How big was the Texas "contingent"? You DO know the formula calculating group intelligence? Take the lowest individual IQ and divide it by the number of individuals in the group? Then if they're hang glider people divide that result by three. (Must resist urge to make Texas joke.)
...showed at Lookout's...
Lockout Mountain Flight Park. A real bastion of hang gliding competence and integrity.
...party...
Free beer, I assume?
...last night--including school/tow operators and a pilot familiar with the accident victim.
- None of whom:
-- have any actual names or stated ratings or credentials
-- could be bothered to post a single punctuation mark for the record on this one
- Lenny and Patricia were tow operators. Rigged and developed a solid sounding payout system, got through the critical phase of the launch a hundred times better than the only non Donnell report we have from Kingsville.
- Was one of them Donnell?
- Why not?
- How many of them tow with Infallible Weak Links, Skyting Bridles, Linknives?
- Oh! A PILOT with zero stated credentials other than being from somewhere in Texas was FAMILIAR WITH the ACCIDENT victim - but never having actually seen him fly and never having actually discussed any relevant flying issues with him. So obviously he knew that Lemmy was a fundamental asshole accident-waiting-to happen with total shit judgment and really iffy if any actual flying aptitude - which contradicts everything his decades experience, highly acclaimed, u$hPa certified instructor reported about him.
- So now we know Donnell's totally full o' shit and has lied in his assessment of his 38 flight and ground school student.
- Pity A PILOT never gave him any useful guidance or advised him to pursue another hobby.
They all believe the cause was error in judgment...
- Really hard to argue with that one.
- On what information ALL OF THEM basing their BELIEF that we haven't seen and discussed here?
...on the the part of the accident pilot.
- He has a name - motherfucker. At least he used to before you u$hPa douchebags finished dealing with him.
- Funny we didn't hear anything one way or another about Donnell's influence on the situation.
- Speaking of errors in judgment... Really great job proofreading your 51 word post.
This is why I got banned so quickly everywhere. I know how to cut through crap like this like a hot knife through butter. And everyone with any position of influence in the sport is totally full of it.
What info are you referring to that they apparently do not know of?
Two plus two equals four maybe?
Rob Clarkson - 2010/10/31 21:54:20 UTC
Besides lack of info what ignorant FoS comments are you refering to? Perhaps I need to explain myself better.
Maybe try writing at a grade school competency level.
Wescanfly - 2010/11/01 00:54:20 UTC
When, Mr. Hewett posted, his primary release was a make-shift "Linknife" Does this imply the pilot fabricated a release or that he was using a genuine "Linknife" and that Mr. Hewett considers it sub-par.
The former - idiot.
I have used a Linknife for years and it is anything but make-shift
What kind of rope do you use to attach it to the pilot's harness on the left side, similar to the way Lemmy had been trained?
John Haig Thompson - 2010/11/01 11:18:32 UTC
From page3 of this thread, it does sound a home made "Linknife"
I hate those things. They only work well on the preflight tests. In a lockout you need to pull on the rope three or four times. With the real Linknife the greater the pressure on the weak link the BETTER it works.
Revised Accident Report 10-24-10
Only after the accident did I learn that his primary release was a make-shift "Linknife" constructed from a thin plastic tube with two single-edged razor blades inserted parallel to one another inside. It was activated by a rope attached to the pilot's harness on the left side...
Parallel razor blades... What WAS he thinking?
Steve Seibel - 2010/11/01 17:28:43 UTC
toward a higher standard of discourse
Get your ass outta there for starters.
May I suggest that we review the whole thread more carefully before thickening the plot with more questions--
Maybe somebody should actually read Donnell's final 2010/10/26 05:49:12 UTC report. Or were the half dozen rather hefty paragraphs way too much for y'all's fifteen second attention spans? (TLDR...)
I think the earlier post by Peter B. answers the question you, Wes, asked.
The real Peter B. - inventor of the real Linknife. (That he's been unable to safely actuate in two of the two emergency tow situations he's experienced.
Christian Williams - 2010/11/01 18:14:11 UTC
Personally, I don't think there is much to learn from this particular accident.
I agree. If there were anything to actually learn from this particular accident we wouldn't be referring to it as an accident. Besides... When has hang gliding ever actually learned enough from a fatal impact to be able to prevent another one just like it three or four months later?
Don't worry. Just four more posts to go then we can all go back to exactly the same shit we were doing before and expecting much better results.
Christian Williams - 2010/11/01 21:30:43 UTC
No, because there are so many oddities to the particular situation that it doesn't say much about towing, instruction, safety, appropriate glider size, or the responsibility of instructors.
In stark contrast to the:
- Zack Marzec
- Scott Howard
- Kelly Harrison / Arys Moorhead
- Tomas Banevicius
- Jeff Bohl
- Nancy Tachibana
we're gonna be seeing soon in the coming few years.
Most accidents I can learn from...
Anybody who can learn anything FROM - rather than ABOUT - any hang gliding "accident" is a total moron. We're not inventing new ways to crash that we didn't have plenty of examples of in the first decade of the sport.
...but this accident chain has too many kinks.
No. It's got to many distortions, misdirections, omissions, contradictions. And that's just about all you really need to know and/or learn about.
Doug Doerfler - 2010/11/02 07:37:04 UTC
We have the results of a 10 minute airtime pilot building his own tow rig and using it for the first time with a driver with zero experience.
Go fuck yourself. We have no indication that:
- anything they were using wasn't at least the quality of the crap upon which he was training
- there were any equipment failures
- anybody did anything contrary to or south of Donnell's training
- Patricia hadn't acted as a driver and/or back-ender at Donnell's operation
I'd say there is alot to learn in that
I don't really give much of a flying fuck about anything you have to say.
I towed with the boys and girls in Canada a few seasons, there was alot of time, effort, experience and pride that went into their tow rigs...
And I'm sure that Lemmy's was total crap. Although he took the initiative to build his own rig and fabricate his own Linknife it's totally absurd to assume that anything would've lasted more than half a tow - if they were lucky.
...and a significant amount of time and effort into training a new driver.
Yeah. Maybe you could write up a manual on all the shit a payout pickup has to know and do. That's something we don't seem to have in any of the existing literature.
Maybe include something about somebody giving the glider a quick glance...
And I'll tell ya sumpin'... Both those motherfuckers had done real top notch jobs on their rigs.
What we can learn...we all have screwed up once in a while, but you start piling on the bad decisions and the chances of it all working out go in the toilet real quick
One hundred percent of that shit is on Donnell. That's how come as far as the sport is concerned he's one hundred percent as extinct as Lemmy.
But the #1 root cause...this 10 minute airtime pilot had no idea how many bad decisions he was stacking up
Really just one bad decision - trusting Donnell and his training.
Brian McMahon - 2010/11/02 16:15:20 UTC
Literally the only thing I can think of is 'don't do what he tried to do'.
Learn to fly hang gliders. Got it. Problem solved. The whole sport and the pool of potential pilots we have in society at large is with you. And the fatality rate has been pretty low the last few years 'cause the sport itself is in a death spiral.
Christian is right, this situation is such an abberation that there is little purpose analyzing all of the details.
Plus none of you motherfuckers have ten percent of the IQs necessary to scratch the surface analyzing any of this.
If somebody was walking on the roof-edge of a tall building and fell off to his death, would you analyze his walking technique, his shoes, the weather conditions, the surface of the roof he was walking on, whether he had more weight in one pocket than another; and then try to find a rational explanation of what went wrong?
Yes I would 'Cause this is a hang gliding forum so my assumption would be that he was wearing a hang glider and that's one way we get ourselves airborne. Move close to the edge of a tall building, ramp, platform, cliff and fall off.
It's pointless, he shouldn't have been there in the first place.
He wasn't there in the first place. He was there in the 39th place. And if Donnell's program had had anything in the way of validity he would've either been OK on his own rig or going back up to Kingsville for some tows up into thermalling conditions.
Wescanfly - 2010/11/05 00:18:26 UTC
Steve Seibel - 2010/11/01 17:28:43 UTC
...
Point well taken. Wes
Steve Seibel can go fuck himself. That asshole came reasonably close to killing himself 'cause he missed his leg loops and can't be bothered to do hook-in checks....
...and won't even acknowledge the effort from Helen McKerral to help him get his stupid shit together.
End of thread and dissections.
This one's huge in the world history hang glider towing and in the world history hang gliding in general. Although the credit for taking the lower attachment off of the basetube and onto the pilot should've gone to Brian Pattenden who was:
- a year ahead of Donnell
- theory-only and never towed in any configuration
- non US
it was Donnell who got stuff out in print globally and fueled the transition everywhere outside of East Anglia despite being pretty much totally clueless and worse on the aeronautical theory from Day One at some point in 1980, probably after my 1980/04/02 entry into the sport, on through to his last detectable pulse in the sport - 2010/10/24. (Still physically alive and kicking though - still listed as faculty in the physics department at Texas A&M Kingsville. (DOB - 1930/07/20.)))
He's gotten a young lawyer killed and there's a civil war going on at u$hPa's most prominent official unofficial publicly accessible forum. Lemmy had a hang gliding qualified wife and (nonqualified) kids and is gonna have lawyer close friends. This puts u$hPa and other US commercial hang gliding interests in a real precarious situation and they want this incident, situation, discussion and Donnell to quietly and permanently disappear. And, save for here and now on Kite Strings, it totally does.
I also need to do another archive of another very relevant discussion - which I won't identify just yet 'cause I don't want any of the posts to have any accidents. The history of this sport is critically important and the motherfuckers who control and exploit the sport really don't want most of it known.
Nice concise cleaned up archive of the 68 posts of the Davis Show discussion of the 2010/10/13 Hewett product Lemuel Lopez lockout crash fatality which will end Donnell's association with the sport of hang gliding and get him and his Skyting Theory expunged from the mainstream history books. A few alterations for formatting, typo, spelling level issues but no omissions or distortions of intent. And feel free to check against the original currently publicly available source.
Police are investigating the death of an Hidalgo County lawyer killed while hang gliding in Edinburg. Lemuel Lopez died along the stretch of Constitution Street and Highway 281 Wednesday evening. Police say he was in a hang glider being pulled by a pick-up truck.
Lemuel had been learning from Donnell Hewitt and was likely flying a Wills Wing Falcon.
Donnell Hewett writes:
Lemuel Lopez was a wonderful person with an adventurous spirit who took six hang gliding lessons from me and logged some thirty flights totaling about ten minutes in nine months. He was progressing well with consistently good take-offs, climb outs, straight flights, releases, and landings. He was also progressing well in ground school and was well aware of the risks of trying to tow on his own. Therefore, I was shocked to learn that he had built himself a towing system and was killed while using it to tow in Edinburg (some 100 miles away from me in Kingsville).
I have filed an accident report to USHPA and am continuing to investigate what happened. So far I have learned that he was towing with his own unproven towing system accompanied only by an inexperienced driver. He foot-launched successfully and climbed to an altitude of about 100 ft on a 250 ft towline. When the driver could no longer see the pilot in the rear view mirror, the driver stopped and may even have backed up somewhat before getting out of the pickup to watch the flight. The pilot apparently tried to release without success by cutting his weak link with a pocket knife. He continued to fly straight ahead with the towline draped over the control bar still attached to the pickup. When the towline tightened, the glider nosed down and the pilot crashed head first into the ground. He was killed on impact.
As stated previously, I am continuing to investigate the incident to confirm the above report because I have had no opportunity to interview the only eye witness, namely, the driver who obviously has been distraught over the tragedy.
There is a lot to learn from this accident (and a lot more to find out). The only problem is that we've already learned it many times.
*
Davis Straub - 2010/10/20 02:27:23 UTC
From: Lionel Hewett
Sent: Tuesday, October 19, 2010 2:02 PM
To: Davis Straub
Subject: RE: Truck towing accident?
Davis,
No, they did not simply hook the rope to the pickup. They were using a home built payout winch that I have never seen. And, I suspect that they tested its tension setting by pulling some line out immediately before foot-launching, because that is the procedure they had been practicing when using my equipment. But when one fails to release and overflies the payout winch, the normal towing tension is enough to force the glider into the ground, especially when the towline is routed over the control bar. I am confident that they were also using a weak link (because that was what they always trained on), but again a towline force sufficient to cause a tuck is not sufficient to break a weak link.
Clearly, Lemuel thought he understood the critical components of my towing system and tried to duplicate what he thought was important. He also thought he was competent to launch, climb out, release, and land because he had done so consistently numerous times. He simply forgot or ignored the dangers of (1) towing without an instructor present, (2) using an inexperienced crew, (3) not using an observer with the winch, (4) not using a reliable release at the pilot end of the towline, (5) using a pocket knife rather than a hook knife as an emergency pilot release, (6) not having an emergency release at the winch end of the towline, (7) failing to release from tow, (8) dragging a slack towline, (9) overflying the tow vehicle, and (10) flying too high on a short towline. These are mistakes that cost him his life. They are also mistakes well known to the towing community and must continue to be emphasized in every tow-training program. My mistake was failing to emphasize the danger of these mistakes sufficiently to prevent him from making them.
Donnell
*
Gerry Grossnegger - 2010/10/20 03:47:23 UTC
What kind of release was at the top end of the rope?
What kind of rope was it (twisted or braided)?
*
Marc Fink - 2010/10/20 07:36:24 UTC
Students are often motivated to save money and hasten progress (as they see it) by getting their own gear so they can fly on their own early in their development.
*
Dallas Willis - 2010/10/20 15:11:04 UTC
Donnell Hewett - 2010/10/19 13:21:59 UTC
six hang gliding lessons ... totaling about ten minutes [airtime] in nine months.
I can hardly believe someone with the brains to be a lawyer did this.
*
Jim Rooney - 2010/10/20 18:44:20 UTC
Thanks for the update from Lionel.
Spot on Dallas.
*
Rob Clarkson - 2010/10/20 23:44:40 UTC
I don't really find this that surprising. Just the nature of learning to hang glide has a lot of risk and we work very hard to keep our students within their limits and safe. Just about every student I've ever seen stick with it pushes against those boundarys we set to try and keep them safe. Always always always it's move down the hill your too high, no your not ready to move up any further, it's too windy we can't fly today. Just about never do they except what they are told with out question. At least not the ones who will stick with it.
Some manage to listen and learn enough to stay safe, some push harder and I've seen students get hurt bad early on when they refused to listen and will quite and never come back. Some get lucky and don't get hurt but learn their lesson the hard and expenisive way.
This is very sad and tragic news but really not surprising. Just makes me think he had the love and desire to really stick too it. I would say he really wasn't any different than the rest of us that have the sport in our blood.
One thing I'm unclear of, he was using a pay out winch with only 250' of line? That seem very odd to me.
*
Davis Straub - 2010/10/21 15:47:05 UTC
That is very unclear. I think (from emails from Donnell) that there was more than 250' on the reel (not clear how much a real payout winch it was) but that only 250' were out when the driver stopped the truck.
*
Davis Straub - 2010/10/21 16:31:43 UTC
From: Lionel Hewett
Sent: Wednesday, October 20, 2010 6:57 AM
To: Davis Straub
Subject: RE: Truck towing accident?
Davis,
Yes, that is my understanding. I do not know if that was the total length of the rope including what was wound up on the reel or the length of the rope strung out while towing. His brother, who heard from the only eye witness, told me that there was towline still on the reel after the accident. Therefore, I suspect that there was about 250 ft of line between the pickup and the pilot.
Donnell
*
Gregg Ludwig - 2010/10/24 13:16:14 UTC
Low'n'slow training with proper equipment is a great way to introduce HG to new students and get them hooked on flying. A training program, however, that only provides 10 minutes of airtime with 6 lessons over a 9 month period is seriously lacking...it is no wonder this student tried to speed up his progress on his own. A some point early on, students should be referred to professional instructors who offer tandem training for the fastest, safest and easiest way to learn.
*
Bille Floyd - 2010/10/24 14:48:32 UTC
Hope nobody thinks that I'm overstepping boundaries here,with this statement, But i'm going to say it anyway...
"There simply --IS NO BETTER WAY-- it introduce a new-be to the fundamentals of Hang Gliding, than tandem time with an instructor" ( . )
When tandem,the student doesn't have that,( I'm all alone here - what happens if I forget ), feeling and the learning curve increases exponentially.
Not even a radio on the helmet will give a person the same security as another human, ready to take-over, if things go Bad !!
*
Marc Fink - 2010/10/24 15:12:20 UTC
I'd be careful about judgments that qualify one training method as being better over another. I would argue that training with the "low and slow" scooter as being more effective and safer in initial training than any other--but tandems certainly have their place--as do foot-launch training hills and other towing methods--as a training methods.
*
Davis Straub - 2010/10/24 15:27:32 UTC
This is a much better way - low and slow "scooter" tow training. It is by far the "best" way to get introduced to hang gliding. It has been shown rather conclusively by the analysis of the results at Lookout Mountain that getting the student to "fly" first on their own is what gives them that "pivotal" experience.
Tandem instruction suffers from numerous defects which I don't need to go into now.
*
Bille Floyd - 2010/10/24 16:08:58 UTC
Sometimes I forget about stepping on toes,
I Don't have any !!
Davis--"FLY" first...
Rick-- "Low and slow"...
Guess we Kinda Need all of them to build a rounded pilot !
*
Sam Kellner - 2010/10/24 16:14:52 UTC
Let's not get in an argument about which method is best...bla bla... subject: accident in S Tx.
Gregg said at some point AFTER the low and slow instruction...
After the low and slow, what we have available in Lemuel's area is tandem instruction, eventhough it would be a considerable drive from Edinburg, it would have most likely saved his life.
Gregg makes the "real" point, that a student shouldn't have to wait 9mo. to get 10min of airtime. Accident waiting (ornot) to happen for the second time this year in Reg11.
Sam,
SW Texas Hang Gliders
*
Marc Fink - 2010/10/24 22:17:49 UTC
I don't know if you guys really mean it--but asserting that the student "shouldn't have to wait" sounds almost like implying a deficiency on the instructor/school. Who knows what the reasons are for the lesson frequency/progression.
My take is the real failure was in judgment.
*
Gerry Grossnegger - 2010/10/25 19:06:34 UTC
What it really sounds like is a release failure.
*
Jeff Nibler - 2010/10/25 19:16:36 UTC
Marc Fink - 2010/10/24 22:17:49 UTC
...
That's exactly what I was thinking... who says the student was able and willing to go to the instructor more often than he did? Or was progressing quickly enough for longer air time? Or that the weather was cooperating when the student was available?! Where I trained, some people took years to get their H2 while others got it in one week... same school, same training methods, same everything. Student participation, availability, and conditions at time of availability have a huge impact. Why assume the instructor or his program was the bottleneck?
*
Gregg Ludwig - 2010/10/25 19:43:50 UTC
The dead pilots instructor reports 6 lesson days over a 9 month period including 36 tows resulting in:
-about 10 min. of airtime
-no ratings
-fatality
I feel it is safe to assume the training program had deficiencies.
*
Gregg Ludwig - 2010/10/25 20:05:14 UTC
I would agree and support a quality low and slow training method to introduce the fundamentals of hang gliding, for many reasons.....but geez an introduction shouldn't take 9 months and result in only 10 min of airtime. Modern training programs and equipment can achieve results much more quickly than what this pilot experienced.
*
Sam Kellner - 2010/10/26 00:00:55 UTC
Gerry Grossnegger - 2010/10/25 19:06:34 UTC
What it really sounds like is a release failure.
Yep, nothing that I've heard yet really defines what release, if any, he had.
Release failure or failure to release, then nosing over. There was a report that said he attempted to cut loose with his pocket knife
I doubt I could pull that off, not from 250'.
It would be interesting to see a picture of his winch he made and what type of release.
Tragic.
*
Davis Straub - 2010/10/26 01:43:31 UTC
Hewitt bridle?
*
Davis Straub - 2010/10/26 05:49:12 UTC
Revised Accident Report 10-24-10
This letter is a follow-up of my original accident report of Lemuel Lopez's fatal hang gliding accident in order to confirm and correct various aspects of that earlier report. After interviewing the witness, consulting with the police investigator, and inspecting the equipment and crash site, I believe the following facts are in evidence:
On October 13, 2010, at approximately 6:30 pm CDT, Lemuel Lopez age 45 was killed while towing a Wills Wing Falcon hang glider on a public road just north of Edinburg, Texas. Prior to the accident, he had taken 6 hang gliding lessons from me and logged some 38 flights totaling about 10 minutes in 9 months. He had progressed to the point of towing up to as high as 100 ft with consistently good foot-launchings, climb outs, straight flights, releases, and landings. He was able to handle and make corrections for light turbulence, mild wind gradients, and slight cross-winds, but he had not advanced to the point of making major corrections or banked turns. He was progressing well in ground school and was fully aware of the risks of trying to tow on his own. That was why he was taking professional lessons and why he tried very hard to duplicate the system he was training on and to follow the procedures he was learning. Unfortunately, the system he had acquired was unproven and the experience he had acquired was inadequate for him to properly evaluate the weather conditions and to tow safely on his own.
Only after the accident did I learn that his primary release was a make-shift "Linknife" constructed from a thin plastic tube with two single-edged razor blades inserted parallel to one another inside. It was activated by a rope attached to the pilot's harness on the left side, similar to the way he had been trained. His secondary release was a high quality folding utility knife with the standard one-inch blade. His payout winch was home-built with a wheel for adjusting the brake tension but with no emergency tension release and no hook knife to cut the line.
On the evening of the accident, the pilot and driver setup the towing system, adjusted the winch tension, and tested the pilot primary release several times to see that everything was working properly. The winds were reported to be variable with maximum speeds estimated to be below fifteen miles per hour. The pilot was eager to fly, but waited until a lull in the wind before giving the signal to accelerate. The pilot launched westward on an east-west paved roadway with grass fields on both sides. The take-off was good and the pilot climbed to approximately 25 ft with a ground speed of 20 to 25 mph before drifting to the right, out of sight of the driver who was looking through the rear-view mirror. The driver immediately looked over her shoulder only to see the glider in a steep bank to the right. By the time the driver could stop the pickup, the glider had crashed in the grass field approximately 100 ft to the right side of the tow road.
Inspection of the equipment after the crash showed that the right wing had broken where it joins the cross-bar, that the keel had broken near the hang point, and that the control bars had been mangled. An autopsy revealed that the right side of the pilot had numerous broken bones and that there was a severe head injury in spite of the pilot wearing a safety helmet. Inspection of the site revealed that the towline was approximately 250 ft long at the time of the accident and lined up with the crashed glider with its free end approximately 100 ft from the glider. The weak link had been cut and was lined up with the glider and towline, approximately 30 ft from the glider.
Analysis of the above facts suggests that the primary cause of the accident was the weather conditions. Although we do not know the direction of the wind at the time of the accident, the fact that the pilot launched westward suggests that the wind at the time of take-off was from the west. However, the prevailing wind at that location is from the southeast, so there is a reasonable probability that the wind at 25 ft was stronger than that at take-off and from the left. If that were the case, it would have caused the glider to drift and bank to the right as observed. In any case, the fact that the wind was variable with speeds approaching 15 mph would likely have produced a significant wind gradient when launching from a lull. Even if the wind gradient were head on, it would have caused the glider to climb rapidly and the pilot to pull in hard on the control bar to keep from climbing higher. In either case, if the pilot had tried to release at the first sign of trouble as he had been trained to do, then he would have taken his hand off the left down tube long enough to release. If his make-shift release failed to release immediately, his continued pull-in on the right side of the control bar would have produced a strong roll and turn to the right as observed. The amount of time from the initiation of the roll-out until the impact on the ground could only have been a matter of seconds, probably about 5 seconds. The glider would have accelerated during the roll-out and the pilot would have impacted on the ground head-first on his right side at approximately 40 mph. It is doubtful that the pilot had time to even consider using his back-up release. In all probability, the primary release finally functioned immediately before impact or upon impact, cutting the weak link too late for the pilot to have any chance of recovery or survival.
Donnell Hewett
*
Sotos - 2010/10/26 13:00:56 UTC
Donnell Hewett - 2010/10/19 13:21:59 UTC
He continued to fly straight ahead with the towline draped over the control bar still attached to the pickup. When the towline tightened, the glider nosed down and the pilot crashed head first into the ground. He was killed on impact.
I am not experience in truck towing but I have done the training with this winch some years ago. I was using a maisons 3 loop release. This release is set to pass under the control bar and attached to the hips.
Question: Is there any kind of release for truck towing that is set to pass over the control bar? If not then how this glider nosed down after a tightening of the towline?
*
Dallas Willis - 2010/10/26 13:57:48 UTC
Donnell Hewett - 2010/10/26 05:49:12 UTC
Analysis of the above facts suggests that the primary cause of the accident was the weather conditions.
You've got to be kidding right?
The primary cause of the accident was the man's own overconfidence in his meager abilities. This has nothing to do with the quality of instruction, the wind, the glider, the weaklinks, etc. Nothing other than the fact that he made a mistake and thought he could fly a hang glider on his own.
*
Sotos - 2010/10/26 15:38:27 UTC
Within this restricted experience of truck towing I know that the towline is passing under the bottom bar. If you do the mistake to pass the towline over the bottom bar instead, then in any case you fail to release or cut the line while it is tighten, you will have a nose down crash caused from the pressure of towline over the bottom bar regardless if your experience pilot or not.
An alternate way of payout winch towing, is to launch from a dolly or foot from 100m or so behind of a truck. With this method you use the two stage (or Koch) release that is set with one shorter rope over the bar and one longer under. When the line angle is increase as much as to contact the bar you release first the shorter one (over the bar) and finally the lower one. This kind of launch might not be considered as a truck towing or platform launch. Although you use the same winch, as soon as I know the truck towing or platform launch is the launch from a truck or a trailer (platform) behind the truck.
This report is clearing that:
He continued to fly straight ahead with the towline draped over the control bar still attached to the pickup. When the towline tightened, the glider nosed down and the pilot crashed head first into the ground.
If this launch has been performed from a platform or truck then a passing of the towline from the wrong side of a bar could be one of the reason of this accident.
*
Davis Straub - 2010/10/26 15:51:12 UTC
In Hobbs New Mexico I foot launched behind a payout winch (ATOL) truck with about 100 feet of rope out. The rope was below the bar. The winch was not tightened enough and I had to have them tighten it up a bit as I ran so I could get off the ground.
*
Mike Lake - 2010/10/26 18:44:20 UTC
I suspect there is little or no advantages in having the towline under instead of over the base-bar in a trailing line snag situation.
In either case the glider is going to nose in. It might take a fraction longer if the pilot is not holding onto the base-bar, but basically I suspect whatever, the glider is going to rotate around the rapidly decelerating or halted pilot.
I can only agree with Dallas Willis. How the weather is singled out as the primary cause amongst the list of accidents in waiting is beyond me.
I get the impression that it is not uncommon (correct me if I’m wrong) to have just a driver and a pilot with the various payout systems in the US, with no separate winch-man.
I can’t imagine not having a winch-man giving me his exclusive attention and ready to reduce, back-off, abort or cut if things get out of hand.
Us UK flyers are either a bunch of wooses or you US guys are a super brave outfit.
*
Mike Bomstad - 2010/10/27 06:53:40 UTC
.l
---
Last edited by Mike B on 2010/10/28 03:03:06 UTC; edited 2 times in total
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Doug Doerfler - 2010/10/27 12:51:30 UTC
Analysis of the above facts suggests that the primary cause of the accident was the weather conditions.
You've got to be kidding right?
By these standards anything that ever happens can be weather conditions
- I was at the top of a loop and just lost air and fell into the sail
- I was flying very close to the hill in thermal conditions and a random gust of air lifted one wing
- That thunderstorm just came out of nowhere (I know this has been used)
- I had a really nice tail wind on launch, I don't understand why I crashed into the rocks
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Sotos - 2010/10/27 14:00:18 UTC
Mike Lake...
I wouldn’t disagree with what you state about a trailing line snag situation. However I would not set anything in stone or between black and white if I would judge a situation that it could cause an accident.
If this glider was not more than 100ft as it is reported then it could be possible to lose some height down to 60-70ft before to stop to fly. With the towline behind your body is possible to have from this height a stall and nose in, in lower height and probably a quite hard impact even the large sail area of this beginner’s glider not excluding the possibility of fatally accident any way, but with more possibilities to save something rather than an opposite case to have the towline over the bar. With the towline over the bar in any case would result in an accident caused from something more like a free fall.
Further about trailing line snag situation I wouldn’t say that in any other case the result is always the same. The possibilities to avoid something having the line behind your body are not the same if you snag it for example in a small bush that is possible to release it with a tension just below the limits to stop you to fly and I wouldn’t compare it with an opposite case of a towline that is pulling backwards and with the same tension over the control bar.
Any way what I want to state above is that any possibility that is tending to apply an out of the limit back bar pressure is always a cause of a catastrophic situation not excluding many incidents with drogue chutes that passed accidentally over the bar.
I agree as well with your concern about the requirement of another one person for an inclusive attention in order to avoid any happening.
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Steve Seibel - 2010/10/27 16:23:10 UTC
amazing
Gregg Ludwig - 2010/10/25 19:43:50 UTC
I feel it is safe to assume the training program had deficiencies.
I was shocked to read this and a few other similar posts on this thread. Maybe there is more that you want to say about this instructor that you are not saying. Or maybe not. To those of us who are only going by what we have read here, your comments are pretty incredible. The guy goes off on his own for unsupervised winch towing with home-made gear, way over his head, and you blame the training program, which the guy didn't bother to take the time to pursue to completion, nor did he bother to attend frequently enough to have any realistic hope of a steady upward learning curve?
And these glib comments, in the context of a fatality? Incredible...
PS I appreciate Donnell's report and his assessment of the proximate cause of the accident as being weather conditions beyond the pilot's ability to deal with while towing. That's not the same as saying that "the guy was doing everything right and a freak gust hit him." Obviously other mistakes were made-- e.g. the decision to fly unsupervised-- that contributed to the situation, and Donnell never implied otherwise.
PPS Maybe by "training program" you meant the deceased pilot's own training history and whatever "program" he had for himself in his own head, rather than the "program" that his instructor would have offered him. If so, sorry, but that's not the way it came across to me, and I can only imagine how the instructor would feel on reading something like that in this tragic situation.
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Jerry Forburger - 2010/10/27 18:00:37 UTC
Donnell could be (and probably is...) exactly correct in his analysis of the cause of this accident, but there could be other factors.
All of the posted evidence can also describe the classic 'lock out' which can be enhanced by the above mentioned weather factors.
The cause of this tragedy is a pilot flying outside his own limitations of skill, knowledge and judgement. (Thanks Mike Meier)
Stupid is as Stupid does... and that's all I got to say about that.
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Gregg Ludwig - 2010/10/27 21:12:27 UTC
The reports suggest to me that after the student pilot completed 6 days of lessons over a 9 month period he didn't learn squat from this instructor.
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Gregg Ludwig - 2010/10/27 21:33:12 UTC
Jerry Forburger - 2010/10/27 18:00:37 UTC
...
It is always so easy to just blame the dead pilot...call it pilot error. End of story.
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Davis Straub - 2010/10/27 22:39:04 UTC
Well it is pretty clear that in fact it was quite a few pilot errors that lead to his death here as opposed to equipment failure (which would be the other option, or perhaps unsafe flying conditions, which in this case would point back to pilot error). Now pilot error is a broad category and what we are most interested in is what pilot errors were they and how to avoid them in the future.
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Gregg Ludwig - 2010/10/27 23:14:59 UTC
Yes, the pilot made several errors. I feel that the fact that so many errors were made reflects poorly on the quality of instruction received over a period of 6 lesson days over a period 9 months. Several effective ways for new pilots to avoid pilot errors/accidents are:
-obtain quality instruction (good instructor/ good equipment/good method of teaching/ good location and conditions)
-follow ushpa guidelines for skill level (instructor discussion topic)
-novice pilots fly and learn under supervision (instructor discussion topic)
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Gregg Ludwig - 2010/10/28 00:30:36 UTC
Steve Seibel - 2010/10/27 16:23:10 UTC
...and I can only imagine how the instructor would feel on reading something like that in this tragic situation.
I can only imagine how the pilot's friends and family feel, especially with them likely knowing that he had been taking HG lessons for months.
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Rob Clarkson - 2010/10/28 01:31:40 UTC
Gregg get off this topic you have no clue what you are talking about. If he had six lessons in a week perhaps he'd have a few skills. Six lessons in a month he may be showing some progress. Six lessons in Nine months!! He has no more skill than some one who has never taken lessons. To suggest this is the instructors fault is insane. If you think he would have been better served by scooter towing you are sadly mistaken. This would have only provided a different method for which to kill himself. As I posted earlier all of us who are hard core and really want to fly have probably done some stupid shit. Most of the time we get away with it some times we don't. Sadly this time it was fatal.
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Davis Straub - 2010/10/28 01:45:02 UTC
Upset stomach, Rob?
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Gregg Ludwig - 2010/10/28 02:57:09 UTC
While this accident is not the instructors fault, especially since he wasn't even there, the facts seem to indicate poor training, a likely contributing factor.
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Steve Davy - 2010/10/28 03:20:39 UTC
What " facts" would you be referring to ? How many actual facts do you ( we ) have on this ?
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Steve Seibel - 2010/10/28 03:46:10 UTC
Gregg is an instructor in Texas-- I just checked the USHPA website-- I remember his name came up on the hanggliding.org forum when someone posted about how he kept emailing and calling Gregg with no response and was seeking other recommendations for instructors. Not that that has anything to do with this, that's just why his name stuck in my head.
To have an instructor say things like "he had been taking HG lessons for months" about a guy who had only taken 6 lessons, is beyond bizarre.
It boggles the mind, how completely unprofessional some people in this sport are. Compare and contrast to the GA world -- imagine some guy had taken 6 flying lessons and went out to fly solo unsupervised without permission and crashed and some flight instructor says "he had been taking lessons for 9 months and didn't learn anything, there was a deficiency in his training." The guy would be laughed onto the next planet!
I expect crap like that from experienced pilots who aren't used to dealing with new students and forget all the pitfalls a new student can get into. To them it seems so natural, they forget all the mistakes that can be made and they are willing to huck someone off a mountain way before they are ready and all kinds of other crap. But from an instructor!
Unbelievable.
Maybe you know something more that you aren't telling, Gregg, but judging only by what we've read so far on this thread, your comments seem utterly without merit...
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Davis Straub - 2010/10/28 04:17:26 UTC
I see that that bug is going around.
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Rob Clarkson - 2010/10/28 05:48:29 UTC
Ok Greg, what indicates to you poor instruction? I'll tell you why I don't think any instructor wouldn't have any success with any student. Any one who teaches anything will tell you a very high percentage of what is taught is forgotten with in 48 hrs. The second time it is taught they retain more and so on. The longer between lessons the less information is retained there fore you are going to need to reteach the entire lesson and still much of it will be forgotten.
Best case this student had six lessons all in one week. That way each lesson is fresh in his memory and he is able to learn new things each day. Nine months later how much is he going to remember. More likely the lessons are spread out. So your not even getting one lesson a month. Even the most talented student isn't going to retain much skill doing less than one lesson a month.
Living in Canada our winter season is six months we can't fly. After flying for ten years and getting over 100hr/year the last couple years, I still feel a lot of rust in the spring after not being able to fly for six months over the winter. I can imagine how poor some ones going to do with 10min air time over nine months. So please explain to me how this pilot had obvious poor training.
BTW I have no idea who this pilot was or who was trying to teach him. All I know is what was posted here and my own personal experience flying and teaching.
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Peter Birren - 2010/10/28 13:44:28 UTC
Some 15 years ago in Illinois, there was a similar fatality. The pilot was someone who would not take advice - very headstrong - because after a few lessons, he knew everything. In the accident, he used a 2:1 bridle, a home-made 3-string release, no radio and maybe 250' of towline; told the driver to stop when he got high where he'd release and land. On the last flight, the release failed and he pendulumed into the ground nose-first. The similarities to what I've read about this latest one are amazing. However, there was no definitive description of the bridle used... just conjecture.
I was also amazed to read ... his primary release was a make-shift "Linknife". As the inventor of the real Linknife, this concerns me for several reasons. I know that Don Hewett has several of them, that he's a big fan of its simplicity and ease of use, and that, to date, this is the first fatality since introducing the release in 1996 (or was it '95?) in which one (or a make-shift one) was involved. I don't know any more than what's been written here and so won't speculate why he couldn't/didn't release.
Blame on a bunch of different things have been thrown around but it was ultimately the pilot who did not learn enough before venturing off on his own, using home-made equipment and untrained crew. Is it any wonder the result? Perhaps an alternate subject line could be "Hey, watch this!"
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Gregg Ludwig - 2010/10/28 15:46:59 UTC
Rob Clarkson - 2010/10/28 05:48:29 UTC
Ok Greg, what indicates to you poor instruction?
Here is another report from a student (H-0) (Al Hernandez) that may shed some light on the methods of instruction used. This student weighs about 250 pounds and was using a glider too small for his first tow over asphalt as reported.
Who is flying in Texas this weekend?
28th and 29th I will be up in Kingsville, at the Kleberg County Airport about 8 am. I will be training With the Doc. He will be having lessons there Saturday, depending on weather conditions, will be towed up with a tow winch, this will be my first tow. Have just been doing foot launch, will get some airtime in on those days.
I now understand of having the right HG for the right size of person. I can't say you didn't tell me so, cause you. Saturday 29th 2009 time 11:45 am using a WW F 160 way too small for me, but that was all there was for training at Kleberg County Airport at the time, I can't not run 35 MPH that the WW-F-160 needed for airspeed, I was braking up at 25MPH.
My ground experience was real good ( A-plus), and nerver crashed, or wacked the glider. Using a payout winch, this device is a trip, it is nothing like foot launching from a hill at all, nothing like walk, jog, and run, like I was taught in the past. The payout winch is more like RUN LIKE HELL. Once your body weight pressure is taken for the payout. my payout pressure was 65 lbs. Lighter pilots 55 lbs. I had to stand like a post, and not move at all once the truck took off at 25 mph with one foot in front of the other, and I am still standing in the same place leaning back, with the payout feeding me line, and there is a strange feeling, odd feeling to being pulled by the payout. Then I take the first step to the run, and i am now running 25 Mph, I am thinking, oooOOOOH SH#T, hope I don't have to run that far, hoping the HG gets lift so I don't have to run no more... my F-A running down the runway like a rocket there is no wind, I have the right angle of attact the HG is up, but still not enough lift for the pilot, I can't reach my Cut line, cause I have both hands on the downtubes, and if I let go of the Coke bottle grip I will crash, I feel like pushing the HG into the air, or jumping up so it can lift, but I do not, that would make my situation worse, I feel I am about to fall into the asphalt face first, and crash, I am at my run limit, and feel I can not take another step, still Hg not lifting me, the winch operater lets go of the pressure of the payout winch, my run comes to a jog, and to a stop and drop to my keens. Payout winches are odd. The HG got lift but, couldn't lift me in no wind conditions, the HG was too small in the first place. This was a trip, and a HG experience "Hang gliding for dummies." the glider would had taken me up if there was a 10 to 15 MPH wind or maybe a hurricane in the area.
I am still pondering about the Payout winch, I did a few more runs, but did not lift. Should I do it again??????
Yes, I think I should. An odd feeling for Payout winches, but with the right glider WW-2-225, and the right wind I should be airborne ; )
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Sergey Kataev - 2010/10/28 17:09:33 UTC
Condolences to the pilot's family
Yes, he shouldn't have gone out on his own with this kind of experience - that probably is the main cause of the accident, but...
Mouth is quick to open and one doesn't need to take hands off control bar to release: a mouth release _could_ have saved his life.
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Steve Seibel - 2010/10/28 18:31:11 UTC
Sure, its hard to make progress with the wrong equipment. That's not the same as being taught specific techniques that are substandard and dangerous.
Between the mashed-up writing style and my lack of knowledge about these towing methods, I can't really make heads or tails out of the quote you posted, except that the glider ("WW F-160" --??) was too small, and/or the truck not driving fast enough for the glider / pilot combo.
Maybe you should start a new thread entitled "Donnell Hewett uses substandard equipment and techniques" and tell us more about why.
It sure looks to me like you are mixing apples with oranges and jumping to conclusions in the interest of grinding your axe. This guy goes into do-it-yourself mode and kills himself and you immediately point the finger at the instructor who he has only seen six times in nine months. Is there any hope of anyone generating an unbiased accident report that we can all learn from, with attitudes like that?
An instructor doesn't have any obligation to teach. If the instructor is only available for 6 lessons in nine months (which no one was saying was the case here) that doesn't force anyone to go out and learn on their own. That guy who was so frustrated because you wouldn't return his calls and emails, was he supposed to go teach himself also? I'm sure there's more than one instructor in Texas.
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Mark G. Forbes - 2010/10/28 21:16:38 UTC
Gentlemen,
I would ask that you please take this entire "who's to blame" discussion completely off-line and private. Gregg, as a former BOD member you're familiar with some of the legal and liability challenges we face, and this discussion is venturing into an area that I would really prefer that it should avoid.
The facts that we know are that a student with few lessons, minimal airtime, home-made equipment and an untrained driver attempted to go towing on his own, and paid the ultimate price. His reasons for doing so are based on speculation. If there are first-hand observations of poor instructional practices which are relevant to an instructor's performance, they should be communicated to our safety and trainung committee, and not bandied about in public. That information should come directly from witnesses, not through third-hand reports.
Mark G. Forbes
USHPA insurance chairman
USHPA Director At Large--Region 1 (OR/WA/AK)
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Marc Fink - 2010/10/28 23:40:21 UTC
Well said Mark--this is wandering onto legal thin ice.
