Weak links

General discussion about the sport of hang gliding
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Tad Eareckson
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Re: Weak links

Post by Tad Eareckson »

http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks
JD Guillemette - 2013/03/11 23:31:56 UTC
Jim Rooney - 2013/03/11 18:59:06 UTC

Now, I pro tow with a 130lb weaklink. I'm 160lbs soaking wet. The protow cuts the force seen by either side of the bridal in 1/2, so I'm overloading the release with over 2X's it's achievable load.
You have the right idea Jim about how much force the realease "sees" but...
- No, he doesn't. There's hardly anything that piece of shit ever says that he DOES have right. You can't check the math yourself and you can't even read somebody like Zack who does your grade school arithmetic for you. The towline tension maxes out at 260, the bridle / weak link / release tension maxes out at 130. 160 over 130 is 1.23 - not 2.00

- You have too many "a"s in "realease".
...lets take it one step further...
No. Stop. You're in way over your head already.
...the achievable tow force load is actually 4x the weaklink strength.
Looking at a secondary weak link on a two point bridle - close enough. But this isn't a two point bridle or a secondary weak link.
We use a single loop of 130lbs...
WHY - asshole? We just killed somebody about your flying weight on and because of a single loop of 130.
...so that is two stands of weak link...
What's a "stand" of weak link?
...in that bridle leg (not one stand), so that is 260lbs of force that leg of the bridle can take.
Maybe if you're stupid enough to still believe the crap they taught you at Ridgely. Otherwise divide by two.
Now as you mention above, each leg of a tow line bridal...
Wrong kind of bridle, dude.
...shares the tow line force equally (similar to how the two weak link stands share the load).
What happens when you bend the line around the parachute pin? Are the fibers on the inside of the curve being loaded/stressed the same as the fibers on the outside of the curve?
Of course there is some losses in cutting effect of the bridle or release on the weaklink, and the angle of the bridal, but a sufficently long bidal reduces the angle losses to nill.
You didn't answer my question.
So it take tkes up to 520lbs of tow line force to break a single loop of 130lbs greenspot in pro tow configuration.
Really?
JD Guillemette - 2008/02/22 17:11:47 UTC

Looks like Tad has been busy in his work shop doing some test to discredit the Bailey release. We might have done a public service keeping him occupied in his work shop and out of public.

Come on Tad lets get reasonable, for the tow forces involved, the curved pin is fine. You had to put 220 lbs of force to get the curved pin to bend/fail. For a "Pro-Tow" configuration (shoulder tow) that would mean 220 lbs of force on each shoulder, so that's 440 lbs on the tow line. For a solo tow ... I doubt it.
That sounds just a wee bit high to me.
- Put a pulley over the edge of a cliff dropping down a bit to a river so nobody gets hurt.
- Have two 260 pound dudes on an outcropping just down from the top ready to get wet.
- Put a glider on a dolly a hundred yards back from the cliff.
- Run a line from a one point bridle on the glider to and through the pulley and down to the dudes.
- When the glider's ready the dudes grab the line and jump.

Does this glider:

http://www.youtube.com/watch?v=MlIGsgNFRWM


look like it's feeling a bit over a quarter ton of thrust at the point its Rooney Link pops?
So our weaklinks are not realy as weak as people would think.
Yeah, they're especially not really as weak as people who've actually put them on load testers would think.
If anyone doubts the math, you can perform a free-body diagram of the weaklink system and simple static engineering analysis will reveal the answer.
You didn't happen to take any of your engineering classes from Dr. Tracy S. Tillman at Eastern Michigan University in Ypsilanti, did you?
It's the same principle that every pully and compound pully employes. The bridle weak link system is a compund pulley.
You don't have a computer capable of running a spell check?
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Tad Eareckson
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Re: Weak links

Post by Tad Eareckson »

http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks
Zack C - 2013/03/11 23:46:10 UTC
JD Guillemette - 2013/03/11 23:31:56 UTC

We use a single loop of 130lbs, so that is two stands of weak link in that bridle leg (not one stand), so that is 260lbs of force that leg of the bridle can take.
As has been pointed out many, many times (including by me five posts ago)...
And Yours Truly, specifically to JD...

http://www.chgpa.org/forums/viewtopic.php?f=2&t=2871
speed link
Tad Eareckson - 2008/01/31 12:55:45 UTC

If you had had a starboard weak link as well, you'd be free flying by now because it fails at 140 pounds and would just have been shock loaded at something well in excess of 280. Instead you're still on tow, you no longer have a weak link on your end of the system, your lockout is getting worse, you have a mechanically inefficient release under up to four times as much load as it has ever experienced in the course of your flying career.
...over five years ago.
...this is incorrect.
Well yeah, but if you get enough things wrong all at the same time...
Quest Air

A good rule of thumb for the optimum strength is one G, or in other words, equal to the total wing load of the glider. Most flight parks use 130 lb. braided Dacron line, so that one loop (which is the equivalent to two strands) is about 260 lb. strong - about the average wing load of a single pilot on a typical glider.
...sometimes they can do a reasonably good job of canceling each other out.
Quest, Lookout, Billo, Towing Aloft, TowMeUp, and two people I know with load testers have all confirmed that two strands of 130 breaks around 130 lbs. Thus, 130 lb weak links in 'pro tow' configurations allow a towline tension of around 260 lbs. In a two (three) point configuration, such weak links allow line tensions around 225 lbs (due to the larger bridle apex angle).
JD Guillemette - 2013/03/11 23:55:59 UTC

Zack,

Unfortunately your wrong, if you don't believe me do the proper engineering analysis.

