It's a wrap
Davis Straub - 2011/07/29 15:16:29 UTC
Long weaklinks and wrapping up the line on your carabineer (Quest Air, Groveland, Florida)
Lauren Tjaden (tjadenhors) - 2011/07/29
Quest Air
I was flying a tandem this morning, and when I released (from the three point bridle) the line briefly released and then wrapped around the 'biner that we tow from. The sharp, strong pull almost immediately broke the weak link on the tug plane, which of course left me with the rope. I released the bridle from my shoulders (with the barrel release) and dropped the rope over the field without incident.
When I retrieved the rope and bridle after the flight, I was shocked at how profoundly the line had wrapped around the 'biner. I have heard about the line being able to wrap, but in thousands of aerotows I have never experienced it. I thought readers might be interested to see actually happens.
Secondly, although the weak link wasn't tremendously large, in retrospect it could have been smaller. Apparently the longer the weak link the greater its propensity to wrap. I also included a photo showing the size of the weak link. (I removed it from the 'biner after taking the photos.) Just a reminder for folks to keep their weak links on the stingy side.
Deltaman - 2011/07/29 22:06:51 UTC
Thanks Lauren for your report and pictures!
The measure of the outer part of weak link is inches or cm?
2.5 inches = 6.35 cm still too much!
Please tell me what was your shoulders installation? You hadn't weaklink there?
At the bottom end of the V-bridle I have got a weak link (bridle link) 1.2 times stronger than the one on the primary release. So when there is a wrap after top release, it blows immediately. And if it don't I will release with very little effort by a straight pin barrel release (4.5kg for a 90kg direct load (180kg with a bridle)). (Thanks Tad).
I don't want the line with me (a French pilot burned a field after catching a powerline). Easy to manage with good weak link values. 1 on the primary < 2 on the pilot side < 3 on the tug side. What was the value on the tug side?
What was your barrel. I tested my old one (curved pin): at 100 kg the curved pin bends and break! So in your case without weak link on pilot side, you had half of the towline tension on this barrel. The maximum tension you can have on this release is half of the tug weak link. A curved pin barrel is three times harder to release than with a straight one (Tad release). Take care.
Viktor Moroz - 2011/07/29 22:31:31 UTC
I'd like to advise you:
1. Change the carabiner with a metal ring of suitable size (welded and polished). Like an option.
2. Remove weaklink from the bridle and tie it between a tow line and a metal ring ('biner).
Have a safe flights,
Viktor
Steve Davy - 2011/07/30 03:15:36 UTC
"Weak links are made as short as possible - within the confines of release operation demands - in order that they be incapable of contributing to a wrap."
I offer $25 to the first person that can tell me who wrote that.
Deltaman - 2011/07/30 06:19:30 UTC
Too easy ! His name is on my first post. Send me 25 !
And this one ?Always use an appropriate weak link with a finished length of 1.5 inches or less. Longer weak links are more likely to get tangled on the tow ring upon release.
Davis Straub - 2011/07/30 15:03:35 UTC
There is a reason for using these carabineers. I think that you can figure it out.
Paul Tjaden - 2011/07/30 15:33:54 UTC
Quest Air has been involved in perfecting aerotowing for nearly twenty years and I can say that the steel ring, polished or not, has a greater tendency to wrap than the small aluminum carabiners. There are other obvious reasons a heavy steel ring is not a great idea swinging around at the end of a 250 foot line.
On the chest line we normally run a double weak link on one end just as we do with the primary. This is probably not the optimum situation and can and does lead to the weak link on the Dragonfly tow bridle breaking before that one will break. Having the rope is not a big problem if you have altitude but can be an issue down low. Although it is easy to get rid of with the chest barrel release, perhaps we will reduce the strength of the chest weak link to one loop. It's always a balancing act. It's no fun having an inadvertent low weak link break when you are low so we don't want this weak link too weak.
Paul Tjaden - 2011/07/30 15:37:48 UTC
Just re-read Viktor's post. Placing the weak link between the tow rope and the carabiner has merit but it will wear out very quickly. Seems it might need to be changed every flight?
