna push the issue - 2.0) without having to worry about getting the rope.

I think if you know anything about being a towed pilot you know enough about being the tow pilot for the purposes of this discussion.

No - I don't think it's asking to much for both or either pilot(s) to keep those planes under split second surveillance at all times. It's absolutely mandatory until you get a little air under you. But a few seconds away from the runway you can afford to dope off a little 'cause there's not much that can go seriously wrong after that.

That's how come I have no problem with Paul playing with his VG under those circumstances. Things got way out of control instantly but - what the hell - he was weak link protected and high enough for the thing to function as it's supposed to.

With respect to Carlos...

That reference was self contained. My point was that if the tug isn't operating enough in accordance with the SOPs even to prevent a glider using a weak link which limits the tow line tension to 243 pounds, you're not gonna get any less rope than Paul did.

The Carlos incident occurred 2008/06/02 at the ECC and I reported on it 2008/07/29 in the Zapata thread after Paul's lockout.

If it's wearisome - hell, skip it. But I have the data to support what I'm saying.

Matthew Graham - 2008/11/10 22:23:46 UTC

Tad,

You inablility to answer a question with a simple answer is astounding. And, yes, that is a dig.

So, you agree that weak links are necessary. And there is agreement that there should be different wink links for different wing loadings.

No one is being taught to rely on weak links. We all have a release and a back-up release. I have two back up releases. SOP is to release before a lockout or a variety of out of whack on-tow situations. If the primary release fails, go for the secondary. I was taught to go for my hook knife if the secondary fails.

And as you noted, Highland has 40,000 (your number) successful and safe tows.

So, what is the problem???

And, please, try to answer this in one succinct paragraph-- no cutting and pasting and reference to previous posts.

Tad Eareckson - 2008/11/11 00:01:31 UTC

Matthew,

Nah, I just don't like repeating things I have just made very clear in big black letters for the benefit of folk who can't be bothered to read them the first time.

No, wing loading has nothing to do with it. We're talking glider weight. And by glider weight I mean everything on the cart. But I think that's what you had in mind anyway.

In any case - there is ENORMOUS, GLOBAL, RABID, IDIOTIC resistance to the concept that Karen and Bob Buchanan should be using different strength weak links.

I don't know what people are being taught with respect to reliance on weak links. But I know what they're thinking. They're pretty much all thinking of weak links as lockout protection and that upping strength makes towing more dangerous. And that includes a lot of people WAY up on the pecking order. And people are just about all wrong.

And, in fact, people ARE relying on weak links as lockout protection 'cause most of them have release actuators up where they can't get to them in a real emergency. And most of what's left over have actuators configured such that they can't maintain control of the glider while they're going for them.

As I've said before - anybody who uses a BACKUP release is asking for BIG trouble. There is ZERO excuse for going up with a release that has any more chance of failure than one of one's cross spars.

We have SECONDARY releases ONLY to deal with primary bridle wraps which are not big deals. (But yeah, I know people are taught that those secondaries are backups - (same way they're taught that 0.5 G weak links are 1.0s)).

If the primary release fails and you have the altitude - roll away and break the weak link. If you release out of sequence with a fore trim point on the keel and your bridle wraps you can break the glider instantly.

Hook knives have no place in the discussion. Don't use secondaries that can fail. In other words - don't use curved pin Baileys.

Forty thousand - AGAIN - is SUNNY'S LOW ESTIMATE. It is not my number.

If the tow ends with a weak link break IT WAS NOT SUCCESSFUL. It was out of control. It did not accomplish the goals of the participants.

And if a weak link breaks below an altitude which permits a normal landing in the field of choice it is not particularly safe tow either.

So far neither you nor anybody else has been able to cite a single instance of a weak link break enhancing the safety of a Ridgely tow. I'm guessing the weak link break rate is around five or ten percent - probably the latter. Humor me and call it FOUR THOUSAND unsuccessful and occasionally dangerous tows. It should be ZERO.

THAT'S THE PROBLEM.

So what I'm trying to do here - primarily - is bring the USHPA to conformity with the FAA and have it codify a minimal safe weak link rating of 0.8 Gs. Personally, I think anything under 1.0 is nuts for hang gliders but I'll take what I can get.

When people start using their brains and realize that the sort of weak link breaks which Kirk described in the long distant opening post of this thread are not just expensive and wasteful but are, in fact, making towing more dangerous - occasionally critically so - this task will become easier.

When I'm talking to Brian I tend to become delusionally optimistic. When I'm talking to you I come crashing back to reality and get even more depressed than usual. How 'bout making my day and acknowledging that we have a problem.

Matthew Graham - 2008/11/11 00:26:50 UTC

Tad,
No one is arguing with you regarding different strength weak links for different loads.
Where do you get the idea that people are taught to turn and break the weak link if their primary release fails?
As to secondary releases, things fail. NOTHING IS FOOLPROOF! If your primary release fails, you use your secondary as a back-up.
If a weak link breaks unexpectedly, yes, it's annoying. But so are other things.
Some things are very annoying.

Brian Vant-Hull - 2008/11/11 00:53:46 UTC

Tad wrote:

So far neither you nor anybody else has been able to cite a single instance of a weak link break enhancing the safety of a Ridgely tow.

Earlier Janni had written:

A weak link certainly saved my butt on one occasion. I came off the cart crooked in my Litespeed, over-controlled and would have quickly been in a close-to-ground neck-breaking lockout if the weak link hadn't snapped right away. They can't be weak enough in my humble opinion, especially if you fly sluggish top performers.

To which you responded:

So how come you didn't release? (Yeah - That's a rhetorical question.)

I'd call that a brush off. Maybe people themselves fail, or things happen faster than they react, and the weak link may jump in there and save the situation. It improved safety.

Anyway, please stop saying they don't improve safety. Maybe (perhaps surely) we have them too weak and they are hurting safety, but making them too strong will hurt safety too. Maybe the sweet spot is the 1.4 g you like to quote.

If you'd leave it at that and stop saying stuff like

In the entire history of Ridgely flight ops there would have been no negative consequences if we hadn't [used weak links at all].

We could perhaps end this discussion right now.

Tad Eareckson - 2008/11/11 04:27:11 UTC

Matthew,

No one is arguing with me here and now about using weak links proportional to glider weight. But spend a little time at the flight line at Ridgely and see what's going on. It's a lot more dangerous to take the one-size-fits-all stand on this wire than it was a year and a half ago but you can count the local pilots who've beefed up on one hand.

I never said people are taught to break the weak link if their primary release fails. I'm saying they should be. What they are being taught is dangerous.

But that crap is moot anyway 'cause there's no more excuse for anyone to be going up with a with a release capable of failure than there is to fly with a side wire of similar integrity.

Yeah, my releases are, in fact foolproof. There's no way you or anyone else can get them to fail or propose a scenario in which they will. I still have that thousand bucks to give substance to the claim.

If a weak link breaks unexpectedly, yes, it's annoying.

Apparently you either didn't bother to read Danny's post or it completely failed to register.

Brian,

End this discussion right now? I was just getting my second wind.

Janni knows exactly what I'm talking about.

What Matthew, you, and I have in common is an understanding of the importance of being able to be in full control of the glider at all times. And we all use releases that comply with USHPA SOP 12-02.10:B:6 and allow us to maintain that control.

Janni has a dangerous, noncompliant piece of crap.

He also has a weak link so understrength that it would be illegal if the FAA were running this show.

So HE GOT LUCKY and two wrongs made a right. He was not in control of that situation. He just had the dice stop rolling at the right time.

The weak link that saved his butt in that situation is the same one that's gonna break his freakin' neck in Danny's or Bob's.

Maybe people themselves fail, or things happen faster than they react, and the weak link may jump in there and save the situation.

If shit happens down low where it matters, the pilot MUST be able to react faster than the weak link. Note Janni didn't say he didn't have TIME to release. He just didn't have the ability to control the situation with one hand on the bar.

When I get on a cart I'm the one in control of the situation. I don't let no fucking piece of string pick, choose, and dictate what's gonna happen next. If I want to stay on - I stay on. If I want off - I get off - at the precise time it's best for ME.

To get off if I'm flying two point I twist my left hand. If I'm flying one I relax my bite.

But I digress...

Right now my goal is to put a 0.8 G floor on the relevant USHPA requirement. Is there anybody out there still stupid enough to object to that?

Tad Eareckson - 2008/11/11 04:30:35 UTC

Oops - correction.

While the three of us all have acceptable control of our releases you two are still doing the random number generator thing with respect to your weak links.

Tad Eareckson - 2008/11/11 11:03:48 UTC

A few more insomnia induced comments on Janni's Lucky Break...

Janni's flying the supership of Two Thousand A Couple Years Ago.

I'm flying the supership of 1989.

A couple of things happened in the time between.

They made the performance AND the handling a lot better. That used to be oxymoronic.

Nowadays I pretty much always launch with the VG on. And on the HPAT that - by definition - means FULL on.

So I'm guessing NOBODY has anything to tell me about sluggish gliders.

Janni and I hook up at almost EXACTLY the same weights and tow two point and for all but the past two seasons I used the same Magical One Size Fits Karen, Janni, and Me Weak Link. So that makes me a freakin' expert on the range of situations in which that identically loaded alleged 0.76 G weak link will or won't pop.

It'll pop straight, level, centered, and smooth just off the cart and it'll hold long into your worst nightmare of an aerobatic altitude killing lockout.

I came off the cart crooked in my Litespeed, over-controlled and would have quickly been in a close-to-ground neck-breaking lockout if the weak link hadn't snapped right away. They can't be weak enough in my humble opinion, especially if you fly sluggish top performers.

His second problem WAS NOT that the glider was too sluggish - His second problem was that his glider WASN'T SLUGGISH ENOUGH for the input he was giving it.

The weak link blew WELL before the glider had a chance to start locking out. I repeat - dumb luck.

They can't be weak enough in my humble opinion, especially if you fly sluggish top performers.

So how come we NEVER hear really small pilots towing really hot gliders one point saying "WHOA! DUDE! This 130 pound Greenspot is WAY too strong! Somebody find me a tea bag."

And how come the FAA says "0.8 G minimum or you don't fly."? Don't they just keep getting safer as they keep getting weaker? And why, in the name of All That Is Holy, would the FAA and USHPA define 2.0 as being acceptable?

Matthew Graham - 2008/11/11 15:17:47 UTC

Tad,

You seem to be inventing problems so that you can come up with solutions. And you also seem far more interested in dismissing anything that anyone says that contradicts you and in looking for a worthy opponent. Actions speak louder than words. So if you want to do something actually useful, then focus your efforts on selling your straight pin bailey's to dealers and flight parks, getting USHPA and the flight parks to adopt the use 3 (?)) differrent strength weak links for different loads and promoting the placement of releases within easy reach-- promoting doesn't equate to insulting those who use a release that you don't like. And stop saying your release is foolproff. NOTHING IS FOOLPROOF!

Also, I have a big deadline to deal with today and lots of work at the office the next couple of days. So if I don't respond to you for a few days, don't go accusing me of painting. I hate painting.

Tad Eareckson - 2008/11/11 18:44:37 UTC

The problems exist, Matthew. The problem with the problems is that they've become so much a part of the landscape that the rabble assumes they're necessary and inevitable components of aerotowing.

http://ozreport.com/9.033
Why weaklinks?

http://groups.yahoo.com/group/skysailingtowing/message/6744
Weaklinks

Donnell Hewett - 2008/11/05 21:22:29 UTC

I am sorry I have not been able to participate in the discussion on weak links that has been raging during the last few weeks, but I have been too busy to even read the postings much lest respond to them until now. Let me begin by saying that I personally appreciate Tad Eareckson's efforts to improve the SOP of aerotowing as well as his suggestion to update the Skyting Criteria. It is through efforts like his that progress is made toward safer towing.

Rather than address his and other's comments made during the recent discussion on weak links, let me remind folks that the Skyting Criteria were not developed as a model of a practical towing system. They were proposed for the purpose of defining what an ideal towing system should be in order that towing would be as safe as free flight. The first four criteria are intended to make towing accurately simulate free flight, the next four are to guarantee a safe transition to and from tow, and the last four are to identify some of the safety requirements of practical implementation.

One should remember that no towing system meets all twelve criteria all of the time. Therefore, the purpose of the Skyting Criteria is to help identify when a particular system is deviating from the ideal so that one knows when to be extra cautious and when to make compensations for those deviations.

For example, in the case of aerotowing the second criterion is accomplished by speed control rather than normal tension regulation. As long as the tug and the glider are flying at the same speed the tension remains constant. In general, this speed regulation works great as long as the air is smooth and the two pilots properly cooperate. But anything that causes a differential speed between the two craft will cause the tension to fluctuate, sometimes quite rapidly. Fortunately, the fluctuations are usually quite temporary and rarely reach the excessive values encountered in other forms of towing (such as when a payout winch jams or runs out of line). Nevertheless, compensation must be made for aerotowing's inability to meet criterion two under typical aerotowing conditions. Making the towline longer or more elastic only exasperates the differential velocities, and making it shorter increases the violation of criterion one. So the only practical solution is to recognize that the violation exists and learn to live with it. (I.e. gain sufficient practical experience under a qualified instructor to handle typical thermal conditions and to know instinctively when to release from tow as soon as the situation warrants.)

Now regarding weak links, the whole purpose of a weak link is to release the pilot from tow when he cannot do so himself and the towline tension continues to rise above the limit of safe towing. What that limit is, depends upon many factors, including pilot skill and experience as well as the type of towing and the system being used. I believe everyone recognizes that "one size weak link simply does not fit all".

For example, in the case of an ideal towing system, where the horizontal tension remains constant, a weak link of 0.5 gee will allow the glider to climb at a 30 degree angle, a 1-gee weak link will allow a 45 degree climb angle, and a 2-gee weak link will allow a 60 degree climb angle. These are also the angles a pilot will find himself flying in free-flight when the weak link breaks. Personally, I am not convinced that all hang glider pilots are qualified to recover safely from such extreme aerobatic attitudes. That is why I still recommend a 1-gee maximum weak link when towing horizontally with a good tension controlled system.

However, in the case of aerotowing, where the towline tension may vary as much as +/- 0.25 gee (or even +/- 0.5 gee) when taking off on rough or grassy terrain or when entering and leaving a strong thermal, a 1-gee weak link is going to be breaking much more often than it would on a well-regulated tension system. For most forms of towing, excessive weak link breaks usually constitute nothing more than a minor inconvenience (or a major nuisance). They simply are not a safety issue at all.

However, aerotowing also tends to violate Skyting Criteria twelve (a suitable environment) by frequently towing over terrain that is completely unsuitable for landing. In this case, a weak link break is considerably more than a minor inconvenience. It potentially places the pilot in an extremely dangerous and possibly fatal situation.

Yes, the general rule of towing is, "Get off line at the first sign of danger." However, there are exceptions to this general rule. In fact, I am sure you can imagine more than one situation where getting off line is the worst possible alternative you can take. In such cases, the towline becomes a "lifeline" rather than a "death-line." It pulls you out of danger rather than plunging you deeper into danger. Releasing low over unsuitable terrain is an obvious example of this exception.

Once again, the recognition that aerotowing frequently violates one of the Skyting Criteria requires an appropriate compensation in order to be as safe as possible. In this case, one must use a weak link that simply will not break under reasonable flight conditions and typical flight situations. When one also considers the typical tension variation encountered when aerotowing hang gliders, the conclusion is that the aerotowing weak link should be designed to break in the neighborhood of 1.5 gee (or at least somewhere within the 0.8-gee and 2-gee range specified by the FAA for towing sailplanes).

One also concludes that an aerotow pilot flying with such a weak link should have the skills to recover safely from aerobatic maneuvers greater than 45 degrees - because that is what he may well encounter when the weak link does break.

I believe that the first of these two conclusions is perfectly consistent with the point that Tad has been trying to make. And I thank him for keeping this issue before the hang gliding community.

Donnell

Lionel D. Hewett, Interim Chair
Department of Physics
Texas A&M University-Kingsville
MSC 175 Kingsville, TX 78363-8202

Janni Papakrivos - 2008/11/11 19:47:49 UTC

Tad Eareckson - 2008/11/11 04:27:11 UTC

Janni has a dangerous, noncompliant piece of crap.
He also has a weak link so understrength that it would be illegal if the FAA were running this show.
The weak link that saved his butt in that situation is the same one that's gonna break his freakin' neck in Danny's or Bob's.

No it won't, because it's so wonderfully understrength. I jerk the base tube and it snaps, I totally dig it! See, being the fat bastard that I am I actually do use a tea bag for a weak link. I know that if I don't use smooth technique and reasonable conditions it will pop. I can't reiterate enough how much I love my tea bag weak link. I feel very Very VERY safe.

Note Janni didn't say he didn't have TIME to release. He just didn't have the ability to control the situation with one hand on the bar.

My bad. Here is saying it for you Tad. I didn't have time to release. I probably wouldn't have released even had I had your mouth release or whatever you use right now. Because I thought I was in control until it broke, which all happened in a fraction of a second, too quick for my level of experience anyway. My tea bag weak link saved my life that day, and I am very Very VERY grateful for that. I will never fly with anything else.

David Bodner - 2008/11/11 20:18:07 UTC

I'm a complete idiot. I haven't towed in over two years, so I know less, and have less experience, than anyone else in this conversation. But, I wade in nonetheless.

I think most will now agree that the weak link should be scaled to pilot/glider mass and, possibly, skill. But, it seems to me that the difference between an intended weak link break and an unintended weak link break is often bank angle. So, do we need a weak link that varies its strength with bank angle? The more the wings are banked, the weaker the link. I have no idea how to do that.

I somewhat jokingly imagine an iPhone on my basetube sending signals from its accelerometer via bluetooth to the weak link. I know, far too Rube Goldbergian.

Janni Papakrivos - 2008/11/11 21:02:00 UTC

I'd like to add if my weak link happens to break for no reason I land, get back on the cart and tow again. BFD!

Brian Vant-Hull - 2008/11/11 21:55:59 UTC

Well....

if it just happens to break when you are partially in a low to the ground wingover, it kinda sucks. As Tad says, the tug's pulling you away from the ground, so in many cases you're better off staying with it until you choose your moment to release. They tend to break when stuff is already bad, not before it gets bad.

Or if you're right over a tree line, etc.

Cragin Shelton - 2008/11/11 22:00:54 UTC

Janni Papakrivos wrote:I'd like to add if my weak link happens to break for no reason I land, get back on the cart and tow again. BFD!

And that, ladies and gentlemen, is what started this entire soap opera of a thread! Tad was whining that broken-link pilots at RIdgely get a preferential push to the front of the line to re-launch, delaying his turn to get into the sky.

He wanted them to use stronger weak links, not for purposes of safety, but so they would get the heck out of his way so he can fly when the sky is good.

WE HAVE GONE FULL CIRCLE!

Janni Papakrivos - 2008/11/11 22:43:39 UTC

if it just happens to break when you are partially in a low to the ground wingover, it kinda sucks. As Tad says, the tug's pulling you away from the ground, so in many cases you're better off staying with it until you choose your moment to release.

Now that just makes no sense to me whatsoever. If you're in a low to the ground wingover with the tug accelerating you you're screwed no matter what (and probably chose to launch in a 90 degree 20 mph peak of the day cross wind). The tug is not pulling you away, it's accelerating you straight into the ground to make a nice crater. And before you disintegrate you wish you would have used a 0.25 g weak link. Come to think of it, I really think that the lighter pilots out there fly with weak links too strong for their total weight.

Tad Eareckson - 2008/11/12 05:24:17 UTC

Cragin Shelton - 2001/08/08 09:03:01

On Trusting Weak Links

Reading Joe's last item in the lockout thread prompts me to point out a consideration in the discussion:

NEVER TRUST A WEAK LINK!

Expect two things from your weak link:

(1) It will break unexpectedly at the most inopportune time, with no warning adn no indicaiton of a flight problem.

(2) It will hold strong and fast whenever you move into a lockout. You must never plan or expect on a weak link break. It may well not break when you fly with that attitude. As Joe said, if your situation is new to you and not right, get off tow!

I have never had an instructor use those words to me, but all towing instructors I have worked with have given that message in some form. Pagen & Bryden address it clearly in _Towing Aloft_.
...
So, to repeat: Never trust a weak link. Be prepared to fly off tow in a surprise break at all times when attached, and be prepared to hit the release at all times in case of a surprise attitude change.

2002/08/04 22:14:39
Cragin Shelton
Eastern Shore Weekend

Set up and watched a bit, then got in line for an aerotow about 1:00. First try was a notably short flight, with a weak link break moments after lifting from the launch cart. The wind had shifted, so I had a down-wind landing, rolling in. I succeeded in dragging a knee instead of a toe on one side, so I earned a nice strawberry scrape...

Is this a great communications medium or what!

So by using the 0.5 G bag string he has the worst of both worlds. It breaks at the worst possible times and holds like titanium while he's watching the ground rush at you from the side.

Now why didn't I think of that?

Janni,

You need to start listening to people like the FAA, Dr. Hewett, Steve Kroop, Danny, Brian, Paul Tjaden, the late great Rob Kells... They know what they're talking about. Cragin's just a somewhat less obtuse version of Chris. I can't figure out whether he tosses a coin to decide what he's gonna say next or just reflexively states the opposite of any position I present. In either case - this topic is way out of his stickball league.

Note: While the material on ground based towing weak links by Pagen and Bryden which Cragin is referencing is legitimate enough, their discussion of AT weak links is total crap.

You need to figure out who your friends really are - they're not the ones telling you what you wanna hear.

One little gem of accuracy amongst Cragin's latest steaming pile of bullshit...

Yeah, he's totally right about me having gotten totally sick of standing around watching the soaring window evaporate while the one functional tug that has become the Ridgely norm has to deal with a line clotted by endless and needless relaunches on top of mile high tandems grabbing every third slot.

What he's too dumb to get - despite his own experiences - is that by putting the link in the MIDDLE of the range - as opposed to well off the bottom end - you actually improve BOTH efficiency and safety. More airtime, fewer broken downtubes.

Come to think of it, I really think that the lighter pilots out there fly with weak links too strong for their total weight.

I must say - I admire your consistency. None of the other members of the opposition have ever been intellectually honest enough to take that next logical step.

But step back and ask yourself...

Who are the ones breaking the downtubes and skinning the knees? The big dudes or the little chicks?

We have this great global test population of a decade and a half's worth of aerotowing tens of thousands of pilots ALL of whom have been using the same one size fits all weak link. Are we seeing a trend in which the hobbits are being taken out of the gene pool? Or are we seeing the opposite?

Also ask yourself...

If my motivation in advocating weak link strength 0.6 Gs BELOW the USHPA upper limit is to get people the fuck out of my way at the expense of their safety... How come I'm flying a weak link that holds to a tow line tension of 473 pounds / 1.48 Gs? The guy's an idiot - stay away from him.

David,

I absolutely ADORE complete idiots - the genuine, as opposed to the know-it-all variety. And the less they've towed and learned about towing the better. 'Cause the less they've learned about towing in this hang glider culture the less they've learned WRONG.

Although I'm always happy to see original thinking on any issue... No - you don't wanna be doing that.

You need to understand the point that Danny has so far failed to get across to the bag string crowd.

You can be in a situation in which you are banked on your ear with extremely high tow line tension praying to all the gods you can think of that the weak link holds. I once watched Jonny Thompson interrupt a probable fatal lockout by hitting the gas in a similar situation.

Holly is a near textbook example of what can happen when tension is lost at the worst possible point in a series of oscillations.

Brian,

Thanks much for giving Janni the reality check. It so helps when it's also coming from a source other than me. You got him upset - which means you have him thinking.

He's a smart guy - he'll get it sooner or later.

Brian Vant-Hull - 2008/11/12 14:27:03 UTC

Tad;

what you never get is that insulting someone who's insulted you may gain you creds in a street fight but not in an intellectual discussion. When this whole discussion started many threads ago I felt the same way Cragin did, but since you never insulted me I finally was able to see your side of the argument. Many people who started out with the same belief I did will now never see your side because you get lured into the slap fight. It's hard, but you gotta look past the jabs to gain respect.

If your position is logically correct, people will come around so long as you don't oversell or insult.

You've been overselling by saying weak links CAN'T protect the pilot. They can, though it's not the primary or trustworthy purpose, so it's best not to have them too weak. As for insulting, well...

Janni Papakrivos - 2008/11/12 14:43:50 UTC

Who are the ones breaking the downtubes and skinning the knees? The big dudes or the little chicks?

The ones with bad landing skills.

Gary Devan - 2008/11/12 16:35:18 UTC

Gary Devan wrote:alcoholic/addictive types are doomed if they can't resist that first drink. . .
garyD

Brian Vant-Hull wrote:Tad;
what you never get is that insulting someone who's insulted you may gain you creds in a street fight but not in an intellectual discussion. . . Many people . . .will now never see your side because you get lured into the slap fight. It's hard, but you gotta look past the jabs to gain respect.

If your position is logically correct, people will come around so long as you don't oversell or insult.

Tad Eareckson wrote:But - again - ANYBODY (with half a brain or better) can be an effective volunteer moderator.

quoting him out of context, Matthew wrote:NOTHING IS FOOLPROOF!

Brian Vant-Hull wrote:But you are asking the "moderator", a volunteer, to perform a highly involved and subtle task. However useful and beneficent it may be, it's asking way too much. Sorry to say, you're on your own

the only reason for my writing this post is to back up brian before i totally wash my hands of this. a lot of people, including me, had hoped that the train might stay on the track this time. but i don't know that anyone really believed it would. you've proven them right. don't bother with any apologies, at least not to me, 'cause it won't get you anywhere.

Tad Eareckson - 2008/11/13 18:05:42 UTC

Gary,

Yeah, that response probably seemed overly postal but I was trying to compensate for the many times in the past when I haven't gone anywhere near postal enough. That bridge burning was long overdue.

You have your criteria for people for whom you have and lack respect and I have mine.

There are quite a few apologies owed in this thread and earlier ones on this topic but right now I feel pretty comfortable saying that I'm way in the clear.

But if I happen to see some blinding light down the road I'll let you and everyone else know immediately - whether or not it does any good with anyone. But don't hold your breath.