Each strand of the weaklink will see 1/4 the tow line force, just like how Jim points out the each line of the bridle see's 1/2 the tow line force.
Not a good idea to keep citing Jim Keen-Intellect Rooney as a reference. He's gotten to that point in his life at which he can't utter three sentences without blatantly contradicting fifteen other points he's made on the record.
It's simple math and static analysis. It's how a pully works.
It's EXTREMELY simple if you fail to question your foundational assumptions (Donnell).
Maybe 130lbs weaklink breaks well belopw 130lbs, or there higher cutting forces of the weaklink attached to the bridle, but math is math.
You haven't done all the math you need to.
Deltaman - 2013/03/12 00:05:16 UTC

Hopefully, Zack is perfectly right.
Zack C - 2013/03/11 23:46:10 UTC

two strands of 130 breaks around 130 lbs. Thus, 130 lb weak links in 'pro tow' configurations allow a towline tension of around 260 lbs.
Before to use math you have to test a loop (2 strands) of 130lb
Zack C - 2013/03/12 00:14:12
JD Guillemette - 2013/03/11 23:55:59 UTC

Maybe 130lbs weaklink breaks well belopw 130lbs, or there higher cutting forces of the weaklink attached to the bridle, but math is math.
I'm not disputing what they break at in theory. I'm telling you what they break at in reality.
If the reality doesn't match the theory, the theory is wrong.
You're not disagreeing with me. You're disagreeing with the experimental results of Quest, Lookout, Billo, Towing Aloft, TowMeUp, and two people I know with load testers.
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Tad Eareckson
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Re: Weak links

Post by Tad Eareckson »

http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks
William Olive - 2013/03/12 00:18:07 UTC
Tormod Helgesen - 2013/03/11 20:36:21 UTC

Thanks Jim, I knew there must be a reason why the straight pin isn't much used, just didn't know what.
Plenty of us use straight pin releases. I prefer them for a number of reasons. They are less prone to high release pressure...
What's that mean? They won't release under high PRESSURE?

Can't you just use a...

http://www.hanggliding.org/viewtopic.php?t=21033
barrels release without any tension except weight of rope..
Bart Weghorst - 2011/02/25 19:06:26 UTC

I've had it once where the pin had bent inside the barrel from excessive tow force. My weaklink was still intact. The tug pilot's weaklink broke so I had the rope. I had to use two hands to get the pin out of the barrel.

No stress because I was high.
...Bailey or...

http://www.hanggliding.org/viewtopic.php?t=22540
LMFP release dysfunction
Diev Hart - 2011/07/14 17:19:12 UTC

I have had issues with them releasing under load. So I don't try to release it under a lot of load now.
...Lockout Mountain Flight Park release if that's your goal?
...they are far less likely to release by being caught on the base bar when you pull in, the thin rope it's made of...
What do you mean - "IT'S" made of? You've never checked out any of MY barrel releases.
...isn't overly strong...
Oh. That's a GOOD thing? So's you can skip using a weak link and have your barrel release tear itself apart if need be? Is this one of Bobby Fucking-Genius Bailey's designs? Do you get a couple free with each Dragonfly purchase?
...and most important for me, they're what is sold around here.
Yeah, that's always a HUGE issue in mission critical aviation equipment.
Wanna say anything about load capacity? Just kidding.
As a general comment, I couldn't care less if you use a bent pin release...
I'm sure you couldn't - just the way none of you assholes couldn't have cared less about the crap Robin got in line with.
...or a ring and pin or a linkknife...they all work well if they are in good order and set up properly, and they get no argument from me.
Wanna say anything about load capacity, ability to maintain control during actuation, fatality history? Just kidding.
Perhaps deltaman's release will work fine too, but I don't know coz I haven't seen it yet.
But you've seen Bailey Bent Pins and - even though we've got tons of reports of them being completely inaccessible during lockouts and welding themselves shut under load - you're totally cool with them. Because you've SEEN them.
Strangely enough I do get a a little peeved when people tell me I'm an idiot for using the gear I use.
Don't worry, Billo. I'm not gonna tell you you're an idiot - and interfere with the job you're doing in the course of this post.
It's that religious zealot thing...
It's a PHYSICS zealot thing.
...the "One True Path".
- What's the procedure for recovering from a stall?
- Describe the differences between Wills Wing and Moyes VG systems.
- Where's the best place to install a leading edge spar?
- If you're standing on the edge of a cliff when's the best time to make sure you're connected to your glider?
- Never mind, if one of you Aussie assholes is in a harness you're - by definition - connected to the nearest glider.

Hang Gliding Fail
http://www.youtube.com/watch?v=2mX2HNwVr9g
andyh0p - 2011/04/24
dead

Image
Image
Image
There are several ways to skin the towing cat safely...
There are TONS of ways to skin the towing cat and GET AWAY WITH towing for tens or hundreds of thousands of tows - but if you give Murphy an opening or two you can COUNT ON him rearing his ugly head once in a while. And that's EXACTLY what happened to ex pro toad Rooney Linker Zack Marzec in that inexplicable freak accident at Quest at the beginning of last month.
...and I'm open to ideas...
When was the last time there was a new idea in any flavor of sailplane towing? If this sport weren't the corrupt idiot shit hole it is we'd have run out of ideas for towing hang gliders thirty years ago. Notice that the gliders themselves haven't changed all that much since the end of 1979.
...just don't get in my face and tell me I'm a fool, which was Tad's modus operandi.
At least I'm consistent, dude.
BTW, in my personal experience, I have had a WL break where the release rope has then wrapped around the tow rope ring.
WHY did you have a weak link break? Or - even after what just happened to Zack Marzec - is a weak link break still a nonevent?
The release broke off before the tug end WL went, which meant that I had to buy a new release.
WHY THE FUCK DIDN'T YOU HAVE A WEAK LINK INSTALLED *BELOW* THE TOW RING AS WELL?

