I watched a friend break his arm Saturday and take out the downtubes of his Falcon 3 170 and wanted to get some ideas from you guys on how you deal with situations that you know are going to end badly, but the pilot doesn't want to listen. My buddy went out to Arizona last month to get his surface tow rating from Mark Knight. When he returned, he asked Mel Glantz (the local advanced instructor) to tow him up with his big winch. I was just driving by and stopped to watch and say hi.
I was asking my buddy how Mark taught and my buddy Bryan seemed stressed and looked like he was rushing to get ready and get on line as Mel had towed once and the winch was humming along.
He was connecting his paraglider tow bridle to his harness (Z5) shoulder loops and I thought that was weird, and asked him about it. He told me "that's how I towed all week" so I asked him if he was going to tow with it over or under his basetube and he replied "I did both and it doesn't make any difference". This scared me, so I asked him how much theory Mark taught, and my buddy said "None. We just flew a lot." I laughed and said "That's cool, but they had you take a written test, didn't they?" and he got mad (he was already stressing) and said "Larry, we just flew and those guys said I was flying like a Hang 3.", at which point I just walked away and waited for something bad to happen......which it did 5 minutes later.
He rushed to the end of the line while Mel was still in the air, rushed to hook in, did a hang check, and hook up and was calling go.go.go while I was still trying to figure out how to do video on my phone. I looked up and he's almost fully prone with his hands still mid-tube on downtubes, his nose pitched way up and about 10 feet off the ground. At that moment, the weaklink broke. (He was using that lame greenstripe crap and no one had talked to him about weak links as far as I know. He had a 1000 foot roll of the stuff in the back of his van. He was just using "what they told him to use".) So the nose pitched forward to dive into the ground and his arms were still fully extended and locked so he went through both of them taking his right arm out as he went.
Now that I read that, I think that maybe my questions increased his mental tension and distracted him or put him in a mood of "damnit, I'm gonna go". God, I hope it wasn't me quizzing him that made him go that way.
You can all see the physics of why his arm is in four pieces now and why all his new gear is for sale, but what success have you all had talking and convincing a friend(s) to slow down and relax and think about things before they do damage that you can see coming? Is there a time tested way of getting a pilot to back away instead of rushing forward?
Mel's attitude was "the guy just got his ST rating last month and Mark told me he was flying great" (Mel had called Mark and asked how he did), but I wouldn't have towed him without talking a lot more to him and doing some low energy moon walks and practice releases in a Condor or some other big friendly glider, and would have asked my winch man not to tow him with the "don't bother me, I got my rating" attitude he was exhibiting. It wasn't my winch or winch-man though and I was just watching and Mel is the advanced instructor and examiner here, so I don't have a lot of clout.
I think the operator of the winch should have shut down the winch and come over and talked to the pilot more before launching him or at least told the pilot "let's wait for Mel", and I sort of wish I had tried to get them all to slow down and just talk about the process, but I'm already seen as the "analytical nerd that talks too much" here and don't get a lot of the "just do it" guys to listen to me (sound familiar, Tad?). I plan to have lunch with Mel soon and try to talk him into a little more process and a little less "go for it".
Do you all have any "things to say that work"?
Broken arm Saturday for discussion
-
Tad Eareckson
- Posts: 9161
- Joined: 2010/11/25 03:48:55 UTC
Re: Broken arm Saturday for discussion
Manna from heaven.Broken arm Saturday for discussion
Hell, why ask me? I've been screaming this stuff at the top of my lungs for decades and you know what kind of success rate I've had.I watched a friend break his arm Saturday and take out the downtubes of his Falcon 3 170 and wanted to get some ideas from you guys on how you deal with situations that you know are going to end badly, but the pilot doesn't want to listen.
I'm not real happy with Mark Knight.My buddy went out to Arizona last month to get his surface tow rating from Mark Knight.
- Four years ago he was asking about weak links, I thoroughly explained the issue to him and warned him about how dangerous 130 pound Greenspot was.
- He was part of that Mingus Do-A-Hang-Check-At-The-Back-Of-The-Ramp-And-Assume-You're-Hooked-In crowd that got Kunio killed later that season and - in fact - was the first person to reach his lifeless body and start doing the useless CPR routine. And nothing's changed for the better in that neck of the woods since.
(I've considered trying to engage those assholes but they didn't participate in any of the extensive Davis Show postmortem discussion and I know from long experience EXACTLY the reaction I'd get.)
- He's associated with that idiot crowd that got Shane Smith killed thirteen months ago in what is probably the stupidest towing fatality I've ever heard about and I got this crap:
http://groups.yahoo.com/group/TUGS/message/1148
Tug Rates
...from him after using the "facts" he himself had posted. (And I note that no varying or further facts were ever forthcoming.)Mark Knight - 2011/02/10 19:57:25 UTC
Learn the facts.
You have no idea what happened.
- He was one of the idiots - along with Mitch Shipley and the other Quest assholes - who gave NMERider the tow training he needed to belly himself in downwind on 130 pound Greenspot last summer.
So - not that it's directly relevant here - what was it? I'm guessing a three-string with the lanyard also anchored at a shoulder loop?He was connecting his paraglider tow bridle to his harness (Z5) shoulder loops...
Good instincts.This scared me...
Stupid question....so I asked him how much theory Mark taught...
He had already answered it at that point."I did both and it doesn't make any difference."
And John Woiwode was flying like a Hang Five - but when you're towing and totally clueless on theory you can get instantly and permanently converted to a Hang Zero."Larry, we just flew and those guys said I was flying like a Hang 3."
And from that point on...He rushed to the end of the line while Mel was still in the air, rushed to hook in, did a hang check...
http://www.hanggliding.org/viewtopic.php?t=4046
Accident Report
...assumed he was connected to his glider.Doug Koch - 2007/10/20 15:42:57 UTC
Las Vegas
He started to come in to land and at about 20-30 feet suddenly dropped from the glider. As he was in a semi-prone attitude he came down at an angle of a few degrees and impacted the ground on both feet and then fell forward on his face.
The impact broke both legs at the ankles and drove his shin bones out the bottom of his feet six inches.
Next time someone says:...while I was still trying to figure out how to do video on my phone.
start trying to figure out how to do video on your phone IMMEDIATELY."I did both and it doesn't make any difference."
Meaning he foot launched. Do they not have or provide a dolly?I looked up and he's almost fully prone with his hands still mid-tube on downtubes...
(Guess he needed the extra roll authority. Right, miguel?)
Guess he went with the bridle under the basetube. (Not that that matters.)...his nose pitched way up...
http://ozreport.com/forum/viewtopic.php?t=24846At that moment, the weak link broke...
Is this a joke ?
Guess 130 pound Greenspot is gender neutral. That's a good thing - I so hate discrimination of any kind in this sport.Jim Rooney - 2011/09/02 19:41:27 UTC
Yes, go read that incident report.
Please note that the weaklink *saved* her ass. She still piled into the earth despite the weaklink helping her... for the same reason it had to help... lack of towing ability.
...he was using that lame greenstripe crap and no one had talked to him about weak links as far as I know.
Somebody was SUPPOSED to have talked to him about it.The United States Hang Gliding and Paragliding Association, Inc.
Standard Operating Procedure
12. Rating System
02. Pilot Proficiency System
11. Hang Gliding Special Skill Endorsements
04. Surface Tow (ST)
-a. Must demonstrate tow system set up and preflight, including a complete discussion of all of the factors which are particular to the specific tow system used, and those factors which are relevant to towing in general. Must demonstrate complete understanding of both normal and emergency procedures, including checklists for normal procedures and the indications of an impending emergency, and convince the instructor of his/her ability to recognize and execute emergency procedures.
-b. Demonstrates successful, confident, controlled launches and flight under tow to release altitude, with a smooth transition to flying, with proper directional and pitch control resulting in the proper tracking of the tow line and appropriate maintenance of proper tow line tension and airspeed. Such demonstrations may be made in ideal wind conditions.
-c. Has discussed all Towing Discussion Topics with the issuing ST official.
Think he wants to sell what he has left? I could use it for its intended purpose - and the bass tend not to get very big around here so it would probably be up to the job.He had a 1000 foot roll of the stuff in the back of his van.
- Who's "THEY"? Mark?He was just using "what they told him to use"...
- Where was he using it? If he's:
-- using a paraglider bridle/release assembly I'm thinking it's gotta be between the release and the towline.
-- engaging a loop of 130 pound Greenspot with a three-string (instead of configuring it between the towline and a tow ring) he's asking to get killed in a manner similar to the one that took out Shane.
-- using it between the bridle/release assembly and the towline it's seeing the full tow tension (versus the half it would see on the end of a one point aerotow bridle). If that were the case I'm amazed he made it all the way up to ten feet.
-- configuring the same way but using a double loop he's still dangerously understrength.
...so the nose pitched forward to dive into the ground...
See, Zack? They always come down head first - even (especially) if they have their hands on the downtubes - and it's always gonna be bad when they get to the surface. Go ahead and zip the pod up on the cart.Tad Eareckson - 2012/02/13 15:27:45 UTC
- A tow situation is only bad if it's near the ground. Anything else is just an inconvenience.
- Bad:
-- dolly and platform launch situations involving halfway competent pilots are so rare as to be virtually nonexistent
-- tow situations WAY more often than not require that the glider remain on tow
- In a bad tow situation:
-- in which release is appropriate it can almost never be effected by anyone at either end in time to prevent a catastrophic crash.
-- - foot, dolly, platform - the pilot ALWAYS comes down head first and is usually killed. It makes absolutely no difference if his feet are in or out of a cocoon or pod.
- Here's a glider diver and 130 pound Greenspot induced mildly unpleasant tow situation:
http://www.youtube.com/watch?v=vb4nUTAJXTk
Aerotow Incident
Sparkozoid - 2009/12/01
dead
The safety margin of the recovery is NOT enhanced by the diver going upright and landing on his feet.
- Big surprise....so he went through both of them taking his right arm out as he went.
- Guess it's a no brainer that he is (was) right handed.
Thanks again, Donnell.Donnell Hewett - 1980/12
Now I've heard the argument that "Weak links always break at the worst possible time, when the glider is climbing hard in a near stall situation," and that "More people have been injured because of a weak link than saved by one."
No. He didn't crash because your questions increased his mental tension and distracted him or put him in a mood of "damnit, I'm gonna go".Now that I read that, I think that maybe my questions increased his mental tension and distracted him or put him in a mood of "damnit, I'm gonna go".
http://ozreport.com/forum/viewtopic.php?t=26134Manned Kiting
The Basic Handbook of Tow Launched Hang Gliding
Daniel F. Poynter
1974
"The greatest dangers are a rope break or a premature release." - Richard Johnson
Whipstall almost tumble
Mike Lake - 2011/12/28 12:11:54 UTC
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. 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.
He was gonna tow the way he was taught by his idiot instructor and use what they told him to use. And it was gonna blow at ten feet - at the worst possible time, when the glider was climbing hard in a near stall situation - and he was gonna come down headfirst and break two downtubes and an arm regardless of any mental tensions, distractions, and moods or lack thereof.Mike Lake - 2011/06/18 00:33:31 UTC
In the future pilots will look back at this era and wonder why we were all so blind when it comes to weaklink values, just as we now look back and wonder why we ever flew without tip sticks or other dive recovery devices.
Don't sweat anything. You were the only participant in that fiasco and the history leading up to it who behaved in a responsible manner.God, I hope it wasn't me quizzing him that made him go that way.
- He wasn't a pilot. And maybe now never can be - of the hang glider variety anyway.Is there a time tested way of getting a pilot to back away instead of rushing forward?
