From section 3.4 of the 1999 Hang Gliding Federation of Australia Towing Manual:
Recommended breaking load of a weak link is 1g. - i.e. the combined weight of pilot, harness and glider (dependent on pilot weight - usually approximately 90 to 100 kg for solo operations; or approximately 175 kg for tandem operations).
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.
The purpose of the weak link is to protect the pilot from lockouts.
All the flight parks that I am aware of are quite aware of this. They tell their pilots that the point of the weak link is save the glider from overload and that they should not rely on the weaklink to save them.
The purpose of the weak link is to protect the glider from overload.
You know, after all this discussion I'm now convinced that it is a very good idea to treat the weaklink as a release, that that is exactly what we do when we have a weaklink on one side of a pro tow bridle. That that is exactly what has happened to me in a number of situations and that the whole business about a weaklink only for the glider not breaking isn't really the case nor a good idea for hang gliding.
I'm happy to have a relatively weak weaklink, and have never had a serious problem with the Greenspot 130, just an inconvenience now and then.
I'm thinking about doing a bit more testing as there seemed to be some disagreement around here about what the average breaking strength of a loop of Greenspot (or orange) weaklink was.
The purpose of the weak link is to protect the pilot from lockouts.
Concussions are in fact very serious and have life long effects. The last time I was knocked out what in 9th grade football. I have felt the effects of that ever since. It changes your wiring.
All the flight parks that I am aware of are quite aware of this. They tell their pilots that the point of the weak link is save the glider from overload and that they should not rely on the weaklink to save them.
Here's the moronic foundation of the one G or less weak link "theory":
Donnell Hewett - 1981/10
A properly designed weak link 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. Since our glider flies level with a 50 pound pull, climbs at about 500 fpm with a 130 pound pull, and retains sufficient control to prevent stalling if a weak link breaks at 200 pounds pull, we selected that value.
That is ENTIRELY about lockout and stall prevention and has ABSOLUTELY NOTHING to do with overload protection.
Here's the off the scale moronic origin of the solo and tandem "standard aerotow weak links":
Quest Air
Aerotow FAQ
Equipment and Accessories
Weak Link
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.
That is ENTIRELY about lockout and stall prevention and has ABSOLUTELY NOTHING to do with overload protection. We now have solo and tandem gliders limited to 226 and 400 pounds towline respectively. AND...
USAFlytec - 2001/07/14
Steve Kroop - Russell Brown - Bob Lane - Jim Prahl - Campbell Bowen
The tail section of the Dragonfly is designed so that it can accept in-line as well as lateral loads. Furthermore the mast extension, which is part of the tow system, is designed to break away in the event of excessive in-line or lateral loads. The force required to cause a breakaway is roughly equivalent to the force required to break the double weaklink used on the tail bridle. More simply put, the mast would break away long before any structural damage to the aircraft would occur.
...we've got the damnable off the scale moronic tow mast breakaway which permanently maxes out Dragonfly tow capacity to 400 pounds.
That's why we use 3strand at the tug's end. Using 4 strand can rip things off (it's happened).
...figure that they need to dumb down their front end weak link to make it a tow mast breakaway protector - a weak link to protect a weak link. So now we've got something that occasionally blows...
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.
...before a solo "standard aerotow weak link".
But - even if we back the clock up to when Dragonfly culture was a little less stupid and using a double loop - the most tension a Sport 2 155 can get is 1.3 Gs - and then only if he doesn't mind violating FAA aerotow regulations and getting the rope half the time.
There is NO GLIDER that would have the slightest problem with 1.5 Gs or five hundred pounds towline - whichever is higher.
Thus ALL Dragonfly towing is using the weak link as lockout and stall rather than overload protection.
Just about all of us here in Houston use 600 pound weak links.
The purpose of the weak link is to prevent structural failure of the glider. A glider is not in danger of failing with a 600 pound weak link. The group here has been towing with these for decades and has never seen a structural failure.
I get pretty torqued up at the "strong weak link" advocates who come out of the woodwork when something like this happens and use it to say "see, this proves my/our point". This, in spite of not being there and only having second hand information to make this point. If you believe that fine, knock yourself out, but don't use BS like "this wouldn't have happened if only you had listened to me".
I have the greatest respect of Paul and Mark and their willingness to share what they know. I have zero respect for those who are using a tragedy to advocate a particular position, particularly when there is no proven link between their point and this accident.
Kinsley Sykes - 2013/02/11 17:46:12 UTC
Because this has been beaten to death - google Tad Eareckson and try to read the mind-numbing BS. Most of the folks who have been towing for decades have worked this stuff out.
The reason for the vehemence of the response is they pile on to any AT accident, with no knowledge of the cause, and trot out the, if only he had a strong weaklink, nothing would have happened.
It's fine to want to work on better solutions to make us all safer by improving technology, it's ugly and inhuman to use the death of a really nice guy to advance your point... in case it wasn't obvious I agree with Bart and Jim, and no it's not a lack of english comprehension - he said there would have been a different outcome with a stronger weaklink.
Kinsley Sykes - 2013/02/17 16:04:16 UTC
Deltaman and Zach seem to be jumping on Jim for not using facts.. while not using RELEVANT facts to make their case.. When these guys agree with themselves on a forum where they all talk to each other, (http://www.kitestrings.org/forum2.html) no big deal, but I worry that folks will read the lack of response as some sort of endorsement of these positions. Actually, if you are on the fence, but think maybe these "strong weaklink" guys have a point, please go to that forum and read through it. Then see if you want to trust your life to their theories..
I do think that doing things that question long held beliefs is good. People thought Galileo was a heretic and also were fond of the earth being flat. I am sure we can do things better in towing, just would like that to be fact based, not just conjecture.
I get pretty torqued up at the "strong weak link" advocates who come out of the woodwork when something like this happens and use it to say "see, this proves my/our point".
Ya know, Kinsley...
We had a very similar fatality involving a platform launch into a thermal blast - in this case a dust devil - and a glider involuntarily blown off tow at Hobbs on 1990/07/05. THIS:
Dave Broyles - 1990/11
I talked to a lot of pilots at Hobbs, and the consensus was that in the course of Eric Aasletten's accident, had a weak link break occurred instead of the manual or auto release that apparently did occur, the outcome would have been the same. Under the circumstances the one thing that would have given Eric a fighting chance to survive was to have remained on the towline.
The weak link breaking strength should be between 100% and 150% of the combined weight of the glider and pilot being towed...
was published in the magazine. And there wasn't ONE SINGLE WHISPER from anyone who was pretty torqued up at the "strong weak link" advocates who came out of the woodwork when that happened - for the second time in less than three months. Why do you think that is?
This, in spite of not being there and only having second hand information to make this point.
Paul wasn't "there".
Mark Frutiger had flown through the same air that became problematic for Zack a few seconds later. He observed him in the mirror throughout most of the critical period of the incident, felt the tension he was pulling and the Rooney Link pop, and landed while the thermal was still feeding.
He reports:
Mark Frutiger - 2013/02/08 19:12:21 UTC
Zack hit the lift a few seconds after I did. He was high and to the right of the tug and was out of my mirror when the weak ling broke. The load on the tug was not excessive as with a lockout, but I was not surprised when the weak link broke. I was still in the thermal when I caught sight of Zack again. I did not see the entry to the tumble, but I did see two revolutions of a forward tumble before kicking the tug around to land. 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.
Then five days after the crash - the same day Dr. Trisa Tilletti deleted all references to weak links and towing equipment from the USHGA aerotowing SOPs - Paul submits a report which states:
Apparently, Zach simply hit strong low level turbulence, probably a dust devil that could not be seen due to the lack of dust in Florida, the nose went too high and he tumbled at a very low altitude.
So now all the sudden we've got:
- strong low level turbulence
- probably a dust devil that could not be seen due to the lack of dust in Florida
- no mention of the Rooney Link blowing when the nose went too high
after Mark described only smooth, powerful, widespread thermal lift.
