Weak links

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=31855
German engineering comes to weaklinks

win Dfried - 2013/04/16 11:42:36 UTC

Dear Mark, dear Davis,
obviously they can't work if they are misused in the above described way.

Hang and paragliding have been doing pretty much NOTHING BUT misusing weak links for their entire histories.

I do both aerotow and static winch tow with german technology.
For aerotow i need 90 kg weaklinks as the standard 80 kg tend to break too early (heavy pilot).

NOBODY needs 90 kg weak links for ANYTHING.

90 kilograms is 198 pounds. The heaviest glider for which that's even legal - 0.8 Gs - in the US is 248 pounds max flying weight. And we just had a guy killed over here because his weak link blew at 1.0 times actual flying weight.

For over/under winch tow we use the 150 kg weak link for the single pilot, and the 200 kg for the Tandems.

So your surface towed solo gliders are two thirds stronger than your aerotowed gliders.

I can state that in most cases when I broke weak links, I was anyway in a bad situation...

And, of course, that's what your weak link is for. To break in bad situations - not to protect your aircraft against overloading. So at what tension - pounds, kilograms, Gs - does a situation become bad?

...and reaching for the release already.

Meaning that if you'd been using a release that didn't require a reach you'd have been off already and in better shape and your weak link would've been totally irrelevant.

Part of correct use of calibrated weak links however is also to exchange them after a long day of towing, to deal with tiring material.

Bullshit. If your weak links are up to safe ratings they're not even gonna know they were towed that day.

The misunderstadings when discussing german/european towing technology versus anglosaxonian comes from a very basic difference in paradigma:
Here the weaklink is part of the tow rope, and thus in the responsability of the winch operator or the tug pilot.

Nah. None of you, or us, motherfuckers have ANY understanding of weak links: continental Europe, Britain, North America, Australia, New Zealand...

As I have understood the reports here, the weaklink out of the DHV-world is part of the release and thus in the responsability of the hangglider pilot.

- Put the fuckin' weak links wherever you want as long a there's no way they can be taken out of the equation by a wrap.

- It's the glider's ass on the line and he should be able to use a one and a half to two G weaklink regardless of what some asshole on the safe end of the string feels comfortable with.

I have to admit that here are also sites, where textil weaklinks are in use, and they also work fine (don't break prematurely, but still in critical situations).

You're full of shit.
- A weak link that can break in ANY situation - even if the load is starting to threaten the glider - can kill the glider.
- Zack Marzec was in a fairly normal situation that the focal point of his safe towing system instantly converted into a lethal situation.

The new ones tested by the DHV this spring come from an aero towing club, where operators wanted to change from textil to calibrated metal stripes.

No fuckin' way would I go up on 90 kilograms. Nobody with a functional brain would elect to.

Other makes are available since many years:
e.g. here:

http://www.drachenfliegenlernen.de/shop/schleppzubehoer/sollbruchstelle.php

Sollbruchstellen für Gleitschirm- +Drachenschlepp
erhältlich in den Stärken 80kg, 90kg, 100kg, 120kg, 150kg, 200kg.

Tost knockoffs. Gimme the 200 and I'll be happy enough.

Choose wisely ! Regards W.

Based on what?

To choose wisely ya don't gotta be all that wise. You just gotta be able to take your glider's max certified flying weight and multiply by 1.5.

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=31855
German engineering comes to weaklinks

Sam Kellner - 2013/04/16 11:53:26 UTC

Gordon Rigg - 2013/04/16 10:17:32 UTC

A more expensive engineering solution is not necessarily better.

What Gordon said.

Yeah Sam, you da go-to man on towing equipment. Asshole.

Davis Straub - 2013/04/16 12:08:13 UTC

I thought the problem with the over engineered (and wrongly engineered) German weaklinks was so obvious that I really didn't have to do into details.

I thought the same thing about bent pin barrel releases, long thin bridles, and 130 Greenspot standard aerotow weak links. But a couple of decades later... here we all still are.