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Gerry Grossnegger - 2010/10/29 03:30:42 UTC
To hell with legal, we can talk all we want and it won't make any difference to anything that's happened, but MAYBE we can reduce the chance of something like that happening again if we can figure out exactly what happened.
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Rob Clarkson - 2010/10/29 06:20:13 UTC
I'm sorry Mark I just couldn't let Gregg’s comments go unchallenged. They were irresponsible irrelevant and very inconsiderate. He seems to know the instructor and has opinions based on other events. They are not relevant to this accident. Jerry I hope you are just kidding, it's hard to tell. What needs to be learned here? It really starts and ends with the fact he didn't have enough training to go out on his own and tow. You want to talk about faulty releases and winch’s so that some other student with six lessons can read this and go oh that's what he did wrong and go off and try it on his own. The results will not end well.
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Marc Fink - 2010/10/29 09:47:37 UTC
Gerry Grossnegger - 2010/10/29 03:30:42 UTC
...
Agreed--but Mr Ludwig--who I seem to recall chaired USHPA's towing committee as of last year--was seemingly laying the blame for this at the feet of the instructor who wasn't even there at the time of the accident. This is indeed a public forum and his comments can be construed as defamatory, IMO.
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Sam Kellner - 2010/10/31 01:26:06 UTC
Davis Straub - 2010/10/28 01:45:02 UTC
Upset stomach, Rob?
Probably, because his ignorant (lack of info) remarks are FoS too!!
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Marc Fink - 2010/10/31 13:23:22 UTC
A Texas contingent showed at Lookout's party last night--including school/tow operators and a pilot familiar with the accident victim. They all believe the cause was error in judgment on the the part of the accident pilot. What info are you referring to that they apparently do not know of?
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Rob Clarkson - 2010/10/31 21:54:20 UTC
Besides lack of info what ignorant FoS comments are you refering to? Perhaps I need to explain myself better.
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Wescanfly - 2010/11/01 00:54:20 UTC
When, Mr. Hewett posted, his primary release was a make-shift "Linknife" Does this imply the pilot fabricated a release or that he was using a genuine "Linknife" and that Mr. Hewett considers it sub-par. I have used a Linknife for years and it is anything but make-shift
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John Haig Thompson - 2010/11/01 11:18:32 UTC
From page3 of this thread, it does sound a home made "Linknife"
Revised Accident Report 10-24-10
Only after the accident did I learn that his primary release was a make-shift "Linknife" constructed from a thin plastic tube with two single-edged razor blades inserted parallel to one another inside. It was activated by a rope attached to the pilot's harness on the left side...
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Steve Seibel - 2010/11/01 17:28:43 UTC
toward a higher standard of discourse
May I suggest that we review the whole thread more carefully before thickening the plot with more questions-- I think the earlier post by Peter B. answers the question you, Wes, asked.
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Christian Williams - 2010/11/01 18:14:11 UTC
Personally, I don't think there is much to learn from this particular accident.
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Davis Straub - 2010/11/01 20:21:28 UTC
Personally, because you already learned it?
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Quinn Cornwell - 2010/11/01 21:30:41 UTC
Seven pages already... who would have thought.
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Christian Williams - 2010/11/01 21:30:43 UTC
No, because there are so many oddities to the particular situation that it doesn't say much about towing, instruction, safety, appropriate glider size, or the responsibility of instructors. Most accidents I can learn from, but this accident chain has too many kinks.
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Doug Doerfler - 2010/11/02 07:37:04 UTC
We have the results of a 10 minute airtime pilot building his own tow rig and using it for the first time with a driver with zero experience.
I'd say there is alot to learn in that
I towed with the boys and girls in Canada a few seasons, there was alot of time, effort, experience and pride that went into their tow rigs and a significant amount of time and effort into training a new driver.
What we can learn...we all have screwed up once in a while, but you start piling on the bad decisions and the chances of it all working out go in the toilet real quick
But the #1 root cause...this 10 minute airtime pilot had no idea how many bad decisions he was stacking up
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Brian McMahon - 2010/11/02 16:15:20 UTC
Literally the only thing I can think of is 'don't do what he tried to do'. Christian is right, this situation is such an abberation that there is little purpose analyzing all of the details. If somebody was walking on the roof-edge of a tall building and fell off to his death, would you analyze his walking technique, his shoes, the weather conditions, the surface of the roof he was walking on, whether he had more weight in one pocket than another; and then try to find a rational explanation of what went wrong? It's pointless, he shouldn't have been there in the first place.
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Wescanfly - 2010/11/05 00:18:26 UTC
Steve Seibel - 2010/11/01 17:28:43 UTC
...
Point well taken. Wes
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Below... All 26 participants with all save two identified by actual name listed in order of their first appearances with all their subsequent posts listed sequentially directly below. Posts in which Donnell's being filtered by Davis are attributed to Donnell and, of course, they will have been clicked out well prior to the time stamps.
2010/10/19 13:21:59 UTC - Donnell Hewett
2010/10/20 02:27:23 UTC
2010/10/21 16:31:43 UTC
2010/10/26 05:49:12 UTC
2010/10/20 03:47:23 UTC - Gerry Grossnegger
2010/10/25 19:06:34 UTC
2010/10/29 03:30:42 UTC
2010/10/20 07:36:24 UTC - Marc Fink
2010/10/24 15:12:20 UTC
2010/10/24 22:17:49 UTC
2010/10/28 23:40:21 UTC
2010/10/29 09:47:37 UTC
2010/10/31 13:23:22 UTC
2010/10/20 15:11:04 UTC - Dallas Willis
2010/10/26 13:57:48 UTC
2010/10/20 15:46:37 UTC - Brian McMahon
2010/11/02 16:15:20 UTC
2010/10/20 18:44:20 UTC - Jim Rooney
2010/10/20 23:44:40 UTC - Rob Clarkson
2010/10/28 01:31:40 UTC
2010/10/28 05:48:29 UTC
2010/10/29 06:20:13 UTC
2010/10/31 21:54:20 UTC
2010/10/21 15:47:05 UTC - Davis Straub
2010/10/24 15:27:32 UTC
2010/10/26 01:43:31 UTC
2010/10/26 15:51:12 UTC
2010/10/27 22:39:04 UTC
2010/10/28 01:45:02 UTC
2010/10/28 04:17:26 UTC
2010/11/01 20:21:28 UTC
2010/10/24 13:16:14 UTC - Gregg Ludwig
2010/10/25 19:43:50 UTC
2010/10/25 20:05:14 UTC
2010/10/27 21:12:27 UTC
2010/10/27 21:33:12 UTC
2010/10/27 23:14:59 UTC
2010/10/28 00:30:36 UTC
2010/10/28 02:57:09 UTC
2010/10/28 15:46:59 UTC
2010/10/24 14:48:32 UTC - Bille Floyd
2010/10/24 16:08:58 UTC
2010/10/24 16:14:52 UTC - Sam Kellner
2010/10/26 00:00:55 UTC
2010/10/31 01:26:06 UTC
2010/10/25 19:16:36 UTC - Jeff Nibler
2010/10/26 13:00:56 UTC - Sotos
2010/10/26 15:38:27 UTC
2010/10/27 14:00:18 UTC
2010/10/26 18:44:20 UTC - Mike Lake
2010/10/27 06:53:40 UTC - Mike Bomstad
2010/10/27 12:51:30 UTC - Doug Doerfler
2010/11/02 07:37:04 UTC
2010/10/27 16:23:10 UTC - Steve Seibel
2010/10/28 03:46:10 UTC
2010/10/28 18:31:11 UTC
2010/11/01 17:28:43 UTC
2010/10/27 18:00:37 UTC - Jerry Forburger
2010/10/28 03:20:39 UTC - Steve Davy
2010/10/28 13:44:28 UTC - Peter Birren
2010/10/28 17:09:33 UTC - Sergey Kataev
2010/10/28 21:16:38 UTC - Mark G. Forbes
2010/11/01 00:54:20 UTC - Wescanfly
2010/11/05 00:18:26 UTC
2010/11/01 11:18:32 UTC - John Haig Thompson
2010/11/01 18:14:11 UTC - Christian Williams
2010/11/01 21:30:43 UTC
2010/11/01 21:30:41 UTC - Quinn Cornwell
Note that while the title of this 2012/08/10 04:35:22 UTC founded topic is "Skyting demolition" the major founding mission of Kite Strings was Skyting demolition. And Kite Strings is really just a continuation of the warring against Skyting I've been doing since just before my first tow on 1980/11/14 - several weaks before Donnell would submit his articles to u$hPa. I did not like being told I'd be OK foot launching on a winch with a Reliable Easily Reachable Release. Donnell didn't either and solved the problem by incorporating an Infallible Weak Link.
I was working on engineering better and better release solutions from the early Nineties on until I'd totally nailed it not long before the Skyting philosophy motherfuckers ended my active flying career at the end of the 2008 season. The better you build the mousetrap the more the Skyting based shitriggers are gonna piss all over it and you.
I was battling the Houston wire u$hPa operatives and their pet douchebags before, through, after this Hewett product impact until they cut my wire and its forum moderator wanted to continue a rational discussion without having it sabotaged by u$hPa operatives and their pet douchebags.
This crash with its Davis Show discussion WAS the demolition of Skyting and Donnell - as we just now realize - and Zack Marzec 2013/02/02 was the demolition of the Infallible Weak Link. But the legacies and influences will be around until the end of time. Anything that can make thirty tows without killing someone at Three or better level will be retained to build up a long enough track record to be embraced by the community as typical at the least or Industry Standard at the best.
Another archive project - two and a half days of pure unmitigated hell. I guess there was a time when these email list servers had their place but it was well over at the point this discussion started up. Even if the entire post is "Thanks Don, Tracy" it still eats up at least five minutes to harvest the click in time stamp and get everything properly formatted - and that's when your vision WASN'T fried three hours ago.
There's a really heavy concentration of relevant posts, discussions on Peter's dump from his Golden Era - from the beginning at the end of 2000 through to about half past 2012. It's all towing so that tends to eliminate the two hundred posts threads on flare timing perfection we tend to get in the general hang gliding mutual masturbation societies and most of the participation is from tow operators which make the lunatic statements a lot more enjoyable/damaging.
Zack C - 2011/01/10 14:28:40 UTC
When I first saw your release years ago on the Oz Report forum my impression was the same as most people's. I didn't know what the pictures were showing but it looked way more complicated than it needed to be. After seeing the problems that even the best releases on the market have and learning more about your release, however, I understand why you made it the way you did and the advantages it provides.
Designing and producing a really clean and totally bulletproof two point AT release system requires - if I do say so myself - five or ten times the brains, engineering, precision, effort, time it does to do the fuckin' glider itself. That's why there have NEVER been - and never will be - good widely available solutions. (The Brooks Bridle, Koch two stage, Kaluzhin, Joe Street get asterisks.)
Much easier to throw a loop of fishing line into the easily reachable mix; pray that it will break before you can get into too much trouble; assure your customers, students readers that it will; attribute anything bad that happens on pilot errors, poor judgment, obliviousness to the dangers of the situations, invisible dust devils.
Donnell comes along with his physics PhD and mostly clueless take on aerodynamics, moves the lower connection from the basetube to the pilot, puts a number - 1.0 Gs - on the weak link, declares all of our problems solved.
And that helps the dregs who've ALWAYS been in control of the sport consolidate and fortify their positions of power. Trust us - we know what we're talking about.
And we get DECADES of snake oil salesmen and customers engaging in total lunatic discussions about the best ways to tweak weak links to exactly 1.0 (for your average glider) in order to get them to do what the great Dr. Lionel D. Hewett, PhD assures us they will. I'm guessing your average higher profile tow pilot has a hundred times the hours he has in the air spent in discussing weak links. (I'm sure I have many thousands.)
Then a bit over thirteen years ago T** at K*** S****** gets his brain mostly freed up from zombie mode, starts making waves, gets kicked out of the sport a couple years later. 2010/10/13 a Hewett product eats it, everybody gets to see just how safely and competently Donnell's implementing tow training. Russell's finally forced to tell people to double them up in the summer of 2011 after an inconvenience sends a hotshot pro toad to the emergency room; Trisa's gotta write a fourteen page magazine article 2012/06 on how to tie the 130 pound Greenspot fishing line everybody's forced to use so that it breaks more consistently within the FAA legal range; eight months later an increase in the safety of the towing operation totally splatters Zack Marzec, many of us become happy with doubled up Standard Aerotow Weak Link, the conversation's abruptly and permanently over and nobody can remember anything he or she ever said about weak links.
So let's remind everybody and archive a lot of this discussion out where non Peter approved glider people and the public at large can freely and easily read this stuff in context without getting totally lost and going half blind.
Everything's in the "Weaklinks" discussion - 57 posts - unless otherwise noted. "Weaklinks and aerotowing (ONLY)" - nine posts. "Want to buy (WTB) Weak link tester" - two posts. I may amend this archive after the couple of years it'll take me to remember what a monumental pain in the ass this project was.
Donnell had been my Numero Uno hero in the sport until after my flying career had been ended and Mike Lake...
...started waking me up. And I DO feel a bit queasy ripping someone to shreds who took the time and effort to listen and respond to me and express appreciation for my efforts. But he wasn't really listening and responding to me and he didn't do shit in the way of giving me covering fire against the u$hPa, Flight Park Mafia, Peter, Davis, Houston Shows assholes with whom he was aligned. And we really need to finish driving stakes through his heart and the heart of the total crap he dumped on the sport to such devastating effect.
If you're registered with or have some means of accessing Peter's dump you can use the four digit code included with each post to navigate to the original.
In our recent discussion about weaklinks I wrote that we use 22" of dacron kite string. Make that 18" (before tying). Just got a 1000' roll and pulled out a super-simple tool, literally a 4-nail "loom."
About 1/2" apart by 17.5"
4 #6 finish nails in a 1x2.
I cut up the whole roll in a half-hour. Produced 650 weaklinks for less than $20. Do the math... 3 cents each.
Tie a clove hitch on one nail. Wrap around 25 times and cut. Cut between the close-together nails. Makes 50 links. Tie the whole bundle in a single overhand knot. Give to club members. Keep stored material clean, dry (in a zip-lock) and out of the sun.
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Stuart Caruk - 2003/12/22 04:19:51 UTC
3961
I received the following message today at TowMeUp.com and I'm curious how many pilots actually fly without weaklinks.
The guy that sent it doesn't state whether he flies a PG or a hang glider, although I'm assuming that it must be a hang glider, given the tow forces used, and the comment about angle of attack not increasing with an increase in tow force. This of course is controllable by the pilot and may not be true in a hang glider, but in a paraglider, when the tow force increases it definately pulls the pilot forward, and the glider goes to a higher angle of attack.
Anyway, my towing-club has decided that a weak link gives more trouble than it solves. So we fly without a weak link. Instead, a DHV-approved winch should have a "operator adjustable maximum towforce".
I think that the angle of attack does not increase when the tow-operator increases the tow-force beyond what you use. (we disagree on this issue, I know...)
We tow with just below 200 pounds for light pilots and over 260 for heavier pilots.
I absolutely agree that a decent winch should automatically limit the tow force. Ours is designed to limit the maximum force to that dialed in by the pilot, AND you can easilly set the pilot operated pressure refief valve so that an inexperienced tow tech can't easilly overtow a pilot.
Of course skipping the weaklink is IMHO a very bad idea. The weaklink is designed to blow out like a fuse or circuit breaker in a modern electrical installation. Look in any house or business, and you will see loads of wiring running throughout the building. But you will never see a code approved installation that doesn't incorporate a fuse or circuit breaker to prevent overloading the circuit, and burning down the structure.
While I must admit, it's unlikely we'll burn down a paraglider or hanglider without using a weaklink, there are unforseen circumstances that in even the best of times a weaklink will easily prevent. A couple that come to mind would be a simple line dig, which jams the line and the pressure will dramatically rise to the breaking strentgh of the line, same thing for a line that slips off a pulley, or wraps around part of the tow vehicle when the line goes slack. A malfucntion in the tension control system causes a problem, as does a shear, or problem high in the tow with a bow in the line.
The only good reason not to use a weaklink would be if they are always breaking prematurely. Of course if the weaklink is breaking, it's almost always better off to figure out why it breaks. For example if it breaks consistently at the same height in the tow, it's likely to be caused by either a wind gradient the pilots are towing through, or a line dig in the spool. If they are breaking randomly, it could be because the weaklinks are overused, or are of poor quality. If they are breaking right off launch, particularilly with a paraglider, the tow launch technique requires some attention, because the pilot is likely being overtowed right off launch. This is of course a major problem, and probably the worst time to break a weaklink.
I would way rather run a bit further on launch then get yanked up to quickly.
I tow behind my boat a lot, and often with relatively inexperienced operators. A couple of our sites ensure that a weaklink break off laucn will result in my hitting the drink, so I upsize my weaklink and go from my standard 250 pound link, to a 350 pound link (I clip in a 347 pounds). It a tradeoff between safety in an emergency, and my desire to stay dry. I can't see a reason to not use the link in any case. Of course I used to skip the link when I scooter towed, and with an experienced operator, but after tossing my reserve in a situation that would have been a non event had I used a weak link, I'm fairly convinced of their validity.
You guys towing hang gliders have some significant advantages in that you have effective pitch control. I'm still lusting to get my hands on a cage so I can have the same, but with a bag wing.
But back to the original quesdtion...
I'm curious how many pilots actually fly without weaklinks.
Also please let me know what type wing you fly (hang or PG) and on what type of winch.
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Peter Birren - 2003/12/22 22:38:26 UTC
3962
Here in Illinois - static towing HG - we have gone back to using weaklinks after a few years of not using them. After a couple of incidents by those using them and others not, we've realized that it's an important safety item to prevent pilot injury due to a blown launch from being aggravated by being dragged, even if it's just the residual tension in the towline. Shit happens at launch, pilots stumble, winds change and a weaklink helps keep the situation from getting worse.
Once aloft, the weaklink should not cause a problem if it's sized right and tension is kept to a moderate level. And as an earlier thread showed, a weaklink is a "last chance" to get off the line should everything else fail.
There is a definite and noticeable increase in wing angle (relative to the ground) as tension is increased from initial takeoff to max. AoA appears to increase because the nose rises more, but it's due to the glider's orientation to the towline force, a "false gravity."
160-180 is a good range for average pilots; 180-200 is our max for bigger bodies. At those levels, the climb rate is 900-1400 feet per minute depending on the air and lift. More tension than that and the glider begins to deform which makes for poorer performance and not all that much more altitude gained.
Weaklinks - use 'em if you care about your safety.
What exactly is the point of weaklinks? Why should we be using them?
Peter Birren
The original purpose of a weaklink was ostensibly to prevent overtowing the glider. Dr. Hewett developed the tension sensing concept for ground-based towing to that and other problems. Aerotowing is speed controlled and so doesn't have overtowing as a major issue. However, in both general launch methods the glider is being towed close to the ground and here's where, IMO, weaklinks are an immediate benefit. Should something go wrong at launch, the weaklink will break quickly because of the sudden increase in tension. This timely break will prevent glider and pilot from being dragged and further damaged. The weaklink also offers a measure of protection to the tug pilot, especially important when near the ground.
Well away from the ground, the weaklink will not prevent a lockout but will, or should, break at some point during this radical event. It may seem a nuisance to some pilots if it breaks during a "normal" tow; it's entirely possible the pilot is not managing the tow process very well, like letting the line go slack and tightening up rapidly v/s smoothly adjusting speed changes.
What is the tradeoff in safety between breaking a weaklink and thereby having a problem, and not breaking a weaklink and thereby having a problem?
This should be a no-brainer. When the weight of Hewett's "artificial gravity" or the thrust of an aerotow is removed, the glider can more easily be maneuvered in 3-dimensional space. While teathered to a car/tug, its movements are limited by the dynamics of the towline and strange things can happen... fast.
Towing makes re-launching so easy that not being dragged along the ground is certainly worth the three cents of material and the inconvenience of having to try it again... at least the pilot has another chance when the alternative might have a much worse outcome.
We aren't Superman, nor are we perfect beings, and weather happens. A weaklink is but one piece of protection and works with other parts (sprogs, parachute, helmet, etc.) to accommodate some of our mistakes.
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Davis Straub - 2005/02/08 17:08:45 UTC
4589
Peter Birren
The original purpose of a weaklink was ostensibly to prevent overtowing the glider.
What does overtowing mean? I assume that it means the car is going too fast.
I ask this question to point out that I so much can't imagine overtowing that I don't even know what you are talking about. In other words, this is not really a problem with aerotowing.
Also, I can't imagine this "problem" being overcome by a weaklink, if they don't even work for lockouts.
Aerotowing is speed controlled and so doesn't have overtowing as a major issue.
Or any issue at all. It looks like weaklinks are a holdover from the old days.
However, in both general launch methods the glider is being towed close to the ground and here's where, IMO, weaklinks are an immediate benefit.
Ah, ha. I have this as the only reason in my article scheduled to be published in the Oz Report tonight. This seems to be the only reason for a weaklink with aerotowing.
Should something go wrong at launch, the weaklink will break quickly because of the sudden increase in tension. This timely break will prevent glider and pilot from being dragged and further damaged.
I agree. Then we need to determine how strong the weaklink should be just for this problem.
The weaklink also offers a measure of protection to the tug pilot, especially important when near the ground.
That is what their weaklink at the other end of the line is for.
Well away from the ground, the weaklink will not prevent a lockout but will, or should, break at some point during this radical event.
Rohan and others disagree. The weaklink is apparently no help in releasing from a lockout.
It may seem a nuisance to some pilots if it breaks during a "normal" tow; it's entirely possible the pilot is not managing the tow process very well, like letting the line go slack and tightening up rapidly v/s smoothly adjusting speed changes.
I've had problems when it is quite a bit more than a nuisance and I've been managing the tow force just fine, thank you.
This should be a no-brainer. When the weight of Hewett's "artificial gravity" or the thrust of an aerotow is removed, the glider can more easily be maneuvered in 3-dimensional space. While teathered to a car/tug, its movements are limited by the dynamics of the towline and strange things can happen... fast.
I think that this is the key question. Just how strong the weaklink should be. I'm talking about with the pro-tow bridle and aerotowing.
Towing makes re-launching so easy that not being dragged along the ground is certainly worth the three cents of material and the inconvenience of having to try it again... at least the pilot has another chance when the alternative might have a much worse outcome.
This is a very big issue at competitions.
We aren't Superman, nor are we perfect beings, and weather happens. A weaklink is but one piece of protection and works with other parts (sprogs, parachute, helmet, etc.) to accommodate some of our mistakes.
That's why we need to make sure they are actually used if they are the right thing to use. At the moment most competition pilots use "STRONG LINKS."
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Tracy Tillman - 2005/02/08 19:16:10 UTC
4592
Unfortunately, many hang glider pilots do not appreciate or understand the significant risks repeatedly taken by tug pilots and aerotow club or flight park operators, on behalf of hang glider pilots so that the hang glider pilots can have safe tows and have fun. Most tow pilots experience many more tows under a much wider variety of conditions, pilots, and equipment, and than even the some of the most experienced and advanced hang glider pilots. It is interesting to note (or so it seems) that when hang glider pilots try being tow pilots, the most don't last long.
The sailplane guys have been doing this for a long time, and there are many hang glider pilots and quite a few tug pilots who don't understand what the sailplane guys have learned over the years. It certainly would help if hang glider towing methods and training were standardized to the degree that they are in the sailplane world. Maybe the Sport Pilot regs will eventually help hang gliding in this regard. It helps a lot when a hang glider pilot gets a little training in sailplanes, and even more so if they experience sailplane towing at different locations and encounter very similar systems and techniques.
Both sailplanes and aerotowed hang gliders use properly-rated weaklinks at both ends for a very good reason. It is not primarily to prevent a lock out. It is a fallicy to think that weak links will reliably prevent a lock out. In engineering terms, the weaklink is not a robust design--it will not break consistently in a wide variety of conditions. If it is a lower-rated weak link, it may or may not break prior to or during a lock out--and it is also more likely to break in the heavy turbulence experienced by advanced pilots. Therefore, an advanced hang glider pilot may opt for a stronger weaklink, with some additional risk. Conversely, use of a weaker link in turbulance may cause a premature weaklink break, which can also entail some risk. Therefore, the use of a stronger weak link may be warranted.
If an advanced pilot wishes to use a stronger weak link, the degree of extra strength must be limited. Primarily, the use of a weak link is to save the tug pilot's behind, by preventing structural and/or control failure--and it should also help to prevent structural and/or control failure of the vehicle being towed. Secondarily, a lower-rated weaklink may or may not help to prevent a full lockout--just don't count on it.
The following recommendations are based on our experience over the last 10 years. We use 4-stroke powered Dragonflies, and our spring/early summer air is very turbulent.
Whether pro-tow or 3 point tow, we use and recommend a single stand loop of 130 lb weaklink for general pilots, which is not pre-tied, but uses the 4/5-loop-then-tie method for attachment. Pre-tying is less robust, meaning it does not break as consistently as the 4/5-loop-then-tie method. We use a single strand of 150 lb weaklink, again not pre-tied, for heavier, more advanced pilots in very turbulent air. We use a double loop of 130-lb weaklink for tandems, Scot Maue (big, VERY big), and at the other end for the tug. Also, the hang glider pilot should only use one weaklink, at the upper attach point in a 3 point bridle system, to prevent tucking should the bridle release at the low end and snag the ring. We have had excellent results using that system.
A tug pilot and/or aerotow operator has every right to inspect the use and quality of the weaklink used by a hang glider pilot, and has a duty to him/her self and the hang glider pilot to make sure that it is not too strong for its primary purpose. Concurrently, the hang glider pilot has a duty to understand and respect the well-founded concerns of the tow pilot and/or aerotow operator.
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Peter Birren - 2005/02/08 19:22:49 UTC
4593
Davis Straub - 2005/02/08 17:08:45 UTC
What does overtowing mean? I assume that it means the car is going too fast.
I wrote mostly of "general" weaklink use in towing, not aerotow-specific though I knew that's what you were asking specifically about. So, yes, overtowing is when either the driver mistakenly goes too fast OR does not slow down when weather conspires to create a sudden increase in tension.
I ask this question to point out that I so much can't imagine overtowing that I don't even know what you are talking about. In other words, this is not really a problem with aerotowing.
You're correct that it isn't a major problem with AT, but the potential exists for what can appear to be an overtow - say if the tug slows, towline goes slack, glider is mushed, tug regains speed... the quick application of force to the glider could approach "severe". This scenario is IMO what happened with Mike Haas at Cushing Field last year. His weaklink broke at a low altitude and he rolled off the stall.
Also, I can't imagine this "problem" being overcome by a weaklink, if they don't even work for lockouts.
They should work for lockouts, but due to the nature of the beast won't work until the tension point is hit, meaning the pilot is in full lockout and the glider is producing more than the weaklink strength in lifting power. Prior to getting to the point of breaking the weaklink, the pilot should have released.
Are you looking for a sure cure for lockouts? Simple: add a pitch limiting line from the glider's nose to the Apex release (closed bridle with release between bridle and towline). Each roll/yaw that takes a pilot away from the tow force direction produces a change in pitch between glider and towline. Limit that pitch and you'll eliminate full-blown lockouts.
It looks like weaklinks are a holdover from the old days.
While it may seem to be a holdover, there's still that nagging problem of piling in at launch. If this is the only immediate benefit of a weaklink, then it definitely has a place in the bridle/towline system.
I've blown aerotow and static line launches where the weaklink did its job perfectly each time. I'm happy to say that after each of these I walked away and was able to use the glider again (after some repairs). I also have gotten in near-lockout situations, recognized what was developing, and released before it got any worse. (But then I'm using a release that is totally independent of the tow force
...we need to determine how strong the weaklink should be just for this problem (blown launches).
One G or less should do it and is easy to figure out. Material is readily available and presently being used. More than this and it becomes a "strong link" that may not break during a nose-in, and it may not break when that full-blown lockout is achieved.
Rohan and others disagree. The weaklink is apparently no help in releasing from a lockout.
The weaklink will not prevent a lockout from happening, that's certain... and if you want one that will work quickly in a lockout, then it'll be too light for day-to-day towing in thermal conditions. If the pilot can recognize what's going on, it's possible to push out quickly and break the link... _IF_ the link is sized right. This is not an intuitive move and goes counter to panic thinking.
But why wait until fully locked out? Why not release before it gets that far? Is the 3-5 cent weaklink string too expensive? Is this one launch so critical that the pilot is willing to stake his life on it?
I've had problems when it is quite a bit more than a nuisance and I've been managing the tow force just fine, thank you.
Then I'd suspect the material or the knot used to tie it. You fly a rigid with aerodynamic control, which is faster than a flex wing, so I imagine you'd be doing OK. You've certainly been towing for quite some time and know what to expect. Do you rely on weaklinks at the site or have you found what works for you (tested) and carry your own?
Other pilots with plenty of towing experience may have grown complacent or are practicing poor form. You may be doing just fine, but that may only be fine in your mind. I'm not casting aspersions or accusing you of poor form, but stranger things have happened. If you're breaking weaklinks at nuisance times, something is wrong, either the weaklink, your setup or your towing style.
I think that this is the key question. Just how strong the weaklink should be. I'm talking about with the pro-tow bridle and aerotowing.
Where is your weaklink? Are you using an opening or closed pro-tow?
What are your expected tow forces? (aerotow produces 100-150 pounds)
How do you handle turbulence - smoothly or with quick inputs?
Do you like the idea of getting dragged in a blown launch?
How far into a lockout can you handle?
The Reel Pilots tested many different strings before settling on 130 or 150 pound test braided dacron kite string depending on pilot body weight. These translate to 235 and 260 pound breaking strengths in 4-strand setups, less than 1 G, and we haven't had an inadvertant weaklink break in a very long time, either static line or aerotowing. Any lighter and the string will break when encountering a strong thermal. At least that's been our experience.
This is a very big issue at competitions.
What is the big issue? Re-launching? Oh, the wasted time! Oh, the hassle! Oh, the embarrassment! These are sure preferrable to Oh Shit!
At the moment most competition pilots use "STRONG LINKS."
And Robin paid the price... is it worth it?
He also paid the price by using the wrong release in the wrong place.
- Peter
(yet another e-mail where I didn't mention the L-word
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Stuart Caruk - 2005/02/08 21:35:01 UTC
4594
I must be missing something. Do you actually make 4 or 5 loops with this single strand weaklink before it's tied? If so what is the ultimate
breaking strength of the link.
Curiously,
Stu
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William Olive - 2005/02/08 21:47:45 UTC
4595
The BIG issue at comps is; "where do I go in the line after I blow a launch?" Obviously the pilot wants to be back in the front of the line, whereas those who are waiting want him to go to the back.
Big problem, believe me.
Billo
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Gregg Ludwig - 2005/02/08 22:37:58 UTC
4596
Can we look forward to you offering sailplane ops at Cloud9, Michigan?
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Donnell Hewett - 2005/02/08 23:28:13 UTC
4597
Sorry, but I simply cannot stay out of this lively discussion on weaklinks.
Concerning that topic, I am firmly convinced of the following points:
1. Every towing system, without exception, contains a weaklink. It may be a string or mechanical device deliberately inserted into the towline, the towline itself, the release mechanism, the flying wires of the glider, the pilot's harness (when body towing), or some other component of the pilot-glider-tug system. But something eventually is going to be the first thing to break. That thing is the weaklink.
2. Of all of these options, the ONLY PROVEN ACCEPTABLY SAFE weaklink is a string deliberately inserted into the towline which consistently breaks at a known and specified tension.
3. The sole purpose and function of this weaklink is to limit the towline tension to a manageable level, i.e. a level such that the pilot can still maintain control of the aircraft in the event that the weaklink breaks.
4. The appropriate strength of a weaklink depends upon pilot skill. A skillful pilot can maintain control when a stronger weaklink breaks whereas a less skillful pilot cannot. As a general rule, a beginning pilot should limit his towline tension to 1/2-g and an experienced pilot to 1-g. Only highly experienced pilots qualified to perform aerobatics while on tow should use a 2-g or stronger weaklink while being pulled forward (such as when aerotowing).
5. The appropriate strength of a weaklink depends upon the type of towing system used. Different strength weaklinks should be used for foot-launched ground towing, platform towing, aerotowing, boat towing, etc. As a general rule, forward pulling systems such as aerotowing, foot-launch ground towing, etc. should use 1-g weaklinks or less. Consistently downward pulling systems such as platform launch can go as high as 2-gs.
6. The appropriate strength of a weaklink does not depend upon weather conditions or the flight attitude of the glider (turbulence, wind gradient, lockouts, etc.). It is impossible to design a weaklink to release the pilot when he looses flight control because there is no correlation between towline tension and flight control. (A pilot may be in perfect control under high tension but out of control under low tension.) A weak link can only be designed to release the glider under the worst possible conditions before the towing forces exceed the limits of safe recovery when the weaklink breaks.
7. The appropriate strength of a weaklink should always be tested on the ground, not in the air. For example, if a weaklink is tested on the ground to consistently break at 1-g, then you can be certain it will do the same thing in flight. Therefore, if this ground-tested weaklink keeps breaking inconveniently while aerotowing, you can be certain that the problem is not the strength of the weaklink. The problem is with something else concerning the towing system, the flying technique, or the flight conditions. For example, if there is enough thermal activity that the tug and glider enter different air causing the towline to go slack, then there is also sufficient difference in the air to cause the towline to tighten and the tension to increase rapidly. Unless there is sufficient stretch in the towline to allow a skilled pilot time to compensate for this rapid increase in tension, it will quickly increase beyond the weaklink breaking point even while the pilot is in perfect control. If the problem is a lack of stretch of towline, the system needs changing. If the problem is flying technique, the pilot needs more training. If the problem is excessive air turbulence, flight operations need to be suspended. Simply switching to a stronger weaklink does not make this situation better, it simply makes things more dangerous when that weaklink does not break and when (not if) it does break.
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Larry West - 2005/02/08 23:34:51 UTC
4598
So, how many pounds is a 1g or 2g weaklink built to fail at?
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Tracy Tillman - 2005/02/09 01:01:21 UTC
4599
Absolutely. we are in the process of getting a second Maule as a tug, as well as a Grob 103.
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Tracy Tillman - 2005/02/09 01:07:04 UTC
4600
Thanks Don, Tracy
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Tracy Tillman - 2005/02/09 01:25:26 UTC
4601
Hi Stu. No, the standard method of the 4/5 loop-then-tie system is to not pre-tie the weaklink, but to simply wrap a 10" length of weaklink around the long (upper) bridle loop 4 or 5 times, leaving enough length for a single strand loop to be created, tying a simple overhand knot, placing the knot in the center of the other loops, and tightening so that the knot is under the other string loops that are wrapped around the bridle loop. It provides a single loop weaklink with 130 lb x 2 = 260 lb loop that is about 1 to 1 1/2 inches long, without a knot in the system that cuts into the line under tension. I know that a drawing would help to clarify the method. It takes a few more seconds and a few extra inches of weaklink to tie, but is much more reliable. A few aerotow gurus know about this style of weaklink, but unfortunately, this method is not generally known because the high-volume production flight parks do not teach and use it due to the extra time it takes to tie up this style of weaklink. That's really unfortunate, because it really does work better.
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William Olive - 2005/02/09 02:50:06 UTC
4602
Tracy
A photo sequence would be even better, how about posting one?
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Peter Birren - 2005/02/09 03:30:56 UTC
4603
William Olive - 2005/02/08 21:47:45 UTC
Big problem, believe me.
... and no arrangement will suit all the pilots. The guy who released early ought not be penalized for making a safe decision. Recovery time should be permitted and the pilot allowed to enter the queue when fully ready. The interruption to others in the line is far less than if the pilot had crashed, no matter what the outcome.
Argh! Promised to stay out of competition talk. Oh well.
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Peter Birren - 2005/02/09 04:03:43 UTC
4604
1G is the all-up combined weight of glider and pilot in flying form.
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Larry West - 2005/02/09 04:45:38 UTC
4605
Larry West. Personal
So, I calculate that my total system weight (Discus 160@65 pounds, me at 215 and my harness/chute/water/bags@23 pounds) is 303, So my weaklink should break at 500 or 600 lbs?
Holy cow!!
Last week, I was towing with one strand of #24 mason line and climbing at 800fpm on a scooter tow. I need to check these week links to find out where they really would let go.
Thanks for the info!
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Weaklinks and aerotowing (ONLY)
Davis Straub - 2005/02/09 06:13:39 UTC
4606
A few statements to try to pin this down.
1. Weaklinks do nothing for us with regard to lockouts. Neither prevention nor releasing (breaking) when fully locked out. Your release needs to be activated when in this situation.
You should also now be able to understand that the towline forces in a lockout need not be very high. They only need to be sufficiently high to cancel out the effect of a maximum pilot weight shift/yaw in order to cause a continuation and worsening of the situation. Lockouts can and do both occur and continue without ever exceeding normal tow tensions. As a result A WEAK LINK OFFERS LITTLE PROTECTION FROM A LOCKOUT.
The biggest fallacy in towing is that a weak link will protect you from a lockout. For ground towing this is wrong. The tow line force required to break the weak link is roughly 2-3 times the force required to sustain a lockout - I have seen this demonstrated on numerous occasions. As a result you could potentially continue a lockout all the way to the ground without ever breaking the weak link. If you have ever seen a childs kite lock out and arc into the ground you should intuitively understand this.
2. Weaklinks are only of value to the hang glider pilot if you come off the cart prematurely and hit the ground hard with your glider and dig in. They are supposed to break then.
3. The tug pilot has a weaklink and it is supposed to break under the load of you plowing in. It is also supposed to break under the load of catching the tow rope on a tree or fence or whatever.
4. The hang glider pilot's weaklink is supposed to be weaker than the tug pilot's weaklink to give the tug pilot an extra margin of safety.
5. There are situations where breaking a weaklink can be dangerous to the hang glider pilot, say towing east out of Quest and just coming up to the trees. Or towing downwind.
6. 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):
1/2 G (inexperienced pilot): 68 kg (150 lbs)
1 G (experienced pilot): 136 kg (300 lbs)
2 G (very experienced aerobatic pilot): 270 kg (600 lbs)
Looks like we have a rather wide range here.
At Quest and Wallaby 130 pound test line in a loop with a fisherman's knot is used. That is two strands minus the weakness due to the knot (225 lbs). If I put it on my Pro-Tow, then the tension on it is reduced by the cosine of the angle (results is =>300 lbs).
I've been flying with two of these (four strands) for the last year (and never replaced the "strong links") so approximately 600 lbs.
It appears that Tracy is using a loop of 130 lbs test line just like Wallaby and Quest with some kind of knot, which I can't figure out. They did extensive tests at the Worlds and by far the fisherman knots were the most consistent and least reduction.
So I will have to find out just how strong the weaklinks are on the Dragonflies at Quest.
Bill Moyes lost eleven spectra ropes in the first two days of the Worlds because the pilot's weaklink was stronger than the plane's weaklink. I had heard that the plane's weaklink was 115-135 pounds. The ones on the Dragonfly were on V-bridles at the end of the V-bridle, and the ones on trikes were on three ring circuses.
End result: A very wide range of possible weak link values here depending on pilot skills and weight.
Competition:
Pilots need to be able to go to the front of the line (if they are ready to launch) if they have a weaklink break. Otherwise you'll have "strong links."
Sailplane experience
I have it. I don't see any reason to get it for hang glider aerotowing.
What don't I discuss here: The tow line type - spectra or poly, the length of the tow line, the type of release mechanism and bridle.
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Weaklinks and aerotowing (ONLY)
Oddvar Kallhovd - 2005/02/09 13:10:01 UTC
4608
Here you refer to Don's words, I think he speak in general since there is no specific (according to Skyting) for aerotow. We can conclude with still "a very wide range of possible weaklink values" if we limit our discussion to weaklinks only. It is never going to end. Here is a part of section 7 in Don's reply:
The problem is with something else...
A 60 m spectra rope don't stretch very much. I can imagine the frustration..., with hardly no stretch at all it is certain that weaklinks are going to break at all kinds of situations - from a tug pilots point of view, remember he only feels, no see. I would guess it feels rather dramatic sometimes breaking a weaklink, others just snatch off like nothing. I know this physical phenomenon from two lockouts of my self, static and aerotow, and the reason which provoked them, but also from 10-12000 hours "piloting" cranes; by i.e. handling/lifting of stuck loads or loads frozen to the ground during winter time.
I think the towing community needs to go for a standard here in regard to length and minimum stretch. If I'm allowed to feel and think I would say 5-10 m stretch in rope before weaklink break. If this turns out to improve, we may find ourself towing with 60 kg weaklinks before soon..., remember it's the stretch not the strength.
Pilots need to be able to go to the front of the line (if they are ready to launch) if they have a weaklink break. Otherwise you'll have "strong links."
Rigth, it's the communitys problem if a weaklink break for a pilot - seriously, no matter the reality - we should have equipment handling "flyable" conditions. I think a weaklink break more or less depending on bad luck, even if the pilot seems to blaim himself.
Sailplane experience...
I see this. May be not for you since you already got this experience, but I see many pilots which I think need to focus on the tug and stay focused, sometimes even not blinking their eyes when a situation feels unstable. When learning (read: learning) to fly a sailplain you more or less keep your eyes on the tug, because it's nothing more to look at, and it's nothing more you need or want to look at! In a hangglider theres just too much to look at for an advanced pilot. I think a few tows in a sailplain may give this "message" to the hg-pilots. Keep focused onto the tug every single second - if someone not learn this they should try some sort of eyeflaps reminding them; every time they lower or move their head more than an inch they get slapped on their chin. If this don't work - leave towing to the pilots.