Sam Kellner - 2011/07/30 17:06:39 UTC
These are great photos, but as usual, it is difficult to see all the details from the pictures. If my observations are incorrect, I will gladly stand corrected.
By looking at these shots, it appears the way the weak link was tied, not a grapevine, might be a contributing factor.
The weak link wrapped up around the biner, then the loop hooked the large wl knot, much like a key hole type fastener, like on many haul-backs and nose wires.
What happened to the grapevine knot?
You guys keep up the good work at QuestAir.
Sam,
Southwest Texas Hang Gliders
Viktor Moroz - 2011/07/30 19:22:42 UTCYes, of course. But seems to me it's not an issue when we are talking about safety. Weaklink rope is a cheap thing.Placing the weak link between the tow rope and the carabiner has merit but it will wear out very quickly. Seems it might need to be changed every flight?
Usually we perform three aerotows before changing weaklink. Sometimes - four, sometimes only one. It depends of state of a weaklink. Visual inspection and so on. I'm talking about solo flights.
During competitions we change weak link every time.
Of course, I'm agree with you about "balancing act".
Davis Straub - 2011/07/30 19:51:54 UTC
I'm very happy with the way Quest Air (Bobby Bailey designed) does it now.
Steve Davy - 2011/07/30 21:06:04 UTC
Wills Wing. We are even.
http://www.willswing.com/Articles/Article.asp?reqArticleName=AerotowRelease
Kinsley Sykes - 2011/07/30 21:09:42 UTCMe too. My secondary weaklink would have blown in milliseconds if the carabeiner wrapped like that, only reason that one did not in this case was the stronger weaklink for the tandem tow.I'm very happy with the way Quest Air (Bobby Bailey designed) does it now.
Good to know that a long one like that can wrap. Thanks Lauren for the photo and notification and glad it worked out OK for you.
Marc Fink - 2011/07/31 13:38:20 UTC
Sam,
Agreed--good eyes, the knot does look like in a strange position--like it's providing a "hitching post" for wraps.
Steve Davy - 2011/07/30 21:06:04 UTC
Could someone please tell me the function of the "weak link"? Thanks.
---Davis Straub - 2011/07/31 17:55:25 UTC
To break under load before the glider does.
- It's a two point - pilot and glider.Lauren Tjaden - 2011/07/29 15:16:29 UTC
I was flying a tandem this morning, and when I released (from the three point bridle)...
- You don't release from it. You keep it with you.
Why?The sharp, strong pull almost immediately broke the weak link on the tug plane...
'Cause it just says "SHOULD"?The United States Hang Gliding and Paragliding Association, Inc.
Standard Operating Procedure
12. Rating System
02. Pilot Proficiency System
10. Hang Gliding Aerotow Ratings
-B. Aero Vehicle Requirements
05. 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 100 pounds greater than the glider end.
But it's not like you are any of the douchebags who "trained" and fly with you have ever actually read - let alone made any half-assed effort to comply with - the SOPs. Right?
http://www.chgpa.org/forums/viewtopic.php?f=2&t=3107I released the bridle from my shoulders (with the barrel release)...
I have a tandem rating!!!
Yeah, those things work just great - as long as there's no PRESSURE on them, don't they?Lauren Tjaden - 2008/03/23 22:20:15 UTC
The barrel release wouldn't work because we had too much pressure on it.
You mean without any incident in addition to the two potentially lethal ones you just had, right?...and dropped the rope over the field without incident.
Yeah. Me too. Shocked. SHOCKED!When I retrieved the rope and bridle after the flight, I was shocked at how profoundly the line had wrapped around the 'biner.
Well then, it was OBVIOUSLY appropriate for you to do absolutely nothing to eliminate the possibility of it happening and continue aping your Ridgely and Quest douchebag friends.I have heard about the line being able to wrap, but in thousands of aerotows I have never experienced it.
Anybody got any photos of Chris McKee in case the readers might be interested to see what actually happens when it never occurs to them that it's a good idea to stow their pod zipper lanyards before they get on launch dollies?I thought readers might be interested to see actually happens.