That doesn't even make it to the mark of speculation. That's just flat out lying.
Paul goes on to blow some more crap in our faces with with the following load:
Strong dust devils in Florida definitely do exist even though they are rare. My wife had a near miss when she encountered a severe dusty a couple years ago and I almost lost a brand new $18,000 ATOS VX when it was torn from its tie down and thrown upside down.
in a transparent and pathetic effort to get us to think that Zack really wasn't in trouble until the "severe dusty" tumbled him after the Rooney Link very clearly provided protection from a high angle of attack.
Then he finishes off by telling us...
I wish I could shed more light on this accident but I am afraid this is all we know and probably will know. Zach was a great guy with an incredible outlook and zest for life. He will be sorely missed.
...it's impossible to really understand this accident, hang gliding's dangerous, sometimes shit just happens.
So how come this "report" is being submitted by Paul...
This, in spite of not being there and only having second hand information to make this point.
...who wasn't there and had only having second hand information to make his points? You think maybe he got in touch with USHGA's attorney who advised that he, not Mark, submit the report to provide Mark with insulation from the false and misleading statements about turbulence and dust devils at the same time he was telling Trisa he needed to gut the SOPs?
I have the greatest respect of Paul and Mark and their willingness to share what they know.
Yeah, I'm sure you do. I'll bet Tim Herr, Dr. Trisa Tilletti, Mark G. Forbes, and the rest of the serial killers who control this sport do too.
I have zero respect for those who are using a tragedy to advocate a particular position, particularly when there is no proven link between their point and this accident.
So you're totally cool with the turbulence and dust devil - which Paul pulled out of his ass, probably with some help from Tim Herr - and totally hostile to any thought that the Rooney Link pop...
...which was present in Mark's original account and survived even in...
When the lift/turbulence was encountered, the weak link on the tow line broke as the nose of the glider pitched up quickly to a very high angle of attack. Apparently, the glider stalled or possibly did a short tail slide and then stalled and then nosed down and tumbled.
...Paul's self serving snow job played the slightest negative role in the course of events.
Most of the folks who have been towing for decades have worked this stuff out.
Yep. They never cease to tell us they have - especially the ones who only arrived on the scene a decade ago. But whenever one asks them:
- who worked it out
- how they worked it out
- what they:
-- worked it out to do
-- found didn't work out
we never seem to be able to get any straight answers.
The reason for the vehemence of the response is they pile on to any AT accident, with no knowledge of the cause, and trot out the, if only he had a strong weaklink, nothing would have happened.
- So what do Paul, Lauren, Davis, Rooney, Billo, Trisa do after any AT accident?
-- We have no agreement that a stronger weaklink would make it safer.
-- Please note that the weaklink *saved* her ass. She still piled into the earth despite the weaklink helping her... for the same reason it had to help... lack of towing ability.
-- Remember kids, always blame the equipment.
-- I wish I could shed more light on this accident but I am afraid this is all we know and probably will know. Zach was a great guy with an incredible outlook and zest for life. He will be sorely missed.
-- You're the one advocating change here, not me.
-- These are only questions if you're advocating change. Which I'm not. You are.
-- You're the one speculating on Zack's death... not me.
-- We probably never will know.
- So you're totally cool with the idea that once that cart started rolling Zack's death was inevitable. That if we had a magic wand and the ability to triple his Rooney Link strength and swap in a two point bridle the results would've been EXACTLY the same.
- And you're also totally cool with the idea that anybody we put on that cart when that thermal's about to break off will end up equally as dead.
It's fine to want to work on better solutions to make us all safer by improving technology...
As long as Rooney and his fellow Flight Park Mafia shits...
A few years ago, I started refusing to tow people with home made gear.
Approach it for what it is... completely untested and very experimental gear which will likely fail in new and unforseen ways as it tries it's damndest to kill you... and then we can talk.
Dr. Trisa Tilletti - 2012/06
What we have covered in this article is practical information and knowledge gleaned from the real world of aerotowing, developed over decades and hundreds of thousands of tows by experts in the field. This information has practical external validity. Hopefully, someone will develop methods and technology that work better than what we are using as standard practice today. Like the methods and technology used today, it is unlikely that the new technology will be dictated onto us as a de jure standard. Rather, to become a de facto standard, that new technology will need to be made available in the marketplace, proven in the real world, and then embraced by our sport.
...make sure none of it ever actually gets into the air.
...it's ugly and inhuman to use the death of a really nice guy to advance your point...
And it's beautiful and saintly to keep sending other really nice guys up in the exact same air in the exact same configuration that this really nice guy was flying in and using and expect different results - asshole.
...he said there would have been a different outcome with a stronger weaklink.
Yeah? Rooney's saying...
Jim Rooney - 2013/03/05 21:40:02 UTC
You want MORE.
I want you to have less.
This is the fundamental disagreement.
You're afraid of breaking off with a high AOA? Good... tow with a WEAKER weaklink... you won't be able to achieve a high AOA. Problem solved.
I'm sorry that you don't like that the tug pilot has the last word... but tough titties.
Don't like it?
Don't ask me to tow you.
Go troll somewhere else buddy.
I'm over this.
...there would have been a different outcome with a WEAKER weak link. But...
In the old threads there was a lot of info from a guy named Tad. Tad had a very strong opinion on weak link strength and it was a lot higher than most folks care for. I'd focus carefully on what folks who tow a lot have to say. Or Jim Rooney who is an excellent tug pilot. I tow with the "park provided" weak links. I think they are 130 pound Greenspot.
...I don't hear any of you motherfuckers:
- talking about how ugly and inhuman it is to use the death of a really nice guy to advance HIS point
- suddenly jumping on the New and Improved 100 pound Greenspot bandwagon
- talking about what a reckless asshole Davis is for using the new Morningside 200 pound accepted standard
...but I worry that folks will read the lack of response as some sort of endorsement of these positions.
Do you worry about the lack of response on The Davis Show after Davis pulls another one of THESE:
Okay, folks, this forum us beginning to turn into a cesspool.
Stop it now or I start kicking people out of here.
and locks down all the discussions?
Actually, if you are on the fence, but think maybe these "strong weaklink" guys have a point, please go to that forum and read through it. Then see if you want to trust your life to their theories..
How much worse could they end up than Zack Marzec who trusted his life to the "THEORIES"...
I do think that doing things that question long held beliefs is good.
- Obviously. And obvious that you yourself...
In the old threads there was a lot of info from a guy named Tad. Tad had a very strong opinion on weak link strength and it was a lot higher than most folks care for. I'd focus carefully on what folks who tow a lot have to say. Or Jim Rooney who is an excellent tug pilot. I tow with the "park provided" weak links. I think they are 130 pound Greenspot.
...are doing that constantly.
- Name another flavor of aviation in which equipment and procedures are based on long held BELIEFS.
- Lemme tell ya sumpin', motherfucker. ANYTHING you're doing in aviation that's based on ANYONE'S *BELIEFS* is - by definition - WRONG. And if you can't understand the arithmetic and logic which defines the THEORY by which we fly - or at least figure out who does and doesn't - it's a REAL bad idea for you to have hang gliding as a hobby.
People thought Galileo was a heretic...
He was. So are Mike Lake, Zack C, Deltaman, Ridgerodent, Swift, Freedomspyder, Yours Truly...
...and also were fond of the earth being flat.
It was pretty fuckin' flat where Zack Marzec impacted it.
I am sure we can do things better in towing...
Really?
- So...
Quest Air has been involved in perfecting aerotowing for nearly twenty years.
...is Paul:
-- lying
-- clueless
-- stupid
-- lazy
-- apathetic
-- all of the above
- How can we POSSIBLY do anything any better in towing when...
See, most people are happy with how we do things. This isn't an issue for them. They just come out and fly. Thing's aren't perfect, but that's life... and life ain't perfect. You do what you can with what you've got and you move on.
...aren't willing just to do what you can with what you've got and you move on?
It saddens me to know that the rantings of the fanatic fringe mask the few people who are actually working on things.