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Weaklinks and aerotowing (ONLY)
Tracy Tillman - 2005/02/09 13:28:32 UTC
4609
Very good comments from Davis, but I must respectfully address two issues:
Davis Straub - 2005/02/09 06:15:33 UTC
It appears that Tracy is using a loop of 130 lbs test line just like Wallaby and Quest with some kind of knot, which I can't figure out.
Hi. Next time you are there, ask Russ or Campbell at Quest to show you the knot we are using. It's been around for a long time, but not widely known or used because of the extra time it takes to tie and the extra material used. Because it is a better method that provides a more consistent break than a pre-tied fishman's knot, advanced pilots do not need to over-do it and go to a double loop (4 strands). If a comp pilot is using a double loop (4 strands), then their weaklink is not weaker and perhaps even stronger than the one at the tug. It is common for tugs to have 4 strands (double loop) of 130 line, which is 520 lbs.
Sailplane experience
As tug and tandem pilots, it is clear to us that it is helpful for aerotowing hang glider pilots to have a bit of sailplane experience. It is understandable that hang glider pilots without significant tug pilot and/or tandem training experience may not understand why that is so.
*
Bill Finn - 2005/02/09 15:25:42 UTC
4611
Tracy,
Is there a drawing of this knot on a web site anywhere? If not (no pun), any chance you can get one on your web site?
billyjoe1937
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Bill Finn - 2005/02/09 15:55:22 UTC
4612
Billo...all competition pilots,
I can imagine how getting "caught up" in the competitive spirit can adversely influence decision making. Winning, even at any cost, can be intoxicating...maybe the higher the cost, the more intoxicating? But, isn't allowing one's self to make, what would ordinarilly be considered to be a bad/foolish/unsafe decision, just because one is competing, a little like having the tail wag the dog? "This competition thing is so important to me that I'll allow it to cloud my good judgement."
I know that ideally, it's important to minimize subjectivity in any kind of competition and to focus on winning/losing. But, why can't we factor into the scoring of HG competition some sort of safety index? You know, if you fly recklessly (needs to be defined), you get some kind of scoring deduction(s). Even if you "win", you lose. If you want to gain an advantage over others by acting foolishly, you get penalized for it.
Would that idea take too much away from the competition "culture"?
*
Peter Birren - 2005/02/09 16:25:54 UTC
4614
500 pounds is stronger than the towline we use for static line (425# for new 3/16 braided poly). My all-up weight is (175 me + 25 harness/
instruments + 75 glider) = 275... the weaklinks are rated at 235, so it's less than 1G. With this I've climbed at 1500fpm on a static tow.
Don's mention of 2G weaklinks is for different situations. "Only highly experienced pilots qualified to perform aerobatics while on tow should use a 2-g or stronger weaklink while being pulled forward (such as when aerotowing)." ... "Consistently downward pulling systems such as platform launch can go as high as 2-gs."
*
Weaklinks and aerotowing (ONLY)
Peter Birren - 2005/02/09 16:25:55 UTC
4615
Hi, Tracy.
Testing weaklinks for our static tow use, a continuous loop (with grapevine knot) of 130# line broke consistently at 235 lbs +/- ~5 lbs. This was with the line around 1/4" rapid links. Using smaller diameter 1/8" rapid links the string would break about 10-15 lbs less. We did not attempt the setups you use, tied onto the steel link v/s looped over it as we do, but I can't imagine the breaking strength to be more than double.
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Larry West - 2005/02/09 16:59:01 UTC
4616
ok,
so a 300lb will be recommended for scooter, and I should make some 400 pounders for the platform rig we're getting back up to speed on.
I can use my 300s on Aero too, ya think?
Thanks again for all this info. I'm accumulating quite a brain load here.
hope to get to use it soon
The guy with the platform rig has it in his hanger, and hasn't touched it in 2 years, so it may need some work. Has new line on it, but no other maintenance has been done on it.
I won't get on it until I see it work smoothly 5 or 6 times.
The scooter however, I REALLY like.
I'm getting mixed feelings about dollys on aero'. Lots of chances for failure there.
*
Donnell Hewett - 2005/02/09 18:02:20 UTC
4617
Wow, I guess I really did wade in.
Larry West calculated that he was scooter tow launching (I assume foot-launching) at 65 lb glider + 215 lb pilot + 303 lb equipment 583 lb takeoff weight, so he would be using a 1-g weaklink designed to break at 583 lb. And then he said, "Holy Cow!" I agree, "Holy Cow, I would love to watch a 215 lb person foot launch with a 583 lb takeoff weight."
And finally, Larry concluded:
so a 300lb will be recommended for scooter, and I should make some 400 pounders for the plat
form rig we're getting back up to speed on. I can use my 300s on Aero too, ya think?
Let me say, "Yep. Assuming you and your glider and equipment weigh about 300 lbs, you can use the 300s for everything, even the platform launch." The reason is that many platform launches pay out the line so fast during the early part of the flight that the line is pulling more forward than downward. Under these conditions the 400-pounder is starting to push over the limit of safety. Only if you are paying line out slowly enough so that the glider is always primarily over the platform should you use a stronger weak link. So the general rule of safety is to tow with a weaklink between1/2-g and 1-g. In your case, I would recommend something that consistently breaks around 270 lbs.
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Weaklinks and aerotowing (ONLY)
Tracy Tillman - 2005/02/09 18:15:59 UTC
4619
Hi. It's great that you did that testing. I know different vendors, different string construction/material, different tying can affect that. Any chance that you got data with the knot eliminated (which is what we do)? Thanks, Tracy
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Jim Gaar - 2005/02/09 18:21:05 UTC
4620
I would stay with 130# braided dacron kite string for AT. We use it at our Flight Park for all solo tows. 8 inch piece tied with grapevine knots does it's job consistantly. I've got the links for ordering some if you want them.
I use an "open" V bridle with a pull lanyard (ah-lah LMFP) and hook in at 230ish pounds. My total package is therefore 280ish pounds (weaklink breaks at 260ish).
I've used this line to "chase the ace" and in very rowdy bullet thermal conditions and have had no issues. Yes I have busted one but it was from too many tows on the same weaklink DOH! I have yet to get into a situation that would have called for a break as I'm an early release guy, but also I have tested the line I use and it breaks consistently as Peter has stated.
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Jim Gaar - 2005/02/09 18:24:38 UTC
4621
Oh yeah. We are towing with 250 feet of 3/16 poly...
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William Olive - 2005/02/09 21:36:05 UTC
4623
Bill
The overhand knot is also known as the granny knot or thumb knot. It is the simplest of all knots and easy to tie, which is important if you are making several hundred weaklinks a day It does not slip, but is a lot weaker than the parent material. This isn't important if you "bury" the knot (perhaps need a pic to show what I mean) on the ring. It is similar to the reef knot, but the reef knot slips and therefore is not suited to making weak links. You probably used this knot to join the ends of a loop of string many times, and never thought about it. I can show how we do it with pics if you wish.
BTW, prior to Gulgong this year, Shane Duncan and I tested a number of string/knot combinations on the Airborne strain gauge. We ended up using #8 brickies twine tied in a loop with an overhand knot then put between two rings as four strands. This broke consistently (tested) at 90kg. We had hundreds of tows during Gulgong with very few (<10) weak link breaks. We were using 4mm poly ropes 80m long, and never broke a rope, which shows our weak links were not over strength, as 4mm poly rope is almost a weak link in itself. We use the same weak link material with six strands at the tug end.
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Weaklinks and aerotowing (ONLY)
Peter Birren - 2005/02/10 00:05:40 UTC
4627
No, Tracy, we didn't go there... didn't think to do it. We decided that each pilot in the club would tie their own weaklinks so the chore doesn't fall on one person. So keeping it simple we found the material that would fit our needs.
130# and 150# braided dacron kite string from Catch the Wind Kites - 800-227-7878 - costs about $16.00 per 1000' roll and very consistent. The whole roll is cut to 20" pieces (apex release (static or aero) can use any length weaklink).
For our static line (and my aerotowing) use, the 130# line is for the average-size pilot; 150# is for the bigger boys. 4-strand weaklink gets placed between towline and bridle for aero or static; 2-strand is for those who use the Opening Bridle for aero.
Are you using a clove hitch with half-hitch lockers?
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Gregg Ludwig - 2005/02/10 03:22:31 UTC
4629
For our static line (and my aerotowing) use, the 130# line is for the average-size pilot; 150# is for the bigger boys. 4-strand weaklink gets placed between towline and bridle for aero or static; 2-strand is for those who use the Opening Bridle for aero.
Peter-
Our club uses a stronger weaklink for winch towing as compared to aerotowing. Your use of a 4 strand weaklink for aerotowing would be considered by most to be too strong.
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Weaklinks and aerotowing (ONLY)
Gregg Ludwig - 2005/02/10 03:34:47 UTC
4630
A 4 strand weaklink is about double the strength of a 2 strand weaklink...
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Weaklinks and aerotowing (ONLY)
Tracy Tillman - 2005/02/10 04:12:38 UTC
4632
Uh-no. Per the suggestion and request of quite a number of folks, I'll be posting some pics and a description. Our 914 powered Dragonfly with the Prince Prop climbs like a mother-fxxx... under full power. We find pre-tied 130 lb line weaklinks to inconsistently but often break in turbulence, whereas the 4/5 wrap-then-tie 130 lb line does not, because there is no knot under tension--just clean string.
It's a relatively old and KISS type of weaklink design. We learned it from the originators of Quest, and we've been using it here since Day 1 of the Draachen Fliegen Soaring Club. It's amazing that it seems like hardly anyone else knows about it.
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Weaklinks and aerotowing (ONLY)
Bill Finn - 2005/02/10 05:02:53 UTC
4634
I can't wait to see this thing.
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Peter Birren - 2005/02/10 15:43:29 UTC
4638
Yes, my 4-strand, 235# weaklink would be too strong if used at the keel for an opening bridle. But I'm placing the weaklink at the end of the towline, through the Linknife and on a rapid link "pulley" which floats on the closed bridle. In this arrangement, the 4-strand takes the full load of the tow v/s 1/2 that tension at the keel.
Bad news - good news:
Bad news is that I blew an aero' launch rather spectacularly (some might add that it's bad news I survived, but I digress).Good news is that this weaklink arrangement broke immediately and prevented the digging of a 75 yard furrow with my face (some might add that it looks like I did do it).
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Larry West - 2005/02/12 16:19:35 UTC
4678
Larry West. Personal
It has been pointed to me that the Discus is actually73 pounds.
Man, I'm going to need a beefy weaklink.
I'd like to dredge this old discussion back up to the surface 'cause the AT culture is still hopelessly clueless on this topic and there are some major lumps which need ironing out.
Primarily I want to address some issues within Donnell's post of 2005/02/08 23:28:13 UTC (#4597) with a focus on the way things are conducted at the high volume Dragonfly parks in this quarter of the world.
While this piece is well written and does a fair number on the perpetual myth that weak links have something to do with lockout protection, I see some major inconsistencies and conflicts with other articles and the ways things happen at the runways.
For starters - The place I finally found religion is:
It took about two years for me to cleanse my mind of all the indoctrination with which it had been poisoned before but when the bulb finally hit full intensity it was blinding.
Summary:
The sole purpose of the weak link is to break before the plane does.
- PERIOD
Donnell correctly states that:
The appropriate strength of a weaklink does not depend upon weather conditions or the flight attitude of the glider (turbulence, wind gradient, lockouts, etc.). It is impossible to design a weaklink to release the pilot when he looses flight control because there is no correlation between towline tension and flight control. (A pilot may be in perfect control under high tension but out of control under low tension.)
but immediately goes on to say:
A weak link can only be designed to release the glider under the worst possible conditions before the towing forces exceed the limits of safe recovery when the weaklink breaks.
Am I the only one who sees those two snippets as mutually exclusive?
For many years I subjected myself to the tyranny of the conventional "wisdom" that the only acceptable weak link for a solo glider of any weight is a single loop of 130 pound Greenspot at the end of a bridle.
I hook up at about 320 pounds and with that junk at the top end of my two point bridle I get AT BEST 0.76 Gs. (At worst I get 0.39 Gs but let's ignore that for the moment.)
The last time I remember being locked out (three years ago - at altitude) I was on my ear - thirty degrees beyond the placarded roll limit of my glider - before my brain finished connecting to my hand. And the little string was still doing just fine.
Karen hooks up at 200 pounds and - of course - uses that same weak link (which she's never broken) so she's limited to a max of 1.22 Gs. I'm thinking she could win an aerobatics competition without ever hitting her release.
Practically speaking, I don't believe that - given enough air - there has ever been an incident of any pilot of any skill level having a problem recovering from any attitude achievable while connected to a tug through a weak link of any strength.
For the purpose of this discussion we're only hurting and killing AT people who are too low to be able to recover and weak links have never been issues in these scenarios.
I hope we can all agree that there's no way freakin' way that those situations can be safely and reliably defused by weak links. Those problems have to be mitigated by the development of flying judgment and skill, use of reliable and easily actuated releases at both ends of the tow line, liberal use of wind streamers, and correlation of conditions to skill level.
So I don't agree that it is appropriate to scale weak link rating to pilot skill level. This seems to carry the false assumption that the weaker the link the safer the flight and - trust me - there are plenty of situations in which the last place you want to find yourself is off tow. I can think of at least two people who were killed because they really needed line tension and couldn't get it and one who is alive and well because he did.
The way things are almost universally practiced now is... The smaller you are - the higher G rating you get. Brilliant.
And it gets even worse 'cause the bigger you are the faster you degrade a marginal weak link. Therefore Karen may start out with a 1.22 G weak link and end up with the same at half a mile up. That same weak link - 0.76 Gs for me when I put it on the bridle - starts breaking fibers as soon as the tug starts moving and can fail before I get to a hundred feet.
The FAA - with respect to sailplane towing - specifies a 0.8 to 2.0 G weak link range. I presume they do this to define limits for safety. Three observations:
- They don't correlate anything inside this range to pilot skill level.
- It appears that they consider anything under 0.8 Gs to be dangerous. So do I.
- If these are indeed reasonable lower and upper safety limits and G rating has no correlation to pilot skill then the safest number - the one or which EVERYBODY should be shooting - is the one in the middle - 1.4 Gs.
Also, I'm not buying that because the normal tension involved in forward is less than that involved in downward pulling towing that you scale the weak links accordingly. If anything - correct me if I'm wrong - it should be = the opposite.
In aerotowing you're not much worried about excess forward pulling tension 'cause that "problem" is gonna take care of itself pretty fast by translating to speed and altitude. The situation in which it's gonna be desirable to lose tension real quick is when the glider has rolled so far away from the tug that it ain't coming back and that is not a forward pulling scenario.
And since aerotowing is speed controlled the tension starts going up fast when you start getting out of kilter. And - trust me - you don't want to be popping off tow every time you have to plow through a little turbulence.
Conversely, since most downward pulling towing is tension controlled, you can generally get away with a lower rated weak link 'cause normally it's impossible to get much of a deviation no matter what you do.
And if the FAA has anything to say with respect to weak link safety ranges being different for aero and winch towing - I can't find it.
Ridgely has pulled something on the order of forty thousand tows over the course of its ten seasons. Let's be REAL generous and say that they're only breaking weak links at the rate of one per twenty flights. That's two thousand pops. The percentage of those that were desired and necessary for the safety of the flight is ZERO. So what do we learn from these numbers?
Of all of these options, the ONLY PROVEN ACCEPTABLY SAFE weaklink is a string deliberately inserted into the towline which consistently breaks at a known and specified tension.
I'd like to get some comments on these points 'cause the AT system is totally broken on this issue. I think the first step to fixing it is to get the USHPA to amend its rules by specifying a minimum allowable weak link rating which is in accordance with that required by the FAA.
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Gregg Ludwig - 2008/10/07 22:08:56 UTC
6671
Tad-
I find your latest post quite interesting. I must say it has taken me sometime to get used to or accept your writing style but you make some valid points. When you refer to "ushpa" you are actually referring to me, Chair of the ushpa Tow Committee. Our next Tow Committee meeting will be at Chattanooga, TN 23-25 October. Can you attend?
Gregg Ludwig
ushpa Tow Committee Chair
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Tracy Tillman - 2008/10/07 23:38:15 UTC
6672
Just FYI for comparison. It is important to understand that the FAA would not have been thinking about the use of V-bridles. and relative placement of weaklinks. Regards, Tracy T.
USHPA:
C - WEAK LINKS
Requirements: 1) Weak links must be used on every flight. 2) An aerotowing weak link must have breaking strength no more than 100% of the flight ensemble (pilot and glider) weight as tested in the configuration to be used.
8) The tug should have a V bridle with a release at one end and a weak link at the other when applicable.
4) The tug weak link can save the tug pilot if the towed pilot locks out or the towline entangles on ground objects. This weak link should be stronger than the glider end weak link so the glider pilot isn't normally left with the towline.
FAA:
FAR Part 91.309
(i) A safety link is installed at the point of attachment of the towline to the glider with a breaking strength not less than 80 percent of the maximum certificated operating weight of the glider and not greater than twice this operating weight.
(ii) A safety link is installed at the point of attachment of the towline to the towing aircraft with a breaking strength greater, but not more than 25 percent greater, than that of the safety link at the towed glider end of the towline and not greater than twice the maximum certificated operating weight of the glider;
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Tad Eareckson - 2008/10/09 14:44:12 UTC
6680
Damn. It appears that the author of the post I was addressing is no longer a member of this forum. I had really hoped to get his comments.
Gregg,
Thanks very much for yours and honoring me with the invitation. I'm a bit queasy about the travel and expense but am seriously considering it. Perhaps you could send me some more details at TadErcksn same ISP as yours.
Tracy,
Thanks also for your comments and the references.
But the bridles and weak link placements are not relevant to this discussion. We're talking Gs and tow line tension. All we're concerned with is limiting that tension such that there's no way that either plane will break as a result thereof. Sailplanes break at around the same G ballpark as hang gliders so we're also good with the 2.0 G upper figure.
Minor problem with 91.309... If you go to the max with (i) it's impossible to comply with (ii).
With respect to "USHPA:"...
MAJOR problem with 8.
Towing Aloft" - Page 349...
I witnessed a tug pilot descend low over trees. His towline hit the trees and caught. His weak link broke but the bridle whipped around the towline and held it fast. The pilot was saved by the fact that the towline broke!
SO WHY THE HELL HAVEN'T WE FIGURED OUT THAT WE NEED WEAK LINKS AT -BOTH-ENDS OF THE BRIDLE?!
And how 'bout sticking one on the front end of the towline too, just for laughs.
Last year I wrote and recommended a revision which briefly got a little attention but is still over there in the "Files" section gathering dust.
The 2004/07/30 version specifies twice the G rating that you quote above.
I can find no trace of any variation of this document at the USHPA site but here's what it says in the current (2008/03) version of:
Standard Operating Procedure 12-02
Pilot Proficiency System
2.10 USHPA Hang Gliding Aerotow Ratings
B. USHPA Aero Vehicle Requirements
5. A weak link must be placed at both ends of the tow line. The weak link at the glider end must have a breaking strength that will break before the towline tension exceeds twice the weight of the hang glider pilot and glider combination. The weak link at the tow plane end of the towline should break with a towline tension approximately 100lbs. greater than the glider end.
(It also says:
6. A release must be placed at the hang glider end of the tow line within easy reach of the pilot. This release shall be operational with zero tow line force up to twice the rated breaking strength of the weak link.
and - as I've indicated before - we've managed to make a total hash out of that one too, but that's a bit OT.)
So we've got contradictory directives. I'm going with the USHPA versions 'cause it's righter and - besides - I don't want Karen to lose her rating because of her flagrant, continuous, and ongoing violation of the other one.
The people I DO want to see grounded are the bozos who show up at the flight line with sub 0.8 G weak links, relaunch in front of me because of "no fault" breaks, chew up so much of the afternoon's soaring window that I don't get to fly, and raise the price of my lift ticket 'cause I have to subsidize that crap.
And - of course - there's no shortage of benighted flight park operators, tug pilots, and competition meet directors who force people to tow on the ragged edge of sustainability with dangerously understrength weak links.
... You're trying to convince people to be less safe. I don't want to be on the other end of the rope when someone listening to this drivel smashes in.
I've heard it a million times before from comp pilots insisting on towing with even doubled up weaklinks (some want no weaklink). I tell them the same thing I'm telling you... suck it up. You're not the only one on the line. I didn't ask to be a test pilot. I can live with your inconvenience.
...
And here's what it says in AerotowGuidelines.pdf:
USHGA AEROTOWING GUIDELINES
I - EQUIPMENT
C - WEAK LINKS
Discussion:
5) Inadvertent weak link breaks at low altitude can lead to accidents.
Yeah. I've heard about, seen, and had them. Points that Tug Pilot seems to have missed - aside from this and the SOPs - are that the Dragonfly is equipped with a:
a) release actuation lever; and
b) weak link of its own of a strength of his choosing (which happens to be a doubled loop of Greenspot on the bridle which is permanently installed to deal with the tandems he frequently tows).
I suspect that carbon monoxide may be playing a part here.
Note that it seems that the pilots with the higher levels of experience and skill - while apparently not being familiar enough with the SOPs to understand their rights and not understanding what the function of a weak link is supposed to be - instinctively realize that the junk they're being compelled to use is doing more harm than good.
Referring back to the 40000:2000 ratio... What that means - to answer my own question - is that if a weak link had NEVER been used at either end of the tow line, if there was nothing but two thousand pound Spectra between tug and glider, they would have been running a SAFER, better, cheaper, more efficient operation.
Less gas, less wear and tear on the Dragonflies (cracks were discovered in the fuselages of both this season), longer Rotax overhaul intervals, shorter launch lines, better competitions and fly-ins, fewer broken downtubes and skinned knees, cheaper lift tickets, fewer wasted trips to the Eastern Shore, higher flights, and more airtime for everyone.
And if everybody had been using 1.4 G weak links it's almost certain that none of them would have broken and we'd have reaped all the same benefits.
One more thing - if we do the monkey/typewriter thing long enough - eventually somebody is going to die because a needless weak link break will put him in a really bad position that he would not otherwise have experienced.
To: Davis Straub; Tow Group
Cc: Rohan Holtkamp; Paris Williams
Weak links are there to protect the equipment not the glider pilot. Anyone who believes otherwise is setting them selves up for disaster. The pilot activating his or her releases is their way to save themselves. A perfect analogy is the circuit breaker in your home, it is there to protect the wire not what you plug into the wall socket. If anyone does not believe me they can plug their car retrieve 2-way radio into the wall socket and watch it go up in flames with the circuit breaker cumfortably remaining in the on position (I hope no one really tries this .
Bull's-eye.
The weak link is only there to keep the glider from breaking up in the air - not to keep it from hitting the ground. If you start dumbing it down to try to do the job you and your release are supposed to be doing you're just making the tow more dangerous.
Sailplanes are a lot easier to control than are hang gliders. Therefore one can predict that there will be less fluctuation in tow tension. Therefore - in my opinion - we've got no business pushing close to that 0.8 G lower limit.
If the points some of these other folk and I are trying to get across and the current USHPA SOPs are valid then the following contains misleading and incorrect elements:
Skyting Criteria
GROUP 2 - Safe Transition
07: Infallible Weak Link
The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation. (There is always the possibility something unexpected can happen. Breaking point should be appropriate for the weight and experience of the pilot, not to exceed 1G - sum of all towed parts.)
My recommended revision:
One or more weak links must be configured to ensure that the towline tension can never exceed 140 percent of the hookup weight of the glider, plus or minus 60 percent.
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Tad Eareckson - 2008/10/09 15:14:52 UTC
6681
That was a bit ambiguous. Let's make it:
One or more weak links must be configured to ensure that the towline tension can never exceed between 80 and 200 but preferably 140 percent of the hookup weight of the glider.
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Stuart Caruk - 2008/10/11 20:58:41 UTC
6684
For aerotow, I think this is absolutely correct. The concern of the FAA is the aircraft not the towed object.
For years I used to tow aerial advertising banners and they required a special waiver from the FAA. The FAA always wanted to ensure 2 things:
1) that the banner would not inadvertently be dropped over a major city which could create problems (drifting down into freeway traffic could be a problem) and that
2) The airplane was protected from overloads. Virtually all our banner launches incorporated the aerial pickup method where we snag a loop of rope held between 2 poles with a grappling hook attached to the end of a cable, which is in turn attached to a weak link and a tow ring that goes into a glider tow release on the tail of the aircraft. Every once in an odd while the tow hook would nail something solid during the pickup and break the weaklink. This is of course preferable to ripping the tail off the aircraft. We had a weaklink on the banner end as well that protects the pilot from overloads (allegedly) from something like picking up the banner on the nose gear, or main gear (definitely an attention getter).
Similarly when we aero towed gliders the loads were less, but protection of the aircraft was paramount. It's very easy for a pilot in a glider to put the pilot of a tow plane in a precarious position. The solution is almost always to give said pilot the rope. Having been on the glider end enough times, I'd say that coming off tow down low is a non event. In a paraglider it's either a non event or an exciting one depending on the attitude at the release. In a hang glider, it can create major issues.
I suspect the FAA has no idea what the ramifications of pinning off a tow at high or low tensions really are, however.
*
Donnell Hewett - 2008/10/14 00:49:34 UTC
6686
tadercksn,
Since I have not had time during the last week to respond to your request for comments on the topic of weeklinks until now, I would like to do so at this time. In order to save time and space, I will insert my comments in blue after the various quotes from your email in black.
For starters - The place I finally found religion is:
I tried to access this web site but without success, so I am not quite sure about what religion you found.
It took about two years for me to cleanse my mind of all the indoctrination with which it had been poisoned before but when the bulb finally hit full intensity it was blinding.
I am sorry it took so long, but I'm glad the bulb finally lit up.
Summary:
The sole purpose of the weak link is to break before the plane does.
- PERIOD
I respectfully disagree with you here. Any airworthy aircraft can withstand more than 4 g's before breaking up. Therefore, a weak link of 3 or more g's would easily break before the plane does. But a 3 or 4 g weak link would be extremely dangerous even if it did prevent both plane and glider from breaking.
However, you are absolutely correct in recognizing that there is always a weak link somewhere in any and every towing system. It may be the tow plane, the glider, the tow rope, or some other component of the complete system. And you are certainly correct in realizing that you don't want either the plane or the glider to be the weak link in actual practice. Therefore, one of the important purposes of a weak link is certainly for it to break before either of the aircrafts break. But it is not the sole purpose.
In my opinion, the sole purpose of a weak link is "to allow the aircraft to recover safely when the weak link does break". Obviously, if the aircraft is the weak link, recovery is impossible. But even if the aircraft does not break, recovery may still be extremely dangerous.
In the early days of towing hang gliders, the mantra was "Never use a weak link because it always breaks at the worst possible time and when it does break it only increases the danger of the situation." They tried to beaf everything up so that nothing would break. But something would always break when the towing forces became strong enough. And when that something broke (even if it was not the glider), someone would die. Imagine a 4 g towline pulling forward on a the center-of-mass of a pilot-glider system shortly after take-off. This would pitch the nose of the glider upward at some 80 degree angle above normal flight (arctan 4). If the towline or weak link broke under those conditions, the glider would whip-stall at that low altitude and plumet into the ground. And if the towing were not CM or if the glider were in a lockout, the situation would probably be even worse.
Donnell correctly states that:
The appropriate strength of a weaklink does not depend upon weather conditions or the flight attitude of the glider (turbulence, wind gradient, lockouts, etc.). It is impossible to design a weaklink to release the pilot when he looses flight control because there is no correlation between towline tension and flight control. (A pilot may be in perfect control under high tension but out of control under low tension.)
but immediately goes on to say:
A weak link can only be designed to release the glider under the worst possible conditions before the towing forces exceed the limits of safe recovery when the weaklink breaks.
Am I the only one who sees those two snippets as mutually exclusive?
I am sorry you find those two statements mutually exclusive. The key word in the first paragraph is "flight" and the key word in the second is "recovery." A pilot may well be able to control the glider in flight with a 10 g towing force. But very few pilots could control the glider immediately after that 10 g towing force suddenly became a 0. It would take an expert aerobatic pilot both time and altitude to get the glider back under control. But most non-aerobatic pilots would find it almost impossible to recover from a whip-stall safely, especially if it occurred near the ground.
For many years I subjected myself to the tyranny of the conventional "wisdom" that the only acceptable weak link for a solo glider of any weight is a single loop of 130 pound Greenspot at the end of a bridle.
I hook up at about 320 pounds and with that junk at the top end of my two point bridle I get AT BEST 0.76 Gs. (At worst I get 0.39 Gs but let's ignore that for the moment.)
I'm glad you finally learned that one size does not fit all and that the number of g's is the correct unit of measure.
The last time I remember being locked out (three years ago - at altitude) I was on my ear - thirty degrees beyond the placarded roll limit of my glider - before my brain finished connecting to my hand. And the little string was still doing just fine.
Karen hooks up at 200 pounds and - of course - uses that same weak link (which she's never broken) so she's limited to a max of 1.22 Gs. I'm thinking she could win an aerobatics competition without ever hitting her release.
Practically speaking, I don't believe that - given enough air - there has ever been an incident of any pilot of any skill level having a problem recovering from any attitude achievable while connected to a tug through a weak link of any strength.
I am glad to hear this. Perhaps your experience has been with reasonably well tested towing operations that try to minimize the chances of any kind of danger. Furthermore, one of the characteristics of aerotowing is that it regulates towline tension by matching the speed of the tug with that of the glider. In the early days before the Dragonfly this was a problem because the stall speed of the typical tug was near or above the maximum speed of the glider. In those days, if the glider pilot did anything except stuff the control bar, the single-surface glider would shoot upward and sometimes drive the tug downward. I guess things have improved. But I still believe, "Anything that can go wrong will go wrong." It is only a matter of time.
For the purpose of this discussion we're only hurting and killing AT people who are too low to be able to recover and weak links have never been issues in these scenarios.
If a weak link is too weak, it could contribute to this problem by increasing the number of un-intended releases at low altitude.
I hope we can all agree that there's no way freakin' way that those situations can be safely and reliably defused by weak links. Those problems have to be mitigated by the development of flying judgment and skill, use of reliable and easily actuated releases at both ends of the tow line, liberal use of wind streamers, and correlation of conditions to skill level.
Yes, I agree.
So I don't agree that it is appropriate to scale weak link rating to pilot skill level. This seems to carry the false assumption that the weaker the link the safer the flight and - trust me - there are plenty of situations in which the last place you want to find yourself is off tow. I can think of at least two people who were killed because they really needed line tension and couldn't get it and one who is alive and well because he did.
In most forms of towing, a weak link that is too weak is more of a nuisence than a danger. As long as the break occurs while a clear landing area is below, the pilot simply flies down and lands. However, aerotowing has its own unique characteristics that may well alter the situation. Dolly take-offs, speed-regulated tension, critical flight position of the glider relative to the tug, and limited take-off and landing area, are all unique to aerotowing. Therefore, an aerotow weak link needs to be strong enough to stand up under normal take-off and flight operations.
Nevertheless, you yourself mentioned that a weak link strong enough for one pilot to fly comfortably could well put another pilot in aerobatic flight. So, again, one size does not fit all.
There is another characteristic that distinguishes aerotowing from other forms of towing. Any pilot that is awarded an AT rating or allowed to solo must have demonstrated the ability to control the glider under normal tow operations. This includes the skill to keep the glider properly positioned behind the tug in typical thermal conditions. Such a skill level is considerably greater than that of rank beginners learning to hang glide by towing. Clearly, beginners just learning to tow do not have the ability to recover from a 1.5 g weak link break. They should be flying with a towline tension around 0.5 g and have a weak link that breaks somewhere around .75 g - surely no greater than 1 g.
On the other hand, any rated tow pilot should have the skills and ability to recover from a 1.5 g weak link break (or even a 2 g break). So in the case of aerotowing, I tend to agree with your above statement. However, in general I still believe that the weak link break strength should be adjusted to pilot skill for hang-1 and hang-2 pilots.
The way things are almost universally practiced now is... The smaller you are - the higher G rating you get. Brilliant.
And it gets even worse 'cause the bigger you are the faster you degrade a marginal weak link. Therefore Karen may start out with a 1.22 G weak link and end up with the same at half a mile up. That same weak link - 0.76 Gs for me when I put it on the bridle - starts breaking fibers as soon as the tug starts moving and can fail before I get to a hundred feet.
This is one of the main reasons I use the Linknife as my primary release. I have never had it fail to cut the weak link and release me from flight when activated. Therefore, every flight utilizes a fresh, new weak link. And every pilot can use the weak link that he or she finds comfortable flying with.
The FAA - with respect to sailplane towing - specifies a 0.8 to 2.0 G weak link range. I presume they do this to define limits for safety. Three observations:
- They don't correlate anything inside this range to pilot skill level.
- It appears that they consider anything under 0.8 Gs to be dangerous. So do I.
- If these are indeed reasonable lower and upper safety limits and G rating has no correlation to pilot skill then the safest number - the one or which EVERYBODY should be shooting - is the one in the middle - 1.4 Gs.
Again, everyone piloting a sailplane solo and everyone rated to pilot a hang glider solo has similar skills. Certainly they have mastered the minimum safe skills to pilot the gliders under typical conditions. Therefore, a weak link that breaks anywhere in the 0.8 to 2 g range should be appropriate. Somewhere in the middle (about 1.4 g) may even be more appropriate. However, I see no good reason for everyone to shoot for the exactly that same value. Anyone skilled enough to recover from a 2 g break can recover from a 0.8 g break. They do not need to limit themselves to 1.4 g. However, when they get above 2 g's they are beginning to push the envelope of safety. And the farther they get below 0.8 g's they more they are asking for unexpected pre-mature releases over potentially dangerous terrain.
Also, I'm not buying that because the normal tension involved in forward is less than that involved in downward pulling towing that you scale the weak links accordingly. If anything - correct me if I'm wrong - it should be = the opposite.
Increasing the tension pulling forward increases the glider's air speed until the nose can no longer be kept down. (The effect of a 1-g forward tension is the same as if the glider were being flown in free-flight at a downward angle of 45 degrees. A 2-g forward tow tension is equivalent to a 60 degree dive. No hang glider can maintain such dive angles for very long. Their increasing air speed will soon force them to start pulling up out of the dive.) When the nose comes up the forward speed of the glider will decrease and the position of the glider will become dangerously high possibly forcing the tug down. Unless the tug also slows down, the difference in air speed will increase the tension even more as the situation worsens until either the weak link breaks or one of the pilots release. Then the issue becomes that of how to recover safely. A weak weak-link prevents this situation from becoming as extreme as a strong weak-link allows.
In aerotowing you're not much worried about excess forward pulling tension 'cause that "problem" is gonna take care of itself pretty fast by translating to speed and altitude. The situation in which it's gonna be desirable to lose tension real quick is when the glider has rolled so far away from the tug that it ain't coming back and that is not a forward pulling scenario.
Aerotowing should never be a "downward" pull. So the weak link break point should ALWAYS be designed for that of forward pull. You should NEVER use a stronger down-pull weak link (say 3 g's) while aerotowing for pricely the reason you mentioned above. As soon as the aerotowing situation becomes a down-pull, the weaker forward-pull link needs to break.
And since aerotowing is speed controlled the tension starts going up fast when you start getting out of kilter. And - trust me - you don't want to be popping off tow every time you have to plow through a little turbulence.
Conversely, since most downward pulling towing is tension controlled, you can generally get away with a lower rated weak link 'cause normally it's impossible to get much of a deviation no matter what you do..
It is only the forward component of any tow force that makes the glider climb. The downward component only adds to the effective weight on the glider. Therefore, if one is towing with a towline at an angle of 60 degrees down (i.e. the glider is toping out above the ground tow vehicle), a towline tension of 1 g will only produce 0.5 g of forward thrust - enought to maintain flight even with the added weight, but not enough to climb appreciable. Unlike aerotowing which has unlimited sky in which to climb, ground towing usually has a limited space. Therefore, the only way to increase the release altitude is to climb with a forward thrust approaching 1 g. This means the towline needs to have 2 g's of tension at a 60 degree towline angle and 3 g's at 70 degrees. Such tensions pulling forward could be desasterous if the weak link breaks. But such a break at 60 or 70 degrees simply lightens the load on the glider and presents only a minor control problem. Therefore, down-towig may need and can safely use a weak link of 3 g's or more, while forward towing becomed unacceptably dangerous beyone 2 g's.
And if the FAA has anything to say with respect to weak link safety ranges being different for aero and winch towing - I can't find it.
I doubt if the FAA makes such a distinction. If I am not mistaken, most sail planes are towed from the nose of the glider. Therefore, aerotowing is forward towing. On the other hand, ground towing from the nose would tend to pull the glider's nose down. So one would need to limit the downward towline tension to similar values as forward towing. (A 3-g downward pull on the glider's nose could present a major control problem.) Even if the towline is attached to the center of mass of the sailplane so it could handle higher tow tensions when topping out, the fact that it must take off with forward towing means the weak link should be designed for forward towing. If it were designed for down-towing, the weak link would be too strong for the early part of the flight.
In the case of hang gliders, platform towing is the only mode that consistently pulls downward throughout the whole flight when performed properly. All other forms of towing use forward pull at least during the early part of the flight. Therefore, they should all use a forward-pull weak link. Even platform towing can revert to forward pull if done improperly. I have seen cases where the glider would launch and the vehicle would race forward at high speed to lengthen the towline before the glider could gain significant altitude. This converted the down-pull into a forward-pull even while using a down-pull weak link. The glider climbed out at a 45 to 60 degree angle at low altitude. If the payout winch had jammed for some reason, the down-pull weak link would have broken, the glider would have whip-stalled, and the pilot would have been killed. I was appauled at such an operation. But it was SOP for that group. They had done it many, many times without a mishap.
Ridgely has pulled something on the order of forty thousand tows over the course of its ten seasons. Let's be REAL generous and say that they're only breaking weak links at the rate of one per twenty flights. That's two thousand pops. The percentage of those that were desired and necessary for the safety of the flight is ZERO. So what do we learn from these numbers?
We learn that the weak links are consistently breaking before the situation becomes dangerous, exactly as they are designed and intended to do. If you really want to increase the number of weak link breaks that are deemed "desired and necessary for the safety of the flights", simply increase the weak link break point to 4 g's, or better yet, eliminate the weak link altogether.
the ONLY PROVEN ACCEPTABLY SAFE weaklink is a string deliberately inserted into the towline which consistently breaks at a known and specified tension.
OK. You've got me here. Perhaps the Tost system has proven itself to you and to others to be infallable. I cannot argue the point about its reliablity because I have never flown with that design. However, you yourself commented above that "the bigger you are the faster you degrade a marginal weak link". Therefore, I get the distinct impression that your weak link degrades in time (perhaps even during a single flight). Whether or not it can possibly jam and become stronger than intended, I cannot say. Perhaps you can.
However, I do know that strings never get stronger than intended and that using a new string every flight keeps them from getting weaker. Therefore, I still find a simple string to be the least expensive, most readily available, and most easily tailored device that meets the Skyting Criteria #7: INFALLABLE WEAK LINK.
I'd like to get some comments on these points 'cause the AT system is totally broken on this issue. I think the first step to fixing it is to get the USHPA to amend its rules by specifying a minimum allowable weak link rating which is in accordance with that required by the FAA.
I hope my comments are what you were looking for. I also hope these comments help you see that one size does not fit all. Different forms of towing demand different strength weak links to optimize the safety. If USHPA modifies the rules to optimize towing safety, it will be limiting the safety of other forms. If it tries to establish different optimum rules for every concievable form of towing, the rules will become so cumbersome that people will ignore them. Certainly, general guidelines would be commendable, but I question whether a universal minimum allowable weak link rating in accordanc with general aviation sailplane towing would increase or decrease towing safety.
*
Tad Eareckson - 2008/10/15 14:19:13 UTC
6692
This is gonna be REAL long. Sorry...
First off, some background...
My first relatively high flight took place on the Outer Banks, a month shy of 28 years ago yesterday, hooked up to a Yarnell winch via a three point bridle. I don't recall a weak link being a component of the system. Two days shy of five months afterwards my then Kitty Hawk Kites fellow instructor roommate would lock out and die on a similar configuration.
When your introductory article appeared in Hang Gliding magazine shortly thereafter I was fascinated and held my breath in anticipation of the first of three promised successive articles to expand on the Skyting principles.
The next month there was no article, no explanation - nothing.
I asked USHGA Board Member Les King what the hell happened and he related that the BOD had decided you were probably some sort of wacko and had thus arbitrarily cut you off. Several years after that when the towing culture had gotten it I talked to Les again and he said, "He was right - We were wrong."
So I can't begin to thank you enough for what you have done for hang gliding and my safe participation in that vital aspect of the sport.
And - with respect to the issue at hand - I also greatly appreciate the time and effort you took to respond to my post.
On to the points...
As luck would have it, it appears that Dynamic Flight revised their website VERY recently 'cause I had checked that link VERY recently. Try again though at:
Generally, with respect to your response, I may not have done a great job of making some of my positions clear so lemme give it another shot.
Most of my towing experience has been behind Dragonflies and that context is my primary focus.
I don't know what the minimum rating with which we can get away is but I'm wary of anything under 1.0 Gs. I saw Karen again yesterday and - at 1.2 Gs - she's never had a break and never been in a position in which she desired one.
