MikeLake wrote:Actually Zack it does make a difference as can clearly be seen from Mike B's video.
Didn't say it didn't make a difference...just that the difference didn't appear to be that critical. =) But I didn't consider the line catching something and will certainly defer to your expertise on this.
Mike got in ahead of me (Hi Mike) and said some of what I had already written but I'm gonna post it anyway 'cause I already had it written.
---
It's just a still frame extracted from the video...about 4 seconds in.
Undoubtedly the same one he has up at The Davis Show now.
Don't they normally attach two stage releases at the waist?
No. Not if they have any brains anyway.
The purpose of a two stage is to allow you to start out in aero mode and finish up in platform mode.
- In aero the obvious, common sense, technically sound thing to do is pull from your shoulders - and it's best to have the tow tension split between you and the wing so that the line of thrust is aligned reasonably well with the centers of mass and drag of the glider (defined as you and the wing) and the wing doesn't get left behind you.
However... You COULD anchor an aero bridle at your hips and run it through guide rings at your shoulders to keep things from getting messy (but not unworkable) and the effect would be the same. But that would be stupid and pointless. EXACTLY the same stupid and pointless way for platform you can run a bridle through guides at your hips and on up to the carabiner and achieve an identical effect (speaking of Gregg Ludwig).
To take stupid and pointless a step further... You could route an aero bridle through guide rings at your shoulders, back through guide rings at your hips, and up to the carabiner. The effect would be the same - but it WOULD illustrate that, no matter how you rig things, ALL of the tow tension is being transmitted to the hang point. And that's a concept that Donnell never got.
But anyway...
- In platform it's BEST to be pulling from your hips / body's center of mass / harness's suspension/rotation point. That way the line of thrust - which is going through the centers of mass and drag 'cause it doesn't have a choice - isn't putting any head up or down torque on you.
- Your chest is a pretty good compromise between aero and platform points.
Upsides:
- At low tow angles it's gonna be indistinguishable from one point aero off the shoulders. (And the shoulders aren't really the shoulders anyway. AT loops are installed on your upper chest where the shoulder straps join the body of the harness. And the Koch release rotates forward on its mountings when the pull is forward.)
- The actuation levers are about as easily accessible and operable as anything you're gonna get that's not on the basetube.
- The farther aft on your harness you mount a two stage the:
-- lower the tow angle - read altitude - at which you're gonna start having interference with the basetube and needing to take a hand off the basetube to do something about it (do I need to elaborate here?)
-- more crap you're gonna have whipping over your basetube and trying to figure out how to tie a knot to something when you blow the first stage.
Downsides:
- Maybe you have a significant head down torque issue at high tow angles but a thin pitch limiter cord on or installed on your harness makes that a non issue.
- It's gonna be more difficult to access your parachute but your odds of living if you're stupid enough to get into a tow situation in which you need a parachute ain't all that great anyway.
Yeah, you really lost me when you said he was.
Call me on stuff like that so I don't look AS stupid for AS long.
New component for the Kite Strings mission statement:
What will keep Kite Strings from becoming another Bob Show?
You will ... hopefully. The price of freedom is eternal vigilance. Everyone has to do his part once in a while. If you see something that's not being done correctly, then it's your duty to speak out. One big difference between the Kite Strings and The Bob Show is that the Kite Strings really does honor the free speech of its members.
I said that because I remembered Gregg configured his this way...
Yeah. Gregg.
...but then I watched a vid I made of someone from the UK foot launching...
Yeah.
Yikes
I had to move because I was worried I'd get hit.
Foot launching.
The release is clearly at his shoulders, consistent with what Mike Lake said.
And let's not forget that Mike was the first person to develop surface (which was all there was in the early Eighties) tow equipment which kept tension off the basetube and that the Lake Bridle was the immediate predecessor to the Koch two stage.
However, Gregg and Mike B's vids show it can be done from the waist, so it doesn't appear to be that critical.
Yeah.
And the first of Mike Bomstad's (Miller Stroud's) vids:
shows that seven out of eight times it's not that critical for the "pilot" and "crew" to verify that the "pilot" is hooked in at the beginning of the launch sequence.
