Kite Strings

I have no more reliable and objective datas to give

I'd like to say:

I haven't ..

Well, I can recall a time when having a weaklink was very useful for me, here. If you come off the cart early and hit the ground, you'd like the tow rope to break so that you are not pulled along the ground anymore than necessary.

And other examples....

Of course, there are always exceptions.
Sometimes there are road accidents where having NO seatbelt saved a life, a body flung from a burning vehicle for example.
The outcome of the above weaklink example could have been completely different, better or worse, if the weaklink had snapped an instant earlier, later or not at all.
A weaklink is not there to help your crashes, although sometimes it might, sometimes it might not.

Any tow flight takeoff, where you are teetering on the edge of losing the line, without warning, during this most critical time and while at this most abnormal glider attitude, has the potential to kill or hurt you.
Unlike a crash, a lockout or all the other random examples people give for a weak weaklink being better for you,
YOU SUBJECT YOURSELF TO THIS RISK EVERY TIME YOU TAKE OFF.

The fact that this risk is PUT THERE BY DESIGN I find almost unbelievable.
I have my own theories, based on my own experiences in the UK, as to how this teetering dangerous practice seems to have gained worldwide adoption and it has nothing to do with safety or some carefully worked out formula designed to offer the maximum protection.

Most of the time a weaklink break has a mild or insignificant outcome, and can be described as a non event.
Sometimes the outcome is described as a non event ONLY BECAUSE AT THE TIME THE PILOT HAD SUFFICIENT HEIGHT TO SURVIVE. This is definitely NOT a non event.
I would consider our club to be a very safety conscious outfit and yet on 2 occasions this year so far I have witnessed weaklink breaks where the outcome would have been very different for want of 30 or 40 feet.

Next time at the towfield count the number of lockouts, the number of falling off the cart instances, the number of times a pilot is dragged down the runway or any other instance where a weaklink break might be said to affect the outcome. The chances are this will be zero.
Then look at every launch, look at the first dozen feet or so and imagine a weaklink break at that critical point, see how many hits you get.

The vast majority of pilots fly without question with whatever their club/organisation give them. However, there are more then a few pilots not happy with the generally adopted weaklink values inherited from the '80s, although there are none quite a vocal as Tad.
In the future pilots will look back at this era and wonder why we were all so blind when it comes to weaklink values, just as we now look back and wonder why we ever flew without tip sticks or other dive recovery devices.

Regards

Bridlelink

I made an another 6+6 which had an asymmetrical break @98kg !
good, same load but..
asymmetrical breack was not what I expected to keep the interest of a bridlelink even more if I build the asymmetrical bridlelink I wanted (to be attached directly to the webbing loop of the harness..)
Here are pics:
http://www.flickr.com/photos/psucvollibre/?saved=1

WL

I read all the arguments to a wl stronger than we normally use, I understood the logic that was defended here, and read the bad stories of wl failure too..
but as we don't have the datas recorded of all wl failure, and it s hard to say peremptorily what should be the issue if.., it's hard to say how many lifes it killed, and how many it saved..
When there is a low lookout, I understood that you think:

01. Sometimes the air does stuff - often, in our areas of concern, as a consequence of a thermal or dust devil - that makes ANY situation with a low hang glider - launching off a ramp, tow launching, or coming in for a landing - unsurvivable.

or
the pilot wasn't enough skilled to do AT
or
he should have release before to be in trouble, and should have the better release as we can
but

04. Lockouts commonly hit so hard and so fast that - I don't care who you are or how good your equipment is - you can't react and release before they're almost over.

and you consider at all time it would be better with a stronger wl, point of vue I consider and in wich I'm agree most of time, for the matter of stall recovering, hostile areas surroundings..

except that, we are all influenced by our own experiences. And mine give me to see, wl failure in low lookout which saved the pilot for sure (I'm lying cause it wasn't the wl but the old rope which blow! we've got dyneema now) ..but it could be worst too, I admit. Yes the pilot wasn't enough experienced as it was his first AT, with a small rope (45m), with his own C4, in 1:1, in strong wind, in an unstable morning, with a release he never used before as it was his 1st time. What to say? he shouldn't do AT in this conditions. Yaes, I'm agree ..unfortunately he did.. (with the clearance of the old president of my club who was thinking himself enough experienced to teach to the other while he is absolutely crap !! I helped to leave his post since)

..