- Yeah, you TRAIN him as a pilot before you let him ACT as a pilot. That's how things work in REAL aviation.
That SHOULD HAVE BEEN enough. That's what a rating is for. Ya got one you're supposed to be able to surface tow competently and safely.Mel's attitude was "the guy just got his ST rating...
You shouldn't have had to. However...but I wouldn't have towed him without talking a lot more to him and doing some low energy moon walks and practice releases in a Condor or some other big friendly glider...
...knowing Mark and USHGA......and would have asked my winch man not to tow him with the "don't bother me, I got my rating" attitude he was exhibiting.
Idiots are most comfortable / socially compatible with other idiots. And hang gliding is overwhelmingly populated and dominated by idiots. And I know Mark's an idiot 'cause I've corresponded with and read him and I know Mel's an idiot 'cause he uses a Hewett Bridle for non platform surface towing and doesn't use a Koch two stage....and don't get a lot of the "just do it" guys to listen to me (sound familiar, Tad?).
If Mel had been on the ground and OK with Bryan going up on the Greenspot - and he would've been 'cause he's a Hewett freak - then Mel needs to start understanding what a weak link is - and good luck getting through to him 'cause he's a Hewett freak.I plan to have lunch with Mel soon and try to talk him in to a little more process and a little less "go for it".
Mark's head needs to go on a platter.Do you all have any "things to say that work"?
- He was responsible for making sure this guy was qualified to participate in this activity before he put his name on the card, he was negligent in his responsibility, and as a consequence this guy is badly injured, out of the sport, and maybe permanently crippled.
- Mark was clearly advised on the danger of putting people up on fishing line and chose to disregard the warnings. And I have the correspondence safely archived on several hard drives - and I'll post it here so everybody can see it.
http://ozreport.com/forum/viewtopic.php?t=25321
Stop the Stupids at the USHPA BOD meeting
- These motherfuckers bloody well ARE in the business of keeping pilots safe. They establish policy, rate officials, instructors, and pilots, and dictate who can and can't fly.Mark G. Forbes - 2011/09/29 02:26:23 UTC
We can establish rules which we think will improve pilot safety, but our attorney is right. USHPA is not in the business of keeping pilots "safe" and it can't be. Stepping into that morass is a recipe for extinction of our association. I wish it were not so, but it is. We don't sell equipment, we don't offer instruction, and we don't assure pilots that they'll be safe. Even so, we get sued periodically by people who say we "shoulda, coulda, woulda" done something that would have averted their accident.
- I got blackballed out of the sport close to three years ago primarily for trying to get minimum weak link ratings established as policy and Bryan's arm is now in four pieces because of these evil sonsabitches.
Right now Bryan is badly injured, in a lot of pain, extremely depressed, feeling very stupid, and angry with and blaming himself. He needs to start understanding that this wasn't his fault - that he got fucked over by a megacorrupt, criminally negligent organization. And if he gets a GOOD lawyer (rather than a total idiot like the one the Priday family engaged) I can and very happily will work my ass off to show them how to sue those bastards out of existence - the way they should've been twenty years ago.It's not just concern for meet directors and policy makers...it's about our continued existence as an association. It's about minimizing the chance of our getting sued out of existence. We're one lawsuit away from that, all the time, and we think hard about it.
Note...
- 2011/01/15 - Shane Smith
- 2012/02/18 - Bryan
Separation of thirteen months and three days and one US state.
http://ozreport.com/forum/viewtopic.php?t=24846
Is this a joke ?
If those guys were both using twelve hundred pound loops of polyester line instead of little loops of fishing line to increase the safety of their tow operations they'd both probably be flying next weekend.Jim Rooney - 2011/08/26 02:44:10 UTC
Zach, you can nit pick all you like, but I'll put a 100,000+ flight record over your complaints any day of the week.
Let me see if I can clear up a few things for ya.
A lot of this I sent to Steve btw...
The "purpose" of a weaklink is not in question. Your semantics are.
The "purpose" of a weaklink is to increase the safety of the towing operation. PERIOD.
There are many ways in which it accomplishes this.
You're nit picking over what you call the "true purpose"... but all you're griping about is a definition... and an erroneous one at that.
Again, The weak link increases the safety of the tow.
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llwest@comcast.net
- Posts: 18
- Joined: 2011/01/26 14:30:47 UTC
Re: Broken arm Saturday for discussion
Bryan trained with Mark on a dolly, and I'm guessing they never taught him foot launching theory as pulling from the shoulders on foot launching is tricky. There is a dolly available about an hour away from town that we all share, but they wouldn't have been able to use it on that field Saturday as there were children's soccer teams practicing on both sides of the tow line about 100 feet away that the cart could/would have rolled in to (yeah, that is whole other source of "why, oh why" I am dealing with in my mind now). And everyone was ST rated and it was just going to be a short play day with just Mel and two "experienced" pilots on the new high-power winch.Meaning he foot launched. Do they not have or provide a dolly?
It was exactly that. Greenspot between the three-string and the tow line. I don't know if it was a single loop or a double loop yet.So - not that it's directly relevant here - what was it? I'm guessing a three-string with the lanyard also anchored at a shoulder loop?
I haven't heard yet which way it was routed. Under the tube would explain the aggressive nose-up if he wasn't prepared to deal with those forces but Bryan isn't up for conversation yet.Guess he went with the bridle under the basetube. (Not that that matters.)
Yeah. I don't know who else attended this surface tow clinic with him. I have heard that all the launches in AZ were from a cart, so he shouldn't have even attempted foot launching without a lot more education (IMHO). He got both his surface tow and aero-tow ratings at the clinic, so I am sorta glad he didn't start testing his aero-tow sign off here at 6000 feet behind a very fast trike.- Who's "THEY"? Mark?
Exactly. He's a veterinary surgeon too, so this going to impact his livelihood too.- Guess it's a no brainer that he is (was) right handed.
At first I wanted to write a complaint letter to Mark and USHPA, but he's so high up the chain that It probably wouldn't bother him or the org in any way and would just be alienating them, so I haven't done it yet and am just venting here to get it off my chest. I expect he has a good rationale for his decisions for what he does or does not teach and has a lot more experience than I do, although......All these guys with lots of experience seem to lead to lots of medical or funeral home business. Maybe it's just that they teach more and have done so longer, but......I wonder.
Speaking of "chest". The last time Mel was towed on the club's payout winch, he used his Koch setup, so he does prefer that to the Hewett himself. I've only seen him do Hewett a couple of times as a demonstration to others. I think he hopes everyone will eventually move over to Koch style.
Thanks for the conversation Tad.
Video of Mel towing up just before Bryan (who is walking in front of the camera at the beginning of the first video):
http://www.youtube.com/watch?v=g1PrroqVZ3g
-
Tad Eareckson
- Posts: 9161
- Joined: 2010/11/25 03:48:55 UTC
Re: Broken arm Saturday for discussion
My foot launching theory:...and I'm guessing they never taught him foot launching theory...
- Davis Link.Tad Eareckson - 2010/12/14 23:51:17 UTC
I think foot launch towing should be a felony - without a much better excuse than this situation indicated anyway.
- Foot launch.
- Paragliding bridle/release assembly under the basetube.
- Inexperienced Hang Two.
Upgrade any one of those issues Bryan can certainly or almost certainly fold up his Falcon and put it on the car by himself after the session.
Yeah, I'm calling the bridle under the bar.
He's gung-ho, he wants airtime, he's smart enough to know you can get higher with the bridle under, there's no downside to having it under at launch, and we know he was pitched dangerously high right off the bat."I did both and it doesn't make any difference."
Glad you didn't say "ST qualified". If they had been it wouldn't have happened....and everyone was ST rated...
Please tell me they were using a tow ring between the three-string and the towline.Greenspot between the three-string and the tow line.
What were the survivors using for releases? If they were using Kochs the weak link (if any) would been on the towline (and gone down with it) and there wouldn't have been a tow ring.
At least he did that much right.I have heard that all the launches in AZ were from a cart...
Given that there was a half decent reason for not using a cart and the conditions didn't appear to be any issue whatsoever, I don't have a particular problem with him foot launching - although, granted, that put his hands on the downtubes and didn't help with the pitch situation. (And, since nobody does hook-in checks, opened him up for the possibility of pulling a Floyd.) But he got off the ground reasonably OK....so he shouldn't have even attempted foot launching without a lot more education (IMHO).
I have HUGE problems with the release and the Davis Link, however.
That goddam Koch two stage has been around and doing a real good job for nearly three decades. And if it costs $350 you don't use the $35 second best option. That release would've paid for itself before the second hand had moved a twelfth of the way around the dial in the emergency room. Hell, it would've paid for a fair chunk of itself just by the time the downtubes folded.
I'm trying to figure out how the day could've ended much worse. A fast trike would've probably blown the Davis Link before the glider had budged.He got both his surface tow and aero-tow ratings at the clinic, so I am sorta glad he didn't start testing his aero-tow sign off here at 6000 feet behind a very fast trike.
My heart sank when I read that. I was hoping for left handed Walmart greeter.He's a veterinary surgeon too, so this going to impact his livelihood too.
It's astounding how stupid intelligent, highly accomplished people become when immersed in hang gliding culture.
That would be like writing a letter of complaint to the guy who's shaking you down for protection money and the regional mafia chief.At first I wanted to write a complaint letter to Mark and USHPA...
These guys are all really experienced and really good at doing things WRONG.I expect he has a good rationale for his decisions...
Experience counts for so very little with me in this game. Give me a dime's worth of common sense or logic over a thousand bucks worth of experience any day of the week. The only thing I despise more than experience is people who mention theirs....and has a lot more experience...
Exactly.All these guys with lots of experience seem to lead to lots of medical or funeral home business.
You needn't. These are almost all extremely simple, obvious, black and white issues....I wonder.
Good. He gets a few points back.The last time Mel was towed on the club's payout winch, he used his Koch setup, so he does prefer that to the Hewett himself.
Maybe he should pull his washout struts and disconnect his reflex bridle to demonstrate how early gliders used to kill a lot of people by diverging into full luff dives.I've only seen him do Hewett a couple of times as a demonstration to others.
Yeah. I hope everyone will eventually move over to straight pin style barrel releases. I stopped holding my breath about a dozen years ago and now understand that whenever glider people are given options for ANYTHING they'll flock to the shittiest one like flies.I think he hopes everyone will eventually move over to Koch style.
If I were running a winch I'd say...
You wanna fly? You use a Koch. I have a couple of loaners here you can use a couple of times. After that... Buy one.
I think they'd sell themselves - especially if I kept them in boxes with an X-ray of Bryan's arm pasted on the top.
Thanks for the very valuable data.Thanks for the conversation Tad.
There's a real opportunity here to do some real damage to USHGA - IF Bryan wants to keep what happened to him from happening to a bunch of someone elses.
http://www.kitestrings.org/post272.html#p272
I recommend that you minimize your direct involvement in anything that may happen. They've already done everything they can to me and I have nothing to lose. And they know it and they're afraid of me. And they're extremely vulnerable on this one.
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Tad Eareckson
- Posts: 9161
- Joined: 2010/11/25 03:48:55 UTC
Re: Broken arm Saturday for discussion
http://groups.yahoo.com/group/TUGS/message/927
weak link material question
weak link material question
http://groups.yahoo.com/group/TUGS/message/928Mark Knight - 2008/04/21 21:45:52 UTC
Tempe
Can someone tell me if they have seen or used the white line with the green stripe that they sell at Cableas Sporting goods for Aero-tow weak link.
I'm getting conflicting answers here.