- You have a secondary release down there - so why do you think you won't need weak link protection as wellL? If you had a functional brain it might occur to you that that's the point at which you're likely to need a weak link like at no other time.
I was not unhappy with this, I am attached to that rope and it sure doesn't need to be strong enough to tie up the Queen Mary, just a bit stronger than the WL will do me fine.
I lied. You're an incredible fucking idiot.

http://ozreport.com/forum/viewtopic.php?t=24994
No-knot weak links
Steve Davy - 2011/09/01 01:03:57 UTC

~18. Construction - Shear Links
#01. Objective
A properly constructed Shear Link will maintain its integrity to its breaking point, failing instantly and cleanly.

http://www.energykitesystems.net/Lift/hgh/TadEareckson/mousetraps.pdf
http://www.flickr.com/photos/aerotowrelease/8306429930/
Image
William Olive - 2011/09/01 01:22:08 UTC

Don't bother going there until you have used them.
This isn't a new idea. We used shear links in the past, and there's a reason we don't use them now.
String links work. String links fail safe (ie anything that degrades them makes them weaker).
Yeah Billo, don't even THINK about Tad's Shear Links (which you didn't bother to check out and confused with some other idiot crap you used). A barrel release makes a MUCH better weak link than any concept Tad could possibly come up with.
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Tad Eareckson
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Re: Weak links

Post by Tad Eareckson »

http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks
JD Guillemette - 2013/03/12 00:32:50 UTC
Deltaman - 2013/03/12 00:05:16 UTC

Before to use math you have to test a loop (2 strands) of 130lb
Zack,

You agree that each leg of the bridle splits the tow force so each leg "sees" 1/2 the tow line force.

So the configuration of the weak link is eactly the same as the bridle, so each leg (or strand) of the weaklink will see 1/2 of that side of the bridles tow force.

1/2 of 1/2 is 1/4.

Now what I suspect what maybe happening here is that the method of weakllink attachment may not be allowing the two strands of weaklink to balance out.
Rubbish. What you SHOULD be suspecting is that it's physically impossible for a thread, string, cord, line, rope bending around a sharp curve to maintain anything close to the strength for which it's rated by testing it straight with the ends held fast in Chinese finger trap type devices.
The bridle slips through a metal ring so each leg of the bridle will alwyas be equal.

If the weaklink attachment binds and doesn't allow the two stands to "balance the load" one breaks, then the other in a cascade effect.
A loop of 130 installed on a typical spectra bridle blows at around 130 now matter how the hell you configure it.
I fly with standard pro tow...
I'll bet you're a lot better at holding the nose down than the late Zack Marzec was.
...with release on both sides.
So...

http://www.chgpa.org/forums/viewtopic.php?f=2&t=3391
More on Zapata and weak link
Paul Tjaden - 2008/07/22 04:32:22 UTC

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.
...your chances to release in a lockout should be twice what Paul's were.
The bridle has one weaklink attached with double larks head knot.
Releases on both ends, weak link on one end. Good thinking.
I attached the weaklink to the relaease on my left (simple pin through the loop). The weak link can balance the load becasue it can slip around the pin in the release and so the laod is balanced.

A lot of people don't use the release on the weak link side of the bridle and istead the use another double larks head knot (or single, more on that) to attach to the webbing tab on the harness.
We refer to those people as idiots. Great job, Ridgely, turning them out at the rate you've managed to over the course of the past fourteen seasons.
This will not allow the loads on the two weaklink strands to equlaize and in actuality only one strand is loaded and the other is (in lack of a better word) standby.
Right. One strand is fully loaded while the other is totally slack and shares none of the load whatsoever.
so the one breaks, then the other. So what may look like two stands is only one, and so it breaks at the load of only one strand.
Rubbish. If that were true virtually no gliders so configured would survive dolly acceleration.
Now if a single larks head is used some people would suggest, and I agree, that the knot reduces the weaklink strength.
But perish the thought that we should put anything on a load tester and find out what's ACTUALLY going on - because any numbers so derived would have no external validity.
So by having a "non-binding" weaklink attachment you can greatly increase it's usable load.
Why would ANYONE want to INCREASE it's usable load? The weaker they are...

http://ozreport.com/forum/viewtopic.php?t=24994
No-knot weak links
William Olive - 2011/09/01 01:22:08 UTC

String links work. String links fail safe (ie anything that degrades them makes them weaker).
...the safer they are. If you increase the usable load they won't as clearly provide protection from excessive angles of attack, high bank turns, and the like for that form of towing.
This probably why I don't break many weaklinks.
Yeah JD, you don't break nearly as many weak links as those of us who've bench tested them and found them to blow at 130.
Zack C - 2013/03/12 00:42:04 UTC
William Olive - 2013/03/12 00:18:07 UTC

BTW, in my personal experience, I have had a WL break where the release rope has then wrapped around the tow rope ring. The release broke off before the tug end WL went, which meant that I had to buy a new release.
This is why, as I mentioned earlier, it's wise to have weak links on both shoulders.
Oops. In my previous post I was envisioning a two point tow. I forgot how dedicated all these assholes are to optimizing their one point "release ropes" for the same failure rates they're able to achieve for amateur tow configuration.
If you're towing two (three) point, release from the keel (whether due to a manual release or weak link break), and the bridle wraps on the tow ring, one of the shoulder weak links will most likely break (certainly if they're calibrated to be slightly stronger than half the top weak link's strength). If the shoulder bridle wraps after a shoulder release/weak link break, the weak link on the other shoulder will most likely break.