Brian,

The problem is that whenever Cragin enters an intellectual discussion it immediately ceases to be intellectual.

History time...

The problem with hang gliding is that - decades after the bamboo era - we're still trying to reinvent a couple of wheels. Hang gliders are sailplane/sailboat hybrids and we've wasted a lot of time and lives adapting their technologies and practices.

I recall several conversations with Les King (Sport Flight in Gaithersburg, USHGA Regional Director) in the early Eighties.

In one he related how we had gone to the sailplane community for help and guidance but that they viewed our primitive five to one contraptions with contempt and told us to go fuck ourselves.

Hang gliders were first hooked up to tow lines in an intuitive manner - to the three points of the control frame corners. We used to be able to get off twenty-five or thirty tows before we'd kill someone with that configuration. Not bad.

Then a physicist stepped back, looked at the situation, reconfigured, experimented, verified, and said "Hey folks, you're doing this wrong." He, of course, was treated in a manner not dissimilar to the way I'm being treated now - and Les was significant in the implementation of that treatment.

The essence of what Donnell Hewett did was so simple. Basically - connect the tow line to the heavy part. Just like conventional gliders had been doing well before anybody bolted an engine to one and achieved sustained powered flight.

Donnell Hewett eventually prevailed and Les apologized (to me, at least).

Along with the center of mass concept Donnell established the Skyting Criteria:

http://www.birrendesign.com/rhgpa_criteria.html

which outlined guidelines for conducting safe towing operations.

(Frank got killed because at least two - including the first - of them were violated. Bill and Mike died because two others - not including the aforementioned - didn't come up to snuff.)

When these Criteria were written the towing was all ground based and a lot of the equipment, techniques, and releases sucked. (And when aerotowing first appeared the trikes were too fast and the gliders were too slow.)

The ground based towing also tended to be tension controlled and that mode of operation tends to make weak links pretty much irrelevant.

07: Infallible Weak Link

The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation. (There is always the possibility something unexpected can happen. Breaking point should be appropriate for the weight and experience of the pilot, not to exceed 1G - sum of all towed parts.)

One problem in Dr. Hewett's thinking - then, and to a lesser extent, now - I respectfully maintain, is that it is impossible to define - "the" limit for safe operation - because, as he himself has said:

http://groups.yahoo.com/group/skysailingtowing/message/4597
RE: [Tow] Weaklinks

Donnell Hewett - 2005/02/08 23:28:31 UTC

It is impossible to design a weaklink to release the pilot when he loses flight control because there is no correlation between towline tension and flight control. (A pilot may be in perfect control under high tension but out of control under low tension.)

And thus it is useless to try to scale the weak link to pilot experience. In any case - NOBODY does this. (What we do do (doodoo?) is fly small pilots at high G ratings and big ones at low.)

Two other related problems are the absence of a definition of a lower limit. This absence is based on an assumption that it's always better to be off tow than on and that a weak link can substitute for a release. Both of these - contrary to popular perception - are WRONG.

So all you can do is dial the weak link strength to a point high enough to keep you connected in a situation in which losing the tow would be dangerous (yeah - those situations DO exist) but low enough to keep the tension from getting ridiculous.

We don't need to calculate those numbers - the FAA had done it for us long before hang gliders were as much as a gleam in the eyes of Francis and Gertrude Rogallo.

A couple of months ago - in a context similar to the one at hand - you suggested that I might be an idiot. I didn't respond to that online but my reaction was, "OK, fair enough, what the hell, nobody's perfect."

You and I don't insult each other. We discuss and debate until one of us concedes.

I didn't go postal because of Cragin's stupid insults (although - yeah - that helped). I've been insulted (and worse - misquoted and misrepresented) lotsa times in this thread before without going postal.

I went postal primarily 'cause he's helping to keep aerotowing DANGEROUS - as well as stupidly inefficient.

He reads Pages 59 and 60 of Towing Aloft, locks on like a barnacle to all the stuff they got backwards, and ignores the small fraction they got right which is consistent with what I'm saying.

His mode of operation is to be more concerned with who's saying something than what's being said. Dennis - good! Tad - bad!!.

Then, paying no respect to the points Danny tried to make, follows his usual practice of waltzing into the middle of a conversation he has neither the interest in nor capability of following, making one or two arrogant smug cracks, and then waltzing back out without ever bothering to address anything of substance.

Two summers ago I stated on this forum that Dr. Hewett got it backwards with respect to AT versus ground based weak links. He has conceded that point. That has given me a valuable tool to improve the safety of this aspect of the sport.

In addition to identifying dangerous equipment it's also important to identify dangerous individuals. So I stand by every word of my previous post. History is gonna prove me right on both counts.

If you have any doubts about the trend...

Go back and compare/contrast the vicious reaction I got when I committed heresy and contended that Karen and I should not be flying the same weak link with the general tone now. We don't need Cragin or any other one size fits allers in this conversation.

If your position is logically correct, people will come around so long as you don't oversell or insult.

This is not MY position. This is what we're SUPPOSED to be doing. Just like hook-in checks. It's on the books. We just choose to ignore it. Just like hook-in checks.

As for logic... Everybody and his dog is still mass producing curved pin releases. You KNOW what the consequences of that are. Logic doesn't have a prayer. It's gonna take something more.

Brian Vant-Hull - 2008/11/13 19:18:04 UTC

Yes, it will take something else. But the approach you always slide into is not it. I think Matthew pointed out what needed to be done. But if you write articles nobody will listen unless you write with some humility.

BTW, a highly experienced source who wishes to stay anonymous (call him "Deepfloat") because he doesn't want to get entangled in the name calling (we're all tired of it), has a very interesting point to make.

Deepfloat says the reason 3 strings are used on the tug end instead of 4 is because experience has shown that a 4 strand breaking strength causes damage to equipment, the tug being a far more complex mechanism than a glider. Using a 4 strand weaklink on a glider as advocated for heavier pilots effectively means you don't have a weaklink and will end up with the rope.

The other point Deepfloat makes is that while doing lockout training, the weaklink often will break during the maneuver, despite any physical analysis that says typical tow forces will not be exceeded. Having done many physical analysis myself, I know how frail the chain of assumptions can be. Deepfloat's conclusion is that making weaklinks too much stronger may result in cases where the link could have saved a pilot from a lockout because things happen so fast.

In my particular field of research, the modelers always trust the experimental data, while the experimentalists are cautious with their own data but tend to put too much trust in the model results. This is because each group are honest scientists who know how easy it is to screw things up so are skeptical of their own results.

Tad, you sow doubt because you think you are absolutely right. This is intellectually dishonest. You will be better served by trying to knock down your own house of cards. You give the idea lip service by challenging people to offer counter examples, then proceed to ignore them.

In view of Deepfloat's observations I would say that your scaled stronger weaklink ideas make sense up to an upper limit where the tug is put in jeopardy. After that it just sucks to be heavy.

Tad Eareckson - 2008/11/14 02:07:46 UTC

Brian,

Yeah, well we can slide back out of approaches too - as long as we maintain a dialogue. And - even now - people are still listening. So let's try to recover from that bit of unpleasantness and get this train moving again.

With respect to Deepfloat...

Although I haven't checked lately, Ridgely tugs have always - to the best of my knowledge - used a doubled loop of 130 Greenspot - four strands - incorporated in the bridle. That translates to 400 pounds of tow line tension.

The tandem gliders use the same thing but because the bridle forms a more obtuse angle that weak link only translates to about 348 pounds. That and the fact that the spinnaker shackle chews things up pretty much assures that the tow line stays with the Dragonfly.

While the tug may be multiples of the complexity of the glider the relevant structures aren't. And there's a breakaway in the tow mast in any case.

My feeling is that the tug is supposed to be there to accommodate the glider - not the other way around. If that structure won't allow me to tow at 1.4 Gs - beef it up.

In any case... I'm not worried about ending up with the rope because the chances that I'll ever get that far out of whack before releasing are zilch. They're even less than Karen's 'cause her release actuator is mounted (poorly) on the downtube, she's never broken a weak link, and I always have a finger on the trigger.

Deepfloat's conclusion is that making weaklinks too much stronger may result in cases where the link could have saved a pilot from a lockout because things happen so fast.

I'M STILL NOT HEARING ANY RELEVANT INCIDENT REPORTS.

Lockouts don't kill people. The ground kills people.

A weak link is not there to keep you from hitting the ground. Down low you may get LUCKY and have a weak link break in such a manner as to let you off the hook. You may also get UNLUCKY and have a weak link pop at just the wrong time - as in the Danny and Bob scenarios - and get killed.

That part of the tow MUST be kept under control by the pilots pointing their planes in the right directions and actuating releases at appropriate times. WEAK LINKS CANNOT AND MUST NOT BE THOUGHT OF IN TERMS OF LOCKOUT PROTECTION.

The other point Deepfloat makes is that while doing lockout training, the weaklink often will break during the maneuver, despite any physical analysis that says typical tow forces will not be exceeded.

James Freeman:

Lockouts can and do occur without increasing tow tension up until the point where the glider is radically diverging from the direction of tow.

Yeah, the weak link will ALWAYS break if the lockout progresses long enough. The problem is that the point at which would have happened may be twenty feet underground.

James Freeman:

The purpose of a weak link is solely to prevent the tow force from increasing to a point that the glider can be stressed close to or beyond its structural limits.

Stuart Caruk:

Will weaklinks prevent injuries to pilots who have crappy launch skills and get drug across the ground on launch? Will they protect against lockout, or even a vertical lockout if the pilot is dumb enough to have the line come tight going downwind? Nope and Nope. The weaklink protects the equipment to ensure the pilot has something left to fly. It's up to the pilot to decide if they are capable of flying it. Weaklinks don't make better pilots than reserves do, and frankly they are in about the same class.

I think a weak link is essential. Its sole purpose is to ensure that maximum designed tow forces are never exceeded.

Steve Kroop:

A weak link is there to protect the equipment - not the glider pilot. Anyone who believes otherwise is setting himself up for disaster. The pilot actuating his release is the way to save himself.

I'm telling you, Brian. These people have it right and just about everyone else has it wrong. Let's not make this about ME. This is not about ME thinking I'm absolutely right. This is about ME KNOWING THEY ARE ABSOLUTELY RIGHT.

You give the idea lip service by challenging people to offer counter examples, then proceed to ignore them.

No, I'm doing the best I can but have been pretty overwhelmed. I haven't even BEGUN to deal with Janni's Lucky Break. Stay with me.

Now let's take a look at several things Deepfloat DIDN'T say...

There I was. Thought I was gonna die...

There he was. Thought he was gonna die...

There was this guy down at Quest in '03. There he was. Thought he was gonna die...

In view of Deepfloat's observations I would say that your scaled stronger weaklink ideas make sense up to an upper limit where the tug is put in jeopardy. After that it just sucks to be heavy.

Down low ANY glider with ANY weaklink can put ANY tug in jeopardy. That's why there's a release on that end.

As to the weak link...

The tug pilot can use whatever goddam weak link he wants. The only relevant variable with respect to what the glider chooses is the matter of who gets to keep the rope.

Now let's step back a minute.

I'm not saying anything about the UPPER limit. The USHPA has already codified that as 2.0 Gs. Deepfloat probably doesn't like that so he should probably try to get it lowered. I would oppose that 'cause I think the FAA knows what it's talking about. But I'm only pushing for 1.4.

What I'm saying is we need to specify a LOWER limit. The USHPA says that's 0.0 Gs. As ultimately safe as that is I think it's too low. If you start going up things start getting very dangerous for a while but the risk level goes way down by the time you get to 0.8. I'd push for 1.0 but could live with 0.8 where the FAA has it.

Anybody got a problem with that?

Brian Vant-Hull - 2008/11/14 02:55:38 UTC

Actually, Deepfloat said that during multiple lockout practices the weaklink broke before getting to the release. Too many to catalogue individually. The tension definitely increases above tow forces for a significant percentage of lockouts.

Also, the tug knot looks like 4 but it's actually 3 strands. Said that right up front.

Tad Eareckson - 2008/11/14 13:45:03 UTC

Brian,

I really appreciate having a person for whom science and math are distinctly separated from opinion (as in "It's my opinion that the Earth is six thousand years old and my opinion is just as valid as yours." - which tends to be the norm around here) but I'm hoping that you're planning on responding to my post sometime in more depth than that. I'm putting a lot of effort into and taking a lot of stress as a result of this correspondence and I'd like to hear either concessions or challenges to the points I'm making.

What tends to happen in these exchanges is that I make irrefutable points and the opposition just silently slinks away and the less qualified bulk of the community always slides back to its perennial "Well, Guy B has WAY more airtime than Guy A so he must know what he's talking about." position and stays as stupid as it was when it started out.

Lemme deal with this last issue you just brought up and then hopefully we can drop it because it's pretty much TOTALLY MEANINGLESS. I had reread your previous post before logging on this morning, said "WAIDAMINUTE!", and already written a response which I will now modify a bit.

I'm a REALLY GOOD knot person. I know when I'm looking at four strands and I know when I'm looking at three. If Ridgely tugs are using three strands they switched fairly recently 'cause I can tell you to a certainty that every time I've checked there's been a doubled loop of Greenspot Double Lark's Headed onto the bridle. And I'm DAMNED sure they're still using the same thing on the tandem gliders' bridles. So I'd be real surprised to find out that they're using three in the front and four in the back.

I'm also pretty damned sure they've never actually tested those two configurations because until I pointed out the reality of the situation they were basing their strategy on the assumption that the weak links strength is determined by multiplying 130 pounds by the number of strands. This assumption is completely detached from reality and is the root of just about all of our problems.

I myself HAVE actually tested these configurations and - very surprisingly - while a doubled loop / four strands tests very consistently right around 200 pounds direct load, I got 225 for three.

Now, with respect to the solo lockout drills...

For all but the pixie end of the range of solo pilots the failure of the one size fits all weak weak link is an almost totally random event. They can and do blow anywhere at any time between and including the moment the tug budges forward through separation from the dolly to well into a lockout so severe that it gives one pause concerning one's continuing participation in the sport.

The tension definitely increases above tow forces for a significant percentage of lockouts.

I know this conflicts a bit with the Freeman quote I referenced but...

Well, DUH! Yeah, if you're going this way and the tug's going that the rate of increase in tension will soon become astronomical (which is why, as Dr. Freeman also says, there isn't much of a penalty in terms of roll and/or delay in significantly beefing up your weak link). So what?

The problem is - while in practice and up high were it doesn't matter - down low where it does, lockouts can and do progress to the point at which the pilot is transformed to a lifeless pulp with a one size fits all weak link stressed to only half of its capacity.

So you'd think that those pilots who were unable to release before the weak link failed would have figured out that the weak link can't be counted on the keep them alive during the critical part of the tow 'cause - as far as the exercise was concerned - they got killed.

Actually, Deepfloat said that during multiple lockout practices the weaklink broke before getting to the release. Too many to catalogue individually.

THE WEAKLINK BROKE BEFORE GETTING TO THE RELEASE

I CANNOT FATHOM why anyone in his RIGHT MIND would elect to launch with a release HE HAS TO GET TO. The tugs don't do it - Why do we?

On that issue...




Where's his hand? Where's the release actuator?

If your position is logically correct, people will come around...

YA STILL THINK?

Brian Vant-Hull - 2008/11/10 13:03:30 UTC

After some thought and prodding by an anonymous source I want to lay things out as clearly as I can.

1. We definitely want links that will break when there's a sudden snap in tension caused by such non-normal flight scenarios such as the cart getting hung up in a pothole... In these cases the weak link protects both the pilot and equipment.

WRONG.

During the insomnia session two nights ago I figured out how to explain why the weak link can't do you any good in that sort of situation.

In fact, the ONLY difference a stronger weak link can make is to REDUCE the severity of the accident.

Don't worry, Peter Birren doesn't get this either.

http://groups.yahoo.com/group/skysailingtowing/message/6726
Weaklinks

Peter Birren - 2008/10/27 23:41:49 UTC

I know about this type of accident because it happened to me, breaking four ribs and my larynx... and I was aerotowing using a dolly. The shit happened so fast there was no room for thought much less action. But I wasn't dragged because the weaklink did its job and broke immediately on impact.

The critical element in both of these accidents was not the weak link.

The critical element was topsoil.

Neither of these pilots were hurt 'cause they were dragged. Dragging is a relative non issue until you get to the barbed wire fence at the upwind end of the runway.

These pilots were mangled SOLELY as a consequence of the ultra power whacked induced sudden stop.

We agree that no weak link on the planet can prevent the power whack itself. Right - just look at the pictures.

Things start getting real ugly when the nose digs into the sod. The first thing that happens is that the weak link pops. The next thing is that the pilot - still moving at twenty miles per hour - is gonna swing into the fore underside of the glider going zero miles per hour. Lessee... twenty minus zero... TWENTY! The pilot hits the glider at a closing speed of twenty miles per hour. Lips, larynxes, ribs, necks... whatever.

OK, rewind the tape. This time we're gonna use a quadruple loop weak link and do it again. Same ultra power whack nose plant. But this time the weak link (and - for argument's sake - the back end of the Dragonfly) holds. So for several seconds the glider continues on plowing a furrow at five miles per hour. You still swing into the keel but at a closing speed of only fifteen miles per hour this time.

So the dragging that terrifies everyone so much is actually your best friend and the tea bag string in which everyone places so much misplaced trust is - once again - YOUR WORST ENEMY.

Still having trouble?

Repeat the experiment out on a frozen lake and you don't get hurt at all UNLESS the weak link breaks.

Pretty cool, huh?

Brian Vant-Hull - 2008/11/14 15:24:19 UTC

Actually on a frozen lake you wouldn't get hurt if the weak link breaks because you and the glider will still be doing the same thing since neither is being influenced by friction. On ordinary grass you may be right but it's a complicated enough situation it needs many repeated experiments. Have at it.

If as you say the force increases so quickly a 1.4 G link will be broken a second after a 0.4 G link, then I think your points are logically valid. But anyone (such as Deepfloat and Janni) who has experienced a lockout with a weaklink break will have the gut reaction that weaker may be better. I see it as my job to bring up all objections so they can be discussed without all the name calling destroying the arguments.

Don't know details about the 3 versus 4 string. Table it unless I hear more.

Anyway, I think you may have convinced some people that they can scale up their link without dire consequences. May be the best you can hope for.

Janni Papakrivos - 2008/11/14 17:10:48 UTC

If as you say the force increases so quickly a 1.4 G link will be broken a second after a 0.4 G link, then I think your points are logically valid.

What makes this discussion obsolete is that every argument is based on assumptions which may or may not be valid in any particular case.
A stronger weak link breaking a second later can kill you in a lockout event where that one second places you past the point of no return. That same weak link could save you during a rough launch where a weaker one will break and have you crash. Note that the crash is largely the result of your poor landing skills and judgment rather than the fact that the weak link broke. The scary stuff about weak links not breaking under gradual increase of tension does not worry me, simply because I don't believe that things get out of control in a smooth, gradual way in smooth conditions. Ergo: You can paint death scenarios for whatever weak link strength you use. It makes no difference. If everybody flew with Tad's weak links some would crash and a few would die, too. It's hang gliding, stupid!

Brian Vant-Hull - 2008/11/14 17:44:48 UTC

Tad's point is that non-lockout breaks near the ground are more common than lockout breaks.

(prob of non-lockout break)*(prob of injury due to break) > (prob of lockout nonbreak)*(prob of injury due to nonbreak)

Weather the statistics is correct is debatable. I feel they probably are correct.

Putting the mathematical supposition into words:
"The chances of sustaining serious injury due to a non lockout break near the ground is greater than the chances of having a lockout near the ground and the weak link saving you in a case where you don't have time to release before it gets bad."

The links are more likely to break when the glider gets kicked around, making landing skills a bit less relevant since you may be in a bad situation plus the nose angle used for towing is at stall when the link releases. Most people land on the wheels after a low link break.

People who have downtube mounted releases are more likely to feel they can't release before a lockout than people who have basetube finger pull actuated releases. Tad tried beating that horse a while ago and gave up. may be time to give up on this one.

where the weak link strength sweet spot is located may be a matter of opinion, but if the links are breaking on a regular basis you may want to scale up the strength a bit. Is that such a terrible concept?

Janni Papakrivos - 2008/11/14 20:38:04 UTC

Nobody doubts that a base tube mounted release is better than one that sits on the down tube. That's not the issue here.
As for the rest, you can run your physics equations all day long, I will always trust the empirical data of my own experience and 8 years of safe tow operations at Highland more. I've had a number of close-to-ground weak link breaks that were all non-events. They all broke either for no reason or before the situation got bad. In at least one of those cases a stronger weak link would have made my situation worse. And I'd much rather crash coming off the cart stalled than locking out and nose-diving into the ground because of that extra second. One second can be a LONG time. It's totally beyond me why neither you nor Tad get that. Perspectives change a lot when you don't tow stable gliders anymore, Brian. I'd have a padlock for a weak link if I towed on a Falcon.

Brian Vant-Hull - 2008/11/14 21:04:07 UTC

I tried towing a K2 once, if you recall. Perhaps the hardest glider to tow ever made. 5 breaks in a row, one of them was at treetop level and I had to do a quick and low 360 to avoid gliding into the treeline in front of me (may not have been necessary). I wish I could remember if that was the one time I was scared and released. Having to land before you are planning to when a glider starts acting skittish is not a non-event.

Anyway, the point is that if you are constantly breaking weak links, especially if you are a heavier pilot, scaling up the strength is an option so long as you don't go above the link on the tug end. We lighter pilots have been towing with proportionally stronger links for years, and I think we've been happier. Perhaps the main reason I'm a convert is because I don't feel I have to change a thing.

BTW Tad, I haven't seen a catalogue of broken aluminum due to weak link breaks. Fair's fair.

Tad Eareckson - 2008/11/15 07:25:48 UTC

Brian,

On the ice the glider's gonna slow down faster if the weak link breaks. Nobody needs to do any testing on the grass 'cause there's no freakin' way that something in front of the glider won't break. It's not complicated - just think about it.

As to gut reactions... If weaker is better why does the FAA put the floor at 0.8? Why is it illegal to tow at 0.6? Who are the people having minor accidents on tow? Karen, or everybody but Karen? What would have happened to Janni if he had been in Danny's situation with the same loop of Greenspot? Danny was scared shitless that the weak link would break. There can be no doubt in anybody's mind that this weak link that Janni thinks can do his job for him would have failed and he WOULD have cartwheeled.

We gotta do a lot better than gut reactions.

Janni,

I came off the cart crooked...
over-controlled...
thought I was in control until it broke

This was not a micrometeorological problem.
This was not an equipment problem.
This was a personnel problem.
Relying on a weak link to compensate for an inability to control a glider is not a good strategy for sustained participation in this sport.
Try running that concept by Sunny if you want a second opinion.

You need a weak link that holds about 165 pounds of line tension just to get moving and if you don't think that's enough force to lock you out and kill you several times over you have another thing coming.

Steve Kroop:

A weak link is there to protect the equipment - not the glider pilot. ANYONE WHO BELIEVES OTHERWISE IS SETTING HIMSELF UP FOR DISASTER.

Ya know who Steve Kroop is? Ya think there's a ghost of a chance he knows what he's talking about better than you do? I sure as hell do.

Brian,

Anyway, I think you may have convinced some people that they can scale up their link without dire consequences. May be the best you can hope for.

I HAVE convinced some people to scale up their weak links. But one of the other things I'm hoping for is to get them to understand - as Danny does - that there can be dire consequences to NOT scaling them up to something reasonable.

I spent about an hour and a half getting that point across to Bob Buchanan at the fly-in last summer. He and is Exxtacy had just popped ten in a row. The light bulb came on bright when I pointed out that he and Karen should probably not be flying the same piece of string and I got him up to about 1.1 Gs.

But then some idiot got to him afterwards and dropped him back down well below 0.8. So I'm wondering how come nobody 'cept Janni gives a flying fuck about Karen's safety (1.22).

Janni,

A stronger weak link breaking a second later can kill you in a lockout event where that one second places you past the point of no return.

You can release long before the time split between the weaker and strong links with a half decent release configuration like Matthew, Brian, and I have.

If you were really concerned about your safety at launch you'd be flying with a half decent release configuration like Matthew, Brian, and I have. The safety margin that gives you dwarfs to total insignificance any real or imagined benefit you get from the tea bag string. But:

We wouldn't be flying if it wasn't dangerous.

Janni Papakrivos
Flight Director MHGA

Yeah, that would explain lotsa stuff in this conversation. I can't understand why - with that attitude - you don't keep the brake lever on the downtube AND beef up to 3.0 Gs.

Brian,

The chances of sustaining serious injury due to a non lockout break near the ground is greater than the chances of having a lockout near the ground and the weak link saving you in a case where you don't have time to release before it gets bad.

I know of no instances of anyone getting locked out near the ground so fast that there wasn't time to release. And Janni wasn't locked out and his situation was entirely self inflicted.

People who have downtube mounted releases are more likely to feel they can't release before a lockout than people who have basetube finger pull actuated releases.

This is not a "feeling". They obviously no fucking way can get off as fast as we can. Especially of they fall to the other side where they can't even get back to it. People who ELECT to fly that way are saying, "Hell, I don't need all that safety margin." I'm wondering what the hell the upside to doing it that way is.

where the weak link strength sweet spot is located may be a matter of opinion

I don't think so. I think the FAA knows what it's talking about and that makes the sweet spot 1.4 Gs. Even with the USHPA's floor of 0.0 the sweet spot is 1.0.

1.0 is what the guys at the flight line CLAIM they're handing out to Karen, Kirk, Bob, and Janni so why don't we at least use something that ACTUALLY IS 1.0?

Janni,

Nobody doubts that a base tube mounted release is better than one that sits on the down tube.

BUT HARDLY ANYONE ACTUALLY CONFIGURES THEM THAT WAY.

I've had a number of close-to-ground weak link breaks that were all non-events. They all broke either for no reason...

To the dozen people in line behind you they're not non-events. The five minutes you waste EACH TIME costs a cumulative hour of airtime. The practical effect of one of those "non-events" is just about always that somebody misses the opportunity to soar. You're fucking up some really good days for a lot of people and - again - the only time you appear to have benefited from a pop it had resulted from a situation of your own making.