Bridlelink
Tad,
did you already consider a bridlelink with an overlap of 2 strands only ?

Asymmetrical break of a bridlelink with a long side to the webbing loop

Yeah no matter, the other side will blow immediately in case of a wrap.. Sorry, I write before thinking !

Bridlelink with an overlap of 3 strands ?

Is that possible? It should be as your shearlink..
I could put the single strand on the opposite side of the release (yes I know you prefer 2 releases) with an eye at its end?

WL and Sailplane AT
I discovered today that in France in AT with Sailplane, no wl are used at all !!, except...
the tow rope: 1500daN max
and glider weight: 750kg max
so rope is a 2G MINIMUM weaklink

Antoine,

Happy to have the key now to build bridlelinks...

And I'm OVERJOYED to find that somebody who wants to can duplicate them and come within one percent of target on the first try.

...is that your proper genious idea ? If yes, well done !

Thank you. It was as accidental invention.

I was making towing equipment by stitching Dacron with nylon floss and it occurred to me that I should really test the stitching to see how much it was holding. I did a few tests with different numbers of stitches and noticed that I was getting remarkably linear/predictable results.

LIGHTBULB! "I can use this principle to make weak links to pretty much any value I want!"

I lot of people who had gotten real tired of blowing loops of 130 pound Greenspot - that the idiots running the flight parks were telling everybody held to 520 pounds of towline tension - started lining up for them. But the idiots running the flight parks can't stand anyone trying to make anything better or safer so that was the end of Shear Links, straight pin barrel releases, and yours truly.

...it is advisable to bias selection on the low side.

You really don't need to worry about that.

Originally I was pretty paranoid about hitting very accurate numbers and worried about things holding to over the predicted values. I just meant that if, for example, you were trying to hit 306 pounds - the midpoint between an Eight (288) and a Nine (324) - then the Eight was likely to be closer.

But there's nothing you'd really need a Seven for and the only place you'd want an Eight or a Nine would be on the shoulders of someone towing a very small glider two point.

For any glider with a maximum allowable flying weight of 261 pounds or up you can use a Number Ten or up Bridle Link at the bottom of a two point bridle for maximum safety performance. (And that definitely covers you personally.)

And you could tow a max 180 pound glider one point on a Number Ten - and there are no max 180 pound gliders.

I don't understand this word "bias"

A "bias" towards the lower number... You would "favor" or "prefer" the Eight over the Nine.

...with 3 stitches, they can pull through easily. overlap don't stay tight on this side.

Right. That's the way it's supposed to be.

By the way...

I'm 120kg wing loaded : pilot+harness+glider.

Despite what everyone in hang and para gliding would have you believe...

We don't need to know your FLYING weight.

What we're doing with the weak link is keeping your glider - loaded to the max - from having to deal with more than two Gs of tow tension. So we just need to know the glider and maximum allowable hook-in weights.

Note...

The people that are talking about weak links with respect to ACTUAL FLYING WEIGHT versus MAXIMUM PERMISSIBLE FLYING WEIGHT are trying to use weak links as lockout protectors. That's an immediate tip-off that they don't know what they're talking about.

Is it necessary to stitch the 2 strands before the eyes too ?

Makes things a little neater and it's good if you're going to use the heat shrink Fairings, but... No. IF you do it, however, do it AFTER you do the Strength Stitching because it's a little easier to make sure the leechline elements in the Overlap are evenly loaded. And that stitching isn't at all critical and can be done quickly, easily, and spaced out a bit as you go outboard.

On how long (minimum)...

Doesn't matter, not important.

I feel more and more the necessary not to have a failure...

The bastards that run the flight parks over here gear things so they don't blow weak links on their tandems but really don't give a rat's ass what happens to the solos. That damned 130 pound Greenspot makes life pure hell when you're trying to get up an a good day. Relaunches and waiting in line for other people's relaunches.

So my bridlelink will be stronger...

No.
- On tandem you're always going to be towing two point.
- So you base everything you're doing on the Primary Weak Link (on the top end of the bridle).
- Get the top end weak link as high as you can up to 1.5 Gs (or a little more if the tug and the releases can handle it).

Let's say your glider is a Wills Wing Falcon 3 - max flying weight 571 pounds - max tow tension 857 pounds - primary weak link on two point bridle - (857/2*1.15=) 493 pounds.

