[TadEareckson]

Hi Joe,

Three months ago on The Davis Show you started the "No-knot weak links" thread:

http://ozreport.com/forum/viewtopic.php?p=101585

The third and fourth posts from it:

Ridgerodent - 2011/09/01

~18. Construction - Shear Links

#01. Objective

A properly constructed Shear Link will maintain its integrity to its breaking point, failing instantly and cleanly.

http://www.energykitesystems.net/Lift/h ... etraps.pdf

William Olive - 2011/09/01

Don't bother going there until you have used them.

This isn't a new idea. We used shear links in the past, and there's a reason we don't use them now.

String links work. String links fail safe (ie anything that degrades them makes them weaker).

For the purposes of that and several other discussions, Billo is an idiot.

Tost Flugzeuggeratebau

Weak links protect your aircraft against overloading.

01. The weak link has one purpose and one purpose only - and that's to keep your plane from being overloaded.

02. Largely thanks to Donnell Hewett, there are probably only about a dozen or so people in hang and para gliding who understand that.

03. If we used a single weak link which held to about five or six hundred pounds of towline tension on all solo and tandem hang and para glider flights we would have no weak link problems.

04. It ain't rocket science to put something between a glider and a towline that'll blow between five and six hundred pounds.

05. Tost weak links are metal strips with holes of varying diameters drilled through them to weaken them to the desired values.

06. We can use loops of various strength strings on towline or bridle ends.

07. "Shear Link" is a term I coined for a weak link I developed in 2006 based upon two elements stitched together. The number of stitches determines the strength and when that loading is reached the stitching fails and the elements shear apart.

08. I don't know what Billo is talking about when he references "shear links" and I'm fairly positive that he doesn't either. And he most assuredly did not bother to read the reference he told everybody else to not bother reading.

09. You learn NOTHING by "using" weak links. If it tests at five hundred pounds on the ground it'll blow at five hundred pounds in the air. If it tests at 0.8 Gs on the ground you'll be seeing a lot of crashed gliders. That ain't rocket science neither.

10. Hang glider aerotowing has NEVER employed anything but string and - in Europe - Tost sailplane weak links.

11. There has never been a instance of a certified hang glider suffering a negative consequence as a result of a heavy weak link because there has never been a certified hang glider broken under positive loading on tow.

12. Zillions of minor crashes, a good many serious injuries, and several fatalities are attributable to the use understrength weak links.

String links fail safe (ie anything that degrades them makes them weaker).

13. That statement is moronic. Start asking around and try to find people who really feel safe coming off a cart with a weak link just over normal tow tension.

Recommended: a robust study of what Tad generates. Reach for robust release information, test results, design implications.

Who's gonna do this? What's it supposed to determine? Outside of glider and parachute designs nobody studies ANYTHING in hang gliding. The total idiots running the flight parks have no clue as to what the stuff they're using now - double, triple, quadruple strand 130 pound Greenspot - blows at. They just do things 'cause that's the way they've always been done and aren't the least bit concerned that the first person to do it that way was also a total idiot. And if anybody actually studies anything he - at best - gets totally ignored while everybody goes on exactly as they have for the past twenty our thirty years.

We crash and kill people because we put release actuators on downtubes and shoulders, use weak links which blow at normal tow tensions, and teach people to perform preflight procedures which will allow them to assume they're hooked in at launch. We know that people who always opt for landing on their feet are about hundred times more likely to break downtubes and arms as people who land on their wheels. When has common sense - let alone robust study - ever put any discernible dents in hang gliding's biggest problems?

I studied the crap out of my Shear Link concept before putting it out for public consumption. I spent a good chunk of the winter of 2006-7 on the test rig blowing Shear Links in various configurations to document predictability, tolerances, range.

And where is hang gliding today after all that effort?

Matt Christensen - 2011/11/23
Vienna, Virginia

After surveying my options of places to train, I figured it would be fun to escape the rapidly cooling air of northern Virginia and do my AT training at Quest Air in Groveland, Florida.

Day Two

This day I did nine tows with four weak link breaks. The weak link breaks were all early on in the tow and all but one were in basically level flight. Either the weak link material that I was using was bad or the knots were compromising the strength, either way I got some good practice in dealing with breaks!