That said, shoulder bridles can be made short enough that wraps are impossible (this will require moving shoulder releases forward, which I find makes them easier to grab).
And, of course, the percentage of people reading this who'll modify their equipment to eliminate this failure mode will be ZERO. And, some years down the road, WHEN a one point bridle wrap has some really ugly results there will be the usual moronic discussion which will go on for twenty pages until Davis senses progress being made and locks it down.
Keel bridles will always be long enough to wrap, but the chance of this can be minimized by using a stiffer bridle material.
That's ridiculous.

http://ozreport.com/9.098
The thin 1500 pound aerotow bridle
Davis Straub - 2005/05/03

What do you need a 4000 pound bridle for?

Diver Bob Maloney came up with another invention. I unfortunately lost the pictures of his very slick bridles, but he has created two aerotow bridles from Spectra and Vectran lines in thicknesses used for shroud lines on parachutes. The Spectra lines are very thin but can handle 750 pounds. You put a weaklink on that that can handle 200 pounds (about). Why do you need a stronger bridle line? So far there is very little wear on the bridle line.

Bob uses Vectran for the three point bridle. The Vectran leg goes to the keel. Vectran is used because it can handle the heat generated when the Sepctra line on the shoulders is released and slides through the loop at the end of the Vectran.

Bob's aerotow shoulder-only bridles costs $8. The three point bridle costs $15. You'll also need to get a barrel release (http://www.questairforce.com) and either the larger or smaller one with work fine. I use the larger one.

Bob Lane said that Quest Air sold over 40 of their bridles (and Bob sold 15 or 20) during the Nationals. The Quest Air bridles use thicker Spectra and are designed not to whip around and accidentally tie themselves to the carabineer. Bob says his bridles will not do this either.

It is great to see these safer, simpler, and easy to use aerotow bridles becoming popular.
Diver Bob Maloney says thin ones can't wrap and Davis says they're safer and simpler and easy to use. Why would any sane person use a thick bridle that's more dangerous and complex and hard to use?
JD Guillemette - 2013/03/12 00:48:46 UTC

And for the reasons mentioned above by Zack ... that is why I have a release on both sides. If my primary (right shoulder) wraps the tow line, either the weaklink breaks or I can release.

But I can see Zacks point that if my weaklink breaks (left side), and it wraps the tow line, I would have to release the right ... because I don't have a weaklink there.
- If you don't have a weak link there, what's limiting the load on that release and what makes you think you're gonna be able to blow it?
- Why the hell don't you just put a goddam weak link there, shut the fuck up, and go flying?
Good Point.
Idiot.
Zack C - 2013/03/12 01:12:26 UTC

JD,

The load tests that I've seen had one end of the weak link attached to a Spectra bridle (as in flight) and the other attached to a ring that allows the strands to be evenly loaded. In almost all cases, the weak link broke at one of the two places it exited the bridle. Weak links I've broken in flight have always broken at the bridle as well. The bridle attachment appears to be the weak point.

Tests were performed attaching the weak link to the bridle using single and double lark's heads in addition to the 'wrap and tie' method and no significant variance in breaking strength between these methods was found.
What do you expect us to believe? Your little post about actual bench test results here or the fourteen pages of crap by aerotow professionals published in the magazine last June?
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Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Weak links

Post by Tad Eareckson »

http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks
Deltaman - 2013/03/12 01:23:42 UTC
William Olive - 2013/03/12 00:18:07 UTC

Plenty of us use straight pin releases. (..)
The release broke off before the tug end WL went, which meant that I had to buy a new release.
Billo, would you show me a pic from your release please.
Yeah, should be good for a few laughs.
Here was my old one before I start to use mouth release.
400lb load on the release is required before the pin begins to be bent.

http://img818.imageshack.us/img818/407/p1020385u.jpg
Image
Bill Cummings - 2013/03/12 01:28:08 UTC

Two of you are really confusing me.
You were terminally confused decades before this discussion began.
I have some green spot here but I have never see a spool of the stuff yet.
Consider yourself blessed.
When you read the side of the spool what does it say the breaking strength is? (Cortland green spot)
130.00000 pounds. Precisely the right fishing line for a universal standard aerotow weak link.
Zack C - 2013/03/12 01:38:24 UTC

It's available in a variety of strengths, but the one most people...
...are brainwashed or forced to...
...use is 130 lbs.

When I say '130 lb weak link', I mean tied from 130 lb test line.