Lable has printed on it:
Cabelas
Prestige
IGFA-class Dacron Fishing Line
Outsatnding for fishing and trolling
500 Yards
130 Lb. test.
It looks exactly the same as I've seen and used before.
Thanks,
Mark
http://groups.yahoo.com/group/TUGS/message/929Gregg Ludwig - 2008/04/21 22:46:04 UTC
not sure about that stuff. One of our pilots bought another brand of 130# dacron line that was clearly thinner than what I was used to and sure enough it kept breaking. The standard seems to be Cortland 130# green spot.
In Texas a weak link failure can be a real pain because of the hassle and expense of another tow. Because of the example above I will not use anything other than Cortland green spot. (on the other hand your product may work fine....it meets the specifications..)
http://groups.yahoo.com/group/TUGS/message/930Mark Knight - 2008/04/21 23:29:30 UTC
I would think it would be a good Idea to test every new spool of weak link anyway.
Yes...No?
http://groups.yahoo.com/group/TUGS/message/931Gregg Ludwig - 2008/04/22 00:04:48 UTC
testing not needed if you buy the same product. Sure there will be a slight variation. I tend to copy what the pro's do at Wallaby or Quest and they have been using Cortland green spot for years.
The stuff that did not work for us was:
Magibraid
Tournament grade dacron trolling line
meets IGFA lineclass specifications
offshore
300 meters
and I think it says 60 KG
(white with red and blue spots)
http://groups.yahoo.com/group/TUGS/message/932Michael Huckle - 2008/04/22 04:23:39 UTC
When you use this, is it used as a loop or as one "straight piece"?
If it was a loop then the breaking would be about 260 wouldn't it?
Thanks,
Mike
http://groups.yahoo.com/group/TUGS/message/935Gregg Ludwig - 2008/04/22 12:58:51 UTC
yes it's looped on the standard configuration....one would think this equals 260#..but it is much closer to 130# or so.
http://groups.yahoo.com/group/TUGS/message/937Tad Eareckson - 2008/04/23 11:06:57 UTC
I think there are about a dozen people in the world who really understand hang gliding weak links and Dr. James Freeman is two of them. The pros at Wallaby and Quest don't have a clue. Check out his explanation at:
http://www.dynamicflight.com.au/WeakLinks.html
Once you read and understand that page, life will get a lot easier, cheaper, safer, and more fun.
If you must use the 130 pound Cortland Greenspot, a double loop on the end of the bridle is a lot better one-size-fits-all than a single.
If you want to do weak links right:
http://www.tost.de/evers/edefault.htm
and put one of those on the back end of your tow line. Marco Vento (Portugal) is very happy using them in his ground based operation. A good source for the US is:
http://www.wingsandwheels.com/page30.htm
Also... Check out the shear links in my photos:
http://www.flickr.com/photos/aerotowrelease/?details=1
towards the end of the AT System Components set...
http://www.flickr.com/photos/aerotowrelease/sets/72057594141352219/detail
...particularly the bridle link.
If you're also registered with skysailingtowing you can check out the documentation in the "mousetraps" file. Otherwise, if you're interested, I can send you a copy.
A few of us are using shear links at Highland Aerosports (Ridgely, Maryland) very successfully.
http://groups.yahoo.com/group/TUGS/message/938Mark Johnson (rockspool) - 2008/04/25 00:21:17 UTC
I am very interested in trying to understand what you are trying to say.
1- You say in your opening that the pros at Wallaby and Quest don't have a clue. I have spent the last week at the Santa Cruz Flats competition watching, assisting and discussing the weak link issue with the tug pilots; Rhete Radford, Russell & Jim (Quest owners I believe), Jonny Thompson FAA Examiners and Tug pilot from Kitty Hawk, and a couple of others. I have read Dennis Pagen's book on towing, the Australian & Canadian towing manuals and the USHPA's. I also have looked at the links you have provided in your email and I have not found the discrepancies you have indicated. Would you be so kind as to very specifically point out what exactly you think the Quest Tug pilots are doing or not doing right so that I can understand.
2- You say "If you must use the 130 pound Cortland Greenspot, a double loop on the end of the bridle is a lot better one-size-fits-all than a single" Which end are you referring to?
http://groups.yahoo.com/group/TUGS/message/939Gregg Ludwig - 2008/04/25 00:40:06 UTC
Rockspool-
You are not the only one that has great difficulty trying to understand what is written in the tadercksn posts or links. You should now have all the answers you need after spending time with the pro's at Santa Cruze Flatts.
Gregg Ludwig
ushpa AT Administrator
Mark Johnson - 2008/04/25 00:47:20 UTC
Thanks,
Mark
http://groups.yahoo.com/group/TUGS/message/943Tad Eareckson - 2008/04/25 13:09:29 UTC
Mark,
I don't know what's been going on at the Santa Cruz Flats but the number of weak link breaks you should've seen should've been ZERO. Any more than that and somebody screwed up bigtime in one of two ways:
1. Selecting a weak link of inadequate strength; or
2. Waiting all freakin' afternoon to pin off from a lockout.
And it's pretty much always gonna be: 1.
Here's one of the things wrong with, for the moment, Quest...
http://www.questairforce.com/aero.html
They THINK they're using 260 pound weak links. That's closer to what they SHOULD be using. But they're not. They're using something close to about HALF of that - just like Gregg says a few posts ago.
I'm guessing you haven't read the "mousetraps" file (nobody ever does) but it's got extensive explanations of what folk should be doing, why, and how to go about it.
The hang gliding culture thinks of weak links as lockout protection and insurance against releases that don't work (like the Bailey illustrated in the above link). They're not.
Yes - a conventional weak link MAY fail before you slam into the ground. (It also MAY fail in straight level flight for no reason whatsoever - we've all seen and experienced plenty of those.) But it doesn't have to and can't be counted on to do so. That's what the release is for.
If you look at the USHGA Towing Committee Guidelines:Yeah - that's what it should be for the top end - BUT IT NEEDS TO SAY SOMETHING ABOUT THE BOTTOM END TOO 'cause understrength weak links - in practice - are a lot more dangerous than overstrength ones.The weak link at the glider end of the tow line must have a breaking strength such that it will break before the tow line tension exceeds twice the weight of the hang glider pilot and glider combination.
So you go to the FAA and see what they say for sailplanes. Same top end - 2.0 Gs, bottom end - 0.8 Gs.
So - if you're me - you say, "OK, let's split the difference and put it smack dab in the middle of the safety range" and come up with:
1.4 Gs
The weak link is there for ONE reason - to keep the plane from breaking if everything else goes wrong. It should be thought of as something that NEVER breaks. It should be thought of and used the same way you do your parachute. You want to have it available but you don't EVER use it.
(OK - it's also important in that it limits the load to which the release is subjected but we can ignore that for the purposes of this discussion.)
This is a tough concept for a hang glider pilot to get 'cause you've got to chuck most of what you've learned from "Towing Aloft" and everything. It took about two years to sink through my skull.
Try this exercise - Try to recall an instance of yourself or anyone you've ever known saying - after suddenly losing connection to the Dragonfly - "Boy am I glad that weak link popped." They don't say that. I'm probably not supposed to print what they actually and invariably say.
Dynamic Flight:
http://www.dynamicflight.com.au/WeakLinks.html
ABSOLUTELY NAILS IT.
Also, check out some of these discussions:
http://ozreport.com/3.047
http://ozreport.com/3.048
http://ozreport.com/3.066
http://ozreport.com/9.032
http://ozreport.com/9.033
(The stuff about "strong links" endangering tugs is bullshit. You can stall out a tug with the flimsiest of weak links and a double loop of Greenspot is no more dangerous to it on a solo glider than it is on a tandem.)
With respect to Question 2...
Put a double loop of Greenspot on the top end of your two point bridle and BOTH ends of your secondary / one point (shoulder to shoulder) bridle.
And don't use curved pin barrel releases if you want them to be operable under load. See the Temp set at:
http://www.flickr.com/photos/aerotowrelease/?details=1
http://www.flickr.com/photos/aerotowrelease/sets/72057594066212198/detail
Cache
Thanks very much for your interest,
Tad
http://groups.yahoo.com/group/TUGS/message/944Mark Knight - 2008/04/25 15:05:46 UTC
One more question on weak link strength.
If we are using 130 lb test.
Does the weak link strength increase by multiples of 130 by the number of strands.
see picture:
http://www.knight3.net/hangglide/weaklinks.png
Is this correct?
How much trouble are we asking for by doing multiple loops?
Snags, loop overs and hang ups?
-
I have read moustraps. All info is good.
I guess we have to look it over and decide for ourselves what we want to do.
I use the barrel type and the 3 string release for aero and scooter towing.
I'm not discounting anything said so far, and listening very carefully.
One of the guys here tested the Cabelas 130 lb test and it consistantly breaks at 80 pounds.
This is one loop.
Fish stories;
I guess Cabelas line lets you tell your friends how big the one that got away was.
"It broke 130 lb test line. IT was Huge!
http://groups.yahoo.com/group/TUGS/message/945Jim Gaar - 2008/04/25 16:42:47 UTC
Try the 130 test "kite" string. It's 8 strand poly weave I think. Worked for 5 years flawlessly on solo AT with a 150+ foot poly towline, center of mass open V bridle with primary and secondary releases.600 tows without a hitch.
It's not rocket science folks. 8 inch piece, single loop with opposing single grapevine knots for solo, 16 inch piece with double loop for tandem.
YMMV
http://groups.yahoo.com/group/TUGS/message/946Mark Knight - 2008/04/25 17:10:50 UTC
Where are you buying it?
Who is the manufacturer?
What is the part number?
Not rocket science agreed.
I don't want to buy another sub rocket standard spool of waiste product.
There are obviously differences from manufacturer to manufacturer.
Thanks
http://groups.yahoo.com/group/TUGS/message/947Tad Eareckson - 2008/04/25 17:45:42 UTC
Mark,
I can't begin to tell you how incredibly happy I am that somebody has FINALLY taking a thoughtful look at this stuff. Makes me optimistic to think that the last decade and a half of my life hasn't been a total waste.
Anyway...
Generally speaking, whenever you put a knot or sharp bend in a piece of line you knock off forty to fifty percent of its rating.
So no - those multiples of 130 you're using are useless 'cause you need to secure that stuff somehow.
Let's limit the discussion - for the moment - to 130 pound Cortland Greenspot installed on Spectra hollow braid bridles.
I haven't tested odd increments (1, 3, 5) 'cause you can't Lark's Head them onto a bridle eye.
I get about 128 to 147 for a single loop, 200 for a double, and 359 for a triple.
I haven't tested beyond that but would speculate that the predictability will start going to hell 'cause there may be uneven seating of the loops and, thus, loading on the strands.
I wouldn't, however, worry any more about fouling with multiple loops than I would with a single.
But I'm not just not real interested in Greenspot 'cause these shear links are the best thing since sliced bread.
I've developed one version of them for use on the ends of the tow line but those have had very little field testing. The one at the tug end will be OK but I'm not sure how well the one at the glider end will hold up to being dragged day after day. The Tost weak link is kinda heavy and overbuilt for our purposes but that is probably the way to go.
The ribbon bridle is excellent but it takes the better part of a day to punch one out and a spinnaker shackle (which is a lousy glider release anyway) will chew up the shear link on the top end.
If you tow one point, however, the bridle link can't be beat. It's cheap, easy to make, and will last forever.
Thanks again for your interest. I will remain more than happy to answer any questions I can.
http://groups.yahoo.com/group/TUGS/message/948Tad Eareckson - 2008/04/27 12:44:11 UTC
Mark,
Haven't heard from you in a bit and I'm gonna shift back into Hyde mode.