I feel very fortunate to have done my training at Blue Sky and now with Quest. If you have the opportunity to work with either of these operations, I highly recommend them both.

Singing the praises of the 130 pound Greenspot pin bending morons who perfected aerotowing twenty years ago and brutally suppress any and all attempts to interfere with this declared state of perfection.

We don't need any more study until we start getting the crap out of the air and replace it with the decent certified stuff we already have gathering cobwebs on the shelves. And in order to do that we need to start getting the crap experts and professionals out of positions of control.

[TadEareckson]

Nobody - 2011/11/24

http://www.dynamicflight.com.au/WeakLinks.html

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. Lockouts can and do occur without increasing tow tension up until the point where the glider is radically diverging from the direction of tow. At this point tension rises dramatically and something will give - preferably the weak link. Given that a certified glider will take 6-10G positive a 1.5G weak link as opposed to a standard 1G weak link should not significantly increase the risk of structural failure. It will however significantly decrease the probability of an unwanted weak link break.

Consider a standard tow force of up to 0.8G. A 1G weak link gives a 25% strength margin. A 1.5G weak link gives 88% strength margin or 300+% more than for the 1G link. At weak link break a 1G link will give a total glider load of 2G, a 1.5G weak link a total load of 2.5G or 25% more. The stronger weak link therefore gives a 300+% increase in strength margin for a 25% increase in ultimate load.

I use a stronger weak link for the simple reason that low level weak link breaks are dangerous as the glider may not recover from the probable ensuing stall prior to hitting the ground. They are also dangerous in tailwind launch conditions although you should never take of tailwind in anything stronger than you are willing to land in. In my opinion these problems presents a far bigger risk than that of structural failure. In my experience weak link breaks cause numerous problems, whereas thanks to the quality of today's gliders structural failure is almost unheard of. Yeah, I do know of on incident where a pilot locked out and was pulled through a previously straightened down tube leading to partial structural failure – the pilot was OK. In the event of a lock out I plan to release, and release early, because I know

that by the time my weak link breaks (no matter how weak) the glider is likely to be diverging from the tow direction in a steep bank and dive. If my release fails the weak link will still break before the glider. This being said it is still far preferable to use low tow tension, headwind launch, and a standard weak link.

1 The bridle set up is the pilots responsibility - after all they depend on it

2 The weak link forms an integral part of the bridle set up. It should be made and tested by the pilot. If the knot comes undone then the pilot should learn to tie a better one. The weak link will only break at a consistent load if the string snaps, not if the knot comes undone.

3 Higher climb rates and heavier glider/pilot combinations will inevitably need stronger weak links. One size weak link does does not fit all. A 1G weak link for a heavy pilot may well represent 1.5G for a light one. If they keep breaking make them stronger. Alternatively reduce tug climb rate to decrease tension or fly a lighter glider ;)

4 Experience has shown that different batches of weak link line from the same manufacturer break at quite different loads. Test each batch yourself using exactly the set up you use in the glider. Use your personally tested stuff exclusively.

5 The way the weak link is set up does influence its breaking load. The knot is the weakest point and decreases the strength of the line to ~50-70% of its un-knotted strength. Different types of knots weaken the line to different degrees. Because of this it is important to tie the same knot/s every time and position the knot/s consistently. If the knot is under tension a given number of strands of weak link will be weaker than if the knot is not under tension (i.e. excluded from the tension strands). It really doesn't matter what type of knot you tie (provided it doesn't come undone) or where you position it provided you are consistent and you test your system as in 4 above.

6 Have a bridle system that is as foolproof as possible. Remember nothing is absolutely foolproof because fools are just too damn ingenious. A system that only requires a snap hook to be attached to the tow line is almost foolproof. The pilot can then personally check his/her system during their preflight.

7 Make sure all your stuff is good stuff. Check you stuff works. Personally put your own stuff together. Check you have put all your stuff together right – remember glider, harness and tow bridle are all essential elements of your stuff.

8 Accept that tug pilots come in all flavours - the good, the bad and the ugly. So do tow pilots. Do your part right and make their job easy. If you feel they could give a better tow give them the feedback they need to do this. Diplomacy may be required. Remember hooking onto tow is an article of faith on both ends of the line.