For the past couple of seasons I've been flying at 1.4 Gs and am pretty happy knowing what that rating allows me to plow through. And - ignoring Peter for the moment for the sake of argument - I've got the best AT release system in the world. I'm pretty confident that I:
- will NEVER break a 1.4 G weak link; and
- can safely deal with whatever hits me down low
and am totally confident that I can blow tow faster than any weak link can be counted on to.
I didn't mean to imply that I would suggest that using a three or up G weak link would be acceptable. In my range of experience and observation, by the time you start getting to 1.4 the tow is over - forget about it - start again. So I would never recommend anything over that or 1.5.
Ideally I'd start with maybe 1.0 and start dialing up or, conceivably, down to find the edge at which unwanted breaks stop happening. Anybody feel like doing a science project? I don't 'cause I NEVER want to have another day ruined by an unwanted break, but, again, Karen seems to be doing fine at 1.22.
I don't have much of a problem with:
the sole purpose of a weak link is "to allow the aircraft to recover safely when the weak link does break".
but the unwashed masses interpret this to mean:
1. "to guarantee that the aircraft can recover safely when the weak link does break"; and/or
2. "to keep the aircraft from hitting the ground if I'm locked out low".
And, as we both agree, no weak link capable of accelerating the glider and dolly from a dead stop is gonna be able to fulfill those functions.
Also - though I take your point - I prefer to have people thinking about the release being the mechanism which allows the aircraft to recover safely when the situation has gone way south. Towing with the attitude that the weak link is gonna keep you out of trouble is more than a little bit like pushing your flying safety margins 'cause - what the hell - there's always the parachute.
I did know from my earliest associations with weak links that one size does not fit all. But here's what happened...
The skygods who opened up the flight parks tied a Fisherman's Knot to form a loop of 130 pound Greenspot and put it on the end of a bridle with a Double Lark's Head such that the Fisherman's Knot was "isolated" from the tension and thus had no bearing on the breaking strength.
So two strands, two times 130 gets you 260, it's on one end of the bridle so double it. About 500 pounds of tow line tension. For me - 320 pounds - 1.56 Gs. Not bad. For Karen - 2.5 Gs. Hell, close enough. But fer chrisake we can't go any higher than that. Even if the weak links start going off like popcorn for no reason - which they did - and do - it would be dangerous to dial them up anymore, right?
Some years ago I questioned that assumption, hauled out the bathroom scales, and independently discovered - as I'm sure others had before me - that these things were only good for about half what the popular hypothesis predicted.
I pointed this discrepancy out to my local crew but by that time the culture had brainwashed itself into the enshrinement of the 140 (at best) pound weak link as the sacred and inviolable standard for all solo gliders regardless of their weights and what was happening at the runways. This is the religion I'm currently trying to eradicate.
Don't believe me about this? Check out what it STILL says at:
and play "How many things can you find wrong with this picture?".
Dragonflies...
I get the impression you haven't spent much time around a major Dragonfly flight park or Dragonfly launched competition.
The first time I aerotowed I foot launched my Comet 165 behind a Cosmos trike using a one point bridle and three ring release. Fast tug, relatively slow, pitch stable glider, couldn't get into my cocoon boot, tow force transmitted to me through my armpits. Had flashes of pain for days afterwards.
Unless you kept the bar stuffed at all times the glider would start getting above the tug and when it did you couldn't get it back down and the situation would deteriorate fast. I was looking straight down at the trike when I released.
I didn't get a second flight 'cause, with a glider in tow at a hundred feet, the gas tank worked free of the bungee cords restraining it and went through the prop. Wood fragments tore through the sail and the contents of the tank were transformed into a cloud of two stroke mix straight above me.
It ain't like that no more.
Dragonfly towing off of launch dollies is brain dead easy. The speed is great, the control and power is phenomenal, the safety is monotonous. Even with the crap that passes for release systems on most of the gliders, dangerous low level incidents are freakishly rare.
These damned weak links at best are way more than a nuisance - they're very often day killers. I actually think they're trashing something more like ten percent of our tows. For most gliders they should be holding from at least 250 to 400 pounds. They are REGULARLY failing at 125.
I can't say I've seen a lot of this myself but check this out from:
Kevin Carter - 2005/09/24 17:50:17 UTC
One pilot in the Texas Open had three premature releases in a row with glider damage on all three and different degrees of pilot injury. I
myself have had a low level release that caused minor injury.
Some of these gliders are having to land in propwash and other junk they'd rather not.
...you yourself mentioned that a weak link strong enough for one pilot to fly comfortably could well put another pilot in aerobatic flight.
The point that I was trying to make there was that even a weak link off the bottom end of a safety rating can (and did) put a pilot (me) into aerobatic flight. So if you're gonna tow in air worth towing in you'd better be able to recover from at least a ninety degree roll if you hafta wait for your string to pop.
Clearly, beginners just learning to tow do not have the ability to recover from a 1.5 g weak link break.
Beginners just learning to tow are going up tandem in today's world. When they solo they're restricted to really boring conditions - often early in the morning and late in the evening. They've got a release and the tug pilot has his eye on a mirror and his finger on a trigger. Beginner solo pilots just don't get in these situations anymore. And, besides, you don't worry about the student recovering from an aerobatic pop - you worry about him locking out low and slamming into the ground. And a 0.75 G weak link can't prevent that from happening - even with an experienced tow pilot. It happens. That's what the releases are for.
I've never heard of a student benefiting from a weak link break and Highland Aerosports has no recall of one after ten seasons of teaching.
In fact, I am only aware of one weak link break in the entire history of Dragonfly towing that was desired and necessary for the safety of the flight. And that incident involved some level of pilot error and a less than optimum release configuration.
Ignoring beginners for the moment... No, I don't see it as necessary to shoot for exactly 1.4 Gs either. I think there's a lot of latitude between "Shit!" and "HOLY SHIT!!!" But the one size fits all situation we have now is almost ALL THE FORMER. NOBODY (with the aforementioned exception) is saying "THANK GOD!!!" when they go.
But I can do weak links in rather fine (approximately 35 pound) increments and, since aerotowed hang gliders tend to keep their weak links with them, why not go for exactly 1.4?
Back to beginners...
-
The student - or any other pilot - MUST have the capability of reacting faster than the weak link to safely climb through that first hundred foot danger zone.
That is the WEAK LINK of the flight.
If he can't manage that why worry whether or not he can recover from a
1.4 G weak link break at altitude?
This is the point Steve Kroop was trying to make with:
Weak links are there to protect the equipment not the glider pilot.
All you're trying to do with the weak link is make sure that the pilot is left with something to fly back down if everything else is fubar.
You give the student a parachute but if you think there's a reasonable chance that he's gonna need it you don't send him up.
You give the student a weak link but if you think there's a reasonable chance that he's gonna need it you don't send him up.
Both of those also apply for a Hang V aerobatics champion.
-
With respect to the direction of tow tension (forward/down)...
I didn't mean to imply that I thought that SUSTAINED high tension from the tug in front of you was OK. I should have specified that I was discussing a short duration surge situation. Dragonflies don't tow us with sustained high pull and the only situation I can envision in which you might want the weak link to fail with the tug straight in front of you would be one in which a lot of slack between the two planes would be taken up FAST. And I don't recall an instance of that happening with a 250' Spectra tow line.
It's been a long time since I've been around ground based towing. Based upon your explanation of all the force vector stuff I'm now thinking I was, at least to some extent, wrong with respect to my comparisons.
But - if I can use the royal "we"...
We Dragonfly towees don't have significant problems getting too high or low. The primary situation in which we want/need to / might as well as end the relationship is when we're going this way and the tug is going that. We can get clobbered and rolled hard and disappear from the mirror real fast. The tension builds up real fast too and when that happens our bellies - not our noses - are pointing in the general direction of the tug. Gravity is still somewhere down there past one of our wingtips but we're feeling a lot of artificial gravity component kinda like a winch towed glider does.
Flavors...
No, when I was talking about weak link degradation I was referring to the Greenspot loops. I've done EXTENSIVE bench testing on my various "shear link" configurations and they've got excellent tolerances / predictability and they don't degrade. You can take them right up to the brink of their rating and back off and they're still good for their rating.
I'm predicting that you can get a 1.4 G bridle link, fly it every good day for the next ten years without it failing, and still have it good to within several percentage points of 1.4. And it's impossible for it to jam and/or get stronger. You wanna limit the tow to 1.4, the tow is limited to 1.4.
I don't know how long the Tost system has been around but I suspect it's been a while and it's apparently kept the DHV, FAA, and sailplane pilots happy. I've got a couple of sets but have never used them. Marco Vento uses them for his operation in Portugal however and reports excellent results.
My shear links are a hybrid of the traditional hang gliding and Tost weak links.
Like hang gliding links they're based on strands of string. In my case the string is nylon dental floss and the strength is determined by the number of stitches joining two elements. (The Greenspot is secured with knotting.)
Like the Tost links the critical element (floss versus drilled metal inserts) is isolated from the friction and wear of interaction with release mechanisms.
We learn that the weak links are consistently breaking before the situation becomes dangerous, exactly as they are designed and intended to do.
These damned weak links are commonly breaking with the glider straight and level behind the tug in totally dead air. They are often breaking before the glider even starts moving. THEY'RE NOT DOING THEIR FREAKIN' JOB. They're blowing at 0.4 Gs. They're not breaking before the situation becomes dangerous - They're breaking before the situation has any chance of becoming enjoyable.
They are not making things safer. They are - without any doubt - only making things more dangerous.
Again - nobody designed these things. It's nothing but the blind leading the blind. If you want to make aerotowing REAL safe then just use a Red Rose tea bag string for your weak link and then the only things you'll have to worry about will be taxes, mosquitoes, and dust devils.
Lemme tell you about a couple of conversations I've had this past season.
We've got a really excellent high time / old time pilot who recently started flying a rigid wing. Somebody brought it to my attention that he had recently had a string of ten consecutive weak link failures. I talked with him for about an hour explaining to him what a weak link was and trying to convince him that the reason this was happening was not because his pitch control movements were too abrupt but rather because his weak link was half as strong as it needed to be.
His eye's lit with revelation when I pointed out that his three hundred pound slightly dumbed down sailplane was using the same weak link as Karen. One of them was wrong. I convinced him to double his Greenspot to get his tow line up from 0.5 to 1.3 Gs.
By the next time I saw him one of the crew had gotten to him and sent him back to Stupid Ville. So now, again, he's allowing his control decisions to be dictated by the Sacred Fuzz.
Monday I was talking to a Hang II whose soul I am trying to save. He had just had a couple of morning flights in a strong choppy wind coming straight down the runway and broke a link as he was in the process of bringing it back after being kicked down and to the side a little.
"I guess I must have pushed out too abruptly."
"No, Raj! You popped off 'cause you're using a weak link half the strength you need! Like I told you last weekend."
But his eyes dropped down and to the side and I can't get anywhere 'cause:
1. I'm telling him one thing and his instructors are telling him another; and
2. there's nothing in the SOPs to which I can point to prove to him that he's operating out of specs.
We shouldn't be popping links when we've got things under control and are coming back. We should be breaking them after we're out of other options.
If USHPA modifies the rules to optimize towing safety, it will be limiting the safety of other forms. If it tries to establish different optimum rules for every concievable form of towing, the rules will become so cumbersome that people will ignore them.
So since when have people been paying any attention whatsoever to the rules?
With each flight, demonstrates a method of establishing that the pilot is hooked in just prior to launch.
A release must be placed at the hang glider end of the tow line within easy reach of the pilot.
So take a look at our gold standard "tried and true" two point release in a somewhat demanding scenario:
Where's the hand? Where's the actuator (brake lever)? What happens when you lock out to port and fall to the low side? Within easy reach until you really need it.
This release shall be operational with zero tow line force up to twice the rated breaking strength of the weak link.
See how the ubiquitous Bailey release holds up under that loading.
Here's the SOP under which we actually operate:
You use what you want and I'll use what I want, that's the beauty of this sport, we are all responsible for our own choice in equipment.
A weak link must be placed at both ends of the tow line. The weak link at the glider end must have a breaking strength that will break before the towline tension exceeds twice the weight of the hang glider pilot and glider combination. The weak link at the tow plane end of the towline should break with a towline tension approximately 100lbs. greater than the glider end.
We've already got a specification for the maximum allowable rating for the glider. We've already got a specification for the minimum allowable rating for the tug.
WE NEED A MINIMUM ALLOWABLE RATING FOR THE GLIDER. This is not a cumbersome expansion of the bureaucracy.
So, again, one size does not fit all.
BUT THIS STUPID CULTURE IS OPERATING ON A ONE SIZE FITS ALL STANDARD WHICH IS EFFECTIVELY PREVENTING MANY PEOPLE FROM TOWING AT OVER A HALF A G.
And there have been competitors who have gotten so sick of this crap that they've used fake unbreakable weak link decoys to get through security and get a chance to make it into the air.
...an aerotow weak link needs to be strong enough to stand up under normal take-off and flight operations.
They (beginners) should be flying with a towline tension around 0.5 g and have a weak link that breaks somewhere around .75 g - surely no greater than 1 g.
OK. So we are apparently in agreement that we need a minimum rating?
1.0 Gs I can easily live with. Below that I start getting unhappy.
Lines and metal structures have Breaking Strength and Safe Working Load ratings and they don't tend to be very close together. My problem with sinking below 1.0...
Dragonflies ARE towing people at about 0.5 Gs. But when you go through turbulence the needle does a lot of swinging. And even if you don't hit the Breaking Strength of the polyester string you're going WAY beyond its SWL rating. And when you do that a 140 pound weak link doesn't remain a 140 pound weak link for very long. It rapidly becomes a 70 pound weak link. And that's the situation we have now.
If we can agree on 1.0 I will be a very happy camper.
Well, if you've made it this far down, I thank you again for your time and attention. And I will be extremely interested in any responses you may have.
*
Tad Eareckson - 2008/10/1711:45:06 UTC
6703
Yeah, I've probably already used up my bandwidth allocation for the next three years but...
Skyting Criteria
GROUP 2 - Safe Transition
06: Reliable Releases
The release devices and their activation methods must be sturdy, rapid, and reliable. (Release activation MUST be readily accessible to the pilot regardless of where his hands are or where his body has shifted. Only single-point release systems should be used.)
I believe virtually all aerotowing nowadays is dolly launched. If not, it should be. Foot launching was about half of what got Robin Strid killed.
When you dolly launch you start out with your hands on the basetube - right where God intended them to be to best control the glider - and leave them there the rest of the afternoon until you decide you'd rather land on your feet than roll in.
Since the very beginning of Dragonfly towing we have had the option of reliable two point releases with basetube mounted actuators - yet we generally elect to velcro them to a downtube.
The release configuration illustrated in those dolly wreck photos violates Criterion 06 on a couple of levels.
The better your release system the less you think of your weak link as something you're gonna rely on to keep you safe.
Just like the parachutes we never use, the weak link can only be of any possible use when the situation has been allowed to degrade to the point of fubar - by people at BOTH ends of the line. This NEVER happens faster than a fully awake Dragonfly towee using good equipment can react - despite the nightmare scenarios we all envision.
As gleaned from the USHGA Aerotowing and Tug Pilot Guidelines, these are the circumstances in which an immediate release is called for...
-
Glider noses over the dolly.
Glider is low and has diverged more than twenty degrees from the tow.
Oscillation worsens at low altitude. Release as the glider is starting to recover from a cycle.
Glider rolls past 45 degrees.
At takeoff the glider climbs so far above position that it threatens to nose in the tug.
When low the glider fails respond to a roll correction within a second.
-
In none of those scenarios can you afford to be admiring the scenery while you wait for your weak link to kick in.
07: Infallible Weak Link
The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation. (There is always the possibility something unexpected can happen. Breaking point should be appropriate for the weight and experience of the pilot, not to exceed 1G - sum of all towed parts.)
Different forms of towing demand different strength weak links to optimize the safety.
Therefore, down-towing may need and can safely use a weak link of 3 g's or more, while forward towing becomes unacceptably dangerous beyond 2 g's.
But here in 07 you've got us ALL capped at 1.0 - which I'm arguing should be the absolute MINIMUM for aerotowing.
I realize that the Dragonfly was way off in the future and don't believe that platform towing was around when you wrote this but maybe it's time for a revision.
The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation.
The only way a weak link can keep a glider within the limits of safe operation is to break before the glider starts moving (and I've seen plenty of them that do just that).
If the weak link is strong enough to get the glider moving it's strong enough to get it in the air and hold long enough to put it into a nonrecoverable fatal low level lockout. At altitude it's strong enough to hold well beyond the point of the glider's placarded roll limit.
If you try to make it weak enough to keep you within this "limit for safe operation" you're also gonna make it weak enough to fail in a situation in which tow tension is the only thing keeping you alive.
There is no such thing as "the limit for safe operation". It's make-believe, like floating crossbars, elves, gremlins, and Eskimos. All there is a wide noncritical gray area of tradeoffs which I'm contending is optimized at 1.4 regardless of who's on the back end of the rope.
Notice a couple of things we're NOT seeing here?
This is the third forum upon which I've raised this issue. No one from my local crowd, TUGS, or here has yet posted this message:
-
Hey Tad,
You're full o' shit.
Lemme tell you 'bout the time two years ago at Quest.
There I was - thought I was gonna die. Seventy-five feet off the runway...
...
...and if that weak link hadn't failed just in time I wouldn't be here talking about it.
-
We've got the experience on these wires of direct participation in and knowledge of - I'm guessing - hundreds of thousands of tows from several big flight parks and lotsa competitions from people at both ends of the string and so far I've got NADA.
Also...
As I've said before - We ARE towing in a one size fits all world. NOBODY dumbs down the Sacred Greenspot for first time solo 200 pound gliders. They get exactly the same weak link I - almost Hang V, tow experience going back to 1980, 320 pounds - do.
They get a lifetime 1.2 G weak link - I, because of the SWL phenomenon, get something around half of that.
So shouldn't we be seeing a trend in which the tiny little girls - especially of the Hang II variety - are being drained from the gene pool?
What I'm seeing is that they're the only ones NOT having problems. It's everyone else - without regard to race, creed, gender, sexual orientation, or Hang Rating - who is coming down hard and breaking downtubes.
One point O or bust.
*
Tad Eareckson - 2008/10/18 11:45:26 UTC
6704
As long as I'm stuck in babble mode...
With respect to Tracy's Post #4592, 2005/02/08 19:16:10 UTC...
The sailplane guys have been doing this for a long time, and there are many hang glider pilots and quite a few tug pilots who don't understand what the sailplane guys have learned over the years. It certainly would help if hang glider towing methods and training were standardized to the degree that they are in the sailplane world.
Rat own!
0.8 (or 1.0) to 2.0 Gs.
Anybody know what the weak link / tow line break rate is for sailplanes? Let's duplicate it.
Both sailplanes and aerotowed hang gliders use properly-rated weaklinks at both ends for a very good reason.
I, of course, am taking issue with the premise that hang gliders are using properly rated weaklinks.
Primarily, the use of a weak link is to save the tug pilot's behind, by preventing structural and/or control failure...
The flimsiest of weak links can be counted on to allow the glider to pull the tug up by the tail and put it into the ground.
...the hang glider pilot should only use one weaklink, at the upper attach point in a 3 point bridle system, to prevent tucking should the bridle release at the low end and snag the ring.
So should the bridle release at the high end and snag the ring there's no longer a weak link at the back end of the tow. Violates Skyting Criterion 07, USHPA SOP 12-02.10:B:5, and FAA FAR Part 91.309.
I've got a 1.4 G / 288 pound weak link at the top of my bridle and a 336 pounder at the bottom. If I get a wrap the bottom one is shock loaded and I'm off.
*
Tad Eareckson - 2008/10/23 12:59:30 UTC
6711
It sure would be nice if we could get some back and forth on this and get a consensus on what's right and what ain't. But apparently not. So I figured that it wasn't worth the risk of being treated like a potted plant after making the trip to Chattanooga. But I'll continue the monologue a bit here on the off chance that some of this might sink in enough to eventually get us to clean up our act.
-
Stuart,
Belated thanks for your comments on banner towing which support the main point of the understanding which is - again...
The weak link is not there to keep you in control of the situation. It's there to leave you with enough aircraft to be capable of regaining control of the situation.
P.S.
Thanks also for the information up on your website regarding the configuration of your weak link testing rig. A couple of years ago it saved me from some Rube Goldbergish paths I had in mind when I was thinking about how to build mine.
Mine, by the way, uses a Harken 16 mm AirBlock triple block and tackle system to take the slack out of and preload things and a threaded rod to fine tune and/or really crank up the tension. An H-091-DUZ Bimba Hydraulic Cylinder gets me up to 388 pounds and twice that when I reconfigure for a 2:1 mechanical advantage.
Donnell Hewett - 2008/10/14 00:49:34 UTC
We learn that the weak links are consistently breaking before the situation becomes dangerous, exactly as they are designed and intended to do.
Anybody who thinks that a weak link should or can be designed to break before a situation becomes dangerous either hasn't been around aerotowing very much or is blind to what's actually happening in the air.
People have been killed as a result of low level lockouts using sub 1.0 G weak links. They absolutely do not consistently break before situations become dangerous.
The components of the tow system which are, in fact, designed to prevent the situation from becoming dangerous are the pilots, releases, launch dolly, and wind streamers. Although some pilots and releases are designed better than others, I know of ZERO incidents that couldn't have been defused better by a good combination of those than by waiting around for the weak link to break.
I know of only one accident in the entire history of aerotowing that occurred after the tow had gotten above immediate striking range of the ground. 2006/01/19, Tocumwal, Australia. Weak links at both ends of the tow line broke at 500' and the pilot died anyway. That situation became toast because of too LITTLE tension - the slack tow line tied itself around a side wire.
I know of only one incident - 2008/07/20, Zapata - in the entire history of aerotowing in which a weak link break was desired and at least partially necessary. And in that case - at altitude - the pilot was smacked by the biggest freakin' hammer he had ever encountered in an extensive flying career, using a release which required a reach, and partially asleep at the switch (having problems cleating a VG cord).
So, historically...
Weak links are not saving people down low where it really matters and the low level breaks we do get just make the situation dangerous. Instead of being in control of the flight, the pilot using an understrength weak link is rolling dice to predict what's gonna happen next.
Up high a pilot who was focused on the task at hand and had a finger on the trigger has never benefited from a weak link break.
And a weak link break at any altitude - dangerous low, in and of itself no more than a major headache high - subjects the pilot again to the two most dangerous aspects of flight - takeoff and landing. Twice as many takeoffs and landings per hour airtime - twice as many injuries and fatalities.
Based on the crap I see while I'm baking in the launch line I'm comfortable saying we're breaking links on every bit of five, quite possibly ten percent of our solo tows.
If it's true that these tows are out of control to the level that these breaks are doing us some good I think we all need to question the way we're doing business or find a new hobby.
This, of course, is nonsense. If it had any validity then people who were flying 1 G plus weak links because of the accident of their size - like Karen - or their conscious equipment choice - like me and my tiny cult of thinkers - and never breaking them would all be carried off the field on stretchers once or twice a season.
That ain't happening and the reason it ain't happening is not 'cause we're all vastly superior tow pilots.
If you really want to increase the number of weak link breaks that are deemed "desired and necessary for the safety of the flights", simply increase the weak link break point to 4 g's, or better yet, eliminate the weak link altogether.
Nobody's talking about increasing the weak link to 4 Gs. I'm not even talking about going up to the USHPA limit.
I'm talking about:
1. Understanding the purpose of a weak link and what it can/does and can't/doesn't do;
2. Using a 1.4 G weak link that holds when you want it to and fails long before you need it to (which for just about everyone, myself included, is NEVER); and
3. Growing up and understanding that a weak link has a limit below which it becomes dangerous no matter who's on the back end of the line, taking a clue from the FAA, and defining that limit as 0.8 Gs or better.
*
Want to buy (WTB) Weak link tester
Peter Birren - 2008/10/26 22:20:33 UTC
6718
Given that it's entirely possible for a glider, whether on static, payout or aerotow, to lock out and pound in with minimum tow tension, and given that it's neigh unto impossible for a pilot to whip the glider in such a fashion as to purposely break the weaklink, I see he weaklink as most necessary to prevent the glider/pilot from being dragged after an initial launch accident.
Once well away from the ground, the pilot (1) must do everything possible to maintain control and to stay in-line with the tow force and (2) release when too far off the force line.
Relying on a weaklink to prevent a lockout or anything other than holding on for the whole tow is placing trust in the wrong place.
Too weak of a link will very likely cause a premature end to the tow; too strong and it might not break should the pilot mess up at launch.
*
Tad Eareckson - 2008/10/27 22:47:21 UTC
6725
Moving the discussion back over here and responding to Post 6718...
If you really wanna prevent yourself from being dragged you start out on a dolly compliant with the specifications in the Aerotowing Guidelines (earlier cited by Tracy) and you have your finger on the release trigger.
Nice illustration of just one of the many unpleasant consequences which can and do result from this philosophy of asking the weak link
to do the job of the release.
I've just decided to define a parameter of an AT release:
If you have to move your hand to reach for the actuator - it ain't an AT release.
I think the world will spin a lot better if we drink Dr. Freeman's Kool-Aid, recognize that the weak link has but one function, and stop trying to ask and tweak it to multitask.
The purpose of a weak link is solely to prevent the tow force from increasing to a point that the glider can be stressed close to or beyond its structural limits.
In the Finger Lakes wreck the weak link was asked to function as a release. It said, "OK, I'll give it a shot, but you might not be real
happy with the results."
The release is there to protect you, the weak link is only there to protect the equipment and can only properly function if you've got enough altitude to play with.
Lemme address a point from Dr. Hewett's 2008/10/14 00:49:34 UTC post...
Imagine a 4 g towline pulling forward on a the center-of-mass of a pilot-glider system shortly after take-off. This would pitch the nose of the glider upward at some 80 degree angle above normal flight (arctan 4). If the towline or weak link broke under those conditions, the glider would whip-stall at that low altitude and plumet into the ground.
First, I'm having a real hard time imagining a Dragonfly with a 914 Rotax (or any other hang glider tow system) being able to deliver something on the order of a twelve hundred pound forward pull. With the turbocharger kicked in I only read about 155 pounds which, for me, is less than half a G.
Next, say at a hundred feet... Anyone who wants to whip stall, can - regardless of whether he's on or off tow or, in the former case, using a 4.0 or 0.5 G weak link.
So I don't really see the point. This scenario assumes that the glider pilot is brain dead. You don't tow a brain dead pilot.
And since a pilot with prospects considerably better than organ donation can get killed in a low level lockout using a 0.5 G weak link whilst making a good faith effort not to... Why worry about one scenario and not the other?
I think we need to define and review some elements of the tow system and understand what they can and can't do.
-
FORCES (potentially lethal)
- Nature: Must be worked around.
- Tension: Allows Glider to climb from flat ground.
PERSONNEL
- Pilot: Controls Controllable Equipment.
CONTROLLABLE EQUIPMENT
- Glider: Keeps Pilot alive in air.
- Release: Eliminates Tension from the Forces equation.
FUSE
- Weak Link: Prevents Tension from breaking Glider.
-
Now if everybody just does his own job, doesn't expect others to do it for him, and stays on his own turf...
You are convinced that a 1.4 G weaklink is good. From my experience, that's way too high... anything over 1 G creates a "strong link" that somewhat defeats the purpose.
and
Too weak of a link will very likely cause a premature end to the tow; too strong and it might not break should the pilot mess up at launch.
The dollies at Ridgely are all stable and - despite the fact that I'm usually the only person around who bothers to do anything about pressure and people frequently end up with something with as many as three totally flat tires - in the course of forty thousand tows there's never been a consequential problem on launch that wasn't caused by an understrength weak link.
And the real cost of an understrength weak link isn't just the couple of pennies for the string. It generally starts off in double digits - dollars, not pennies - and can easily go triple when you start folding downtubes.
I'm guessing the Finger Lakes weak link wasn't much better than 0.85 Gs. And still the pilot got a lip full of stitches and the glider sustained hundreds of dollars of damage to frame and sail. And since the weak link didn't fail until after the nose plant I suspect the results would have been no worse in the least with a weak link of twice the strength.
Your opinion is that 1.4 Gs is "way too high". I'm still waiting to hear of ANY incident or evidence which supports that assertion.
You trying to tell me the pilot had time to release? Not a prayer.
I know about this type of accident because it happened to me, breaking 4 ribs and my larynx... and I was aerotowing using a dolly. The shit happened so fast there was no room for thought much less action. But I wasn't dragged because the weaklink did its job and broke immediately on impact.
If you have to move your hand to reach for the actuator - it ain't an AT release.
You're focusing on AT but there's a lot more towing going on then at the flat/smooth-ground country club sites. On a crowned country road, off the back of a truck or trailer... ain't a place for a dolly or a threaded bridle of any type.
If your belief is that the weaklink is there mainly to protect the equipment and break before the glider breaks, I suggest you try to break one while being towed. With a 1.4G link, which in my case is about 385 pounds, I may as well not even bother because a slightly worn towline will break at about that tension.
No, you will not be happy with the result of a weaklink breaking should the pilot stumble and the glider impact the ground, but it's still better than being dragged until the tug stops (or in the case of static towing, the vehicle stops and the tension on the towline eases).
Imagine if you will, just coming off the cart and center punching a thermal which takes you instantly straight up while the tug is still on the ground. Know what happens? VERY high towline forces and an over-the-top lockout. You'll have both hands on the basetube pulling it well past your knees but the glider doesn't come down and still the weaklink doesn't break (.8G). So you pull whatever release you have but the one hand still on the basetube isn't enough to hold the nose down and you pop up and over into an unplanned semi-loop. Been there, done that... at maybe 200 feet agl.
Now maybe if I'd pushed out quickly, real quick-like, the weaklink might have broken. That, however, would have possibly also put the tug pilot and plane in jeopardy if it didn't break.
Scenario: at a static tow site, driver takes his eyes off the gauge to watch the pilot in the rear view mirror. When he looks back, the gauge is reading zero, so he steps on the gas... but the needle had gone all the way around to about 350 lbs and here he was giving more tension. Pilot stuff the bar 'cuz to let go as low as he was would be riskier. Pilot rode it out until the .8G weaklink broke, holding the bar to his knees and riding it "over the top" to safe, level flight. (shoulda seen the pilot's eyes... big as the proverbial saucers.)
First, I'm having a real hard time imagining a Dragonfly with a 914 Rotax (or any other hang glider tow system) being able to deliver something on the order of a twelve hundred pound forward pull. With the turbocharger kicked in I only read about 155 pounds which, for me, is less than half a G.
So if the 914 can only pull .5G, then why in Heaven's name do you need a 1.4G weaklink?
Nice that you've got a good place to aerotow with good dollies and all, but your "strong link" will have brought more hurt onto the pilot who crashed because it won't break soon enough. As for my incidents and evidence, the above stories should be enough but, if not, I can provide several others where the main thing proved (to me and others on-site) is that a less-than-1G weaklink is MUCH better than a strong link.
*
Tad Eareckson - 2008/10/28 17:17:16 UTC
6730
Peter,
Thanks very much for the detailed response and all the information.
I know you've got tons of experience with foot launched and ground based towing and I'm certainly not going to tell anyone how to operate in those environments. I will happily concede the points you make relevant to them.
I like to see as much safety built in to an operation as possible but if my local turf precluded the use of dollies I'd foot launch. But I'd expect the casualty rate related to getting off the ground to go from what it is now - zero - to something relatively unpleasant.
I'd be very interested to know what happened to precipitate the dolly wreck you experienced. In the one I referenced there had been prior warning that that configuration was not stable. And, again, at Ridgely there has never been a problem.
I don't know if there was time to think or react in the Finger Lakes wreck. But there was time for the photographer to get off at least two or three shots while the situation was somewhat salvageable. I know that doesn't necessarily tell us anything but there doesn't seem to be any overlap of the background while the show's in progress.
One thing's certain - the location of the brake lever way up and to the right didn't do anything to fatten the bag of options.
At Finger Lakes it's my opinion that it wouldn't have made any difference whether the weak link was the 0.85 G rating I'm guessing it was, the 0.5 it would've taken to get the glider rolling, or the 2.0 limit specified by the SOPs. Dragging wasn't an issue. What did the damage was the nose plant and associated sudden stop. And any weak link within that range would have failed immediately at that point.
From what I read about your own accident I'm guessing that weak length strength wasn't any more relevant. But I stand to be corrected.
I doubt we're ever gonna agree on the threaded versus closed bridle issue but - again - I see the advantage that comes with releasing the bridle up top as vastly outweighing the freedom from worrying about a wrap that you get with releasing between the tow line and the bridle.
I have had two wraps in my history of aerotowing and both of them were entirely attributable to deficiencies in bridle design which I subsequently corrected. Both of the wraps were non issues.
When I'm towing two point I'm protected by a 1.4 G weak link at the top end of the bridle and can release without moving my hand from the basetube or compromising my control of the glider.
If the bridle wraps I'm towing one point protected by a 1.0 G weak link at the back end of the wrapped bridle. And in both instances the shock loading resulting from the glider's deceleration was enough to blow that weak link under just normal, smooth, straight and level circumstances.
Even if it doesn't break I can leggo of the string in my teeth and thus actuate the secondary system which is incapable of wrapping.
Note that this configuration makes me pretty drag proof. If my hand separates from the basetube for any reason it's a REAL good bet I'm off tow.
Note also that I'm also pretty well covered in the event of the thermal center punching scenario you described - much better, if fact, than you were.
Several more comments on that...
- You speculate about going up like a rocket and maybe pushing out a little to try to break the weak link? Nah, I think I'll just twist my hand and wing it from there.
- Generally speaking, I get a little uncomfortable hearing the terms "lockout" and "weak link" used in close proximity to each other.
- Nature can screw you over royally. It can totally make hash out of your best laid plans and overwhelm the best equipment and systems in the world. My feeling is that the best defense against this is a few well placed wind socks.
- Also, with a little bit of room for gray area, I don't like discussions about jeopardizing the tug pilot. Basically - you're each responsible for what happens on your respective ends of the towline and no more.
Contrary to popular belief, there's no such thing as a weak link capable of sustaining a glider's tow that can protect a tug from getting stalled out or driven into the ground. That's what his release is for. That's how come the Aerotowing Guidelines state:
3) The tug must employ a release that can be activated without releasing control.
In a sane world they'd say the same thing with respect to the glider.
With respect to your gauge going 'round the clock incident...
- I would think that you'd want a gauge which only went a little higher than your strongest anticipated weak link and pegged.
- You seem to be making my main point for me. The pilot - correctly it seems - determined that being off tow right after the gas pedal was stomped would have been a bad thing and stayed with it as long as possible.
Let's assume that there's no way to configure a release for that type of towing that can be actuated without letting go of the basetube.
So his 0.8 G weak link made the decision for him - at about the right time, it seems.
If he had been using some specific lower rating - let's call it 0.5 for the sake of argument - it would have failed at the precise moment he didn't want it to and the results could have been ugly.
I believe his reaction would have been instinctive for any pilot in the least qualified to tow - or even free fly for that matter.
So given that a 0.5 G weak link coulda killed any pilot in that situation do we really wanna be scaling the weak link to the experience level of the pilot?
So if the 914 can only pull .5G, then why in Heaven's name do you need a 1.4G weaklink?
That's the power it can deliver. That's nowhere remotely near the tension surges with which you hafta cope if you wanna get up on a good day.
Nice that you've got a good place to aerotow with good dollies and all...
Yeah, manna from heaven. Nice airport, nice grass strip, a tiny bit over an hour away...
I'm also thinking that any turf from which Dragonflies can be safely and efficiently operated is dolly friendly as well. And if you're gonna invest in a dollies I'm thinking that good ones aren't any more expensive than bad ones. And it just takes one nasty incident for a good dolly to pay for itself many times over.
No, I still don't feel I've heard of any AT accident which would have had its severity magnified by a 1.4 G weak link. But I try to keep an open mind and I'm always delighted to get accounts of incidents.
Here's where we definitely have some common ground - We both think there's something very wrong with the SOPs.
- You think 2.0 Gs max is way too high. I think 0.0 Gs min is way too low.
- We've at least got a razor thin point of latitude upon which to negotiate.
- 0.8 Gs seems to be right where you want things for ground based or aero tow.
- That's the absolute bottom of the range the FAA specifies as being safe.
- That's around the middle of what Dr. Hewett seems to be shooting for in his Skyting Criteria.
- Since the USHPA doesn't specify a bottom, that's a little less than the middle of their range.
I could live with a 0.8 G aerotow weak link if I thought that a 0.8 G link stayed a 0.8 G link throughout the tow. I could work around that by testing somebody's loop after he landed and saying, "Hey buddy. You were flying with a 0.5 G weak link. You were out of compliance with the relevant USHPA SOPs and therefore operating illegally with respect to FAA Exemption 4144."
I won't campaign to lower the 2.0 max 'cause I think the FAA knows what it's talking about but, for the sake of argument I could see coming down to 1.5 or 1.4 if we can agree on a solid floor of 0.8.
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Want to buy (WTB) Weak link tester
Tad Eareckson - 2008/10/29 21:17:17 UTC
6736
Correction: You (Larry West) hold the wrench and turn the knob.
I decided I'm gonna put another unit together anyway - you can take it or not, time is not an issue, and you've got first dibs.
I've already got the expensive and messy stuff out of the way, all I've gotta do is cut a couple of short sections of two by four, do some measuring and drilling, and stop by the hardware store.
My plan would be to send you everything 'cept the longitudinal two by fours. All you'd have to do is cut a reasonably straight eight footer in half and drill a few holes for which you will have templates.
My own rig incorporates a triple block and tackle system and a jam cleat which allows me to quickly and easily take the slop out of the configuration to be tested and pre-load it to two hundred pounds or more. Saves a lot of knob and wrench time but for the purpose with which you seem to be concerned the bare bones job should be fine.
And I plan on drilling pilot holes to handle all the deluxe stuff so if you ever wanna upgrade and/or double the capacity all you'll hafta do is enlarge the holes and bolt in the hardware.
Continue on Weaklinks thread (Post 6737)...
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Tad Eareckson - 2008/10/29 21:17:29 UTC
6737
Continued from WTB thread (Post 6736)...
The bridle is ALWAYS gonna be evenly loaded - save for negligible irregularities resulting from friction between it and the tow ring.
Just to make sure you understand - The shorter the bridle the wider the angle and the more load on the weak link.
If the bridle is ridiculously long the apex angle is negligible and you pretty much get just half the tow tension on each end.
As the bridle gets so short that the angle approaches 180 the tension approaches infinity.
1.28 Gs is just fine. I rounded your weight up so you're actually 1.32. Close e-freakin'-nough. The FAA specifies a safety latitude spanning 1.2 Gs - it's just not that critical.
On the high end you need it to break before your glider does. Your glider's good for something in excess of half a dozen Gs. Don't sweat it.
On the low end you don't want it to fail for no reason or at a time when the failure is gonna endanger you.
The main problem with the AT culture is that people don't seem to understand that an untimely weak link break has the capability of getting you killed.
My tows have been pretty consistent and so far my weak links have seemed to go at times that weren't the result of being out of position... the weak link had just been worn down and finally snapped. My question is... when should you replace a weak link, if at all? It seems silly to just let the weak link eventually snap due to wear, considering the time spent + cost involved for those towing who waste a takeoff. Do any of you try to replace your weak link on a regular basis?
Kevin Carter - 2008/10/28 02:09:26 UTC
...Weak links should never break in normal towing, unless the conditions are very strong.
One pilot in the Texas Open had three premature releases in a row with glider damage on all three and different degrees of pilot injury. I myself have had a low level release that caused minor injury.
Can I get some more details on those? In particular, were those weak link breaks, release malfunctions, or both. If malfunctions - what was going wrong?
Kevin Carter - 2008/10/28 23:10:52 UTC
Tad, the pilot with three in a row was not using proper technique. Popping (HARD) out of the cart, then not pulling in enough. He tested fate and finally pounded hard enough to make his glider not flyable. It was extreme, an image I won't forget for a long time.
He didn't need or want them to break - at what I'm guessing was no more than two thirds of a G - and he shouldn't have been punished for jerky towing by getting hurt and having his glider trashed.
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Anurag Sharma - 2008/10/30 11:47:02 UTC
6740
Dear all
as a sailplane and pg pilot the max weaklinks i remember at my sailplane club is 1.2 the all up (they range from a little under 1 to a max of 1.2 times). i believe we follow the same regs as do clubs in the uk from where our indian rules are generally derived.
the sailplane mfrs also quote and supply the proper rated weaklinks and spares for their own gliders. these are generally machined and anodised/coated metal strips with bolt ends and proper radius at the ends and protected in a sleeve against abrasion a bit like the universal tester test specimens defined in astm standards for testing metals in tension.
regards http://www.live.com/?scope=video&form=MICOAL
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Tad Eareckson - 2008/10/30 22:59:44 UTC
6741
Gee, if only you were an HG pilot as well we'd have about as broad a perspective as we could get.
I'm pretty sure you're describing the Tost weak links:
The full assembly is rather heavy. I don't know if that would present problems in some ground based towing environments but Vento seems to have had excellent results with them.
I think they'd be fine on the ends of an AT tow line.
Can you give us a feel for the percentage of sailplane tows in which a weak link (or tow line) break is experienced?
Thanks very much for your input.