DO NOT - UNDER ANY CIRCUMSTANCES:
1. GET YOUR ANSWERS BY SPENDING TIME WITH THE PROS;
2. "DECIDE FOR YOURSELF WHAT YOU WANT TO DO";
3. EVER make a decision based upon WHO is giving you information - including yours truly.
Instead...
When in doubt - follow the rules.
Next - understand the science and theory behind the rules to know which ones are valid and which ones ain't.
These "pros" that keep getting referenced are professional PILOTS - they're not scientists or engineers, they're not following the rules, they don't understand the rules, and they're getting people hurt and killed.
Stupidity and insanity are contagious diseases and the AT culture is a massive case of the blind leading the blind.
I did hop on the Oz Report to see what was going on at Santa Cruz Flats. The number of weak link breaks were having was NOT zero - which is what it would've been for a sailplane meet.
http://ozreport.com/12.081
Weaklinks - the HGFA ruleshttp://ozreport.com/12.080Davis Straub - 2008/04/22 14:47:00 UTC
Here is the requirement from the 2007 Worlds local rules (which I wrote) for weaklinks:Pilots must use weaklinks provided by the meet organizers and in a manner approved by the meet organizers. All weaklinks will be checked and use of inappropriate weaklinks will require the pilot to go to the end of the launch line to change the weaklink.
Weaklinks will consist of a single loop of Cortland 130 lb Greenspot braided Dacron Tolling line and should be placed at one end of a shoulder bridle.
No one makes it back - Santa Cruz Flats Race, day twohttp://ozreport.com/12.083Davis Straub - 2008/04/22 06:02:32 UTC
We were launching in light cross winds. I got on the cart but noticed that the back was too high. I ignored it and off we went. Then the glider was stuck to the cart. I finally jiggled it off the cart, but zoomed right up and blew the weaklink. Now I had to land down wind or cross wind. I tried hard as I could to get the glider to turn into the wind, but no luck (as I was only twenty feet high). So I just flared at the last second and that worked, although I was covered in dust.
I was not the only one breaking weaklinks as it seemed for a while every third pilot was having this problem. You've got to get the keel cradle set right.
Dusty - Santa Cruz Flats RaceA WEAK LINK IS NOT THERE TO KEEP THE GLIDER FROM HITTING THE GROUND. IT'S THERE TO KEEP IT FROM BREAKING UP IN THE AIR.Davis Straub - 2008/04/24 17:11:39 UTC
A novice competition flex wing pilot (who almost ran into me yesterday coming into the thermal smack dab through the middle of the thermal), broke a weaklink on his second tow very low and got off at 300' on his tow. So that was further discouragement.
None of those gliders were in the remotest danger of breaking up.
(None of those gliders were in the remotest danger of hitting the ground, either.)
None of those weak link breaks made the tow safer - they made things more dangerous for the glider.
ALL of those breaks were undesired. If the pilots had WANTED to be off tow they'd have gotten off tow.
USHGA - and the FAA - say that a weak link up to 2 Gs is safe and appropriate. That means the glider will be pulling 3 Gs at the point of failure.
THESE gliders were not pulling 3 Gs. They were not pulling 2 Gs. They were pulling maybe 1.5 to 1.8 Gs.
They were using those STUPID single Greenspot loops that everybody "thinks" are appropriate for all solo gliders on the planet regardless of their weights. If EVERYBODY had had double loops, that meet would've gone a lot smoother.
By the way...
I'm pretty sure that one of those gliders was still using the same 1.1 G bridle link I gave him nearly a year ago (it happens that he IS a professional - if that makes you any happier).
Also from the Oz Report...
http://ozreport.com/12.083
SkytingThese IDIOTS haven't figured out yet that the way to make the one point ("pro tow") bridle infallible is not to make it thicker/stiffer (although that helps) but to make it TOO SHORT TO BE CAPABLE OF WRAPPING.Davis Straub - 2008/04/24 14:15:22 UTC
The pro tow and the "Moyes" type system require that the bridle go through the "ring" at the end of the tow line if the weaklink breaks. They are therefore not infallible. Other weaklink release systems are also not infallible. Infallible is a pretty high barrier, and we might want to speak of more or less fallible.
Putting weak links at BOTH ends of the bridles (like I told you in my previous post) also makes them infallible.
The solutions to all of these insane discussions are all documented and illustrated in the "mousetraps" file and the:
http://www.flickr.com/photos/aerotowrelease/?details=1
website and have been flying at Ridgely for years. But nobody bothers to look at or consider them.
My system IS infallible. So is Peter Birren's.
One more thing for the time being...
That barrel release you say you're using is DANGEROUS.
Here's the USHGA Aerotowing REQUIREMENT:Assume a 1 G weak link - for you - and run the test. Hell, just run the test at half the load. See what happens.The release must activate with zero tow force and at a tow force twice the weak link strength.
Don't do what everyone else is doing. Follow the rules.
http://groups.yahoo.com/group/TUGS/message/949Mark Knight - 2008/04/27 15:08:22 UTC
I was at the Santa Cruz Flats comp every other day this past week.
I don't understand why you say they should never break?
If they are truley a weak link, shouldn't they be close to breaking tension as a safety feature.
I would rather have a ocasional break and something that breaks easily when things go bad.
This is purpose of a weak link.
I have had a great time talking and listening to Rhett and Johnny about tugging.
2 great guys. I hope to fly with Rhett this afternoon.
I have seen a few things I would change in the system but thats my openion.
I have a few of the Weak links they were using and will test them just for the fun of it.
I decided to use two barrel releases, (one on each side of my harness. I don't think anything is in-falable, but planning on if things go wrong, what are you going to do is best.
Work through a senarios in your head over and over. Practice.
http://groups.yahoo.com/group/TUGS/message/950Tad Eareckson - 2008/04/27 19:25:32 UTC
Mark,
I don't think I've crossed paths with Rhett but I've known Jonny Thompson intermittently over the course of the past 26 years and have a very high opinion of him. I once saw him save a life by hitting the gas on a winch at a critical moment. Well, I didn't actually see him do that 'cause I was running full speed to shore 'cause the glider was about to slam into the dock right at the point I had been standing. But I've never had any conversations with him on any of the issues at hand.
Anyway...
You are TOTALLY NOT GETTING IT with respect to the weak links. I am - however - very sympathetic 'cause, as I said, it took me about two years of reading, questioning, thinking, and forgetting everything I ever "learned" from the hang gliding culture before the light bulb started glowing and finally lit the room.
Too bad you didn't talk to Sunny. I spent an hour talking to him a year ago and at the end of the conversation he requested that 1.1 G bridle link I mentioned earlier.
I don't know how many tens of thousands of tows they've in their decade of operation but when I next see him I'm gonna ask if they have EVER had a flight which would have been endangered by using a double loop of Greenspot. I expect the answer to be - no.
I started flying a 1.4 G weak link at the beginning of last season and I can't tell you how much better I feel about towing.
I used to always be holding my breath until I got a hundred feet off the ground and in a near panic every time I bounced through a little rough air. I've had really good flying days ruined by multiple breaks.
I now go up with the best release system in the world, there is ZERO possibility that I won't be off tow a millisecond after I twist my left hand, and I plow through severe turbulence without a care in the world.
Your statement:is just flat wrong. I know you read it in Towing Aloft. That stuff is just flat wrong too. You need to go back to the links I provided and understand what's being said.This is purpose of a weak link.
If you do nothing else just go back to:
http://www.dynamicflight.com.au/WeakLinks.html
and read and UNDERSTAND that first sentence. That's really everything you need to know.
Then just FOLLOW THE RULES and use a 1.4/1.5 G weak link and you're done.
This sentence:is meaningless. The breaking tension of what?If they are truley a weak link, shouldn't they be close to breaking tension as a safety feature.Wrong. Preflighted cross spars, leading edges, downtubes, basetubes, side wires... are infallible. The preflighted release systems that Peter Birren, Steve Kinsley, Tim Hinkel, and I have developed are infallible.I don't think anything is in-falable...
You can practice all you want but if you're relying on barrel releases that are inoperable under load you can end up dead anyway. See the skysailingtowing post 6585. They fail the performance tests (double the "50 pounds" - that was an error). In electing to use them you are choosing to violate the rules.
Earlier you said:but I'm a lot less elated now because I realize you don't understand it.I have read moustraps. All info is good.
If you want to work on remedying that maybe we can make some progress on the phone and I can walk you through things with the photos in front of you. Lemme know and we can arrange a time.
http://groups.yahoo.com/group/TUGS/message/951Tad Eareckson - 2008/04/28 12:45:09 UTC
OK, try this analogy...
Remember this statement? -Lemme expand on that.Tad Eareckson - 2008/04/25 13:09:29 UTC
The weak link is there for ONE reason - to keep the plane from breaking if everything else goes wrong. It should be thought of as something that NEVER breaks. It should be thought of and used the same way you do your parachute. You want to have it available but you don't EVER use it.
The functions of the weak link and parachutes are EXTREMELY similar.
We all carry a few pounds of silk around with us. We never use them and when we do it's about a coin toss as to whether or not they're gonna do us any good anyway.
We mostly need them for one of three reasons...
1. We fly in tight little kettles of swirling aluminum and we and our buddies aren't always looking where we're going.
2. On rare occasions we get dumped so violently that our tailless aircraft tuck, tumble, and break.
3. The placards on our keels get scuffed off by dolly tail supports and we forget about the thirty degree plus or minus pitch and sixty degree roll operating limitations.
And it's pretty much always gonna be: 3. So let's ignore 1 and 2 for the purposes of this discussion.
The purpose of a weak link is to FAIL just BEFORE the glider breaks.
The purpose of a parachute is to WORK just AFTER the glider breaks.
Ideally we would want the parachute to work just BEFORE the glider breaks also. We COULD do that.
We could take an accelerometer, some coat hangers, double A batteries, a blasting cap and rig something up so's the chute would blow as soon as you exceeded six Gs - assuming the glider would buckle at seven.
That way the probability that the parachute would actually work would go way up - as it wouldn't have to make it out past a swirling junk heap of wires and broken aluminum - and you wouldn't have to buy a new glider every time you pulled up too hard from the bottom of a loop.
BUT YOU DON'T WANT TO SET THE ACCELEROMETER TO 2.5 OR 3 GS - even though that would be a pretty good indication that you had exceeded the operating limits of your aircraft. 'Cause that could put you on down at a time and place not of your choosing for no good reason - and there's stuff like wind, trees, power lines, rivers, and alligators down there.
The weak link IS an accelerometer which also makes the decision for you that the TOW - but not the FLIGHT - is over.
A 1.4 G weak link tells you that the tow is over at 2.4 Gs. Even though the glider is nowhere near feeling threatened - that's fine. 'Cause by that point you're so far out of whack that there's no freakin' way you're gonna salvage the tow anyway and you've obviously suffered a stroke 'cause there's no reason you shouldn't have released five minutes ago when you reached the point of no return.
You have stated -There are a LOT of problems with that.Mark Knight - 2008/04/27 15:08:22 UTC
I would rather have a ocasional break and something that breaks easily when things go bad.
Things can go VERY VERY BAD with VERY VERY LITTLE TOW LINE TENSION.
Anything that breaks easily enough to ensure that you will not get into a bad situation is also something which will not survive the acceleration of the cart - which is where maximum loading occurs in the course of a normal tow.
Those occasional breaks that happen for no good reason - like ALL of the ones that occurred at Santa Cruz Flats and virtually ALL of them anywhere - DO NOT MAKE THE TOWS SAFER. THEY MAKE THE TOWS MORE DANGEROUS.