9 None of this is rocket science. It is basic physics combined with elementary mechanics. It applies to all aerotowing and to towing in general. If things go wrong analyse why and fix the problem. Develop the most foolproof system possible. Do it the same way all the time, every time. Remember Murphy's extended law which states: "If anything can go wrong it will go wrong. It will also be the worst possible thing that could go wrong and will inevitably occur at the worst possible moment". Also remember Sod's law which simply states: "Murphy was an optimist"

10 Follow 1-9 then relax and enjoy stress reduced towing.

bobk

Another excellent article!!!

If Tad wrote like that (and maybe he has at other times and places) then we'd be getting along splendidly. Sure, there may have been a few typos, but there was no foul language, there was no wishing anyone else dead, there was no attempt to humiliate anyone. It was just clear and straight information. This is exactly the kind of thing I'd like to see on US Hawks!!!

Thanks Nobody!!

Jim Rooney - 2011/08/28

Yeah, I've read that drivel before.
It's a load of shitt.

Davis Straub - 2008/04/23

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.

Jim Rooney - 2007/07/22

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.

Jim Rooney - 2008/11/24

I've personally refused to tow a flight park owner over this very issue. I didn't want to clash, but I wasn't towing him. Yup, he wanted to tow with a doubled up weaklink. He eventually towed (behind me) with a single and sorry to disappoint any drama mongers, we're still friends. And lone gun crazy Rooney? Ten other tow pilots turned him down that day for the same reason.

Davis Straub - 2011/08/26

We had six weaklink breaks in a row at Zapata this year.

http://www.youtube.com/watch?v=bTa6XL16i0U

[TadEareckson]

Bob says it's an excellent article!!!

Rooney says it's drivel and a load of shitt.

Straub and Rooney - neither of whom would know what Gs were if they were branded on their cheeks and foreheads backwards so they could read them in the mirror - say that it makes no difference whatsoever what Bob thinks. He's got three choices:

1. Use a Dynamic Flight weak link capable of safely getting him off the ground and to altitude in soaring conditions and keep going to the back of the back of the line when they catch him with it.

2. Use a Straub/Rooney Link...

http://www.youtube.com/watch?v=JR_4jKLqrus

...and keep going to the front of the line as long as he keeps surviving the stalls and crashes.

Ridgerodent - 2011/08/31

Zack figured it out. Well done Zack! Enjoy your vacation.

Kinsley Sykes

Well actually he didn't. But if you don't want to listen to the folks that actually know what they are talking about, go ahead.

Feel free to go the the tow park that Tad runs...

3. Go to go the the tow park that Tad runs because if he goes to the tow parks run by Malcolm, Paul and Lauren, James, Matt, John, Steve, Adam, Tracy, or Bart he's back at Options 1 and 2.

[TadEareckson]

bobk - 2011/11/24

Another excellent article!!!

That was the article that I read and kept thinking about for a couple of years 'cause it so conflicted with all the programming I had gotten from idiot hang gliding culture for couple of previous decades. But I FINALLY GOT IT. I was FINALLY able to fully understand that the weak link had ABSOLUTELY NOTHING to do with lockout protection and that:

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.

And here's Zack going through the accelerated/push version of what I had to do on my own:

2010/11/07

Do you realize how difficult what you're asking me to do is? You're asking me, a not particularly experienced H3, to discard most of what I've been taught about weak links and the convention that has been accepted at pretty much all aerotow flight parks and competitions and trade it for a practice that very few are endorsing. It's very hard for me to believe that the convention is the convention only because everyone following it is an idiot. I'm going to try to get the other side of the story from those who advocate the 130 lb loops. Everyone here seems to use them only because they've been told to (myself included).

And here's Zack emerging from the dark dank tunnel of Straub/Rooney level superstition, ignorance, stupidity, and deceit a little over a month later:

2010/12/09

I think you've got me checkmated. No matter what I say you have a response and at this point I've got nothing left...I have no choice but to accept your position. I've seen so much fallacy from the people that push the universal 130 lb loop that I no longer doubt there isn't a good reason we use them. My hope for weaker links was aborting lockouts in the event of a release failure, but my thinking now is that if a lockout occurs low enough to end in a ground impact, it's likely this will occur before tension increases enough to break a 130 lb loop, and 130 lb loops are at risk of breaking at dangerous times. So yeah, having a better release is a much better idea.