One second can be a LONG time. It's totally beyond me why neither you nor Tad get that.

Exactly. One second IS a LONG time. And I'd rather spend it twisting my hand and taking care of the problem than waiting around HOPING that something good will happen. But - again - I don't have to wait for that second either. I was off a long time before that.

Perspectives change a lot when you don't tow stable gliders anymore, Brian.

I tow a stiffer handling glider than you do and feel - and AM - a lot safer than you are.

Brian,

We lighter pilots have been towing with proportionally stronger links for years, and I think we've been happier.

You HAVE been happier. And since I moved up to Karen's G ballpark I'm infinitely happier - if and when Janni gives me the opportunity to get in the air. I'm no longer scared shitless of every little bump that comes my way like I used to be. I'm in control now.

BTW Tad, I haven't seen a catalogue of broken aluminum due to weak link breaks. Fair's fair.

On my first flight at Ridgely on their first day of operation I broke their first downtube in a downwind landing following a break. I've watched Dennis Scheele and Victor Koshmaryk break others. All popped for no reason.

But look at it this way. You launch and planes twice as often per hour of airtime - you're gonna get twice as much damage and twice as many injuries and fatalities.

Jeff Eggers - 2008/11/15 13:42:14 UTC
McLean, Virginia

Tad,
How are you fingers doing? Any carpal tunnel symptoms?
You guys are entertaining, even if my never-towed in my life lame butt doesn't understand what the issue is.
Sometimes we just agree to disagree.

Aloha,
Jeff
Jeff Eggers
CHGPA Flight Director
USHPA 82627
FCC KK4QMQ

Tad Eareckson - 2008/11/15 16:19:38 UTC

Jeff,

Thanks so very much for the non hate mail note. Such is always a pleasant surprise and rare treat.

The fact that you've never towed in your life gives you a HUGE advantage in understanding the issue. This is nothing but basic physics and simple logic. Brian's starting to get this but is having to overcome the brainwashing damage done by a couple of decades worth of this culture getting and doing it wrong.

A kid with a kite can get this a lot better and easier than an experienced tow pilot.

Sometimes we just agree to disagree.

Nah, not when it's an issue of science - somebody's right and somebody's wrong. The really smart tow people all converge on this matter. The guy who got his doctorate figuring out how to tow hang gliders is coming my way.

The wrists are doing a whole helluva lot better than the eyes, the AOL dialup connection, and the computers. Huge problems with the latter two. The PowerBook G3 died out from under me yesterday and I had to play musical hard drives with a couple of Power Mac 7300s to get something that worked.

Glad you're enjoying it. Stay tuned.

Danny Brotto - 2008/11/15 17:08:21 UTC

This thing about the FAA regs on weak link strength does in fact allow for a "one-size-fits-most" solution. I am not saying that the FAA recommendations for sailplanes scales appropriately to hang gliders; just want to clear up the reg.

The FAA regs is for the weak link to be between 80% and 200% of the maximum certificated all-up mass of the glider being towed.

The maximum certificated all-up mass of the small Falcon 3 is 235 lbs (45 lbs glider and 190 max pilot.) So using the FAA guideline, a weak link for the small F3 should be between 188 lbs and 470 lbs.

The certificated all-up mass of the large T2 is 358 lbs (73 lbs glider and 285 max pilot.) So according to the FAA, a weak link for the large T2 should be between 286 lbs and 716 lbs.

Combining the two gliders allows for a one-size-fits-most weak link between 286 lbs and 470 lbs.

There are plenty of hang glider pilots flying within the 80% to 200% FAA guideline (or their particular glider rig) that are snapping weak links regularly. Snapping weak links in sailplanes happen but it's not common. I suspect there is some other dynamic that needs to be applied to hang gliders.

I mass out at about 235 lbs so my rig (theoretically at least) has me at a 1.1G link. I have a faint recollection of snapping a weak link once but other than that, my links have stayed intact. I'm rather fastidious about changing weak links every few flights and also not letting them drag around so as to avoid abrasion.

Janni Papakrivos - 2008/11/15 18:13:49 UTC

And Janni wasn't locked out and his situation was entirely self inflicted.

Everything in this sport is self-inflicted.

To the dozen people in line behind you they're not non-events. The five minutes you waste EACH TIME costs a cumulative hour of airtime.

Thanks for confirming Cragin's suspicion.

You can release long before the time split between the weaker and strong links with a half decent release configuration

This is a matter of experience, skill and awareness. I for one always tried to correct the situation rather than get off tow right away. I suspect most people do. I am still inexperienced, so I think it would be way too late for me when I realized I had to get off. Luckily, my tea bag weak link doesn't hold that long.

As for Brian's and Buchanan's examples, I'm as heavy as they come, I'm a whopping 300 lb. package. I towed in nasty conditions. If you break 5 in a row you're either doing something fundamentally wrong or flying in conditions that are fundamentally wrong. None of these examples provide evidence that our weak links are too weak.

Tad Eareckson - 2008/11/15 22:49:17 UTC

Danny,

Yeah, hang gliders can do a one-size-fits-most - but the single loop of Greenspot ain't it.

The maximum certificated all-up mass of the small Falcon 3 is 235 lbs...

I think for the purposes of this drill we oughta min out a Falcon 140 - 42+120=162. Allowable max tow line tension range - 130 to 324 pounds.

So for the one size fits most we narrow the overlap range to 286 through 324 - a target area spanning 38 pounds. That's cutting things a bit fine.

There are plenty of hang glider pilots flying within the 80% to 200% FAA guideline (or their particular glider rig) that are snapping weak links regularly. Snapping weak links in sailplanes happen but it's not common. I suspect there is some other dynamic that needs to be applied to hang gliders.

These hang gliders that are snapping weak links all the time are NOT flying at 0.8. These weak links do not retain their integrity for medium to heavy gliders. These gliders are snapping weak links at 0.5 and less.

http://ozreport.com/forum/viewtopic.php?t=13573
weak links

That's the dynamic that's going on.

I mass out at about 235 lbs so my rig (theoretically at least) has me at a 1.1G link.

I don't know whether you tow two point or off your shoulders. I have you at 1.04 if the former, 1.19 the latter. The fact that you didn't die behind Sunny is a fair indication that whichever of those numbers is relevant is a safe low end. But I'd still feel better at 1.4.

But back to the issue at hand...

A DOUBLE loop of Greenspot IS a pretty good one size fits most. It would max out Karen at 2.0 if she towed one point but only puts her at 1.74 as is and it puts me and Janni at 1.09, 1.25 off the shoulders.

Janni,

Remember about a year ago when you gave me a lot of grief for saying:

Now let's multiply him (Danny) by 1.5 to approximate Janni's hook in weight...

Looks like I was just about right. A bit low actually.

Everything in this sport is self-inflicted.

Yeah, I pretty much totally believe that and wouldn't be flying if I didn't (hence the issue I took with the "shit happens" philosophy expressed last spring).

But some stuff is WAY less self inflicted than other.

Putting a glider out of control is way more self inflicted than failing to check your six before launching and getting bitten by the Mother of All Thermals just off the cart. John Dullahan had this happen to him, did everything else right and fast, and still got a broken wrist out of the deal. He got rolled bad and his tea bag string didn't break. He released. If he had relied on it breaking he would have probably ended up like all the witnesses thought he would.

Bob Koshmaryk got nailed by a dust devil from the side so bad that a tip dragged. He got into a series of oscillations but took control of what was left of the situation and RELEASED at exactly the right time. If his tea bag string had broken at exactly the wrong time it would have been ugly.

Thanks for confirming Cragin's suspicion.

Cragin's SUSPICION? Too bad he never reads the material upon which he comments. Then he wouldn't have to rely on suspicion.

Go back and read my first post in this thread.

Also go back and read THE first post in this thread. I wish everyone had Kirk's concern for participants other than himself.

I've never made any secret of my resentment of this bullshit situation. I've been consistent in that position for years. You stick around at Ridgely long enough and you're gonna start understanding where I'm coming from.

This is a matter of experience, skill and awareness. I for one always tried to correct the situation rather than get off tow right away. I suspect most people do. I am still inexperienced, so I think it would be way too late for me when I realized I had to get off. Luckily, my tea bag weak link doesn't hold that long.

I am quite sympathetic to your position and I agree with your assessment of how most new towers are likely to react. But here's the BIG problem:

Luckily, my tea bag weak link doesn't hold that long.

LUCKILY, your tea bag weak link DIDN'T hold that long. There is every likelihood that it WILL next time. You can't sustain a string of luck (pun not intended initially but it works so well) to ensure your safety.

Cragin Shelton

NEVER TRUST A WEAK LINK!

Expect two things from your weak link:

(1) It will break unexpectedly at the most inopportune time, with no warning adn no indicaiton of a flight problem.

(2) It will hold strong and fast whenever you move into a lockout. You must never plan or expect on a weak link break. It may well not break when you fly with that attitude. As Joe said, if your situation is new to you and not right, get off tow!

I have never had an instructor use those words to me, but all towing instructors I have worked with have given that message in some form. Pagen & Bryden address it clearly in _Towing Aloft_.
...
So, to repeat: Never trust a weak link. Be prepared to fly off tow in a surprise break at all times when attached, and be prepared to hit the release at all times in case of a surprise attitude change.

He has everything EXACTLY RIGHT except the (1) bullshit which is a consequence of using Karen's weak link.

A weak link is there to protect the equipment - not the glider pilot. Anyone who believes otherwise is setting himself up for disaster. The pilot actuating his release is the way to save himself.

Note the consistency in positions.

Here are the relevant parameters defined in the USHGA Aerotowing and Tug Pilot Guidelines in which you must be able to release immediately...

Glider is low and has diverged more than twenty degrees from the tow.
Oscillation worsens at low altitude. Release as the glider is starting to recover from a cycle.
Glider rolls past 45 degrees.
At takeoff the glider climbs so far above position that it threatens to nose in the tug.
When low the glider fails respond to a roll correction within a second.

Learn them, visualize them, and be prepared RELEASE as soon as you recognize one of them happening.

If experience and skill are still such issues that you are not confident of your ability to control the Litespeed at launch then borrow a dumbed down glider for a few pattern tows. Don't expect the weak link to compensate.

If you break 5 in a row you're either doing something fundamentally wrong or flying in conditions that are fundamentally wrong. None of these examples provide evidence that our weak links are too weak.

When a glider breaks a weak link straight and level in smooth air it is one hundred percent proof positive that his weak link is to weak. He's doing something fundamentally wrong but he's doing it before he gets on the cart.

As to flying in conditions that are fundamentally wrong...

IF THEY'RE NOT FUNDAMENTALLY WRONG THEY'RE NOT WORTH TOWING IN.

The more fundamentally wrong the better.

Janni Papakrivos - 2008/11/16 04:04:27 UTC

Dude, what part of "I'm big and my weak links never break in smooth and level flight" did you not get?

Tad Eareckson - 2008/11/16 13:23:41 UTC

Dude,

What part of "I'm bigger, a way more experienced and better ATer, and my links break all the time in smooth and level flight" did you not get?

Now, lemme straighten out a bit and expand on my smart ass response to your clueless smart ass response.

Need to make that past tense of course 'cause I stopped breaking weak links shortly before my brain started kicking in a couple of years ago.

I must apologize 'cause up to this point I had assumed that you were interested in thermalling. I now see that you're interested only in sled rides so I'm revising my recommendations to a strategy which will work out great for all concerned.

Get a Falcon or some other entry level glider and keep it at Ridgely. It'll keep you out of trouble at launch and you'll have absolutely no need for all that performance you're packing now. Keep the Litespeed at home and use it for Strasburg to Harrisonburg runs.

Transfer your Quallaby release and velcro the brake lever up on the downtube as it's presently configured. Neither the extra time and effort it takes to get to it nor the fact that it can spin on the tubing will matter. The tug pilot will always be able to do your job for you - faster, smarter, and better.

Limit your towing to early mornings and late evenings in surface winds of 5 mph or less, ESE or WNW.

The chances of you experiencing a no fault lockout or oscillation will be about zilch and the self inflicted variety almost so.

It may or may not, but if your weak link does happens to break for no reason you land, get back on the cart, and tow again. BFD! Time is seldom critical at those times of day - 'cept you don't wanna miss the spectacular view of the Chesapeake you often get with the sun setting beyond it.

You'll stay extraordinarily safe and the fuck out of the way of the REAL pilots who wanna get up higher than they were dropped off, extend their flights beyond twelve minutes, and max out their airtime earned to gasoline burned ratios.

And you'll never hafta burden your delicate mind with the complexities of the safety issues put forth by the likes of Kevin, Danny, Brian, Paul Tjaden, me, James Freeman, Steve Kroop, Donnell Hewett, and anybody else who knows what he's talking about.

You are hereby absolved from further participation in this thread.

Brian Vant-Hull - 2008/11/16 13:51:48 UTC

Umm, Tad....there are still some things you clearly don't get.

I hereby absolve myself of participation in this thread because the main contributor has no idea how to behave in polite company. This may be permanent and apply to other threads of like nature. I apologize for prolonging this thread by my previous responses.

Tad Eareckson - 2008/11/16 19:13:49 UTC

Ya know, Brian, there are still lotsa things that lotsa people don't get.

One of my goals here is to steer Janni (and everyone else for that manner) away from a luck based survival strategy and help him become a better, smarter, safer AT pilot.

Janni's Lucky Break may very well prove to have been the worst thing that ever happened to him in hang gliding. Maybe he'd have ultimately been a LOT better off if his tea bag string had held - and I can provide GPS track log data to prove beyond all doubt that in a low level lockout situation it is totally capable of doing that beyond any hope of survival - and he survived with nothing more than major bruises 'cause his Litespeed absorbed most of the impact in the course of getting totaled.

I have a REALLY GOOD analogy.

Picture it. 2005/09/17. McConnellsburg. Bill Priday is approaching the Pulpit south ramp with his glider on his shoulders and his carabiner dangling behind him.

I'm gonna give you a time machine but it's the economy model and you only have two choices:
1. Change nothing.
2. Interfere and let him go off unhooked.

And, of course, the answer, given what we all know is gonna happen fourteen days later, is OBVIOUSLY - 2.

We know - statistically - that it's possible to go off the much higher north ramp unhooked, spend a few months of hospitalization and recovery, and resume a very active hang gliding career.

But here's what happened...

He got intercepted by two USHGA Observers who got him connected and sent him off with a fine launch over the scree and the implicit message:

"Hook-in check? Hell, why bother? Ya just had a HANG CHECK fer chrisake! Why worry about the USHGA SOPs? Nah, just do that hang check and you're good to continue carrying your glider into position and launch without another care in the world."

How he or anyone else ever gets off the goddam training hill with a signature on his Hang I rating form is totally fucking beyond me. But he keeps getting away with it and thus having negative reinforcement. And he gets more negative reinforcement from - not one but - TWO - count 'em - TWO Observers. And two weeks later the bottom falls out from under him at a launch at which there is virtually no possibility of survival. And he doesn't.

One more victim of this stupid broken culture.

So, likewise, Janni launches with fuzzy understanding of emergency situations, a glider which is beyond his capability to safely aerotow, and a release which complies with the USHGA SOPs and a daffodil's concept of common sense no better than the foot launch procedure which got Bill snuffed out and comes out smelling like a rose solely because of a dice roll.

And he comes away with this ABSOLUTELY DEADLY negative reinforcement that it's OK to do the hang check and skip the hook-in check - OOPS - I mean - count on a weak link break to compensate for getting into serious serious trouble SOLELY as a consequence of violating about FOUR - count 'em - FOUR provisions and requirements of USHPA SOP 12-02.10.

And, of course, this negative reinforcement spreads like the plague through the AT community which has been baptized in a total cesspool of misinformation anyway.

I've worked my ass off to understand everything I can about the physics, mechanics, procedures, and ergonomics involved in aerotowing hang gliders. What I do is identify the best minds in the sport, parasitize off of everything they have to offer, compile and organize the information, and build on top of whatever I can. Nobody on this turf has a snowball's chance in hell of ever laying a glove on me. 'Cept for Steve - he comes up with a lot of stuff way ahead of everybody else and I've had to follow his lead on a good handful of issues.

Earlier you accused me of giving Janni's (negatively reinforced and disastrous) take on this issue short shrift. I - and you - and Danny - have tried to lend him the benefit of our experience and understanding that understrength weak links are potentially lethal. Yesterday I put a lot of effort into explaining to him why "Anyone who believes otherwise is setting himself up for disaster."

As seems to have become a pattern he ignores the core issues of this topic and comes back with a stunningly rude and disrespectful and bizarrely irrelevant twenty-one word crack.

And you have the gall to criticize ME for my reaction? Like Chris's post was MIGHT have been in the GRAY area? Polite company?!

Brian, I've always GREATLY valued your participation in these discussion 'cause you're often the only one with whom I can have a rational exchange but I'm wondering why you never seem to say much about the attacks but tend to jump all over the counterattacks.

You understand - as few do - that by Janni following this "They can't be weak enough" course of action he "is setting himself up for disaster" and setting an example which, if followed, is very likely to eventually get somebody mangled. So if you decide to walk out of this conversation because you think I'm and asshole - WHETHER OR NOT YOU'RE RIGHT - then maybe you wouldn't have been as valuable a contributor as I had hoped anyway.

Maybe you're the one who needs to do some soul searching.

Janni Papakrivos - 2008/11/16 22:01:59 UTC

Maybe he'd have ultimately been a LOT better off if his tea bag string had held - and I can provide GPS track log data to prove beyond all doubt that in a low level lockout situation it is totally capable of doing that beyond any hope of survival - and he survived with nothing more than major bruises 'cause his Litespeed absorbed most of the impact in the course of getting totaled.

No, but something tells me that your fuel supply had been a lot better off if that had happened. Sorry, dude, but how is it my fault that my weak link consistently breaks when it's supposed to?

Shawn Ray - 2008/11/16 23:36:25 UTC

Tad, Bill did try to launch at the Pulpit Fly-in unhooked... Observers caught him.......Launched unhooked at Whitwell... No one caught it. Why? Not why did no one catch it, but why he did it at all.......Why?.......... Was it adrenaline? Was it rushing? WHY?.............. From that point on I check ALL HOOK- INS! ALL OF THEM! The FEAR of launching unhooked makes me hook in!I NEVER put a good looking sky before saving my anus!I SLOW DOWN when setting up and getting ready to go up to launch. This feels taboo to me talking of launching unhooked.IT should be tatooed on the brain, but is it? Tad, I can appriciate what your angle is........ For my own handle of what happened to Bill.... I painted my carabiner floresent orange, and I had my mother sew me up some wraps for my main made out of material from my hunters saftey vest.Wrap around and little velcro tabs. ORANGE. My main is black like Bill's was . It makes it stand out now. It's just something..... I was thinking about Bill.......
Peace, Shawn.

Tad Eareckson - 2008/11/17 00:08:49 UTC

Janni,

Let's agree to drop the "dude" thing, OK?

Your first sentence is a bit scrambled but I think I got what you meant. If so, you're nowhere near the top of the list I would select for that sacrificial demonstration. The chance that any given individual is gonna make the point dramatically is microscopic. But it's pretty much a certainty that someone is gonna eat runway sometime down the road. We already have a reasonably good local approximation.

Your second sentence...

Your weak link - in this incident we know most about - HAPPENED to pop "Luckily" (to use your adverb) at a point at which its doing so was very advantageous to you.

If you have any respect for any of the top people in this line of aviation you must understand that it didn't pop when it was "supposed to".

I'd really like to know where you got the idea that this is the function of the weak link.

When you say "consistently"... I'd really appreciate hearing about these other occasions when your weak link has failed in such an opportune matter.

In any case... I'm telling you - I got abruptly and severely locked out a hundred feet before the meter was about to expire on my ride up and - even with that release system you said all those nice things about last summer - I ended up thirty feet lower than I started out with the weak link (same as yours at the time) still doing just fine.

Again, I hook up at about the same weight you do - a healthy (unhealthy actually) bit more and if that had happened just off the cart the weak link would not have failed when it was "supposed to".

Of course my reaction time as demonstrated wouldn't have EITHER - but I wasn't scared or on high alert statusas I would have been at launch and I'm thinking/hoping I would have done a lot better down there.

I'm not seeing yet that you understand Danny's point from his first post (2008/11/04) that you can die if the weak link pops when the glider is banked with the low wing stalled. I really wish you would address that issue.

I have seen a glider locked out and almost certainly about to die and the winch operator (Jonny Thompson) hit the gas and pulled him out of danger and on up for a routine release.

I was dumbfounded because the solution was so counterintuitive to what I would have thought and done. That's the guy I most want in front of me in a Dragonfly if I ever get into a similar situation. There a probably lotsa others who would do equally well but I can think of two - based upon past actions and statements - that scare the hell out of me.

In that situation I'd also be scared shitless with a weak link of anything less than 1.4 Gs. Yesterday I made the mistake of saying that whatever Danny was using at the time - 1.04 or 1.19 - was OK 'cause he lived. But we don't know how close to failure he was. I want - and have - a lot more margin.

Thanks for staying in. It may not seem like it but I'm your most valuable and loyal friend in this discussion.

Shawn,

I'll get back to you.

By the way, there was a "like this" missing from near the beginning of Paragraph 14 in my previous.

Danny Brotto - 2008/11/17 02:02:55 UTC

Shawn

Painting the 'biner fluorescent Orange is a fantastic idea! Look, it's really the pilot's responsibility to insure he/she is hooked in but when your bud is about to launch unhooked I think it's a great idea to let them know. And making the 'biner in an obvious color is a sure step in the direction of safety.

As far as negative enforcement, I've witnessed (as a crew) at least a half dozen pilots ready to launch unhooked (yup even at Ridgley.) I've caught it but rather than just tell the pilot that he's unhooked, I've asked for a hang check. The surprise of flopping to the ground is universal. I'm not trying to embarrass the pilot but mainly provide he/she with something to of significance to reflect upon and approach strategies to avert.

Thanks (THANK YOU) for the great safety tip. I think we should universally adopt your practice of painting the 'biner orange; I'm going to do paint mine this week.

Kevin Carter - 2008/11/17 02:51:16 UTC

Tad, I am so far behind this thread, I just arrowed to the bottom. I may have alluded to it before, but I do realize the John Kerry-esque flip flop nature of my points of view. Tog is the high risk poster boy. Fate is waiting at Tog's front step for any number of opportunities. He wrote many checks his body couldn't cash. Losing tow force too low to avoid the prop wash could get Tog. Being too aeronautically challenged to properly tow a glider is another. Your right, I have used both examples with the same main character.

I enter these discussions to inject my opinion that all issues should be discussed. 9 times out of 10 I will disagree with what someone has to say because most problem solvers have that thread of male macho that keeps them from seeing all 360 degrees of the issue.

Not having total control at all times always increases risk. If we had total control then the only cause of accidents would be pilot error . Losing tow force when you want it is bad, not getting rid of it when you don't want it is bad. I step into these debates to speak against any blanket solution. There is no Snake Oil and Rome wasn't built in a day.

I think the mouth release had some great ideas but was not ready for mainstream. That is why I challenged it.
I think looking at weaklinks is a great idea, but not as a blanket solution. If I challenge you its because I harbor skepticism regarding the cause of some of these weak link breaks. I have my own snobbish tendencies and when I go out to fly I can't help but silently criticize what appears to be pilots getting by with just enough proficiency and equipment to pull it off. I have my preconceived notions, and they cloud by opinions of any tow discussion.

Instead of trying to shout over each other to champion our own safety vendetta, lets champion our vendetta's while promoting the other's. While promoting the weaklink discussion, address pilot skill, and when I push for raising the bar on skills, it will include pushinng for appropriate evolutions in equipment.

Deal?

Kev

Tad Eareckson - 2008/11/17 18:01:09 UTC

Oops.

Second paragraph of the previous was written with respect to the Danny (or Holly) losing tension at the wrong time scenario. The strain is getting to me.

With respect to the weak link holding to beyond the point of survivability... We have plenty of examples of those. No need for more volunteer demonstrators.

Shawn,

Yeah, I remember you stating your intention to do that a week after Bill was killed.

Every time we have one of these everybody gets all these brilliant countermeasures ideas they're gonna implement. I salute you for being one of the rare individuals to actually follow through.

Post-Kunio, we beat the total crap out of this issue on the Oz Report Forum:

http://ozreport.com/forum/viewtopic.php?t=13132
Unhooked Death Again - Change our Methods Now?

and arrived at a pretty good consensus - considering it was all hang glider pilots involved in the conversation. I think it will hold up well over time as the last word on addressing this type of accident.

Synopsis (and inserting a bit of my bias)...

There is a handful of good approaches that will help but some are not universally applicable and one can figure out ways to circumvent most all of them.

Prominently - the Aussie method and the bolt-on suspension which encourages it are good but not appropriate for all environments and situations and can be cheated on.

THE KEY - however - is so simple and effective enough so that none of its practitioners has ever had a consequential incident. It's been in black and white staring at us since the beginning of time.

FOLLOW THE FREAKIN' SOPS AND DO THE GODDAM HOOK-IN CHECK IMMEDIATELY PRIOR TO COMMITMENT.

Steve K. Re: Launch procedures
1998/01/12 22:02
chga@idbdnet.com
judymcc@... (Judy McCarty)

Steve Kinsley, who almost launched unhooked once, forwards his thoughts:

Devising a procedure that is proof against distractions and is appropriate in every situation is difficult. I favor hooking in before moving up to the ramp but I don't think there is a single, best answer. And I suspect any grand schemes to force wire crews or pilots to do things in a particular order will just increase the hassle factor and not affect safety. Let me suggest two things: 1. Do a final dip or back step until you feel the strap tighten as part of picking up the glider to launch. 2. Most importantly, concentrate on what you are doing and refuse to be hurried or distracted.

That was a couple more local crowd accidents - half of which were fatal - ago. THIS IS WHAT WE'RE -REQUIRED- TO BE DOING.

The most major thing in Steve's post with which I disagree is what's Most importantly. If you make the final hook-in check an instinctive part of your launch procedure you can withstand a lot of diffusion of concentration, rush, and distraction.