...that's gotten BETTER in the past twenty years.
...just would like that to be fact based, not just conjecture.
OH! That's what YOU would like? Well maybe you could explain some of the FACTS which were used as the basis...
Quest Air
Aerotow FAQ
Equipment and Accessories
Weak Link
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.
A year ago today, over seven months before Zack Marzec's 130 pound Rooney Link very clearly provided protection from a high angle of attack and tumbled him onto the runway from 150 feet, Dr. Trisa Tilletti published a brilliant fourteen page article on...
Dr. Trisa Tilletti - 2012/06
Some aerotowing operations--particularly ones with more powerful tugs like ours here at Cloud 9--have found that pre-tied weak links fail inconsistently and too frequently. Sometimes they perform well by breaking as expected under high loads, and not breaking inadvertently in mild turbulence, but sometimes they fail unexpectedly. This inconsistent weakness is likely caused by (a) the knot in the line that is used to pre-tie the weak link, (b) the garroting action of the lark's head knot, and (c) the ability of the weak link to loosen, shift, and wear. This is exacerbated by use of a Spectra bridle rather than a polypro bridle due to the smaller surface area of the Spectra bridle line and the inability of Spectra to absorb shock.
We and some other tow operators get significantly better results by using a Wrap-and-Tie (WT) weak link, made of the same 130 lb. green spot line. To make this kind of weak link, cut a 12-inch piece of line, thread it through the loop at the end of the V-bridle, wrap it around three to five times, and tie it with a simple overhand knot at the very end.
Then, add two more overhand knot ties, just inside the other ones. Pull the inner loop to use as your weak link, leaving the knots on the inside of the V-bridle loop, so that the knots are separated by the remaining loops as much as possible from the pulling force applied on the weak link in the middle. Here at Cloud 9, we prefer wrapping five times, so that the center loop is used for the weak link, and the knot is separated from the weak link loop by the two additional loops on each side of it.
The WT style of weak link performs very consistently, likely due to the extra weak link loops snugging down onto the bridle and not shifting around, and because the knot used to make it is separated far from the pulling pressures. Basically, it removes the knot from the actual weak link loop that is used, so it behaves much like a continuous loop of line without a knot in it.
... using Russell Brown's Wrap-and-Tie method - in conjunction with a polypro bridle - to get twice the strength out of a piece of 130 pound Greenspot that Zack Marzec was getting with his nasty Spectra bridle, which acts somewhat like an impact wrench on the weak link, and his shoddy Fisherman's Knot / Double Lark's Head Pre-Tied installation.
I get pretty torqued up at the "strong weak link" advocates who come out of the woodwork when something like this happens and use it to say "see, this proves my/our point".
Doesn't that make him a "strong weak link" advocate?
I mean, what's the difference between using 260 pound fishing line on a Spectra bridle installed with the Pre-Tied Method and 130 pound pound fishing line on a polypro bridle installed with the Wrap-and-Tie Method?
They both blow at 260 pounds direct, 520 pounds towline. That's very slightly over two Gs for Zack - which, as we all know, is twice what's a good rule of thumb.
Or is it OK to use 130 pound Greenspot no matter what we can jack the loop's breaking strength up to? If we could get a thousand pounds out of it would you be totally cool with it?
Kinsley Sykes - 2013/02/11 17:46:12 UTC
It's fine to want to work on better solutions to make us all safer by improving technology, it's ugly and inhuman to use the death of a really nice guy to advance your point... in case it wasn't obvious I agree with Bart and Jim, and no it's not a lack of english comprehension - he said there would have been a different outcome with a stronger weaklink.
Isn't Trisa...
The WT style of weak link performs very consistently, likely due to the extra weak link loops snugging down onto the bridle and not shifting around, and because the knot used to make it is separated far from the pulling pressures. Basically, it removes the knot from the actual weak link loop that is used, so it behaves much like a continuous loop of line without a knot in it.
...achieving a different outcome with a stronger weak link?
But I guess that's OK 'cause he's not using the death of a really nice guy to advance his point. He's been respectful and decent enough to not utter a single word on the incident.
Deltaman and Zach seem to be jumping on Jim for not using facts.. while not using RELEVANT facts to make their case..
Did you think Dr. Trisa Tilletti 1 and Dr. Trisa Tilletti 2 were using RELEVANT facts to make their case?
When these guys agree with themselves on a forum where they all talk to each other, (http://www.kitestrings.org/forum2.html) no big deal, but I worry that folks will read the lack of response as some sort of endorsement of these positions.
When those guys were agreeing with themselves in a committee they stack and in a magazine which they control and just talk to each other...
You are being much too complimentary IMHO. I got so nauseated reading it I had to take a breather. Do you mean to tell me they wrote an article that wasn't insipid and self-congratulatory to the extreme? I've found their entire series on aerotowing to come off rather poorly to say the least. A sad waste of such exalted and highly qualified medical professionals. How do I know this? Well they won't stop patting each other on the back about how great they both are. Pardon me while I puke.
...did you worry that folks would read the total absence of critical points of view as some sort of endorsement of their positions?
Actually, if you are on the fence, but think maybe these "strong weaklink" guys have a point, please go to that forum and read through it. Then see if you want to trust your life to their theories..
Did you read through that article and want to trust your life to their theories?
I know I sure didn't.
And I'll bet Zack Marzec didn't either. TWO Gs?!?!?!
That's exactly the problem.
People get themselves in the shit on the high tension side... a stronger weaklink gives you more tension... allows for stronger whipstalls/etc.
People that are in the shit are asking for stronger gear to get further into the shit?
I'm baffled.
Think how far into shit he could've gotten with TWO Gs! No telling how much stronger the whipstall, etc. could've been. No telling WHAT might've happened. He might've died when he hit the runway instead of in the ambulance on the way to the hospital. And none of us wants to see something like that happen.
HIGHER EDUCATION - 2012/06
TIE A (BETTER) WEAK LINK
You mean (STRONGER), right?
Many pilots don't really understand weak links. Simply, the ideal weak link used for aerotowing consists of a continuous loop of string or length of material, without a knot in it--especially not a frayed knot--because a knot weakens the string and weakens it inconsistently, resulting in inconsistent breaking strengths.
This entire article is obviously all about how to tie a STRONGER weak link - one that breaks more...
Some aerotowing operations--particularly ones with more powerful tugs like ours here at Cloud 9--have found that pre-tied weak links fail inconsistently and too frequently.
..."CONSISTENTLY".
So why is STRONGER "BETTER"? I've always heard that...
That's exactly the problem.
People get themselves in the shit on the high tension side... a stronger weaklink gives you more tension... allows for stronger whipstalls/etc.
People that are in the shit are asking for stronger gear to get further into the shit?
I'm baffled.
...WEAKER is BETTER. And I've heard that from some very highly qualified...
In the old threads there was a lot of info from a guy named Tad. Tad had a very strong opinion on weak link strength and it was a lot higher than most folks care for. I'd focus carefully on what folks who tow a lot have to say. Or Jim Rooney who is an excellent tug pilot. I tow with the "park provided" weak links. I think they are 130 pound Greenspot.
...professional tug pilots with some extremely keen intellects.
Many pilots don't really understand weak links.
Why not? I know a lot of flight park operators, tug pilots, and aerotow instructors and...
The normal braking force in pounds for a weak link is around 180, at least that is the regular weak link line used at most aerotow operations. By adding a second weak link to your bridal you are cutting the load on each link by half, meaning that the weak link will not break at the intended 180 pounds but it will need about 360.
If that is what you use and is what your instructor approved then I have no business on interfering, i dont know if you are using the same weak link material but there shoul be only ONE weak link on a tow bridle for it to be effective in breaking before higher loads are put into you and the glider should the glider gets to an attitude or off track so much that the safety fuse of the link is needed to break you free from the tug.
I made the same mistake on putting two weak links thinking that I was adding protection to my setup and I was corrected by two instructors on separate occacions at Quest Air and at the Florida RIdge.