If Tad wrote like that (and maybe he has at other times and places) then we'd be getting along splendidly.

bobk - 2011/10/23

As for Nobody's request for me to read a document, I haven't found the time yet. I'm sorry, but I don't have time to read everything that everyone asks me to read.

So what's gonna start happening to get the problem fixed now that you've read DYNAMIC FLIGHT's article?

Jim Rooney - 2011/08/28

Yeah, I've read that drivel before.
It's a load of shitt.

It's been around, I believe, for about a dozen years and...

Matt Christensen - 2011/11/23

This day I did nine tows with four weak link breaks. The weak link breaks were all early on in the tow and all but one were in basically level flight. Either the weak link material that I was using was bad or the knots were compromising the strength, either way I got some good practice in dealing with breaks!

I feel very fortunate to have done my training at Blue Sky and now with Quest. If you have the opportunity to work with either of these operations, I highly recommend them both.

...hang gliding is still the biggest idiot sanctuary on the face of the planet.

Sure, there may have been a few typos, but there was no foul language, there was no wishing anyone else dead, there was no attempt to humiliate anyone. It was just clear and straight information.

Nobody - 2011/10/20

Bob,

Do you find any discrepancy in this document?

This is exactly the kind of thing I'd like to see on US Hawks!!!

Thanks Nobody!!

bobk - 2011/10/23

As for Nobody's request for me to read a document, I haven't found the time yet. I'm sorry, but I don't have time to read everything that everyone asks me to read.

Bill Cummings - 2011/10/26

Very fine effort Tad.

[TadEareckson]

bobk - 2011/11/24

Another excellent article!!!

If Tad wrote like that (and maybe he has at other times and places) then we'd be getting along splendidly. Sure, there may have been a few typos, but there was no foul language, there was no wishing anyone else dead, there was no attempt to humiliate anyone. It was just clear and straight information. This is exactly the kind of thing I'd like to see on US Hawks!!!

Ya probably oughta worry more about the typos than foul language, wishing people dead, and attempts to humiliate people.

1. The problems with that rather short article are NOT typos. Typo connotes mistake small enough that the author is unlikely to notice it. This thing's a literary and logical disaster area. You're not reading someone too concerned about doing a good job, getting things right, or looking like or being a professional.

2. Who gives a rat's a** about foul language and wishes for people to die and be humiliated in the field of aviation anyway? The most professional, competent, and highly evolved aviation organizations on the planet are dedicated to nothing but killing and humiliating people. Two and a half months ago I was at Pearl Harbor where - seventy years ago come Wednesday - Japanese naval aviation beat the crap out of the US military forces we had pointed in the direction of their interests. Killed a lot of people and humiliated the hell out of this country.

3. And when LOTSA people die in aviation, the people involved in and running it either get their s*** together fast, find new hobbies, or get shot for dereliction of duty. Hang gliding's kill rate is low enough that it can get away with defining it as normal - inevitable cost of doing business. You don't think it would at least help a lot of hang gliding better understand towing and weak links if we had a couple of good YouTube videos of both Davis and Jim breaking their freakin' necks in 130 pound Greenspot induced whipstalls? That would just HAFTA go hundreds of miles farther than just clear and straight information. You can do just clear and straight information in this sport till hell freezes over and very little good will ever come of it.

Anyway... Let's do a little dissection.

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.

You can stop right there. You can make it even shorter with:

Tost Flugzeuggeratebau

Weak links protect your aircraft against overloading.

Anybody sticks an "and" or "but" onto that you should either look for another school (on some other planet, I'm afraid) or start understanding sailplaning and thinking for yourself.

Lockouts can and do occur without increasing tow tension up until the point where the glider is radically diverging from the direction of tow.

Translation: Lockouts are only dangerous low and if you rely on a Straub/Rooney Link as a device to protect YOU (and your glider) from slamming back into the runway...

Steve Kroop - 2005/02/09

A weak link is there to protect the equipment - not the pilot. Anyone who believes otherwise is setting himself up for disaster.

...you are setting yourself up for an extremely unpleasant surprise.

At this point tension rises dramatically...