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Anurag Sharma - 2008/10/30
6743
sorry i have only 1 trial beginners hill hg flight (prefer pg)
in fact i wasnt.
i was describing the L23 super blanik all metal (LET czech republic - same as the russian? ) weaklinks. since that is the training and L33 is the solo plane we generally use in india nowadays .composite craft are very difficult to maintain in indian climates
we stopped flying the antique wood and fabric grunau baby and british T21 Slingsby sailplanes on which the tost release was used after a wing folded up on tow and resulted in a fatality quite a few years back 1993 0r 4 was it?
this uses a y bungee cord at the end and two half circle (spoon shaped) strip release at both sides (cg) . the tost release is still there for some for aerotow but mostly its diesel winch launch
the weaklink construction is similar only there is no hole in the middle (the width is accurately determined per batch for manufacturing which obviates the need to reduce the c/s area by trials ).
i can remenber only 1-2 weak link breaks/year in the past few years generally due to mishandling the transition or pulling too hard generally the latter
the steel multistranded twisted cable (2.5 tons nominal breaking) generally starts to give way after 900-1200 lauches due to abrasion and necking but can be spliced for a maybe a hundred more launches at most after which its a waste of time (vs launch rates).
hope this helps.
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Donnell Hewett - 2008/11/05 21:23:39 UTC
6744
I am sorry I have not been able to participate in the discussion on weak links that has been raging during the last few weeks, but I have been too busy to even read the postings much lest respond to them until now. Let me begin by saying that I personally appreciate Tad Eareckson's efforts to improve the SOP of aerotowing as well as his suggestion to update the Skyting Criteria. It is through efforts like his that progress is made toward safer towing.
Rather than address his and other's comments made during the recent discussion on weak links, let me remind folks that the Skyting Criteria were not developed as a model of a practical towing system. They were proposed for the purpose of defining what an ideal towing system should be in order that towing would be as safe as free flight. The first four criteria are intended to make towing accurately simulate free flight, the next four are to guarantee a safe transition to and from tow, and the last four are to identify some of the safety requirements of practical implementation.
One should remember that no towing system meets all twelve criteria all of the time. Therefore, the purpose of the Skyting Criteria is to help identify when a particular system is deviating from the ideal so that one knows when to be extra cautious and when to make compensations for those deviations.
For example, in the case of aerotowing the second criterion is accomplished by speed control rather than normal tension regulation. As long as the tug and the glider are flying at the same speed the tension remains constant. In general, this speed regulation works great as long as the air is smooth and the two pilots properly cooperate. But anything that causes a differential speed between the two craft will cause the tension to fluctuate, sometimes quite rapidly. Fortunately, the fluctuations are usually quite temporary and rarely reach the excessive values encountered in other forms of towing (such as when a payout winch jams or runs out of line). Nevertheless, compensation must be made for aerotowing's inability to meet criterion two under typical aerotowing conditions. Making the towline longer or more elastic only exasperates the differential velocities, and making it shorter increases the violation of criterion one. So the only practical solution is to recognize that the violation exists and learn to live with it. (I.e. gain sufficient practical experience under a qualified instructor to handle typical thermal conditions and to know instinctively when to release from tow as soon as the situation warrants.)
Now regarding weak links, the whole purpose of a weak link is to release the pilot from tow when he cannot do so himself and the towline tension continues to rise above the limit of safe towing. What that limit is, depends upon many factors, including pilot skill and experience as well as the type of towing and the system being used. I believe everyone recognizes that "one size weak link simply does not fit all".
For example, in the case of an ideal towing system, where the horizontal tension remains constant, a weak link of 0.5 gee will allow the glider to climb at a 30 degree angle, a 1-gee weak link will allow a 45 degree climb angle, and a 2-gee weak link will allow a 60 degree climb angle. These are also the angles a pilot will find himself flying in free-flight when the weak link breaks. Personally, I am not convinced that all hang glider pilots are qualified to recover safely from such extreme aerobatic attitudes. That is why I still recommend a 1-gee maximum weak link when towing horizontally with a good tension controlled system.
However, in the case of aerotowing, where the towline tension may vary as much as +/- 0.25 gee (or even +/- 0.5 gee) when taking off on rough or grassy terrain or when entering and leaving a strong thermal, a 1-gee weak link is going to be breaking much more often than it would on a well-regulated tension system. For most forms of towing, excessive weak link breaks usually constitute nothing more than a minor inconvenience (or a major nuisance). They simply are not a safety issue at all.
However, aerotowing also tends to violate Skyting Criteria twelve (a suitable environment) by frequently towing over terrain that is completely unsuitable for landing. In this case, a weak link break is considerably more than a minor inconvenience. It potentially places the pilot in an extremely dangerous and possibly fatal situation.
Yes, the general rule of towing is, "Get off line at the first sign of danger." However, there are exceptions to this general rule. In fact, I am sure you can imagine more than one situation where getting off line is the worst possible alternative you can take. In such cases, the towline becomes a "lifeline" rather than a "death-line." It pulls you out of danger rather than plunging you deeper into danger. Releasing low over unsuitable terrain is an obvious example of this exception.
Once again, the recognition that aerotowing frequently violates one of the Skyting Criteria requires an appropriate compensation in order to be as safe as possible. In this case, one must use a weak link that simply will not break under reasonable flight conditions and typical flight situations. When one also considers the typical tension variation encountered when aerotowing hang gliders, the conclusion is that the aerotowing weak link should be designed to break in the neighborhood of 1.5 gee (or at least somewhere within the 0.8-gee and 2-gee range specified by the FAA for towing sailplanes).
One also concludes that an aerotow pilot flying with such a weak link should have the skills to recover safely from aerobatic maneuvers greater than 45 degrees - because that is what he may well encounter when the weak link does break.
I believe that the first of these two conclusions is perfectly consistent with the point that Tad has been trying to make. And I thank him for keeping this issue before the hang gliding community.
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Tad Eareckson - 2008/11/06 16:13:36 UTC
6745
Donnell,
While I still maintain a couple of minor points of disagreement - CLOSE ENOUGH! Can I get a framed, autographed copy of that post on
acid free paper?
I believe everyone recognizes that "one size weak link simply does not fit all".
I wish.
Over the course of the past couple of seasons I've been able to batter my local crowd down enough to get a few 1.4 jobs in the air but at the flight line if a 320 pound skygod glider asks for a weak link he gets the same loop of 130 pound Greenspot as a 200 pound first time soloer.
If the big guy puts the link on the end of his two point bridle he's got about 0.76 MAX and practically something that is very likely to break at 0.4.
If the new chick puts it on her two point, she's got a solid 1.22. After she gets better and starts towing off of her shoulders she gets 1.4.
Here is the requirement from the 2007 Worlds local rules (which I wrote) for weaklinks:
Weaklinks
Pilots must use weaklinks provided by the meet organizers and in a manner approved by the meet organizers. All weaklinks will be checked and use of inappropriate weaklinks will require the pilot to go to the end of the launch line to change the weaklink.
Weaklinks will consist of a single loop of Cortland 130 lb Greenspot braided Dacron Tolling line http://www.cortlandline.com/catalog/braid.html and should be placed at one end of a shoulder bridle. The tow forces on the weaklink will be roughly divided in half by this placement. Pilots will be shown how to tie the weaklink so that it more likely breaks at its rating breaking strength.
Yeah, why consider glider weight at all. Next...
We need to codify a lower limit to give people a tool with which to protect themselves from kind of crap - which, by the way, is very much alive and well in the US too.
Personally, I am not convinced that all hang glider pilots are qualified to recover safely from such extreme aerobatic attitudes.
They may or may not be but - again - even a 0.8 (or less) G weak link may be of no use whatsoever in preventing an aerobatics champ from doing a steep wingover into terra firma. He can easily find himself in a situation in which his release is his only option.
That is why I still recommend a 1-gee maximum weak link when towing horizontally with a good tension controlled system.
Fine. Peter seems to think that 0.8 presents no problem. I yield the floor to the winch crowd. From what I understand of tension controlled towing I would imagine that you'd REALLY want to be off tow if the tension climbed that much.
In fact, I am sure you can imagine more than one situation where getting off line is the worst possible alternative you can take.
An instance where the weak link could have broken and I'm glad it didn't...
I had the Axis on the cart with the AOA a bit high, launching to the west, with a moderate 90 degree cross from the left. I came out of the cart rolled and yawed to the right with the upwind wing flying and the downwind wing stalled. It was rather dramatic. If I had released or if the weak link had broken, the downwind wing would have further stalled and I would have cartwheeled into terra firma in an unpleasant fashion. I held on tight gaining airspeed until the downwind wing began flying, got in behind the tug, and continued the flight.
Sunny later told be he was about to give me the rope and I thanked him to no end that he didn't. Lesson learned, check AOA on the cart especially in crosswinds.
---
An instance where the weak link held and it would have been nice if it had yielded...
On another instance, I was towing behind a trike being piloted by Bill Bennett as part of a demo at Fairfield (my sailplane port.) These were the early "experimental" days of aerotow. We were using a center-of-mass tow system, a three-ring circus release, and a fairly short rope. Bill commenced the tow, I came off the cart, and Bill started a rapid climb. This put me below the trike, stalled, and soon into the prop wash and tug wing-vortices. My Axis began to roll to the right, I tried to release but the polypro towline had some slack and the release mechanism held tightly. The line then tightened. I do not remember what kind of weak link was being used but with the mounting pressure I thought for sure it would break; but it didn't. I was rolling past 90 and gave the release one last yank. It released, I completed a wing over just over the tree line, and came in for a nice landing. Bill and I debriefed about the pull-up. The subsequent tow, without the rapid climb out, went okay.
Lessons learned, abandon the three-ring circus and use a decent release (I purchased the then "new-fangled" Wallaby Release) and you can't count on the weak link to get you out of an emergency situation.
Releasing low over unsuitable terrain is an obvious example of this exception.
I think most Dragonflies tow out of airports or more than adequate flight parks and they climb so well that terrain is not an issue 'cause if you pop off early you have - almost by definition - either enough remaining runway ahead of you or enough altitude to turn around and land normally.
In theory the worst thing that could happen to you would be to come down into propwash but I haven't heard of any good examples of this being a serious issue. I got some more info on the Texas Open case I referenced earlier and it seems that this bending occurred as a result of a pilot who was in no way qualified to aerotow getting on the cart.
But the first incident related by Danny - and another very similar recent one at Ridgely triggered by a dust devil - is the reason why I feel no one can safely aerotow below 0.8 Gs.
Danny doesn't weigh anything. If he did he'd have been flying the same loop of Greenspot and thus at a lower G rating and the probability of that thing popping at precisely the wrong moment would have gone WAY up.
The nice thing about dolly launching behind tugs is that you can release without moving your hand, in the case of two point - significantly or, one - at all.
I've developed an excellent AT release system in which I have total confidence. The pictures are up at:
and I'm helping a friend refine his really nice slap-on concept. I hope to have photos of it up in a few days.
The better your release system the less you think about the weak link as something that's gonna keep you out of trouble.
I can't thank you enough for the time and thought you put into these posts and for your comments regarding my efforts. I think they'll be most valuable in helping to get us to clean up our act. Definitely worth waiting for.
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Jim Gaar - 2008/12/02 18:23:16 UTC
6751
Lessons learned, abandon the three-ring circus and use a decent release...
The lesson learned should have been to buy a LinKnife, a MUCH better and safer choice...
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Tad Eareckson - 2008/12/04 03:16:36 UTC
6752
Apologies for disappearing for a month and not responding to a couple of posts. Been having an epic knock down drag out weak link "discussion" on the local forum. 226 posts to date and still much ground to cover.
So much for:
I believe everyone recognizes that "one size weak link simply does not fit all".
and the understanding that waiting for your weak link to break in a low level lockout is not a sustainable survival strategy - fatality reports that indicate the opposite don't seem to make any difference.
Anurag,
Thanks very much for the information on the Blanik weak links. I was previously unaware of any commercial stuff other than Tost.
Thanks also for giving my a feel for what's going on with the sailplanes with respect to this issue.
Stuart,
Paragraphs 6 and 7 of your last in this thread were gems. I'm very happy to have them in the arsenal I'm using to battle evil.
Larry,
Bad news and good, respectively...
I've got a second tester assembly just about complete but it's been an enormous time killer (good chunks of several days) and I'm not feeling real inclined to part with it for a figure that wouldn't make most folk gag.
The good...
I wrote Harrier Fluid Power and they thanked me and moved the decimal point over on the price of that pressure gauge.
If you ever wanna go from scratch yourself lemme know and I can send you sources, plans, and templates.
And, of course, if you or anyone else wants anything tested up to 776 pounds just send me the materials and I'll be happy to do it for free.
And I've got another rig that'll give you a reasonable idea up to 2000 pounds.
Peter,
If you fail to hook in you want the weak link to break but I prefer to make sure I'm connected to the glider 'cause I'm not wild about being in that situation anyway.
If, however, you pitch off the cart...
I know about this type of accident because it happened to me, breaking 4 ribs and my larynx... and I was aerotowing using a dolly. The shit happened so fast there was no room for thought much less action. But I wasn't dragged because the weaklink did its job and broke immediately on impact.
the weak link WILL break but you actually don't want it to. You want the tug to drag the glider so it's moving forward as fast as the topsoil will allow to make things less traumatic when you swing into the keel.
Jim,
I've thought quite a bit about the Linknife with respect to aerotowing and concluded that it offers no advantage over other approaches that don't require cutting and replacing string each flight.
The Linknife is great if you're gonna configure it somewhere remote at the other end of a long lanyard - a la between the tow line and the apex of a closed two point bridle.
But if you put it there you hafta take your hand off the basetube to actuate it.
Imagine if you will, just coming off the cart and center punching a thermal which takes you instantly straight up while the tug is still on the ground. Know what happens? VERY high towline forces and an over-the-top lockout. You'll have both hands on the basetube pulling it well past your knees but the glider doesn't come down and still the weaklink doesn't break (.8G). So you pull whatever release you have but the one hand still on the basetube isn't enough to hold the nose down and you pop up and over into an unplanned semi-loop. Been there, done that... at maybe 200 feet agl.
So you pull whatever release you have but THE -ONE HAND- STILL ON THE BASETUBE ISN'T ENOUGH TO HOLD THE NOSE DOWN AND YOU POP UP AND OVER INTO AN UNPLANNED SEMI-LOOP.
Smoking freakin' gun.
You do that at something less than 200 feet - you're gonna die.
And if you DON'T center punch the thermal - it could get even more interesting.
You could mount the Linknife on the keel with an opening bridle configuration but - why bother? My remote barrel setup:
The bridle wrap "problem" is a non issue. If a secondary weak link doesn't set you loose you can lose the crap by relaxing your bite.
If you wanna stop killing AT people you don't do it by dumbing down weak links. You do it by configuring the release such that the pilot doesn't have to make a choice between getting off tow and flying the glider.
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Larry West - 2008/12/05 14:23:52 UTC
6753
Thanks Tad
Until I have funds or motivation, we bought a bunch of Stu's "known" weaklinks and tested them with our knots on the rig itself. It wasn't as easy as using a dedicated tester, but we now have three bags of weak links we trust will break at 300, 250, and 200 pounds and that covers the pilots we have involved in truck towing right now. Our trucks engine threw a rod bearing last weekend, so we're down for a little bit. Man, we've gone through 3 trucks with this one winch. Wish the trucks were as durable as the winch.
I would like to see your plans and vendor lists and keep any eye on prices for a while
Thanks again
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Tad Eareckson - 2008/12/08 17:21:07 UTC
6757
Larry,
Yeah, people who never test weak links never realize how much of a pain it is to actually test weak links - dedicated tester or not.
One of these days I'll get around to photographing my rig so's duplicating it will be less of a nightmare.
Sorry to hear about the engine. As per above it always seems to be a lot harder and more expensive to get gliders up than it looks on paper.
Gregg,
I've done a LOT of work, study, and discussion on the interwoven issues of AT releases and weak links and reached a lot of ironclad conclusions I can back up with reams of data.
Using Dragonflies and launch dollies to get gliders aloft is incredibly idiot resistant. That combination alone makes the accident rate so low that trends are hard to spot.
If you eliminate the dolly you automatically open a very large can of failure to hook in, blown and uncontrolled launch, and release accessibility worms.
The next most stupid thing you can do is use a release which requires you to remove a hand from the basetube.
Peter Birren - 2008/10/27 23:41:49 UTC
So you pull whatever release you have but the one hand still on the basetube isn't enough to hold the nose down and you pop up and over into an unplanned semi-loop. Been there, done that... at maybe 200 feet agl.
The lockout Lauren mentioned was precipitated by my attempt to pull on more VG while on tow. I have done this before but this time the line wouldn't cleat properly and while I was fighting it, I got clobbered and rolled hard right in a split second. There was a very large noise and jerk as the relatively heavy weak link at the tug broke giving me the rope. I recovered quickly from the wingover and flew back to the field to drop the line and then relaunched after changing to a normal weak link. I have never had a lockout situation happen so quickly and dramatically and had no chance to release as I have always thought I could do.
(Paul was towing one point with a barrel release or two and a 1.4 G / 420 pound weak link on his end.)
I have/had heard from both Peter and Paul that reaching for a lanyard or barrel was no big deal. And it never is - until you find yourself in a critical situation in which you REALLY NEED TO. Then it's damn near always a HUGE freakin' deal. And I have no doubt whatsoever that it's been a huge enough freakin' deal to spell the difference between life and death for folk like Rob Richardson and Mike Haas.
Incident 1
On June of 2008 during a fast tow, I noticed I was getting out of alignment, but I was able to come back to it. The second time it happen I saw the tug line 45 deg off to the left and was not able to align the glider again I tried to release but my body was off centered and could not reach the release. I kept trying and was close to 90 deg. All these happen very quickly, as anyone that has experienced a lock out would tell you. I heard a snap, and then just like the sound of a WWII plane just shut down hurdling to the ground, only the ball of fire was missing. The tug weak link broke off at 1000ft, in less than a second the glider was at 500ft. At that point I realized I had the rope, so I drop it in the parking lot.
IF YOU LOCK OUT TO THE LEFT YOU CAN'T REACH THE RELEASE?! AND FLIGHT PARKS ARE ALLOWING PEOPLE TO LAUNCH WITH THIS CONFIGURATION?! (But God help anyone who get's on the cart with a 1.4 G weak link.)
Ever notice that NOBODY who's launched with a finger on the trigger configuration has EVER been killed or hurt?
So why do we continue to tolerate the other crap?
Aviation is all about decision making and control. If you can't implement the control, the quality of the decision making doesn't do you any good.
And to the subject most directly at hand...
In this neck of the woods we are towing solo gliders ranging from 200 to 350 pounds. ALL of them - bottom to top, two point and one - have been told that a single loop of 130 pound Greenspot on an end of whatever bridle of whatever material they're using will have them limited to 1.0 Gs tow line tension.
VIRTUALLY ALL OF THEM BELIEVE THIS!
Virtually none of them has any idea what the actual weak link breaking strength is or how to calculate how that translates to G loading.
However, virtually all of them will fight to the death rather make the slightest alteration to what they have been taught by their instructors is the perfect weak link for everyone. The 350 pounders will no way in hell allow a single pound of increase as the 200 pounders will no way in hell allow a single pound of decrease.
And virtually all of them believe - despite the absolute and total logical disconnect - that the flimsier a weak link is the safer it is, regardless of all the broken downtubes they've experienced.
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 80 to 200 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 Pilot's Operating Handbook. Considering the possible flying weights, this ranges between 95 and 160 percent which is a narrower range than specified in the FARs.
Makes me wonder if we should be using Tost weak links instead of old bits of rope.
We've spent over thirty years trying to reinvent the goddam sailplane. We didn't need to. All we had to do was LOOK at what they had figured out many decades before we existed.
Sailplanes have ALWAYS known that you use a ground towing weak link no more than equal to the one you use for AT and that you probably want to beef it up when you get behind a tug. Hang gliders have always taken the PRECISE OPPOSITE approach.
Donnell's always been one of my biggest heroes in this sport. But he's come out of a background in which crappy releases, actuation systems, procedures, gliders, tugs, and other peripheral equipment have reigned supreme and foot launching was the norm. Maybe in that kind of chaos you ARE better off dumbing down the weak link. But the landscape has changed.
Most people ELECT to totally disregard the Skyting Criteria and USHPA SOPs but you don't tailor policy to accommodate them. Darwin had some pretty good ideas on this front.
You simply cannot tune the weak link to compensate for pilot incompetence. If you try you may or may not LUCK OUT one or two times. The third time YOU WILL KILL somebody who had no business being alone on the end of the rope to begin with.
Note that the Nimbus Pilot's Operating Handbook says nothing about scaling weak link strength to pilot skill level. The weak link is there only to protect the sailplane - not the person inside. 600 KG for EVERYONE.
Weak links protect your aircraft against overloading.
That's it. That's all they can do.
The current USHPA SOPs require AT weak links to fall within the range of 0.00 to 2.00 Gs. I hope by now everyone who's generating an occasional brain wave sees a BIG problem with that.
The FAA says 0.80 to 2.00. That's obviously a big improvement but - as I've said before - I think you're asking for trouble pushing that bottom end and I see no plus to pushing the top either.
The Nimbus says 0.95 to 1.60. I'm getting A LOT happier with that.
We've got a seriously broken system now. Nobody complies with the REQUIREMENTS we now have on the books to which we are SUPPOSED to be adhering to permit us to tow under the terms of FAA Aero Tow Exemption #4144. Whenever, for example, some piece of crap like the one Carlos had velcroed to his starboard downtube goes up, we are, in fact, in flagrant violation of the law.
We need to start growing up and cleaning up our act.
The first thing we need to do is put a bottom limit on weak link strength in our Standard Operation Procedures. The best model says 0.95, I say round it 1.00 which is what everybody thinks he's using anyway. But we need SOMETHING at an ABSOLUTE MINIMUM of 0.80 and we don't need it now - we need it fifteen years ago.
Then we need to start enforcing what's on the books.
I hope I'll be hearing from you before too long?
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Jim Gaar - 2008/12/08 21:51:59 UTC
6758
The below quote is simply NOT TRUE Tad. I've routed the pull string through a number of places on the corner of the control frame and with a loop around my fingers I can release with a quik slide of my hand-never leaving the basetube...same as the LMFP AT lanyard release.
I can't believe that when ATing the wing will hit a thermal without having the tug fly through it as well. Not a great example again. It's possible but not very probable.
But if you put it there you hafta take your hand off the basetube to actuate it.
*
Tad Eareckson - 2008/12/09 00:00:52 UTC
6759
Jim,
If you're talking about using the Linknife to cut a string between the tow line and the apex of a closed two point (pilot and glider) bridle - I may or may not stand corrected.
But it sounds to me like you've got the Linknife up at the top end of an opening bridle at the keel.
If the former I'd be surprised if you could be assured of maintaining full and constant control while taking up the slop that's dictated by that configuration.
If the latter - fine. I'm totally OK with that. But I can do the same thing just as reliably without cutting, tying, and replacing each flight.
With respect to your second point...
Yeah, most of the time you can see it coming. And up high it doesn't matter - from a safety angle - whether you see it coming or not. But even just off the cart dust devils can and do sneak through and they're deadly and you've got to design and configure and be prepared for them.
We've already got Peter's account of being blown out of control just off the cart by a thermal that apparently gave no warning.
Last summer Bob Koshmaryk - one of our Ridgely people - got dust devilled, dragged a tip, oscillated, and released a la textbook.
2006/02/05 John Dullahan - one of our locals - was at Quest and got hammered at ten feet by a black hole behind him. Aside from having a brake lever on the starboard (high) downtube he did everything right and as fast as humanly possible and still got a broken wrist out of the deal.
In none of these situations do you want to have anything cutting into your safety margin - even if you haven't had any problems with the stuff you've been using in your previous thousand tows.
Sorry, but I simply cannot stay out of this lively discussion on weaklinks.
Why not? There will be tons of other lively discussions on weak links (two words) that you'll stay out of in the coming years. Half a dozen days shy of eight years after this post Zack Marzec's gonna get whipstalled, tail slid, tumbled, and killed as a consequence of the inconvenience of an ultra-safe Infallible Weak Link at best at 0.8 Gs and at the ragged edge of the bottom of the FAA legal range.
Concerning that topic, I am firmly convinced...
Well if you're FIRMLY CONVINCED that should be way more than good enough for the rest of us.
...of the following points:
1. Every towing system, without exception, contains a weaklink. It may be a string or mechanical device deliberately inserted into the towline, the towline itself...
From this point on we're way into fringe activity and don't need to be discussing it.
...the release mechanism, the flying wires of the glider, the pilot's harness (when body towing)...
Rubbish.
...or some other component of the pilot-glider-tug system. But something eventually is going to be the first thing to break. That thing is the weaklink.
2. Of all of these options, the ONLY PROVEN ACCEPTABLY SAFE weaklink is a string deliberately inserted into the towline which consistently breaks at a known and specified tension.
The FAA permits it to be the towline. As far as I'm concerned it shouldn't - but so what if it does? The glider ends up with some rope - as he would in the event of a deliberate front end release - and has the capability of immediately dumping it.
3. The sole purpose and function of this weaklink is to limit the towline tension to a manageable level, i.e. a level such that the pilot can still maintain control of the aircraft in the event that the weaklink breaks.
Absolute total bull fucking shit. Unadulterated lunacy.
Here's the sole purpose and function of the weak link in the discipline of towing that you DIDN'T pull outta your ass all by yourself and present as a universal truth:
Tost Flugzeuggerätebau
Weak links protect your aircraft against overloading.
Doesn't say SHIT about manageable levels of control.
And for all practical purposes an overload situation doesn't occur until a fair bit after things have gone totally tits up. It's no more a component for maintaining control than a helmet or parachute is. And it's no more of an assurance that things will end well than a helmet or parachute is. Try reading AND THINKING ABOUT two or three towing fatality reports.
4. The appropriate strength of a weaklink depends upon pilot skill.
See my "bull fucking shit" comment above.
A skillful pilot can maintain control when a stronger weaklink breaks whereas a less skillful pilot cannot.
You mean the same skillful pilot who was unable to maintain enough control on the tow during which nothing else noteworthy was going on? He can't manage to keep the glider behind and pointed at the tug but after he locks out and instantly loses several hundred pounds of towline tension he'll be just fine? Hell, maybe hooks the dust devil and climbs out on it.
As a general rule, a beginning pilot should limit his towline tension to 1/2-g and an experienced pilot to 1-g.
Weaklinks of 140 and 200 pounds will be available and provided by the organizers. Weaklinks provided by the organizers must be used by the competitors.
general rule?
Only highly experienced pilots qualified to perform aerobatics while on tow should use a 2-g or stronger weaklink while being pulled forward (such as when aerotowing).
- A stronger than two G weak link for aero has ALWAYS been a violation of u$hPa's agreement for operation under the terms of Exemption 4144. And five months ago the FAA pulled hang gliders in to be covered under their sailplane regs AT which have limited the weak link to 2.0 since the beginning of time.
- Why the fuck would any halfway sane person wanna fly over 2.0 even if the rest of the system could handle it fine anyway. For me that's 650 pounds of thrust if I'm pointed at the tug or 650 pounds of lockout tension if I'm not. If I can't bring it back before exceeding 650 pounds I'm not gonna be able to bring it back. And if the shit's happening low I'm not gonna be able to survive. And I can do all the aerobatics skills involved just fuckin' fine, thank you.
- Here's some more of what the 2019 Big Spring Nationals rules say:
1. Must be a current USHPA member. Foreign pilots must obtain a 30-day temporary USHPA membership.
2. Must have a pilot proficiency rating of H3 with Aerotow (AT) special skill rating or foreign equivalent (IPPI card). H2 for Sport Class with permission from the meet organizers.
3. Must have aerotowed with the glider that he/she is flying or similar at least ten times. Practice tows will be available onsite on Saturday before the first competition day.
4. Pilots under the age of 18 must have a parent (or guardian) written consent (notarized) to participate in the competition.
So a fourteen year old little girl Hang Two can show up with her baby bladewing at 180 pounds flying weight and zero towing experience of any flavor and take her first practice hop pro toad with a four hundred pound towline weak link. And people have zero problem with that.
And compare/contrast with the international outrage that erupted when T** at K*** S****** put Paul Tjaden up on the same weak link and it didn't work when it was supposed to.
5. The appropriate strength of a weaklink depends upon the type of towing system used.
No it doesn't...
Dr. Trisa Tilletti - 2012/06
If tandem operators think that, practically, a 520 lb. double-loop weak link is too much for a tandem, it is way too much for a solo pilot.
It depends entirely on the opinions of the brain dead total douchebags running the tandem thrill ride operations.
Different strength weaklinks should be used for foot-launched ground towing, platform towing, aerotowing, boat towing, etc. As a general rule, forward pulling systems such as aerotowing, foot-launch ground towing, etc. should use 1-g weaklinks or less. Consistently downward pulling systems such as platform launch can go as high as 2-gs.
As a general rule this is all total bullshit. We don't need or want weak links when things are pulling CONSISTENTLY - 'specially when they're consistently pulling forward or some reasonable mix of forward and downward. Assuming you've gone up on some piece o' shit Easily Reachable Reliable Release - which you undoubtedly HAVE (or you wouldn't be writing all this total crap about weak links) - you want the Infallible Weak Link to do your job for you when they're pulling SIDEWAYS. And it doesn't matter whether you started out or intended to be having a forward or forward plus downward pull.
6. The appropriate strength of a weaklink does not depend upon weather conditions or the flight attitude of the glider (turbulence, wind gradient, lockouts, etc.).
Bull fucking shit. A weak link needs to be able to handle all the weather conditions, turbulence, flight attitudes imaginable while there's a snowball's chance in hell of the tow being sustainable. And we don't use "weak link" and "lockout" in the same sentence 'cause you can be in a lockout that's gonna end upon impact and your death at the same half a G you might need to stay alive in more commonly encountered circumstances beyond your control.
It is impossible to design a weaklink to release the pilot when he looses...
Loses.
...flight control because there is no correlation between towline tension and flight control.
Which totally contradicts all the drivel you've spewed up to this point.
(A pilot may be in perfect control under high tension but out of control under low tension.)
But a highly experienced and skilled tow and aerobatic pilot who's out of control under low tension will instantly regain full control without losing more than an inch and a half of altitude once his Infallible Weak Link increases the safety of the towing operation. So three choices:
- use much safer Infallible Weak Link that succeeds under very low tension
- continue the out of control tow until adequate higher tension is achieved
- accelerate the out of control tow in order to achieve the adequate higher tension faster
A weak link can only be designed to release the glider under the worst possible conditions before the towing forces exceed the limits of safe recovery when the weaklink breaks.
This is getting too demented and delusional to even try to respond to. But do keep it up, Donnell...
Hewett's point 7 is about the best analysis of towing and the relationship to weak links that I have ever read anywhere.
You're almost up to Point 7.
7. The appropriate strength of a weaklink should always be tested on the ground, not in the air.
Fuck that. So much easier and more effective to give your opinion on its appropriate strength.
Rob Kells - 2005/02
Aerotow Release Attachment Points for Wills Wing Gliders
Always use an appropriate weak link with a finished length of 1.5 inches or less.
It's been working for Wills Wing close to a decade and a half at this point. Besides... Name one individual in the history of the sport (with the possible exception of T** at K*** S******) who's ever presented a case for using a weak link with an inappropriate strength.
For example, if a weaklink is tested on the ground to consistently break at 1-g, then you can be certain it will do the same thing in flight.
And will obviously keep you from getting into too much trouble. If it did it wouldn't be appropriate. Problem solved.
Therefore, if this ground-tested weaklink keeps breaking inconveniently while aerotowing, you...
...assuming the inconvenience hasn't been too severe and that you're still alive at this point...
...can be certain that the problem is not the strength of the weaklink.
Nah, it's obviously your shit flying skills and technique.
The problem is with something else concerning the towing system, the flying technique...
See? Toldyaso.
...or the flight conditions.
Like soarable. What kind of total fucking moron would go up in actual thermal conditions with an appropriate weak link with a finished length of 1.5 inches or less?
For example, if there is enough thermal activity that the tug and glider enter different air causing the towline to go slack, then there is also sufficient difference in the air to cause the towline to tighten and the tension to increase rapidly.
One shudders to even think about it. Let's check the Skyting Criteria to get straightened out on this issue...
Donnell Hewett - 1985/08
12. SUITABLE ENVIRONMENT
The system must be operated only within the environment and under the conditions for which it was designed.
Thermal conditions, Infallible Weak Link. Gotta be pretty wacko to rank that as an option.
Also we have:
2. CONSTANT TENSION
The tension in the towline must remain essentially constant throughout every phase of the towed flight.
I DEFY anyone to even TRY to maintain Constant Tension when the cumies are starting to pop. Total crap shoot.
Unless there is sufficient stretch in the towline to allow a skilled pilot time to compensate for this rapid increase in tension, it will quickly increase beyond the weaklink breaking point even while the pilot is in perfect control.
And these assholes are using SPECTRA!!! Can you even begin to IMAGINE? And they won't even swap in poly for the pussy muppets.
If the problem is a lack of stretch of towline, the system needs changing.
Did you ever consider for a nanosecond the stretch we have courtesy THE AIR IN WHICH WE'RE OPERATING, payout winch brake resistance, line sag, glider flex?
If the problem is flying technique, the pilot needs more training.
Show me a video of a pilot breaking weak links because of his towing technique.
If the problem is excessive air turbulence, flight operations need to be suspended.
"Way too soarable guys. We're gonna shut down until an hour before sunset when the towing quality conditions start to peak."
Simply switching to a stronger weaklink does not make this situation better...
Then again, Russell Brown had us double up behind him after six breaks in a row at Zapata. We couldn't figure out why we had so many breaks so quickly. Maybe just coincidence.
...it simply makes things more dangerous when that weaklink does not break and when (not if) it does break.
This is 2005. Dragonfly aerotowing has been up and running on a fairly massive scale in the US and Australia for a decade and a half. Just how far up one's ass does one need to insert his head to be this astoundingly oblivious to what's actually going on out in the REAL world? And ditto for the Peter Show cult member douchebags who are hearing this and not coming down on Donnell like a ton of bricks. And we’ve got Flight Park Mafia assholes like Trisa and Davis just fine with this rubbish.
Remember what I've said about people on glider forums who have their faces prominently depicted on their avatars?
Peter's the foremost example - by far - of the 25 direct posters on the Davis Show Lemmy Lopez thread. (Donnell doesn't post directly.) I'd put Mark G. Forbes:
as a fair second. I'll let Sergey...
...slide 'cause he's not trying to sell himself 'cause he:
- appears to be demoing a harness or sumpin'
- has never tried to sell anybody anything beyond the idea of a sane tow release
Since I have not had time during the last week to respond to your request for comments on the topic of weeklinks...
Way to kick off the response, Donnell.
Do they STILL not have spellcheck software in your neck of Texas? This post is LOUSY with misspellings and the vast majority of them aren't typos. They're the same crap you've been doing for as long as we've been reading you - back to 1981. Stuff that you should've gotten straightened out in grade school.
And I've never liked "weaklink" as one word. It's not and doesn't look and/or feel right. And Davis and Rooney use it as one - along with three point for two point towing.
...until now, I would like to do so at this time. In order to save time and space, I will...
Look at actual aeronautical theory and what's been done in conventional aviation since the beginning of time and help get hang gliding consistent with it? Just kidding. Please do continue.
...insert my comments in blue after the various quotes from your email in black.
This would be so much easier on a non email list server forum.
For starters - The place I finally found religion...
A really unfortunate choice of phrasing - in retrospect.
I tried to access this web site but without success, so I am not quite sure about what religion you found.
Never mind. I can handle it a hundred times better than those Dynamic Flight assholes were ever able to. And besides, I don't actually do religion anyway. Not one of My Priorities.
It took about two years for me to cleanse my mind of all the indoctrination with which it had been poisoned before but when the bulb finally hit full intensity it was blinding.
And even then I wasn't completely out of the woods.
I am sorry it took so long, but I'm glad the bulb finally lit up.
I'm glad you're glad for me. How long's it gonna take for your bulb to light up?
Summary:
The sole purpose of the weak link is to break before the plane does.
- PERIOD
I respectfully disagree with you here.
Who'da thunk.
Any airworthy aircraft can withstand more than 4 g's before breaking up.
Hang gliders are certified to six.
Therefore, a weak link of 3 or more g's would easily break before the plane does.
- NOBODY's asking for three or more Gs. Nobody's asking for more than two. Note the parallel with Rooney here. You wanna get up to legal FAA strength range and consistent with what sailplane manufacturers specify and:
In your book however, anything less than the cable strength of the glider is OK?
Yeah, sorry... nope. Not behind me at least... go be a test pilot behind someone else.
We certainly don't wanna just dial things up half a G and see what happens. What a can of worms that would be with respect to our global hang and para glider towing religion and all of its high priests.
- But we're OK just as long as the weak link doesn't exceed 1.0 Gs. Then one somebody IS totaled while flying one of your Infallible Weak Links we immediately shift the conversation to illustrate what a total crap pilot he was.
- So you've obviously decided to expand your hang glider definition of a weak link to conventional aviation 'cause there's absolutely nothing you're saying that's specific to hang gliders (it's finally occurred to me). In fact you're referring to the hang glider as an "aircraft" while the FAA excludes us under that definition and categorizes us as "air vehicles". So how come conventional aviation hasn't embraced your opinion yet - and where are all the crashes that are supposed to be happening as a consequence of all of them flying 1.4 G Tad-O-Links?
But a 3 or 4 g weak link would be extremely dangerous even if it did prevent both plane and glider from breaking.
- A glider IS a PLANE.
- Name a weak link rating over 0.2 that CAN'T precipitate an extremely dangerous situation when it works.
- But no one would EVER die if the weak link were one G or safer. It would just increase the danger of the situation. And shit... Every time you go flying there's something that increases the danger of the situation - gusts on launch, glider traffic, crosswind on approach, cows in the LZ...
However, you are absolutely correct in recognizing that there is always a weak link somewhere in any and every towing system.
- For AT it's the Dragonfly's chintzy tow mast the motherfuckers started pretending seven and three quarters years ago was deliberately engineered as a redundant tandem weak link.
- There's another more universal sense of the term "weak link" with the same etymology and it's a total negative. The weak link was what was gonna break in your anchor chain and set you adrift to smash up on the rocks. Your whole chain was only as good as its weakest link. And these topics are entirely about glider CONTROL. And our fuckin' towing weak link, for all intents and purposes, only kicks in when a tow has gone totally tits up out of control. One or more of the pilots involved has allowed the tow to go out of control or put it out of control.
A weak link success virtually always puts the glider even more out of control but will USUALLY put things in a state in which control can be regained in a few seconds IF one has the luxury of a generous helping of air below him. If not, as is very commonly the case using a Hewett Infallible Weak Link, the flight is over and the glider WILL crash.
So anyone going up with any expectation that at some point he WILL be dependent upon his weak link has ZERO fuckin' business going up. Kinda like the way one doesn't fly into a rotor because one has a parachute which may open in time and stay open through the final twenty feet.
I once locked out on an early laminarST aerotowing. went past vertical and past 45 degrees to the line of pull-- and the load forces were increasing dramatically. The weaklink blew and the glider stalled--needed every bit of the 250 ft agl to speed up and pull out. I'm alive because I didn't use a stronger one.
Marc Fink - 2011/08/31 08:11:05 UTC
This all happened in a few seconds--in a lock out the line/bridle will likely be caught in your corner bracket further complicating things. I was actually in the process of reaching for the release and just about to pull it when the weaklink blew. If procedures were amended to "insist" on stronger weaklinks I would simply stop towing.
I have NOTHING but total CONTEMPT for the kind of total asshole who goes up with an easily reachable Reliable Release 'cause he's got an ultra safe 0.8 G Hewett Infallible Weak Link that will keep him from getting killed as long as he has 250 feet to spare. I would and do want the motherfucker fatally splattered to help get the sport cleaned up for the NON total douchebags.
We NEEDED Zack Marzec to get fatally splattered to end all discussions about Standard Aerotow Weak Links 'cause NOTHING ELSE was working and he was a very comfortable part of the problem. That perfect storm impact was the single best thing that ever happened in the sport - too little too late as it was though. And funny you were nowhere to be seen in any of the postmortem discussions. Ditto for fuckin' Peter Linknife Birren.
And if the "pilot" has been taught a bunch of crap about correcting for crosswinds by some incompetent moron and is upright with his hand on the control bars ready at the first sign of trouble to make the easy reach to his Reliable make-shift "Linknife" Release to cut his conspicuously unidentified Hewett Infallible Weak Link we have so many weak links floating around in this sewer that it's hardly worth talking about.
- If a glider hits the ground still on tow then the ground was the weak link in the system and his stupid Hewett Infallible Weak Link was as totally irrelevant as his stupid backup loop. If it's not a surface tow the tug - who hasn't fixed whatever was going on back there quite yet - may benefit from a designated weak link but we're just his passenger so his wellbeing is zero concern for us and responsibility of ours.
It may be the tow plane, the glider, the tow rope, or some other component of the complete system.
Save it. I'm sick of this crap already.
And you are certainly correct in realizing that you don't want either the plane or the glider to be the weak link in actual practice.
What a clever boy I am. But really... I owe so much to the top notch training I got from u$hPa certified AT professionals.
Therefore, one of the important purposes of a weak link is certainly for it to break before either of the aircrafts...
The plural of aircraft is aircraft.
...break. But it is not the sole purpose.
Then please to get in touch with Tost Flugzeuggerätebau and get them properly sorted out because they:
- have stated since the beginning of time that it is and most of the sailplane people are buying into this crap
- provide hang and para glider range inserts so they're obviously including us for that definition
In my opinion...
- What? Just in YOUR opinion? Not the undisputed opinion of a minimum of 97 percent of the world hang and para gliding towing community? Not a single other individual whose similar opinion you care to cite as being of like mind on this? After nearly 28 years of work in the sport as an official u$hPa darling? I can do a helluva lot better than that and 99.8 percent of the sport hates my fuckin' guts and will cut my wire before I'm able to get out an entire syllable.