They drop people on the ground at times and places not of their choosing - occasionally in crosswinds, thermal generated tailwinds, and meteorologically and propeller driven turbulence.
They necessitate extra launches and landings and those operations are DANGEROUS.
And I don't want you and your 0.50 to 0.75 G weak links at the airport on a day that I want to fly. Those relaunches clog the flight line, eat gasoline, raise the price of my lift ticket, melt my icecaps, and cause me to miss the soaring window.
And if you lack the skills and confidence to react to a situation LONG before even a flimsy weak link can cut in and choose to use substandard release systems for which you mistakenly believe a substandard weak link can be counted on to compensate - you have no business behind a tug anyway.
It all boils down to...
Follow the rules.
http://groups.yahoo.com/group/TUGS/message/952Tad Eareckson - 2008/04/28 23:26:49 UTC
Oops, I got my Marks - Johnson and Knight - confused. No real problem with respect to substance but - sorry 'bout that.
Jim,
When you talk about five years / six hundred solo tows flawlessly / without a hitch - what, exactly, does that mean?
Does that mean you NEVER had an unnecessary/undesired weak link break?
I would define a flawless run of tows as one in which there were ZERO weak link breaks and in which any glider which found itself in an unrecoverable situation released from tow well before a weak link would have come into play.
If the operation was - indeed - flawless one would never find out aloft how suitable those weak links really were. Kinda like if an aerobatics competition comes off without a hitch one never gets a feel for the effectiveness of a particular parachute. But...
THERE IS NO SUCH THING AS A SOLO WEAK LINK.
A weak link - if you go back to THE RULES - is selected in relation to the particular glider for which it is to be used. It is measured in pounds and best thought of in terms of a G rating.
A solo glider can be a lightly loaded Falcon 140 - 162 pounds - or a heavily loaded Talon 150 - 354 pounds. The little one is well under half the weight of the big one.
YOU CANNOT USE THE SAME WEAK LINK TO MAINTAIN THE SAME MARGINS OF SAFETY FOR THOSE TWO BIRDS.
And - likewise - the top end solo glider can overlap a lightly loaded tandem ride.
Weights are not graduated in two increments - solo and tandem. They're measured in POUNDS.
This sure ain't rocket science - this is grade school arithmetic. But we've gotten away from the basics.
Here are the basics:
http://www.birrendesign.com/rhgpa_criteria.html
NOTE THE TITLE OF THAT PAGE (as I just did).
Caveat...
As Peter Birren noted on the Oz Report three days ago, the Skyting Criteria have been around a lot longer than the Dragonfly. Here's where you have to understand the science and theory behind the rules to know which ones are valid and which ones ain't.This, we may have noticed, is in conflict with what the USHGA Tow Committee, the FAA, Dynamic Flight, and yours truly are saying.#7: INFALLIBLE WEAK LINK
...not to exceed 1G...
Those criteria were written when the best tow equipment and releases available tended to be primitive and unreliable and Donnell Hewett was treating the weak link as an emergency release. It ain't - and if you think of it and ask it to function as such you're asking for trouble.
I would eliminate the reference to pilot experience and regard the 1G figure as the MINIMUM for use in the AT environment - not the maximum.
And - as long as I've started nipping at sacred cows...
The concept promulgated in Towing Aloft that, because the line tension involved in aerotowing is less than that in surface based towing, the weak link rating must therefore be reduced in proportion is bullshit. They've got it totally backwards.
Surface based towing tends to be tension controlled and thus - if things are operating normally - there's no way to break a weak link.
Aerotowing is speed controlled. Yeah, the direction of the pull is more in keeping with the direction you want to go (up), and thus the tow is more efficient and the tension is less. But when you get hit by something and/or start getting out of kilter - the needle starts swinging all over the place. There's no winch assembly to dampen things out.
You need a much STRONGER weak link to make it up through any air worth flying in.
OK, that's pretty much all I've got to say on the issue. It would be nice to hear some discussion but I know I've got a few people listening and - hopefully - thinking 'cause the clicker on my photos site keeps creeping up.
http://groups.yahoo.com/group/TUGS/message/953Mark Johnson - 2008/04/29 04:15:39 UTC
This question is for Aero Towing only.
Assuming a 250 lb total pilot hook in weight, the forces most say are on the end of the rope depending on who's manual you are reading range from 60 to 80 lbs. So for my question, the assumption is that the glider under tow is operating in smooth air and a steady towing condition. I assume then the glider in this configuration is stressed to 1G (250 lbs) with lets use a 80 lb tow force. Someone correct me if my assumption is wrong. Also lets assume the weak link is on the end of the tow rope in front of the pilots bridle.
Here are my Questions
1) Most aero towing guidelines state to use a weak link in this configuration of 80% to 100% of pilot hook in weight, which would equal 200 lb to 250 lbs of breaking strength, correct?
2) If 80 lbs of tow force is equal to 1G or 250 lbs of stress on the glider, then would a 80% weak link equal 2.5G's, and a 100% weak link equal 3.1G's, correct? or is it some other formula? if so please advise.
http://groups.yahoo.com/group/TUGS/message/954Tad Eareckson - 2008/04/29 13:05:33 UTC
Mark (Johnson),
Oh good - positive evidence that I'm not just talking to myself.
OK, for starters - you don't EVER talk hook in weight when you're talking tow tension and weak links. You talk about how much more the dolly weighs when you're proned out on it. You have to throw in the glider.
As luck would have it my hook in weight DOES happen to be close to 250 pounds and I DO have test data from several flights on my HPAT 158 - VG (full) on. Together we put about a 320 pound load on the dolly.
I don't know whose manuals you're reading but the ONLY published data on the in flight tow line tension I know about is mine - in the mousetraps file (which you REALLY oughta read if you want to understand this stuff). AND IT SURE AIN'T 60 TO 80 POUNDS.
Behind a 914 Dragonfly it's 125 pounds - 155 with the turbocharger kicked in (310 pound glider at the time).
At this time I don't know how that tension is effected by the particular glider but I've been leaning towards it being constant - the 914 puts out the same pull and gliders go up at different climb rates depending upon their weights and lift to drag ratios.
There's a very smart engineer who flies at Ridgely who disagrees with me however. I've been itching all winter to get the data off of a heavy tandem tow. That should give us a pretty good idea what's going on. (I JUST missed the opportunity at the close of last season.)
Anyway...
Yeah, your assumption is wrong.
A glider boating along in smooth air is feeling 1 G. Let's make it me. The glider is not just lifting me - it's gotta lift itself at the same time. 320 pounds currently - 1 G.
Behind the tug - which is level with the glider - in addition to feeling 320 pounds of gravity - straight down - it's also feeling 155 pounds of tow tension - straight ahead.
So you draw the vertical and horizontal vectors and take the resultant and get 356 pounds - 1.11 Gs - and the glider now thinks gravity is about 26 degrees forward of straight down and adjusts its pitch accordingly.
I REALLY like your assumption that the weak link is on the end of the tow line - that's a REALLY good place for it.
No. Again - aerotowing guidelines do not talk about hook in weight. They talk about total system weight.
And I don't know what you mean by "Most aero towing guidelines".
The Skyting Criteria were developed, as I just said, prior to aerotowing. They specify a 1 G upper limit and have winches in mind.
Towing Aloft specifies a 0.8 to 1.0 range. Every other page of that book needs to be shredded.
The current USHGA AT Guidelines define a 2 G upper limit (but no lower).
The FAA - which is who you oughta be listening to (along with Dynamic Flight) - REQUIRES a point within a 0.8 to 2.0 G range. But hang gliders are a BITCH to control on tow relative to sailplanes so you don't wanna be anywhere near the lower end of those figures.
I say select a weak link in the middle of that range - 1.4 Gs. Dynamic Flight says 1.5 Gs - close enough. With those ratings your glider will be well protected and the only time you're gonna find yourself off tow is when you really want to be off tow. And you're gonna be able to release long before the weak link will fail.
For 1.4 G weak link protection for my 320 pound glider I want the weak link on the end of the tow line to be rated for 448 pounds.
If I'm gonna rely on weak links on a two point bridle I want 258 pounds on the top end and - in case it wraps on the tow ring - about 300 pounds on the bottom. The first figure is more than half of 448 pounds because the bridle is under more than half of the tow line tension 'cause there's an angle of about sixty degrees at the apex. The bottom end is beefed up a bit 'cause you REALLY don't want that one blowing first.
Weak links on BOTH end of a secondary bridle should be half (224 pounds) of the maximum tow line tension 'cause that apex angle is pretty acute and thus the load increase is negligible.
With 1.4 G weak link protection you're going to be adding what you and the glider are contributing to the forces - 1 G - to the maximum that the tow line can add - 1.4 Gs. Total 2.4 Gs.
Actually, if you're locking out you could pull a good chunk of an extra G to add to the load on the glider. So if you wait a LONG time to release you could maybe exceed 3 Gs. But it ain't gonna break until after six so don't worry about it - the weak link will have been long gone no matter what you do - or don't.
http://groups.yahoo.com/group/TUGS/message/955Tad Eareckson - 2008/04/29 14:02:13 UTC
Damn. I plugged in the turbocharged tension for those calculations.
Let's do it again for 125 pounds.
The glider is lifting 344 pounds, pulling 1.07 Gs, and pitched up an extra 21 degrees.
http://groups.yahoo.com/group/TUGS/message/956Mark Johnson - 2008/04/29 14:46:30 UTC
Whops, sorry I did mean total hook UP or hook On weight (glider included) not hook in weight. So using your numbers, you have 320 lbs with a 158 lb tow force.
1) How did you come up with the 356 lbs, I mean how is that calculation determined? I understand how you converted 356 lbs to 1.1 G's but how did you figured 356 lbs?
2) If in your case 158 lbs of tow force = 1.1 G on the glider (based on your hook-UP or hook-ON weight of 320 lbs), lets assume a weak link strength of 1G or 320 lbs. This means that the tow force in your case is equal to 44% of the increased 1.1 G load of 356 lbs (158/356=44%), or 49% of the HookOn weight (158/320=49%). So what would be the load factor on the glider at the point the weak link hit its breaking point of 320lbs? Is it correct to assume it would be double or 2 G's when it broke?
Tad Eareckson - 2008/04/30 12:29:53 UTC
Mark (Johnson),
OK, let's back up a bit...
The 155 pound tow tension figure was for the Rotax with the afterburners kicked in. At Ridgely anyway, they reserve those for tandem tows and not necessarily, I believe.
The tension I recorded for myself - 320 (310) pounds - under steady tow with normal engine power was about 125 pounds.
So in normal flight the glider is feeling the large evil gravity force straight down and the lesser but heroic tow force straight ahead ('cause you've got the Dragonfly on the horizon).
So you represent them as vertical and horizontal vectors, make a rectangle, and draw the diagonal - just like in the parts of Towing Aloft that shouldn't be shredded.
Like this (in a monospaced font):
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| \
| |
| \
| |
| \
| |
v
The magnitude of the diagonal you determine by ignoring half of the rectangle and treating it as the hypotenuse of the resulting right triangle - the square root of the sum of the squares of the gravity and tow forces.
Then you determine the angle using a trigonometric table. If you can't find one you cheat (like I did) and just use a protractor.
You don't need to do your first equation - tow force over the slightly increased loading the glider is feeling under tow 'cause the weak link is already feeling and taking care of that and that number - 344 for the 320 glider and 125 tow - becomes totally meaningless/irrelevant as soon as the situation starts going the least bit south.