...I find their expertise and ability to convey information totally astounding.
And what's so tough to understand about weak links anyway? Their purpose is to...
Btw, it's nothing to do with you "counting" on the weaklink breaking... Its about me not trusting you to hit the release.
If it were only about what you want, then you could use what you like.
You want the strongest weaklink you can have.
I want you to have the weakest one practical.. I don't care how much it inconveniences you.
I don't trust you as a rule. You Trust you , but I don't and shouldn't.
...the weaker they are the safer they are. What could be more simple than that?
Simply, the ideal weak link used for aerotowing consists of a continuous loop of string or length of material, without a knot in it--especially not a frayed knot--because a knot weakens the string and weakens it inconsistently, resulting in inconsistent breaking strengths.
Really?
- A lot of us have found that...
Zack C - 2013/03/12 01:12:26 UTC
The load tests that I've seen had one end of the weak link attached to a Spectra bridle (as in flight) and the other attached to a ring that allows the strands to be evenly loaded. In almost all cases, the weak link broke at one of the two places it exited the bridle. Weak links I've broken in flight have always broken at the bridle as well. The bridle attachment appears to be the weak point.
Tests were performed attaching the weak link to the bridle using single and double lark's heads in addition to the 'wrap and tie' method and no significant variance in breaking strength between these methods was found.
Testing weak links tied from "No 8" builders string line has shown that the type of knot used does not greatly affect the breaking strain of the weak link.
...knots aren't significant issues.
- Can you cite anything that supports your claim that knots weaken lines inconsistently? There's a lot of test data given by line manufacturers and in sailing textbooks on specific strength reduction percentages for specific knots.
- Can you explain why any specific knot should result in inconsistent break strengths?
- Since:
-- the one of the core issues of your article is to keep gliders within the FAA legal range
-- the FAA legal range is HUGE - 0.8 TO 2.0 Gs
-- the hook-in weight range for any given glider typically spans something in the neighborhood of a hundred pounds
-- blowing a weak link is never a big fucking deal - merely an inconvenience that increases the safety of the towing operation
why is the issue of consistency such a big fucking deal anyway?
The single loop of 130 pound Greenspot braided Dacron trolling line tied with a Fisherman's Knot installed on the end of a one or two point Spectra bridle with a Double Lark's Head became the standard aerotow weak link only after...
Based on several decades of experience and hundreds of thousands of tows conducted by numerous aerotow operators across the county, the de facto standard has become use of a 260 lb. weak link made as a loop of 130 lb. green spot IGFA Dacron braided fishing line attached to one end of the pilot's V-bridle. It is a de facto standard, because it works for most pilots and gliders and is usually near the USHPA recommendation of a nominal 1G weak link for most pilots.
...several decades of experience and hundreds of thousands of tows conducted by numerous aerotow operators across the county.
Doesn't making it better / more consistent / stronger by using the Wrap-and-Tie method and installing it on a polypro bridle - which...
Without shock absorption, a Spectra bridle acts somewhat like an impact wrench on the weak link.
...acts somewhat less like an impact wrench on the weak link - negate that track record and cast the role of the person using it as a...
Every now and then someone comes along with the "new" idea of a stronger weaklink. Eventually, they scare themselves with it and wind up back with one that has a very proven track record. I mean really... no exaggeration... hundreds of thousands of tows.
Say what you will, but if you want to argue with *that* much history, well, you better have one hell of an argument... which you don't.
It amuses me how many people want to be test pilots.
It amuses me even more that people...
A) Don't realize that "test pilot" is exactly what they're signing up for and B) actually testing something is a far more involved process than "I think I just try out my theory and see what happens".
Allow me to repeat... hundreds of thousands of tows.
Sure, there's other stuff out there too. Some of it even has a number of tows behind it... but hundreds of thousands is a very large number.
That's not "religion" my friend.
The shit works. It works in reality and it works consistently. It's not perfect, but Joe-Blow's pet theories have a very high bar to reach before they are given credence.
...TEST PILOT?
Shouldn't use of a Wrapped-and-Tied weak link on a polypro bridle with that short a track record be restricted to people who've...
Davis has been at an around all this plenty long enough to understand what's what and who's who.
...been at an around all this plenty long enough to understand what's what and who's who?
It is important to realize that, per FAA requirements, the weak link on the tug cannot be more than 25% stronger than the weak link used for the glider.
That's why we use 3strand at the tug's end. Using 4 strand can rip things off (it's happened).
...pretty well covered on that end.
- And I have no doubt whatsoever that you're swapping out your tug's weak link after tandem tows to limit things on that end to 282 pounds so you stay under 25 percent above a solo glider using a standard aerotow weak link on a two point bridle.
Historically, a 520 lb. double loop of 130 lb. green spot line has been the de facto standard for weak link used on the V-bridle for both the tandem and the tug.
Yeah. You're saying "historically" because you bloody well know that...
Something to bear in mind... the tug's weaklink is three strand.
For clarity... A normal single loop weaklink would be considered two. A tandem double loop is considered four.
In the tandem setup, the "weaklink" in the system is at the tug end, not the glider.
...about half a dozen years ago all the assholes operating Dragonflies swapped in three stranders to function as tow mast breakaway protectors and that all tandem flights are being conducted in flagrant violation of FAA aerotow...
HG Tandem Aerotow Operations
Date of Notice:
2006/03/15
Should the tandem glider become unattached from the tug during this maneuver, the nose high attitude of the tandem glider attained while doing this will cause a very abrupt stall which will result in a much greater altitude loss than one would expect (possibly more than 750 feet). The most extreme cases may result in structural failure of the glider.
It is CRITICAL to understand that the towed hang glider is at risk when the tow is slow and the glider is low. When towing a tandem glider, the tug pilot should fly the appropriate airspeed to keep the tandem glider in the proper position and if there is any doubt the tug pilot should fly slightly faster and avoid flying slightly slow. The tug pilot should avoid pulling up abruptly and leaving the tandem glider low. If the glider is low on tow, the tug pilot should attempt to speed up and to descend to the altitude of the towed glider, releasing the tow rope only as a last resort.
Flying with a tandem passenger is a special privilege which the FAA allows us to grant to qualified pilots. These pilots are supposed to be highly skilled. We expect tandem flights to be safer than solo flights, not more dangerous. Safety records do not currently seem to support this expectation. We expect tandem flights under the rules of the USHPA to be conducted in such a way that this expectation is realized.
David G. Broyles, Chairman of Safety and Training Committee
Steve Kroop, Chairman of Tow Committee
Paul Voight, Chairman of Tandem Committee
...safety regulations.
Technically, this can be legal if the V-bridle on the tug is longer and has a more acute angle than the V-bridle on the glider, which results in a vector angle that effectively makes the weak link on the tug act slightly stronger than the weak link on the glider.
But, technically, the tow mast breakaway is gonna snap about the time things get up to legal range for any glider using a double loop on a two point bridle and well before any glider using a double loop...
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).
...on a one point bridle. So what's the point of running this total charade of conducting aerotowing safely and legally? The FAA didn't do shit after Bill Bennett and Mike Del Signore and Arlan Birkett and Jeremiah Thompson were killed on tandem tows after front end weak link blows - so what are you worried about?
Pre-tied weak links made from 130 lb. green spot line work well for many aerotowing operations, are practical and appropriate for those operations, and thus this method has become a de facto standard.
Note how much more surface area is provided by the polypro bridle, so that pressure subjected to the weak link by the bridle is spread out over a much a larger area, and is thus reduced per unit area of the weak link which helps to reduce the chance of an inadvertent weak link break.
And thus increases the ratio of deliberate to inadvertent weak link breaks.
Some aerotowing operations--particularly ones with more powerful tugs like ours here at Cloud 9--have found that pre-tied weak links fail inconsistently and too frequently.
But I thought that...