The slightly less major issue I take is that if there is any significant delay after picking up the glider you lift and tug repeatedly as necessary.

We who do this - KNOW - we will never launch unhooked. The procedure is, in fact, tattooed on our brains.

While I do appreciate you contribution and implementation of the orange covering on the suspension and paint on the carabiner...

As Danny alludes, this is of no use to the pilot - only to the crew - IF PRESENT. And the pilot MUST be the focus of this discussion.

I also think that the carabiner itself adds WAY more danger to the equation than the paint on it subtracts. I don't believe you fly in any situations in which quick and easy in and out of the glider is of any benefit. I'd be happier seeing you go bolt-on or speed link.

Was it adrenaline? Was it rushing? WHY?

No. Again...

He was set up for this fatal plunge by ANYONE and EVERYONE who was involved in his foot launch training and recreational hill and ridge flying who permitted him to launch so much as ONE SINGLE TIME without doing a hook-in check and thus in violation of the USHGA SOPs. It's a pretty good bet that - in fact - he NEVER IN HIS SHORT LIFE did a single hook-in check.

This community - and his Instructors and Observers in particular - have a LOT of blood on their hands.

(You're doing these hook-in checks, right Shawn?)

On that note...

Danny,

I once found myself embarrassed at Ridgely when Sea McKeon asked me to do a hang check while I was on deck. I wasn't terribly embarrassed because I would most assuredly have done a hook-in check prior to committing to launch. Even less of an issue than my trademark failure to buckle helmet.

Anyway...

I appreciate what you're trying to do with these potential victims but I actually think you're helping set them up to get killed - EXACTLY as Hank and Cragin did to Bill. The Road to Hell being paved with good intentions thing.

http://www.chgpa.org/forums/viewtopic.php?f=2&t=1153
Hooking In

Steve Kinsley - 2005/10/02 02:45:48 UTC

When Bob Gillisse got hurt I suggested that our local institution of the hang check is more the problem than the solution. I still believe that. It subverts the pilot's responsibility to perform a hook-in check. I often do not see pilots doing a hook in check. Why should they? They just did a hang check and they are surrounded by friends who will make sure this box is checked.

But what if there is no hang check and you are used to one?

DO A HOOK IN CHECK. you need a system that you do every time regardless of how many hang checks you have been subjected to that assures you are hooked in.

(my emphasis)

I am TOTALLY with him on this. The OPTIONAL hang check IS NOT and CANNOT SUBSTITUTE FOR the MANDATORY hook-in check.

Might I suggest that the next time you catch one of these fallible humans you - instead - ask him to pick up the glider, if it's not already on his shoulders, and lift it as high as he can.

This is a very good approximation of what he would have started feeling about eight feet down the north Pulpit ramp, will scare the crap out of him, and will teach him how to do a hook-in check.

Kevin,

Always very happy to have any input from you which your time allows.

Within the realm of honesty - I LOVE flip-floppers. As much and for similar reasons I do complete idiots. If one is not a flip-flopper one has not learned anything since the age of five. If one is not a complete idiot one is not capable of learning anything beyond the age of five.

Within that same realm of honesty but with some intelligence and competence thrown in (and testosterone siphoned off) I also love disagreement and challenges.

Addressing the rest of your post is gonna take more effort.

tow releases
1996/05/09 11:50
chga@lists.air-dc.org
skinsley@DGS.dgsys.com (Steve Kinsley)

Personal opinion. While I don't know the circumstances of Frank's death and I am not an awesome tow type dude, I think tow releases, all of them, stink on ice. Reason: You need two hands to drive a hang glider. You 'specially need two hands if it starts to turn on tow. If you let go to release, the glider can almost instantly assume a radical attitude. We need a release that is held in the mouth. A clothespin. Open your mouth and you're off. sk

Another nail powerwhacked dead center by sk in excess of a decade prior to this point in time at which the unwashed masses have yet to begin to get their shit together.

Janni found himself in what he considered to be a near lethal situation SOLELY and EXACTLY for the same reason that Tog bent his glider and Bill had the life crushed out of his body. All three of them had too much stuff on their cards.

Tog appears not to be remedial. Bill, for an entirely different reason, is definitely not so. I believe Janni is but it's proving to be a very tough slog.

I disagree with one and a half points of your third paragraph. There IS a blanket solution and, while Rome wasn't built in a day, it's been up and running for a long time but very few people have taken note.

At the Currituck stop of the Dragonfly promo tour - 1991/08/02-04 - we had better, safer releases than most people are using now. I don't believe we had secondaries but the primary was simple and cheap and you didn't have to take your hand off the steering wheel to actuate it.

Yeah, I'm a total control freak.

Let's look at the full range of pilot skill/competence range - you being at the top end of the scale, me at the other.

If you tie one hand behind your back I'm almost always gonna be able to fly better than you can.

I can also kick your ass if I give you a glider with an airspeed of five miles per hour and mine has five or six times that.

Although my past flirtations with bourbon, weed, hash, peyote, acid, heroine, crystal meth, plutonium... (the list goes on and on - I can hardly remember anymore) did absolutely nothing to enhance my reaction time as I was led to believe (street dealers are all liars, kids), I can compensate quite a bit for some of those indiscretions by not having to reach for an actuator.

When I start rolling on a cart there are a whole lotta things I don't have to worry about that other people do.

I don't have to worry about finding, reaching for, and triggering a release actuator, a release failure, a bridle wrap, or an overloaded release mechanism.

If I lose tension it's gonna be for one of two reasons: I wanted to or the tug ran out of gas.

I am as much in control of the situation as one can possibly be and not much - if any - worse off than I am in free flight.

Am I perfectly safe and assured of one hundred percent chance of survival? Do I know for certain that I won't be overwhelmed by something too strong and fast for me to handle?

No, but that's no worse than the cards I can get dealt at landing.

Steve and I have gone through some evolutions of the four-string emergency release since its early days. My version of his concept IS a BITCH to adjust but that's a one time issue and, beyond that, the bugs are gone. There is no good reason not to fly one (or two) point without one or another of a couple of options for a hands free release. If you're interested I'll swap what you have for a free upgrade.

If I challenge you its because I harbor skepticism regarding the cause of some of these weak link breaks.

The cause of ALL weak link breaks is EXACTLY the same - They were loaded beyond their capacities. Simple.

If, at the time the weak link broke, the glider was not damaged - assuming it was still in the air - the weak link was not too strong. Also simple.

If the weak link broke when you didn't want it to - It was understrength. PERIOD. Addendum - it was almost certainly dangerously so.

It must be thought of almost exactly as one does a parachute.

It should come into play at about the same frequency and only AFTER the situation has gone to total hell and not WHILE it's salvageable and it can NEVER be counted on to do any good down low.

I have my own snobbish tendencies and when I go out to fly I can't help but silently criticize what appears to be pilots getting by with just enough proficiency and equipment to pull it off.

Totally on board with that. I don't think it clouds anything. Quite the contrary. Clear as a bell.

Instead of trying to shout over each other to champion our own safety vendetta, lets champion our vendetta's while promoting the other's. While promoting the weaklink discussion, address pilot skill, and when I push for raising the bar on skills, it will include pushing for appropriate evolutions in equipment.

Deal?

We don't have "our own safety vendettas". They've always been one in the same. The skills are totally useless without the equipment and the equipment is totally useless without the skills. Lately I've been doing a lot of emphasizing that it is a useless and deadly strategy to attempt to use a weak link as a substitute and compensation for inadequate skills (and equipment).

No deal necessary - we're on the same page.

Now let's team up and beat the crap out of Janni.

Janni Papakrivos - 2008/11/17 23:21:55 UTC

Another example where an understrength weak link would have been desirable...

http://www.youtube.com/watch?v=F_n5B3-MIC4

Tad Eareckson - 2008/11/18 06:20:08 UTC

Janni,

Definitely.

That guy shoulda been using a 0.1 G weak link. This is also the rating that should be mandatory for anyone who believes that a weak link can keep him out of trouble by compensating for incompetence. If he uses one such he'll be right.

Kevin,

Feel free to step in any time. I believe this falls solidly under the jurisdiction of your vendetta specialty.

Marc Fink - 2008/11/18 14:40:21 UTC

Today's word is "intransigent."

Tad Eareckson - 2008/11/18 16:18:16 UTC

Brian,

Thanks much for giving Janni the reality check. It so helps when it's also coming from a source other than me. You got him upset - which means you have him thinking.

He's a smart guy - he'll get it sooner or later.

Lessee... forty words, five mistakes. Quite possibly a new Guinness record for non political speech.

Well - as Brian expressed last spring - I've always been a lot better understanding and developing gizmos than I have people.

I always like to give logic and understanding as much of a chance as possible but maybe we need to look at the way the grownups play.

In the real world the FAA says, "Get it right way or you don't fly - we'll shred your ticket."

USHPA SOP 12-02.10

USHPA Hang Gliding Aerotow Ratings

B. USHPA Aero Vehicle Requirements

6. A release must be placed at the hang glider end of the tow line WITHIN EASY REACH OF THE PILOT. This release shall be OPERATIONAL WITH zero tow line force UP TO TWICE THE RATED BREAKING STRENGTH OF THE WEAK LINK.

Janni's primary release came nowhere near to being compliant with the accessibility requirement and his is secondary release(s) was (were) a joke with respect to capacity.

C. Aerotow Special Skill Endorsement (AT)

The aerotow skill is a demonstration of the pilot's ability to launch and tow successfully and safely behind a flying tow vehicle. ... In order to receive the endorsement, a pilot must demonstrate the following to an Aerotow Official:

2. ...a complete discussion of all those factors which are particular to the specific aero tow system used and those factors which are relevant to aero towing in general.

http://groups.yahoo.com/group/skysailingtowing/message/4597
RE: [Tow] Weaklinks

Donnell Hewett - 2005/02/08 23:28:31 UTC

It is impossible to design a weaklink to release the pilot when he loses flight control because there is no correlation between towline tension and flight control.

Janni Papakrivos - 2008/11/15 18:13:49 UTC

Luckily, my tea bag weak link doesn't hold that long.

http://groups.yahoo.com/group/skysailingtowing/message/6744
Weaklinks

Donnell Hewett - 2008/11/05 21:22:29 UTC

I am sure you can imagine more than one situation where getting off line is the worst possible alternative you can take. In such cases, the towline becomes a "lifeline" rather than a "death-line".

Danny Brotto - 2008/11/04 12:49:44 UTC

...if the weak link had broken, the downwind wing would have further stalled and I would have cartwheeled into terra firma...

Janni Papakrivos - 2008/11/03 19:29:05 UTC

They can't be weak enough in my humble opinion...

Janni Papakrivos - 2008/11/11 19:47:49 UTC

Tad Eareckson - 2008/11/11 04:27:11 UTC

The weak link that saved his butt in that situation is the same one that's gonna break his freakin' neck in Danny's or Bob's.

No it won't, because it's so wonderfully understrength.

(Note: BECAUSE IT'S SO WONDERFULLY -UNDERSTRENGTH-?!?!?!!!!)

2. (continued...) Must demonstrate complete understanding of ... emergency procedures ... and the indications of an impending emergency and convince the instructor of his ability to execute emergency procedures.

Janni Papakrivos - 2008/11/11 19:47:49 UTC

I probably wouldn't have released ... Because I thought I was in control until it broke...

4. Demonstrates successful, confident, controlled launches and flight under tow to release at altitude, with a smooth transition to flying, with proper directional and pitch control resulting in proper tracking of the aero tow vehicle in both straight and turning flight and appropriate maintenance of proper tow line tension and airspeed. Should demonstrate the ability to control the glider position relative to the aero tow vehicle. Such demonstrations should be made in typical soaring conditions. A minimum of 5 such successful demonstrations must be made.

Janni Papakrivos - 2008/11/03 19:29:05 UTC

I came off the cart crooked in my Litespeed, over-controlled and would have quickly been in a close-to-ground neck-breaking lockout if...

(he hadn't lucked out after - through no fault of Mother Nature's nor anyone but his own - he commits, in the course of his very short dolly launch career, what is - to my knowledge - the most dangerous launch in the forty thousand flight / ten season history of Ridgely aerotowing).

So Janni,

Given the above and the fact that you don't even have - or come anywhere close to qualifying for - an AT signoff, what makes you think that you're qualified to enough to contradict and ignore the points of people like Donnell Hewett (who was getting his doctorate in the physics of hang glider towing well before you had figured out how to make and launch paper airplanes in early primary school), high volume commercial tow operators, and lotsa top guns in the competition arena?

Janni Papakrivos - 2008/11/18 18:23:38 UTC

I'm so sorry Tad. I didn't realize this discussion and your weak links were only intended for pilots with expert aerotow skills. You're right, of course, if one is that good one can fly with stronger weak links. What the hack, perhaps pilots of your caliber don't need one at all on your end of the tow line. It's just that for every situation speaking in favor of stronger weak links I can easily think of a counter-example where an understrength weak link is preferable. A tow line can be a lifeline, it can also be a deathline, I'd give that a 50/50 distribution.
Whatever I choose, I will never be 100% safe. That's why I couldn't care less about your weak links.

Tad Eareckson - 2008/11/18 23:04:32 UTC

Janni,

What, exactly, do you mean by "MY" weak links?

In eight of the ten seasons of Ridgely operation Karen has been flying a weak link 1.6 times as strong as mine - with much more success and safety margin than yours truly. Only in the past two seasons have I been flying a weak link fifteen percent stronger than hers.

So let's give credit where credit is due. These are MUCH more KAREN'S weak links than they are mine.

Who said anything about "EXPERT" aerotow skills?

I was referencing the absolute MINIMUM aerotow skills - and, much more importantly, UNDERSTANDING - that are required for a goddam Hang II to get his ticket.

Having "expert" aerotow skills is EXACTLY like having and expert tic-tac-toe playing skills. There isn't much to it, it doesn't take much in the way of brains, you can only get so good at it, and it gets REAL boring REAL fast.

I'm not particularly worried about your SKILLS - although I think they were alarmingly poor at the time of this incident. They're probably at least adequate now and for all I know you will tie or eclipse me on your next flight.

I am, however, extremely concerned about your crappy noncompliant equipment and your abysmal lack of compliance with USHPA SOP 12-02.10:C:2.

You could do a reasonable job of bringing your equipment up to snuff by mounting your brake lever on your basetube - like Matthew did - and swapping out those bent pins with which everyone is so enamored with some good ones. Just doing the former would bring your safety margin WAY up.

But right now your understanding of the principles of an aerotow system and emergency procedures REALLY SUCKS - possibly almost as much as just about everyone else's.

I'd like to see you understand that AT pilots of just about ANY caliber can tow without weak links as safely as they can fly without parachutes.

A tow line can be a lifeline, it can also be a deathline, I'd give that a 50/50 distribution.

I AM REALLY REALLY HAPPY TO -FINALLY- HEAR YOU ACKNOWLEDGE THAT. We now stand a chance of making progress.

Let's look at the 50/50 part of that statement...

I know of only four relevant incidents at Ridgely - one more than has been referenced in this discussion.

I watched John Dullahan launch on Runway 120 while Bruce was predicting what would happen. John (according to Bruce who was standing next to me) reported that John was trying to use weight shift to correct the cart heading (instead of just staying centered and letting the cart and towline take care of things automatically).

As soon as he separated he found himself in a really spectacular and prolonged lockout to the right.

It wasn't scary looking though 'cause he was climbing the whole time. His weak link DIDN'T BREAK and he eventually released and had plenty of time to put an uneventful landing together.

We have yours which was entirely self inflicted.

We have Danny's which was partially self inflicted - pitch trimmed too high on the cart, moderate 90 cross.

And we have Bob Koshmaryk's. It could be argued that his was, to some extent, avoidable but I would be quick to say that anyone trying would be full o' shit. That's the one in forty thousand tow that could happen to ANY of us.

So John's was pretty much irrelevant. Totally self inflicted, not dangerous, weak link didn't need to break, weak link didn't break, pilot released at leisure and altitude.

Yours. Totally self inflicted, extremely dangerous, no recognition of seriousness of situation, lucky break. Lucky break not apt to be repeatable for a sustained series.

Danny's. More or less self inflicted but a scenario which can result solely as an Act of God nevertheless. Consequence of losing lifeline potentially lethal. Gained control of situation and flew away unscathed.

Bob's. Pure Act of God and validation of Danny's situation. Gained control of situation, released, and landed unscathed.

So I'm seeing this as more of 0/100 distribution.

Whatever I choose, I will never be 100% safe.

Maybe. But I think ALL of us CAN and SHOULD be 99.999 or better percent safe. But not if we lack the skills to exercise maximum control of the situation or allow ourselves to be robbed of the ability to do so by a roll of the dice.

That's why I couldn't care less about your weak links.

I got a little momentum going with the Tow Committee so, with a lot more work and a little bit o' luck I just might be able to MAKE you care.

But don't lose any sleep - nobody every actually enforces safety rules in this bullshit culture anyway.

Tad Eareckson - 2008/11/19 00:07:29 UTC

(Make that "ever".)

Oops. Missed a really obvious tic-tac-toe analogy...

The ONLY way you can lose is to do something REALLY STUPID.

And if you have a downtube mounted release actuator and a weak link under 1.0 Gs you've already more than fulfilled the requirement.

P.S. Note that the two guys who lived because their weak links held were both lightweights - Danny's already given us his stats and Bob's a skinny high school kid.

Bacil Dickert - 2008/11/19 00:24:54 UTC

Hey Janni,
You have a choice that would enable you to be 100% safe (relative to towing). You can choose not to tow. Without being tethered to a tow vehicle it's all on you. No extra variables to worry about. No weak link (strength) to argue about. Disclaimer: This is not a anti-towing message.

Shawn Ray - 2008/11/19 01:04:33 UTC

It stands out better against the black harness. Yeah, I guess I did that because of an accident, but it was something easy to do and it stands out better now......It is, The Pilots Responsibility ! I check others anyway. I don't ever want to see.............
Shawn.


orange carabiner

Danny Brotto - 2008/11/19 02:18:00 UTC

Tad Eareckson - 2008/11/15 22:49:17 UTC

I think for the purposes of this drill we oughta min out a Falcon 140 - 42+120=162. Allowable max tow line tension range - 130 to 324 pounds.

Now you are making stuff up. If you are going to use the FAA (and I'm not saying their rules apply to HGing) as a guide, then it's the maximum certificated weight not some made-up 160 lbs + 42 lbs scenario. The published all-up weight of the small F3 is 235 and that's what the 80% and 200% (186 lbs to 480 lbs) should be applied to in a one-size-fits-all scenario.

If an individual pilot fits the 162 lbs all up scenario, then he/she can use the lower pull break accordingly.

BTW on that video, the weak link does seem to break as the HG pilot begins that second roll-out. What he did to regain control tells me that he had no capability (and he had enough scenario to regain control once off tow.) I suspect that either there was something wrong with glider or he was totally inexperienced at flying such a glider and it got totally away from him.

Marc Fink - 2008/11/19 09:12:02 UTC

Bacil Dickert - 2008/11/19 00:24:54 UTC

Hey Janni,
You have a choice that would enable you to be 100% safe (relative to towing). You can choose not to tow. Without being tethered to a tow vehicle it's all on you. No extra variables to worry about. No weak link (strength) to argue about. Disclaimer: This is not a anti-towing message.

Of course it is!

Brian Vant-Hull - 2008/11/19 14:09:42 UTC

Janni;

Janni Papakrivos - 2008/11/18 18:23:38 UTC

...for every situation speaking in favor of stronger weak links I can easily think of a counter-example where an understrength weak link is preferable. A tow line can be a lifeline, it can also be a deathline, I'd give that a 50/50 distribution.

If you really believe the dangers of a weak and 'strong' link are equal, why use the one that causes the inconvenience of having to trudge your glider back to the tow line more frequently? Scale it up proportional to mass but keep it weaker than the one on the tug end. If you join the happy minority with their fingers on the release you might be more willing to make the change.

Yes, I know I said I wasn't gonna participate anymore, but this was so obvious I couldn't believe others had passed it up.

Tad Eareckson - 2008/11/19 14:36:14 UTC

Danny,

No, I'm not making stuff up.

I'm on dialup so I haven't yet dared to download the nine meg Falcon 3 manual so I used the 2005 edition.

The allowable hook-in weight range for the 42 pound Falcon I 140 is listed as 120 to 210 pounds. The minimum is about Karen minus the parachute and Camelbak. This gives us a hook up weight range of 162 to 252 pounds. The top is comfortably over one and a half times the bottom end.

I didn't say anything about using the FAA as a guide. What I said was "for the purposes of this drill".

The FAA isn't terribly concerned nor wants to deal with the range of stuff that goes in a sailplane cockpit - It represents a much smaller percentage of the package than the stuff on a hang glider between the carabiner and basetube.

The USHPA - appropriately - says nothing about the maximum certificated operating weight and is concerned - appropriately - only with the stuff on the cart prior to any given launch.

The FAA model for this glider mandates that Thirsty Karen tows between 1.04 and 3.11 Gs. Her max would be 31 pounds above my mid.

Danny Brotto - 2008/11/19 02:18:00 UTC

I suspect that either there was something wrong with glider...

Yeah. Something seriously wrong right between the carabiner and basetube. Look no further. He launched like his was coming off of the back of a truck and that was the high point of his performance.

Kevin,

Did the glider look familiar?

Brian,

Good one. Thanks. Wish I had thought of that.

Hope you'll stick around and help me with a few more such gems.

Janni Papakrivos - 2008/11/19 17:08:45 UTC

Tad Eareckson - 2008/11/18 23:04:32 UTC

You could do a reasonable job of bringing your equipment up to snuff by mounting your brake lever on your basetube - like Matthew did - and swapping out those bent pins with which everyone is so enamored with some good ones. Just doing the former would bring your safety margin WAY up.

This discussion is not about release mechanism. It's about stronger weak links vs. weaker weak links. Actually, it's about weak links that break vs. no weak links at all as revealed by the following statement

I'd like to see you understand that AT pilots of just about ANY caliber can tow without weak links as safely as they can fly without parachutes.

#1: Pilots generally do not deliberately release in close-to-ground oscillations. They generally hang on to fix the problem, or don't realize they've got a problem until the glider is banked 90 degrees and beyond. An understrength weak link would break before that happens. If you watch the video closely, you will see that the pilot is out of position way before things go sour. I don't care if you think he's incompetent, that's beside the point. With my configuration the weak link would have yielded right there. A good thing.

#2: I believe weak links should protect the pilot as well. Considering a tow line a lifeline is complete hogwash. I think they should reliably snap as soon as you're out of position or start oscillating. One thermal can bank an oscillating and otherwise manageable glider past the point of recovery. A weak link break or deliberate release at that point is too late for you'll hammer in with a lot of speed to boot. Landing in the prop wash of the tug is as likely but safer.

#3: I will next season, provided I get permission, deliberately lock out at 2500' in a gradual way in a series of experiments to see whether my weak link breaks consistently and at what bank angle it would do so. If it allows me to enter a full lockout, I may ask Tad to make me a 0.75 G weak link that breaks at precisely that pull force

Brian Vant-Hull - 2008/11/19 17:25:59 UTC

Though theory may say you can go into lockout without breaking the weak link, we all know theory is crap and I applaud your decision to test it. I just know that if it was me, no matter how much I said I wanted to test it I'd get spooked and be pulling the release long before I hit lockout.

You need a damn-the-consequences full throttle test pilot. Maybe Ellis is available?

Tad Eareckson - 2008/11/19 19:29:45 UTC

Janni,

An airbag has never been a factor in the safety of one of my (or anyone else's) drives to Ridgely. Had it been disabled my face would look exactly the same as it does now.

(Insert joke of choice here.)

I want it in place at all times but I don't want it going off every time a piece of gravel gets kicked up by a semi and bounces off my license plate. That would make the drive more dangerous.

For non aerobatic flights in the entire history of CHGA/MHGA we have had - to the best of my knowledge - only ONE parachute deployment. It happened because a bulky handle was amended to the deployment bag and caught on the basetube - exactly as the pilot had been warned.

So, within the above context, parachutes haven't made us any safer - quite the contrary in fact.

Janni Papakrivos - 2008/11/19 17:08:45 UTC

I don't care if you think he's incompetent, that's beside the point.

His unquestionable incompetence seems to be blindingly obvious to everyone but you and is ENTIRELY the point.

Pilots generally do not deliberately release in close-to-ground oscillations.

Under the USHGA Aerotowing and Tug Pilot Guidelines, tug and glider pilots are REQUIRED to release at low altitude if oscillations worsen.

They generally hang on to fix the problem, or don't realize they've got a problem until the glider is banked 90 degrees and beyond.

Under the Guidelines they are REQUIRED to release at half that bank angle. If they're too dense to realize they have a problem they have no business hooking into a glider at the airport, the Pulpit, or Jockey's Ridge. The Pilot Proficiency Program is in place to prevent them from doing so.

In the case of what I believe is the ONLY low level oscillation incident over to occur at Ridgely the pilot did, in fact, handle the situation perfectly.

http://groups.yahoo.com/group/skysailingtowing/message/4597
RE: [Tow] Weaklinks

Donnell Hewett - 2005/02/08 23:28:31 UTC

It is impossible to design a weaklink to release the pilot when he loses flight control because there is no correlation between towline tension and flight control.

James Freeman:

The purpose of a weak link is solely to prevent the tow force from increasing to a point that the glider can be stressed close to or beyond its structural limits.

Stuart Caruk:

Will weaklinks prevent injuries to pilots who have crappy launch skills and get drug across the ground on launch? Will they protect against lockout, or even a vertical lockout if the pilot is dumb enough to have the line come tight going downwind? Nope and Nope. The weaklink protects the equipment to ensure the pilot has something left to fly. It's up to the pilot to decide if they are capable of flying it. Weaklinks don't make better pilots than reserves do, and frankly they are in about the same class.

I think a weak link is essential. Its sole purpose is to ensure that maximum designed tow forces are never exceeded.

Steve Kroop:

A weak link is there to protect the equipment - not the glider pilot. Anyone who believes otherwise is setting himself up for disaster. The pilot actuating his release is the way to save himself.

http://www.chgpa.org/forums/viewtopic.php?f=2&t=2467
weak links

Danny Brotto - 2007/05/16 23:15:19 UTC

Weak links are not a secondary release system...