Translation: A one and a half G weak link will blow a millisecond after a three quarter G weak link so if you're stupid enough to try to use a weak link as lockout protection the resulting massive head and neck trauma that will kill you will be virtually indistinguishable between the two rating options.

Given that a certified glider will take 6-10G positive a 1.5G weak link as opposed to a standard 1G weak link should not significantly increase the risk of structural failure.

1. Rot. A half G's difference - call it 150 pounds - will make no difference whatsoever. If it DOES make a difference your glider was about to fall apart and kill you anyway.

2. A STANDARD one G weak link? Whose "standard"? What's the basis for this standard? What's it supposed to do or NOT do? Keep you from breaking up, stalling, locking out, getting out of position, getting into too much trouble, being dragged? Does it infallibly and automatically release the glider from tow whenever the towline tension exceeds the limit for safe operation? Does it increase the safety of the towing operation? PERIOD? Does it hold when you're standing on your tail and going up like a rocket to keep you from whipstalling?

It will however significantly decrease the probability of an unwanted weak link break.

PRECISELY.

Consider a standard tow force of up to 0.8G...

The math all checks out.

I use a stronger weak link for the simple reason that low level weak link breaks are dangerous as the glider may not recover from the probable ensuing stall prior to hitting the ground.

Great. So what have you been doing to...

Davis Straub - 2008/04/23

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).

...clean up your idiot national organization...

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.

...get Davis under some kind of control...

Adam Parer - 2009/11/25

Gulgong Classic
New South Wales

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.

Davis Straub - 2005/01/13

Tom Lanning had four launches, and two broken weaklinks and a broken base tube.

...and prevent this kind of crap and carnage?

They are also dangerous in tailwind launch conditions although you should never take of tailwind in anything stronger than you are willing to land in.

When I leave out of BWI they don't have a plan for when all the thrust is lost right after we get off the ground.

In my opinion these problems presents a far bigger risk than that of structural failure.

Really. In your OPINION this:

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

is still true and we're PROBABLY not gonna be breaking up too many six and up G gliders by adding another half G to the "standard" weak link.

In my experience weak link breaks cause numerous problems...

In whose experience DON'T weak link breaks cause NOTHING BUT problems?

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.

After how many of those blows were those idiots saying, "Whoa! I sure am glad the focal point of my safe towing system kicked in to increase the safety of the towing system!"?

...whereas thanks to the quality of today's gliders structural failure is almost unheard of.

It's one hundred percent TOTALLY unheard of.

Yeah, I do know of on incident where a pilot locked out and was pulled through a previously straightened down tube leading to partial structural failure – the pilot was OK.

1. What does that hafta do with weak links? If someone not on tow slams or falls into the keel he can break it.

2. HOW THE HELL did he manage to get screwed up enough to be pulled into a downtube by a towline? I've NEVER heard of anyone even touching one in a lockout.

3. Even if you did get pulled into the downtube wouldn't the glider just roll away to the other side?

In the event of a lock out I plan to release, and release early...

Ya know what? EVERYBODY *PLANS* to release, and release early. The problem is that when the actual s*** hits the actual fan...

Bill Bryden - 2000/02

Dennis Pagen informed me several years ago about an aerotow lockout that he experienced. One moment he was correcting a bit of alignment with the tug and the next moment he was nearly upside down. He was stunned at the rapidity. I have heard similar stories from two other aerotow pilots.

Paul Tjaden - 2008/07/22

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.

...NOBODY actually *CAN* release before the lockout is pretty much over. So do yourself a big favor and make sure you never get into a lockout within striking distance of the ground.

...because I know

that by the time my weak link breaks (no matter how weak) the glider is likely to be diverging from the tow direction in a steep bank and dive.

1. How carefully did you proofread this article?

2. Ya know what? By the time you react and release (even if you've got your finger on the trigger) the glider is likely to be diverging from the tow direction in a steep bank and dive.

If my release fails...

1. "If my release fails" is not an acceptable beginning of a sentence in hang gliding.

...the weak link will still break before the glider.

A second or two before it and you will be a smoldering heap in a crater off the side of the runway if you're low.

This being said it is still far preferable to use low tow tension, headwind launch, and a standard weak link.