Based on several decades of experience and hundreds of thousands of tows conducted by numerous aerotow operators across the county, the de facto standard has become use of a 260 lb. weak link made as a loop of 130 lb. green spot IGFA Dacron braided fishing line attached to one end of the pilot's V-bridle. It is a de facto standard, because it works for most pilots and gliders and is usually near the USHPA recommendation of a nominal 1G weak link for most pilots.
...the single loop of 130 pound Greenspot braided Dacron trolling line tied with a Fisherman's Knot installed on the end of a one or two point Spectra bridle with a Double Lark's Head became the standard aerotow weak link only after several decades of experience and hundreds of thousands of tows conducted by numerous aerotow operators across the county.
And...
Towing Aloft - 1998/01
Fortunately, we have good defenses against lockouts. These defenses include limiting the tow forces by using weak links and pressure gauges, proper distribution of the tow forces and proper training of pilots.
...limiting tow forces by using weak links is an important element in our defenses against lockouts.
914 Dragonfly tugs have been around since at least the late Nineties and have undoubtedly accounted for the vast majority of the experience and the hundreds of thousands of tows conducted by numerous aerotow operators across the county which has given us the Pre-Tied loop of 130 pound Greenspot as the standard aerotow weak link - endorsed by Wills Wing and mandatory at most flight parks and competitions.
So what you're saying is:
- The Pre-Tied loop of 130 pound Greenspot on the end of a one or two point bridle is the optimal standard aerotow weak link because it limits tow tension to a safe level.
- But if you increase the tow tension by using a more powerful tug and a higher tension / climb rate you can increase the strength of the weak link / allowable tow tension and maintain exactly the same level of lockout protection for the glider.
If you're surface static towing can you do the same thing? Use more horsepower to drive faster and up the weak link and maintain the same level of lockout protection?
You will only ever need full throttle for the first fifty feet of a tandem tow. Don't ever pull a solo at full throttle... they will not be able to climb with you. You can tow them at 28 mph and you'll still leave them in the dust... they just won't be able to climb with you... weaklinks will go left and right.
...throttle back on the tug instead of using a more dangerous weak link? That's what Rooney does and he's an excellent tug pilot...
The tow aircraft was a Moyes Dragonfly with a 914 Rotax engine and was piloted by a highly experienced tow pilot. The tow line was approximately 250 feet long which is standard and Zach was using the "pro tow" method where the tow line is attached directly to a bridle on the pilot's harness and is not attached to the glider at all. A standard 130 pound test weak link was being used.
...using a Pre-Tied standard aerotow weak link and...
You know, after all this discussion I'm now convinced that it is a very good idea to treat the weaklink as a release, that that is exactly what we do when we have a weaklink on one side of a pro tow bridle. That that is exactly what has happened to me in a number of situations and that the whole business about a weaklink only for the glider not breaking isn't really the case nor a good idea for hang gliding.
I'm happy to have a relatively weak weaklink, and have never had a serious problem with the Greenspot 130, just an inconvenience now and then.
I'm thinking about doing a bit more testing as there seemed to be some disagreement around here about what the average breaking strength of a loop of Greenspot (or orange) weaklink was.
...in fact.
Sometimes they perform well by breaking as expected under high loads, and not breaking inadvertently in mild turbulence, but sometimes failing unexpectedly.
When do you expect them to break? Have you ever heard the argument that...
Donnell Hewett - 1981/10
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"...
...weak links always break at the worst possible time, when the glider is climbing hard in a near stall situation?
At what point in Zack Marzec's flight would you have expected his Rooney Link to perform well by breaking under high loads?
This inconsistent weakness is likely caused by (a) the knot in the line that is used to pre-tie the weak link, (b) the garroting action of the lark's head knot, and (c) the ability of the weak link to loosen, shift, and wear. This is exacerbated by use of a Spectra bridle rather than a polypro bridle due to the smaller surface area of the Spectra bridle line and the inability of Spectra to absorb shock.
So have you measured the towline tensions at which these Rooney Links are performing well by breaking as expected under high loads, not breaking inadvertently in mild turbulence, and sometimes they fail unexpectedly? Or are you just blowing stuff out of your ass?
We and some other tow operators get significantly better results by using a Wrap-and-Tie (WT) weak link, made of the same 130 lb. green spot line.
Wouldn't those also be significantly worse results if you're in a lockout? Or is "better" just an automatic synonym for "stronger"?
I get tired as hell "refuting" all these mouth release and "strong link" arguments. Dig through the forums if you want that. I've been doing it for years but unfortunately the peddlers are religious in their beliefs so they find justification any way they can to "prove" their stuff. This is known as "Confirmation Bias"... seeking data to support your theory... it's back-asswards. Guess what? The shit doesn't work. If it did, we'd be using it everywhere. But it doesn't stand the test of reality.
...how come we're not using it everywhere?
Russell Brown, a founder of Quest Air in Florida and a well-known Dragonfly tug pilot, is also a sailplane pilot, tug pilot, and A&P mechanic for a large commercial sailplane towing operation in Florida. He told us that, like us, he has never seen a sailplane weak link break, either. Russell owned the first 914-powered Dragonfly ever made--he helped us build the second one, which we still fly. He is the one who, many years ago, showed us the method for making a WT weak link and suggested we use polypropylene rather than Spectra for hang glider V-bridles.
So how come Russell Brown:
- a founder of Quest Air in Florida
- a well-known Dragonfly tug pilot
- a sailplane pilot
- a tug pilot
- an A&P mechanic for a large commercial sailplane towing operation in Florida
- owner of the first 914-powered Dragonfly ever made
told everyone to just go ahead and double up the Rooney Links...
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).
...instead of having them use the much safer Wrapped-and-Tied weak links when they couldn't get any gliders airborne at Zapata a couple of years ago?
How come he didn't have Zack Marzec using a Wrapped-and-Tied weak link on a polypro bridle? I thought all those guys were super safety conscious and constantly working on perfecting aerotowing.
A pilot should not expect a weak link to break to prevent a lockout.
Really?
You're basing your endorsement of 130 pound Greenspot on...
Based on several decades of experience and hundreds of thousands of tows conducted by numerous aerotow operators across the county, the de facto standard has become use of a 260 lb. weak link made as a loop of 130 lb. green spot IGFA Dacron braided fishing line attached to one end of the pilot's V-bridle.
...the experience and the hundreds of thousands of tows conducted by numerous aerotow operators across the county. And damn near all of those numerous aerotow operators across the county are having all of their students and patrons use the Rooney Link...
The safety weak link is a very important part of the system. Its purpose is to disconnect the hang glider from the tug at any time the tow forces rise above a certain level. There's one at the hang glider end of the rope, and another slightly stronger one at the other end, on the tug. A pilot experiencing a challenging flight, as a result of inexperience or turbulence, will likely break a weak link before the tow is complete. This "accidental" release often prevents a rough ride from developing into a dangerous one, and the glider returns to the launch area and lands.
...as a lockout preventer. So are you just crediting these highly qualified professionals when you want to use them to back a convenient position and saying they're all full of shit when you want to make a conflicting point? Pick one, dude.
Sometimes the pressures produced at the start of a lockout are high, and the weak link may break early.
So if the Rooney Link is good for 226 pounds of towline PRESSURE and that pressure is reached at the start of the lockout the Rooney Link may break at the start of the lockout.
Sometimes the pressures are not very high at the start of the lockout and don't get high until the lockout progresses much further--in that case the weak link will break later.
And if towline PRESSURE is less than 226 pounds at the start of the lockout and doesn't reach 226 pounds until the lockout progresses much further the Rooney Link may break when the lockout progresses much further.
Is this gonna be on the final?
In either case, the primary purpose of the weak link is to protect the structure and equipment of the glider and tug by separating them--it is not to prevent a lockout.
But...
We want our weak links to break as early as possible in lockout situations, but be strong and reliable enough to avoid frequent weak link breaks from turbulence. It is the same expectation of performance that we have for the weak links we use for towing sailplanes.
We should still gear them to be on the ragged edge of sustainable tow and at or below the FAA legal range so we can use them to prevent lockouts.