These people all know what they're talking about. You don't.

And nobody who makes as statement like:

Considering a tow line a lifeline is complete hogwash.

has any business owning a card with "AT" stamped on it.

Janni Papakrivos - 2008/11/19 22:21:40 UTC

http://groups.yahoo.com/group/skysailingtowing/message/4597
RE: [Tow] Weaklinks

Donnell Hewett - 2005/02/08 23:28:31 UTC

It is impossible to design a weaklink to release the pilot when he loses flight control because there is no correlation between towline tension and flight control.

Agreed. Irrelevant, however, since loss of line tension renders any weak link ineffective and is, therefore, of no concern in this discussion.

How about this:
It is possible to enter situations that encompass rapid buildup of towline tension beyond what is normally employed to commence launch,
requiring the pilot to quickly release if loss of flight control is imminent.
It is possible to reach the point of no recovery before the decision to release is made.
It is possible to design a weak link to release the pilot entering situations that encompass a rapid buildup of towline tension beyond what is normally employed to commence launch.

No?

Tad Eareckson - 2008/11/20 01:58:06 UTC

Agreed. Irrelevant, however, since loss of line tension renders any weak link ineffective and is, therefore, of no concern in this discussion.

No, it's not irrelevant. In your previous post you were talking about trying to hit a sweet spot which would protect the pilot. And Donnell's statement encompassed a lot more than loss of tension.

It is possible to enter situations that encompass rapid buildup of towline tension beyond what is normally employed to commence launch,

Yeah...

requiring the pilot to quickly release if loss of flight control is imminent.

Yeah...

It is possible to reach the point of no recovery before the decision to release is made.

Yeah... But now it starts getting a little complicated.

If the pilot is either incompetent or brain dead or, as is the usual such case, some combination of the two the decision to release may be made a couple of weeks later when he regains consciousness. Such is also the case regarding this pilot's decision to correct a roll prior to clearing the slot at Woodstock.

But I know of no Dragonfly dolly launch situations that could have been controlled better and faster by the weak link than the pilot.

It is possible to design a weak link to release the pilot entering situations that encompass a rapid buildup of towline tension beyond what is normally employed to commence launch.

No?

Yeah, fer sure. BUT...

- Problem 1

Tow line tension two or three times what is required to get the cart rolling may be the ONLY thing keeping you alive in an oscillation situation - such as Holly's or Bob's.

- Problem 2

You can be low and locked out / totally out of control / no way coming back and still wanting to stay on tow for a good while longer. Rob Kells pointed out to me that if you're rolled but CLIMBING it's probably a good idea to stay on line to give you more altitude with which to get back level after you get disconnected for one reason or another.

This was, in fact, EXACTLY what happened in the only incident of low level lockout at Ridgely of which I am aware. John Dullahan waited a LONG time to release and, consequently, had plenty of time and altitude with which to recover.

- Problem 3

You can be rolled and have a wing stalled - as was Danny's situation - and dependent upon the lifeline for survival.

- Problem 4

You can be low relative to the tug and mushing - as was the Bill and Mike tandem situation - and desperately in need of twice as much tension you're getting. (They didn't.)

- Problem 5

For me it takes about a third more tension to get the cart rolling than I'm feeling aloft. That extra forty pounds is plenty enough to lock me (or you) out and hold long enough to preclude your survival. Mike Haas - 2004/06/24.

So by trying to hit this totally fictional sweet spot you're throwing away certain survival options in four of these documented scenarios for a dice roll which can only MAYBE be of any value in one and then only if you're not doing your job.

The lighter pilots are flying higher Gs with the one size fits all weak link and thus having fewer problems. They're the serendipitous winners of this game.

Amongst the heavier pilots there's a distinct directly proportional relationship between weak link rating and IQ. Think about joining the club.

Brian Vant-Hull - 2008/11/20 13:16:41 UTC

The lighter pilots are flying higher Gs with the one size fits all weak link and thus having fewer problems. They're the serendipitous winners of this game.

This was what convinced me, though I admit in large part it was because I don't have to do much (I'm around 1 g). If I was around 0.5 g I'd be kicking and screaming to prevent having to make a change. I also admit that if I had a bicycle release instead of a lookout pullstring release, I'd be slow to make the change. It's the same reason I'm not a vegetarian: I tend towards moral indolence.

Yes, there are dangers to increasing the weak length strength, but since I'm concentrating so hard when near the ground and I have my finger literally on the release, I can deal with it faster than the link can. Up high when I'm dozing off it's not quite as critical. Deepfloat points out that once you are definitely in a lockout situation (in this case deliberately induced, and most likely you would have released before this) the weaklink often does tend to break before the pilot panics and releases, but since nobody's making weaker weak links for light pilots, stronger weak links for large pilots are indicated.

Just don't go above what the tug has or you'll get the rope and be unhappy.

Tad Eareckson - 2008/11/20 14:42:28 UTC

Bacil,

Appreciate you following a thread which has pretty much zero relevance to your range of flying.

What follows is something I started focusing in on a couple of days prior, but anyway... Thanks for the great segue.

In addition to the nonsense about backup suspension being installed to enhance safety and needing twelve thousand pound locking steel carabiners on eighteen hundred pound gliders we have a few deadly popular myths in this culture, mostly originating in efforts to reinvent wheels that have been working perfectly well in mainstream aviation for the past century.

Ones that come to mind (which we've recently discussed)...

"Don't even consider rolling in for a landing like everybody else does. If you wanna stay really safe you take your hands off the steering wheel at a critical point in the flight, move them to the downtubes, and whip stall the glider at a precise moment to instantly go from eighteen to zero miles per hour."

"A hang check is mandatory and supersedes the optional hook-in check."

"A weak link is a release mechanism which ensures that the glider doesn't get out of control and keeps the pilot safe."

Here's another one:

"Being off tow is safer than being on."

IT IS - IN FACT - HUNDREDS OF TIMES SAFER TO BE ON TOW THAN OFF!

Stop thinking of the kite as a glider and start thinking of it as a Cessna. The tow line is your engine.

Which is safer? A little plane with water in the fuel lines whose engine abruptly cuts out at random points in the takeoff about one out of ten times or one preflighted and flown by a sane person?

Cessnas can get hit by the same crap we do and get kicked around a bit at takeoff. The procedure for dealing with it is not to immediately and irrevocably kill the engine, come up with a Plan B, start over from scratch, and repeat as necessary.

Granted, the analogy breaks down in the case of a low level non climbing lockout, but the instances of those that have progressed so fast that the weak link can come into play faster than the pilot can react are NONEXISTENT (although it may be within the capability of a really determined pilot to deliberately induce one).

The 250 feet of hollow braid Spectra between Dragonfly and glider is virtually ALWAYS a LIFELINE.

Climbing out is ALWAYS safer than landing.

The tow line - as has been demonstrated locally over tens of thousands of tows - is your best friend. But the typical knee jerk reaction is to malign it as your worst enemy.

The reason for this is that it has emerged from a history (ongoing - to no small extent) in which there was often a lot of crap and incompetence in the vicinity of BOTH ends and it took the rap - coming away with a reputation it didn't deserve and is having a hard time living down.

You have a choice that would enable you to be 100% safe (relative to towing). You can choose not to tow. Without being tethered to a tow vehicle it's all on you. No extra variables to worry about.

Free launcher or tower - Gravity is the common enemy here. It ultimately deposits you on terra firma - the nasty crap that is the only stuff that can hurt you in this sport.

The primary "worrisome" extra variable with which the tow heads are dealing is thrust - just one more very important weapon against the evil gravity force.

In ridge launching you have several tools for putting daylight between terra firma and yourself.

1. You can develop thrust - a la Flintstone - in the course of getting airborne. But once you have - that tool is history.

2. You have the advantage that - as long as you're pointing the right way - terra firma is receding away from you. The downside of that is that if you get pointed the wrong way - tree, boulder, and Timber Rattler infested terra firma starts closing at an alarming rate.

3. If strong smooth ridge lift is present you can pretty much dispense with the thrust drill and easily and safely climb away from the receding terra firma. The downside of strong smooth ridge lift is that - while you're almost guaranteed to survive the launch - you're also almost guaranteed to die of the ensuing boredom.

4. You can use a thermal cycle as substitute for ridge lift to help clear a slope. The ensuing flight is apt to be a lot more interesting but so might the launch itself.

Comparing/contrasting AT launches...

1. As long as the tug pilot takes an occasional glance at the gas tank - we have unlimited thrust.

2. The terra firma is flat and thus of no aid in increasing the separation rate but if you get turned it doesn't come back up to smack you in the face. It's all mown grass, there are no trees or boulders, and the snakes tend to be Rat, Racer, Hog-Nosed, and Water (try to avoid the Water if you ever have to make a choice).

3. We don't have the terrain to produce strong smooth ridge lift. In the conditions that produce it however, there are two directions in which the launches get really easy but the ensuing flights are infinitely more abysmal than their mountain counterparts.

4. Thermals are mandatory up high, annoyances during the bulk of the tow, and, while rare and mostly avoidable during launch, potentially very dangerous - but magnitudes less likely and probably no more dangerous than the ones at the ramp and almost always quite manageable with tools available.

So now let's start looking at local anecdotal data...

Ed Reno, Chris Miller, John Coleman, Steve Kinsley, me, Chris McKee, me, Ed Tom, Raean Permenter, Bob Gillisse, me, Marc Fink... Somebody wanna help me out with ridge launches with bothersome and/or unpleasant consequences? It's been a while.

So what do we have from Ridgely launches? Yeah, they haven't spanned the time but they've pumped through a lot of volume. The ONLY stuff we have are a skinned knee and a few broken downtubes and ALL of those happened BECAUSE the lifeline was lost BECAUSE of UNDERSTRENGTH weak link breaks.

I can think of about four flights originating from Ridgely that were immediately followed by trips to the hospital and ALL of them happened well after normal releases at altitude.

You lose that lifeline at the critical stage of launch... You:
- ARE coming down at a pretty much fixed time and location not of your choosing.
- lose:
-- airspeed - Your angle of attack suffers greatly.
-- margin to recover from a stall - tip, partial, or full.
-- the ability to recover from an oscillation (see Holly Korzilius - 2005/05/29).

No weak link (strength) to argue about.

The people who have their shit together know there is no argument and dial in right around 1.4 Gs.

Anyone who believes otherwise is setting himself up for disaster.

Disclaimer: This is not a anti ridge flying message. (And I'm not trying to be smart ass about that.)

Janni Papakrivos - 2008/11/20 15:30:46 UTC

I think there are dangers to increasing their strength and I think there are dangers to flying with understrength weak links as well. It all depends on what risks you're more comfortable taking.

Being off tow is safer than being on

Sometimes yes, sometimes no.

Stop thinking of the kite as a glider and start thinking of it as a Cessna. The tow line is your engine

Nonsense

Climbing out is ALWAYS safer than landing

What you mean here is staying on tow is always safer than landing (you don't climb in a lockout all that great), and that's nonsense as well.

You can be low relative to the tug and mushing - as was the Bill and Mike tandem situation - and desperately in need of twice as much tension you're getting.

Irrelevant, weak links don't create line tension.

For me it takes about a third more tension to get the cart rolling than I'm feeling aloft. That extra forty pounds is plenty enough to lock me (or you) out and hold long enough to preclude your survival.

Sounds reasonable, it's just not backed by what I've personally experienced. Perhaps I found the sweet spot? I will extensively test that next season.

Marc Fink - 2008/11/20 17:34:44 UTC

To lockout or not to lockout..therein lies the rub,
Perhaps kind sir, thou knowest not what it is, much less hath not experienced it's vile temperament.

marc (having stood on the bridge at Stratford on Avon last week)

Janni Papakrivos - 2008/11/20 21:59:57 UTC

Fair is foul, and foul is fair.

Jim Rooney - 2008/11/20 22:25:38 UTC

Something to bear in mind... the tug's weaklink is three strand.
For clarity... A normal single loop weaklink would be considered two. A tandem double loop is considered four.
In the tandem setup, the "weaklink" in the system is at the tug end, not the glider.

Ya'll seem to be missing this.
Once you go beyond three strand... you're not using a weaklink. If the weaklink goes, you're getting the rope.
Paul found this out the hard way in Texas.

Theory's wonderful and all, but reality is not forgiving.
Ask yourself... are you willing to bet your life on your theory?
Dress accordingly.

Keep fighting Janni. He'll never listen to you, but it's entertaining to watch

Lauren Tjaden - 2008/11/20 22:50:53 UTC

Our weak links are not ideal, and I appreciate Tad's efforts to improve our towing safety. These efforts have also included the types of releases we use and their location.
I practiced releasing using varied types of release under load (on the ground) at Highland this year, and found it very educational. When pro-towing the method the pilot uses to release can be very important (something I'd never realized, since I've -- knock on wood - never locked out while pro-towing). I found that the only way to release under strong loads (with either curved or straight pin releases) was to grab the TOP of the barrel instead of just grasping around its sides.
But about the weak links.
My husband, Paul has suffered more weak link breaks than I have, which is certainly due to his weight. (At least that's his excuse. Heeheehee. Paul told me to put in this line.) I have broken one in the last two years, with LOTS of tows.
Tad gave Paul a couple of HIS links while we were at the ECCs this year. Paul used them happily ( without any situation that might cause a problem) until one day at Zapata in rough air while he was attempting to adjust his VG. Paul locked out badly and the link didn't break. The double weak-link attached to the tug plane BROKE because the forces were so extreme. Russell quoted afterward that he'd never had his tail pulled around so violently. Luckily, Paul's glider was not stressed to the point of failure, and Paul was able to drop the rope and landed safely.
My only point here is that Tad's releases have not been extensively tested, and at least in my experience with them, are not safe.
I just don't want pilots to think that his weak links are entirely the answer. Tad is very smart, and is trying to address the problems he sees, so he should get kudos for that. But be very careful before you buy into the "great-new-weak-link-thing."

Brian Vant-Hull - 2008/11/21 01:38:30 UTC

That's a very good point: maybe the purpose of the weak link is to set an upper limit on how much force the tug is willing to tolerate, which has nothing to do with the mass on the other end of the line. This would explain one size fits all.

Theory is only as good as the initial assumptions, and in this discussion all assumptions have been directed towards the glider end of the rope.

Janni Papakrivos - 2008/11/21 05:08:50 UTC

That's a very good point: maybe the purpose of the weak link is to set an upper limit on how much force the tug is willing to tolerate, which has nothing to do with the mass on the other end of the line. This would explain one size fits all.

Are you suggesting to use 2 tug weak links on both ends of the line? I think the purpose of the weak link is to be just strong enough so it won't break all the time. That's exactly what I have. It may and will not safe me from every lockout situation (especially where line tension is irrelevant), but if disintegration of my glider is the alternative I'll be very happy with it.

Theory is only as good as the initial assumptions, and in this discussion all assumptions have been directed towards the glider end of the rope.

Theory in this discussion has also been based on the assumption that every pilot always has time to get off tow before things get sour. Those who fail are

either incompetent or brain dead or, as is the usual such case, some combination of the two

. Thanks Tad. I had a lot of fun with you. Stay tuned for my lockout experiments using 0.5 G weak links next season.

Tad Eareckson - 2008/11/21 06:22:46 UTC

Janni,

I think there are dangers to increasing their strength and I think there are dangers to flying with understrength weak links as well. It all depends on what risks you're more comfortable taking.

The risk you're more comfortable taking is flying with a release that you cannot be sure will be accessible and may not work in an emergency. The safety margin you have already decided to discard is so wide it makes all discussion of weak link strength irrelevant.

What you mean here is staying on tow is always safer than landing (you don't climb in a lockout all that great), and that's nonsense as well.

No. I meant what I said. Climbing out is ALWAYS safer than landing.

And - yes - you can climb just fine in a lockout. Since you can't ask Rob Kells about this, try running it by John Dullahan.

Irrelevant, weak links don't create line tension.

I didn't say they created tension. What I'm trying to get you to understand is that if you need more tension than the weak link can transmit you don't get ANY tension. Do you understand that?

Perhaps I found the sweet spot?

With respect to what you're trying to do - which is dial in a strength which can make decisions for you and supersede the role of the release - THERE IS NO SUCH THING AS A SWEET SPOT.

Jim,

What results did you get for the two, three, and four strand weak link strength tests?

In the tandem setup, the "weaklink" in the system is at the tug end, not the glider.

So does the tandem glider always end up with the rope when a weak link pops?

Paul found this out the hard way in Texas.

Carlos found out you can get the rope locking out behind a Dragonfly with a two strander at his end. How do you explain this?

Ask yourself... are you willing to bet your life on your theory?

Janni's willing to bet his life on the theory that his weak link fail in time to keep him from slamming in. Is this a theory to which you also subscribe, despite all the fatality reports supporting another conclusion?

Lauren,

I practiced releasing using varied types of release under load (on the ground) at Highland this year, and found it very educational.

At the ECC in June I had my test rig configured to allow release actuation under loads up to 388 pounds. I recall Paul taking a spin but not you.

Lotsa other people checked things out and, whereas most had no trouble dumping max load (equivalent to 776 pounds of tow line tension) using only their thumbs and index fingers on my straight pin barrel release, most where unable to budge the curved pin Bailey without prolonged and/or repeated efforts under HALF (194 pounds) the load.

Mark Gregor - age seven late this summer - was also able to dump 388 pounds off the straight pin (albeit with more time and effort than I had hoped).

I found that the only way to release under strong loads (with either curved or straight pin releases) was to grab the TOP of the barrel instead of just grasping around its sides.

I think Brian can attest that you can blow one of my straight pins under twice the max load anyone's gonna experience in the air in your sleep no matter how you grasp the barrel (suitable for ages ten and up).

Tad gave Paul a couple of HIS links while we were at the ECCs this year.

Tad recommended and gave Paul a couple of Paul 1.4 G weak links which, to the best of my recollection, limited tow line tension to 420 pounds. Paul could have (and still can) requested weak links of any G rating he wanted.

Russell quoted afterward that he'd never had his tail pulled around so violently.

Russell determined the violence with which he was willing to have his tail pulled around when he selected the weak link strength for the front end.

Luckily, Paul's glider was not stressed to the point of failure...

Luck didn't have squat to do with it. Regardless of what was on the front end - which probably failed twenty pounds before the back would have - the glider was stressed to under three Gs (Paul's contribution plus the line tension immediately prior to weak link failure). Hang gliders are good for a minimum of twice that.

The weak link system did EXACTLY what it was supposed to.

The action was violent - It's supposed to be. It's not supposed to be the routine nonevent to which we've all grown so accustomed. He blew at 1.33 Gs. If Karen tows one point using a one size fits aller she blows at 1.40.

The weak link system is ONLY supposed to protect the planes. The planes were not damaged.

Note also that USHPA defines the upper weak link limit at 2.0 Gs. I gave Paul a 0.6 G / 180 pound margin. If I was out of line then USHPA is WAY out of line.

Paul got the rope 'cause the tug isn't allowing him to operate within established safety standards.

Tad's releases have not been extensively tested...

I don't know if you meant to say "releases" or "weak links". In any case... They HAVE - in fact - been VERY EXTENSIVELY tested. The summaries have been available online for the better part of a couple of years and the raw data will be provided upon request. Do you know of any other designs for which you can find such data?

...and at least in my experience with them, are not safe.

Based on what?

But be very careful before you buy into the "great-new-weak-link-thing."

If you're flying, you've already bought into something. And what virtually everyone has bought into was someone's unqualified say-so.

And with respect to weak links. What virtually everyone as bought into is a magical loop of Greenspot that EVERY solo pilot is told will put him or her at 1.0 Gs.

Brian,

As I've said before - THE TUG IS THERE TO ACCOMMODATE THE GLIDER. It needs - AT THE BARE MINIMUM - to be able to allow me to fly at a weak link rating as good as Karen's.

There is no more THEORY behind the way we've been doing weak links than there is behind using curved pins in barrel releases or mounting release actuators on downtubes. It's all STUPIDITY based.

Do me a favor...

Go back to:

http://www.questairforce.com/aero.html

Read what it says about solo weak links.

Think about it this time. Pretend you're a high school physics teacher evaluating a science project.

THAT'S WHY WE'RE DOING THINGS THE WAY WE ARE - NOT BECAUSE THERE'S INTELLIGENT LIFE ON THIS PLANET.

Janni,

Theory in this discussion has also been based on the assumption that every pilot always has time to get off tow before things get sour.

Your theory is based on the assumptions that:
- A weak link can be dialed in to prevent you from slamming in; and
- You will never be in a situation such as Danny was and in need of tension to pull you out of trouble.

Good luck.

Stay tuned for my lockout experiments using 0.5 G weak links next season.

This winter I'm gonna put a lot of effort into making the use of 0.5 G weak links non compliant with the USHPA SOPs and thus illegal under the terms of FAA Aero Tow Exemption #4144.

If I fail and the folks at Highland are dumb enough to let you pursue your Holy Grail I'll only be able to request that you don't gum up the works during the soaring windows any more that the riduculous extent to which they are now. Believe it or not - I like to have an opportunity to fly every once in a great while.

By the way - at 0.5 Gs you're not even gonna be able to get the cart rolling.

Jim Rooney - 2008/11/21 08:01:04 UTC

As I'm sure I'm referred to in Tad's post, I'd just like to remind our viewers that he's on my "foe" list and I'll neither be reading nor responding to his post.

Lauren Tjaden - 2008/11/21 12:38:21 UTC

Regarding Tad's last post: I spent at least half an hour on a quiet day before the ECC (I don't think Tad was there)testing releases under load. What I found personally was the straight pin was a little easier than the curved, but it was not really easy. I was shocked at hard both were. I frankly thought it was great training, because to figure out how to get those things to release under pressure might have taken several lifetimes (literally) to figure out in the air. (When I closed my hand over the top of the barrel they would release. I never even realized before that my habit was to just grab the sides of the barrel.)
The weak link Tad gave Paul did not break under pressure that was so violent that it broke the TUG'S weak link. It was a pretty scary incident. (Sometimes regular weak links do not break when they should, either. However, the very first time this particular link should have broken it failed to do so. And yes, when the glider yanks the plane sideways, the link should break. Never did.)
There are also certainly cases where a link breaking early can be dangerous, and it is always a hassle. For heavier pilots on big gliders the standard weak links are a little light. But make no mistake that being stuck to the plane is something that can also be fatal.
When making your choice about this, remember that the tow park has a say in it. Many will not allow you to use anything other than a standard weak link. At many meets your link is checked before you are allowed to launch. Pilots sometimes beef up their links in order to avoid having to relaunch, with sometimes tragic results.
BTW, the tandem at Quest certainly has a weak link on the glider side. As far as I know, all of them do.
Again, Tad is smart, and no one can accuse him of being apathetic. His desire to improve safety should be applauded. However, these are simply my personal experiences.

Gary Devan - 2008/11/21 14:57:43 UTC

my dearest tad,
over the course of our online affair we've experienced many ups and downs, consistent with any passionate relationship.
albeit with a few lapses, it's apparent that you've been attempting to live clean and sober and you must certainly see that the results have been beneficial to both you, your cause and those who so desperately have attempted to be a part of your life, a part of your quest.
people obviously are feeling safer about approaching you, particularly when in disagreement.
so if i can offer you these words of encouragement at this critical juncture - don't fricking blow it now! keep on keepin on.
love and kisses,
gary D

Gary Devan - 2008/11/21 15:50:44 UTC

oh yeah, best if read with the voice of Barry White (deep soulful bass r&b singer) in mind.

Janni Papakrivos - 2008/11/21 16:56:55 UTC

I didn't say they created tension. What I'm trying to get you to understand is that if you need more tension than the weak link can transmit you don't get ANY tension. Do you understand that?

You are right. My mistake. FYI, I never had any problems catching up to the tug when I got too low and slow using understrength weak links.

And - yes - you can climb just fine in a lockout.

As did the guy in the video and as did Paul when he almost stretched the sail of his $10,000 glider to the point where he'd have to consider competing with Falcon pilots.

the glider was stressed to under three Gs (Paul's contribution plus the line tension immediately prior to weak link failure). Hang gliders are good for a minimum of twice that.

...and belong in the trash after that

This winter I'm gonna put a lot of effort into making the use of 0.5 G weak links non compliant with the USHPA SOPs and thus illegal under the terms of FAA Aero Tow Exemption #4144.

Thanks. I'm looking forward to collaborating with you.

Tad Eareckson - 2008/11/22 10:17:33 UTC

Janni,

FYI, I never had any problems catching up to the tug when I got too low and slow using understrength weak links.

If you have ever had a weak link - understrength by definition - pop for no other apparent reason - as I'm rather certain you have - then it doesn't matter whether or not you've had one break in a potentially dangerous situation. You are vulnerable and operating in dice roll mode (which seems to be your style of choice anyway).

As did the guy in the video...

The guy in the video was NOT climbing in a lockout. The guy in the video decided he wanted to get as good a view as possible in as short a time as possible. Upon attaining that goal his remaining options were to go straight down or down with one of two sidewise options. Since the guy was obviously not a control freak he allowed the decision to be made for him.

Have you noticed that you seem to be the only person on the planet who considers this near fatality to be a weak link issue?

This - of course - would be consistent with your inability to recognize that you had a problem in your own near fatal situation which resulted from your own total failure to control the glider in totally benign conditions.

You, Tog, and MG oughta get together for a few beers and some "There I was!" stories. I'm sure the three of you will be able to keep each other entertained for about 36 hours non stop. And you haven't even commenced your 0.5 G experiments yet

...and as did Paul when he almost stretched the sail of his $10,000 glider to the point where he'd have to consider competing with Falcon pilots.

Bullshit. You seem to have a problem discarding data inconvenient to your hypothesis and inventing it when it suits you.

...and belong in the trash after that

Also bullshit. And of what relevance in any case?

How 'bout an alternative approach...
- Learn to recognize and understand what the genuine experts in this field are saying before you challenge it and experiment with square wheels.
- Learn to recognize incompetence as you observe and commit it.
- Bring your equipment up to minimal standards.
- Learn to fly.
- Adhere to the above order.