Davis Straub - 2013/04/16 15:20:09 UTC

While DHV may have approved this, I hope they haven't made this style of weak link compulsory!

Nah, Davis, perish the thought that a bunch of total assholes who have no fuckin' clue what they're talking about...

http://ozreport.com/12.081
Weaklinks - the HGFA rules

Davis Straub - 2008/04/22 14:47:00 UTC

Here is the requirement from the 2007 Worlds local rules (which I wrote) for weaklinks:

Pilots must use weaklinks provided by the meet organizers and in a manner approved by the meet organizers. All weaklinks will be checked and use of inappropriate weaklinks will require the pilot to go to the end of the launch line to change the weaklink.

...should ever do anything so insane as to make a particular flavor of weak link compulsory.

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.

Well, that is always their next step.

Ask the Greeks.

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.

http://groups.yahoo.com/group/TTTFlymail/message/11545
Cart stuck incidents

Keith Skiles - 2011/06/02 19:50:13 UTC

I witnessed the one at Lookout. It was pretty ugly. Low angle of attack, too much speed and flew off the cart like a rocket until the weak link broke, she stalled and it turned back towards the ground.

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=31855
German engineering comes to weaklinks

William Olive - 2013/04/17 00:32:01 UTC

Aren't these a version of the Tost weaklinks?

Yes. Without the overbuilt housing and connectors needed to accommodate the heaviest sailplanes.

I'm with Gordon...

No shit.

...why do we keep on trying to engineer complex solutions...

What do you mean "WE"? What the fuck have you and your ilk ever bothered to engineer? Hell, what the fuck in the way of actual engineering have you and your pin bending ilk ever bothered to even adopt after someone else has done all the work?

...to a problem that doesn't exist.

- Blown Davis Link, dead advanced tandem aerotow instructor, absolutely no clue what went wrong, dedicated thread locked down after 196 posts.

- Yet another weak link discussion, two camps - one and half Gs versus 130 pound Greenspot for everyone 'cause we've always done it this way and we know what we're doing, thread locked down after 174 posts.

- Eternal raging debate on actual strength of 130 pound Greenspot.

- No Billo, there is no problem with weak links for any of you Dragonfly motherfuckers. You:

-- have them on the ragged edge of sustainable tow and can fix whatever's going on back there by giving us the rope

-- can write on the fatality report either that the guy thought he could fix a bad thing and didn't want to start over or that he just froze if it's somebody nobody likes or it was an inexplicable freak accident if it's somebody really popular

Gawd I'd love to see you vaporized in a big fireball sometime soon.

Gordon Marshall - 2013/04/17 01:11:24 UTC

I am totally with Gordon on this one.

Who isn't? Why would anybody not be with Gordon on this one when he knows perfectly well that if he presents a new and better idea and starts making progress with it Davis will lock the thread down and threaten to ban him?

an overly complicated fiddly piece of beautiful engineering is absolutely out of place in the environments that hang gliding towing operations exist.

Fuckin' right, dude...

http://ozreport.com/forum/viewtopic.php?t=22308
Better mouse trap(release)?

Jim Rooney - 2010/12/16 18:47:05 UTC

Oh, I've heard the "everything we do is an experiment" line before.
The trouble is, it's not.

I've seen experimentation with towing gear more than anything else in HG.
I've not seen many go out and try to build their own sails for example. When someone does, they're very quickly "shown the light" by the community. Example... the guy that was building the PVC glider in California somewhere.
But for some reason, towing gear is exempt from this.

The difference is what we do has been done by thousands of people already. It's been tested... a lot.
What we do is free of the experimentation part.
It's still dangerous, but not at the level of building new gear is. Not even close.

That's what people fail to realize.
It's no small difference. It's a huge chasm.

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.

Don't you think that if it were really possible to manufacture something like that somebody would have by now and we'd all be using it already?

Tow pilots have enough on their plate with the stuff they have no control of without having to deal with stuff they do (or should) have control of.