Yeah, the rule of thumb is you just add the G rating of the weak link - 1, in your example, to your hook up weight - also 1 - and get 2.
As I said earlier, if you're locking out in something resembling a coordinated turn the weak link will not fail until the glider is actually feeling something over those theoretical 2 Gs, but don't worry about it. You can take 6 Gs before you need to start worrying and THERE'S NO FREAKIN' WAY even a 2 G weak link is still gonna be around beyond 4 - try as you might.
I suspect that if you use even a 1.0 G weak link you can get away with never breaking it. I am damn near positive that a 1.4 G weak link will never break as long as you're doing things some small percentage of right at your end of the line.
http://groups.yahoo.com/group/TUGS/message/959Joe Street - 2008/04/30 15:23:28 UTC
Tad;
I'd like to comment on some of your statements based on the experiences I've had. My hook-in weight is around 180 lb and my glider weighs 63 lb so 1 G for my setup would be 243 lb. We have for years been using braided trolling line which is rated to 130 lb "test" for what that's worth. I have never broken a weak link but others heavier than me do on occasion.
In all this discussion I haven't seen much talk about how placement of the weak link comes into play with the forces. Correct me if I am wrong but I am thinking that using a V bridle as I do and placing the weak link at the end up by the hang point means that the weak link sees roughly half of the tow force. I say "roughly" because there will be some friction where the bridle runs through the ring on the end of the tow rope which may allow a small difference in tension on either side but the tow ring should slide along the bridle to the point given any tow scenario where tension is almost equal on the upper and lower sides of the vee.
I use a single loop of the weak link material and arrange it so the knot in the loop lies within a lark's head knot which secures the weak link loop to the end of my bridle. This ensures that the tesion on the knot (forming the weak link loop) is less than it would be if positioned somewhere along the strands between the bridle and release.
I'm also assuming that used in this way I get close to double the 130 lb breaking strength of a single strand although it will be somewhat less, but let's say for argument that I do get 260 lb breaking strength for a single loop. This is what would be considered, according to the previous discussions, as a 260/243=1.07G link for me on my glider. Now regardless of whether it is placed at the top of a V bridle as I do or at one (or both) shoulder on a 'pro tow' setup, because of the V in the bridle, the tow rope would have to see something like 260*2=520 lb in order for the single loop weak link to see the 260 lb required to break it, right? So doesn't that mean that putting the weak link at the end of a V-bridle rather than right on the tow rope itself means that the G rating of the link is considered as double the all up weight as I have shown? So my 1.07 G link is actually a 2.14 G link? That would explain why I have never had one blow even on a strong days where I have had the tow rope snap tight after an upset has led to a disturbing loop of slack between me and the tug.
Others have had a surprise breakage but I notice is is generally with heavier pilots with the single loop and often due to the knot breaking or coming undone. Many people do not purposely place the knot within a lark's head as they attach the weak link to the bridle as I do, but simply grab a weak link and tie it on to the bridle in some random fashion so the knot in the loop ends up somewhere random as a result.
I'm interested to hear your comments on these thoughts.
Joe
http://groups.yahoo.com/group/TUGS/message/960Gregg Ludwig - 2008/04/30 20:24:53 UTC
A single loop, as described above, in a typical bridle configuration will break at about 145 pounds. This value was obtained with testing and reported by Tad and others.
http://groups.yahoo.com/group/TUGS/message/961Gregg Ludwig - 2008/04/30 20:29:09 UTC
sorry..above perhaps not very clear. The weak link described above will break at about 145 pounds but the tow line force would be much more because of splitting the force with a V bridle.
http://groups.yahoo.com/group/TUGS/message/962Mark Knight - 2008/04/30 20:38:20 UTC
In climbing and other knotty sports (LOL)
The knot is the weakest point and the attachment points get the most stress.
Putting the knot on the end or in the larks head would put it at a high stress point and would increase your chances of breaking it at the knot. Would it not?
http://groups.yahoo.com/group/TUGS/message/963Mark Johnson - 2008/04/30 20:36:52 UTC
Yes you are correct. Any time the tow force is split it reduces the force by half. In the case where there are 3 attachment points (Glider & both pilot shoulders) means that the tow force is 50% on the glider and 50% to the pilot split into 25% on each shoulder. If the glider weak link breaks then you have 50% on each shoulder. In the 3 attachment point setup, Jim at Quest recommended to me (assuming I understood him correctly) that you should have a 2 line weak link on the glider and 1 line weak link on each shoulder. That way if the glider weak link breaks you now have the full load split between both shoulders and could still continue the tow and still have the proper weak link protection on both shoulders.
In my opinion there should be a weak link at every connection point on the glider and pilot if you do not have one on the end of the tow rope before you clip in. That is why I believe the manuals call for a weak link on the end of the tow rope so that no matter what the pilot does or screws up in his bridle setup, it can all fail and by having a weak link between the tow rope and your hook in means that your still protected.
http://groups.yahoo.com/group/TUGS/message/964Mark Johnson - 2008/04/30 20:41:00 UTC
Not according to the manual, they say to put the Larks head in the Loop Head. I think it actually reduces the pressure on the knot, but I am not positive, just know that is how the manual show to do it.
http://groups.yahoo.com/group/TUGS/message/965Tad Eareckson - 2008/05/01 11:52:18 UTC
Damn - again. The web version of my previous post spit out all of the spaces in my little vector diagram. Lemme try it again with periods.
.-------->
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|.|
|..\
|...|
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|.....|
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v
Joe,
Yeah, like Gregg says (and contrary to what Quest says), you get something a lot closer to 145 pounds with that loop. Lemme use 140 just 'cause that's the number I picked for my standard.
I guess I could say - If it ain't broke... et cetera, but I like them a little beefier than that.
Using that 140 number in combination with your 243 pound hook up weight makes your weak link EXACTLY 1.0 Gs. If your happy with that - fine.
If you wanted to make ME happy you could put a 196 pound weak link on the top end of your primary bridle and bring it up to 1.4 Gs. I get about 202 pounds for a double loop of Greenspot and that's more than close enough.
You're right that friction will effect some slight variation in the loading of the top and bottom ends of the bridle and also that it's gonna equalize pretty quick. I'd throw it out of the equation.
However, you can't just divide the tow line tension by two to calculate the loads on the bridle ends 'cause your shoulders are usually pretty far away from your upper mounting point and your bridle ain't infinitely long. The shorter it is the higher the loading. I use 60 degrees as the angle the bridle forms at its apex (at the tow ring) and multiply half the tow tension by 1.15 (derived trigonometrically) to figure the load the bridle end / weak link / release feels.
Example... 200 pounds on the tow line, half of that times 1.15, 115 pounds to each bridle end.
The attachment points on your shoulders are so close together that the angle formed by the secondary bridle is so acute that the load increase is negligible and I just divide the 115 by two - 57.5 pounds to each shoulder.
(Or, if you're towing one point deliberately or because your primary bridle wrap just wrapped - a hundred pounds each.)
To address the issues you raise in your Paragraph 4...
Let's call a double loop of Greenspot 200 pounds - that's fixed no matter what. Its G rating varies depending upon where it's installed and who's using it.
If YOU (243 pounds) put it at the end of your tow line, at the top end of your two point bridle, or at either/both ends of your secondary bridle it's a 0.82, 1.43, or - if your primary bridle wraps - 1.65 G weak link - respectively.
If I (320 pounds) put it at those same three places it's a 0.63, 1.09, or 1.25 G weak link.
The numbers I previously listed for single and multiple loops of Greenspot were obtained with them Double Lark's Headed onto 2000 pound Spectra hollow braid. That stuff is slippery as an eel but you do get an increase in strength from Single through Double to Triple Lark's Heads with the Fisherman's Knot isolated in their centers.
With the Fisherman's Knot exposed between the bridle eye and release I got 123 pounds last evening.
I'll bet if people whose weak links came untied were fully charged for the tow they'd be hauling ass to the nearest Boy Scout meeting.
Mark Knight,
See above and, if you want, at:
http://www.flickr.com/photos/aerotowrelease/?details=1
http://www.flickr.com/photos/aerotowrelease/sets/72057594141352219/detail
AT System Components
Break Link - Secondary - Installation
Break Link - Secondary - Starboard
down towards the end. Those photos show the Fisherman's Knot isolated in the middle of a Double Lark's Head. The weak link material is 205 leechline in that example.
Mark Johnson,
If I understand your first paragraph correctly - NO. Bigtime.
A half strength weak link at both ends of the secondary bridle is absolutely no different - with respect to capacity - from a half strength weak link on only one end.
And you don't want to do either of those 'cause now the bottom end is almost as likely to go as the top. And if the bottom end goes first and the bridle wraps you can tuck and break the glider in a couple of heartbeats if the primary release is trimmed a bit fore on the keel.
If your secondary bridle weak links (it's best to have them on both sides to maintain protection in the event of a secondary bridle wrap) are almost as strong as the one at the top end of the bridle your G rating will remain about the same if your primary bridle wraps.
Yeah, I REALLY like the idea of having a/the weak link on the end of the tow line - one less thing the pilot can screw up.
One thing I do that NOBODY else seems to that works really well... actually - two things...
I've got a thimble on the bottom end of the primary bridle so that:
1. the two bridles don't chew each other apart; and
2. you guarantee that the secondary bridle will clear the primary in the event of a primary bridle wrap.
And I connect the primary bridle to the thimble using a weak link that's just a little stronger than the primary so that if there's a primary bridle wrap you probably won't have to do anything - definitely if it follows a weak link break. See the pictures.
With respect to Jim Prahl...
I don't know him that well and, although I do admire anyone who experiments and thinks for himself... This in an example of the contagious stupidity and insanity thing I mentioned earlier.
The poor guy is making a noble effort to DEFEAT the function of the weak link while laboring under the artificially generated commandment that it can and must be ONLY a single loop of 130 pound Greenspot no matter who you're handing it to.
Again, like a parachute, you begin your flight assuming/hoping that it won't become an issue but if it does you REALLY want it to work.
The solution to the problem he is trying to solve is to use a 1.4 G weak link instead of something around half that rating.
I've posted a copy of "mousetraps" to this forum in case there's anybody here who's interested and isn't registered at skysailingtowing.
http://groups.yahoo.com/group/TUGS/message/966Mark Knight - 2008/05/01 16:11:04 UTC
I think part of the confusion here is that you (Tad) are talking over under and Mark Johnson and I are talking about pro-tow (shoulders only). You have made it abundantly clear you do not like this setup.
I am comfortable using it. I like it better because it what I know about and the simplisity. There is safety in simplisity.
The more attachment points and cables and levers put into a system add for malfunction or something to be missed.
Unforchunatly many pilots show up and are told how to do it and never question what is actually happening.
I am using a barrel on each shoulder with a green spot weaklink on each release that is tied small enough to not be able to go over and catch the ring or loop at the end of the tow rope. If I release and it does catch I have the other side to release again and it will not be going through a ring or loop. It just sets me free of everything. The tow line has a 205 leach line on the end that my bridal is passing through.
My hang weight is 220lbs.
My glider (Exxtacy) is 95 pounds
Thats 315 total.
With the weights, G's and calulations you mention. That puts me were I should be.
By the way. What weights are you getting for breaking 205 leach line?
Thanks,
Mark Knight
http://groups.yahoo.com/group/TUGS/message/967Tad Eareckson - 2008/05/02 13:34:38 UTC
Mark (Knight),
Definitions of the terms I use...
Two point - glider and pilot.
One point - pilot only (despite the fact that the tow tension is almost always split between two shoulders).