Brian,

Brian Vant-Hull - 2008/11/10 03:03:29 UTC

The blanket statement that weak links do nothing to protect the pilot may not be strictly correct, just mostly true.

Brian Vant-Hull - 2008/11/14 21:04:07 UTC

We lighter pilots have been towing with proportionally stronger links for years, and I think we've been happier.

Brian Vant-Hull - 2008/11/20 13:16:41 UTC

Yes, there are dangers to increasing the weak length strength, but since I'm concentrating so hard when near the ground and I have my finger literally on the release, I can deal with it faster than the link can.

You keep pinging in real close to the target but you're not hitting it and you NEVER will as long as you're thinking of a weak link as having anything to do with the safety of the PILOT.

I'm gonna skip the quotes this time but... Freeman, Kroop, Caruk, Hewett, Danny...

Within the limit of 2.0 - THERE ARE NO DANGERS TO INCREASING THE WEAK LENGTH STRENGTH.

The weak link is there to keep the glider from breaking and YOU CAN'T BREAK A GLIDER WITH A 2.0 G WEAK LINK.

It's only when you start compromising on the definition of a weak link and try to use it as compensation for an unqualified pilot do you start making it dangerous.

Janni was allowed to slip through the cracks. He had no business being on the end of a tow line by himself at his skill level and NOBODY has any business getting on a cart with a release such as that.

His weak link broke and he lucked out. If he does the same thing a second time is weak link will break and he'll luck out. The third time he does it he's gonna get killed.

You put enough people in the air you're gonna kill some of them. If you gotta kill folk you wanna kill the ones who aren't doing their jobs. You don't wanna kill the ones who were doing everything right.

If you try to dumb the weak link down to allow Janni to survive two extra flights he shouldn't have - then you kill Bob by robbing him of the ability to exercise control of his situation. And if you do that you've subverted the course of Darwinian evolution.

Let's remove the K2 fiasco from the equation and assume that you've had an unneeded/undesired weak link break at some other point in your flying career. That being the case - you got killed (as I indicated Janni).

You put yourself in the low level Bob oscillation (or Danny tip stalled) scenario, that weak link WILL pop at the WORST POSSIBLE instant, and you WILL cartwheel.

And your last thoughts will be...

"HOW COULD I HAVE BEEN SO -STUPID-! I never needed a weak link in the first place 'cause I was a halfway competent tow pilot, I had a good release, and I was never in a situation in which I couldn't beat the weak link if necessary. If only I had been able to hold onto the tow it would have pulled me out of trouble and I'da been fine."

THAT'S why I fly 1.4 and that's why - if I'm ever in such a situation and something on the other end of the line pops or is released - my last thoughts will NOT be kind ones.

Tad Eareckson - 2008/11/22 10:23:21 UTC

Oops. Clicked "Submit" by mistake.
Add a period and make that "indicated to..."

Tad Eareckson - 2008/11/22 16:38:56 UTC

Jim Rooney:

2008/11/20 22:25:38 UTC

Keep fighting Janni. He'll never listen to you, but it's entertaining to watch

2008/11/21 08:01:04 UTC

As I'm sure I'm referred to in Tad's post, I'd just like to remind our viewers that he's on my "foe" list and I'll neither be reading nor responding to his post.

Ya gotta love the irony.

Brian Vant-Hull - 2008/11/22 19:27:02 UTC

Tad -

You keep saying there's been 40,000 incident free tows at Ridgely, then turn around and say the present weak link system will kill people. Obviously you don't value consistency or you wouldn't be trying to change things.

Jim Rooney - 2008/11/22 22:31:35 UTC

Nail on the head Brian!

The simple fact is this. The only reason anyone even gives Tad the time of day is that they want to believe him. Why? Because they don't like to be inconvenienced by a weaklink break. That's it.

Sure, everyone digs around for other reasons to believe, but at the heart of it, it's convenience.
No one is actually scared to fly with a standard weaklink. They may say they are, but deep down inside, they're not. BTW, this weaklink as a lifeline comment... any tow pilot that takes you over something you can't get out from should be shot. It is one of the cardinal rules of towing. Again, "I wana believe" rationalization.

Tad loves to speak of himself as a scientifically minded person. Yet he ignores a data pool that is at minimum three orders of magnitude higher than his. It is thus that I ignore him.

Gary Devan - 2008/11/23 01:37:16 UTC

i'm pretty sure about the veracity of this, i could be wrong (could have used veracity inappropriately as well but hey, screw it). does anyone remember when all the best scientific minds with all the then current scientific theories and engineering info and studies and all that stuff . . . remember when science was pretty much certain that bumble bees couldn't fly? damned things kept on flying anyhow. i'm just saying.
garyD

could be that was one of them urban science myths and i've been out of the lab for a long time.

Gary Devan - 2008/11/23 03:48:43 UTC

jheez what was i thinking. i left my password and stuff out where my dog found it. i'm on the other line right now with purina and my credit card company. so uhm how 'bout we just say that post never happened (you know, like always).
garyD

damn dog, always getting me in trouble. used to eat my homework too.

Brian Vant-Hull - 2008/11/23 05:00:43 UTC

I think Tad has a point that we could perhaps scale up the links for heavier pilots, and convenience keeps us from doing so.

But there's perhaps an upper limit for situations not well described by theory, and I get annoyed when someone professes to know the entire truth and everyone else must be idiots. (Okay, I may have once said Bernoulli's principle has nothing to do with wings, but I was willing to modify that to say it's not a simple connection and you're better off without it for normal discussion and quick calculation. And I never intentionally insulted anyone's intelligence the way Tad continues to.) I think he's largely right, but I'll back down and modify when presented with new evidence.

Right now I'm still digesting the idea that the tug doesn't want to be yanked in strange directions by more force than a standard weak link will allow. The link on the tug end may be there to protect tug equipment from breaking during a bridle wrap, the one on the glider end may be there to prevent the tug from nosing into the ground. The poor tug has to watch everything in a 4 inch mirror, for pete's sake.

It's good to discuss and make sure we know exactly why things are there, but I'd really like to see a little less god complex from a certain someone.

Janni Papakrivos - 2008/11/23 05:28:41 UTC

What I don't get is why even bother using Tad's weak links? They don't break, they yank the tug around, why not omit them and hook to the tow line directly? If you don't get off tow in time you're an idiot anyway, and the tug's weak link is going to safe the tug and, hopefully, your glider. What's the point?

David Churchill - 2008/11/23 07:36:09 UTC

Maybe the point of weak links is for people that aren't as smart as Tad and would be trying to "save" the tow when they should be releasing. Also if it gets bad enough that you'd end up breaking the tug's connection you're probably be better off breaking the glider link so you don't have to deal with the tow cable.

If we all learned when to release, and when not to, maybe we could do away with weak links altogether.

OFF TOPIC: was there a definitive answer to Kirk's question?

Jim Rooney - 2008/11/23 08:50:52 UTC

If we all learned when to release, and when not to, maybe we could do away with weak links altogether.

Oh if only life were so simple.
How's it go?... that's right... Sh1t Happens.

That's what weaklinks are all about. There for that "OH SH1T" moment.
You can ponder all you like the way this or that should happen and what you should do in such a moment. But the plain fact is that when it all goes to custard, things tend to happen really fast.

Now I'm of the variety that likes to stack the deck in my favor. I like to have things that might help me out when it's all going to hell. I most certainly do not want things that don't help involved. I don't need to rely on these things to appreciate that they're there.

BTW, all this talk about "the only reason for a weaklink is to protect the glider" stuff is absolute piss. Sorry, that's a reason for weaklink. This notion that it's the only reason is nothing short of dangerous.

A weaklink's purpose is to improve your safety.
Plane and simple. The rest is how it does it.

Not having the glider fold up does help your odds of survival. So does inconveniencing you by letting go of the rope for you... whether you like it or not.

I'm sure Tad will happily write a 20 page dissertation on everything I've said here. Have fun. I don't read posts from him. If anyone else cares to discuss any of this, I'm happy to do so. You might have to pm me to get my attention as the weather here is often far more conducive to flying.

Fly safe guys.

Brian Vant-Hull - 2008/11/23 13:48:33 UTC

hey Jim;

If the weak link is to protect the pilot from certain aerobatic manuevers, then it should scale with pilot mass, plain and simple. But that's not the only consideration.

A fixed strength (if logically justified) must have something to do with the tug. I think the glider end link should scale with pilot mass up to the point where the tug doesn't want to deal with being jerked around so much. Another upper limit is the weak link on the tug. If above a certain strength it begins breaking things on the tug, then the glider weak link must be weaker than this.

So two upper limits, one for the Tug, one for the glider. Scale the link strength with tow mass up to the glider link maximum, though where that is can be debated. I don't believe like Tad that the FAA necessarily is the last word, and his 1.4 G links may be too strong, especially for heavier pilots who will just have to deal with more weak link breaks. But I think strengthening them somewhat for heavier pilots makes perfect sense.

What, did Kirk have a question?

Janni Papakrivos - 2008/11/23 14:17:39 UTC

BTW, all this talk about "the only reason for a weaklink is to protect the glider" stuff is absolute piss.

A weaklink's purpose is to improve your safety.

Hahahahahahahahahaha.

Tad Eareckson - 2008/11/23 17:12:27 UTC

Brian,

Brian Vant-Hull - 2008/11/22 19:27:02 UTC

You keep saying there's been 40,000 incident free tows at Ridgely, then turn around and say the present weak link system will kill people. Obviously you don't value consistency or you wouldn't be trying to change things.

There have been 40 K launches at Ridgely in which - to my knowledge - no one has suffered an injury worse than a skinned knee.

There have no freakin' way been 40 K incident free tows.

An incident free tow is one in which you get on the cart and release after getting where you wanna go.

If you continue on your merry way after Zach waves his left arm that's an incident free tow. Ditto if at 1100 feet you notice that he's corkscrewing as tightly as possible, your vario's pegged, and you say "GOOD ENOUGH".

Nothing else qualifies as an incident free tow.

Examples of incidents - engine failure, tug runs out of gas, at any altitude glider is forced to release because it gets kicked too hard to recover, at any altitude glider is forced to release because pilot kicks it too hard to recover, glider fails to preflight harness and dolly is carried aloft at the end of a pod lanyard, any release - primary, secondary, or tug - fails at any time - (whether or not it the tug is stalled as a consequence), a weak link break at ANY point for ANY reason - legitimate or not.

An incident is also an accident if the glider gets a skinned knee or folds a seventy-five dollar downtube in half.

The launch injury rate at Ridgely is negligible enough that we can call it zero for the time being.

The launch accident rate ain't so good - based on my tiny sample of first hand observations.

The launch/tow incident rate totally SUCKS.

Now gimme a moment to rewind the tape...

Normally the one size fits all weak link results in no more damage than keeping prices high, degrading everybody's flying experience, and denying folk access to the soaring window.

However, once in a 40 K launch cycle a no fault situation arises in which the glider pilot's life is totally dependent upon the tow line. THAT'S why anybody who starts dipping significantly below 1.4 is asking for trouble, the FAA does not permit sailplanes to fly below 0.8, and people like Janni need to be protected from themselves.

But there's perhaps an upper limit for situations not well described by theory, and I get annoyed when someone professes to know the entire truth and everyone else must be idiots.

As long as you keep thinking of the weak link as an alternate release in place to protect the pilot you're NEVER gonna get this.

As I've said many times before... It took me two years to accept what James Freeman:

http://www.dynamicflight.com.au/WeakLinks.html

and a few others amongst the best minds were saying. The logic is unassailable and the data backs it up. When it finally sinks in you get this electrifying E=MCsquared sensation. I hope it will come to you sometime - it's totally awesome. Nerd Nirvana.

Right now I'm still digesting the idea that the tug doesn't want to be yanked in strange directions by more force than a standard weak link will allow. The link on the tug end may be there to protect tug equipment from breaking during a bridle wrap, the one on the glider end may be there to prevent the tug from nosing into the ground.

We need to kill this crap right now.

Think about it.

Karen - as is: two point, one size fits all.

The weak link limits her (or - for that matter - me, so configured) to 243 pounds of tow line tension.

Assuming nobody squeezes a lever the most damage that Karen can do is to use that 243 pounds to pull perpendicular to the longitudinal axis of the Dragonfly - straight up, straight down, straight left, straight right, or straight any hour on the clock you wanna name.

Let's suit me up in my flying gear. That puts me DAMN close to 243.

I start off in the transporter bay of the Enterprise. Zach is up at a thousand feet for a morning conditions check with nothing in tow.

I say, "Scottie, beam me down to the coordinates of Zach's tail wheel, leave me there for five seconds, then beam me back (without fail)."

What the fuck do you think is gonna happen to that tug with me dangling from the extreme aft end?

THAT'S what Karen can do to the Dragonfly. 'Cept she can do it in any direction she wants. The weak link will allow her - given the time - to dwarf to insignificance the effect that Paul had on Russell.

NEITHER THE FRONT OR BACK WEAK LINK CAN ENSURE THAT EITHER AIRCRAFT REMAINS IN CONTROL.

Ralph's 2000/08/26 RELEASE FAILURE incident should have convinced you of that FACT over eight years ago. Paul just jerked the tail around - Ralph STALLED AND DROPPED the tug.

http://groups.yahoo.com/group/skysailingtowing/message/4597
RE: [Tow] Weaklinks

Donnell Hewett - 2005/02/08 23:28:31 UTC
Department of Physics
Texas A&M University-Kingsville
MSC 175 Kingsville TX 78363-8202

It is impossible to design a weaklink to release the pilot when he loses flight control because there is no correlation between towline tension and flight control.

Jim Rooney - 2008/11/20 22:25:38 UTC

Something to bear in mind... the tug's weaklink is three strand.

In the tandem setup, the "weaklink" in the system is at the tug end, not the glider.

So - if this is indeed the case - the tandem's weak link is irrelevant - as is Paul's. So how can towing Paul with a 1.4 G weak link have any more bearing on how violently the tug's tail can be jerked around than towing the tandem?

Jim Rooney - 2008/11/22 22:31:35 UTC

No one is actually scared to fly with a standard weaklink. They may say they are, but deep down inside, they're not.

I have never launched with a release actuator farther away than four inches inboard of the port end of the basetube. At that range I was scared towing.

After experiencing a real exciting lockout seven and a half years ago I decided the range was - indeed - WAY too far and shortly thereafter engineered what today remains the best means of firing a two point release anywhere.

After that the only three things I was scared of were a bridle wrap, the problem of actuating a secondary / one point release, and a weak link break. Steve figured how to neutralize the middle one, I engineered out the other two.

The weak link problem was the last to fall - two seasons ago.

Jim Rooney does not speak for Danny and me. And anybody who believes there is such a thing as a "standard" weak link is clueless (against my better judgment I restrained myself from using the term "idiot"). And anybody who isn't scared of using a weak link anywhere south of about 1.2 is living in blissful ignorance.

I was ALWAYS scared of the "STANDARD" weak link. I was always scared it was gonna fuck up my day - and it often did (and if you count other people's "standard" weak links - it almost always did) and because it could - and often did - commit me to a forced landing.

My regular landings are the scariest part of my flying day - I don't need to do more of them.

Jim Rooney - 2008/11/22 22:31:35 UTC

BTW, this weaklink as a lifeline comment... any tow pilot that takes you over something you can't get out from should be shot.

This little snippet is pretty good evidence that Jim's foe blocker doesn't work very reliably.

This is an apparent reference to the letter of Donnell Hewett's which I cross posted here.

In the post immediately following this one I will cross-post my response to him so everyone can see read MY position on the issue. Scroll on down to "Releasing low over unsuitable terrain...".

Brian Vant-Hull - 2008/11/23 13:48:33 UTC

I don't believe like Tad that the FAA necessarily is the last word, and his 1.4 G links may be too strong, especially for heavier pilots who will just have to deal with more weak link breaks.

Brian Vant-Hull - 2008/11/11 21:55:59 UTC

Well....

if it just happens to break when you are partially in a low to the ground wingover, it kinda sucks. As Tad says, the tug's pulling you away from the ground, so in many cases you're better off staying with it until you choose your moment to release. They tend to break when stuff is already bad, not before it gets bad.

If heavier pilots will just have to deal with more weak link breaks then they are not being allowed to fly with the safety margin afforded to lighter pilots.

THIS IS NOT HOW YOU RUN AN AIRLINE!

If there is any good evidence that the Dragonfly cannot safely withstand the 450 to 500 pound tow line tension which would keep all the big solos happy and ensure that the tug leaves with the rope - I have yet to see or hear of it.

Janni Papakrivos - 2008/11/23 05:28:41 UTC

What I don't get is why even bother using Tad's weak links? They don't break, they yank the tug around, why not omit them and hook to the tow line directly? If you don't get off tow in time you're an idiot anyway, and the tug's weak link is going to safe the tug and, hopefully, your glider. What's the point?

The point of having a weak link is that - even if everything else gets fucked up beyond all recognition - you'll be left with two intact planes with which people can fly away PROVIDED they have enough altitude with which to recover. NOTHING MORE - NOTHING LESS.

David Churchill - 2008/11/23 07:36:09 UTC

If we all learned when to release, and when not to, maybe we could do away with weak links altogether.

David,

Prior to your attainment of an AT signoff you must not be put into a situation in which release timing is critical.

Upon attainment of the rating... YOU ARE -REQUIRED- TO KNOW WHEN TO RELEASE.

OFF TOPIC: was there a definitive answer to Kirk's question?

Yeah. Fulfill the requirements of your rating, use the best release configuration available, and use a weak link in the middle of the safety range - 1.4 Gs - and don't try to get it to do jobs of which it is not capable.

Tad Eareckson - 2008/11/23 17:15:54 UTC

http://groups.yahoo.com/group/skysailingtowing/message/6745
Weaklinks

Tad Eareckson - 2008/11/06 16:13:36 UTC

Donnell,

While I still maintain a couple of minor points of disagreement - CLOSE ENOUGH! Can I get a framed, autographed copy of that post on acid free paper?

http://groups.yahoo.com/group/skysailingtowing/message/6744
Weaklinks

Donnell Hewett - 2008/11/05 21:22:29 UTC

I believe everyone recognizes that "one size weak link simply does not fit all".

I wish.

Over the course of the past couple of seasons I've been able to batter my local crowd down enough to get a few 1.4 jobs in the air but at the flight line if a 320 pound skygod glider asks for a weak link he gets the same loop of 130 pound Greenspot as a 200 pound first time soloer.

If the big guy puts the link on the end of his two point bridle he has about 0.76 MAX and practically something that is very likely to break at 0.4.

If the new chick puts it on her two point, she has a solid 1.22. After she gets better and starts towing off of her shoulders she gets 1.4.

http://ozreport.com/12.81
Weaklinks - the HGFA rules

Davis Straub - 2008/04/22 14:47:00 UTC

Here is the requirement from the 2007 Worlds local rules (which I wrote) for weaklinks:

Weaklinks

Pilots must use weaklinks provided by the meet organizers and in a manner approved by the meet organizers. All weaklinks will be checked and use of inappropriate weaklinks will require the pilot to go to the end of the launch line to change the weaklink.

Weaklinks will consist of a single loop of Cortland 130 lb Greenspot braided Dacron Tolling line and should be placed at one end of a shoulder bridle.

Yeah, why consider glider weight at all. Next...

We need to codify a lower limit to give people a tool with which to protect themselves from kind of crap - which, by the way, is very much alive and well in the US too.

Personally, I am not convinced that all hang glider pilots are qualified to recover safely from such extreme aerobatic attitudes.

They may or may not be but - again - even a 0.8 (or less) G weak link may be of no use whatsoever in preventing an aerobatics champ from doing a steep wingover into terra firma. He can easily find himself in a situation in which his release is his only option.

That is why I still recommend a 1-gee maximum weak link when towing horizontally with a good tension controlled system.

Fine. Peter seems to think that 0.8 presents no problem. I yield the floor to the winch crowd. From what I understand of tension controlled towing I would imagine that you'd REALLY want to be off tow if the tension climbed that much.

In fact, I am sure you can imagine more than one situation where getting off line is the worst possible alternative you can take.

YEAH...

Danny Brotto - 2008/11/04 12:49:44 UTC

An instance where the weak link could have broken and I'm glad it didn't...

I had the Axis on the cart with the AOA a bit high, launching to the west, with a moderate 90 degree cross from the left. I came out of the cart rolled and yawed to the right with the upwind wing flying and the downwind wing stalled. It was rather dramatic. If I had released or if the weak link had broken, the downwind wing would have further stalled and I would have cartwheeled into terra firma in an unpleasant fashion. I held on tight gaining airspeed until the downwind wing began flying, got in behind the tug, and continued the flight.

Sunny later told be he was about to give me the rope and I thanked him to no end that he didn't. Lesson learned, check AOA on the cart especially in crosswinds.
---
An instance where the weak link held and it would have been nice if it had yielded...

On another instance, I was towing behind a trike being piloted by Bill Bennett as part of a demo at Fairfield (my sailplane port.) These were the early "experimental" days of aerotow. We were using a center-of-mass tow system, a three-ring circus release, and a fairly short rope. Bill commenced the tow, I came off the cart, and Bill started a rapid climb. This put me below the trike, stalled, and soon into the prop wash and tug wing-vortices. My Axis began to roll to the right, I tried to release but the polypro towline had some slack and the release mechanism held tightly. The line then tightened. I do not remember what kind of weak link was being used but with the mounting pressure I thought for sure it would break; but it didn't. I was rolling past 90 and gave the release one last yank. It released, I completed a wing over just over the tree line, and came in for a nice landing. Bill and I debriefed about the pull-up. The subsequent tow, without the rapid climb out, went okay.

Lessons learned, abandon the three-ring circus and use a decent release (I purchased the then "new-fangled" Wallaby Release) and you can't count on the weak link to get you out of an emergency situation.

Releasing low over unsuitable terrain is an obvious example of this exception.

I think most Dragonflies tow out of airports or more than adequate flight parks and they climb so well that terrain is not an issue 'cause if you pop off early you have - almost by definition - either enough remaining runway ahead of you or enough altitude to turn around and land normally.

In theory the worst thing that could happen to you would be to come down into propwash but I haven't heard of any good examples of this being a serious issue. I got some more info on the Texas Open case I referenced earlier and it seems that this bending occurred as a result of a pilot who was in no way qualified to aerotow getting on the cart.

But the first incident related by Danny - and another very similar recent one at Ridgely triggered by a dust devil - is the reason why I feel no one can safely aerotow below 0.8 Gs.

Danny doesn't weigh anything. If he did he'd have been flying the same loop of Greenspot and thus at a lower G rating and the probability of that thing popping at precisely the wrong moment would have gone WAY up.

The nice thing about dolly launching behind tugs is that you can release without moving your hand, in the case of two point - significantly or, one - at all.

I've developed an excellent AT release system in which I have total confidence. The pictures are up at:

http://www.flickr.com/photos/aerotowrelease/

and I'm helping a friend refine his really nice slap-on concept. I hope to have photos of it up in a few days.

The better your release system the less you think about the weak link as something that's gonna keep you out of trouble.

I can't thank you enough for the time and thought you put into these posts and for your comments regarding my efforts. I think they'll be most valuable in helping to get us to clean up our act. Definitely worth waiting for.

Jim Rooney - 2008/11/23 19:42:44 UTC

Brian... yep... the issue of the tug's link is a big one and you've summed it up nicely.
The tug uses 3 strand and so all this talk about using a stronger one is academic.
You don't get to have one that's equal or stronger.

Here's the other thing missing from this conversation, and it's not a quick soundbite one.
There is more to the bar than simply strength.
See we've got a system that has an extremely solid track record. It's a high bar and you can't improve one aspect at the expense of an other. (you don't get to lower my safety margins for any reason)

The first one we've finally covered is the tug's link. Here's some others...

Greenspun get's used because it's manufactured. It's a common and standard material. You can get it at a fishing store and everyone knows what it is. This seems trivial, but it's again one of those things that looks small, but isn't.

Argue all you like about the validity of it's consistency in manufacturing (I know Tad will), but here's the rub... it has a testing system in place. And it far exceeds anything any non manufactured article could hope to achieve.

I know when you hook up what you've got. It's assumed that you know what it is, so what? I want to know. Why? Cuz I'm on the other end of the damn rope! You don't get to make decisions about MY safety. You don't get to make decisions about how far I'm taking you into harms way. It's just not your call.

With greenspun, I know what you've got. We don't have to have a conversation about if I'm willing to tow you or not. If you roll up with something else, that conversation happens. I might decide that I'm willing to tow you, but that conversation happens. You are not the only one involved here.

So if you want to use something that "scales with weight", you need to find a common and quality controlled manufactured material that displays what it is.

Why?
You're asking a tow pilot to pull you.
You're asking someone else to join you in a dangerous environment.
You don't get to make decisions for me.

Gary Devan - 2008/11/23 19:48:35 UTC

tad,
not meaning to be flip, patronizing or anything like belittling or insulting or nothing - but that was a whole lot like relaxing to read. almost wish i was up to speed on the subject so i also could enjoy arguing(used in the dictionary sense) with you. because i too like a good argument. but alas i have no dog in this hunt . . .
now if anybody gets nasty like - well it's on them isn't it.
of course they can still tell you that you don't know where of you speak. but then that's the way it's supposed to go - a wrastlin' match with no eye gouging or ear biting. but if someone pulls someone else's hair i think the general rule is that that someone is still not allowed to kick them in the gonads.
it's a tough job being extraneous but i work damn hard at it.

Brian Vant-Hull - 2008/11/23 22:08:33 UTC

Jim, your point that a completely known and reliably tested weak link is the only 100% believable argument for one size fits all that I've heard. Of course, once somebody's been towing with it for a few months that's not really true anymore, but a tug pilot can always insist the link is replaced every 10 tows or something.

I can understand not trusting a hand made weaklink, no matter how much the creator fulminates about testing.

Is there perhaps a weaker material that is equally well known and tested, so people can make multiple loops with finer gradations? May be the only way to satisfy everyone.

Jim Rooney - 2008/11/23 22:28:30 UTC

If you can find one, more power to you.