'Greenspot' is available in black as well.
And, given what it just did to Jack Marzec, I think it would be a good idea for everyone to switch to that color for a respectful period.
JD Guillemette - 2013/03/12 01:38:35 UTC

That's odd, mine always break at the loop side as if it cut at the loop so I have two equal length dead ends attached at the bridle. I always attributed this to abrasion as it works back and forth over the pin. When the weak link discolors and looks "polished" at the loop I replace them.
How do you know they're not just getting more ideal for your flying weight?
Like I mentioned I use a double larks head on the bridle, which may make a difference.
But don't bother testing it to find out.
I alos don't think I use spectra, my bridle is much thicker than the stuff I seen other guy use.
Get Davis to fix you up.
A lot has to do with bend radius and maybe the spectra is so thin it it's not such "bent" around bridle and is kinked around the bridle like a bad knot.
The larger the bridle material diameter the BETTER the strength you're gonna get out of your stupid fishing line.
Zack C - 2013/03/12 01:47:21 UTC

Yeah, the bridle material is significant, which is why I usually include 'on a Spectra bridle' when citing breaking strength test results (although diameter may be more important, as you suggest).

The weak links that I've broken have all been attached to Spectra bridles using a double lark's head or wrap-and-tie and engaging a spinnaker or Lookout (newer type) release.
Davis Straub - 2013/03/12 02:18:14 UTC

Civility begins to rear its pretty head.
Which is always a bad sign when scumbags like you and Rooney have yet to be dealt with.
Jim Rooney - 2013/03/12 05:55:11 UTC

I stand corrected... You're right... You did say 130 breaks at 130.
I have you confused with someone else I think.
Yeah? Who in this discussion has cited anything under 130?
My point still stands... That weaklink is going to break before I encounter loads capable of bending that pin.
Yeah Jim, that weak link is gonna break before a whole shitload of things happen - like, for instance, before a glider gets its climb under control and stabilizes in a monster thermal.
You can try that out as well... Just stick a weaklink in the system.
Unfortunately you won't get a chance to try the release pressures because the weaklink will break as soon as you step on it.
Hard to get a weak link safer than that. Asshole.
Dallas Willis - 2013/03/12 06:23:18 UTC

Unless you fail to seat the barrel all the way. This happened to me in 2008. My report of that flight:

At about 150 feet above the deck...
Plenty of room for recovery from a Rooney Link pop.
...the d-fly hits some kinda ripper on his left side so I begin to brace for it by getting my body to the left corner. I got hit pretty hard but nothing outrageous and found myself facing about 45 degrees off the center-line of tow and the glider didn't seem too terribly interested in coming around. But I wasn't locked out or anything and figured it would straighten out in another couple seconds.

Then *pop* I was off tow. I think hmmm... that wasn't hard enough to break my weak-link but whatever". I got the glider pointed down the runway and a nice gust of wind picked up which made for an easy no-stepper.

The weak-link was brand new that morning (and this was flight #3 for the day) so I had a look at my bridle. It was fine and the weak-link was still attached but my main non-weak-link side release had popped open.
Why do you HAVE a non weak link side?
A quick look and the reason became obvious. The pin was bent near 90 degrees and the barrel had begun to crack. We believe that the barrel wasn't seated all the way forward on the bridle which allowed the bridle to pull on the pin at an angle apparently with some pretty significant force!
Here's a STRAIGHT pin barrel release with the barrel not seated all the way forward, loaded to four hundred pounds pounds - a bit over triple what a single loop of 130 pound Greenspot will do, and still easily operable with less than a twenty pound pull:

http://www.flickr.com/photos/aerotowrelease/8312399698/
Image

So what sold YOU on the bent pin crap you're using?
But not enough to break the weak link.
Very comforting to know that the bent pin release you're using can blow you off tow at an even SAFER tension than a Marzec Link allows.
Just a strange one off caused by me not seating the barrel completely.
I wouldn't know. I can't get my release to do that.
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Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Weak links

Post by Tad Eareckson »

http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks
Gerry Grossnegger - 2013/03/12 06:48:33 UTC
Zack C - 2013/03/11 21:11:28 UTC

- 2 strands of 130 breaks at 130
- 2 strands of 200 breaks at 200
- 4 strands of 130 breaks at 200
That's Greenspot? With what (stock) diameter of rings at each end?
Why don't you just look up the data in your stupid fucking HPAC Towing Manual?
Zack C - 2013/03/12 13:43:07 UTC
Jim Rooney - 2013/03/12 05:55:11 UTC

My point still stands... That weaklink is going to break before I encounter loads capable of bending that pin.
How 'bout before you encounter loads capable of rendering that piece of crap functionally inoperable...

http://www.chgpa.org/forums/viewtopic.php?f=2&t=3107
I have a tandem rating!!!
Lauren Tjaden - 2008/03/23 22:20:15 UTC

The barrel release wouldn't work because we had too much pressure on it.
... for anyone lucky enough to be able to get a snatch at it in an emergency situation?
Depends on your weak link. 130? Sure. 200? Maybe not.
http://www.hanggliding.org/viewtopic.php?p=225946#225946
Life DOES get so much more complicated when you start having more than one accepted standard.
Gerry Grossnegger - 2013/03/12 06:48:33 UTC

That's Greenspot?
Yes.
With what (stock) diameter of rings at each end?
Davis said of the experiments at Quest:
A dozen or so years into their process of perfecting aerotowing.
Davis Straub - 2005/03/01

We looped one end of a weaklink loop to the loop of a spectra bridle (part of a pro-tow and available here at Quest Air) and the other end to a loop of webbing approximately as thick as the loops that you would find on the shoulders of your harness.
http://ozreport.com/9.049#1
Weaklinks

Billo's setup:
http://ozreport.com/forum/viewtopic.php?p=57659#57659

The guy in our club attached the weak link to a Spectra bridle with a lark's head and engaged a 1/8" quick link. The weak links broke at the bridle.