And in the second of Mike Bomstad's (Miller Stroud's) vids:
There's an AMAZING amount of stuff in hang gliding that doesn't appear to be that critical - and almost always isn't. That's how come just about everybody in hang gliding just keeps rolling dice instead of figuring out how to do things right and doing them that way.
The bridle was the weak link. Are you saying he should have been using a lighter weak link? At what point in the video do you think it would have been good for him to have a weak link break? What weak link breaking strength would be required to ensure it broke at that point?
Just as a weak link cannot prevent lockouts, a weak link cannot prevent high pitch attitudes either, as towline tension is not a function of how dangerous your attitude is. Assuming no change from the tow operator, the best outcome for the pilot in this scenario would have been remaining on the line until he had more altitude (a choice his 'weak link' took from him).
The "purpose" of a weaklink is to increase the safety of the towing operation. PERIOD.
You're just never gonna get this concept, are ya Zack?
Mike Bomstad - 2011/12/28 00:14:17 UTC
They used split bridle & attached both to the shoulder points rather then the waist......
When he released the first one (Over the bar) that leaves the other under the bar ( pulling you down @ your shoulder... ie pulling you aft
Bullshit. The tow angle is constantly increasing from launch to top-out and if the pilot does his job the shift to stage two is imperceptible to anyone on the ground without a good pair of binoculars.
Surface tows require you to be attached at the waist area. NEVER @ the shoulder.
I agree also. This logic is why we chose to use "strong" weak links when we were training the monsterwinch operators. Normal weak links would have been blasting away all day, and no meaningful training would have taken place because all our time would have been exhausted chasing ropes and reloading for the next low blow.
You mean like at ANY aerotow operation?
The test pilot should be aware that his weak link is really not that weak, and be prepared to take appropriate actions at the right time during the tow.
Whereas regular pilots should just lay back and wait for their "normal" weak links to break before they can get into too much trouble?
Steve Davy - 2011/12/28 11:17:59 UTC
Please define "strong" and "normal" weak links. Preferably in G's- (Lbs. or Kg.) Thanks.
NOOOOO!!! Don't give them the opportunity to start talking pounds. Hold them to Gs. (I kinda like Cloud Hopper so don't rough him up any more than necessary.)
P.S. If you could convert those numbers to towline that would be even better.
Most of your surface towers have all the tension going directly through the weak link.
Brad Gryder - 2011/12/28 11:40:16 UTC
I'll try to get you a more quantitative answer later (schedule too tight this AM), but in the real-world context of what I described, which occurred over 20 years ago, we used mason's twine for our pseudo weak links. Sometimes one loop, most of the time two, and when test piloting for a lead-footed winch trainee we'd use three loops sometimes.
And how many loops would you use for a good pilot with a good winch operator flying in strong thermal conditions conditions in which he might suddenly find himself standing on his tail with the winch disabled by a line dig?
Real World Definitions:
Normal Weak Link: A weak link which is sufficiently weak to provide a high degree of confidence to the pilot that it will blow before the wing fails.
So about three Gs?
"Strong" Weak Link: A link that is so strong that the pilot's heartbeat exceeds 200 bpm and the wing's fabric looks like an overripe tomato prior to failure.
So about five Gs?
Mike Lake - 2011/12/28 12:11:54 UTC
They used split bridle & attached both to the shoulder points rather then the waist......
When he released the first one (Over the bar) that leaves the other under the bar ( pulling you down @ your shoulder... ie pulling you aft
Surface tows require you to be attached at the waist area. NEVER @ the shoulder.
With respect, the above remark is nonsense.
And since when did this asshole start meriting respect?
Surface towing must include foot launching so that particular piece of advice is actually quite dangerous.
Not necessarily, but either way...
You fly the 'over' line to a point where it needs to go under then you release it, regardless of the attachment point.
Foot launching with the line attached to the hip area ensures the top line is interfering with the base bar almost immediately on takeoff, just when you don't want it to.
As for the video.
It is no harder to make a bridle that doesn't break than it is a pair of side wires.
It's actually a lot easier. You can get really small diameter high tech stuff from these sailboat places that's unbelievably brutal.
Oh, I've heard the "everything we do is an experiment" line before.