- Fuck you and your goddam OPINION. This has been your goddam OPINION since the end of 1980. Wilbur and Orville didn't get us airborne on anything based upon their opinions. They did it all on theory and engineering. And now long beyond a century later every punctuation mark still holds up.
...the sole purpose of a weak link is "to allow the aircraft to recover safely when the weak link does break".
- The SOLE purpose. Structural overload protection doesn't even rate as a serendipitous byproduct.
- Even though you just said in your PREVIOUS SENTENCE...
Therefore, one of the important purposes of a weak link is certainly for it to break before either of the aircrafts break.
...there was another purpose of a weak link - the one and only one employed in conventional aviation. You needed a massive coordinated counterattack to properly discredit you and the lethal bullshit you spewed for decades.
- Oh. It ALLOWS the aircraft to recover safely when the weak link does break. Doesn't REQUIRE it to. So what if the aircraft doesn't feel like recovering safely? Don't we have untold thousands of examples of just that happening?
- RECOVER? Recover from WHAT? If the aircraft is recovering it's not flying - in a manner in which it can be controlled or at all. So what happens if/when the ground comes up before it can RECOVER?
- So there was nothing from which it NEEDED to RECOVER before the Infallible Weak Link kicked in, right?
- Don't you need a pilot to work with the aircraft and supply input required for recovery? If the pilot was so incompetent that he flew his glider into a potentially lethal situation on tow and lacked the competence to actuate his easily reachable Reliable Release how are we able to assume that he'll be able to safely manage his aircraft through a RECOVERY?
- What? No parachute? You don't seem to be able to recognize issues related to runway, ground, altitude so don't we have unlimited air in which to deploy a chute?
- How many videos do you have to show us how blindingly obviously validated your opinion is? I've got a whole shitload of videos and fatality reports to show pretty conclusively that it isn't.
Obviously, if the aircraft is the weak link...
The 75 pound seven thousand dollar six G certified weak link. I sure hope it doesn't get any stronger with continued use.
...recovery is impossible.
You've still got a parachute. Just float down and borrow another glider to give it another shot.
But even if the aircraft does not break, recovery may still be extremely dangerous.
So you've obviously decided to expand your "sole" hang glider definition of a weak link to conventional aviation 'cause there's absolutely nothing you're saying that's specific to hang gliders (it's finally occurred to me). And fuck them too if they're not in proper alignment with your opinion.
I've reviewed Donnell's four posts in this archive - all of them in the "Weaklinks" thread - and there's virtually NOTHING hang glider specific in them.
Lockout is THE hang glider specific towing issue. It essentially happens ONLY with hang gliders 'cause of our fundamental shit roll control authority relative to conventional gliders and the sport's willing embrace of the Hewett Easily Reachable Reliable Release Kool-Aid. If you're stupid enough to go up so configured - as 99 percent of the sport is - the classic lateral lockout is the ONLY situation in which you MIGHT want an Infallible Weak Link and you really want it bad and now. Nobody’s ever wanted an Infallible Weak Link for fear of being pulled forward at ten Gs but this is the issue Donnell keeps shoving down our throats while essentially totally dismissing lockouts - probably 'cause his Center Of Mass Bridle was supposed to have eliminated them by auto-correcting for roll and he doesn't want anybody thinking about that too much.
So, yeah, applying this:
In my opinion the sole purpose of a weak link is "to allow the aircraft to recover safely when the weak link does break".
pure total lunatic rot to ALL of towed aircraft aviation. Absolutely astounding. Delusional doesn't even begin to describe the pathology.
In the early days of towing hang gliders, the mantra was "Never use a weak link because it always breaks at the worst possible time...
- "...when the glider is climbing hard in a near stall situation." Yeah, that's what they do. You don't want them breaking at the BEST possible time - which is your strategy - 'cause then the best possible time instantly BECOMES the worst possible time. It's a lot like parachutes and ejection seats.
- But then you came along as the sole savior of the towed flavor of the sport - not to mention the rest of towed aviation - and solved all of our problems for us by making goddam sure there was something in the system that was gonna break and, for good measure, break every fourth tow whether anything was going wrong or not. And even today you remain this sole savior. How incredibly lucky we all are. ('Cept in conventional glider towing in which you've had total zero impact.)
...and when it does break it only increases the danger of the situation."
Count on it - if you're low. But if it didn't break you were gonna die in another second or two ANYWAY. So you can't afford to get into a weak link situation unless you've got tons of altitude for stall recovery or parachute deployment.
They tried to beaf...
Take the "a" in "beaf" and swap it with the second "e" in "weeklinks" back up in your first sentence. (Can you really get away with spelling "beef" like that in Texas?)
...everything up so that nothing would break.
Gliders, bridles, releases, towlines, winches, mountings... What WERE they THINKING!!! And the legacy of a lot of this crap remains with us to this very day!
But something would always break when the towing forces became strong enough. And when that something broke (even if it was not the glider), someone would die.
- And every single one of the assholes who beafed everything up so that nothing would break eventually was killed. Not one single survivor anywhere. And you can make this statement because you're all knowing and all seeing.
- EVEN if it was not the glider? Implying that way more frequently than not it WAS the glider. Yeah, they DID break up a fair number of early gliders in early towing. But the problem wasn't three G tow systems. The problem was two and a half G gliders. That got fixed. Somebody find me one single example of a properly preflighted HGMA certified glider breaking up under positive loading save for badly blown aerobatics.
Can we even imagine what it would take in terms of tow power and transmission to break up a glider? Ya know what a glider looks like when it's strapped to he truck to pass certification for positive loading? Versus:
Zack hit the lift a few seconds after I did. He was high and to the right of the tug and was out of my mirror when the weak ling broke. The load on the tug was not excessive as with a lockout, but I was not surprised when the weak link broke. I was still in the thermal when I caught sight of Zack again. I did not see the entry to the tumble, but I did see two revolutions of a forward tumble before kicking the tug around to land. The thermal was still active in the area that I had just launched from so I did a go round and landed on a runway 90 degrees cross to the direction we were towing in.
This is total fucking rubbish. Yeah, in the dinosaur days there was junk that would fold up in normal free flight situations. We're not the least bit concerned with that 'cause HGMA certification totally dealt with it just after the dawn of time. That's six Gs and no glider has ever been towed at over two. The winches and boats weren't capable of doing it, the truck drivers weren't total morons, and the tugs aren't capable of it and didn't exist until after a fair bit into the Eighties.
And ya wanna know EXACTLY what was killing gliders in the pre certification, pilot connection, Infallible Weak Link days?
Manned Kiting
The Basic Handbook of Tow Launched Hang Gliding
Daniel F. Poynter
1974
"A bad flyer won't hurt a pin man but a bad pin man can kill a flyer." - Bill Bennett
"Never take your hands off the bar." - Tom Peghiny
"The greatest dangers are a rope break or a premature release." - Richard Johnson
Exactly the same shit that's always killed gliders. You can't cite me a single incident report to document this fiction you're spewing. And not one other participant in any of these discussions has ever stepped forward with anything either.
And check this out from these assholes:
Dr. Trisa Tilletti - 2012/06
You and I have flown sailplanes for almost as long as we have flown hang gliders. We own two sailplanes and have two airplanes that we use for towing full-size sailplanes. In all the time that we have flown and towed sailplanes, we have not experienced or even seen a sailplane weak link break.
So for every single flight they're talking about the weak link could've been fifty Gs and it wouldn't have mattered in the least. Just like it would've never mattered for any of the flights of my entire career if my parachute had been secured to my carabiner with a loop of a piece of worn-out shoelace.
And that son of bitch is on this wire letting you get away with this outrageous moronic crap. And he's gonna cite you in his bullshit article as a respected authority. He's gonna reference the crap from my conversation with you in this thread from your 2008/11/05 21:23:39 UTC post. And he's gonna spell your name wrong. (Birds of a feather.)
- And you were the world's foremost authority on tow crashes and what was causing them. When the Brooks Bridle came out in early 1982 you couldn't be bothered to look into it to the slightest degree - see how its performance stacked up against your Skyting Bridle, if either system featured aspects which could be beneficially incorporated in the other, why your bridle wasn't performing as you predicted it would. Ditto for when two point aerotowing emerged on the scene. And we're supposed to recognize you as an established authority.
Imagine a 4 g towline pulling forward on a the center-of-mass of a pilot-glider system shortly after take-off.
Imagine a Jeep falling out of a military transport plane and onto you and your glider as you're commencing the tow. The difference... The latter scenario's the more likely one.
It's totally fuckin' RIDICULOUS to talk about a glider of any description towing at four Gs under any circumstances. We tend to tow aero at under a half G and we may get turbulence related spikes up to one or a bit over. If you're towing fixed line surface you shouldn't be and even if you are there will be line sag which will dampen spikes. And for payout the goddam weak link is pretty much totally irrelevant.
This would pitch the nose of the glider upward at some 80 degree angle above normal flight (arctan 4).
Obviously must be on a 4 G towline. (Funny the outboard leading edge spars don't seem to be bowing up all that much.)
If you're pitched up at some 80 degree angle above normal flight you're beyond vertical and moving back away from what's pulling you. It's impossible for that to happen.
Here's maybe the best example ever of anything along those lines ever recorded on video:
That's on a payout winch so the tension isn't all that ridiculous. At the end of the tow he's going straight fucking up and it's not requiring him three or four Gs to achieve that attitude. And he's fine until his "weak link" - which was his bridle in this particular case - increases the safety of the towing operation and comes close to putting him in a fatal Zack Marzec flavor tumble.
Zack Marzec himself we'll throw out 'cause aerotowing minus a keel attachment is lunatic fringe activity but he was able to pull off the fatal tumble with no more than a 0.8 G pull.
Nah, let's not throw him out. You're gonna say, later in this post:
But I still believe, "Anything that can go wrong will go wrong." It is only a matter of time.
So it doesn't really matter that these Flight Park Mafia fuckin' assholes DELIBERATELY eliminated the trim attachment for the glider. It would've happened anyway with everyone trying to do everything right. It would've just been a matter of time. (And we never heard the slightest peep out of you condemning this global lethal bullshit practice in no uncertain terms - even after Dennis Pagen reported almost getting his stupid ass nearly killed in exactly that way in the 2005/01 magazine issue.)
Actually, now that I think of it, when Zack was topping out, he WAS flying Center Of Mass - due to the platform tow equivalent tow angle. But it was a bit late for that to have been doing him much good.
If the towline or weak link...
Two words here - for a pleasant change.
...broke under those conditions, the glider would whip-stall at that low altitude and plumet into the ground.
- And if the towline or weak link DIDN'T break under those conditions, the glider would continue climbing. And if the pilot were acrophobic he might die of a heart attack.
- If the towline breaks the weak link isn't the weak link and the flight had no fuckin' business leaving the ground.
And if the towing were not CM...
- See Zack Marzec above.
- A one point surface tow at a significant tow angle is Center Of Mass. Actually, now that I think of it, when Zack was topping out, he WAS flying Center Of Mass - due to the platform tow equivalent tow angle. But it was a bit late for that to have been doing him much good.
- If by not "Center Of Mass" you mean connections at the top and bottom of the control frame (nothing on the pilot) it doesn't matter all that fuckin' much as long as the glider's pointed at whatever’s pulling it. I know this 'cause I've done it.
...or if the glider were in a lockout, the situation would probably be even worse.
- If the glider's in a lockout it's not really a tow anymore. We don't need to be talking about it. If I'm going sideways I'm gonna blow my Rube Goldberg release to end the situation but you're more than welcome to wait around until your Infallible Weak Link does your job for you.
- The glider can be in a lockout while going straight up. The definition of a lockout is a situation in which the tow force overwhelms the pilot's control authority. Here's the classic surface tow example:
At that tow angle the configuration is as "Center Of Mass" as it's possible to get. And NOBODY wants an Infallible Weak Link of any rating or description permitting that flight to recover from its tow phase.
Twenty-three posts. And NOT ONE suggestion that the "pilot" should've safely terminated the tow as things began getting ugly with his Reliable Release. And that's EXACTLY the same as screaming that you don't want your fucking Infallible Weak Link to kick in and allow the aircraft to "recover" safely.
And we'll note that you don't recognize that situation as a lockout.
Donnell correctly states that:
The appropriate strength of a weaklink does not depend upon weather conditions or the flight attitude of the glider (turbulence, wind gradient, lockouts, etc.). It is impossible to design a weaklink to release the pilot when he looses flight control because there is no correlation between towline tension and flight control. (A pilot may be in perfect control under high tension but out of control under low tension.)
but immediately goes on to say:
A weak link can only be designed to release the glider under the worst possible conditions before the towing forces exceed the limits of safe recovery when the weaklink breaks.
Am I the only one who sees those two snippets as mutually exclusive?
I am sorry you find those two statements mutually exclusive. The key word in the first paragraph is "flight" and the key word in the second is "recovery." A pilot may well be able to control the glider in flight with a 10 g towing force.
No he won't. His glider will have become scrap metal by no later than six Gs rope plus the one G you have without the rope.
But very few pilots could control the glider immediately after that 10 g towing force suddenly became a 0.
- Got news for ya, Donnell... ZERO pilots can control a glider in any "RECOVERY" 'cause the thing one's RECOVERING is CONTROL. He's stuffing the bar and maybe getting over to a side to RECOVER as quickly and efficiently as possible but for the time being he doesn't have an aircraft to control. He's a falling object strapped to another falling object which will eventually revert to being an aircraft again IF:
- it doesn't tumble; AND
- the ground doesn't come up first.
And there's no weak link capable of getting the shit airborne light enough to protect against stalls, tumbles, impacts 'cause stalls, tumbles, impacts can and do occur with gliders that have never been on tow once in their entire lives.
- See above. You use these totally ridiculous scenarios that have never happened and can't possibly happen in real life instead of looking at and talking about the more extreme real world stuff for which we have tons of solid data.
It would take an expert aerobatic pilot both time and altitude to get the glider back under control.
Bull fucking shit. Adam Parer WAS (past tense) an expert aerobatic pilot who failed to clear his airspace before diving to commence a loop. He had to pull up abruptly to avoid a collision and that doomed him to a fatal tumble. He became a total passenger a second and a half before his airspeed dropped to zero. And a half decent Day One student will fully stuff the bar in response to a severe stall one hundred percent as quickly and effectively as an expert aerobatic pilot and won't end up any more tumbled and dead than an Adam Parer will when that's not enough.
Same deal with expert and highly experienced tow pilots. There's only so much one can do and a twenty year Hang Five won't be able to do it any better or faster than a solid two day Hang Two.
But most non-aerobatic pilots would find it almost impossible to recover from a whip-stall safely, especially if it occurred near the ground.
Whereas just about all of your half decent aerobatic pilots can safely recover from whipstalls near the ground in their sleep. What planet is this guy from? Who the hell signed him off on a Two? Is it the slightest wonder that he taught Lemmy how to correct for crosswinds?
For many years I subjected myself to the tyranny of the conventional "wisdom" that the only acceptable weak link for a solo glider of any weight is a single loop of 130 pound Greenspot at the end of a bridle.
I hook up at about 320 pounds and with that junk at the top end of my two point bridle I get AT BEST 0.76 Gs. (At worst I get 0.39 Gs but let's ignore that for the moment.)
I'm glad you finally learned that one size does not fit all and that the number of g's is the correct unit of measure.
- Chad told me at the beginning of the Ridgely operation that a single loop of 130 pound Greenspot installed on a bridle with the knot hidden was 260 pounds. I very stupidly trusted and believed him. But the same crap was published on Quest's website, it was being perpetrated globally for hundreds of thousands of tows, and I notice you never breathed a word of dissent in all that time - or came out and backed me up as I began going to war.
- The number of Gs ISN'T actually the issue. It's solely a function of the glider's max certified operating weight.
- Since smaller gliders are built using the same tubing, wires, sailcloth that the larger ones are the little ones are proportionally way stronger than the big ones. Thus we pretty much CAN do one-size-fits-all. And I can almost live with four hundred pounds towline and something stronger up front.
The last time I remember being locked out (three years ago - at altitude) I was on my ear - thirty degrees beyond the placarded roll limit of my glider - before my brain finished connecting to my hand. And the little string was still doing just fine.
Karen hooks up at 200 pounds and - of course - uses that same weak link (which she's never broken) so she's limited to a max of 1.22 Gs. I'm thinking she could win an aerobatics competition without ever hitting her release.
Practically speaking, I don't believe that - given enough air - there has ever been an incident of any pilot of any skill level having a problem recovering from any attitude achievable while connected to a tug through a weak link of any strength.
And then on 2013/02/02 we got the Zack Marzec perfect storm.
I am glad to hear this. Perhaps your experience has been with reasonably well tested towing operations that try to minimize the chances of any kind of danger.
- My experience was entirely with stupid, incompetent, arrogant, sleazy shits who pissed all over everything I did to get the sport on any kind of sane track. And you were the primary asshole who enabled them.
- The only way to minimize the chances of any kind of danger is to only tow in sled conditions. That's obviously been working out great for you for decades but for the vast majority of people I know the object is to maximize the chances of any kind of danger by going out in prime soaring conditions but get the fuckin' tow over with as quickly as possible. 'Specially the first couple hundred kill zone feet. And by far the biggest obstacle to doing that is your fucking Infallible Weak Link.
- Name some poorly tested towing operations that DON'T try to minimize the chances of any kind of danger. And tell me why they're operating under u$hPa certifications and SOPs.
Furthermore, one of the characteristics of aerotowing is that it regulates towline tension by matching the speed of the tug with that of the glider.
As opposed to what? You've got two planes tied together by a 250 foot spectra rope. What other options do you have?
In the early days before the Dragonfly this was a problem because the stall speed of the typical tug was near or above the maximum speed of the glider.
Rubbish. The maximum speed of the glider is well over fifty miles per hour. The trikes were fast but the big problem was that the morons were hooking us all up one point 'cause even the shoddiest two point release was beyond their depths.
In those days, if the glider pilot did anything except stuff the control bar, the single-surface glider would shoot upward and sometimes drive the tug downward.
I got damn near straight over John Leak's Cosmos and didn't drive it downwards. This is a totally manufactured risk to the tug. You cite me ONE ACTUAL EXAMPLE of a tug being driven down by a high glider. It's a totally manufactured threat.
Tugs are ALWAYS climbing. If a situation ever got so far south that the tug could no longer climb and the weak links were still holding one of the two humans involved would have already hit a release.
I guess things have improved.
Well I guess if you're operating the most highly evolved and finely tweaked tow operation humanly possible that it certainly wouldn't be worth any of your valuable time to look at the way these hundreds of thousands of tows are going off, find out what is and isn't crashing gliders and tugs, see how well Skyting Theory is predicting what's actually happening.
But I still believe, "Anything that can go wrong will go wrong."
- Would a glider just off the runway being hit by a thermal such that it climbs hard into a near stall situation, having the ultra safe 0.8 G Infallible Weak Link increase the safety of the towing operation at the worst possible time, inconvenience stalling and crashing with devastating consequences for the pilot and glider count as something going wrong? Or do we just write thirty of those off as pilot error / crappy towing skills and talk about how great the ultra safe 0.8 G Infallible Weak Link worked to keep douchebags like Peter and Davis from getting dragged after stupid blown dolly launches?
- Anything that CAN go wrong already HAS gone wrong - multiple times. I don't lose the least amount of sleep over them for the same reason I don't worry that I'll have a sidewire failure. I know how to preflight my glider such that if I have a sidewire failure it'll happen in the setup area.
- I got news for ya, motherfucker. The solution to everything that can go wrong on a tow isn't a 0.8 G Infallible Weak Link. 99.9 percent of the time the 0.8 G Infallible Weak Link is the thing that's going very seriously wrong. The scale is absolutely astronomical.
- Anything that CAN go wrong WILL go wrong ONLY if the assholes running and participating in the operation ALLOW it to. You name me one thing that can go wrong that can't be safely prevented, neutralized, responded to, compensated for by halfway competent crew, drivers, observers, pilots. Anybody who believes otherwise has no fuckin' business flying. And anybody who believes that so much as one single problem can be safely addressed by an Infallible Weak Link REALLY has no fuckin' business flying - let alone advising anyone else how to do it.
It is only a matter of time.
Well then, since nothing relevant has ever gone wrong with a tow conducted in adherence to the Twelve Points of Skyting Theory I guess we can safely conclude that there's absolutely nothing wrong with it. Congratulations on having totally nailed it without even having included stuff like dolly launches and Rube Goldberg release systems which allow the pilot to blow tow prone with both hands on the control bars connecting tube at all times.
For the purpose of this discussion we're only hurting and killing AT people who are too low to be able to recover and weak links have never been issues in these scenarios.
If a weak link is too weak, it could contribute to this problem by increasing the number of un-intended releases at low altitude.
That's not a safety issue. Unintended releases at low altitude are mere inconveniences and any crashes experienced are sole consequences of incompetent douchebags who haven't bothered to perfect their flare timing. Please do try to keep this discussion properly on topic.
I hope we can all agree that there's no way freakin' way that those situations can be safely and reliably defused by weak links. Those problems have to be mitigated by the development of flying judgment and skill, use of reliable...
Crap. I said "reliable".
...and easily actuated releases at both ends of the tow line, liberal use of wind streamers, and correlation of conditions to skill level.
Yes, I agree.
So I don't agree that it is appropriate to scale weak link rating to pilot skill level. This seems to carry the false assumption that the weaker the link the safer the flight and - trust me - there are plenty of situations in which the last place you want to find yourself is off tow. I can think of at least two people who were killed because they really needed line tension and couldn't get it and one who is alive and well because he did.
In most forms of towing, a weak link that is too weak is more of a nuisence...
- There's only one "e" in "nuisance", Donnall.
- "Inconvenience" is the proper Industry Standard term. Do please make an effort to stay current with the state of the technology.
...than a danger. As long as the break occurs while a clear landing area is below, the pilot simply flies down and lands.
- After the recovery of course. But that goes without saying.
- Well duh. It's not like there'd ever be a stall involved subsequent to an Infallible Weak Link success that anyone would need to deal with prior to his perfectly timed landing flare.
- And never once in the entire world history of hang gliding has anyone ever had the slightest problem simply flying down and landing in a clear landing area. There can be no circumstances or conditions in which a pilot who got demolished on suitable terrain would've been OK if he'd continued climbing out on tow.
However, aerotowing has its own unique characteristics that may well alter the situation. Dolly take-offs...
DOLLY takeoffs? Why would anyone in his right mind add the complexity of a dolly launch to an otherwise simple, solid, proven system that works?
...speed-regulated tension, critical flight position of the glider relative to the tug...
...accommodate fairly major conventional fixed wing stuff. Just how far up one's ass does one need to have one's head inserted to be that totally clueless about the highest volume hang glider towing operations the world will ever see? We're blowing idiot Standard Aerotow Weak Links every other tow and Donnell thinks the vast majority of those gliders are ending up in the trees. Reminds me a lot of:
We always told towed pilots that the first 500 feet belonged to the tug pilot. They have enough to do to keep themselves safe.
Jim Rooney - 2008/12/11 18:45:01 UTC
Yup, the first 500ft are mine. Try to keep up. Your tugger generally REALLY wants to help you, and will do all that he can to do so, but he's got trees to stay out of as well.
I guess when one is bending over backwards enough to not acknowledge that there can be negative consequences to abruptly losing three hundred pounds of thrust shortly after takeoff it's not that much extra effort to insert one's head a fair bit up one's ass.
...are all unique to aerotowing.
Sure Donnell, whatever the world's foremost authority on hang glider towing says.
Therefore, an aerotow weak link needs to be strong enough to stand up under normal take-off and flight operations.
And let's keep studiously ignoring the ABnormal takeoff and flight operations in which Mother Nature insists on deviating from any of the Twelve Points of the Skyting Criteria.
Nevertheless, you yourself mentioned that a weak link strong enough for one pilot to fly comfortably could well put another pilot in aerobatic flight.
I myself also mention that the one pilot with the weak link strong enough for one pilot to fly comfortably can and will be the same pilot who can be put into aerobatic flight by the same weak link. In fact I've been that one pilot on that same idiot one-size-fits-all Standard Aerotow Weak Link on those two occasions.
Let's further note that I was flying properly trimmed two point with a Standard Aerotow Weak Link slightly off the bottom end of the legal range, got rolled starboard beyond placard, released with my Standard Aerotow Weak Link holding just fine, RECOVERED thirty feet below onset altitude. Onset altitude was 2332 feet AGL. How would my recovery have gone if onset had been twenty feet AGL? And what weak link rating would you advise for that particular situation?
So, again, one size does not fit all.
Idiot.
There is another characteristic that distinguishes aerotowing from other forms of towing.
That there's a fuckin' idiot ultralight pilot on the front end whose plane, gas, and time you pay for who appoints himself Pilot In Command of YOUR aircraft and dictates what you are and aren't allowed to configure your plane with to maximize your safety and efficiency.
Any pilot that is awarded...
...or sold...
...an AT rating or allowed to solo must have demonstrated the ability to control the glider under normal tow operations.
And safely respond to a Standard Aerotow Weak Link success simulation under low tension at smooth air at high altitude when his tandem instructor determines things are optimized enough to safely proceed.
This includes the skill to keep the glider properly positioned behind the tug in typical thermal conditions.
- Define typical thermal conditions. On the afternoon of 2013/02/02 Mark Frutiger pulled up a solo tandem aerotow instructor on state-of-the-art equipment in what had been all day prior and was assumed would remain total crap thermal conditions. Shortly after the planes got airborne there was an abrupt eruption of astonishingly excellent thermal conditions and while the tug pilot wasn't the least bit fazed the tandem aerotow instructor ended up DOA. And to this day no one has the slightest clue as to what went wrong - in spite of the ultra safe Standard Aerotow Weak Link having worked perfectly and in full accordance with our expectations (as defined in Dr. Trisa Tilletti's fourteen page magazine article eight months prior).
- You show me an AT rating requirement from any point in the history of u$hPa for keeping the glider properly positioned behind the tug in typical - or ANY - thermal conditions. u$hPa avoids discussing situations in anything but glassy smooth air 'cause none of the bullshit they teach, mandate, sell WORKS in anything but glassy smooth air. Try reading the excellent book, Towing Aloft, by Dennis Pagen and Bill Bryden and finding any scenario from the REAL world that can't be safely controlled, dealt with, survived by Joe Hang Two with an easily reachable bent pin reliable pro toad release, Standard Aerotow Weak Link, hook knife, and tug pilot constantly poised to make a good decision in the interest of your safety. Then watch what happens with and to both of those stupid lying dickheads when they're out in the REAL world.
- There is no SKILL that can be used to keep the glider properly positioned behind the tug in typical thermal conditions because typical thermal conditions can and do overwhelm the crap outta our control authority. In typical thermal conditions there's a two hundred foot kill zone that's gotta be survived before one can start to breathe easy. And you've gotta have top notch bulletproof equipment - including a launch cart, weak links at BOTH ends that will and can not under any circumstances inside of that kill zone increase the safety of the towing operation - to do it. Typically you need to stay on tow as long as it's controllable and be able to blow off with both hands on the CONTROL bar the millisecond you're able to determine that the tow won't be sustainable. And even then there are no guarantees but the historical record shows that the risk is negligible to zilch.
Such a skill level is considerably greater than that of rank beginners learning to hang glide by towing.
1. Must be a current USHPA member. Foreign pilots must obtain a 30-day temporary USHPA membership.
2. Must have a pilot proficiency rating of H3 with Aerotow (AT) special skill rating or foreign equivalent (IPPI card). H2 for Sport Class with permission from the meet organizers.
3. Must have aerotowed with the glider that he/she is flying or similar at least ten times. Practice tows will be available onsite on Saturday before the first competition day.
4. Pilots under the age of 18 must have a parent (or guardian) written consent (notarized) to participate in the competition.
If u$hPa says that a Hang Two little kid with zero towing experience of any flavor can hop on a cart solo in light morning conditions, repeat nine times, then compete in world class thermal conditions pro toad with a Tad-O-Link with no restrictions then just how much considerably greater skill level can possibly be involved? And when we see launches like:
14-0614 - 18-0801
and:
27-0721
from the meet head and regular comp pilots?
Clearly, beginners just learning to tow do not have the ability to recover from a 1.5 g weak link break.
Clearly they fucking well DO when things are otherwise going reasonably right and NOBODY does when things are less ideal than they are in a Quest Mitch Shipley ground school scenario. There's no skill involved in stuffing a bar and waiting for a glider to start flying again - or splattering back onto the runway depending on initial inconvenience altitude.
And please explain to me why all sailplane manufacturers specify 1.4 Gs and have never since the beginning of time breathed a single whisper of bullshit about relevant pilot skill and experience?
They should be flying with a towline tension around 0.5 g and have a weak link that breaks somewhere around .75 g...
Pity that's clearly illegal under current (2004/09) AT regs. Fuckin' gov'nmint. Tellin' us what we can and can't do, curtailing our God given freedoms, needlessly endangering our lives just for the fun of it. Let's march on Washington and start Making America Great Again.
...surely no greater than 1 g.
Perish the thought. That's WAY more than half sailplane specified and current u$hPa recommendation (regardless of rating, skill, experience level).
On the other hand, any rated tow pilot should have the skills and ability to recover from a 1.5 g weak link break (or even a 2 g break).
- And yet that leaves one wondering why guys like Bill Bennett, Jamie Alexander, Frank Spears, Mike Del Signore, Rob Richardson, Mike Haas, Arlan Birkett, Zack Marzec as dead as they got.
- How is Any Rated Tow Pilot supposed to develop these skills and abilities to recover from 1.5 g weak link break (or even 2.0) G weak link breaks? The one simulation which fully qualifies him is at 0.4 and under super ideal conditions. They force everyone and his dog to fly 0.8 if you're not a lucky little girl. The tug's three strand tow mast breakaway protector limits max possible tension to 330 pounds and leaves you with the rope. So exactly where are you supposed to be getting all this practice and experience? Is anyone beefing up the front end crap enough to be able to offer tandem Tad-O-Link recovery clinics for two hundred bucks a ride in the morning and evening smooth air windows?
So in the case of aerotowing, I tend to agree with your above statement.
Please tend to agree with my statements as little is possible. I hate to say it but this is a bit like having Ryan Instant-Hands-Free-Release Voight and Jim Keen-Intellect Rooney saying favorable things about one.
However, in general I still believe that the weak link break strength should be adjusted to pilot skill for hang-1 and hang-2 pilots.
We don't tow Ones on anything but low scooter. We need to have people solid on roll control before we start getting them high enough to be able to kill themselves. And of course they also need to be trained on how to correct for crosswinds.
The way things are almost universally practiced now is... The smaller you are - the higher G rating you get. Brilliant.
And it gets even worse 'cause the bigger you are the faster you degrade a marginal weak link. Therefore Karen may start out with a 1.22 G weak link and end up with the same at half a mile up. That same weak link - 0.76 Gs for me when I put it on the bridle - starts breaking fibers as soon as the tug starts moving and can fail before I get to a hundred feet.
This is one of the main reasons I use the Linknife as my primary release. I have never had it fail to cut the weak link and release me from flight when activated. Therefore, every flight utilizes a fresh, new weak link.
- I WAS TALKING ABOUT a fresh, new, hideously understrength weak link. They degrade DURING the tow - commonly to the point of success.
- And you COULDN'T POSSIBLY just use a vastly superior release system that DIDN'T cut the fresh high precision fishing line every tow and just replace it for each launch.
- If you've never had the Linknife fail to cut the weak link and release you from flight then why are you using it as you PRIMARY release? Do you not trust it? After you've made the easy reach to blow it in an emergency situation will you still have time, altitude, control enough to blow you backup release?
- Who the fuck cares whether or not YOU've never had it fail to cut the weak link and release you from flight when activated? Anyone with half a brain or better will look for incidents in which it HAS failed to cut the weak link. And we've had them with the Linknife - not that you'll find anything of an advisory at Peter's bullshit website. What you WILL find is:
Your tow release MUST work every single time.
implying that it DOES.
- It's been disabled by wheat stubble - and that could happen low on tow in a dust devil. And as it happened on the ground it DIDN'T need to work. But in a low level dust devil one COULD easily be in a situation in which it really NEEDED to work.
- Also Peter doesn't consider inability to blow his stinks-on-ice configuration in an actual critical situation in which he needs TWO hands on the CONTROL bar as any kind of failure. And he's been fairly serious injured in one incident and damn near killed in another as a consequence of his having to make an easy reach. Those are the only two incidents he's reported so based on those statistics we should rate it for zero percent reliability in any actual emergency situation.
- But I guess none of that really matters 'cause you're using an Infallible Weak Link to guarantee a safe recovery no matter what. (How strange that things ended for Lemmy the way they did.)
And every pilot can use the weak link that he or she finds comfortable flying with.
Yeah, sure he or she can. The passenger he or she is towing however... Not so much.
The FAA - with respect to sailplane towing - specifies a 0.8 to 2.0 G weak link range. I presume they do this to define limits for safety. Three observations:
- They don't correlate anything inside this range to pilot skill level.
- It appears that they consider anything under 0.8 Gs to be dangerous. So do I.
- If these are indeed reasonable lower and upper safety limits and G rating has no correlation to pilot skill then the safest number - the one or which EVERYBODY should be shooting - is the one in the middle - 1.4 Gs.
Again, everyone piloting a sailplane solo and everyone rated to pilot a hang glider solo has similar skills. Certainly they have mastered the minimum safe skills to pilot the gliders under typical conditions. Therefore, a weak link that breaks anywhere in the 0.8 to 2 g range should be appropriate. Somewhere in the middle (about 1.4 g) may even be more appropriate. However, I see no good reason for everyone to shoot for the exactly that same value. Anyone skilled enough to recover from a 2 g break can recover from a 0.8 g break.
- Well duh. Recovering from an 0.8 G break is two and a half times as easy as recovering from a 2.0 G break. Just do the grade school level arithmetic if you don't believe me.
- "RECOVERING"??? I thought the weak link success was the recovery from the dangerous tow situation. Why do we need to be recovering from a recovery? If we get tumbled by severe turbulence and hafta hit the silk do we need to recover from the full successful deployment?
- What if the ground should happen to come up during our recovery process? What procedures should we be practicing for such an eventuality?
They do not need to limit themselves to 1.4 g. However, when they get above 2 g's they are...
...operating illegally and no one wants to do it anyway so why are we burning up perfectly good bandwidth discussing it?
...beginning to push the envelope of safety.
Yeah, really bad things can start happening after 2.0. The glider can stall. And then ya gotta wait until that's done with before you can start initiating your recovery procedures. I shudder to even think about it.
And the farther they get below 0.8 g's they more they are asking for unexpected pre-mature releases over potentially dangerous terrain.
ALL terrain is potentially dangerous in this aviation game. That's why you wanna have your shit and plane totally together whenever you're operating near it, limit your time in close proximity to it to a bare minimum, and avoid discussions with people who have opinions on relevant issues.
Also, I'm not buying that because the normal tension involved in forward is less than that involved in downward pulling towing that you scale the weak links accordingly. If anything - correct me if I'm wrong - it should be = the opposite.
Increasing the tension pulling forward increases the glider's air speed until the nose can no longer be kept down. (The effect of a 1-g forward tension is the same as if the glider were being flown in free-flight at a downward angle of 45 degrees. A 2-g forward tow tension is equivalent to a 60 degree dive. No hang glider can maintain such dive angles for very long. Their increasing air speed will soon force them to start pulling up out of the dive.)
- Bullshit. By your own explanations when your being pulled forward the effect is exactly the same as gravity increasing in strength and shifting forward. You and your glider are getting heavier while trimming higher nose-up with the bar in normal trim position. When you're diving in free flight you're shifting the glider/pilot system's CG forward. You're speeding up, the bar's back, and you're not getting heavier.
- A glider can maintain a dive as long as it has air below it and it's pilot can hold the bar stuffed.
- We're NOT TALKING ABOUT increasing the tension pulling forward and increasing the glider's airspeed - you moron. We're talking about increasing the range of tensions through which the glider pilot can ELECT to remain connected to the thing that's supplying his thrust and pulling him up and away from the unsuitable terrain.
- I got news for ya, Donnell... Eliminating all dedicated weak links in the system and using the two thousand pound Spectra towline as your weak link doesn't necessarily mean that you'll be towing with an instantaneous and steady two thousand pounds of thrust from just after the launch signal through release at 2500 feet five seconds later. See if you can get a firm grasp on that concept. It'll save us a lot of time and frustration.
When the nose comes up the forward speed of the glider will decrease and the position of the glider will become dangerously high possibly forcing the tug down.
Fuck yeah. With even just 650 pounds of thrust being lit off by a 2 G Tad-O-Link the tug will be on the runway on its nose ten or fifteen yards upwind from start position. Good thing those Dragonflies use pusher props. Bobby Fucking-Genius Bailey obviously thought totally through the scenario of a glider with a Tad-O-Link overriding his tow mast breakaway protector.
Unless the tug also slows down...
I got more news for ya... The glider ALWAYS slows down the tug. If you don't believe me get on a Dragonfly, pull a glider up fifty feet, squeeze the release lever to increase the safety of the towing operation, see what happens with the Dragonfly while the glider's recovering from the nuisance.
...the difference in air speed will increase the tension even more as the situation worsens the difference in air speed...
And the less ideally the glider's positioned and trimmed the more it slows the tug down. You're never gonna have a situation in which the glider's airspeed is 35 and the tug's is 40. The converse... Yeah. Think kid running into the wind with kite string and stunt kite.
...will increase the tension even more as the situation worsens until either the weak link breaks or one of the pilots release.
One of the PILOTS releasing? What's that? Releasing in any emergency is the job of the weak link. What other reason would one possibly have for flying with one?
Then the issue becomes that of how to recover safely.
No-brainer. Just make sure you're nice and high. The number of incidents in which that solution doesn't leave you and your glider smelling like a rose is too microscopic to bother with.
A weak weak-link prevents this situation from becoming as extreme as a strong weak-link allows.
And since our Releases are merely Reliable while our Weak Links are Infallible we'll obviously need to Rely on our Infallible Weak Link rather than function as Pilots.
In aerotowing you're not much worried about excess forward pulling tension 'cause that "problem" is gonna take care of itself pretty fast by translating to speed and altitude. The situation in which it's gonna be desirable to lose tension real quick is when the glider has rolled so far away from the tug that it ain't coming back and that is not a forward pulling scenario.
Aerotowing should never be a "downward" pull.
You're quite correct on this. It SHOULDN'T so we'll just ignore the scenarios in which it IS.
So the weak link break point should ALWAYS be designed for that of forward pull.
Obviously. When everything is lined up perfectly and you're climbing out fast and fine is THE situation in which you most want your weak link to increase the safety of the towing operation. Then you can go back up and properly correct for crosswinds.
You should NEVER use a stronger down-pull weak link (say 3 g's)...
Talked me right out of it. Well done. Now I'll have a lot less trouble dealing with the tug drivers and the FAA.
...while aerotowing for pricely...
Not a word, Donnell. Try adding a syllable.
...the reason you mentioned above. As soon as the aerotowing situation becomes a down-pull, the weaker forward-pull link needs to break.
Since the eagles will have obviously finished eating off all four of out hands by this point.
And since aerotowing is speed controlled the tension starts going up fast when you start getting out of kilter. And - trust me - you don't want to be popping off tow every time you have to plow through a little turbulence.
Conversely, since most downward pulling towing is tension controlled, you can generally get away with a lower rated weak link 'cause normally it's impossible to get much of a deviation no matter what you do..
It is only the forward component of any tow force that makes the glider climb. The downward component only adds to the effective weight on the glider. Therefore, if one is towing with a towline at an angle of 60 degrees down (i.e. the glider is toping out above the ground tow vehicle), a towline tension of 1 g will only produce 0.5 g of forward thrust - enought to maintain flight even with the added weight, but not enough to climb appreciable. Unlike aerotowing which has unlimited sky in which to climb...
...but notoriously limited terrain in which to accommodate nuisance landings...
...ground towing usually has a limited space. Therefore, the only way to increase the release altitude is to climb with a forward thrust approaching 1 g. This means the towline needs to have 2 g's of tension at a 60 degree towline angle and 3 g's at 70 degrees. Such tensions pulling forward could be desasterous if the weak link breaks.
Yeah Donnell, I imagine going to three G's thrust on a forward pulling tow with a three G weak link COULD be pretty "desasterous" (spelled wrong two different ways). Here's a couple thoughts...
- Use a four G weak link to pull forward at three Gs.
- Just pull forward two and a half Gs with your three G weak link.
No wait. You're required to pull at whatever weak link rating you're using. It's like when your car has a speedometer that goes up to 120 that's the speed that you gotta maintain at all times when you're driving to the grocery store. I got nuthin'.
But such a break at 60 or 70 degrees simply lightens the load on the glider and presents only a minor control problem. Therefore, down-towig may need and can safely use a weak link of 3 g's or more...
'Cause nothing bad can ever happen on a surface tow with a tension of three Gs or under.
He must've overloaded his brain's physics circuitry and pulled all the current out of the spelling sectors.
And if the FAA has anything to say with respect to weak link safety ranges being different for aero and winch towing - I can't find it.
I doubt if the FAA makes such a distinction.
The FAA doesn't give a flying fuck what we do with surface - or really anything else other than airspace in the way of violations. Splatter a little kid on a shitrigged fake instructional tandem surface tow... Sorry, not our department. Best wishes on your future endeavors, general public.
If I am not mistaken, most sail planes are towed from the nose of the glider.