Practically, some hang glider aerotow operators may want to use weak links that are at the low end of the legal range, let's say with an actual breaking strength between 80% and 100% of the MCOW of the glider. In this case, they may experience more unintentional breaks, but breaks will occur with less stress applied to the structure of the tow plane or glider.
Let's see if we can do the math on this...
A certified glider can pull six Gs while sustaining zero stress damage:
6x0=0
A two G weak link limits the glider to three Gs of stress damage:
3x0=0
That's only half the stress damage sustained at six Gs:
3x0=6x0/2=0
A one G weak link limits the glider to two Gs of stress damage:
2x0=0
That's only two thirds the stress damage sustained at three Gs and one third the stress damage sustained at six Gs:
2x0=0=3x0x2/3=6x0/3=0
That's exactly the problem.
People get themselves in the shit on the high tension side... a stronger weaklink gives you more tension... allows for stronger whipstalls/etc.
People that are in the shit are asking for stronger gear to get further into the shit?
I'm baffled.
...get himself in the shit on the high tension side further than this:
Either case is legal if within FAA limits, and can be ethical and practical if it works effectively and safely for that operation.
So the Rooney Link that dumped Zack Marzec into a tailslide and fatal whipstall might not be ethical and practical at Quest but just a bit down the road at Wallaby it could be counted on to break if you fail to maintain the correct tow position (centered, with the wheels of the tug on the horizon) before you can get into too much trouble.
I'm beginning to see why many pilots don't really understand weak links. Things get extremely complicated when you start looking at site specific issues of legality, ethics, practicality, and safety.
The strength of the weak link that is appropriate for a particular operation can depend on the power of the tug and resultant climb rate and climb angle of the tow.
And then there's the power of the tug and resultant climb rate and climb angle of the tow to consider. This is just spiraling out range of my comprehension capabilities.
To be legal, a hang glider pilot should not just use any strength weak link they want to use, it must be within legal limits, and coordinated with the weak link used at the tug end of the rope.
Unless:
- you have a tug driver who tells you to go fuck yourself...
Jim Rooney - 2013/03/04 19:31:36 UTC
I still won't tow people with doubled up weaklinks. You don't get to "make shit up". I don't "make shit up" for that matter either.
We all play by the same rules, or we don't play.
...if you're not happy with the Rooney Link that drops you off the bottom of the legal range or you're flying a tandem with a double loop of 130.
We have very powerful tugs here at Cloud 9 with very large and efficient Prince P-tip propellers. The diameter of the propellers we use on our Rotax 914 engines is the same diameter as the propellers we have on our Skymaster 225 hp engines--in fact, because of the P-tip, the effective diameter is increased by 6 inches, to 84 inches, which is 7 feet. The climb rate we get is amazing. Weather permitting, we tow on a daily basis here through most of the flying season, but we only see a few weak link breaks here each season.
- So you're towing at higher tension and using stronger weak links and only breaking a few each season?
- Doesn't that mean that you're using weak links which won't break as early as possible in lockout situations? Sounds to me like you're PROUD of that record - that you're only concerned about about them being be strong and reliable enough to avoid frequent breaks from turbulence and totally ignoring the other side of the equation.
- How many:
-- lockouts do you see:
--- there each season?
--- that happen low enough to matter?
--- at low level and are successfully defused by weak links?
--- at altitude which would've been successfully defused by weak links at thirty feet?
-- weak link pops do you see which:
--- save a plane from being overloaded?
--- increase the safety of your towing operation?
--- are necessary to increase the safety of the tow?
-- stalls following weak link pops do you see:
--- at altitude which would've been real ugly shortly after coming off the cart?
--- would've killed someone if several things had lined up just right?
Most of our solo pilots here at Cloud 9 use the 130 lb. line, so that they are towing with a 260 lb. nominal 1G WT weak link on a polypro V-bridle, which equates to using an actual 1.7G weak link on the towline.
Of course you are. And if they blow at just half that on people's test rigs it's because, as you and I both know with our backgrounds in formal research, that lab tests may produce results with good internal validity, but are often weak in regard to external validity--meaning lab conditions cannot completely include all the factors and variability that exist in the big, real world.
The worst performance...
What's that? Not breaking as early as possible in lockout situations or not being strong and reliable enough to avoid frequent weak link breaks from turbulence? Or both?
...comes from a relatively short Spectra or thin pro-tow bridle, especially when the weak link is attached directly onto the thin curved pin of the secondary release, which imparts high loads over a very small area of the weak link.
So if it breaks under light towline tension that's bad performance.
The best performance comes from three-point bridle using an appropriately long primary V-bridle made from 1/4" or 5/16" diameter polypro. The overall length of a three-point bridle system is much longer than that of a short pro-tow bridle, and thus will have more stretch and shock absorbing quality. Here at Cloud 9, we experience the most reliable weak link performance by using WT style weak links and three-point polypro primary and secondary bridles.
And if it doesn't break as early as possible in lockout situations that's good performance. And when it holds even better when subjected to increased loading over half towline as a consequence of the two point bridle apex angle - which is the precise opposite of what you'd expect and what physics predicts - that's FANTASTIC performance!
The use of a Spectra bridle is an accepted de facto standard, and works well for many towing operations. It just does not work well for our towing operation here at Cloud 9.
Why do you think that is? Earth's magnetic field, Coriolis effect, ozone hole, agricultural pesticides?
We used to see more weak link breaks happen here at Cloud 9 in the past, when more visiting pilots flying here were using pre-tied weak links and Spectra bridles.
Were those bad weak link breaks in turbulence or good weak link breaks as early as possible in lockout situations? Or were they a combination of the two such that the good and bad canceled each other out?
If they were bad weak link breaks why didn't you just insist on Wrapped-and-Tied weak links and poly bridles?
Because Spectra is slippery, we also used to see their bridles sometimes slip apart on tow. Some bridle makers are sewing their Spectra bridles now. We just have not had a problem with our polypro bridles slipping apart.
Sounds like the people who have their Spectra bridles slipping apart have much better lockout protection and shock absorption than the people whose bridles are holding together. Maybe you and the other people making bridles which hold together should be copying the designs of some of these other bridles.
TRACY: There are other factors that affect weak link performance. Faster tows create more drag, which increases load on the weak link, and makes the turbulence impart a sharper impact load on the weak link.
So does a 260 pound weak link blow at 200 pounds if the loading is sharp?
Higher climb rates and climb angles impart more load on the weak link...
So I guess you'd want a BETTER weak link for that.
...as does towing in a position that is too high or low, or too far to the side, rather than in the center of the cone of safety.
Well you should probably teach your students during tandem training not to tow in a position that is too high or low, or too far to the side, rather than in the center of the cone of safety. I had to start off solo and it took a really long time for me to learn that on my own.
Towing without a fin decreases directional stability and smoothness of the tow, which increases load and wear on the weak link.
A 260 pound weak link probably has a safe working load of 130 pounds - meaning that it won't degrade any more than the bridle will for towline tensions of 452 pounds two point or 520 pounds one point towline tension. Are you generating those kinds of tensions behind the Dragonfly on solos? Around four times normal tow tension? Or is it possible that your Wrapped-and-Tied weak links are only good for half of what you think they are?
Likewise, pro-towing decreases smoothness and the ability to control the tow and can increase loads on the weak link, as described earlier.
- So are your pro toads typically all over the sky? If they are why aren't you insisting they fly two point and why aren't they more than willing to comply?
- And and how come you're not saying anything about the fact that a one point weak link only sees 87 percent of the tension a two pointer feels?
These factors lead to a relatively high frequency of weak link breaks at aerotow hang gliding competitions.
I am more than happy to have a stronger weaklink and often fly with the string used for weaklinks used at Wallaby Ranch for tandem flights (orange string - 200 lbs). We used these with Russell Brown's (tug owner and pilot) approval at Zapata after we kept breaking weaklink in light conditions in morning flights.
Right.
An inadvertent weak link break places a pilot at a competitive disadvantage...