Three point - control frame apex and corners. I started towing that way in the early '80s and that's how we used to kill a lot of people until the culture started listening to Donnell Hewett.
What confusion?
In mousetraps I outline the pros and cons but in this discussion I have made no statement on my feelings with respect to two versus one.
A couple of years ago I had a pilot who wanted me to install my full two point system in his U2. I REALLY wanted to do that but I spent considerable time and effort talking him out of it in favor of one point.
You want my opinion?
If you've got a glider that tows reasonably comfortably from the shoulders only - by all means - go for it.
It's SO much simpler, cleaner, easier, cheaper... On a lot of modern gliders you hardly notice the difference. Even on my old HPAT 158 it's a lot easier than I would have thought possible - given the point on the keel at which the thing trims behind a Dragonfly.
However - on my full two point system there's ZERO opportunity to screw the setup or have a malfunction. The tow's a little more comfortable but I'm left with a lot of bridle to stow after I'm off and that job often gets consigned to the back burner while I'm clinging to survival in some anemic little thermal.
With respect to your Paragraph 4...
Yeah - That is a HUGE problem with our sport. People just accept whatever they were taught - WRONG - decades ago, never question anything, and never make any advancements.
I get the shit kicked out of me all the time for saying things like - "Ya know, folks, opting for stand up landings doesn't make hang gliding safer. It actually makes it WAY more dangerous."
With respect to your personal configuration...
You and I hook up at the same weight.
From your description it sounds like you're talking about single loops of Greenspot on your one point bridle ends?
That puts you at 0.89 Gs. And that assumes that those things aren't degrading in the course of the launch and tow - which they do.
One evening last June I badgered Victor, my engineer buddy, who hooks up at the same weight we do, to double his Greenspot. He declined and went up with a virgin single loop. A few moments later he and his Pulse were back on the ground with a broken downtube (indirect consequence). Smooth air, straight and level - POP.
That thing failed at 0.4 Gs.
The next time I saw Victor he had a double loop.
Even that double loop only gets you/him/me up to 1.27 Gs.
I hope you're running that secondary bridle through some sort of ring or carabiner on the end of the tow line - rather than a loop of line - for lotsa reasons.
If you look at my pictures:
http://www.flickr.com/photos/aerotowrelease/?details=1
http://www.flickr.com/photos/aerotowrelease/sets/72057594141352219/detail
AT System Components
Secondary Bridle Assembly
you will see what a one point system SHOULD look like. You don't have to take your hand off the steering wheel to deal with a situation gone south, the barrel release far exceeds the performance requirements (rather than falling far short of them like the ones you're using), and it is physically impossible for a hangup to occur following the actuation of either release or the weak link failure.
The weak link never degrades and never needs replacing.
You should be using a 13 stitch, black/yellow, 455 pound, 1.44 G bridle link.
I got a single loop of 205 leechline Double Lark's Headed onto a 2000 pound Spectra bridle eye breaking at 262 pounds.
Tad Eareckson - 2008/05/04 23:20:26 UTCMark Knight - 2008/04/27 15:08:22 UTC
I would rather have a ocasional break and something that breaks easily when things go bad.Everybody see the conflict there?Gregg Ludwig - 2008/04/21 22:46:04 UTC
In Texas a weak link failure can be a real pain because of the hassle and expense of another tow.
The rule is 0.8 to 2.0 Gs. The middle of that safety range is 1.4 Gs. Everybody OK with that? Anybody still think that a single loop of 130 pound Greenspot is perfect for all solo gliders?
I just put up the latest mousetraps edition which leaves no doubt as to my feelings and recommendations about one point towing and includes a new column in the G Ratings tables which gives the ideal hookup weight for all shear link increments.
If you've gotten as far as accepting 1.4 Gs as the number for which we should be shooting then the sacred 140 pound single loop is optimized for the following hookup weights depending upon their tow modes:
174 - two point
200 - one point
That is certifiably insane.
The hookup weights that do 1.4 with a 200 pound double loop are:
248
286
That's a lot closer to what those of us who aren't small children and anorexic supermodels wanna be.
-
llwest@comcast.net
- Posts: 18
- Joined: 2011/01/26 14:30:47 UTC
Re: Broken arm Saturday for discussion
http://www.youtube.com/watch?v=VYe3YmdIQTM
I talked to Bryan today and he wants to fly again after the three breaks in his humerus heal. We shall see.....I couldn't tell yet if all the lessons have been learned that I hope were learned, but he did say he appreciated the things I said to him that day and wishes he had listened more.
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Tad Eareckson - 2022/06/10 12:15:00 UTC
Video's out reach, see stills:
http://www.kitestrings.org/post11958.html#p11958
I talked to Bryan today and he wants to fly again after the three breaks in his humerus heal. We shall see.....I couldn't tell yet if all the lessons have been learned that I hope were learned, but he did say he appreciated the things I said to him that day and wishes he had listened more.
---
Tad Eareckson - 2022/06/10 12:15:00 UTC
Video's out reach, see stills:
http://www.kitestrings.org/post11958.html#p11958
-
Tad Eareckson
- Posts: 9161
- Joined: 2010/11/25 03:48:55 UTC
Re: Broken arm Saturday for discussion
That's one of the greatest hang gliding videos I've ever seen. It so beautifully illustrates everything all of these iconic hang gliding figures - Donnell, Malcolm, Matt, Dennis, Bryden, Davis, Rooney - have been trying to make us weekend warrior losers understand about Hewett Links all along.
- It totally prevented the glider from being overstressed. I'd be amazed if it was up close to fifteen percent of its capacity. Talk about SAFETY MARGIN!
- It prevented the glider from pitching up too much. Bryan's climbing a bit too hard and the Hewett Link blows - just like it's supposed to. And even though he continues to try to push the nose up afterwards it starts dropping back to something pretty reasonable after no more than two seconds - then REALLY starts recovering.
- It broke before he could get into too much trouble. He's absolutely fine when it blows - and for a good four seconds afterwards.
- It *saved* his ass. He still piled into the earth despite it helping him. But it HAD to help - because of his lack of towing ability. God only knows what might have happened if he had been allowed to stay on a few seconds longer.
-- He could've decided to nose up even more, gotten higher, and have stalled even more severely when the weak link decided it had had enough.
-- It's a pretty good bet he'd have had a severe lockout - given a little more time.
-- And if he HAD - by some miracle - managed to pile in with the Hewett Link still intact and broken four ribs and his larynx in addition to his arm, NO WAY he'd have been dragged.
http://groups.yahoo.com/group/skysailingtowing/message/4606
Weaklinks and aerotowing (ONLY)
Anyway...
If he does a lot of foot launch towing and keeps doing idiot hang checks so he can assume he's hooked when he's connected to the towline the probability of him launching unhooked on the runway is really good - and not bad when he goes to the mountains.
- Even if he's using a sane weak link - three or four times as strong as the crap he was using - he needs to launch as if he's on a Hewett Link. Enough speed reserve to handle the event that there's no excuse for having. We all know that and - hopefully - Bryan also now knows what he should've well before he got his rating.
- We can very clearly see that the bridle is routed over the basetube so the pitch is all pilot (and the Hewett Link blows within a second of bridle contact with the basetube so the routing isn't any kind of detectable factor in this tow).
- As you've noted, he needs to get his hands on the basetube IMMEDIATELY 'cause he:
-- gets a lot better speed and control authority
-- is a lot less likely to break his right arm into four pieces.
- A BIG factor in his getting his right arm broken into four pieces was that he's been extremely hardwired to foot land.
-- He leaves his hands high on the downtubes after launch to be prepared for foot landing.
-- When the Hewett Link blew he REALLY needed to go to the basetube to stuff it and get some flying speed.
-- Instead he does the precise opposite. He shifts his hands WAY the hell up towards the apex for an insane degree of flare authority - which he can't use anyway 'cause he's already majorly stalled.
- And I guess nobody has to tell him that he'd have been OK if - since because he didn't react properly to the Hewett Link blow immediately (or at any time thereafter) he stayed stalled all the way down - he had just let go of the control frame and gone into crash mode.
- Does that mean all his new gear is no longer for sale?
402 - 1.5 G weak link
450 - Tost No. 8 - 1.7 Gs
The crap he was using blew at about 130.
P.S. Hey Zack, notice that his legs are out of the pod but it would've made no difference whatsoever if he had been zipped up when he came down?
- It totally prevented the glider from being overstressed. I'd be amazed if it was up close to fifteen percent of its capacity. Talk about SAFETY MARGIN!
- It prevented the glider from pitching up too much. Bryan's climbing a bit too hard and the Hewett Link blows - just like it's supposed to. And even though he continues to try to push the nose up afterwards it starts dropping back to something pretty reasonable after no more than two seconds - then REALLY starts recovering.
- It broke before he could get into too much trouble. He's absolutely fine when it blows - and for a good four seconds afterwards.
- It *saved* his ass. He still piled into the earth despite it helping him. But it HAD to help - because of his lack of towing ability. God only knows what might have happened if he had been allowed to stay on a few seconds longer.
-- He could've decided to nose up even more, gotten higher, and have stalled even more severely when the weak link decided it had had enough.
-- It's a pretty good bet he'd have had a severe lockout - given a little more time.
-- And if he HAD - by some miracle - managed to pile in with the Hewett Link still intact and broken four ribs and his larynx in addition to his arm, NO WAY he'd have been dragged.
http://groups.yahoo.com/group/skysailingtowing/message/4606
Weaklinks and aerotowing (ONLY)
I think Bryan was pretty close to ol' Dr. Howell's half G figure for an inexperienced pilot - probably even a little extra safety margin.Davis Straub - 2005/02/09 06:13:39 UTC
Weaklinks need to be strong enough to not break in circumstances where they would put the pilot in trouble, but weak enough to break to help get the pilot out of worse trouble.
How strong should aerotow weaklinks be?
The lowest figure I've seen is that they should break at 85 kg (187 pounds) of tension. The range discussed at the Worlds was 85-115 kg (187 lbs to 253 lbs).
Donnell Howell mentions (using hookin weight of 100 kg and glider weight of 36 kg):
0.5 G - inexperienced pilot: 68 kg (150 lbs)
1.0 G - experienced pilot: 136 kg (300 lbs)
2.0 G - very experienced aerobatic pilot: 270 kg (600 lbs)
Anyway...
- And, as is also obvious from the video, skipped doing, and has undoubtedly never even heard of, a hook-in check - despite the fact that he had just gotten his surface tow rating from the guy who was the first to reach the Kunio Yoshimura's impact zone below launch three and a half years ago.He rushed to the end of the line while Mel was still in the air, rushed to hook in, did a hang check, and hook up and was calling go.go.go while I was still trying to figure out how to do video on my phone.
If he does a lot of foot launch towing and keeps doing idiot hang checks so he can assume he's hooked when he's connected to the towline the probability of him launching unhooked on the runway is really good - and not bad when he goes to the mountains.
- Even if he's using a sane weak link - three or four times as strong as the crap he was using - he needs to launch as if he's on a Hewett Link. Enough speed reserve to handle the event that there's no excuse for having. We all know that and - hopefully - Bryan also now knows what he should've well before he got his rating.
- We can very clearly see that the bridle is routed over the basetube so the pitch is all pilot (and the Hewett Link blows within a second of bridle contact with the basetube so the routing isn't any kind of detectable factor in this tow).
- As you've noted, he needs to get his hands on the basetube IMMEDIATELY 'cause he:
-- gets a lot better speed and control authority
-- is a lot less likely to break his right arm into four pieces.
- A BIG factor in his getting his right arm broken into four pieces was that he's been extremely hardwired to foot land.