Helen McKerral - 2009/06/29
South Australia

The three times I narrowly avoided injury when car towing was purely through luck, not skill (stopping was not an option - I could only screech, MORE TENSION MORE TENSION MORE TENSION and hope the vehicle had enough oomph to get me up).

1. She's one of yours, you guys were towing her at the time, I'm not a fan of low tension.

2. Headwinds don't always stay headwinds.

3. Oh. It's STILL FAR *PREFERABLE* to use a "STANDARD" one G weak link.

-a) I'm having just a little bit of trouble resolving that statement with:

I use a stronger weak link for the simple reason that low level weak link breaks are dangerous as the glider may not recover from the probable ensuing stall prior to hitting the ground.

-b) So a "standard" weak link won't stall OTHER people into the ground - just YOU. So what makes YOU so special?

-c) How 'bout Helen? What happens when her "standard" weak link blows when she's screeching MORE TENSION MORE TENSION MORE TENSION and hoping the vehicle has enough oomph to get her up?

The bridle set up is the pilots responsibility - after all they depend on it

And meanwhile, back in the REAL world...

Jim Rooney - 2011/08/31

See, you don't get to hook up to my plane with whatever you please. Not only am I on the other end of that rope... and you have zero say in my safety margins... I have no desire what so ever to have a pilot smashing himself into the earth on my watch. So yeah, if you show up with some non-standard gear, I won't be towing you. Love it or leave it. I don't care.

So please, find me something... that you didn't make... that I can go out and buy from a store... that's rated and quality controlled... that fits your desire for a "non one size fits all" model, and *maybe* we can talk.
But you see... I'm the guy you've got to convince.
(or whoever your tug pilot may be... but we all tend to have a similar opinion about this)

You've not heard about strong-link incidents.
Uh, yeah... cuz we don't let you use them.

The weak link forms an integral part of the bridle set up.

adi - 2009/07/02

From what I can gather the US has some quite different (dated?) ways of doing things which it appears are not used here in the UK, and some of the reasons I've heard cited for not using these methods relate directly to accidents in the US.

For instance, the idea of tying your own weak link is absolute nuts to me, as is using a bit of string for the job! Over here it's aluminium only (sailplane style link) and if I turned up with a bit of tied string, I'd be shown the exit road.

That'll come as something of a surprise to a lot of European flyers.

It should be made and tested by the pilot.

Yeah, right. Good luck finding a flight park that has a clue what value weak links they're using - let alone a pilot.

If the knot comes undone then the pilot should learn to tie a better one.

Yes. Everybody should start with shoddy knots and keep tying better ones until he gets to something that actually holds.

The weak link will only break at a consistent load if the string snaps, not if the knot comes undone.

Duh.

Higher climb rates and heavier glider/pilot combinations will inevitably need stronger weak links. One size weak link does does not fit all.

Sure.

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.

If you say so.

If they keep breaking make them stronger.

Davis Straub - 2011/08/26

We had six weaklink breaks in a row at Zapata this year.

Jim Rooney - 2007/07/22

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.

Alternatively reduce tug climb rate to decrease tension...

Great idea!

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.

The weak link breaking strength should be between 100% and 150% of the combined weight of the glider and pilot (the gross load) being towed...

'Cause if we have the tug climb a couple of miles per hour above stall speed its pilot will get fewer bugs blown into his face and we really don't need to worry about...

I use a stronger weak link for the simple reason that low level weak link breaks are dangerous as the glider may not recover from the probable ensuing stall prior to hitting the ground.

...dangerous low level weak breaks anyway. Weak links just increase the safety of the towing operation. Period.

Use your personally tested stuff exclusively.

So yeah, if you show up with some non-standard gear, I won't be towing you. Love it or leave it. I don't care.

The way the weak link is set up does influence its breaking load...

This is all pretty much rubbish. For the weak link and bridle materials we most commonly use you can figure on losing about half the breaking strength - such that a loop equals close to the breaking strength - and it matters very little where knots are positioned. But there's no good reason not to form the loop with a Fisherman's Knot joining the ends and centering the Fisherman's Knot in the Double Lark's Head you use to install the loop on a bridle eye.

Have a bridle system that is as foolproof as possible.

Why?