The LAST thing the people who run these operations want the glider people to have is control of their situations. If we failed to keep beautiful engineering out of the environments in which hang gliding towing operations exist those environments would no longer exist as we know them. And we'd have to toss out our long track records and start working on new ones. Can't permit anything like that to happen.

KISS

KISS my ASS, dickhead.

the 'Linknife' is a very simple solution, simple, robust, easy, quick and easy to use.

Sure...

http://groups.yahoo.com/group/skysailingtowing/message/6726
Weaklinks

Peter Birren - 2008/10/27 23:41:49 UTC

Imagine if you will, just coming off the cart and center punching a thermal which takes you instantly straight up while the tug is still on the ground. Know what happens? VERY high towline forces and an over-the-top lockout. You'll have both hands on the basetube pulling it well past your knees but the glider doesn't come down and still the weaklink doesn't break (.8G). So you pull whatever release you have but the one hand still on the basetube isn't enough to hold the nose down and you pop up and over into an unplanned semi-loop. Been there, done that... at maybe 200 feet agl.

Except when you actually need it. Then you find yourself popping up and over into unplanned semi-loops at maybe two hundred feet AGL. Or maybe one hundred feet AGL.

Jim Gaar - 2013/04/17 02:54:24 UTC

A Peter Birren Design

The guy can do no wrong. If only we could get in and see what he's saying in his forum we'd know EXACTLY what the problem with Zack Marzec's flight was.

I've had a number of these for a long time.

Really?
- I'll bet they have a really long track record then.
- I didn't hear you say that you actually used any. Did you actually use any?
- In your five years as Safety and Launch Marshal for Adventure AirSports did you ever insist on this superior technology being utilized?
- Why not?

The only complaint I've ever heard is that you have to put in a new weaklink each time.

- Of course. Anybody who dares question the Infallibility of Saint Peter's Sacred X-Acto knife blades gets banned within two or three posts.

- I've heard that they can be disabled by...

http://ozreport.com/9.047
Avoiding Linknife failures

Phil Wainwright - 2005/02/27

We've been using Linknives here in Western Australia for many years now for both car and aerotowing. From thousands of tows there have been only a couple of release failures. These have been due to either the release line twisting around the Linknife, or wheat stubble becoming jammed in the "v" of the blades.

...an ill mannered lanyard or a little bit of grass in the mechanism. None of my releases have either of those issues.

My reply would be, "Really!? "

What would your reply be if I asked you:

- to find me a video of one being used at any competition or mainstream aerotow operation?

- how it could possibly be as good as any of the spinnaker shackle or bent pin barrel releases Quest has been perfecting for twenty years?

- if it IS better then why:

-- wasn't Bobby Fucking-Genius Bailey insisting that Robin Strid use one instead of the spinnaker shackle job on which he towed him to his death after a jam?

-- isn't everybody using them already? Doesn't superior technology quickly and automatically rise to the top in this sport?

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=31855
German engineering comes to weaklinks

Allen Sparks - 2013/04/17 04:04:40 UTC

Re: A Peter Birren Design

I've been flying 36 seasons, just started my 37th. I rarely tow ... Although I own a linkknife, I have never used one ... but I have alsways understood that it is a release.

I dunno...

http://groups.yahoo.com/group/skysailingtowing/message/6726
Weaklinks

Peter Birren - 2008/10/27 23:41:49 UTC

So you pull whatever release you have but the one hand still on the basetube isn't enough to hold the nose down and you pop up and over into an unplanned semi-loop. Been there, done that... at maybe 200 feet agl.

My feelings about releases are that you should be able to blow them without popping up and over into unplanned semi-loops at maybe two hundred feet AGL. Where are you on this issue, Allen?

I have several very naive questions?

I have one of my own? Why put a question mark at the end of a statement.

What is the purpose of a weaklink ?

Everything you need to know about weak links:

Tost Flugzeuggerätebau

Weak links protect your aircraft against overloading.