- Use a Bridle Link (between your shoulders at the bottom end) a minimum of 1.2 times the top end. 592 pounds. Closest you can get is a Number Seventeen (eight plus nine) - 612 pounds - 1.1 Gs after a Primary Bridle wrap wrap.

OK, in the real world your tug isn't going to be able to handle that much. So let's do 1.0 Gs instead.
- 328 - Primary Weak Link
- 396 - Bridle Link No. 11
- 0.7 Gs after Primary Bridle wrap

1.1 Gs WILL blow after a bridle wrap. 0.7 Gs will REALLY blow after a bridle wrap.

Joe Street...

Real good guy, knows what he's doing and talking about, I think that release will probably be the best you can buy. But I hope you'll build one into the glider - cable always scares me a little bit.

Our microlight...

Yeah. I DON'T like that.

Does the Cosmos still run a towline extension through the propeller shaft? If so...

- I would think that it could take a much heavier weak link.

- (If you don't have one already) I would strongly recommend putting a swivel on the towline just aft of the tug. There was a very dangerous situation at Santa Cruz Flats three years ago in which a bearing froze and the towline rapidly twisted and disabled the glider's releases.

If 190 kg is the best you can make the tug do I'd still keep the tandem at one G. I know that means you get the rope but...

- I'm a lot more afraid of a weak link failure than I am of getting the rope.

- If I die because of weak link failure I don't want it to be my fault. I want it to be because the tug wasn't doing it's job and staying above my LEGAL and APPROPRIATE rating.

- And that's the way I flew - 1.5 Gs on my end, whatever on theirs.

- Bobby Bailey - who has no clue as to what a weak link is - built a light breakaway into the tow mast because he felt that Dragonfly drivers too stupid to put a weak link on their end of the towline deserved to live.

- And, consequently, flight parks now use front end weak links - which limit towline tension to about 200 kg - to protect the goddam breakaway instead of the goddam tug. (They're using a weak link to protect a weak link.)

- Virtually all tandem gliders now fly with weak links heavier than what's on the Dragonfly. The assholes at Lookout have no weak links whatsoever at the glider end.

- It's a crappy way of doing things but they do a LOT of tandems and don't seem to be having problems.

- So you probably won't either.

Actually, I asked for better understanding of the 190kg value and am waiting for answers...

1. If they're anything like US operators the answer may be "Because that's the way we've always done it."

2. There's also a strong possibility that the answer will be "Because that's about what Wallaby uses and Wallaby has been around for twenty years so they must really know what they're doing."

...can you imagine to protect a shear link on the line from the ground...

I developed a Shear Link to try to do that:

http://www.flickr.com/photos/aerotowrelease/8312398111/


http://www.flickr.com/photos/aerotowrelease/8313448522/

but none of them ever flew more than once or twice (thanks, Ridgely) so I don't know how they would hold up and think that if you're going to drag a weak link then Tost is probably the best way to go.

Tost: the one of K.Hammond is 150kg max...

Steve Uzochukwu said that he could make inserts for whatever you want. If that's not the case I'll bet it wouldn't be too hard for someone to make his own. A strip of steel about the right thickness, drill a hole big enough to put it where you want it.

...(UK law, he said)...

UK - and US - law sucks.

...and limit the force to the confortable release actuation tension before. right?

Yeah, but that SHOULDN'T be a reason. My off-the-shelf parachute pin based releases can handle 350 pounds of DIRECT loading (and they're all on an end of a bridle - so around twice that for towline tension) no problem.

But if I had somebody machine a heavier longer pin I could easily handle a totally ridiculous amount of tension.

But the pilot I knew wasn't really skilled enough and too hurry...

Too bad. That's a horrible price to pay for some fairly small mistakes. But there's usually more people than just the pilot to share the blame. You have to have SOME training standards in place.

We didn't practice the 2:1...

2:1? Two pilots to one glider? Tandem?

...don't know about its release but not sure he had time to actuate one.

Probably not. There's not much defense against diving into the ground - on tow or off. But they're have been other situations in which people were dragged simply because they had no way to abort.

But, again, my system is a dead man switch. Even if you're paralyzed - as soon as your hand comes off the basetube you're off tow.

The matter of being dragged and potentially increase the injury was the reason of this story...