Yeah, just triple the protrusion appropriate for engaging a spinnaker shackle.Secondly, although the weak link wasn't tremendously large...
Great. You've been living, breathing, dreaming aerotow for over nine years and this is "in retrospect"....in retrospect...
Do ya think?...it could have been smaller.
DUDE!!! I'm thinkin' Oslo!Apparently the longer the weak link the greater its propensity to wrap.
Yeah, everybody listen to Lauren - 'cause she's a tandem instructor and helps run a tow park.Just a reminder for folks to keep their weak links on the stingy side.
Yeah!!!Deltaman - 2011/07/29 22:06:51 UTC
Thanks Lauren for your report and pictures!
http://www.chgpa.org/forums/viewtopic.php?f=2&t=3107Please tell me what was your shoulders installation?
I have a tandem rating!!!
What do you think?Lauren Tjaden - 2008/03/23 22:20:15 UTC
The barrel release wouldn't work because we had too much pressure on it.
Obviously not one that mattered.You hadn't weaklink there?
Sorry Antoine, you lost her at:At the bottom end of the V-bridle I have got a weak link (bridle link) 1.2 times stronger than the one on the primary release.
Never in her life has Lauren dealt with a number other than 2, 3, or 4 in a discussion of weak links - and these only with respect to numbers of strands of 130 pound Greenspot. She has no more clue as to concepts of pounds or Gs than any of the other Made Men and Women in the Flight Park Mafia.2.5 inches = 6.35 cm
Three strands - on the bridle.What was the value on the tug side?
So? It's standard equipment. Everybody uses it. That's all that's important. (And what's a "kg" anyway?)I tested my old one (curved pin): at 100 kg the curved pin bends and break!
Fuck Tad. When was the last time he even thought about hooking into a glider?A curved pin barrel is three times harder to release than with a straight one (Tad release).
For something new and different.Take care.
I want royalties. Five percent.Steve Davy - 2011/07/30 03:15:36 UTC
I offer $25 to the first person that can tell me who wrote that.
- Yeah. It's to save five seconds every time a glider hooks up.Davis Straub - 2011/07/30 15:03:35 UTC
There is a reason for using these carabineers. I think that you can figure it out.
http://ozreport.com/13.238
Adam Parer on his tuck and tumble
Which is real important when you're using 130 pound Greenspot in actual thermals 'cause you're having to launch all the gliders twice.Adam Parer - 2009/11/25
Due to the rough conditions weak links were breaking just about every other tow and the two tugs worked hard to eventually get everyone off the ground successfully.
- At least he figured out how to spell them.
Yeah, the same way the Jehovah's Witnesses have been involved in perfecting teaching in the biology classroom. So after nearly twenty years of aerotowing Quest has discovered that a weak link three times longer than it should be can tie itself to a tow ring. What surprise do you have in store for the few of us that are still gonna be around in 2030? Bent pin releases don't work under load?Paul Tjaden - 2011/07/30 15:33:54 UTC
Quest Air has been involved in perfecting aerotowing for nearly twenty years...
That's GREAT!...I can say that the steel ring, polished or not, has a greater tendency to wrap than the small aluminum carabiners.
- Any chance we can get a peek at the data you're using to justify that statement?
- So how come you're using a welded steel ring on the FRONT end of the towline to engage the Dragonfly bridle? Shouldn't you be using a small aluminum carabiner there too? What percentage of the time do you get a wrap when you blow the front end?
- So how does that compare to the issue of the two and half inch protrusion weak link?
http://www.hanggliding.org/viewtopic.php?t=14230
pro tow set-up
- How 'bout that four foot long one point bridle you're using in your avatar photo?Jim Rooney - 2009/11/02 18:58:13 UTC
Oh yeah... an other fun fact for ya... ya know when it's far more likely to happen? During a lockout. When we're doing lockout training, the odds go from 1 in 1,000 to over 50/50.
Why is it that length? 'Cause that's what everybody else uses and always has?
- I didn't hear him say anything about a HEAVY steel ring.There are other obvious reasons a heavy steel ring...