The trouble is, it's not.
I've seen experimentation with towing gear more than anything else in HG.
Go forth and experiment. That's great... that's how we improve things.
I'm just warning you of that chasm.
A few years ago, I started refusing to tow people with home made gear.
I like the idea of improving gear, but the lack of appreciation for the world they were stepping into didn't sit with me.
For example... flying with the new gear in mid day conditions?
Are you kidding me????
Approach it for what it is... completely untested and very experimental gear which will likely fail in new and unforseen ways as it tries it's damndest to kill you... and then we can talk.
These motherfuckers won't let anything other than the s**t equipment they sell get off the ground.
Make no mistake what nearly killed the pilot was the glider becoming detached from the towline near the ground.
What saved him was that he actually missed the ground.
It is clear to see that in this instance a line break, a premature release or a bridle failure a few seconds earlier would have killed or seriously injured the pilot.
A FEW seconds? I think he'd have been toast with at the most one or two fewer by way of margin.
Most would agree, it is essential to rigorously check all equipment to reduce this risk to an absolute minimum. Walking the line, examining the attachment points, replacing worn webbing, fittings etc. all necessary.
Harry Robb - 1975/09
Polyethylene or polypropylene, 12 strand, braided 3/8 inch line, 500 feet in length is used in competition. Lines for novice flyers should be about 150 feet long, and increased in length as experience is gained. According to the Kiting Handbook ((Manned Kiting)) by Dan Poynter, this size line has a tensile strength of 2025 pounds. Each end of the tow line is normally provided with a stainless steel screw-pin shackle with an approximate 3/16 inch shank which fits in the slot of the safety release hook. The screw pin of the shackle is inserted through a loop of the tow line at least 2 or 3 feet, providing sufficient friction to prevent disengagement. Although some flyers use only the loop of the tow line in the safety release, this practice is not recommended as it greatly accelerates the abrasion and fraying of the line. Once the line shows very many single strand breaks, its tensile strength is greatly decreased and should be discarded. No flight should ever be made with a knot in the tow line. Aside from the abrasion caused by the knot rubbing on itself, the tensile strength is decreased by as much as 50%. Lines require constant inspection - prior to the first flight of every day by every flyer. In a tournament, the Lineman Starter can inspect some portions of the line on each flight, and the Safety Inspector will inspect the entire line slowly, foot-by-foot, two or three times daily. The tow line is a life line and must be treated with utmost respect.
Except of course some then introduce a weak-link designed to keep you teetering on the edge of this disaster mode every time you fly, in effect making the above checks almost a waste of time.
Andrew Stakhov - 2011/12/28 16:36:12 UTC
From what my friend told me it happened when he went to transition. For those of you who don't static tow, this type of bridle has a Y shape, split into two segments. The short one goes over your basebar and is the one carrying the load when launching. As you get higher, the angle of the rope starts pushing down on your basebar. This is where you hit a switch on your release mechanism which drops the top bridle, and moves the preasure to the second rope segment which is attached under the basebar. This "jerk" causes abrupt preasure on the line, and is the most common time when you get a weaklink, line, or bridle break. I don't know why the weaklink failed in this case, or whether they forgot to use it, but the way he described it the bridle loop itself broke apart when he transitioned. I'll ask my friend next time I see him for details and maybe copy of the original video.
- Whatever it was that failed did so for one reason and one reason only - it wasn't up to the job. If we can design hang gliders such that the leading edges and cross spars blow before the sidewires we can construct and maintain tow system components which don't blow when the glider isn't under any stress whatsoever.
- Yeah, get the video showing the rest of the flight up. I wanna see just how close he came to getting killed because of a worn out length of towline.
Craig Hassan - 2011/12/28 17:04:51 UTC
Launching from a cart you can go one bridle under the bar...
It's a towline - not a bridle. (But at least you spelled it right.)
...and attach it to the shoulders.
Yeah, you CAN. That don't necessarily make it a great idea.
No harm done.
Most of the time.
The glider will tow at "trim" unless either the pilot or the tow line pushes or pulls on the control bar.