A tiny percentage of what you need to do to get that point across to hang gliding people:

http://www.hanggliding.org/viewtopic.php?t=26870
weak links

Allen Sparks - 2012/08/13 17:42:47 UTC

I don't aerotow much. Check out:
http://www.kitestrings.org/
...the thread on weak links.

With this one 824 posts (10394 hits).

Is the purpose of a weaklink to act as a tow release ?

Sure. If you're confident that you'll always be able to hit a set towline tension before hitting the ground and don't care what's going on when you reach that tension, why not? It's a proven system that works and has a huge track record, after all.

Does one size weaklink fit all pilots, regardless of their weight and what type of tow bridle they are using?

If you're flying behind Bobby or Rooney, using the new and improved Lockout Mountain Flight Park Release, and/or at the front of the launch line at one of Davis's pecker measuring contests it does.

I'm not really clear on this. ...

Why not? Didn't the people who signed you off on your Aerotow and Platform Launch Special Skills thoroughly cover the focal point of your safe towing system?

Is there a definitive source of information that would answer these questions?

http://www.tost.de/ESollbruchstellen.html

P.S. Wouldn't it have been a good idea to discuss this and get things thoroughly sorted out BEFORE Zack Marzec was killed? Like:

-- T** at K*** S****** is trying to do?

-- Tad of Capitol Hang Glider Association was trying to do when the motherfuckers gave him a "three month suspension" on 2008/12/12 and backed Rooney and Highland Aerosports?

[groundeffect]

Guys, have you seen this video?

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

[Tad Eareckson]

Yes.

http://www.kitestrings.org/post3290.html#p3290

[groundeffect]

My bad! I've read a lot here but missed that one. That video popped up when I was looking for Dacron.

[Tad Eareckson]

824 previous posts in the thread, 4164 previous posts on the forum. You can be forgiven for missing one - especially if you can find a source for a spool of good 250 pound Dacron.

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=31855
German engineering comes to weaklinks

Ultralajt (Mitja) - 2013/04/17 04:52:57 UTC

Re: A Peter Birren Design

When everything at aero towing goes as it should, the tension on the towing rope is rather small.

Yeah Mitja, it's totally unthinkable that everything would be going as it should with the tension being rather large.

It became larger when for instance glider rises angle of attack, or other uncommon-unwanted situations.

At unwanted situations, for instance that glider follow the tug wrong way (larger cicrcle diameter than a tug in a turn, different heading of the glider than a tug, extreme angle of attack of the glider, sudden tensioning of slack rope..combination of these) the tension in the towing rope became large.

Or when you're towing up in very benign weather conditions with light winds and blue skies and at 150 feet hit this monster thermal that popped the tug up a few seconds before. You stuff the bar and the tension becomes rather large.

This is the kind of situation when you really appreciate having a Rooney Link. It's a bulletproof guarantee that when aerotowing isn't going as it should you'll never hafta worry about the tension on the towing rope becoming very large.

In extreme situations this is often combined with a situation that things starts to develop very fast and pilot of the glider holding control bar both hands is occupied with solving unwanted flight attitude, unable to grab the tow releasen in time...

What if:

- solving the unwanted flight attitude was a problem for which killing your thrust were not an advisable component of the solution?

- you put the fuckin' tow releasen on the fuckin' bastetuben so - if dumping the fuckin' towlinen WERE a good idea - you didn't hafta let go to fuckin' grab it?

...in such moments tow weaklink should broke and save the day.

Yep.

http://www.youtube.com/watch?v=VYe3YmdIQTM

http://4.bp.blogspot.com/-bRrpHNa68iY/UQ6Pv9gRZyI/AAAAAAAAjTg/Hc22bx5122Q/s2048/20943781_BG1.jpg


That's our expectation anyway.

Of course problem is not solved for sure when weaklink broke, when glider is low over "unlandable" terrain

But the important thing is that you'll be off tow and there's nothing really bad that can happen to a glider off or coming off tow.

Bytheway, forces on the rope at aerotowing are smaller than forces at winch towing...