- There are rather blindingly obvious and way more critical reasons not to use bent pin barrel releases. But they haven't made a single freaking dent in your thinking, have they?
POUNDS? Just kidding, you don't have any more of a clue than anybody at Quest or the assholes who trained you at Ridgely ever had.On the chest line we normally run a double weak link on one end just as we do with the primary.
So what's stopping you from beefing up the one at the front and making some pretense of running a safe operation? Oh, right. Nobody does it that way.This is probably not the optimum situation and can and does lead to the weak link on the Dragonfly tow bridle breaking before that one will break.
Yeah Paul, NOTHING'S a big problem if you have altitude.Having the rope is not a big problem if you have altitude...
Yeah. Talk to Shane Smith about that....but can be an issue down low.
Yeah. Just as long as everything else is going great and you have plenty of time and don't hafta fly the glider.Although it is easy to get rid of with the chest barrel release...
- Without, of course, having a freaking clue as to the breaking strengths of either the single or double loops....perhaps we will reduce the strength of the chest weak link to one loop.
- And of course we can't even consider upping the front end 'cause if it were a good idea people would already be doing it that way.
Unless you wanna go to the trouble of figuring out what the fuck you're doing and get it right - the way sailplanes do it in REAL aviation.It's always a balancing act.
As opposed to having an:It's no fun having an inadvertent low weak link break when you are low...
- inadvertent:
-- low weak link break when you are high
-- high weak link break when you are:
--- low
--- high
- advertent:
-- low weak link break when you are:
--- low
--- high
-- high weak link break when you are:
--- low
--- high
http://ozreport.com/forum/viewtopic.php?t=11591...so we don't want this weak link too weak.
Where to put the weaklink - the HGFA rules
And, of course, without any consideration whatsoever of what can happen if the bottom end of the primary bridle wraps.Rohan Holtkamp - 2008/04/21
Once again history has shown us that this thread-through system can hook up and the hang glider remains being towed by the keel only, with the bridle well out of reach of even a hook knife. I know of just one pilot to survive this type of hook-up, took him some twelve months to walk again though.
http://www.hanggliding.org/viewtopic.php?t=11497Paul Tjaden - 2011/07/30 15:37:48 UTC
Just re-read Viktor's post. Placing the weak link between the tow rope and the carabiner has merit but it will wear out very quickly. Seems it might need to be changed every flight?
Aerotow release options?
Oh. And did you have any thoughts on those piece o' shit bent pin Bailey "releases" Antoine was trying to warn you about? Or did you just automatically go into major head-in-sand mode the instant you saw the name "Tad"?Adi Branch - 2009/07/02 12:50:02 UTC
I have to chirp in on this.. I know I'm a noob and all that, but Tad seems to be talking sense to me. From what I can gather the US has some quite different (dated?) ways of doing things which it appears are not used here in the UK, and some of the reasons I've heard cited for not using these methods relate directly to accidents in the US.
For instance, the idea of tying your own weak link is absolute nuts to me, as is using a bit of string for the job! Over here it's aluminium only (sailplane style link) and if I turned up with a bit of tied string, I'd be shown the exit road.
FER SURE!!! The people on the International Darwin Awards Committee eat this stuff up. And it's not like people wanna look at photos of how NOT to do things unbelievably stupidly.These are great photos...
http://www.flickr.com/photos/aerotowrelease/8305428629/
http://www.flickr.com/photos/aerotowrelease/sets/72057594141352219/detail
What part of:By looking at these shots, it appears the way the weak link was tied, not a grapevine, might be a contributing factor.
are you having the MOST trouble understanding?Weak links are made as short as possible - within the confines of release operation demands - in order that they be incapable of contributing to a wrap.
Funny, MY concept of "good work" is that you only screw ONE pooch in the course of an ordinary tow seriously enough to get you and your passenger killed in less benign circumstances. Must be a Southwest Texas thing.You guys keep up the good work at QuestAir.
http://www.tost.de/Viktor Moroz - 2011/07/30 19:22:42 UTC
During competitions we change weak link every time.