Jim Rooney - 2009/11/02

Oh yeah... an other fun fact for ya... ya know when it's far more likely to happen? During a lockout. When we're doing lockout training, the odds go from 1 in 1,000 to over 50/50.

Shouldn't we do it the way the professionals at Quest do with as many ways to allow the system to fail as humanly possible? Thin material with bulky ends, four foot secondary bridles, six inch weak link loops, crap weak link protection, bent pin releases, inaccessible actuators?

Remember nothing is absolutely foolproof because fools are just too damn ingenious.

So what? When you're using Industry Standard equipment it's already f*cked up about as much as is possible to begin with.

Make sure all your stuff is good stuff. Check you stuff works. Personally put your own stuff together. Check you have put all your stuff together right – remember glider, harness and tow bridle are all essential elements of your stuff.

Good luck. And who puts his own stuff together anyway. They get told what to use and sold whatever the flight park is selling. And the flight park sells whatever junk is cheapest and easiest for them to slap together.

Accept that tug pilots come in all flavours - the good, the bad and the ugly.

You left out the most popular and important category - off the scale stupid. Evil shoulda been prominent on the list as well.

Do your part right and make their job easy.

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.

Jim Rooney

2007/07/22

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.

2008/11/24

I've personally refused to tow a flight park owner over this very issue. I didn't want to clash, but I wasn't towing him. Yup, he wanted to tow with a doubled up weaklink. He eventually towed (behind me) with a single and sorry to disappoint any drama mongers, we're still friends. And lone gun crazy Rooney? Ten other tow pilots turned him down that day for the same reason.

We're not the ones responsible for making the jobs hell for all - but mostly us - concerned.

If you feel they could give a better tow give them the feedback they need to do this.

You do your job and keep your equipment up to specs and I'll do mine and keep my equipment up to specs. And, otherwise, what's on MY glider is none of YOUR goddam business.

Diplomacy may be required.

You do your job and keep your equipment up to specs and I'll do mine and keep my equipment up to specs. And, otherwise, what's on MY glider is none of YOUR goddam business. And I'm PAYING for that rope. Asshole.

Remember hooking onto tow is an article of faith on both ends of the line.

Mike Van Kuiken - 2005/10/13

The weak link broke from the tow plane side. The towline was found underneath the wreck, and attached to the glider by the weaklink. The glider basically fell on the towline.

Now name me a tug that's been killed by a glider.

None of this is rocket science. It is basic physics combined with elementary mechanics.

Kinsley Sykes - 2011/08/31

Well actually he didn't. But if you don't want to listen to the folks that actually know what they are talking about, go ahead.

Feel free to go the tow park that Tad runs...

And what percentage of tug and glider drivers are you imagining are capable of crunching fourth grade math and science? Ever wonder why everybody's been using NOTHING but 130 pound Greenspot for twenty years no matter how many hundreds of gliders they see it crashing?

If things go wrong analyse why and fix the problem.

Good luck.

Develop the most foolproof system possible.

Jim Rooney - 2010/12/16

Notice how I'm not saying to not do it.
Go forth and experiment. That's great... that's how we improve things.
I'm just warning you of that chasm.

A few years ago, I started refusing to tow people with home made gear.
I like the idea of improving gear, but the lack of appreciation for the world they were stepping into didn't sit with me.
For example... flying with the new gear in mid day conditions?
Are you kidding me????

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.

And try getting it into circulation. By the way... What have YOU guys been doing to get both-hands-on-the-basetube releases up in the air? Or is that just not a real issue?

Follow 1-9 then relax and enjoy stress reduced towing.

Yeah? Try flying at over two hundred pounds on Industry Standard 130 pound Greenspot and/or...

Jim Rooney - 2007/08/01

Whatever's going on back there, I can fix it by giving you the rope.

It's more of this crappy argument that being on tow is somehow safer than being off tow.

...behind some brain damaged piece o' crap with some string on his end that hasn't been inspected it three months and see just how much YOUR stress is reduced.

If you REALLY wanted to do something to make things better you'd get out in the battlezones and give some covering fire to the people on the front lines.

bobk - 2011/11/24

Another excellent article!!!

If Tad wrote like that (and maybe he has at other times and places) then we'd be getting along splendidly.

There are some chunks of good information in there but if Tad wrote like that he'd slash his wrists.