- This is late 2008 and there are fairly easy ways of finding out whether or not one is mistaken before posting.
- Sailplanes is one word. If you can't even spell them right maybe you shouldn't be discussing them.
- As opposed to the nose of the kayak?
- Maybe we should be looking at some of the least sailplanes for the purpose of this discussion.
Therefore, aerotowing is forward towing.
Really? Has anyone ever tried it from the upper left?
On the other hand, ground towing from the nose would tend to pull the glider's nose down.
- I see you've really done your homework on this issue, Donnell.
- Don't 100.00 percent of ground tows start out pulling straight forward?
- Here's a thought... Connect under the CG / below the pilot.
So one would need to limit the downward towline tension to similar values as forward towing. (A 3-g downward pull on the glider's nose could present a major control problem.)
- Duh.
- In the REAL world sailplanes connect as described above, use substantially heavier weak links for surface.
- A major control problem?
-- Stop pulling the nose down.
-- Nose down is usually the first reaction to a control problem.
-- Pity:
--- you never experienced flying with a release you could use to abort a problematic tow
--- all of our tow drivers are as fucking clueless as all of our glider pilots
Even if the towline is attached to the center of mass of the sailplane...
- Even if?
- Nobody attaches anything TO a plane's center of mass. You hook up such that the tow force vector is aligned THROUGH the center of mass. A connection on the nose for aero and on the belly under the pilot for surface both do that well enough. (Too bad you never figured that out well enough to start thinking about doing away with all that Skyting Bridle garbage you strung all over everybody's gliders.)
- There's no such thing as a 3 G pull on a sailplane 'cause they all fly with weak links half that figure. And they've been doing just fine for the past century or so without any help from you.
...so it could handle higher tow tensions when topping out, the fact that it must take off with forward towing means the weak link should be designed for forward towing.
- And the weak links they specify for surface are substantially heavier than the ones they specify for aero - as one would expect.
- You don't DESIGN weak links. (Well, I did. But 99.9 percent of the hang gliding cult just pissed all over them.) You SELECT weak link RATINGS.
If it were designed for down-towing, the weak link would be too strong for the early part of the flight.
It's not too strong if you keep the flight under some reasonable facsimile of control. You're not mandated to bring your parachute into play every time you fly just because you happen to be packing one.
In the case of hang gliders, platform towing is the only mode that consistently pulls downward throughout the whole flight when performed properly.
And it also allows the pilot to launch as a pilot - fully proned out with both hands on the control bars connector tube, tons of airspeed, and rock steady preset line tension. But unfortunately it's totally useless for training because the students learn absolutely nothing about foot launching, flying upright with their hands on the control bars, transitioning to prone after safely climbing through the kill zone.
All other forms of towing use forward pull at least during the early part of the flight.
Well... That can easily be converted to sideways with a little imagination and effort. Correcting for a crosswind seems to do the trick pretty nicely.
Therefore, they should all use a forward-pull weak link.
'Cause that's when it's really important for them to work. Yeah, we know already.
Even platform towing can revert to forward pull if done improperly.
It can also be accomplished if done properly - I know from first hand experience with Steve Wendt at Currituck 1991/05/13. Launched on cue, got majorly lulled, brake pressure was probably set too low, floated around straight behind the Suzuki Samurai for a while until Steve cranked up the pressure. Must've been using a Tad-O-Link because it was a somewhat dicey situation and it didn't break when it was supposed to. Probably just as well though 'cause I was hovering over runway pavement.
I have seen cases where the glider would launch and the vehicle would race forward at high speed to lengthen the towline before the glider could gain significant altitude.
- Yeah, I've seen that technique quite a few times. Probably was the subject of it a handful of times.
- Before the glider COULD gain significant altitude? The whole idea was to get a lot of line out and it was nobody's intention for the glider to gain significant altitude during that phase.
- The idea, if I recall / can reconstruct correctly, was to get the launch off safely, get a lot of line out, crank up the tension and slow down to slingshot the glider into the headwind gradient and have it climb steeply for the remainder of the tow and maximize efficiency for the limited runway length. And I believe this to be totally valid.
When I flew a lot of platform at Waverly, Ohio the truck would radio up for your release altitude and record it. So I believe they TOTALLY knew what they were doing on this and had the data to back it up.
This converted the down-pull into a forward-pull...
Perish the thought. That would make it like an aerotow and those things are notoriously deadly.
...even while using a down-pull weak link.
Your point being? Are we supposed to be swapping out our weak links for more Infallible ones during the tow as our angle changes?
The glider climbed out at a 45 to 60 degree angle at low altitude.
- The glider CAN'T climb out AT low altitude. It can only climb out FROM low altitude. Thus it doesn't STAY at low altitude for very long.
- AFTER they cranked up tension and slowed way the hell down.
If the payout winch had jammed for some reason...
- They would've slowed down and the glider would've pulled in and probably aborted the tow.
- Payout winches don't jam for "SOME REASON". Payout winches jam for SPECIFIC reasons. Ditto for the gliders themselves. A lot of the stuff we fly with is life and death critical and if we fail to operate and maintain it like lives depend on it we WILL kill people and the cause will be incompetence or negligence. If during a standard vanilla platform launch a winch jams "for some reason" just as the glider's lifting off the results could be pretty ugly. So why bother worrying about the winch jamming any more / as much already up with more altitude and more options?
- Compared to the foot launch crap we heard without refutation you were running at your Kingsville "training" operation? Jesus H. Christ.
...the down-pull weak link would have broken...
- ...because it would've recognized that the glider was now climbing hard in a near stall situation.
- Idiot.
...the glider would have whip-stalled...
The way they always do on the frequent occasions this occurs at higher altitudes just as gliders are getting pitched up by thermals an wind gradients.
...and the pilot would have been killed.
- Whereas if he'd been using a four G weak link he'd have just continued rocketing up with the glider still able to handle a couple more Gs until the situation stabilized. Right Donnell? Or are you gonna tell us about how much more killed he'd have been when that twelve hundred pound pull inevitably got cut loose? (Fuckin' idiot.)
- Pity you don't look into the incidents in which pilots ACTUALLY ARE whipstalled and killed. 1990/07/05 Eric Aasletten comes to immediate mind. Platform tow (constant tension payout) in known high dust devil conditions, dust devil hits and shakes truck just as glider's launching, Birrenator configured three-string increases the safety of the towing operation, brain gets pulped. Reaction from Donnell... Fuckin' ZILCH. Inconsistent with Skyting Theory so permanently shit-can it. (Second one like it that year.)
I was appauled at such an operation.
Yeah, I was pretty appauled, even pretty appetered, by the whole Lemmy Lopez situation.
But it was SOP for that group. They had done it many, many times without a mishap.
And yet all these years later we have yet to hear of a single relevant skinned knee. They were almost certainly using dangerous Tad-O-Links.
Ridgely has pulled something on the order of forty thousand tows over the course of its ten seasons. Let's be REAL generous and say that they're only breaking weak links at the rate of one per twenty flights. That's two thousand pops. The percentage of those that were desired and necessary for the safety of the flight is ZERO. So what do we learn from these numbers?
We learn that the weak links are consistently breaking before the situation becomes dangerous, exactly as they are designed and intended to do.
- The situations WERE dangerous - asshole. Lauren alone accounts for at least two severe stalls from which she was able to pull out with little to zilch altitude to spare. I watched downtubes getting trashed - one of them on a demo Talon immediately off the cart. They put extra wear and tear on all the tugs and at least one of them almost fell apart in the air and another DID fall apart in the air and total itself and its pilot.
- At the VERY BEST we have a major, expensive, prime time wasting inconvenience in which the landing and the relight go off without incident. But you're exposing two aircraft with two pilots to reruns of the two most dangerous phases of flight. And somewhere out there we may well have but not know about somebody who was and would've been fine perfectly OK on the nuisance launch but got totally demolished on the free relight. We also may have had crashes due to people cooking, getting worn down, dehydrated, overheated standing around all fuckin' afternoon waiting for all the fuckin' free relighters to stop strangling the system.
- These weren't DESIGNED by any stretch of any fevered imagination. They were pulled out of asses of total morons who didn't have the slightest fucking clues what they were doing, using, talking about.
If you really want to increase the number of weak link breaks that are deemed "desired and necessary for the safety of the flights", simply increase the weak link break point to 4 g's, or better yet, eliminate the weak link altogether.
Suck my dick, Donnell. I increased mine and others to 1.4 Gs and problems went away. Then I got sick and tired of the assholes up front dumbing down their cheap illegal crap to under what I and their tandems were using, started making noise about it, got my career ended by your fuckin' douchebag Peter Show buddies while you did and said NOTHING. Then after another few years of sickening useless Hewett Infallible Weak Link induced carnage many of us suddenly became happy with Tad-O-Links and all the associated towing safety increases vanished forever.
the ONLY PROVEN ACCEPTABLY SAFE weaklink is a string deliberately inserted into the towline which consistently breaks at a known and specified tension.
You'd be fuckin' amazed at just how much I've got you on now, Donnell. Hell, I'M fuckin' amazed at just how much I've got you on now.
Perhaps the Tost system has proven itself to you and to others to be infallable.
- They've been using the Tost system as the gold standard in sailplaning since the beginning of time and it's what all the fuckin' sailplane manufacturers use for the specs. It doesn't NEED to prove anything to any of the clueless parochial assholes who've never heard of it before.
- It's a goddam strip of metal with a hole punched through the middle. Tell me how it's gonna get less Infallible. It MAY degrade over time with use and they cover their butts by specifying a 200 launch lifespan but they just get more Infallable through stress. So you can probably pick up a few dozen of the likely safer inserts for a song.
- I got news for ya, Donnell. I've never flown a Tost anything before. I don't need to personally fly the crap outta everything to have it prove itself to me. I've flown a lot of factory fresh new model Wills Wing demo gliders. They were all PROVEN by the HGMA certification process so I don't need to worry about them being divergent or unable to handle wingovers.
- And where I REALLY DID need to go through PROVING anything was the Infallible Standard Aerotow Weak Link which I'd been insured by top Flight Park Mafia officials was twice as safe as they were telling everyone it was and continued to tell everyone it was through Dr. Trisa Tilletti 2012/06 fourteen page magazine article and where the fuck were you during any of that bullshit?
I cannot argue the point about its reliablity because I have never flown with that design.
Well if you personally haven't flown something the rest of us should remain extremely suspect.
However, you yourself commented above that "the bigger you are the faster you degrade a marginal weak link". Therefore, I get the distinct impression that your weak link degrades in time (perhaps even during a single flight).
I wasn't talking about MY weak link - dickhead. I was talking about:
Tad Eareckson - 2008/10/07 21:46:22 UTC
...the only acceptable weak link for a solo glider of any weight is a single loop of 130 pound Greenspot at the end of a bridle.
the piece o' shit one-size-fits-all precision fishing line that Davis Dead-On Straub and his Flight Park Mafia asshole buddies have inflicted on the planet - if you go back and try to read what I'm actually saying.
Whether or not it can possibly jam and become stronger than intended, I cannot say.
- Yeah, those are always HUGE problems with most commonly used weak links - jamming and becoming STRONGER with use. We've had NASA scientist and engineers working on these issues for decades but they still don't seem to be making much headway.
Use only the correct shackles; they prevent the weak link and the steel sleeve from twisting and hence an undefined increase of the breaking load
Yeah, if you're stupid enough to misuse equipment, fail to preflight there's a Darwin Effect that will often kick in. But that's a good thing.
Perhaps you can.
Ya think, Donnell? Ya think you're really worth talking to on these issues? I did back then but now... Holy shit.
More from The Fucking Manual:
Weak links protect your aircraft against overloading
Use only the weak link stipulated in your aircraft TCDS or aircraft manual
Checking the cable preamble is mandatory according to SBO (German Gliding Operation Regulations); this includes the inspection of weak links
Replace the weak link immediately in the case of a visible damage
We recommend that the weak link inserts are replaced after 200 starts; an insert exchanged in time is always safer and cheaper than one single aborted launch
Always use the protective steel sleeve
Find somebody from sailplane culture taking issue with ANY of that. But it needs Donnell's personal experience and stamp of approval for the slightest degree of legitimacy in hang gliding.
However, I do know that strings never get stronger than intended...
Do you know of any people who've been in situations in which they're PRAYING for their strings to get stronger than intended?
During the US Nationals I wrote a bit about weaklinks and the gag weaklinks that someone tied at Quest Air. A few days after I wrote about them, Bobby Bailey, designer and builder of the Bailey-Moyes Dragon Fly tug, approached me visibly upset about what I and James Freeman had written about weaklinks. He was especially upset that I had written that I had doubled my weaklink after three weaklinks in a row had broken on me.
I've heard it a million times before from comp pilots insisting on towing with even doubled up weaklinks (some want no weaklink). I tell them the same thing I'm telling you... suck it up. You're not the only one on the line. I didn't ask to be a test pilot. I can live with your inconvenience.
Then again, Russell Brown had us double up behind him after six breaks in a row at Zapata. We couldn't figure out why we had so many breaks so quickly. Maybe just coincidence.
I sure do.
...and that using a new string every flight keeps them from getting weaker.
Why would you do that? Aren't you defeating God's Plan to keep your safety margins as wide as possible at the cost of an occasional nuisance incident every now and then?
Therefore, I still find a simple string to be the least expensive, most readily available, and most easily tailored device that meets the Skyting Criteria #7: INFALLABLE WEAK LINK.
And Peter's simple Linknife to be the least expensive, most easily reachable, and most easily tailored device that meets the Skyting Criteria #6: RELIABLE RELEASE.
I'd like to get some comments on these points 'cause the AT system is totally broken on this issue. I think the first step to fixing it is to get the USHPA to amend its rules by specifying a minimum allowable weak link rating which is in accordance with that required by the FAA.
I hope my comments are what you were looking for.
They most assuredly weren't then but they sure are now. Back then my hang gliding culture assessment IQ was five percent of what it is now. And now I'm finding your comments to be mother lode GOLD.
I also hope these comments help you see that one size does not fit all.
Thank you so very much, Donnell. I've now seen the light and will go back and apologize to all my ol' Flight Park Mafia buddies and their legions of pet cocksuckers.
Different forms of towing demand different strength weak links to optimize the safety.
Really? What strength weak link was Lemmy Lopez using on the evening of 2010/10/13 to optimize the safety of his tow. Way too convenient beyond any shadow of a reasonable doubt. So how come you make zero reference to anything giving anybody the slightest clue as to what he was using so that we can all benefit from this critical foolish mistake?
If USHPA modifies the rules to optimize towing safety, it will be limiting the safety of other forms.
I so do hate when that happens. I'm hoping that what they'll do is make everything too vague and ambiguous for anybody to make the slightest bit of sense of them. That's the environment that never fails to catalyze an explosion of creativity and advancement. I see a future of safety skyrocketing, risk and expense plummeting, AT parks springing up at every available airfield around the country, the weekend cumie filled skies virtually choked with ecstatic circling gliders and reflecting enough radiation back into space to totally neutralize any alleged global warming issues. (How'd y'all make out with Harvey and Imelda by the way?{
If it tries to establish different optimum rules...
Rules? We don't need no fuckin' rules. We've got some of the strongest, most creative, most diverse opinions the world has ever seen. Top THAT, World!
...for every concievable...
And fuck that "I before E" rule. Some faggot liberal's idea no doubt.
...form of towing...
...then we'd be reduced to the level of SAILPLANING in which everyone does everything the same way all around the planet and opinions don't have snowballs' changes in Hell.
...the rules will become so cumbersome that people will ignore them.
The same way they did...
Donnell Hewett - 1980/01
No, the real reason that we Americans cannot compete against the foreigners is that we are flying obsolete equipment, and the reason we are flying obsolete equipment is because of our USHGA regulations. Look at the facts! In the Class II competition, where Americans were flying competitive equipment, two of the top five places (including first place) went to the U.S.A. But in class I where the foreigners were all using their "gimmicks," the best the U.S. could do was 18th. Really, Chris, do you have any doubts that such "gimmicks" give the foreigners that (apparently not so little) "racer's edge" that they need to win?
But why blame USHGA regulations, rather than the manufacturers, for this "obsolete" equipment? Because it's true! It has been proven time and again that regulation (and it does not matter whether it's government or "self" regulation) stifles competition, creativity, and innovation, and that the effect of regulation is frequently opposite its stated purpose. Now the stated purpose of the HGMA certification program is to insure that those gliders sold to the general public are as safe as possible. This program was established partly to "keep the government off our backs" and partly because there are certain persons among us who really do believe that such regulations actually promote safer hang gliding. In an attempt to force compliance with their certification program, USHGA has effectively limited all U.S. competition to certified gliders.
...nearly four decades ago with hang gilder certification programs. How the sport ever managed to flourish after that I will NEVER understand.
Certainly, general guidelines would be commendable, but I question whether a universal minimum allowable weak link rating in accordanc with general aviation sailplane towing would increase or decrease towing safety.
Weaklinks of 140 and 200 pounds will be available and provided by the organizers. Weaklinks provided by the organizers must be used by the competitors.
Who could possibly find the slightest issue with the state of the art as it stands today?
I've been working on this post pretty steadily for two full days and it still feels like I've just barely scratched the surface. This load o' totally lunatic and moronic shit is so deep, multilayered, interwoven that it boggles the mind. I started realizing the smell was a bit off maybe decades ago but until getting into this project which I kicked off 2019/09/22 22:59:46 UTC I still had NO IDEA.
I can't recall right now what I was researching that kicked up the Russian report copy but...
On October 13, 2010, at approximately 6:30 pm CDT, Lemuel Lopez age 45 was killed while towing a Wills Wing Falcon hang glider on a public road just north of Edinburg, Texas.
EDINBURG jumped out at me 'cause it's a major point in this next bird trip and I always familiarize the hell outta the target geography long before actually rolling. Those eight letters catalyzed a strong interest in reviewing that incident. And if it hadn't been for that somewhat amazing alignment of the stars this project might never have happened.
But that being said I don't think Donnell had a thimble's worth of piss of influence with respect to the history of the sport. Weak links five pounds over normal smooth air tow tensions were already being used on a large scale to increase the safety of the towing operation, Brian Pattenden had well before gotten the lower connection moved to the pilot, and the Brooks Bridle was flying.
And the lunatic Skyting Bridle was a quickly discarded flash in the pan.
And nobody's before ever heard of Donnell now for many years. I now feel that he was much more an inevitable product of hang gliding's total shit culture than any significant influence on it.
Much more work to be done to get the stake thoroughly pounded through his heart but I think I'm well over the hump now.
---
2020/04/06 14:20:00 UTC - Edited
Here is THE classic smoking gun perfect storm video which makes complete and total hash of every punctuation mark of everything Donnell's ever written, practiced, mandated about any and every imaginable flavor of any Infallible Weak Link in any application.
I'd had it in mind near constantly while in the recent previous posts ripping apart all the lunatic rot he's spewed.
This is a clueless rusty low Three sounding dope on a rope with at easily reachable highly Reliable Release and a stated 1.5 G mildly Fallible Weak Link behind a clueless incompetent idiot trike tug driver in glassy smooth conditions.
The only way it's humanly and aeronautically possible to induce an AT situation any worse than this is to do it the same way down low (the way Dave Farkas, Bill Bennett, Mike Del Signore and Gary Solomon, Arlan Birkett, Jeremiah did). To stall any worse than this you need to blow a free flight loop. Then you fall back onto the wing, break the keel, start working on getting the silk out, get killed anyway every other incident.
This guy has zilch skill beyond solid Two level up/down/left/right stuff - which is all anyone ever needs for anything anyway. He's too incompetent to compensate for his idiot tug driver's incompetence by speeding up and standing the motherfucker on his tail to signal him to start getting his shit together but once everything's gone totally tits up he does everything possible exactly right and gets the bubble back after ten seconds or so.
Summary... The guy on the 1.5 G Tad-O-Link who lacks the "skill" to not induce (with much help from his sleazy idiot incompetent tug driver) this worst humanly possible stall has 100.00 percent of the (low Hang Two level) skill to recover from it with absolute minimum costs of time and altitude. So go fuck yourself, Donnell.
This I in no way consider to be a lockout. A lockout is something that rather quickly happens to one as a consequence of a thermal blast rather than being slowly, deliberately, persistently flown into.
Along similar lines... We shouldn't be dignifying the "over-the-top" bullshit experienced by pro toad assholes like Dennis Pagen and Zack Marzec with the designation of lockout either. You shit-rig your glider by eliminating the primary bridle then that's the cause of your near or complete death - not the thermal blast your glider and you could've safely and easily handled with your glider fully assembled in certified configuration. There's absolutely no difference between the stupid bullshit those assholes did and what Ron Higgs did 1980/08/23 in pulling his washout struts and reflex bridle to make ground handling easier.
Now that I think of it... My very first aerotow - 1986/08/01 - was a slowly progressing over-the-top "lockout" 'cause the Cosmos was fast, the Comet was high pitch control pressure, and all AT was foot launch pro toad. Somebody cite me a single report of a two point over-the-top lockout.
If you get rolled on your ear with the two point bridle it's still a lockout but the reason it kept progressing and you got killed was because you elected to not use a Street Release.
If you want a truly foolproof release, it's got to be one that eliminates the pilot from the equation with a release that operates automatically.
There's a major near global OBSESSION with eliminating the pilot from the equation in this sport. If you get him up on a rope with Infallible Weak Links and Reliable Releases and up on the control tubes for perfectly timed flares onto the old Frisbee in the middle of the LZ you disempower him as a pilot and make him more controllable and exploitable by the national organizations and commercial interests (national organizations and commercial interests being synonyms - sorry for the redundancy).
If Donnell and Peter have ever accomplished shit as pilots I have yet to hear about and would be absolutely astonished by it. Ryan ya gotta at least credit for spectacular aerobatics but that's all glassy smooth air stuff and has zilch to do with REAL hang gliding - which is primarily thermal soaring and XC like Jonathan does.
Speed Gliding? What the fuck is that, where did it come from, where did it go? Take an aircraft that's designed to fly as slowly as possible and use it to rocket down the slope and back out of the air as quickly as possible. When was the last time anybody heard about it? When was the last time the proprietor of the worlds largest hang gliding coffee shop hooked into a glider? That motherfucker has erased and shredded the contributions of so many individuals that I can't imagine he'd wanna show up at a flying site where people could smash his fuckin' head onto one of the many sharp rocks we use to preflight test our sidewires.
This is not, never has been, never will be a pilot controlled sport 'cause it doesn't, never has, never will have anything a tiny fraction of the requisite critical mass of actual pilots in it.
Recall that Donnell had his wire cut without warning, explanation, notification anywhere to anyone from the worlds largest hang gliding community forum (it was a print magazine back then) immediately after his very first post. If there'd been any actual pilots back then:
- we'd have already been towing with the lower connection on the pilot
- the total rot that he wrote about the auto-correcting Skyting Bridle, Reliable Release, Infallible Weak Link would've been publicly cut to shreds
Stay tuned for more of decades-late aforementioned.
---
P.S. - 2019/10/06 12:35:00 UTC
This is pro toad. No bridle connection on the glider, Reliable Release, bar stuffed, spreader way down the suspension to keep the carabiner from getting crushed. Jim Keen-Intellect Rooney driving and they're still able to continue the tow.
I am sorry I have not been able to participate in the discussion on weak links that has been raging during the last few weeks, but I have been too busy to even read the postings much lest respond to them until now. Let me begin by saying that I personally appreciate Tad Eareckson's efforts to improve the SOP of aerotowing as well as his suggestion to update the Skyting Criteria. It is through efforts like his that progress is made toward safer towing.
Rather than address his and other's comments made during the recent discussion on weak links, let me remind folks that the Skyting Criteria were not developed as a model of a practical towing system. They were proposed for the purpose of defining what an ideal towing system should be in order that towing would be as safe as free flight. The first four criteria are intended to make towing accurately simulate free flight, the next four are to guarantee a safe transition to and from tow, and the last four are to identify some of the safety requirements of practical implementation.
One should remember that no towing system meets all twelve criteria all of the time. Therefore, the purpose of the Skyting Criteria is to help identify when a particular system is deviating from the ideal so that one knows when to be extra cautious and when to make compensations for those deviations.
For example, in the case of aerotowing the second criterion is accomplished by speed control rather than normal tension regulation. As long as the tug and the glider are flying at the same speed the tension remains constant. In general, this speed regulation works great as long as the air is smooth and the two pilots properly cooperate. But anything that causes a differential speed between the two craft will cause the tension to fluctuate, sometimes quite rapidly. Fortunately, the fluctuations are usually quite temporary and rarely reach the excessive values encountered in other forms of towing (such as when a payout winch jams or runs out of line). Nevertheless, compensation must be made for aerotowing's inability to meet criterion two under typical aerotowing conditions. Making the towline longer or more elastic only exasperates the differential velocities, and making it shorter increases the violation of criterion one. So the only practical solution is to recognize that the violation exists and learn to live with it. (I.e. gain sufficient practical experience under a qualified instructor to handle typical thermal conditions and to know instinctively when to release from tow as soon as the situation warrants.)
Now regarding weak links, the whole purpose of a weak link is to release the pilot from tow when he cannot do so himself and the towline tension continues to rise above the limit of safe towing. What that limit is, depends upon many factors, including pilot skill and experience as well as the type of towing and the system being used. I believe everyone recognizes that "one size weak link simply does not fit all".
For example, in the case of an ideal towing system, where the horizontal tension remains constant, a weak link of 0.5 gee will allow the glider to climb at a 30 degree angle, a 1-gee weak link will allow a 45 degree climb angle, and a 2-gee weak link will allow a 60 degree climb angle. These are also the angles a pilot will find himself flying in free-flight when the weak link breaks. Personally, I am not convinced that all hang glider pilots are qualified to recover safely from such extreme aerobatic attitudes. That is why I still recommend a 1-gee maximum weak link when towing horizontally with a good tension controlled system.
However, in the case of aerotowing, where the towline tension may vary as much as +/- 0.25 gee (or even +/- 0.5 gee) when taking off on rough or grassy terrain or when entering and leaving a strong thermal, a 1-gee weak link is going to be breaking much more often than it would on a well-regulated tension system. For most forms of towing, excessive weak link breaks usually constitute nothing more than a minor inconvenience (or a major nuisance). They simply are not a safety issue at all.
However, aerotowing also tends to violate Skyting Criteria twelve (a suitable environment) by frequently towing over terrain that is completely unsuitable for landing. In this case, a weak link break is considerably more than a minor inconvenience. It potentially places the pilot in an extremely dangerous and possibly fatal situation.
Yes, the general rule of towing is, "Get off line at the first sign of danger." However, there are exceptions to this general rule. In fact, I am sure you can imagine more than one situation where getting off line is the worst possible alternative you can take. In such cases, the towline becomes a "lifeline" rather than a "death-line." It pulls you out of danger rather than plunging you deeper into danger. Releasing low over unsuitable terrain is an obvious example of this exception.
Once again, the recognition that aerotowing frequently violates one of the Skyting Criteria requires an appropriate compensation in order to be as safe as possible. In this case, one must use a weak link that simply will not break under reasonable flight conditions and typical flight situations. When one also considers the typical tension variation encountered when aerotowing hang gliders, the conclusion is that the aerotowing weak link should be designed to break in the neighborhood of 1.5 gee (or at least somewhere within the 0.8-gee and 2-gee range specified by the FAA for towing sailplanes).
One also concludes that an aerotow pilot flying with such a weak link should have the skills to recover safely from aerobatic maneuvers greater than 45 degrees - because that is what he may well encounter when the weak link does break.
I believe that the first of these two conclusions is perfectly consistent with the point that Tad has been trying to make. And I thank him for keeping this issue before the hang gliding community.
THE SKYTING CRITERIA - 1985/08
GROUP 1. ACCURATE SIMULATION
1. CONSTANT DIRECTION
The direction of the towing force must remain essentially constant throughout every phase of the towed flight.
2. CONSTANT TENSION
The tension in the towline must remain essentially constant throughout every phase of the towed flight.
3. C-M DISTRIBUTION
The towing force must be distributed between the components of the flying system proportionally to the masses of the respective components.
4. C-M ATTACHMENTS
The towline and/or bridle must be attached as closely as possible to the effective center-of-mass of each of the components and must not be allowed to touch any other part of the flying system.
GROUP 2. SAFE TRANSITION
5. GRADUAL TRANSITIONS
The transition to and from tow as well as any variations while on tow must be gradual in nature.
6. RELIABLE RELEASES
The release devices and their activation methods must be sturdy, rapid, and reliable.
7. INFALLIBLE WEAK LINK
The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation.
8. SAFE LEARNING METHOD
The system must include a method for safely learning to use it by gradually advancing from one level of experience to the next.
GROUP 3. PRACTICAL IMPLEMENTATION
9. ADEQUATE POWER
The system must contain a source of power adequate to maintain a safe mode of flight while under tow.
10. CAPABLE CREW
The system must be operated by a crew which is adequate in number and competent in ability to see that it functions properly.
11. RELIABLE COMMUNICATIONS
The system must provide a means whereby the pilot can reliably communicate to the rest of the crew.
12. SUITABLE ENVIRONMENT
The system must be operated only within the environment and under the conditions for which it was designed.
I am sorry I have not been able to participate in the discussion on weak links that has been raging during the last few weeks...
Wouldn't a discussion on weak links that's been raging for a few weeks indicate something of a serious system-wide problem?
...but I have been too busy to even read the postings much lest respond to them until now.
Just as you will have been too busy to even read the postings much "lest" respond to them in the 2010/10/13 Lemme Lopez discussion until ever.
Let me begin by saying that I personally appreciate Tad Eareckson's efforts to improve the SOP of aerotowing as well as his suggestion to update the Skyting Criteria.
Enough to give him any covering fire ever again anywhere in any form subsequent to this post as he gets his wires cut all over the web, called the turd in the punch bowl by one of your original Skyting Newsletter buddies, his near three decades long flying career ended? Just kidding.
It is through efforts like his that progress is made toward safer towing.
- Name some other efforts like his. Name ONE.
- Do we have any evidence that any progress toward safer towing has been made subsequent to the late Eighties? If so what is it and how was it documented? And did any of it conflict with any of your current positions?
Rather than address his and other's comments made during the recent discussion on weak links, let me remind folks that the Skyting Criteria were not developed as a model of a practical towing system.
Were not developed. Was there anyone involved in developing anything other than you? I developed some pretty good shit but incorporated ideas and feedback from others and credited them.
They were proposed for the purpose of defining what an ideal towing system...
An ideal towing system with easily reachable Reliable Releases. Because the engineering and work involved in producing release systems that DON'T stink on ice makes the system less than ideal.
...should be in order that towing would be as safe as free flight.
And what data did we use to determine that free flight is inherently more dangerous than towing?
In free flight you're foot launching from a ramp with a wire crew at a slope with rocks and trees all over the place inside of one of the five second windows in which the direction, strength, and stability all become doable. And you hafta land on an old Frisbee in the middle of a big grassy field down in the valley with a perfectly timed flare if you fail to find a narrow dry riverbed with large rocks strewn all over the place in which you can get better feedback on your flare timing.
At the surface is the only place you can get hurt or killed so near the surface is the only place you really gotta worry about much of anything. Real bad things can and do happen even after you clear launch itself and when you're low away from the ridge, preferably over a field, you WILL BE going down. And gusts, wind switches, thermals, dust devils may fail to take your various concerns into account.
When you're near the surface on tow the surface is either a big fuckin' flat field or a zillion yard long runway strip and you're going UP. Ya still gotta land at some point but when you come off tow you'll be over a big fuckin' flat field or a zillion yard long runway strip.
Unless you can't access a Suitable Environment tow site you're a fuckin' moron to foot launch and you'll always have the option of wheel landing. And foot launches and foot landings have always been the most deadly shit this sport has to offer.
Summarizing... Ignoring dinosaur frame-only towing fringe activity, it's totally absurd to consider free flight operations the sterling safety standard for which we should be shooting. And the fact that you hold that mindset in this day and age...
Not buying it? Do the mental exercise of imagining the number of flights from the Big Spring US Nationals run from the White Mountains on the Owens.
The first four criteria are intended to make towing accurately simulate free flight...
Since it's actually POWERED flight why not intend to make towing accurately simulate POWERED flight?
...the next four are to guarantee a safe transition to and from tow...
- Guarantee? Do they get their money back if it doesn't work?
- Tell me why and how someone transitions TO tow. Don't people START already hooked up? If it's foot launch they resist tension until they can't anymore. If it's a SANE tow launch the glider on the wheels or dolly starts rolling when whatever's pulling him starts pulling him and the glider on the platform just blasts off when lotsa airspeed is attained.
- From tow? It's been clearly established that when using an Infallible Weak Link of 1.0 Gs or under no stall under any circumstances is possible to achieve. So if you're still on tow you're obviously under 1.0 Gs so you just pull your easily reachable Reliable Release, continue climbing a little, then do whatever.
Need TWO hands to fly the glider for some unfathomable reason?
It works best in a lockout situation... if you're banked away from the tug and have the bar back by your belly button... let it out. Glider will pitch up, break weaklink, and you fly away.
During a "normal" tow you could always turn away from the tug and push out to break the weaklink... but why would you?
Have you never pondered what you would do in a situation where you CAN'T LET GO to release? I'd purposefully break the weaklink, as described above. Instant hands free release
Problem solved. Can we get on to something that actually matters?
...and the last four are to identify some of the safety requirements of practical implementation.
Can't imagine what they'd be. Seems we've already got towing safety beaten to death. And if you add safety requirements you're increasing complexity and thus actually DEcreasing the safety of the towing operation.
One should remember that no towing system meets all twelve criteria all of the time.
Well as long as you're flying with a hook knife. It's a total no-brainer that something that works that flawlessly in any imaginable emergency situation well be able to handle the routine stuff in its sleep.
Therefore, the purpose of the Skyting Criteria is to help identify when a particular system is deviating from the ideal...
As defined by Dr. Lionel D. Hewett without a whisper of disagreement from anyone anywhere.
...so that one knows when to be extra cautious and when to make compensations for those deviations.
Any possibility that any of the Criteria are total rubbish and the deviations are totally spot on?
For example, in the case of aerotowing the second criterion is accomplished by speed control rather than normal tension regulation.
- What's NORMAL tension regulation? I'm gonna say that the vast majority of sailplaning is and always has been AT and it's a total no-brainer that that's the case with hang gliding. So I would contend that AT is the normal, more effective and efficient tension regulation. With surface - including platform, you're dealing with constantly changing:
- tow angle
- line sag and drag
- glider pitch attitude
With aero you just floor it and climb. And only rarely (see below) do power adjustments need to be made.
- Can you show me a video of an aerotow in which tension / speed variations themselves are causing problems? On one of my pulls at Ridgely I got into an oscillation cycle at maybe 150 to 200 feet. The tug violated the second criterion and slowed down until I got my shit back together then cranked it back up and we continued merrily on our way.
As long as the tug and the glider are flying at the same speed the tension remains constant.
Who the fuck cares? You can get up behind a 582. You can get up faster and better with more safety margin behind a 914. When the 914 kicks in the turbocharger you can't really tell without looking at a tension gauge. The tension fluctuates substantially all the fuckin' time when you're bouncing along through thermal turbulence and it's not the slightest big fuckin' deal for either plane (unless there's a goddam pain in the ass standard Infallible Weak Link in the mix anyway).
In general, this speed regulation works great as long as the air is smooth and the two pilots properly cooperate.
- Who the fuck wants to tow up in SMOOTH AIR?
- TWO pilots? In what cave have you been living in all this time? There's only ONE PILOT and that motherfucker doesn't hafta cooperate with anyone or anything. The guy on the hang glider is a PASSENGER just getting dragged along in accordance with what the PILOT says and does.
And if you wanna do ANYTHING to enhance the safety of towing then Step One is to get those fucking douchebag under some kind of control. Those assholes crash and kill people and you've never done shit about it. And they use your goddam Infallible Weak Link criterion to justify what they do.
But anything that causes a differential speed between the two craft will cause the tension to fluctuate, sometimes quite rapidly.
So what? When we free fly through turbulence our airspeed and loading fluctuates, sometimes quite rapidly. Thermal soaring aircraft are SUPPOSED to be flown in these conditions.
Fortunately, the fluctuations are usually quite temporary...
Yeah Donnell. That's what a fluctuation is. If it's not quite temporary it's a big thermal or area of sink. And if it's the former we say hallelujah, pin off, and crank and bank.
...and rarely reach the excessive values encountered in other forms of towing (such as when a payout winch jams or runs out of line).
We don't talk about payout winches jamming or running out of line for the same reason we don't talk about sidewire failures, unhooked launches, or flying into trees.
Nevertheless, compensation must be made for aerotowing's inability to meet criterion two under typical aerotowing conditions.
Typical aerotowing conditions:
- are ALWAYS thermal. Otherwise there's absolutely no reason to tow - save for training. And we're already qualified so fuck sled rides.
- ALWAYS include the possibility of something going nuclear. Pro toad tandem aerotow instructor Zack Marzec learned this the hard way at Quest on the afternoon of 2013/02/02. So every flight we make necessitates that we be equipped and prepared to safely deal with that situation at a bare minimum. And the Skyting Criteria don't come anywhere close to cutting it. The fuckin' Skyting Criteria aren't the solution - they're the problem.
Making the towline longer or more elastic only exasperates the differential velocities...
More elastic?
- We're towing with SPECTRA. That's at least ONE thing those dickheads got right.
- Elasticity has absolutely no place anywhere in towing of any kind.
- Have you talked to Peter about this?
...and making it shorter...
Shorter than WHAT? There are tradeoffs as you shorten and lengthen towline lengths. 250 feet seems to be a sweet spot, I've never had a problem with it, I've never heard about anybody from either end having a problem with or complaining about it, let's leave it alone. We've got WAY bigger issues to worry about.
...increases the violation of criterion one.
Constant Direction? I got news for ya, Donnell... Pretty much everything about AT violates the crap outta Criterion One. As soon as we get up a bit the tug WILL turn. It wants to stay over the runway so's it can get back for the next launch quickly, efficiently, cheaply and it WILL start hunting for thermals so it can drop you off happy at 1500 rather than 2500 feet. Both of us get what we want.
And we have zilch problems with turns. Makes one wonder just a bit about the validity of Criterion One. Which in turn makes one wonder just a bit about the entire package.
So the only practical solution is to recognize that the violation exists and learn to live with it.
We'll see if we can manage. My understanding is that if you wanna turn to the right you shift your weight to under the right wing. But let me check on that to make sure and get back to you.
No wait...
Donnell Hewett - 1982/09
In addition to the above mentioned roll and yaw tendancies, there is some sideways force on the pilot due to the body line. This is illustrated below:
As can be seen, this sideways force tends to pull the pilot over to the correct side to make the glider turn naturally in the proper direction.
You just let the sideways towline force tend to pull you over to the correct side to make the glider turn naturally in the proper direction. So you really don't hafta do anything.
...(I.e. gain sufficient practical experience under a qualified instructor to handle typical thermal conditions...
- I didn't do any of that shit, Donnell. I learned to fly, largely on my own (the instruction has always been worth shit anyway) soaring the dunes in thermal crap. When the right wing went up I shifted right. After a bit that became reflexive. By the time I thought about it I'd already done it. When I started aerotowing I just followed the tug. It wasn't rocket science.
- AT instructors are useless incompetent parasites. Zack Marzec and his buddies proved that beyond the slightest shadow of a reasonable doubt on the afternoon of 2013/02/02 and in the aftermath. And if you disagree then name ONE. And don't even think about submitting your own name.
- The typical thing about typical thermal conditions is that they can't be assumed to be typical. Therefore...
The strength of the weak link is crucial to a safe tow. It should be weak enough so that it will break before the pressure of the towline reaches a level that compromises the handling of the glider but strong enough so that it doesn't break every time you fly into a bit of rough air. A good rule of thumb for the optimum strength is one G, or in other words, equal to the total wing load of the glider. Most flight parks use 130 lb. braided Dacron line, so that one loop (which is the equivalent to two strands) is about 260 lb. strong - about the average wing load of a single pilot on a typical glider. For tandems, either two loops (four strands) of the same line or one loop of a stronger line is usually used to compensate for nearly twice the wing loading. When attaching the weak link to the bridle, position the knot so that it's hidden from the main tension in the link and excluded altogether from the equation.
IMPORTANT - It should never be assumed that the weak link will break in a lockout.
ALWAYS RELEASE THE TOWLINE before there is a problem.
...you can't afford to fly a typical weak link for a typical pilot on a typical glider.
...and to know instinctively when to release from tow as soon as the situation warrants.)
- Everyone and his fuckin' dog knows instinctively when to when to release from tow as soon as the situation warrants. The problem is that down low when shit actually matters it was five seconds ago and now you can't do anything anyway because you're gonna die sooner if you attempt to actuate your easily reachable Reliable Release.
- Why?
GROUP 2. SAFE TRANSITION
7. INFALLIBLE WEAK LINK
The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation.
You've got an Infallible Weak Link which will infallibly and automatically release the glider from tow whenever the towline tension exceeds the limit for safe operation. If the situation warrants the towline tension has quite obviously exceeded the limit for safe operation. And an Infallible Weak Link is EXTREMELY Infallible and if it's already got one or two tows on it it's even more Infallible. Not really seeing any possible problem here.
Now regarding weak links...
Done that already, Donnell.
...the whole purpose of a weak link is to release the pilot from tow when he cannot do so himself...
I can't begin to imagine a situation in which I can't release from tow myself. If I can't even release from tow myself how are you expecting me to be able to navigate back to the LZ, fly the approach, nail the old Frisbee with a perfectly timed flare. How come there's no fuckin' Skyting Criterion specifying a requirement of a pilot who can always release from tow? 'Cause the whole fuckin' Skyting can of worms is totally shit-rigged?