Of course you are Davis. Whenever someone leaves launch in a chopper or body bag the field of competition gets a little narrower for you.Davis Straub - 2011/07/30 19:51:54 UTC
I'm very happy with the way Quest Air (Bobby Bailey designed) does it now.
Where they tell you:Steve Davy - 2011/07/30 21:06:04 UTC
http://www.willswing.com/Articles/Article.asp?reqArticleName=AerotowRelease
- to use "an appropriate weak link" without giving you the slightest hint what an appropriate weak link is;
- where to slap on some piece o' shit Quest or Lookout release 'cause they won't just build them into their goddam gliders like sane people would do.
- and to "Carry a hook knife when towing." so you can pretend that'll actually do you some good when the commercial junk - that Wills Wing knows from just looking at it will fail - fails.
Yeah Kinsley, who isn't? Certainly not anyone who ever again wants a chance of flying at a US operation.Kinsley Sykes - 2011/07/30 21:09:42 UTCMe too.I'm very happy with the way Quest Air (Bobby Bailey designed) does it now.
My secondary weaklink would have blown in milliseconds if the carabeiner wrapped like that...
You're welcome.Hang Gliding - 1997/02
Tad Eareckson
To further address the danger of a primary release failure (bridle wrap), a secondary weak link, of strength somewhere between significantly stronger than and double that of the primary, should be installed at the other end of the primary bridle.
Yeah. Now let's get some good photos of cars folded in half around telephone poles with dead teenagers in them so we know what can happen when people get drunk and try to take forty mile per hour curves at eighty on rainy nights.Good to know that a long one like that can wrap. Thanks Lauren for the photo and notification and glad it worked out OK for you.
Any chance you wanna see how to do things RIGHT instead?
http://www.flickr.com/photos/aerotowrelease/8306258400/
http://www.flickr.com/photos/aerotowrelease/sets/72057594141352219/detail
Just kidding, don't bother.
What part of:Marc Fink - 2011/07/31 13:38:20 UTC
Agreed--good eyes, the knot does look like in a strange position--like it's providing a "hitching post" for wraps.
do you not understand? (Rhetorical question. You never made it past the second word.)Weak links are made as short as possible - within the confines of release operation demands - in order that they be incapable of contributing to a wrap.
Thank YOU! You just set that stupid sonuvabitch up for me REALLY WELL.Steve Davy - 2011/07/31 16:49:09 UTC
Could someone please tell me the function of the "weak link"? Thanks.
http://ozreport.com/12.081Davis Straub - 2011/07/31 17:55:25 UTC
To break under load before the glider does.
Weaklinks - the HGFA rules
So what you're saying (dickhead) is that anything on any solo glider heftier than "a single loop of Cortland 130 lb Greenspot braided Dacron Tolling line" on ONE end of a shoulder bridle (ferchrisake don't use them on BOTH ends of the bridle - that means you won't blow tow until you hit twice the tension - or you'll blow off at half (I can never remember which)) will hold until a cross spar buckles.Davis Straub - 2008/04/22 14:47:00 UTC
From section 3.4 of the 1999 Hang Gliding Federation of Australia Towing Manual:Here is the requirement from the 2007 Worlds local rules (which I wrote) for weaklinks:Recommended breaking load of a weak link is 1g. - i.e. the combined weight of pilot, harness and glider (dependent on pilot weight - usually approximately 90 to 100 kg for solo operations; or approximately 175 kg for tandem operations).At the 2008 Forbes Flatlands Greenspot for the first time was used as the standard weaklink material (thanks in large part to the efforts of Bobby Bailey). We applaud these efforts to improve the safety of aerotowing by using a better weaklink material.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.
Thank you SO much for clarifying that.
And many thanks to you to Bobby - for all you've done improve the safety of aerotowing by using a better weaklink material.
(Better than what I've never heard but whatever it was we sure must've been breaking up a lot of gliders with it.)
And MANY extra thanks for putting that breakaway tow mast on the Dragonfly to help keep us glider drivers even safer - whether we want to be or not.