But that's just a CONVENIENCE issue.
...and can increase the chance of personal injury or damage to their glider--which is also a competitive disadvantage.
Nonsense.
It's completely about convenience.
People like to argue about it and in their arguments, they dig up rationalizations of it not being about convenience, but sorry... it very much is about convenience.
Take if from the other angle... if it were about safety... if you are truly concerned about your safety... why are you towing? Why are the people that are arguing about weaklinks towing?
The answer of course is that it's not actually about "safety".
People get pissed off not because the weaklink breaking made their lives scary... it made it a pain in the ass. They missed the thermal. They had to relight. Etc.
I'm not saying that these are invalid feelings.
I'm saying that they're not about safety.
Losing the line is the same as losing power. Loss of power does not cause stalls. That domain is strictly AOA.
When suffering a loss of power, if you do nothing, your AOA will change... but you have caused the stall, even if quite simply by your inaction, not the loss of power.
To be safer and tow more smoothly...
What part of:
IT'S NOT ABOUT SAFETY!
are you having so much trouble understanding? If this were really about SAFETY wouldn't everybody be flying weak links around the top of the legal range rather than right at or off the bottom edge?
...a comp pilot could use a small fin [ref 17] on his/her glider and use a three-point V-bridle instead of a pro-tow V-bridle.
...shouldn't there be a USHGA Special Skill signoff requiring the pilot to demonstrate that he can fly just as safely one point as two?
I mean, we've got a 360 degree turn signoff that people can get at five hundred feet and I've never heard about anybody getting creamed doing that. A pro toad has to start off at ground level and you JUST SAID...
...pro-towing decreases smoothness and the ability to control the tow...
...PRO-TOWING *DECREASES* SMOOTHNESS AND THE ABILITY TO CONTROL THE TOW. So why do we just allow anyone who feels like it to declare himself a pro with no qualifications whatsoever?
If they want to stick with a pro-tow bridle, they could reduce the likelihood of an inadvertent weak link break by: (a) using a polypro rather than Spectra bridle, to reduce the intensity of the shock load placed on the weak link; (b) making their bridle a bit longer so that the force vector on the weak link has the effect of making the weak link stronger; (c) using a slightly stronger weak link, such as 160 lb. rather than 130 lb. line--but only if that stronger weak link is coordinated with the weak link used by the tug; and/or (d) using a WT-style weak link rather than a pre-tied weak link, so that it will more consistently break at its intended strength.
Wait a minute...
Pro-towing DECREASES smoothness and the ability to control the tow and you want to do everything possible to PREVENT the weak link from breaking?!?!?!
This is SHEER MADNESS!!!
A weak link...
Towing Aloft [ref 4] - 1998/01
A weak link is the focal point of a safe towing system.
...is the focal point of a safe towing system and...
The "purpose" of a weaklink is to increase the safety of the towing operation. PERIOD.
...its purpose is to increase the safety of the towing operation - PERIOD.
How's it gonna increase the safety of the towing operation if you do all those things to keep it from breaking in the configuration, time, and place when you most need it to?
Again it seems to me that...
We want our weak links to break as early as possible in lockout situations, but be strong and reliable enough to avoid frequent weak link breaks from turbulence.
...you just want your weak links to be strong and reliable enough to avoid frequent breaks from turbulence and are totally forgetting about having them break as early as possible in lockout situations.
Finally, everyone should know that thorough aerotow training and currency results in a more proficient aerotow pilot who can tow more smoothly and can stay more precisely in the center of the cone of safety. When hang glider pilots can fly their gliders on tow as smoothly as a sailplane flies on tow, it is less likely that they will experience an inadvertent weak link break.
Such a shame that Zack Marzec apparently never read this article and thus didn't get the motivation he needed to pursue the thorough aerotow training and maintain the currency he needed to become a more proficient aerotow pilot who could tow more smoothly and stay more precisely in the center of the Cone of Safety.
What we have covered in this article is practical information and knowledge gleaned from the real world of aerotowing, developed over decades and hundreds of thousands of tows by experts in the field. This information has practical external validity. Hopefully, someone will develop methods and technology that work better than what we are using as standard practice today. Like the methods and technology used today, it is unlikely that the new technology will be dictated onto us as a de jure standard.
That's OK, motherfucker. Gravity's always gonna be around to dictate and enforce standards and procedures.
Rather, to become a de facto standard, that new technology will need to be made available in the marketplace, proven in the real world, and then embraced by our sport.
Sounds like Morningside has made a significant step towards embracing some of the technology I started advocating half a dozen years ago. Any thoughts on that?
This article was peer-reviewed and approved for publication by the USHPA Towing Committee.
I'm not one of your goddam peers - thank gawd - but it'll be a cold day in hell before I stop having fun reviewing it. Bummer for you, Tim Herr, and USHGA that it can't be recalled, locked down, or deleted.
Take look at the June issue of the USHPA magazine. You'll find thirteen poorly written and confusing pages of weak link mumbo jumbo written by Drs. Lisa Colletti and Tracy Tillman.
Also included in the article- five photos, four bar graphs and eighteen references.
I suspect the article is an attempt to provide flight park operators and USHPA with justification and ammunition in a legal case filed against them.
Do a mental substitute of "parachute" for "weak link".
Parachutes DO occasionally save lives - blown aerobatics, tumbles, midairs, sidewire failures, tow disasters, at least one unhooked launch... We have documentation and/or films, photos, videos on everything.
When REAL people push REAL safety issues - parachutes, releases, wires, wheels, preflights, hook-in checks, launches, approaches, weather - they ALWAYS cite ACTUAL INCIDENTS.
But when a scammer like Pagen is selling the party line on weak links, THIS CRAP:
Towing Aloft - 1998/01
Three recent aerotowing accidents have occurred--one fatal. The common thread in all three was a lockout and the use of a much too heavy weak link. Tandem gliders are much less responsive than smaller gliders and the pilot in command often has a less than ideal position on the control bar. The situation shouldn't be compromised by an over-strength weak link.
is the best he can do in over 350 pages worth of opportunity.
From Lauren Eminently-Qualified-Tandem-Pilot Tjaden this:
I rarely break weak links -- in fact, I believe the last one was some two years ago, and I have never broken one on a tandem (probably because I am light and also because I change them whenever they show any signs of wear). They are a good thing to have, though!!
Am I "certain" about anything?
Nope.
However, some things get real obvious when you're doing them all the time. One is that weaklinks do in fact save people's asses.
Jim Rooney - 2011/08/31 09:25:57 UTC
Oh how many times I have to hear this stuff.
I've had these exact same arguments for years and years and years.
Nothing about them changes except the new faces spouting them.
It's the same as arguing with the rookie suffering from intermediate syndrome.
They've already made up their mind and only hear that which supports their opinion.
Only later, when we're visiting them in the hospital can they begin to hear what we've told them all along.
Note that in the fourteen pages of rot constituting Trisa's article - with the entire history of aerotowing to draw on - there isn't the slightest pretense of an attempt to link a higher rating weak link to either a glider overload resulting in so much as a slightly elongated bolt hole or lockout resulting in so much as a slightly bowed downtube.
- It's awfully difficult to cite incidents to illustrate your points when they simply don't exist.
- The good news is that it's extremely easy to totally disregard all the lockouts, stalls, broken downtubes, broken arms, and dead bodies that make total hash of your points.
I think what you're picking up on is my lack of willingness to discuss this with people that have already made up their minds.
Sorry for that, but it's just the nature of the beast.
I have no issue with discussing this with people that don't have an agenda.
I get very short with people that do however.
Am I "certain" about anything?
Nope.
However, some things get real obvious when you're doing them all the time. One is that weaklinks do in fact save people's asses.
You're 100% onto it... relying on the skill of the pilot is a numbers game that you'll lose at some point.
I find that so many people do not appreciate how fast and furious lockouts can happen.
They're exponential in nature.
Twice the time doesn't equate to twice the "bad"... it's four times the "bad"... then 16... it gets dramatic fast.