- No, it'll nose up beyond trim 'cause the towline IS pulling on the basetube during the most dangerous part of the tow and you'll need to use some muscle to keep it at trim until you gut some tow angle.
- Did you ever try to push a basetube with a towline?
The only downfall to having the line run to the shoulders is getting pulled head down.
And only when the tow angle gets significant.
A single point harness will go so far head down you can't reach the bar above and behind you.
Has anyone actually experienced this? The torque is gradually worsening with tow angle and I'm having a hard time imagining anyone allowing things to gradually progress to this far to the south.
A multi line harness will resist the pull a little more, but can easily put your head below the bar. We normally use a limiter line from the 'biner to the shoulders to help stop this.
A normal occurrence, when a line or weak link breaks, is the glider slows...
The glider ALWAYS slows (angle of attack ALWAYS increases) when the tow is lost.
...and the pilot swings forward.
If the tow angle is low and the tension is going to the pilot only he's gonna swing BACK relative to the glider upon a break.
Kind of an automatic correction.
The automatic correction will be, hopefully, the pilot pulling in.
Problem is, as humans when things are not going right we tend to fight. In this case if the pilot knew things were going wrong and his body was trying to swing forward, one could conclude he pushed out.
I couldn't. This guy didn't do a great job by any stretch of the imagination but if he had pushed out he'd have been dead.
This would obviously aggravate the situation.
It would obviously do a helluva lot more than that.
The other situation I can think of is the one I believe.
Me too.
The tow was way too fast. The pilot did not release the upper bridle in time. The line pulled the bar down (pulled in) and the pilot was now flying much faster than trim. Then once the bridle gets released, the glider does what gliders with too much speed do. It instantly noses up, increasing the line force and snapping the second bridle. Due to the excess speed, the nose up is quick and extreme.
Yeah.
As I see it the lesson here is not about the bridle setup and attachment. (Maybe a reason for NOT using an over/under bridle if you don't foot launch.)
No. That's a really solid arrangement and has been for decades.
It is about making sure the tow operator, pilot, crew, everyone knows what the hell they are doing, and has the equipment to do it right!
DEFINITELY.
Was there a line force gauge on the tow vehicle? That would be my first question.
My first question would be, "Was there anyone watching the fuckin' glider?" No, actually, my first question would be, "How come no one was watching the fuckin' glider and why can't you people be bothered to use towline capable of keeping a fuckin' glider climbing when it really needs to be?"
There is an art, or rather, a knack, to flying. The knack lies in learning how to throw yourself at the ground and miss.
--Hitchhiker's Guide to the Galaxy
I fly a sport 2-155-I want to use a 1.5g weak link-max hook in 250-glider 59 -309 total, so I pick a 463.5 lbs link.
Now let's say I hook in at 150, is it accurate to SAY I am using a " 1.5g " weak link ?
'Cause you're very seldom lucky enough to get a flying weight or what you REALLY want - the glider model and size - to go along with it.
Me too, Tom Low...
Thanks. I've been wanting a name to go with that identity for a couple years. Has his head screwed on right or reasonably close on some of these important issues.
Now let's say I hook in at 150, is it accurate to SAY I am using a "1.5g" weak link ?
What's it matter? In hang gliding if you talk about weak links in terms of Gs people just stare at you like you just landed from a distant galaxy.
No, YOU would be using a 2.2 G weak link.
But you could say "I have a 1.5 G weak link for my Sport 2 155." That wouldn't be accurate either unless the glider were maxed out but would be consistent with sailplaning in real aviation in which neither the manufacturer or FAA cares about who's strapping himself into the cockpit or how much water he's using for ballast on any particular day. And "the maximum certificated operating weight" would be assumed by any listener with half a clue or better.
Nah. There's no argument. Rodent, Zack, and Mike Lake have everything under control. Really.
How about not towing when you don't know what the hell you are doing.
Yeah. I'm good with that. Since knowing what the hell you're doing includes knowing what a weak link is and the rating of what you're using, your useless ass is immediately and permanently taken out of the equation.
I don't think it was long before the glider blew up.
Yeah? What the hell are you talking about?
Think he had enough height to throw his chute?