I don't know any details for the other test setups.
How 'bout the pathetic bullshit Dr. Trisa Tilletti pulled...

http://www.youtube.com/watch?v=TOrYXiAZKjs


...to obscure as much as possible the actual breaking strengths of 130 pound Greenspot weak links in actual towing configurations?
Jim Rooney - 2013/03/12 15:43:02 UTC
Zack C - 2013/03/12 13:43:07 UTC

Depends on your weak link. 130? Sure. 200? Maybe not.
A) Go try it.
What would be the point in testing to see what happens on idiot bent pin Bailey "designed" shit that never had any fucking business being put in the air in the first place?
You want to amp it up to 200?...
Morningside did - well before your idiot buddy so graphically demonstrated they were moving in the right direction.
add whatever weight you need (if any). Put some rocks in a backpack for all I care. This is a dead simple test. Rather than FUD, just do it.
- How 'bout you just fucking doing it? I stopped doing that kinda bullshit after it finally dawned on me that - even with a bunch of sofa cushions piled up - I was getting hurt a lot more than I wanted to be every second or third test fire.

- The way Ridgely has. Except Ridgely gets 260 on their 130 (nobody's using 200). And:

-- we know that because that's what Ridgely grad JD Guillemette has been saying it is.

-- I also note that ace Ridgely tug driver Jim Keen-Intellect Rooney only has a fuckin' clue what a standard aerotow weak link blows at by listening to Zack C - eleven years after the beginning of his Ridgely indoctrination - enough times that it starts dawning on him that it's not 260 or 100 but 130.

-- the reason that Zack C knows it's 130 is because it was actually tested by Houston area truck towers.
B) As I said before, the guys seeking these straight pins are doing so because they want stronger weaklinks.
- Yeah. These insane people who wanna have control of when they stay on and get off of tow and don't wanna die in an inexplicable freak aerotowing accident - like your asshole buddy just did seven weeks ago.

- What:
-- about the guys that would just rather not hafta exert over three times the effort to do the same job?
-- shape are the pins on the barrel releases they're using for tandems and what rating weak link protection is being used for them?
C) Also as I said before, I don't care... the straight pin / bent pin is "issue" is a non issue to me.
Good. The more issues you have lined up to kill yourself - or, failing that, your friends and people stupid enough to be listening to you - the happier I am.
Use either. You like straight pins? BFD... use straight ones.
Just not behind you because...

Sorry, what was the reason you gave regarding being so concerned for Zack's safety that you're refusing to tow him?
D) See A)
Pigfucker.
Freedomspyder - 2013/03/12 17:13:39 UTC
Freedomspyder - 2013/03/11 22:17:18 UTC

Davis, I was wondering who manufactures the releases for sale on your site? Sorry if you replied already. I didn't see it...
Your honor... the defendant was unresponsive.
Davis Straub - 2013/03/12 17:19:01 UTC

How's that wife beating going?
OK Davis. Now lock the thread before too many more people start thinking about conflict of interest and liability issues.

174 posts, currently back on Page 3 (with the also-locked-for-no-hint-of-a-legitimate-reason "Zach Marzec" thread) with 3826 hits.
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Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Weak links

Post by Tad Eareckson »

Jim Rooney - 2007/07/22 22:30:28 UTC

I've heard it a million times before from comp pilots insisting on towing with even doubled up weaklinks (some want no weaklink).
Jim Rooney - 2009/11/03 06:16:56 UTC

God I love the ignore list

I have no time for such circular logic.
I had it with that crap years ago.
Jim Rooney - 2011/08/25 04:55:25 UTC

I've been through all these arguments a million times... this is my job.
Jim Rooney - 2011/08/25 05:23:34 UTC

Yeah, weather was kinda cool today... got some flying in actually.
Like I said... I've been through this a thousand times.
Jim Rooney - 2011/08/26 07:22:00 UTC

But when I say "this is what we do and it works", I'm sick to death of hearing BUT YOU'RE WRONG!!!!!!!!
Jim Rooney - 2011/08/26 07:51:12 UTC

So pardon me if I get a bit irritated at people telling me that I need to reconsider something from someone who's just now getting to something that we've been over a million freakin times already.
Jim Rooney - 2011/08/26 10:11:31 UTC

As I said.
Been through this shit a million freaking times.
Jim Rooney - 2011/08/26 17:34:33 UTC

Zach,
We're not in disagreement. In fact, you're reiterating all kinds of stuff that I try to get across to people all the time.

As I said, I've been through this a million freaking times.
Jim Rooney - 2011/08/28 10:15:12 UTC

I've heard it a million times and it's a load of shit.
Jim Rooney - 2011/08/29 13:40:42 UTC

I said I'm sick to death of inexperienced people arguing with experienced people. It boggles my mind.
Jim Rooney - 2011/08/31 09:25:57 UTC

Oh how many times I have to hear this stuff.
I've had these exact same arguments for years and years and years.
Nothing about them changes except the new faces spouting them.

Ok, I'm tired of this.
I'm not really sure who you're trying to convince.
Again, I don't care to argue this stuff.
I'll answer actual questions if you're keen to actually hear the answers, but arguing with me? Really? Have fun with that.