-- He leaves his hands high on the downtubes after launch to be prepared for foot landing.
-- When the Hewett Link blew he REALLY needed to go to the basetube to stuff it and get some flying speed.
-- Instead he does the precise opposite. He shifts his hands WAY the hell up towards the apex for an insane degree of flare authority - which he can't use anyway 'cause he's already majorly stalled.
- And I guess nobody has to tell him that he'd have been OK if - since because he didn't react properly to the Hewett Link blow immediately (or at any time thereafter) he stayed stalled all the way down - he had just let go of the control frame and gone into crash mode.
- Which, seeing as how he's a surgeon and oughta know what he's talking about, is a pretty good indication that the three breaks in his humerus WILL heal. Good to hear that.I talked to Bryan today and he wants to fly again after the three breaks in his humerus heal.
- Does that mean all his new gear is no longer for sale?
Which is a real good indication that they HAVEN'T been.I couldn't tell yet if all the lessons have been learned...
That's something anyway....but he did say he appreciated the things I said to him that day and wishes he had listened more.
268 - max flying weight...Falcon 3 170...
402 - 1.5 G weak link
450 - Tost No. 8 - 1.7 Gs
The crap he was using blew at about 130.
P.S. Hey Zack, notice that his legs are out of the pod but it would've made no difference whatsoever if he had been zipped up when he came down?
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Tad Eareckson
- Posts: 9161
- Joined: 2010/11/25 03:48:55 UTC
Re: Broken arm Saturday for discussion
Further thoughts...
These BASTARDS are a big part of the problem.
http://www.kitestrings.org/post398.html#p398
but a few more words...
Go to USHGA and get a list of AT Administrators. Here are a few I know something about in the order in which they appeared:
Paris Williams
Bart Weghorst
David Glover
Tracy Tillman
Adam Elchin
Felipe Amunategui
Steve Wendt
Paul Tjaden
G.W. Meadows
Mitchell Shipley
Matthew Taber
Paul Voight
Useless
Clueless
Waste of Space
Asshole
Moron
Evil Motherfucker
All of them fit into at least one category and some qualify for four. The only reason nobody makes it to five is 'cause one really can't be an Evil Motherfucker and hold any of the other titles.
And none of the people I didn't harvest is doing shit in the way of addressing any real issues so they can all be assumed to be useless AT BEST.
So the proud new owner of the Falcon 3 170 is already pretty screwed.
And the qualified aerotow instructor assholes at Quest - who are TOTALLY CLUELESS about the strength - can't even get the length right.
So note that Wills Wing is ONLY voicing concern about about the weak link being an impediment to getting OFF tow and the presumption is that there's absolutely no danger presented by a weak link which can prevent one from staying ON.
Anybody with half a brain or better knows that all Industry Standard aerotow releases and bridles are unreliable crap. Failures are so common that nobody even thinks them worth mentioning.
But the reason that the Industry Standard equipment remains the shit that it is is because the Flight Park Mafia scumbags like Matt and Tracy understand that it rarely matters. The establishment assholes - flight park operators, tandem drivers, instructors, competitors - all know that low level emergencies in which one's life is dependent on solid equipment are extremely rare and virtually entirely avoidable. It doesn't take much in the way of skill or judgment to stay out of low level critical situations - and they've got it.
http://groups.yahoo.com/group/TUGS/message/1149
aerotow instruction was Re: Tug Rates
They know that if anybody's gonna get killed because of crappy equipment it's gonna be a Two or a new Three, Twos and new Threes are a dime a dozen, they'll get to write the fatality report, and they can always write it off as pilot error: ...failed to effect timely control input, made no attempt to release...
They know that the real danger is blowing a weak link on takeoff so they use weak links that don't blow or - at Lookout - no weak link at all. Then they train the tandem student to handle a weak link blow by pulling a lever at a thousand feet, sign him off, and put him up solo on a weak link that blows at ten feet every other tow so they can sell him more downtubes and force him back up on tandem rides for remedial training.
http://www.aviationbanter.com/archive/index.php/t-40965.html
Are Weak Links really Necessary for Aero Tow?
Those bastards have been pushing towing since the mid Eighties. Their big dealers are aerotow operations, they're heavily pushing scooter tow as an entry point for fresh customers, they're in bed with Steve Wendt, and all of the hot competition gliders they're selling are getting aerotow launched. And they're talking about always using an "APPROPRIATE WEAK LINK"? Without ever a mention of Gs or even pounds?
If the fuckin' Wills Wing Falcon 3 manual had specified the weak link rating the way the fuckin' Nimbus 2C manual does it would've listed a 450 pound Tost No. 8.
And then when Bryan had started running to the launch line with the idiot goddam Davis Link that was about to break his arm Larry would've been able to say, "What's it say in your owner's manual?"
And if that still didn't stop him then at least when Larry talked to him this past Sunday he'd have been able to say, "Understand now why it says that in your owner's manual?"
I watched a friend break his arm Saturday and take out the downtubes of his Falcon 3 170...
I don't really like doing this 'cause, as I've often said, I always liked Rob, Mike has been very helpful to me over the years, and Steve has done some great things with gliders... But in this game you can't afford to just look at what's right with equipment, procedures, and people - if you do your gonna get a lot of really ugly crashes. Ya gotta look at what's WRONG and get brutal.Zack C - 2010/12/13 04:58:15 UTC
I had a very different mindset too back then and trusted the people that made my equipment. Since then I've realized (largely due to this discussion) that while I can certainly consider the advice of others, I can't trust anyone in this sport but myself (and maybe the people at Wills Wing).
These BASTARDS are a big part of the problem.
I've already done a hatchet job on that article at:Aerotow Release Attachment Points for Wills Wing Gliders
by Rob Kells
http://www.kitestrings.org/post398.html#p398
but a few more words...
As far as I can tell - there ARE NO qualified aerotow instructors. They're essentially a bunch of bozos who are really good at saying and doing what all the other bozos are saying and doing and have been for decades.Please do not attempt to aerotow any glider without first receiving instruction from a qualified aerotow instructor.
Go to USHGA and get a list of AT Administrators. Here are a few I know something about in the order in which they appeared:
Paris Williams
Bart Weghorst
David Glover
Tracy Tillman
Adam Elchin
Felipe Amunategui
Steve Wendt
Paul Tjaden
G.W. Meadows
Mitchell Shipley
Matthew Taber
Paul Voight
Useless
Clueless
Waste of Space
Asshole
Moron
Evil Motherfucker
All of them fit into at least one category and some qualify for four. The only reason nobody makes it to five is 'cause one really can't be an Evil Motherfucker and hold any of the other titles.
And none of the people I didn't harvest is doing shit in the way of addressing any real issues so they can all be assumed to be useless AT BEST.
So the proud new owner of the Falcon 3 170 is already pretty screwed.
So all an APPROPRIATE weak link is is something with a finished LENGTH of 1.5 inches inches. We're not the least bit concerned about the STRENGTH - oddly enough.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.
And the qualified aerotow instructor assholes at Quest - who are TOTALLY CLUELESS about the strength - can't even get the length right.
So note that Wills Wing is ONLY voicing concern about about the weak link being an impediment to getting OFF tow and the presumption is that there's absolutely no danger presented by a weak link which can prevent one from staying ON.
Anybody with half a brain or better knows that all Industry Standard aerotow releases and bridles are unreliable crap. Failures are so common that nobody even thinks them worth mentioning.
But the reason that the Industry Standard equipment remains the shit that it is is because the Flight Park Mafia scumbags like Matt and Tracy understand that it rarely matters. The establishment assholes - flight park operators, tandem drivers, instructors, competitors - all know that low level emergencies in which one's life is dependent on solid equipment are extremely rare and virtually entirely avoidable. It doesn't take much in the way of skill or judgment to stay out of low level critical situations - and they've got it.
http://groups.yahoo.com/group/TUGS/message/1149
aerotow instruction was Re: Tug Rates
Nothing's ever gonna happen to them at launch and when they get up a couple thousand feet there's no real problem letting go of the basetube with a hand or two to pry something open, go to a "backup", or roll the glider harder into a lockout to actuate the Ryan Voight Instant Hands Free Greenspot Release.Tracy Tillman - 2011/02/10 20:08:32 UTC
Anybody who is truly a good pilot, in any form of aviation, knows that the knowledge, skills, and judgement you have in your head, learned from thorough instruction from a good instructor with a good curriculum, are the best pieces of equipment you can fly with. Good equipment is important, the best equipment is a well-trained brain.
They know that if anybody's gonna get killed because of crappy equipment it's gonna be a Two or a new Three, Twos and new Threes are a dime a dozen, they'll get to write the fatality report, and they can always write it off as pilot error: ...failed to effect timely control input, made no attempt to release...
They know that the real danger is blowing a weak link on takeoff so they use weak links that don't blow or - at Lookout - no weak link at all. Then they train the tandem student to handle a weak link blow by pulling a lever at a thousand feet, sign him off, and put him up solo on a weak link that blows at ten feet every other tow so they can sell him more downtubes and force him back up on tandem rides for remedial training.
http://www.aviationbanter.com/archive/index.php/t-40965.html
Are Weak Links really Necessary for Aero Tow?
Bill Daniels - 2006/09/18 14:30
I would like to add, however, that at least my reading of accident reports suggest that a fatal glider accident is more likely when the towline fails prematurely. For that reason, I like to stay near the stronger end of the FAR eighty to two hundred percent range.
Actually, reading the Pilot's Operating Handbook for several German gliders, I note the weak link for aerotow is specified as an exact figure. For example, the weak link for both aero tow and winch for my Nimbus 2C is specified as 600 KG (1323 Lbs) or a blue Tost weak link. The tolerance is plus or minus ten percent. The US Airworthiness Certificate specifies that the Nimbus 2C is to be flown as specified in the POH. Considering the possible flying weights, this ranges between 95 to 160 percent which is a narrower range than specified in the FAR's.
Makes me wonder if we should be using Tost weak links instead of old bits of rope.
Sorry, that's despicable bullshit. You think the guys who pushed the technology from SSTs and Ravens to the U2s and T2s are too fucking stupid to know that that's a totally meaningless statement? Too fucking stupid to know that there's an appropriate weak link for a specific glider the way there is in sailplaning? They're part of the conspiracy that'll maintain to their deaths that the lighter the weak link the safer the tow.Always use an appropriate weak link...
Those bastards have been pushing towing since the mid Eighties. Their big dealers are aerotow operations, they're heavily pushing scooter tow as an entry point for fresh customers, they're in bed with Steve Wendt, and all of the hot competition gliders they're selling are getting aerotow launched. And they're talking about always using an "APPROPRIATE WEAK LINK"? Without ever a mention of Gs or even pounds?
If the fuckin' Wills Wing Falcon 3 manual had specified the weak link rating the way the fuckin' Nimbus 2C manual does it would've listed a 450 pound Tost No. 8.
And then when Bryan had started running to the launch line with the idiot goddam Davis Link that was about to break his arm Larry would've been able to say, "What's it say in your owner's manual?"
And if that still didn't stop him then at least when Larry talked to him this past Sunday he'd have been able to say, "Understand now why it says that in your owner's manual?"
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Steve Davy
- Posts: 1338
- Joined: 2011/07/18 10:37:38 UTC
Re: Broken arm Saturday for discussion
Any news on how Bryan is doing?
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llwest@comcast.net
- Posts: 18
- Joined: 2011/01/26 14:30:47 UTC
Re: Broken arm Saturday for discussion
I haven't heard from him in a couple of months, but he was healing great then and hoped to be back in the air before fall of this year.