Sure. There's almost always enough height for anybody to throw a chute. I just don't think he'd have survived if he had added that item to the list of other stupid things that were done prior to and in the course of that flight.
Now my turn. Think we'd be talking about how much height he'd need to throw his fuckin' chute if his fuckin' towline hadn't blown up? Five hundred words or less.
Very lucky he walked away from that.
Oh, yeah... Now that you mention it.
FYI one line under attached at the waist works dolly launching.
Yeah, damn near any towing piece o' crap you wanna name WORKS when dolly launching. And most of the pieces of crap - save for 130 pound Greenspot - WORK throughout most tows. But only a total moron will fly with a damaged sidewire 'cause it WORKED the past half dozen flights.
A REAL pilot doesn't ask himself if a particular piece of equipment, component, configuration, or procedure is likely to WORK on any given flight. A REAL pilot asks himself if there's any possibility of being in a situation in which a particular piece of equipment, component, configuration, or procedure WON'T work and if there are better ways of doing things.
And in this particular situation - which happened to arise as a result of operator error on both ends of the line but also could've been precipitated by forces beyond human control - a critical component of the towing system was in shit condition and that guy came almost exactly as close to being killed just as dead as he would have had a frayed sidewire blown at the same altitude.
And none of you assholes really seem to be getting a grip on that concept.
But I didn't consider the line catching something and will certainly defer to your expertise on this.
C'mon Zack...
Tad Eareckson - 2011/11/18 14:07:50 UTC
I don't really want anyone who DOESN'T doubt everything I say participating in this forum.
Don't start deferring to people's expertise unless you're collecting wild mushrooms for dinner for the first time. Our ability to think for ourselves is the only thing standing between civilization and Rooney.
You have ropes sliding side to side on and moving and whipping across pieces of tubing with grips, wheels, VG cleats and cords, instruments, and/or bar mitts mounted on them. Murphy says something bad is gonna happen sooner or later.
I can give you two pilots who had really bad days 'cause they surface towed with two point bridles which stayed in contact with the underside of the basetube at low tow angles.
1984/07/14 in Nova Scotia a student named Andre was static towing behind a van, snagged a bolt used for pontoon mounting, and got very seriously and probably permanently vegged.
1991/06/09 in Michigan Harold Austin, a highly experienced tow pilot who went back to 1968, hooked an axle stub protruding from the left end of his Sport's basetube, and got killed.
And the Lake Bridle and Koch two stage were available for the first and second respectively. But, hey...
Zack C wrote:But I didn't consider the line catching something and will certainly defer to your expertise on this.
Tad Eareckson wrote:Don't start deferring to people's expertise unless you're collecting wild mushrooms for dinner for the first time.
By 'this' I meant whether it was better to tow from the shoulders or waist with a two stage release (not whether line catching could be an issue). I don't have any experience towing with a two stage configuration and
Tad Eareckson wrote:And let's not forget that Mike was the first person to develop surface (which was all there was in the early Eighties) tow equipment which kept tension off the basetube and that the Lake Bridle was the immediate predecessor to the Koch two stage.
If I ever start towing two stage (from the shoulders) and find problems with it, then I can challenge him/you, but you have to start somewhere.
I don't have any experience towing with a two stage configuration...
Zack C - 2011/03/04 05:29:28 UTC
As for platform launching, I was nervous about it when I started doing it. It looked iffy, like things could get bad fast. I've since logged around a hundred platform launches and have seen hundreds more. Never once was there any issue. I now feel platform launching is the safest way to get a hang glider into the air (in the widest range of conditions). You get away from the ground very quickly and don't launch until you have plenty of airspeed and excellent control.
- I don't think you really need any.
- It's just an aerotow which gradually evolves into a platform tow. At some gray area point when convenient you trip a lever to transfer the towline from aero routing to platform routing.
If I ever start towing two stage (from the shoulders) and find problems with it...
It's been universal in Europe for over a quarter century and it's not exactly unheard of on this side of the Atlantic. And it's astonishingly simple. For all intents and purposes there are no problems with it - certainly nothing you're gonna discover and have named in your memory.
I am, however, hoping to hear a report of somebody slamming in as a consequence of a Weghorst before the end of the upcoming season - Bart himself with any luck.