Gimme a call when you think of something that we haven't already been through years ago... cuz to date, you have yet to come up with anything new. Well, maybe it's new to you I guess. It's old as dirt to me though.
Jim Rooney - 2013/02/11 19:22:18 UTC

Sorry, I'm sick and tired of all these soap box bullshit assheads that feel the need to spout their shit at funerals. I just buried my friend and you're seizing the moment to preach your bullshit? GO FUCK YOURSELF!!!!!!!!

I can barely stand these pompus asswipes on a normal day.
Jim Rooney - 2013/02/12 18:00:27 UTC

I get tired as hell "refuting" all these mouth release and "strong link" arguments. Dig through the forums if you want that. I've been doing it for years but unfortunately the peddlers are religious in their beliefs so they find justification any way they can to "prove" their stuff.
Jim Rooney - 2013/02/16 05:05:41 UTC

I've had this conversation with many people.
Jim Rooney - 2013/02/17 00:34:14 UTC

We've been at this a long time and have gone over and over all these little arguments before that you think are "new".
They're new to you.
But they're old hat to "us".
Jim Rooney - 2013/02/17 10:37:47 UTC

When you come back to reality, let me know.
Till then, I'm sick of it.
Jim Rooney - 2013/02/19 02:22:35 UTC

I'm still confused about this question that I'm supposed to be answering.
Btw, if I'm a "newbie" as you're suggesting, why would it matter about any question I have to answer?
I mean, it's not like I've been doing this for a job since 2004 right?
Sorry I can't help.
Jim Rooney - 2013/02/27 09:45:26 UTC

I thought we'd already solved the world's problems... but apparently not.
Jim Rooney - 2013/02/28 01:17:55 UTC

I'm a bit sick of all the armchair experts telling me how my friend died.
Jim Rooney - 2013/03/03 19:37:19 UTC

My response is short because I've been saying it for years... and yes, I'm a bit sick of it.
This is a very old horse and has been beaten to death time and time again... by a very vocal minority.

(Holy god, the names I've been called.)

I have little time for these people.
Jim Rooney - 2013/03/04 19:31:36 UTC

So, if you're interested in discussing something, let me know.
If you're just here to argue, dude, I've got so much better shit to waste my time with.
Jim Rooney - 2013/03/07 18:24:58 UTC

Go back to Tad's hole in the ground.
While you're there, ask him why he was banned from every east coast flying site.
Jim Rooney - 2013/03/05 19:42:58 UTC

My god my head hurts.

I'm tired of arguing with crazy.
As I said many times... there are those that listen with the intent of responding... you unfortunately are one.
Jim Rooney - 2013/03/07 18:24:58 UTC

Go back to Tad's hole in the ground.
While you're there, ask him why he was banned from every east coast flying site.
Jim Rooney - 2013/03/10 08:12:02 UTC

Ok, more insanity. Fun.

I'm just bored and I find stirring up your little hornet's nest amusing for some reason.
Hey Jimmy...
Jim Rooney - 2011/08/26 10:11:31 UTC

Please quit trying to educate me about my job.
Part of your job is to train aerotow pilots so that they're safe and competent and thoroughly understand the principles fundamental to what they're doing, right?

So how come you - and the rest of your cult of 130 pound Greenspotters - with all of your experience and the practice you get, so obviously and thorouhly suck at it?

Compare/Contrast with my small but consistent 1.5 G crowd. Who's making more sense and which way is the pendulum swinging?
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Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Weak links

Post by Tad Eareckson »

http://www.hanggliding.org/viewtopic.php?t=11497
Aerotow release options?
Tad Eareckson - 2009/07/04 11:50:50 UTC

Two things I'm sure of - death and taxes.

And one of the factors that goes into the first thing...

When you lose tow tension your angle of attack goes way up.

And if your angle of attack was way too high to begin with, your hang glider may not ever again be of any use to you or anyone else.
Jack Axaopoulos - 2009/07/04 12:13:01 UTC

Bullshit.

a) only the pilot can let the angle of attack increase when you lose tension. Thats 100% on the pilot. You are simply wrong and misleading again.

b) "And if your angle of attack was way too high to begin with..." Which should never be the case or youre making a pilot error. Again, you are misleading people.

This is the problem I have with you. You attempt to fallaciously attribute pilot errors to issues of mechanical towing devices or other things.

Sorry... but if you suddenly lose power, your nose just doesnt pop :roll:
Michael Bradford - 2009/07/04 13:48:47 UTC
Rock Spring, Georgia

SG,

A glider under tow is a powered aircraft. String powered. When climbing under power, the angle of attack is relevant to the climb path, not the horizon. And if the tow force is subtracted instantly, the angle of attack is instantly translated, whether or not there is pilot input. A classic Departure Stall can easily, almost instantly result. Pitch and power are not independent forces.

If you are in the middle of a climbing correction when the "power" fails, failure to immediately lower the angle of attack can yield an immediate deep stall.

A correct statement might be that "Only the pilot can compensate for the naturally increased angle of attack when you abruptly lose tension."

A glider under tow is a powered aircraft.
So Mike...

You're saying that, regardless of what's going on with the air, as long as the pilot of a pitched up aircraft reacts properly/instantly to a catastrophic power failure or loss of tension it's physically impossible for a stall to result - even if the pilot isn't some idiot pro toad?

P.S. Don't believe I heard your voice in any of the Zack Marzec postmortem discussions. So how come? The guy was an instructor in a state rubbing part of the north edge of yours and killed in one marking your southern boundary and there was a lot of heated talk about the incident that ended - or was ended - without resolution.