...and the towline tension continues to rise above the limit of safe towing.
IT CAN'T. What part of "Infallible" are you having so much trouble understanding?
What that limit is, depends upon many factors, including pilot skill and experience as well as the type of towing and the system being used.
I hadn't considered that. So the Infallible Weak Link gauges factors like pilot skill and experience as well as the type of towing and the system being used, crunches the numbers, calculates the precise figure at which it needs to succeed - plus or minus 1.5 percent. Close fucking enough.
I believe everyone recognizes that "one size weak link simply does not fit all".
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.
At the 2008 Forbes Flatlands Greenspot for the first time was used as the standard weaklink material (thanks in large part to the efforts of Bobby Bailey). We applaud these efforts to improve the safety of aerotowing by using a better weaklink material.
Right. And your position on the Easter Bunny is...?
For example, in the case of an ideal towing system, where the horizontal tension remains constant, a weak link of 0.5 gee will allow the glider to climb at a 30 degree angle, a 1-gee weak link will allow a 45 degree climb angle, and a 2-gee weak link will allow a 60 degree climb angle. These are also the angles a pilot will find himself flying in free-flight when the weak link breaks.
Why would ANY weak link break if the glider's climbing safely...
..at a 60 degree climb angle? The towline tension limit for safe operation obviously hasn't been exceeded.
Personally, I am not convinced that all hang glider pilots are qualified to recover safely from such extreme aerobatic attitudes.
- I'm with ya there, Donnell. Hell, I'm not even convinced that ANY pilot, myself included, can safely recover from a 0.8 success if things go a bit tits up at the wrong time on a bumpy launch.
- And you, personally, are the one guy in all of aviation on the planet we need to convince because you were the first to really understand what a weak link was and should be. And it's such a complex and technical issue that there's not one single individual to whom you can hand things off if you get tied up at work for several weeks.
- Pity you haven't yet been able to get the FAA to come around to the correct way of seeing things. 'Cause their regs have yet to be properly tweaked. Their legal minimum isn't far down from your preferred maximum. And their max is over all manufacturer specs and twice your preferred. And four years ago they pulled hang gliders in under them.
That is why I still recommend a 1-gee maximum weak link when towing horizontally with a good tension controlled system.
- If it's a good tension controlled system why the fuck does a weak link matter in the least? A weak link can only be of any use when the tension control is total crap.
- Unless all you wanna do is ground skim there's no such thing as good tension controlled system. If you're doing ground skimming it's scooter training for new Hang Zeroes and a fuckin' weak link is about as useful as a hook knife or parachute. Otherwise it's aero and the tension can and does bounce all over the place. And people fairly frequently find themselves in situations in which the absolute last thing they want is an Infallible Weak Link success. So just how much AT experience do you have under your belt. Pretty good bet it's total fuckin' zero...
I've heard it a million times before from comp pilots insisting on towing with even doubled up weaklinks (some want no weaklink). I tell them the same thing I'm telling you... suck it up. You're not the only one on the line. I didn't ask to be a test pilot. I can live with your inconvenience.
The people who ACTUALLY DO THIS a lot don't seem to be sufficiently concerned about the whipstalls into which my Tad-O-Links will force them.
However, in the case of aerotowing, where the towline tension may vary as much as +/- 0.25 gee (or even +/- 0.5 gee) when taking off on rough or grassy terrain...
- We're foot launching right? Skyting Theory doesn't recognize the existence of dollies. So how could the terrain possibly matter?
- Rough or grassy? Same effect.
- Whatever we take off from is SMOOTH. Dragonflies may not give much in the way of flying fucks about the gliders but they don't want to beat themselves up on crappy strips and runways.
- We take off from grass, dirt, pavement. If you take off from pavement the absolute last thing you want anywhere in your system is an Infallible Weak Link. Pete Lehmann getting his stupid knee sanded down to the bone was what FINALLY fatally cracked the Standard Aerotow Weak Link scam. It was gasping along on borrowed time for another eighteen months before Zack Marzec drove a permanent stake through its heart.
...or when entering and leaving a strong thermal, a 1-gee weak link is going to be breaking much more often than it would on a well-regulated tension system.
- If it's a really well regulated tension system a one G weak link WON'T BREAK.
- An aerotow is a perfectly well regulated tension system as far as the people who actually fly it in the real world are concerned. If it weren't it wouldn't be sustainable. And it gets off thousands upon thousands of tows without issue EXCEPT FOR those in which your fucking Infallible Weak Link increases the safety of the towing operation. Lockouts are rare and damn near always at altitude where they don't really matter. Ridgely went through seventeen full seasons without one single low level lockout that wasn't pilot induced. And we don't gear and equip for pilot induced shit. We don't all fly with scuba tanks because somebody went down in the Pacific off of Oregon.
For most forms of towing, excessive weak link breaks usually constitute nothing more than a minor inconvenience (or a major nuisance).
- For ALL forms of towing ANY weak link break is a MAJOR DANGEROUS EXPENSIVE SYSTEM FAILURE. It's a major very valuable time eating pain in the ass to set up a tow with fifteen gliders standing in line during the short soaring window.
- ANY weak link break is EXCESSIVE. Talk to the fuckin' sailplane guys ferchrisake.
inconvenience/nuisance pop got a veterinary surgeon's arm broken in three places and permanently ends his hang gliding career because the recovery phase ended back on the fuckin' runway.
- So I guess these excessive inconvenience/nuisance breaks are all happening because the gliders have pitched up unacceptably steeply. But one hundred percent of them are being safely recovered from because Skyting Criterion 7 dictates that you will always safely recover well before the ground comes up. Absolute total fucking BULLSHIT.
They simply are not a safety issue at all.
Nah, they never are for the guy at the front end of the line - which is the only place at which you plant yourself in these operations.
However, aerotowing also tends to violate Skyting Criteria twelve (a suitable environment) by frequently towing over terrain that is completely unsuitable for landing.
Right. We never climb out high enough at the time we leave the field to be able to make it back to the field when our Standard Aerotow Weak Link increases the safety of the towing operation.
I probably witnessed fifty broken weak links this summer at Highland.
The treetops around all these operations are littered with the remains of inconvenienced gliders and it's a real pain in the ass to safely extract/recover the pilots. And lotsa times when the tugs lose power they have even less chance to get back to the field 'cause of their relatively crappy glide ratios so they gotta blow their ballistics and the tug's virtually always a write-off.
It is ASTONISHING how TOTALLY CLUELESS this asshole is about real world towing. Assuming some minimal degree of sanity he's never seen an AT operation of any kind, sailplanes included, hasn't watched a single video, can't form a mental image of one - or we've got way bigger issues. Fuckin' totally certifiable though either/any way.
In this case, a weak link break is considerably more than a minor inconvenience. It potentially places the pilot in an extremely dangerous and possibly fatal situation.
Fuck yeah. Here come the trees. Good thing I had my Infallible Weak Link to minimize my recovery time and give me a fighting chance to get back inside the field.
Yes, the general rule of towing is, "Get off line at the first sign of danger."
Who made up this general rule? What were his qualifications? On what data is it based? Does getting your nose pitched up count as a sign of trouble? Can we find this general rule somewhere Dan Poynter's book or did it only come about after we moved the lower connection off of the control bar and onto the pilot?
However, there are exceptions to this general rule. In fact, I am sure you can imagine more than one situation where getting off line is the worst possible alternative you can take.
Well yeah, but a general rule is still a rule and must be followed to the letter.
In such cases, the towline becomes a "lifeline" rather than a "death-line." It pulls you out of danger rather than plunging you deeper into danger. Releasing low over unsuitable terrain is an obvious example of this exception.
So if you're locking out - which would be the only situation in which you should and need to release - don't release 'cause then you'll hafta land on unsuitable terrain. Trees, rocks, rattlesnakes...
Once again, the recognition that aerotowing frequently violates one of the Skyting Criteria requires an appropriate compensation in order to be as safe as possible. In this case, one must use a weak link that simply will not break under reasonable flight conditions and typical flight situations. When one also considers the typical tension variation encountered when aerotowing hang gliders, the conclusion is that the aerotowing weak link should be designed to break in the neighborhood of 1.5 gee (or at least somewhere within the 0.8-gee and 2-gee range specified by the FAA for towing sailplanes).
So then you continue the lockout to twice as many Gs and the unsuitable terrain will take pity on you due to the severity of the ensuing stall and will open up a fifteen second suitability window to give you a fair shot at coming out OK. And obviously this won't happen if you release at the first sign of trouble at 0.6 Gs.
One also concludes that an aerotow pilot flying with such a weak link should have the skills to recover safely from aerobatic maneuvers greater than 45 degrees - because that is what he may well encounter when the weak link does break.
Not a whip-stall? 'Cause in your last post a bit over three weeks ago you said:
Donnell Hewett - 2008/10/14 00:49:34 UTC
6686
I have seen cases where the glider would launch and the vehicle would race forward at high speed to lengthen the towline before the glider could gain significant altitude. This converted the down-pull into a forward-pull even while using a down-pull weak link. The glider climbed out at a 45 to 60 degree angle at low altitude. If the payout winch had jammed for some reason, the down-pull weak link would have broken, the glider would have whip-stalled, and the pilot would have been killed.
So what you're ACTUALLY saying is that an aerotow pilot flying with such a weak link should have the skills to recover safely from aerobatic maneuvers greater than 45 degrees and that any such maneuver greater than 45 degrees WILL BE a whip-stall which WILL KILL the pilot totally regardless of any skills he may have.
GOTCHYA - motherfucker.
I believe that the first of these two conclusions is perfectly consistent with the point that Tad has been trying to make.
- You BELIEVE WRONG(ly).
- Tad isn't TRYING to make ANY points. There's only one point and Tad HAS MADE it. Well, actually...
Tost Flugzeuggerätebau
Weak links protect your aircraft against overloading.
Tad's just bringing a long established point to the attention of all you useless stupid shits.
And I thank him for keeping this issue before the hang gliding community.
Oh good.
- I've kept before the hang gliding community. In this case just the inbred little cult segment of the hang gliding community that meets with Peter's approval.
- The way Doug Hildreth kept the issue of the hook-in check in front of the hang gliding community for over a dozen years with ZERO instructors ever complying with the u$hPa rating requirement and evidence of not one single flyer ever converting in response.
- And yet when I look on Peter's website at a copy of Donnell Hewett's original 12 elements of a good tow system TODAY I see:
These are Donnell Hewett's original 12 elements of a good tow system. They are as viable today as they were in the early 80's when he wrote them.
#7: INFALLIBLE WEAK LINK
The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation. (There is always the possibility something unexpected can happen. Breaking point should be appropriate for the weight and experience of the pilot, not to exceed 1G - sum of all towed parts.)
So you never actually did SHIT in response to his keeping this issue before the hang gliding community. Keeping this issue before the hang gliding community was way above and beyond the call of duty. Throw this asshole a bone and hopefully he'll shut the fuck up and go away.
From the Peter Show archive all from three of the total of four of Donnell's posts all the eleven paragraphs in which forms of "stall" and/or "recover" are mentioned in relevant contexts.
Donnell Hewett - 2005/02/08 23:28:13 UTC
4597
6. The appropriate strength of a weaklink does not depend upon weather conditions or the flight attitude of the glider (turbulence, wind gradient, lockouts, etc.). It is impossible to design a weaklink to release the pilot when he looses flight control because there is no correlation between towline tension and flight control. (A pilot may be in perfect control under high tension but out of control under low tension.) A weak link can only be designed to release the glider under the worst possible conditions before the towing forces exceed the limits of safe recovery when the weaklink breaks.
Donnell Hewett - 2008/10/14 00:49:34 UTC
6686
In my opinion, the sole purpose of a weak link is "to allow the aircraft to recover safely when the weak link does break". Obviously, if the aircraft is the weak link, recovery is impossible. But even if the aircraft does not break, recovery may still be extremely dangerous.
In the early days of towing hang gliders, the mantra was "Never use a weak link because it always breaks at the worst possible time and when it does break it only increases the danger of the situation." They tried to beaf everything up so that nothing would break. But something would always break when the towing forces became strong enough. And when that something broke (even if it was not the glider), someone would die. Imagine a 4 g towline pulling forward on a the center-of-mass of a pilot-glider system shortly after take-off. This would pitch the nose of the glider upward at some 80 degree angle above normal flight (arctan 4). If the towline or weak link broke under those conditions, the glider would whip-stall at that low altitude and plumet into the ground. And if the towing were not CM or if the glider were in a lockout, the situation would probably be even worse.
I am sorry you find those two statements mutually exclusive. The key word in the first paragraph is "flight" and the key word in the second is "recovery." A pilot may well be able to control the glider in flight with a 10 g towing force. But very few pilots could control the glider immediately after that 10 g towing force suddenly became a 0. It would take an expert aerobatic pilot both time and altitude to get the glider back under control. But most non-aerobatic pilots would find it almost impossible to recover from a whip-stall safely, especially if it occurred near the ground.
There is another characteristic that distinguishes aerotowing from other forms of towing. Any pilot that is awarded an AT rating or allowed to solo must have demonstrated the ability to control the glider under normal tow operations. This includes the skill to keep the glider properly positioned behind the tug in typical thermal conditions. Such a skill level is considerably greater than that of rank beginners learning to hang glide by towing. Clearly, beginners just learning to tow do not have the ability to recover from a 1.5 g weak link break. They should be flying with a towline tension around 0.5 g and have a weak link that breaks somewhere around .75 g - surely no greater than 1 g.
On the other hand, any rated tow pilot should have the skills and ability to recover from a 1.5 g weak link break (or even a 2 g break). So in the case of aerotowing, I tend to agree with your above statement. However, in general I still believe that the weak link break strength should be adjusted to pilot skill for hang-1 and hang-2 pilots.
Again, everyone piloting a sailplane solo and everyone rated to pilot a hang glider solo has similar skills. Certainly they have mastered the minimum safe skills to pilot the gliders under typical conditions. Therefore, a weak link that breaks anywhere in the 0.8 to 2 g range should be appropriate. Somewhere in the middle (about 1.4 g) may even be more appropriate. However, I see no good reason for everyone to shoot for the exactly that same value. Anyone skilled enough to recover from a 2 g break can recover from a 0.8 g break. They do not need to limit themselves to 1.4 g. However, when they get above 2 g's they are beginning to push the envelope of safety. And the farther they get below 0.8 g's they more they are asking for unexpected pre-mature releases over potentially dangerous terrain.
Increasing the tension pulling forward increases the glider's air speed until the nose can no longer be kept down. (The effect of a 1-g forward tension is the same as if the glider were being flown in free-flight at a downward angle of 45 degrees. A 2-g forward tow tension is equivalent to a 60 degree dive. No hang glider can maintain such dive angles for very long. Their increasing air speed will soon force them to start pulling up out of the dive.) When the nose comes up the forward speed of the glider will decrease and the position of the glider will become dangerously high possibly forcing the tug down. Unless the tug also slows down, the difference in air speed will increase the tension even more as the situation worsens until either the weak link breaks or one of the pilots release. Then the issue becomes that of how to recover safely. A weak weak-link prevents this situation from becoming as extreme as a strong weak-link allows.
In the case of hang gliders, platform towing is the only mode that consistently pulls downward throughout the whole flight when performed properly. All other forms of towing use forward pull at least during the early part of the flight. Therefore, they should all use a forward-pull weak link. Even platform towing can revert to forward pull if done improperly. I have seen cases where the glider would launch and the vehicle would race forward at high speed to lengthen the towline before the glider could gain significant altitude. This converted the down-pull into a forward-pull even while using a down-pull weak link. The glider climbed out at a 45 to 60 degree angle at low altitude. If the payout winch had jammed for some reason, the down-pull weak link would have broken, the glider would have whip-stalled, and the pilot would have been killed. I was appauled at such an operation. But it was SOP for that group. They had done it many, many times without a mishap.
Donnell Hewett - 2008/11/05 21:23:39 UTC
6744
For example, in the case of an ideal towing system, where the horizontal tension remains constant, a weak link of 0.5 gee will allow the glider to climb at a 30 degree angle, a 1-gee weak link will allow a 45 degree climb angle, and a 2-gee weak link will allow a 60 degree climb angle. These are also the angles a pilot will find himself flying in free-flight when the weak link breaks. Personally, I am not convinced that all hang glider pilots are qualified to recover safely from such extreme aerobatic attitudes. That is why I still recommend a 1-gee maximum weak link when towing horizontally with a good tension controlled system.
One also concludes that an aerotow pilot flying with such a weak link should have the skills to recover safely from aerobatic maneuvers greater than 45 degrees - because that is what he may well encounter when the weak link does break.
When it's "stall" - three occurrences - it's always a "whip-stall" and in conjunction with use of a Tad-O-Link. Two are fatal whip-stalls and the other almost certainly is.
When it's "recover" - thirteen references...
- Four references to the SAFE recovery guaranteed by use of a 1.0 or safer Hewett Infallible Weak Link.
- Nine references relating to Tad-O-Links ranging through substantial skill and experience required for survival up to no freakin' possibility 'cause you've just torn your glider apart.
It is STILL IMPOSSIBLE to STALL on a Hewett Infallible Weak Link. You're ALWAYS "RECOVERING". And recovery by definition excludes any possibility of slamming back into the fuckin' runway.
For some unfathomable reason your Skyting Criteria don't seem to have yet gotten through to the sailplane crowd...
Their solution to this one is neither to use a more Infallible Weak Link to leave the glider more controllable when the Infallible Weak Link inevitably succeeds nor a more skillful pilot in order to more skillfully and quickly recover from the whip-stall. It's for the moderately skillful pilot to not stand the fuckin' glider on its fuckin' tail just off the runway.
Or, now that I think about it...
That's a dedicated weak link success - nothing to do with the towline or leader. And there was no reason for it to have broken. The glider wasn't out of control, headed for being out of control, being stressed. You can see the starboard wing and it isn't being flexed in the least - flex is identical to what it was when the plane was rolling up to speed still on the runway. The glider was just happily and safely going skyward just like Graziano Mele:
at Mike Safety-Book/Dead-Eye Robertson's world class Toronto operation - 'cept not as steep.
So maybe you've totally gotten through to them and what we're actually seeing - ignoring the text - is a Hewett Infallible Weak Link that:
- infallibly and automatically releases the glider from tow when the towline tension has exceeded the limit for safe operation
- releases the glider under the worst possible conditions before the towing forces exceed the limits of safe recovery when the weaklink breaks *
---
* Provided, of course, that you at this point have enough airspeed and/or altitude for safe recovery.
So I could easily photoshop out the text...
...and present this graphic as an illustration of:
Tost Flugzeuggerätebau
- Weak links protect your aircraft against overloading.
- Use only the weak links stipulated in your aircraft TCDS or aircraft manual.
- Checking the cable preamble is mandatory according to SBO (German Gliding Operation Regulations); this includes the inspection of weak links.
- Replace the weak link immediately in the case of visible damage.
- Always use the protective steel sleeve.
- We recommend that the weak link insert are replaced after 200 starts: an insert exchanged in time is always safer and cheaper than one single aborted launch.
not to mention:
Manned 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
Another point of ambiguity... The glider's still in pristine shape when we see it in the last frame. Beyond that frame we can only speculate about any outcome. And speculation about anything - like the color of the helmet the guy was flying - is clearly and strictly prohibited by the United States Hang Gliding and Paragliding Association, Inc. For a first offense the pilot is warned with a lifetime expulsion. So one's guess would be as good as anyone else's.
Donnell Hewett - 1985/08
7. INFALLIBLE WEAK LINK
The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation.
The system must include a weak link which will infallibly and automatically release the glider from tow whenever the tow line tension exceeds the limit for safe operation. (There is always the possibility something unexpected can happen. Breaking point should be appropriate for the weight and experience of the pilot, not to exceed 1G - sum of all towed parts.)
The limit for safe operation... What you SHOULD'VE said was the limit for A SAFE TOW. 'Cause all tows which don't end in impact with the glider still connected are safe. When you say safe OPERATION you hafta include...
Due to the rough conditions weak links were breaking just about every other tow and the two tugs worked hard to eventually get everyone off the ground successfully.
Last year, at LMFP I saw an incident in aerotow that resulted in a very significant impact with the ground on the chest and face. Resulted in a jaw broken in several places and IIRC some tears in the shoulder.
I witnessed the one at Lookout. It was pretty ugly. Low angle of attack, too much speed and flew off the cart like a rocket until the weak link broke, she stalled and it turned back towards the ground.
...victim's tow was perfectly safe. But the increase in the safety of the towing operation afforded her by her Infallible Weak Link contributed to her less than stellar landing.
Lemme Lopez's tow was safe at the time he finally was able to get his make-shift "Linknife" to function - while flying his glider with the other hand. There was no way it couldn't have been because his make-shift "Infallible Weak Link" was obviously still intact until he cut it.
So when you say "the limit for safe OPERATION" you gotta AT A MINIMUM consider the period during which the flight is being negatively affected by the increase in the safety of the towing operation. Nuisance/Inconvenience/Stall recovery obviously but also the fact that the dope has less to zilch in the way of choice about where, when, how to land. If the tow had gone to eight hundred feet he could've:
- set up a comfortably DBF approach
- landed on the grass rather than on the pavement or in the soybeans
- hung out a little bit to avoid the cycle that was just breaking off
- stayed up for three hours until after the thermal activity had quit
Then if you wanna look at that moronic crap that Adam Parer described. Two launch efforts in great thermal / crap safety conditions for every one that gets up successfully. Two planes at risk for extra doses of the two most dangerous phases of flight - even without the lunatic crap with which you've fitted the glider.
This bullshit was all happening and would've all happened without your contributions but you were the first to put things in print and endow it with a facade of academic legitimacy. You took all the credit for moving the lower connection from the frame to the pilot and conspicuously never even acknowledged what had been already done earlier and fifty times BETTER in the UK - which was the height of sleaziness. So you totally own this one till hell freezes over.
Every tension limiting device discussed up to now consists of mechanical components, has a limited range, or relies upon human operation.
Everything regarding ALL aircraft consists of mechanical components, has limited ranges, relies upon human operation. What's your fuckin' point?
Every one of these tension limiting devices is subject to failure.
Everything we go up with is subject to failure. That's why we have maintenance schedules and preflight inspections. We can't afford to go up with stuff that matters that's gonna fail and we don't really worry about the assholes who do go up with stuff that matters that fail.
Please correct me if I am wrong...
Why bother? People have corrected you tons of times when you're wrong and it's never made the slightest difference.
...but it is also my understanding that there are a large number of tow pilots today...
So we have a large number of tow pilots today? How'd they ever manage to build up and maintain such a large population without doing everything in compliance with what you're in the process of defining?
...who are depending upon smooth air, rope stretch, boat speed, mechanical devices, and ground crews to provide the tension limitation control for their flights.
- Smooth air isn't worth towing in. Talk to some flatland sailplane pilots.
- Rope stretch does the polar opposite of what you want for tension limitation control. But you're gonna use it exclusively anyway.
- What mechanical devices? Engines? Yeah that's pretty much how we maintain tension control.
- Ground crews? Does that include a driver? See 3 above.
Well, in the author's opinion that is just not good enough.
The author? Singular? So none of the other members of your team shared your opinion? I'm guessing that's the case 'cause we've never heard a single one of them speak up on the issue. How come?
Skyting requires the use of an infallible weak link to place an absolute upper limit to the towline tension in the unlikely event that everything else fails.
In the UNLIKELY event that EVERYTHING else fails. Driver, winch, towline, bridle, primary release, secondary release, hook knife, pilot, pitch control, parachute, weather forecast... OK. Sounds like an Infallible Weak Link is your ticket to success.
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."
- So they're just arguing. There's zero actual foundation for anything.
- The worst possible time is when you NEED the weak link to break and when it's supposed to and WILL. It won't do any good below a couple hundred feet but if you've got enough air below you it'll probably function to make sure you have an intact plane to fly away with.
- Climbing hard in a near stall situation isn't the WORST possible time - it's the BEST possible time. It's the whole fucking purpose of towing.
- You're CONSTANTLY in a near stall SITUATION on tow with an Infallible Weak Link. If you lose the rope at ANY tension in which you're climbing at a rate to make it worth having gotten out of bed YOU WILL STALL. But if you DON'T have total shit equipment you're not anywhere CLOSE to actually STALLING. If you're climbing hard you are - BY DEFINITION - at an optimal ANGLE OF ATTACK.
- When you're flying a tug or a Cessna for either's intended purpose and you lose your engine YOU WILL STALL. That's why we hafta make sure that our engine will ALWAYS do what we want it to. The Hewett strategy is that instead of making sure we have our shit together on our engine we should use one just capable of getting us off the runway two or three attempts out of four and to keep the oil level low so it's more likely to seize if we attempt to climb out too quickly.
- Nobody who's functioning as a PILOT has EVER been saved by a weak link. Weak links only save aircraft and only at the second they succeed. What happens in the subsequent seconds is anybody's guess but as a general rule it's not very good.
- Nobody's ever been "injured" because of a weak link he's using as a weak link. If he's been "injured" it's because a good bit ago he ceased functioning as a pilot. A pilot should worry about this scenario about as much as he should worry about flying into the tree in the middle of the cow pasture.
- Getting saved by an actual weak link is a lot like getting saved by a parachute.
-- It's not gonna work a lot of the time and will be pretty much totally useless if you're low.
-- Unless you've been flown into by some asshole you've probably done something really stupid to put yourself in a situation in which your life depends upon it.
-- Legitimate relevant incidents are pretty much nonexistent.
- "Argument" - singular so "More people have been injured because of a weak link than saved by one." is a STATEMENT. So I guess you're just gonna totally dismiss it 'cause it's incompatible with Skyting Theory.
- So it shouldn't be all that fuckin' difficult to cite one of the many incidents you've undoubtedly heard as the opposition folk are supporting their positions with ACTUAL DATA. So we don't get to hear a single one of them? See above. But that's OK 'cause we have enough fatality reports from the magazine in which the glider's climbing normally at normal tension when he experiences a nuisance.
- No pilot has ever been saved by a weak link. Assholes who've survived lockouts when a weak link kicked in were passengers with Reliable Releases.
Well, I for one have been saved by a weak link...
Well OK then. Those eleven words are all we'll ever need to hear about the incident. I was once saved at the Cromwell Baltimore Light Rail Station by a guy who helped me push my car to jump start it when the battery was mostly dead. If it hadn't been for him I'd have had to wait for some other guy to show up and save me. You don't say your life was saved.
If my life had been saved by a backup loop and I were arguing for more widespread use of backup loops I'm having a hard time imagining my not writing a paragraph describing how my primary failed because I hadn't replaced it at the usual six month interval. And funny we have a very extensive detailed account of you breaking your arm when your Infallible Weak Link failed to save you with zilch mention of the fact that your Infallible Weak Link failed to save you. Don't recall your Reliable Release being of that much use either - or you mentioning that detail either.
Not buying it, Donnell. I've seen the misleading crap you tried to pull on the Lemmy Lopez report and this totally fits the pattern.
...and would not even consider towing without one.
- Name the people in this sport who'd consider flying without a backup loop and locking carabiner.
- After Jeff Bohl got splattered by his Tad-O-Link at Quest there wasn't ONE SINGLE INDIVIDUAL who even SUGGESTED a return to something a pound back in the direction of the original Davis Link. What we DID see was a lot of interest in the Kaluzhin release until after the Flight Park Mafia sabotaged the effort. If one has a half functional brain one doesn't come within a second and a half of certain death in a low level lockout without at least starting to look at some of the options that DON'T stink on ice. In the entire history of your 43 plus year participation in the sport - the summer of 1977 through to 2010/10/26 05:49:12 UTC - you've never even expressed the least interest in ANYTHING along that line.
Nah, you totally nailed it in the early Eighties. You were never long about anything. If you had been the whole Ponzi scheme would've collapsed and revealed the physics professor to have been totally clueless.
I want to know without a doubt (1) when I am pushing too hard...
- Have you tried looking at your bar position, feeling bar pressure, seeing what was going on with the glider, checking horizon once in a while?
- Name one other individual in the world history of the sport who expressed who wanted or used a weak link to tell him when he was pushing too hard.
- And that's your Number One issue.
...and (2) what will break when I push too hard...
I dunno, let's look at some possibilities...
- towline
- weak link
- release mechanism
- flying wires
- harness
- some other component of the pilot-glider-tug system
I think I'll go with weak link. Bobby Fucking-Genius Bailey hadn't yet invented the tow mast breakaway, tow mast breakaway protector, bent pin barrel release.
...and (3) that no other damage need result because I push too hard.
Are you entirely sure about that? Have you gone up and deliberately pushed too hard and verified that no damage other damage has resulted? This guy:
pushed too hard and got his arm broken in three places. Good thing he wasn't using a Tad-O-Link. Would've undoubtedly gotten both arms broken in three places.
Furthermore, I will not use a mechanical weak link no matter how elaborate or expensive because there is always the possibility that it may fail to operate properly.
I've been wondering about this bullshit since I first read it. Nobody in the history of anything has ever used a "mechanical" weak link for anything.
1979/06
Dr. Lionel D. Hewett is a Professor at Texas A&I University, Kingsville, Texas, where he teaches physics, astronomy and solar energy and is doing research in solar air-conditioning. He has been sailing boats since he was 12 years old and now owns a 16 ft. sloop-rigged catamaran. Although he has been a licensed airplane pilot since 1966, it was not until the summer of 1977, while on vacation in California, that he made his first flight in a hang glider. He is currently a member of the USHGA and has been following the developments in hang gliding with considerable interest.
He's had some kind of contact with sailplanes. That's the Tost weak link system he's talking about and characterizing as "mechanical".
In skyting we use a simple and inexpensive strand of nylon fishing line which breaks at the desired tension limit.
- And how can one POSSIBLY go wrong in hang glider towing with simple and inexpensive.
- Who the fuck is "WE"? I'm not seeing a coauthor's name anywhere and if anybody else had a hand in any of this development then he should get his share of the credit. (This is sounding a lot like the Bob Kuczewski "we".)
There is no possible way for it to jam and fail to release when the maximum tension is exceeded.
Well that sure is a big plus over the Tost weak link. That complex mechanical shit jams and fails to release about every other tow.
Donnell doesn't have any money to spend on this shit and do things right. He can't do a powered winch or payout winch for proper tension control so he uses a long nylon towline tied to the trailer hitch to control tension just as well. This is a constant pattern throughout his career. Do things on the cheap, piss all over quality stuff, denigrate it for its complexity. Tost weak links will probably jam, get stronger, both.
Never gets anywhere near AT.
At the end he'll have a payout winch but no scooter, platform, dollies. Just foot launch on the pavement with a small one-size-fits-all trainer behind the truck with a simple, Reliable, easily reachable Linknife release. Twenty bucks and a string to tie it to your harness. You can get a dozen of them for the price of a Koch.
In my opinion, the LINKNIFE is exceptionally brilliant! It is the best release I know about.
Makes a point of never having heard of the Koch two stage so the Reliable Linknife is the best release he KNOWS ABOUT. So he sure as hell doesn't wanna look too hard at a Koch, Kaluzhin, or - God forbid - anything T** at K*** S****** has done 'cause then he'd know about and would hafta incorporate it. And that would force him to admit that his Skyting Criteria, Reliable Release, Infallible Weak Link hadn't been worth way less than shit when and since he first mailed them in to u$hPa in December of 1980.
Sure, it may get weaker through aging or wear and break too soon...
There's no thing as too soon. Too soon is just a synonym for too safe.
...but it cannot get stronger and fail to break.
It obviously did when you broke your arm. But that data wasn't compatible with Skyting Theory so you threw it out. And when it doesn't break when it's supposed to in reported incidents you conclude that it was accidentally doubled.
If it does break too soon, so what?
So nothing. It's a mere nuisance.
We simply replace it with a fresh one.
Which can't possibly break too soon 'cause it's fresh.
A properly designed weak link...
A properly designed SIMPLE weak link. Who the fuck ties a piece of fishing line in a loop and talks about it being properly DESIGNED?
...must be strong enough to permit a good rate of climb without breaking, and it must be weak enough to break before the glider gets out of control, stalls, or collapses.
Sounds a lot like Trisa and the Flight Park Mafia, don't it? Did they pick this up from Donnell? Or when adopting the Infallible Weak Link mindset does one just naturally fall into this kind of pattern of speech?
Since our glider flies level with a 50 pound pull, climbs at about 500 fpm with a 130 pound pull...
...never encounters thermal lift or turbulence....
...and retains sufficient control to prevent stalling if a weak link breaks at 200 pounds pull, we selected that value.
I developed just about all my own stuff independently with a lot of work, testing, tweaking. I'm proud of it and I don't use first person plural when I'm talking about it. You just pulled this stuff outta your ass, tied a knot in a piece of fishing line, assigned it supernatural intelligence, use "we" to imbue it with a fake aura of legitimacy to help sell it. Also 'cause you at least subconsciously sense that this is snake oil and are trying to relieve yourself of some of the liability.
Of course, a pilot could deliberately produce a stalled break at 200 lbs, just as he can stall a glider in free flight.
Also he could get gusted, hit a thermal or strong gradient, have his driver hit the gas and have a stalled break, get a line dig at 200 lbs and get a stalled break. But we're only gonna discuss glassy smooth air with everything going right and the pilot not pushing too hard.
But if he is trying to limit his climb rate...
- He's NOT trying to LIMIT his climb rate - you moron. He's trying to MAXIMIZE it. He's not up there for the thrill of seeing how low he can keep his glider before his driver runs outta runway. He's trying to get as high as possible in order to be able to hook a thermal and get the fuck outta there.
- Trying his best to limit his climb rate. And if that's not good enough... Hell he tried his best.
...and the forces exceed the break limit, the glider simply drops its nose to the free flight attitude and continues flying.
Or simply continues dropping its nose until he hits the runway or tumbles - depending upon initial altitude.
If the weak link breaks (or should the towline break) at less than the 200 pound value, the effect is even less dramatic and controlled flight is still present.
There's absolutely no possibility that you'll have just gotten airborne and will crash back onto the runway. We stringently and exhaustively tested every imaginable scenario and our safety margins were so ridiculously wide that we nearly died from boredom.
Most people are amazed at how small a string is needed for the weak link of a tow system.
Of "A" tow system or "OUR" tow system?
In fact, many people upon seeing it in operation for the first time...
We had six weaklink breaks in a row at Zapata this year. Russell Brown (tug pilot, tug owner, Quest Air owner) said go ahead and double up (four strands of Cortland Greenspot). He knows I used his Zapata weaklink in Big Spring (pilots were asked to tell the tug pilot if they were doing that).
And that’s 260 towline, Donnell. Thirty percent over your kite string.
...make a comment something like "Don't you need something a little stronger than that? It's going to break!"
I've heard it a million times before from comp pilots insisting on towing with even doubled up weaklinks (some want no weaklink). I tell them the same thing I'm telling you... suck it up. You're not the only one on the line. I didn't ask to be a test pilot. I can live with your inconvenience.
And that's constant forward pull, Donnell. So a lot fewer pounds per fpm.
But, of course, that's the whole point, it's supposed to break.
Ideally six times in a row in light morning conditions - at thirty bucks a pop before you start figuring in all the people in line.
And in order to break at about 200 lbs, it needs to be a single strand (loop) of No. 21 or 24 size nylon cord or a double strand (loop) of No. 12 or 15 size. For our glider we have found through trial and error...
TRAIL and error.
...that a loop of No. 18 braided nylon twine is ideal.
Perfection for any imaginable situation.
A single strand of this twine is rated at 140 lb breaking strength, so a double strength loop should break at 280 pounds. In practice, we...
...all four of us...
...have found that because of the knots, it actually breaks at about 200 lbs when tied in a loop and attached to the towline.
Can I use it? I fly at 320 and that'll let me be extra safe. And I can live with my inconvenience.
Although we suspect that the same weak link would work well with other gliders...
Other gliders than WHAT? Here's all we know about this glider - from earlier in this article:
By the way, in case you are thinking that 1/8 inch nylon cord with a rated breaking strength around 800 lb is too weak to use safely as a tow rope, then you should realize that skyting is never performed with a tow line tension greater than one "g". In other words, the tension is never allowed to exceed the total weight of the glider-pilot system, roughly about 200 pounds. As long as the tow line can withstand this force, it will never break. If it does break, it will do so at less than this force and no damage is done since the system is designed to recover from such a mild break.
So we know that your glider is roughly about 200 pounds 'cause you've determined that at roughly about one G it's impossible for nothing roughly unpleasant to happen when that roughly about 200 pounds of thrust instantaneously vanishes. It would be nice to know roughly how much of that roughly about 200 pounds is glider and roughly how much is pilot 'cause that's roughly a big fuckin' factor in glider control authority.
...we have not had the opportunity to run tests on other gliders to varify this suspicion.
- None of your twelve man research and test pilot team has?
- So you've just told us that all of us are flying the same unidentified glider and we're all clipping in at roughly the same weight.
- That's OK. Your unvarified suspicion on this issue is plenty good enough for me. Count me and my unidentifiable glider in.
Until such tests can be run, we strongly recommend that considerable caution be exercised in determining the correct weak link for any other glider.
Nah. Roughly 1.0 Gs in roughly glassy smooth air. What could be roughly more obvious and simpler.
One should start with a line that definitely breaks too soon...
Since we've now firmly established that...
Manned Kiting
The Basic Handbook of Tow Launched Hang Gliding
Daniel F. Poynter
1974
"A bad flyer won't hurt a pin man but a bad pin man can kill a flyer." - Bill Bennett
"The greatest dangers are a rope break or a premature release." - Richard Johnson
...there's actually no such thing as too soon. Only not soon enough can and will be a problem.
...gradually increasing the strength until a point is reached where the glider is able to climb at a good rate without breaking the weak link, but where no stall occurs when the weak link does break.
- Or until you run out of spare downtubes - whichever comes first.
- And be sure not to confuse a "recovery" with a "stall". A good rule of thumb is that when you slam in from roughly 1.0 Gs or under it was roughly a recovery. When you slam in from roughly over 1.0 Gs on a Tad-O-Link it was a stall. And you should immediately dial down half a G to get things well back into the recovery range.
- Note that if you experience a severe stall while testing at 0.8 Gs the problem was that you accidentally doubled your Infallible Weak Link and were actually doing 1.6. After your surgeon clears you to resume testing be extra careful not to double your Infallible Weak Link again.
Obviously, more work needs to be done in this area...
Don't worry, Donnell - and the rest of your research and development team. There's immediately gonna be a massive global universal testing program launched within the next half hour. It's gonna extend to paragliders when they erupt onto the scene and will continue on through at least at the first third of the second decade of the next century. Not one individual will ever get so much as a mildly skinned knee as a consequence of a Hewett Infallible Weak Link increase in the safety of the towing operation. Everyone mangled or totaled after such safety increasing inconveniences will have gotten so as a sole consequence of his shit towing and/or recovery skills. (Unless he was a popular Kool Kid in which case an invisible dust devil will be invented at some point in the following week.) And everyone mangled or totaled who'd foolishly gone up with a roughly 1.1 or over Tad-O-Link will have gotten so because it held fast too long in the lockout and didn't succeed soon enough in the whipstall.
...but even so, we have found our current system to be quite satisfactory and able to provide the necessary tension limiting and regulation needed for safe and enjoyable flight under tow.
There's no such thing as safe and enjoyable hang glider flight under tow. We are inherently and dangerously unstable under tow and we don't start breathing a little easier until after we've cleared the two hundred foot kill zone. And those of us still stupid enough to be flying Hewett Infallible Weak Links but smart enough to understand what can happen are scared shitless during that period. Doubly or more so when we've got some total douchebag driver like Billo or Jim Keen-Intellect Rooney poised to make good decisions in the interest of our safety. Then we've gotta pay real close attention to where the tug is and what it's doing for the next couple thousand feet 'cause things can get real ugly real fast if we don't - and frequently enough even when we do.
There is NOBODY who doesn't score a major feeling of relief after he tops out successfully and cuts loose to start hunting thermals. The only reasons you're enjoying safe and enjoyable flight under tow are 'cause you:
- don't have any other means of getting any airtime
- are flying only in glassy smooth morning and evening conditions
- have yet to rack up the twenty minutes of airtime you need to burn out on this boring shit
Our next article will discuss various methods of attaching the towline to the glider and why the skyting method is to be preferred.
See if you'll be able to spare a couple lines of print in which you can credit the individuals contributing to this historic revolutionary advancement.
Two possibilities... You're either:
- unthinkably selfishly hogging all the credit for a group effort
- lying to us in order to:
-- paint Skyting Theory as way more established than it actually is
-- be able to disperse responsibility if/when some of this dodgy bullshit blows up in your face - which it SHOULD have done
This guy's a definite prequel to Jim Keen-Intellect Rooney.
- fundamentally clueless and dishonest with himself and others
- incompetent
- uses first person plural all the fuckin' time to bolster his credibility when there's actually not one single other member of we
- every sentence so buried and enmeshed in huge mounds of shit that one doesn't even know where to begin
- zilch:
-- real world experience in real world towing on the glider end
-- known:
--- flying accomplishments
--- surviving student products
- ignores and/or pisses all over all legitimate and major engineering advancements
- will:
-- never have been wrong about anything until Lemmy Lopez / Zack Marzec blows up in his face
-- quietly slip off into permanent obscurity from the tiny little corner into which he's spent years/decades painting himself
-- be irrevocably erased from the history of the sport
He established an incredibly perfect habitat and breeding ground for every parasite and sleazebag imaginable to slip into the sport and dissolve it from the inside.
.