Just keep in mind if you do, you need to be weaker than the tug's link... not equal to. You will need to talk it over with any tug pilot that you tow behind. Anything less is unethical. And just as you have the right to refuse a tow from any tugger, they have the right to refuse to tow you... for any reason what so ever.

Tad Eareckson - 2008/11/24 00:51:28 UTC

Hi Gary,

Appreciate the occasional words of encouragement but don't get your expectations of me up too high. I'm afraid I really enjoy every now and then kicking a gonad through the uprights from the fifteen yard line with a strong wind at my back when some more than deserving asshole is standing right in front of me with his legs spread. And I think it often serves a useful purpose.

P.S. I've had a soft spot in my heart for Barry White ever since, a few years before his death, he helped Lisa Simpson take a shot at a thinly disguised mob of pig fucking Texas rattlesnake rounduppers. (Yeah, I'm always hoping a big Diamondback gets an easy shot at a carotid artery.)

P.P.S. Postal time again... Forgive me.

Brian,

HAVE YOU LOST YOUR FREAKING MIND?! ARE YOU INHALING THE SAME MERCURY VAPORS THAT JIM IS? IS ANY SHRED OF REMAINING LOGIC TOAST? HAVE YOU HEARD A WORD I'VE SAID?

Jim Rooney - 2008/11/23 19:42:44 UTC

The tug uses 3 strand and so all this talk about using a stronger one is academic.
...
I want to know. Why? Cuz I'm on the other end of the damn rope!

Is it possible you do not see the INSANE DISCONNECT between those two statements?

You're asking a tow pilot to pull you.

I don't ASK the goddam tug pilot to tow me. I PAY the goddam tug pilot's employers to have him tow me.

USHPA - and the FAA - say I'm safe at 2.0 Gs. I don't want some one-size-fits-all idiot telling me I have to tow BELOW what the FAA is safe. Fuckin' string puts me at 0.76 Gs at best and 0.39 at worst.

It's none of the tug pilot's goddam business what I put on my end. USHPA says if I go 1.4 he's supposed to go heavier. If he doesn't, the effective weak link rating is entirely of his choosing. If it's something reasonable it doesn't really matter 'cause neither weak link will ever break with halfway competent pilots on both ends anyway.

If at any time either party doesn't like what's going on at either end of the rope there's a real simple solution to the problem.

Greenspun get's used because it's manufactured.

As opposed to being spun by elves in a hollow tree? (Duh.) By the way - this Sacred Standard that Jim has been using every day of his life for the past five years is actually GreenSPOT - but one would have had to have actually looked at the label to know that.

...You can get it at a fishing store and everyone knows what it is.

Bullshit. Most everyone thinks that Greenspot weak links are about twice as strong as they actually are (which is the root of most of our problems). It's a real good bet Jim has never tested one in his life and thus suffers under the same delusion.

Argue all you like about the validity of it's consistency in manufacturing (I know Tad will), but here's the rub... it has a testing system in place. And it far exceeds anything any non manufactured article could hope to achieve.

No, he doesn't know Tad will. Tad doesn't give a rat's ass about consistency in manufacturing 'cause it isn't so much as a speck on the radar compared to the degradation a weak link undergoes at the launch of a medium to large glider. That's why a virgin weak link that - in theory - will blow under 243 pounds of tow line tension FREQUENTLY gives up the ghost at 125. (Consistency my ass.) And what "testing system"?

Is there perhaps a weaker material that is equally well known and tested, so people can make multiple loops with finer gradations? May be the only way to satisfy everyone.

Yeah Brian. I did that THREE YEARS AGO. The folk who have switched to my configuration include Christy Huddle, Tim Hinkel, Hugh McElrath, Rich Cizauskas, Sunny Venesky, and Campbell Bowen. Steve Kinsley is flying a double loop so I get partial credit for him. Yeah, not much quantity yet but quality oughta count for something.

Janni Papakrivos - 2008/11/24 01:20:25 UTC

Gee Tad, Jim is just making sure nobody is going to rip off the tug's tail above Highland, they are kind of expensive, you know.
Brian, I don't know why you feel us bigger guys need to beef things up. Talked to Glen, he gave me permission to drop his name. He hooks to the tow line at an impressive 350 lb. He had a total of 1(!) unexpected weak link break out of all his tows. He knows nothing of this discussion, so I asked him how he felt about using a stronger weak link. His answer was a straight "NO". Both Glen and I veto you on beefing our weak links up based on our good and safe experience with greenspot.

Gary Devan - 2008/11/24 03:23:02 UTC

"HAVE YOU LOST YOUR FREAKING MIND?! ARE YOU INHALING THE SAME MERCURY VAPORS THAT JIM IS? IS ANY SHRED OF REMAINING LOGIC TOAST? HAVE YOU HEARD A WORD I'VE SAID? "

that part actually had a sense of "you said wHat!? " about it.

beyond that you went back to being, well pretty much what most everyone has concluded, including having a somewhat pathetic and obvious perverse pleasure in being perverse. but it's not even creatively perverse. it actually Does get boring after a while, a predictable and unimaginative shtick. i suppose that's why some people are able to look past it. me? it's just gotten old. actually it got old any number of years ago. it ain''t worth the time and i went through all this some time ago over on the general forum . but that was at least entertaining. see ya and have at it.

Brian Vant-Hull - 2008/11/24 03:35:02 UTC

Janni;

I'm not 100% sure I can speak for all us lighter pilots, but I suspect if anyone asked us to use a weaker link for safety's sake, we'd raise an equal or bigger stink.

Glen's experience of rarely breaking a link seems to jibe with the idea (garnered from my old K2 versus falcon) that if you are on an easier glider you just ain't likely to break a link, and it's more important than mass. Whatever. I've grown weary of this whole thing. Tow with what the tug pilot is willing to let you get away with if it makes you comfortable. All we've done is put some ideas out there.

Tad - please stop acting like everyone has to conform to your version of absolute truth. The tug pilot has to feel comfortable, and if he insists you have to fly with a magic rabbit foot you better go out and get yourself one.
And yes, since the tug's ass is on the line he's got every right to veto who he tows. May eventually get fired if exercised too often, but that's his own business and right. 'Inalienable right' and 'physically correct' need not be correlated.

Black folks in a bad neighborhood don't like that they can't get a cab at 3 am, but nobody's gonna write a law saying the cabs have no right of refusal. Safety always takes precedence over provision of service, and individuals have every right to decide what personal steps they take to keep themselves safe. You can do your best to convince them they are wrong, but it's ultimately their own perception that counts. Maybe if you accept this you'll stop going postal and take the more patient and productive route.

Gary Devan - 2008/11/24 04:09:57 UTC

and i should have added that it's doubtful that that victim shtick will play the next go around. given a clear field of play, a clear unmuddy field of view for the rest of us, some slack, some rope as it were, and you chose to hang yourself while at the same time revealing some things and making some other things clear and unambiguous, possibly unintentionally or possibly perversely. no matter. same view. at least to me.
beyond that, it ain't worth commenting on further.

Jim Rooney - 2008/11/24 05:18:15 UTC

Well, I'm assuming there was some guff about the tug pilot's right of refusal?
Gee, didn't think we'd have to delve into "pilot in command"... I figured that one's pretty well understood in a flying community.

It's quite simple.
The tug is a certified aircraft... the glider is an unpowered ultralight vehicle. The tug pilot is the pilot in command. You are a passenger. You have the same rights and responsibilities as a skydiver.
It's a bitter pill I'm sure, but there you have it.

BTW, if you think I'm just spouting theory here, I've personally refused to tow a flight park owner over this very issue. I didn't want to clash, but I wasn't towing him. Yup, he wanted to tow with a doubled up weaklink. He eventually towed (behind me) with a single and sorry to disappoint any drama mongers, we're still friends. And lone gun crazy Rooney? Ten other tow pilots turned him down that day for the same reason.

Tad Eareckson - 2008/11/24 06:16:08 UTC

Brian Vant-Hull - 2008/11/24 03:35:02 UTC

Tad - please stop acting like everyone has to conform to your version of absolute truth.

The United States Hang Gliding and Paragliding Association, Inc.
SOP 12-02
Pilot Proficiency Program
2.10 USHPA Hang Gliding Aerotow Ratings
B. USHPA Aero Vehicle Requirements

5. A weak link must be placed at both ends of the tow line. The weak link at the glider end must have a breaking strength that will break before the towline tension exceeds twice the weight of the hang glider pilot and glider combination. The weak link at the tow plane end of the towline should break with a towline tension approximately 100lbs. greater than the glider end.

1. Can we PLEASE PLEASE PLEASE once and for all drop this crap about this being -MY- version of absolute truth?

2. Would someone - Brian, Janni, Lauren, ANYONE - PLEASE PLEASE PLEASE explain to me how the tug's ass is endangered by a double loop ONLY when it's on a SOLO glider - but not at all when it's on a TANDEM?

Brian Vant-Hull - 2008/11/24 12:46:17 UTC

Ooh, a demonstration of how shorter really is much better. I have to back to the sidelines on this, but must say it's a damn good comeback. Jim?

Janni Papakrivos - 2008/11/24 15:30:25 UTC

Using weak links that are able to hold the tug's entire permitted take-off weight is madness for one. You can take those regulations, light and smoke them Tad. It may not be your truth, but not seeing through the bull is clearly your failure.
I'll give the tandems a pass, highly trained and competent instructors on single surface gliders and an equally competent tug pilot. Got nothing to do with, for example, me showing up with my Litespeed asking to be towed. Those two things are not on the same page, they are not even in the same book.

Brian Vant-Hull - 2008/11/24 17:19:34 UTC

1. "Using weak links that are able to hold the tug's entire permitted take-off weight is madness"

Unsupported statement. Please state references or easily verifiable personal experience.

2. "You can take those regulations, light and smoke them Tad. It may not be your truth, but not seeing through the bull is clearly your failure. "

Ambiguous pronoun. What does 'it' reference?

3. "I'll give the tandems a pass, highly trained and competent instructors on single surface gliders and an equally competent tug pilot. Got nothing to do with, for example, me showing up with my Litespeed asking to be towed. Those two things are not on the same page, they are not even in the same book."

This argument has merit, but the author is urged to refrain from the use of linked metaphors.

Summary: to this reviewer half the submission is worthy of inclusion in the present collection, but the introduction should be rewritten in a less subjective framework. The author is urged to make major revisions as indicated above.

Jim Rooney - 2008/11/24 18:12:06 UTC

Sorry Brian, I don't read Tad's posts.
If you want my opinion on something, you'll have to post the question.

Brian Vant-Hull - 2008/11/24 18:23:07 UTC

Jim - I quoted the whole thing. (yes that was the whole thing, short for Tad, which is what makes it worth looking at).

Janni Papakrivos - 2008/11/24 18:23:52 UTC

Glen + gear = 350 lb.
2G upper limit weak link = 700 lb.
Maximum take-off weight Dragonfly = 661.5 lb.

Brian Vant-Hull - 2008/11/24 18:27:54 UTC

Janni - why is that madness? Most of the max tow forces are caused by acceleration, not weight. you probably incur greater than 1 g acceleration walking into a door.

Jim - look below the dashed line in that post above. That's quoting Tad.

Jim Rooney - 2008/11/24 18:54:27 UTC

I'm confused. I never said the tug's ass was endangered. That's why we use 3strand at the tug's end. Using 4 strand can rip things off (it's happened). When forces are achieved that do break a 3 strand, your tail gets yanked around very hard, which does have implications as to the flight characteristics and flightpath. AKA, I have no desire to allow you to have the ability to have that effect on me when I tow you... esp near the ground.

What I said was that by using a weaklink that's stronger than the tug's, you're effectively removing your weaklink. Big difference.

Yes, this is what tandems do... because they must. A tandem with a single weaklink doesn't even leave the ground (it's been tested). You on the other hand have a choice.

By using a 4 strand weaklink, the tandem flies with the tug's weaklink as "the weaklink". Both the tug pilot and tandem pilot understand this and agree to it. I personally tow behind Zach more in a weekend than most (any?) of you tow in a year. We both have a clear understanding of the added risk we incur.

A tandem with a four strand weaklink is not equivalent to a solo with a 4 strand btw. Tandems are way heavier than even the fattest of the fatboys out there. The principle of removing the glider weaklink is the same, but the tug's weaklink is effectively stronger with a solo. Weren't you the one advocating "scaling" weaklinks?... this concept should make perfect sense to you then.

That cover it?

Brian Vant-Hull - 2008/11/24 19:13:53 UTC

Very good. Somewhere around 3 strands of greenspot is the upper limit set by equipment tolerances.

then the question becomes, does going significantly weaker help or hurt you? Apparently highly skilled pilots think so highly of their ability to prevent bad situations by either flying out of it or releasing that they are willing to risk not only themselves but a passenger. Would these same skilled pilots prefer a stronger or weaker link in gnarly conditions?

Janni - I was trying to be funny. But maximum g force can only be set by testing, not saying ad hoc that a certain value is insane. Jim's ripping apart equipment sounds like a test.

Brian Vant-Hull - 2008/11/24 19:18:16 UTC

BTW, my one strand weak link puts my glider above 1 g. Madness?

Janni Papakrivos - 2008/11/24 19:26:42 UTC

I still love you Brian. Jim, is a 700 lb. weak link for a guy like me madness or not, seriously?

Jim Rooney - 2008/11/24 19:38:03 UTC

Brian Vant-Hull - 2008/11/24 19:13:53 UTC

Would these same skilled pilots prefer a stronger or weaker link in gnarly conditions?

Weaker.

I think you missed something very important... you seem to be under the impression that we choose to fly with 4strand. That somehow we have an inflated sense of our skills that "it's ok" so screw it, we'll use a strong link. This is not the case. We do it because we have to.

Is a 700lb weaklink madness?
Yes

Jim Rooney - 2008/11/24 20:34:53 UTC

Something else occurred to me...
There seems to be the impression that I think that because I fly so much, that I "can handle more". In fact, you have the impression that I'm so comfortable with this notion, that hell, I'll take someone else along.

Not at all.
I can handle less tandem. I have less safety devices tandem... in addition to a lesser weaklink setup (read stronger glider link) the tandem parachute is slower to deploy (must be used higher) and I have more weight to throw around (solo gliders are more easily maneuvered). I also have a passenger, and who knows if they're going to start grabbing sh*t? The deck is stacked higher against me tandem.

What I have is the understanding that I can't fly in the same crap that I could solo.... because my margins are lower. I have a familiarity that allows me to know when to STOP FLYING... which is always WAY sooner than I would solo. That's what flying every day with the same people and equipment does for me.

Brian Vant-Hull - 2008/11/24 21:25:19 UTC

If a light and a heavy pilot pull the same manuever, they will pull the same number of g's. So a pilot that's twice as heavy will exert twice as much force doing the same thing. So the same link will mean the heavier pilot can't fly the same way as the lighter pilot. Either the lighter pilot is less well 'protected' by the weak link, or the heavier pilot is being shafted by having more weak link breaks while doing the same thing.

Yes, can't go too close to the tug's weak link strength. But staying below that, why should the pilots be treated differently?

Jim Rooney - 2008/11/24 21:46:28 UTC

Didn't we already cover this?
So long as you're under the tug's link strength, it's not about weight. (Note, under... not equal)

Find a material that meets/exceeds greenspot in all aspects and you've got something.
Hand made stuff doesn't cut it. Handmade has no quality control and no standards. It is not identifiable.

I've yet to hear anything from anyone that even comes close. If it's out there, bring it on.
Till then, you're stuck with greenspot.

Brian Vant-Hull - 2008/11/24 22:40:43 UTC

Okay, just wanted to make sure it was clear.

So Janni, either you think my link is dangerously strong, or yours is inconveniently weak. Until some very experienced AT jock pulls me aside and tells me I should be worried about my safety, I'll say your link is inconveniently weak.

Unfortunately, we don't have a material with which to adjust it that every tow pilot will recognize and be comfortable with. The next step up is 3 strands, and that's not 100 lbs below the tug.

Tad is making adjustable links, but the next step would be convincing everyone that they are as reliable as he says (and greenspot wears out, remember), and more importantly, that he's not making any that are stronger than 100 lbs below the tug. I guess that doesn't leave much room to maneuver anyway, does it?

Beef up the tug so it can take a stronger link? Moving into uncharted territory.

No more little debbie cakes for me, gotta keep my g loading down.

Jim Rooney - 2008/11/24 23:38:01 UTC

It's not "uncharted territory"... you're just not aware of what's been done. Just as you weren't aware of the reason for 3 strand links on the tug.

The trouble with Tad's links is not convincing people. It's not an opinion problem. It's a testing problem. Just as a hand made glider would be a problem.

You're probably also not aware that me and Paul had a pretty big argument over his Tad-o-link before he locked out in Texas. All these same arguments. Over and over. No one listens till they scare themselves...
Until some very experienced AT jock

-slaps forehead-

Brian Vant-Hull - 2008/11/25 00:01:15 UTC

Janni and I fly with the same standard weak link. I was just trying to make Janni's life as easy as mine, but it's harder than I thought it would be.

Janni Papakrivos - 2008/11/25 02:42:35 UTC

Brian, I never said you were flying with a dangerously strong weak link. I never said I was inconvenienced by mine.
I may break a few more than you do in a season's time, but they may also break sooner than yours when shit hits the fan. I believe that both you and Jim agree with me on that. If not, where am I mistaken?

Brian Vant-Hull - 2008/11/25 03:24:25 UTC

Just think of yourself as the Joe the Plumber of towing.

Janni Papakrivos - 2008/11/25 03:32:37 UTC

LOL

Tad Eareckson - 2008/11/25 12:28:55 UTC

http://www.chgpa.org/forums/viewtopic.php?f=2&t=2871
speed link

Jim Rooney - 2008/02/06 23:14:48 UTC

Eat something else... he copied that design.
A properly constructed Bailey has a stop (a rivet) that prevents this from happening.
How do I know this?... I was one of the guys that pointed out the problem to him (and how a Bailey doesn't have this problem).

So credit where credit is due... the "brilliance" here belongs to Bobby.

http://www.liteflite.com.au/ProductsChestTowRelease.aspx
LiteFlite - Home of the Dragonfly

On the remaining issue which had not been previously discredited... Apparently not.

NEVER TRUST A WEAK LINK!
Expect two things from your weak link:
(1) It will break unexpectedly at the most inopportune time, with no warning adn no indicaiton of a flight problem.
(2) It will hold strong and fast whenever you move into a lockout.

Then I switched to the falcon and the birds were singing in tune again. Until the brand new weak link vaporized at about 1000 feet for no apparent reason.

At 840 feet I noticed the tug was high and rising so I pushed out a bit to catch up. Broke the weaklink and stalled since I was so nose-high.

First try was a notably short flight, with a weak link break moments after lifting from the launch cart. The wind had shifted, so I had a down-wind landing, rolling in. I succeeded in dragging a knee instead of a toe on one side, so I earned a nice strawberry scrape.

I got five launches with three full flights on the US. Two weak link breaks. Both were non-issues.

Got to Ridgley after 12, late as usual and was one of the last to launch. Broke a weak link. From now on I use a new weak link every time since they're giving us dental floss now.

Kristen attached me to the plane and I rose briefly in the air. Pop! My weak link broke. (...The bad part is that sometimes the links just break, for no particular reason.)

Just a quick story with good educational value for other tow pilots. Yesterday I was the second of 3 off cart weak link breaks behind a 914 tug. Turbo was kicking in too quick says Bo.

I bent one this year when I had a weak link break right off the cart...

I had a weak link break at maybe 50 feet. I thought I was going to have to land in the soybeans -- the very tall soybeans -- when I looked at my angle. But, my glider stalled quite dramatically almost instantly (hard not to stall when you have a break), and dove towards the ground (a bit disconcerting from so low).

...I hit enough turbulence to break my weak link. #%*&!

Steve had a weak link break on his first launch just after leaving the cart and rode it in on the asphault.

A second later, we are horrified to see her weak link has broken. We know she has been well prepared, but we want her first flight to be perfect.

...but at 400 feet my pussy-##s weak link broke.

I had a late start due to a weak link break.

Being a "large and tall" pilot (6' and 225lbs) on a big glider, I don't get pushed around as much by thermals...but then again, I'm pushing the weak link that much closer to its breaking point (since everyone tends to use the same test-strength line for the link).

I've only had one weak link break while aerotowing and it happened while I was still very low and over the runway. I was happy that I automatically pulled in as soon as I heard the snap and got slow.

One of the more interesting and poinient ones is the smooth air break. Towing up in smooth air, in position and you have a good weaklink... just towing along straight and level, nice and smooth... when the weaklink breaks. There's no appearent reason. No rough air, no rough glider inputs... it just breaks.

Broke the weak link at 100' this time. The tow was a little rowdy, but not that bad. Don't know what caused the break.

This time the link broke at 900'. Damn.

Broke the weak link at 1000'. And it was a fairly mellow tow.

I was in line early but had a green tow pilot. My weak link broke after an extremely fast 350 feet.

Anyway, on my first tow, Tex entered a thermal at just over 1100 AGL, and I failed to track properly behind him. I got turned away from him (not badly) and as I was about to get back into position the weak link broke at 1200 AGL.

I could feel a huge gust hit right as I came off the cart. Uh oh. I was right behind the tug at maybe 100 feet when my link broke. (Kev said yesterday the weak link might have also broken because of the very powerful tug, which throttled back yesterday.)

My weak link broke for no obvious reason at ~2,000' as Zack was pulling me in a wide turn to get back into a thermal he had found earlier.

Jim Rooney - 2008/11/23 19:42:44 UTC

Greenspun get's used because it's manufactured. It's a common and standard material. You can get it at a fishing store and everyone knows what it is. This seems trivial, but it's again one of those things that looks small, but isn't.

Argue all you like about the validity of it's consistency in manufacturing (I know Tad will), but here's the rub... it has a testing system in place. And it far exceeds anything any non manufactured article could hope to achieve.

Yup, the tolerances of the "standard" 130 pound Greenspot loop are truly incredible. How could one possibly improve on a record like that?

Just two things are important here. "Greenspun" is "manufactured" and "it has a testing system in place".

The testing system in place is, of course, "assume that a link blows at 260 pounds of direct tension, skip the bench testing, slap it on every glider that shows up, ignore the fact that it routinely fails under a direct load of anywhere between 63 and 140 pounds, and assume that - if nobody gets killed - it's record can't be improved upon."

And it far exceeds anything any non manufactured article could hope to achieve.

And if Sunny is using something else with tolerances of around plus or minus five percent - hell, just ignore the extensive data which undermines your position.

Jim Rooney - 2008/11/24 21:46:28 UTC

Find a material that meets/exceeds greenspot in all aspects and you've got something.
Hand made stuff doesn't cut it. Handmade has no quality control and no standards. It is not identifiable.

I've yet to hear anything from anyone that even comes close. If it's out there, bring it on.
Till then, you're stuck with greenspot.

Jim Rooney - 2008/11/24 18:12:06 UTC

Sorry Brian, I don't read Tad's posts.

Yup, why bother listening to ANYONE when you've known everything worth knowing since age five?

Jim Rowan - 2008/11/25 13:57:52 UTC

Now if that's not the pot calling the kettle black, I don't know what is.

Tad Eareckson - 2008/11/25 16:02:40 UTC

Would someone - Brian, Janni, Lauren, ANYONE - PLEASE PLEASE PLEASE explain to me how the tug's ass is endangered by a double loop ONLY when it's on a SOLO glider but not at all when it's on a TANDEM?

Brian Vant-Hull - 2008/11/25 16:49:09 UTC

Okay, a lot of people are throwing around how much knowledge they have related to towing. Let's test it.

You are a pilot with hook-in weight of 190 lbs, flying a 70 lb glider. You are handed a loop of commercially tested greenspot by the flight crew. You are flying standard configuration: bridle to each shoulder, release suspended from the keel.

1. based on the rating of the greenspot, what number of G's will the flight crew tell you the loop is good for?
2. based on Tad's tests, what number of G's is the loop good for?

How many of you can pass this test?

Janni Papakrivos - 2008/11/25 18:45:19 UTC

Brian, this discussion to me is only relevant for one scenario. Big guys, the major target group of Tad's futile efforts, with greenspot weak links entering a high line tension lockout and not releasing. I don't give a rat's ass about anything else that could and might and will likely never. So, in that particular scenario, Brian or Jim, if you were in my shoes, would you want something that breaks at 0.8 G, 1+ G or 1.4+ G? If I get an answer to that question from either one of you I will gladly leave this discussion and wait for something new to debate you guys on

Jim Rooney - 2008/11/25 19:21:57 UTC

Brian,
While I appreciate your quest for the perfect weaklink, didn't we cover this already? (Again?)
Are we to go down the road of debating the quality standards of greenspot again?
Ok, for review, it doesn't matter.
Why?
Because you have nothing else.
Do I have to review why we don't tow handmade gliders?

Listen we're all perfectly aware that greenspot is not laser calibrated to 130lbs. It's bloody fishing line. Get over it. Are you flying below your perfect numbers as a heavy guy. Yes. Yes you are. Get over it.
Why?
Because it's all you've got.

Why lower numbers? Because your choice is lower or higher... and higher is more dangerous than lower.
Plain and simple. Janni, 1G, but please stay.

Now, my turn.
Name one commercially available strength rated material that can be used as a weaklink OTHER than greenspot.

Tad Eareckson - 2008/11/25 19:38:35 UTC

http://www.tost.de/evers/edefault.htm
http://www.wingsandwheels.com/page30.htm

http://www.flickr.com/photos/aerotowrelease/

Brian Vant-Hull - 2008/11/25 20:16:56 UTC

I posted the quiz to point out that most people don't feel comfortable analyzing the situation in the first place. Plus one would think when you loop 130 lb test greenspot you get 260 lbs minus some small amount for wrapping it around a bridle (hiding the knot from direct tension), but most people would be surprised to find that Tad tested the loops to be around 140 lbs. Most professionals don't even know that. And it abrades with time.

It's not kept because it's reliable or even well understood, it's kept because folks recognize it so they feel comfortable.

Tad has posted a site that has plastic strips for weak links, with holes cut in them to decrease the strength as needed. Seems better than the stuff we use now, with more room for adjustment. Made by a company focussed on towing.