Is a weaklink going to save your ass? Who knows? But it's nice to stack the deck in your favour.
Now flip the argument and you start to see the devil.
A glider can take a whole shitload more force than a weaklink can.
So, if you're of the "sole purpose" cult, then you see no issue with a LOT stronger weaklink.
Well, it won't take long with that system before we've got a lot more dead pilots out there.
So they can stuff their philosophical purity bs... cuz I have no desire to tow someone to their death, no matter how willing they may be.
I'm not playing with this stuff in my head and just dismissing it. There's been a lot that's gone into this system.
I've seen too many people walk the "strong link" road only to find out the reality of things.
Fortunately, they've been unscathed, but there have been a lot of soiled underpants in the process.
I'm happy to discuss this stuff.
But I'm sick to death of arguing about it.
So what you're saying is that:
However, some things get real obvious when you're doing them all the time. One is that weaklinks do in fact save people's asses.
You're 100% onto it... relying on the skill of the pilot is a numbers game that you'll lose at some point.
- you're routinely seeing pilots who really don't have the proficiency to safely aerotow experiencing low level lockouts
- these people are coming out smelling like roses solely because they consistently luck out better than Mike Haas, Steve Elliot, Roy Messing, and Lois Preston did - that they owe their lives to a deck that is stacked in their favor...
Is a weaklink going to save your ass? Who knows? But it's nice to stack the deck in your favour.
...with a piece of fishing line
- all of us will one day inevitably find ourselves in a situation in which our lives are dependent upon our Rooney Links blowing at just the right time (just as all of us will one day inevitably find ourselves in a situation in which our lives are dependent upon...
In particular... Third Party Verification.
You won't save you, but your friends might.
Not always, but they're more reliable than you.
Why do you think that airline checklists (yes our lovely checklists) are check-verified by pilot AND copilot?
That's all I got for ya.
The other topics have been beat to death here.
If there was an answer, we'd all already be doing it.
...our friends noticing our dangling carabiners)
If a couple of people blew sidewires and were lucky enough to be altitudes to get the silk popped with ten or twenty feet to spare wouldn't those be:
- pretty much just matters of dumb luck?
- screaming for incident reports and an advisory?
- dice rolls the pilots wouldn't expect to get away with more than a couple of times?
- an issue:
-- to which responsible flight parks, clubs, and national organizations would direct a lot of energy in order to prevent recurrences?
-- which - if not safely addressable - would scare the crap out of any sane person and cause him to pursue another hobby?
- a call for suspect gliders to be immediately grounded until the problem could be properly resolved?
- incidents which would:
-- be reported by multiple witnesses and spark a lot of discussion on a lot of forums?
-- very likely be captured on two or more cameras?
- subjects for video postings which would immediately go viral?
Wouldn't a video of a muppet whose skills failed him to the extent that his life became dependent upon a deck stacked with a Rooney Link look a lot like THIS:
- There aren't a lot of videos around that look like this.
- This guy's skills didn't fail him. This guy was on a first ever aerotow and had no fuckin' clue what he was doing.
- His glider was crashed and substantially damaged and his nose was broken and he declared an immediate end to his twenty-one second aerotowing career.
- This video went viral and continues to be discussed regularly seven years after the event.
- No aerotower is watching this video and saying, "Wow. That could've been me! I'm only willing to subject myself to that level of risk because I always fly with a standard aerotow weak link and thus have the deck stacked in my favor."
How come you're perfectly willing to keep towing these bozos who lock out low and require well timed Rooney Link pops to keep them alive but you refuse to tow...
I'm not sure who you're arguing with Zack, but it's sure not me... cuz man... you've got some pretty big hangups mate.
You're hear to argue. Plain and simple. I've got better stuff to do.
Go blow smoke somewhere else. I couldn't give a rats ass... I won't be towing you so what do I care?
...Zack C? You say...
Jim Rooney - 2013/02/16 05:05:41 UTC
Here's a little bit of bitter reality that ya'll get to understand straight off. I won't be sugar coating it, sorry.
You see, I'm on the other end of that rope.
I want neither a dead pilot on my hands or one trying to kill me.
And yes. It is my call. PERIOD.
On tow, I am the PIC.
...you don't want a dead pilot on your hands and thus will almost always refuse to tow anyone with anything heavier than a Rooney Link.
Well, Mark Frutiger ended up with a dead pilot on his hands:
Zack Marzec pro toad with a Rooney Link and bent pin releases with barrel actuators out in front of his shoulders.
Isn't it possible that:
- having a release actuator that allows one to blow tow with both hands on the basetube
- towing two point such that a portion of the tow tension holds the nose down to proper trim
- using a 250 pound / 1.4 G weak link which is less likely to break at the worst possible time, when the glider is climbing hard in a near stall situation
...could, in some unlikely set of circumstances, help stack the deck in one's favor better than the Rooney Link would stack the deck in one's favor?
Or does the reason you're refusing to tow Zack have absolutely nothing to do with concern for his - or your - safety and everything to do with your fear and hatred of competent pilots who know what the fuck they're talking about and can and will expose you and your fellow cult leaders as the dangerous, incompetent, lying, sleazy frauds you are?
Prior to about 15:00 local time at Quest on 2013/02/02 - four months ago today - you could try to make an argument that Zack Marzec was a better, safer, more competent pilot than Zack C. You can't do that anymore. Zack Marzec now finishes a distant second to some tourist heading out to the dunes for his first and last hang gliding experience.
Three quarter or two G weak link or glider release - doesn't matter much.
If it's a three quarter G weak link you can't argue that it does anything to mitigate the severity of the lockout.
If it's a two G weak link you can't argue that it's endangering, or even annoying, the tug - which, we note, doesn't bother to fix whatever's going on back there by making a good decision in the interest of the glider's safety and giving it the rope.
If the tug is a Dragonfly we know that the tension never gets much over four hundred pounds - and is probably a lot less because, as noted above, he never bothers to fix whatever's going on back there.
Note that the glider's not being the least bit stressed out...
and his Rooney Link - which, you may recall, comes through that lockout ready for another one just like it.
Points...
- If you get to the point at which you're locked out enough for ANY weak link to kick in you better be reasonably high.
- It's total fuckin' lunacy to expect legal range weak link strength to be a consideration in lockout:
-- duration
-- severity
-- recovery altitude
and glider and tug control and safety.
Thanks again, God.
---
2022/04/05 14:00:00 UTC
The video is from the Mexican state of Jalisco - La Laguna Seca de San Marcos at around 20°18'01.62" N 103°33'05.80" W.
Mark Knight - 2013/06/04 18:00:44 UTC
SonoraWings.com
480-251-1515
A local Hang Glider Pilot / Machinist, is making some aluminum string batten tips for his U2. The Outer Batten Tips here is Arizona tend to wear off fairly fast due to the hard ruff ground.
He has a CNC lathe and decided he would make a few for his glider. I saw them and thought they would be nice on my school gliders that get dragged and beat to death by students during lessons.
A plastic one from Wills Wing cost .72 cents. I'm going to try them out on my school gliders. Is it worth it? Does anyone else want some while he has the machine setup making them? $7.50 each.
Let me know what you think.
Ya know what I think, Mark?
You fuckin' Dragonfly assholes have got a lot better things to worry about right now...
...than outer batten tips tending to wear off fairly fast due to the hard ruff ground.
But I guess if you were the least bit interested in CRITICAL issues you'd have actually participated in the discussions about your student Bryan Bowker, Zack Marzec, and Ben Dunn.
So this "Tiberiu" person registers on The Jack Show on 2013/04/18 - a month and a half after Zack Marzec is killed by his Rooney Link - and uses a photo of a Rooney Link:
as his avatar. And, of course, nobody says anything.
Somebody find me an avatar photo of a frayed sidewire.
---
Edit - 2013/06/15 14:12:58 UTC
Oops. Didn't recognize Tiberiu as an actual name. So not 'this "Tiberiu" person' - just Tiberiu. Sorry 'bout that.