And lemme tell ya sumpin'...

Somebody on The Jack Show really needs to call the cowardly goddam piece of shit with the lock, delete, and ban buttons out on the crap that he's been saying, doing, and getting away with and tell him to go fuck himself.
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Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Weak links

Post by Tad Eareckson »

http://ozreport.com/forum/viewtopic.php?t=24846
Is this a joke ?
Jim Rooney - 2011/08/31 09:25:57 UTC

Oh, I thought of an other one... I smashed into the earth after my weaklink let go cuz I fly as badly as I tow, and I'm only still here cuz my weaklink didn't let me pile in harder.
http://4.bp.blogspot.com/-bRrpHNa68iY/UQ6Pv9gRZyI/AAAAAAAAjTg/Hc22bx5122Q/s2048/20943781_BG1.jpg
Image
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Tad Eareckson
Posts: 9161
Joined: 2010/11/25 03:48:55 UTC

Re: Weak links

Post by Tad Eareckson »

http://ozreport.com/forum/viewtopic.php?t=31563
The Jeff's together again
Davis Straub - 2013/03/23 01:34:45 UTC

Up in the air but not far apart (Torrey Pines)

http://vimeo.com/61198259


Thanks Daniel
Angelo Mantas - 2013/03/26 01:21:05 UTC

I thought this was pretty cool - until the 3:20 mark. I really don't think promoting midairs is a good idea. Take a look at this still - after the collision, one of the gliders is pointing straight down and the pilot is fully pushed out. The video immediately switches to another scene - maybe they didn't want to show his tumble and recovery?

http://ozreport.com/forum/files/midair_173.jpg
Image
http://live.staticflickr.com/65535/51852296471_d1a2b640b5_o.jpg
Davis Straub - 2013/03/26 02:18:26

No tumble. They went on flying just fine. I've linked to the original previously. That's why the title.
Angelo Mantas - 2013/03/26 04:23:42 UTC

I see. No biggie, just another midair. And we wonder why people think we're nuts.
But...
Paul Tjaden - 2008/07/22 04:32:22 UTC

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.
Davis Straub - 2013/03/10 14:09:22 UTC

I've had no problem releasing my barrel release hundreds of times.
Bart Weghorst - 2011/02/25 19:06:26 UTC

I've had it once where the pin had bent inside the barrel from excessive tow force. My weaklink was still intact. The tug pilot's weaklink broke so I had the rope. I had to use two hands to get the pin out of the barrel.
No stress because I was high.
Davis Straub - 2013/03/10 12:04:42 UTC

I like and will keep my barrel release. You can keep yours.
Lauren Tjaden - 2008/03/23 22:20:15 UTC

The barrel release wouldn't work because we had too much pressure on it.
Davis Straub - 2013/03/10 18:03:59 UTC

Jim has towed me before and has no problem towing me with this release.
Dennis Pagen - 2005/01

The first accident occurred in Germany at an aerotowing competition. The pilot launched with his Litespeed and climbed to about forty feet when he encountered a thermal that lifted him well above the tug. After a few moments, the glider was seen to move to the side and rapidly turn nose down to fly into the ground, still on tow, in a classic lockout maneuver. The impact was fatal.

Analysis

This pilot was a good up-and-coming competition pilot. He had been in my cross-country course three years ago, and this was his second year of competition. What happened to him is not too unusual or mysterious. He encountered so much lift that although he was pulling in the base bar as far as he could, he did not have enough pitch-down control to get the nose down and return to proper position behind the tug. This situation is known as an over-the-top lockout.

I am personally familiar with such a problem, because it happened to me at a meet in Texas. Soon after lift-off the trike tug and I were hit by the mother of all thermals. Since I was much lighter, I rocketed up well above the tug, while the very experienced tug pilot, Neal Harris, said he was also lifted more than he had ever been in his heavy trike. I pulled in all the way, but could see that I wasn't going to come down unless something changed. I hung on and resisted the tendency to roll to the side with as strong a roll input as I could, given that the bar was at my knees.
Davis Straub - 2013/02/12 20:01:14 UTC

There is very little danger of pulling in too far on the pro tow release. And on the 3 point releases the problem is not that the pilot pulls in too far, but rather that the glider is pulled down as the carabineer rises up the V-bridle.
Mark Frutiger - 2013/02/08 19:12:21 UTC

Zack hit the lift a few seconds after I did. He was high and to the right of the tug and was out of my mirror when the weak ling broke. The load on the tug was not excessive as with a lockout, but I was not surprised when the weak link broke.

I was still in the thermal when I caught sight of Zack again. I did not see the entry to the tumble, but I did see two revolutions of a forward tumble before kicking the tug around to land.
Davis Straub - 2013/03/06 18:29:05 UTC

You know, after all this discussion I'm now convinced that it is a very good idea to treat the weaklink as a release, that that is exactly what we do when we have a weaklink on one side of a pro tow bridle. That that is exactly what has happened to me in a number of situations and that the whole business about a weaklink only for the glider not breaking isn't really the case nor a good idea for hang gliding.

I'm happy to have a relatively weak weaklink, and have never had a serious problem with the Greenspot 130, just an inconvenience now and then.
http://4.bp.blogspot.com/-bRrpHNa68iY/UQ6Pv9gRZyI/AAAAAAAAjTg/Hc22bx5122Q/s2048/20943781_BG1.jpg
Image

Being pro toad with bent pin barrel releases and Davis Links is still totally cool - right Angelo?
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