I think heavier pilots should have a choice to increase the weak link strength to within the specified 100 lbs below the tug weak link. The links will be more expensive, but also replaced less often.

Jim Rooney - 2008/11/25 20:49:28 UTC

It's not kept because it's reliable

There are a couple thousand successful tows that tend to contradict that statement.

or even well understood

I work with a lot of people that would tend to disagree with that.
Just because the solo pilot crowd isn't aware, please do not assume this.

One criteria is of course that they are recognizable... to me... not you.
But that's not it. They are kept because they have a huge track record. That's really hard to argue with.
I've yet to hear anyone successfully do so.

Plastic links...
"Manufactured by Bob" doesn't meet my criteria.
They are not manufactured to tolerances. They're not "manufactured" at all... They are a material that some guy found consistent enough to feel comfortable about. He cuts holes and tests, but it's still Bob in his backyard. He doesn't make the plastic, so he has no control over the quality of it.
That said, I'd feel a whole lot better about these than Tad's stuff.

Brian Vant-Hull - 2008/11/25 21:04:53 UTC

Oh come on, you think the makers of greenspot start with the raw materials? they get stuff from other folks they don't control.

Of course the community has to use something they feel comfortable with, and can't go switching willy nilly. But if something is out there that everyone has access to and it would allow some more control, isn't it worth looking at?

Granted, it's a small company in a niche market that could go belly up any time. I'd prefer something like greenspot that is weaker so a multiple loop method could be used with more room for adjustment. No doubt the towing community has already been through this and settled on the best they could do. But it's worth looking every few years, isn't it?

Anyway, I don't see much more to say unless the tug link can be made stronger.

Jim Rooney - 2008/11/25 21:39:06 UTC

Agreed, it seems trivial, but it's actually a large difference.
(Notice a trend?)

The difference is when the quality control happens, and to what extent. Commercially available material that's sold as load tested is held to standards. There is a huge difference between a backyard production run and something that's available quite literally around the world. The volume difference is absolutely massive. The quality control sampling is far far greater than whatever a single person, or even a single outfit can muster. It's simply night and day.

See the fishing line isn't being made from raw materials with an assumption of quality. The testing happens after it's produced. And happens on an absolutely massive scale. There is no assumption of quality of the raw materials.

The plastic links are assumed to be made to a certain tolerance and then tested by Bob in very limited quantities. The quality of the raw materials is assumed. Big big difference.

And yep... thanks for pointing out the futility of all this... You're confined to certain parameters (tug's link), so discussing things outside those parameters is pretty darn pointless.

Janni Papakrivos - 2008/11/25 22:40:36 UTC

Why lower numbers? Because your choice is lower or higher... and higher is more dangerous than lower.
Plain and simple. Janni, 1G

I won, I won!!!
What was your point about nylon vs. dacron in harness suspensions again, Tad?

Brian Vant-Hull - 2008/11/26 00:38:17 UTC

Jim;
From the website Tad found:

In 2005, we celebrated the company's 60th anniversary. All these years, our business has been located on the same site in the heart of Munich...

This company has been manufacturing towing products longer than hang gliding has been in existence. Gee, somebody trusts their products, and its a larger community than hang gliding. Maybe it's time to get less provincial?

Janni - I wouldn't say it's settled that weaker is safer. Try a link that's just enough to lift you partway off the cart then dump you. And do it without wheels. Two opposing safety standards, there's got to be a sweet spot, even if we haven't found a way to know for sure where it is.

Gene Towns - 2008/11/26 01:33:33 UTC

Otto Lilienthal, wasn't he out there back in the day running the hills? I can't recall what airport I was in, there was a replica glider hanging from the ceiling. I wonder if they utilized weak links back then.

Jim Rooney - 2008/11/26 08:14:54 UTC

Fair enough... there you have it then.... grab one of their weaklinks at your appropriate size and dispense with all this drama an all these silly hand made weaklinks.

Those "toast" weaklinks fit all the criteria then?... Tad's still do not, btw... nothing's changed there. So... if Tad really is seeking to improve safety... will he now give up making weaklinks and instead start pushing these?

Brian Vant-Hull - 2008/11/26 12:47:25 UTC

Good enough. I'm done. Sorry for hanging in here for so long, I just wanted to show Tad that if you didn't treat a discussion like a street brawl you could actually make progress. He may actually have more up his sleeve, but now it's his turn.

Janni Papakrivos - 2008/11/26 16:34:51 UTC

I checked the site out, those are indeed neat. Thanks for finding that, Tad.
I'll be in Germany over Christmas and think I could buy a few of those if there is interest. Let me know.

Tad Eareckson - 2008/11/26 23:36:17 UTC

Brian,

Thanks much for taking the heat off me for a while and greatly amending the rational component of this discussion. Above and beyond the call of duty.

But - as to making PROGRESS?

Did you catch this...

Janni Papakrivos - 2008/11/25 18:45:19 UTC

So, in that particular (lockout) scenario, Brian or Jim, if you were in my shoes, would you want something that breaks at 0.8 G, 1+ G or 1.4+ G?

Jim Rooney - 2008/11/25 19:21:57 UTC

Plain and simple. Janni, 1G

Janni Papakrivos - 2008/11/25 22:40:36 UTC

I won, I won!!!

Did you catch that? Want me to play it again? Nah, waste of bandwidth, just go back and reread it a couple of times.

(Let's first remember that that dialog occurred in an exchange that was meant to conceal the fact that neither correspondent had any idea how to calculate the solution to the quiz question you posed and that the one who isn't Janni has no concept of what G loading is to begin with anyway.)

If Janni goes up to the flight line and asks for a weak link to put on the end of his two point bridle, Jim hands him a single loop of Greenspot and says, "Here ya go - One G."

If Karen goes up to the flight line and asks for a weak link to put on the end of her one point bridle, Jim hands her a single loop of Greenspot and says, "Here ya go - One G."

Of course Janni's translates to 0.76 Gs - but that figure is only good before the cart starts rolling. By the time he releases the hold-downs the weak link has degraded and he's down to point five or six.

Karen's loop is 1.4 Gs and tends to stay that 'cause she has a lot of margin before she's stressing and degrading it.

What I'm trying to do is get a floor defined. I can live with 0.8 (FAA and everybody else) IF, in fact, the 0.8 STAYS 0.8 for the duration of the tow. But I'd like to see 1.0 (just like Jim).

Again - that's the MINIMUM I'm talking about.

But I'm RECOMMENDING folk fly 1.4 - Karen with the magic "1.0" weak link towing off her shoulders.

So - recap - Janni asks Jim if it's safe to go below 1.0. Jim says "NO WAY!" but nevertheless WILL NOT ALLOW him to tow anywhere above half to three quarters of that.

(Bear in mind that a double loop puts him at 1.09.)

So you'd think it was more like - I won, I won!!! - but that would only apply in a strange parallel universe in which two plus two equals four.

Don't worry. This thread won't go on much longer. As soon as this cold spell is over they're not gonna have much trouble finding the storm drain into which I stuffed the body of my court appointed anger management therapist. After they run the DNA analysis on the tissue they'll find underneath her fingernails my story about being attacked by the Black Bear that was raiding my garbage can is going to unravel even faster than that fishing line I used to fly.

Janni,

Enjoy Christmas if you're going back to Germany anyway but don't make a special trip for the weak links - you can order them from Tim of Wings and Wheels in Lakewood, New York. That's how I got a couple of assemblies and the first six of the low end of the insert series a couple of years ago.

However, given the constraints outlined earlier in this discussion, they won't really do anyone much good.

Right now it's a pretty good bet that I'm the only one who understands WHY 'cause it's a pretty good bet I'm the only one who's actually done the testing.

You can probably rely on Jim's clairvoyance to come through once again however. Run it by him and we'll compare/contrast.

Danny Brotto - 2008/11/26 23:40:39 UTC

My glider port uses Tost weak link rig. I tow with one just about every weekend so I'm familiar with it. They are really not for "individual" use. The entire rig is metal and weighs a good bit. It's ment to go inline between the tug and the glider not within the bridle. I would want it to be well in font of me too so as to not get whacked with all that metal flinging around. The weak-link itself is encased between two slabs of metal.

We used to use a length of polypro line; essentially the entire line was the weak link. We found that after a weekend's of use the strength was severely degraded by abrasion. We moved over the Tost system that uses a strong line that's resistant to abrasion coupled with the Tost weak link assembly. Our weak link sports a one-size-fits-all break strength within the specifications of the FARs.

We do have a Sparrowhawk ultralight glider and we uses his own lighter-weight weak link.

Brian Vant-Hull - 2008/11/27 02:58:34 UTC

The entire rig is metal and weighs a good bit. It's ment to go inline between the tug and the glider not within the bridle. I would want it to be well in font of me too so as to not get whacked with all that metal flinging around. The weak-link itself is encased between two slabs of metal.

Wasn't I clever to bow out of the discussion when I did?

Lauren Tjaden - 2008/11/29 14:46:02 UTC

From the Oz Report, about a fatal hang gliding towing accident in Hay (05):

http://ozreport.com/9.127
Robin's accident

Davis Straub - 2005/06/14

Once the glider bounces off the ground, Robin is never able to get the glider lined up correctly behind Bobby Bailey and drifted continually to the left, locking out and crashing from a low altitude. If Bobby had released Robin at any time before the last two or three seconds he would likely not have crashed, at least not from a lockout.

Remember that Robin's bridle and weaklink failed. He attempted to release and was unable to do so.

Being stuck to the plane is not always good.

I know personally of another incident that occurred this year in a tandem (not at Quest, not with me). A pilot with limited tandem experience took up a tandem passenger behind a tug pilot with limited midday experience. The hang gliding pilot had difficulty controlling the glider's pitch due to bad flying on the tug pilot's part. He should have released earlier, but didn't. By the time the glider released the tandem had been stressed pretty hard. The tandem pilot safely landed the tandem. Afterwards, while examining the glider to ensure that it had not been overstressed, it fell apart on the ground. Very lucky it was not a double fatality.
The pilot will report this in a timely fashion but it is not my place to reveal details. The weak link did not break.
Being stuck to the plane is not always good.

Tad Eareckson - 2008/11/29 20:49:16 UTC

http://ozreport.com/9.032
The Worlds - weaklinks

Davis Straub - 2005/02/07

Weaklinks? We don't need no stinking weaklinks.

Rohan Holtkamp (in blue text below) at Dynamic Flight <dynamic> responds to my response (in black) to Angelo re Robin's death (http://ozreport.com/9.026#2):

The supplied weaklinks and each roll of material was selected (one week before the comp) after testing proved that the breaking strain to be plus or minus 5% from 118kg, as promised in the local rules.

Robin's own release failed to release, plus he refused our weaklink, even to the point of yelling and physical threat. After viewing video evidence of the entire flight, even a 80kg weaklink would have made little difference. His actual weaklink did test to be stronger than 180kg, but that was not the primary cause of his accident. Release failure was, same as Mike Nooy's accident. A full lockout can be propagated with less than forty kg of tension. Read "Taming the beast" on our website and/or come have a look at the video if you doubt this in any way.
...
(editor's note: So if weaklinks don't do much to save us from lockouts, an argument heard repeatedly at the Worlds, then why are we using them after Robin's lockout (and not before)? Shouldn't we have all gone to the Pro-tow or other type of bridle instead, as it was not the weaklink that was at fault in Robin's accident, but the bridle (as your investigation discovered)?

What exactly is the point of weaklinks? Why should we be using them? What is the tradeoff in safety between breaking a weaklink and thereby having a problem, and not breaking a weaklink and thereby having a problem?
...
Of course, I realize that there are some circumstances where weaklinks are useful. It is just that weaklinks suddenly became THE issue after Robin's death, when in fact, as you argue here, and as you laid out then, it was not the lack of a reasonable weaklink that killed Robin, but the failure of the release mechanism, the bridle.

Perhaps if you laid out the case re the tradeoffs involving weaklinks, we could make a better decision about them. For a couple of years I have flown with a doubled weaklink because, flying with a rigid wing glider, I have found that there is little reason to expect trouble on tow, except from a weaklink break. Am I wrong in this?

The supplied weaklinks and each roll of material was selected (one week before the comp) after testing proved that the breaking strain to be plus or minus 5% from 118kg, as promised in the local rules.

...as usual, with ABSOLUTELY NO CONSIDERATION of the weight of the glider. Karen and Glen get the same idiot piece of string. Thus, she is deemed to be safe ONLY at 1.30 Gs and he ONLY at 0.74. Ya gotta wonder how this depth of stupidity can be this widespread and this ingrained for this long.

His actual weaklink did test to be stronger than 180kg...

USHPA SOP 12-02:2.10:B:5

...The weak link at the glider end must have a breaking strength that will break before the towline tension exceeds twice the weight of the hang glider pilot and glider combination...

If Robin was Karen's weight or more he was flying in compliance with globally established and recognized aerotowing standards.

...it was not the lack of a reasonable weaklink that killed Robin, but the failure of the release mechanism...

No fucking "IF" about it - I've seen the film.

For a couple of years I have flown with a doubled weaklink because, flying with a rigid wing glider, I have found that there is little reason to expect trouble on tow, except from a weaklink break.

For a couple of years I have flown with a doubled weaklink because, flying with a rigid wing glider, I have found that there is little reason to expect trouble on tow, -except from a weaklink break.

What exactly is the point of weaklinks? Why should we be using them?

http://www.dynamicflight.com.au/WeakLinks.html
Weak Links - Dynamic Flight Hang Gliding School

The purpose of a weak link is solely to prevent the tow force from increasing to a point that the glider can be stressed close to or beyond its structural limits.

Afterwards, while examining the glider to ensure that it had not been overstressed, it fell apart on the ground. Very lucky it was not a double fatality.

Two assumptions:

Dragonfly.

Max weak links installed on bridles at both ends of the tow line - double loops of 130 pound Greenspot.

No mention of a lockout so it's a pretty good bet it didn't happen.

So let's see... What can we learn, what can we learn...

The glider was MAYBE loaded up a bit while still very much controllable and WITHOUT locking out, which - as only the more clueless amongst us have yet to understand - does not generally translate to significant stress. (See:

http://www.youtube.com/watch?v=F_n5B3-MIC4


IF this glider was damaged in the course of that tow it was a fucking DEATHTRAP well before it was hooked up behind the tug. One solid thermal surge during free flight would have been all that would have been needed to fold it up and spit it out of the sky. It was no fucking way adequately preflighted.

The pilot will report this in a timely fashion...

Nah - Not possible. For this disaster to be reported in a timely fashion the two pilots involved would have needed to have clicked "Submit" to USHPA and the Oz Report within an hour and a half of the glider's collapse.

Being stuck to the plane is not always good.

How is that statement REMOTELY relevant to this situation?

No tug/glider combo operating within the terms of USHPA SOP 12-02:2.10:B has EVER been stuck together for more than a second or two. As far as I can tell from this scant information... aside from some sloppy technique, between launch and landing neither pilot did ANYTHING wrong.

Tad Eareckson - 2008/11/30 07:44:47 UTC

Bacil,

If you're still lurking...

At the beginning of August of last year I said:

http://www.chgpa.org/forums/viewtopic.php?f=2&t=2467
weak links

Tad Eareckson - 2007/08/01 11:56:37 UTC

If you crater in it won't be 'cause the tug fell apart, the driver decided to kick in the turbocharger, dump power, and/or fly under the power lines, the engine ran out of gas or seized, the tow line or weak link broke or didn't, the tug's release was or wasn't actuated or jammed, or the tow line wrapped or carabiner hooked on to your wires.

It'll be 'cause you screwed the pooch.

Gotta backpedal a bit on that blanket statement.

As per some of the recent discussion, it is possible to be in the extremely rare situation resulting from no pooch screwing whatsoever by anyone in which one's continued good health does indeed depend on gasoline, oil, a substantial weak link, and a tug pilot not overly trigger happy - Bob Koshmaryk being the best example.

http://groups.yahoo.com/group/skysailingtowing/message/6744
Weaklinks

Donnell Hewett - 2008/11/05 21:22:29 UTC

...I am sure you can imagine more than one situation where getting off line is the worst possible alternative you can take. In such cases, the towline becomes a "lifeline" rather than a "death-line". It pulls you out of danger rather than plunging you deeper into danger.

Danny Brotto - 2008/11/04 12:49:44 UTC

An instance where the weak link could have broken and I'm glad it didn't...

I had the Axis on the cart with the AOA a bit high, launching to the west, with a moderate 90 degree cross from the left. I came out of the cart rolled and yawed to the right with the upwind wing flying and the downwind wing stalled. It was rather dramatic. If I had released or if the weak link had broken, the downwind wing would have further stalled and I would have cartwheeled into terra firma in an unpleasant fashion. I held on tight gaining airspeed until the downwind wing began flying, got in behind the tug, and continued the flight.

Sunny later told be he was about to give me the rope and I thanked him to no end that he didn't...

That's why the following scares the crap out of me.

http://www.chgpa.org/forums/viewtopic.php?f=2&t=2467
weak links

Jim Rooney - 2007/07/22 16:59:30 UTC

...Just don't tell me that weaklinks need to be stronger! That's just flat out ignorant.

Jim Rooney - 2007/08/01 13:47:23 UTC

Here we go again with more of the "you're better on tow in a bad situation" BS.
The #1 thing I can do for you just off the ground is GIVE YOU THE ROPE.
Whatever's going on back there, I can fix it by giving you the rope...

Jim Rooney - 2007/08/01 19:49:30 UTC

Tad's saying that I can fix things without giving you the rope.
...
It's more of this crappy argument that being on tow is somehow safer than being off tow.

Brian,

If one were to take at face value the tandem incident Lauren related...

A Dragonfly was able to totally destroy a tandem glider with no more than 348 pounds of tow line tension while itself suffering no damage whatsoever.

Wouldn't that tend to make total hash out of Deepfloat's concern for the delicate structure of a solo dragging tug?

(Rhetorical question - no response expected or needed.)

Bacil Dickert - 2008/11/30 14:12:15 UTC

Tad,
I know I'm playing Mr. Obvious here, but remember there are two people's butts on the line during a tow. It ain't just all about the caboose, it's also about the locomotive. I would trust Jim's statements about his "safety" moves if he determines that the situation behind him is endangering his well being.

Marc Fink - 2008/11/30 18:03:24 UTC

Lauren Tjaden - 2008/11/29 14:46:02 UTC

I know personally of another incident that occurred this year in a tandem (not at Quest, not with me). A pilot with limited tandem experience took up a tandem passenger behind a tug pilot with limited midday experience.

Tug and tandem pilots with limited experience at the same time? Holy crap!

Janni Papakrivos - 2008/11/30 19:07:30 UTC

I went truck-towing yesterday. I noticed that line tension wasn't changing much no matter what I did with that Falcon. I realized I could totally kite my glider into the ground without the weak link ever yielding.
Could it be that Tad got those two mixed up?

Carlos Weill - 2008/11/30 19:24:09 UTC

Incident 1
On June of 2008 during a fast tow, I noticed I was getting out of alignment, but I was able to come back to it. The second time it happen I saw the tug line 45 deg off to the left and was not able to align the glider again I tried to release but my body was off centered and could not reach the release. I kept trying and was close to 90 deg. All these happen very quickly, as anyone that has experienced a lock out would tell you. I heard a snap, and then just like the sound of a WWII plane just shut down hurdling to the ground, only the ball of fire was missing. The tug weak link broke off at 1000ft, in less than a second the glider was at 500ft. At that point I realized I had the rope, so I drop it in the parking lot.

Mistake #1 Did not stay behind the tug
Mistake #2 Did not release earlier
Mistake #3 Did not use the secondary

Incident 2
As a background, after release I wrap the bridle on my hand to stow it away. The bridle is the 3-point brake release in the hangloop carabiner. More than 18months ago 2007, under during a turn when tow forces were too strong, my weak link broke. But bridle was still attached to the tug because the bridle was coiled and had wrapped itself around the carabiner. However I had left the weak link intended for pro-tow on the harness and it broke. This happened in no more than 2 seconds.
Since then I when I set-up I make sure the bridle has no twists and still keep the pro-tow weak link.
I welcome any face-to-face questions or comments on these incidents. Anyone who wants recommendations for their towing or training, you have a great pool of knowledge in the tow parks especially from the ones that do it regularly and have the experience in the tug and behind the tug.

Dan Tomlinson - 2008/11/30 19:40:16 UTC

Carlos if you have a vario that can record the flight log it would be interesting to see the duration and altitude loss that actually occurred before you recovered once they gave you the rope. It would give us all an idea of what a recovery interval is from a full 90 degree lock out.

I have a hunch you will find it was nothing like you recalled.

Tad Eareckson - 2008/11/30 23:44:38 UTC

Bacil,

I'm gonna cut you some slack 'cause you don't tow but...

If I were standing soaking wet in a freezing downpour and Jim were to say, "It's raining.", I would remove my hat, look at the sky, and turn both palms upward.

Anybody who would trust Jim's statements on ANYTHING at this point hasn't been paying attention.

You gotta be REAL careful with that "Obvious" word in this aerotowing game 'cause lotsa stuff that seems so is, in fact, pure crap. Much of what Messieurs Pagen and Bryden wrote on the issue that seems obvious is pure crap.

Short story...

Gliders don't kill tugs - especially Dragonflies. Gliders mostly kill themselves and are all but incapable of killing tugs. A tug, on the other hand, is upon rare occasions capable of killing the glider.

Jim has no useful understanding of weak links.

Somebody once told him that a single loop of 130 pound Greenspot, regardless of the bridle configuration, translates to 1 G for any and every solo glider regardless of its weight. That "fact" was burned into his circuitry on Day 1 and there is no way he can be reprogrammed.

He fails to understand that:
- if he's packing a 450 pound weak link up front it's completely irrelevant what's on the back end of the line once that figure is exceeded.
- a 500 pound weak link on a solo is no more dangerous to the tug than the same thing on a tandem.
- weak link strength is completely irrelevant to any discussion regarding control of either plane.

None of that will ever change either.

For all intents and purposes - only the first ten or fifteen seconds of the tow are dangerous to either party and there are only about three and a half things the glider can do to the tug.

He can pull the tail left, right, or up.

He can't pull the tail down 'cause the runway's there to stop him for a good while after launch - so he can't stall the tug.

He can pull the tail left or right but - what the fuck - who cares?

Most importantly - he can pull the tail up and nose the tug into the ground - and, take note here, NO WEAK LINK CAN PREVENT HIM FROM DOING SO - but:

he's on the other end of a 250 foot line so he can't pull the tail up very fast; and

the tug pilot is REQUIRED to have his finger on the trigger so there's a pretty easy remedy anyway.

The only other thing the glider can do to the tug is to increase drag by abruptly stalling, locking out, or lawn darting and the weak link WILL protect the tug if neither pilot takes other appropriate action. (Note: There's no telling what the glider will end up looking like after the weak link kicks in at that altitude.)

The scenarios in which Jim's cut 'em all loose and let God sort 'em out later cure-all approach can kill people...

glider is mushing (Bill and Mike), tip stalled (Danny), oscillating (Holly, Bob), locking out but climbing (John Dullahan).

In only one of these instances - Bill and Mike - was the tug's safety being compromised and, in that case, not until things had been allowed to deteriorate for a long time and into the point of no return.

USHGA Tug Pilot Guidelines

Under certain circumstances giving the towed glider the rope may worsen their predicament. If possible, without significantly jeopardizing your situation, attempt to maneuver the tow plane in front of the glider so as to allow the glider to gain enough altitude to set up a safe landing.

http://www.chgpa.org/forums/viewtopic.php?f=2&t=2467
weak links

Jim Rooney - 2007/08/01 13:47:23 UTC

Here we go again with more of the "you're better on tow in a bad situation" BS.

If you wanna see how much abuse even a wimpy trike can take without breaking a sweat...

http://www.youtube.com/watch?v=F_n5B3-MIC4


Anecdotal... Find me a single incident of a tug fucked over by a glider.
---
I'll be responding to:

http://www.chgpa.org/forums/viewtopic.php?f=2&t=3648
Oh no! more on weak links

and any other spinoff topic here to keep things from getting fragmented.
---

Carlos Weill - 2008/11/30 19:24:09 UTC

(See original above.)

Carlos,

Thanks much for the invaluable first hand account. Forgive me though for taking some issue with your lessons learned.

...my body was off centered and could not reach the release.

USHPA SOP 12-02.10:B:6

A release must be placed at the hang glider end of the tow line within easy reach of the pilot.

Mistake #:
- 1: Failure to comply with regulations governing FAA Tow Exemption #4144.
- 2: Continued failure to comply with regulations governing FAA Tow Exemption #4144.
- 3: No more - the rest can be written off as shit happens.

Dan,

I DO have a three second interval recording which includes a really cool lockout in which the altitude loss is thirty feet. That's more than enough to get you killed if your starting altitude is twenty-five feet.

P.S. I believe that, by 90 degrees, Carlos was referring to heading - not roll.

Lauren,

The weak link Tad gave Paul did not break under pressure that was so violent that it broke the TUG'S weak link. It was a pretty scary incident. (Sometimes regular weak links do not break when they should, either. However, the very first time this particular link should have broken it failed to do so...)

The weak link Jim gave Carlos did not break under pressure that was so violent that it broke the TUG'S weak link. It was a pretty scary incident. (Sometimes regular weak links do not break when they should. The very first time this particular link should have broken it failed to do so.)

I heard a snap, and then just like the sound of a WWII plane just shut down hurdling to the ground, only the ball of fire was missing. The tug weak link broke off at 1000ft, in less than a second the glider was at 500ft.

So, again, I'm STILL having a hard time understanding how the Evil Tad Weak Link was more inconvenient, unreliable, scary, dangerous than the Miraculous Jim Weak Link. Can you tune me in?

Janni,

Yeah, that was tension - versus speed - controlled towing. About the only way a weak link can come into play in that environment is if something jams or locks up.

No, Tad's one of the very few people who DOESN'T have these two mixed up (as recently acknowledged by Donnell Hewett).

Still waiting for your response regarding Jim's agreement with me that by going under 1 G you're asking for trouble. Take your time, make it good.