For a given climb rate - yes.

...so weak links should be selected accordingly.

Why? Because light weak links are better at...

http://ozreport.com/17.028
Zach Marzec

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Zack C - 2013/02/15 01:53:11 UTC

My only point in posting the video was to demonstrate that weak links cannot prevent attitudes that could be catastrophic near the ground.

...preventing attitudes that could be catastrophic near the ground?

Davis Straub - 2013/02/15 02:04:29 UTC

I can't imagine anyone arguing that they would.

Aerotowing rope is tensioned mainly with a glider drag force (if we are not meticuolus), while winch rope is tensioned by resultant of gliders lift, drag and weight and it depends of the climbing and AoA angle of the glider on winch tow.

- They're doing the exact same thing - but aerotowing is doing it more efficiently.

- When you look at surface towed gliders coming off launch dollies and aerotowed gliders getting rocketed up in thermals behind tugs the distinctions between the two flavors tend to get a bit fuzzy so one should be very careful about making statements about using different weak links for different towing modes.

- And when you understand what the function of a weak link is you don't consider the tension at which the glider's being towed. You only consider the tension which the glider can withstand.

Gordon Marshall - 2013/04/17 07:37:01 UTC

Re: A Peter Birren Design

Allen Sparks - 2013/04/17 04:04:40 UTC

Is there a definitive source of information that would answer these questions?

The book "towing Aloft' is a good read

Yeah. If there's something you do or don't wanna believe about weak links you'll be able to find it in there. That's what makes it such an excellent book and so popular with such a wide range of glider divers, tug drivers, and tow operators.

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=31855
German engineering comes to weaklinks

Deltaman - 2013/04/17 08:20:47 UTC

Re: A Peter Birren Design

Ultralajt (Mitja) - 2013/04/17 04:52:57 UTC

...pilot of the glider holding control bar both hands is occupied with solving unwanted flight attitude, unable to grab the tow releasen in time..

WHICH SOLUTION?

...in such moments tow weaklink should broke and save the day.

BUT..

Of course problem is not solved for sure when weaklink broke, when glider is low...

Or, if it tailslides, whipstalls, and tumbles high.

BETTER SOLUTION ?...

No, let's make absolutely certain we've totally exhausted all the really crappy and totally insane ones first.

reliable release with 2 hands on the bar : 1 point mouth releases or 2 points lanyard

If that were really a good idea then how come everybody isn't doing it already?

FAA:

...safety link installed at the point of attachment to the glider with a breaking strength of not less than 80% of the glider's MAXIMUM CERTIFIED TAKE-OFF WEIGHT but not more than twice the glider's MCTOW.

What point in that range is best for meeting our expectation of break as early as possible in lockout situations but being strong and reliable enough to avoid frequent breaks from turbulence?

Mike Lake - 2013/04/17 09:42:35 UTC

Re: A Peter Birren Design

Ultralajt (Mitja) - 2013/04/17 04:52:57 UTC

Of course problem is not solved for sure when weaklink broke, when glider is low over "unlandable" terrain.

Or indeed over perfectly landable terrain upside down or in a dive.

http://ozreport.com/forum/viewtopic.php?t=15716
weak links

Marc Fink - 2009/04/15 12:56:14 UTC

In not one single accident report do I recall the conclusion that the use of an understrength weaklink was the cause of the accident--despite your assertions to the contrary.

Marc Fink - 2013/04/17 14:49:11 UTC

Looks kinda like a Bauhaus tampon. : )

Vacuous little Davis Show twat. Hey Peter... Your name has been used in a post title six times so far in this thread. How 'bout emerging from your Sacred Sanctuary and...

http://groups.yahoo.com/group/skysailingtowing/message/4593
Weaklinks

Peter Birren - 2005/02/08 19:22:49 UTC

What is the big issue? Re-launching? Oh, the wasted time! Oh, the hassle! Oh, the embarrassment! These are sure preferrable to Oh Shit!

...clearing this weak link issue up for everyone for once and all?