I don't know how far he was dragged but - ignoring the issue of him being on the cart with inadequate training - I tend not to fault a tug driver as long as he maintains speed and tension, doesn't climb above me, and doesn't squeeze the lever unless he's being jeopardized by having the glider on tow.

I thank you again for your help...

REALLY want to thank me? Get a couple more people adopting this stuff. Really glad you've got the ball rolling.

Thanks.

I'd like to say...

No, you were right the first time, EXCEPT...

Data is already plural. Latin. Singular: datum.

Now, write it out a hundred times and if it's not done by sunrise, I'll cut your balls off.

(Does France do Monty Python?)

Hey Mike,

Good to see people making life at least a little bit miserable for the bad guys back out there in the world.

Speaking of which...

Well, I can recall a time when having a weaklink was very useful for me, here.

That was a quote from Davis... THIS Davis:

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.

...on 2005/02/08 right after Robin was killed when his shitrigged spinnaker shackle release locked up. It would've been too explosive to admit that there were fifty thousand expensive shitrigged spinnaker shackle releases these assholes had put into circulation with the same deadly flaw (and half a dozen other ones) so they launched a huge international campaign to blame his 1.4 G weak link.

And it worked:

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

Peter Birren - 2005/02/08 19:22:49 UTC
Elk Grove, Illinois

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

http://groups.yahoo.com/group/skysailingtowing/message/4589
Weaklinks

Davis Straub - 2005/02/08 17:08:45 UTC

At the moment most competition pilots use "STRONG LINKS."

And Robin paid the price... is it worth it?

http://www.paraglidingforum.com/viewtopic.php?t=28697
Weak links why do we use them. in paragliding.

Fredrik Sandquist - 2010/01/18 18:31:29 UTC
Trondheim

The hg fatality at Hay. The too strong weak link was one of the reason for the fatality according to the official report if I remember correctly.

Sometimes there are road accidents where having NO seatbelt saved a life, a body flung from a burning vehicle for example.

Another analogy you might want to think about, Antoine...

- There are A LOT of hang glider pilots alive today who definitely wouldn't be if big trees hadn't been growing at the points at which they crashed.

- There ARE DEFINITELY people who've been killed in lockouts at airports who could have climbed down and walked away if they had slammed into big trees.

- That doesn't mean that the way to make towing safer is to plant a lot of trees along the runway.

I have my own theories, based on my own experiences in the UK, as to how this teetering dangerous practice seems to have gained worldwide adoption and it has nothing to do with safety or some carefully worked out formula designed to offer the maximum protection.

I don't see much way it can't be attributed almost entirely to Hewett. Donnell did an absolutely MISERABLE job on towing "theory" - but an OUTSTANDING job on publicity. That Skyting newsletter went out all over the world, including the UK (where, Antoine, it had the effect of burying the much better work Mike and his crowd had already done circa 1979-1982), because he got ONE important thing that made a big difference somewhat right, everybody blindly swallowed everything else in the package - almost all of which was dead wrong.

Most of the time a weaklink break has a mild or insignificant outcome, and can be described as a non event.

Like a little chunks of foam insulation breaking off the external fuel tank and gouging the heat shielding during a Shuttle launch.

This is defiantly...

Definitely? Seems to work either way.

I would consider our club to be a very safety conscious outfit and yet...

I don't think it's an "and yet" issue. The VERY safety conscious outfits DEMAND 130 pound Greenspot and the EXTREMELY safety conscious outfits encourage people to fly with it fuzzed up a bit. I think it's more of an "and so" issue.

Then look at every launch, look at the first dozen feet or so and imagine a weaklink break at that critical point, see how many hits you get.

Or go to an extremely safety conscious operation - like Ridgely or a competition run by Davis (which is pretty much all of them) - so you don't have to imagine anything.

http://ozreport.com/9.011
2005 Worlds

Davis Straub - 2005/01/13

Tom Lanning had four launches, and two broken weaklinks and a broken base tube. He made it just outside the start circle.

Next time at the towfield count the number of lockouts, the number of falling off the cart instances, the number of times a pilot is dragged down the runway or any other instance where a weaklink break might be said to affect the outcome. The chances are this will be zero.

http://groups.yahoo.com/group/skysailingtowing/message/6670

Tad Eareckson - 2008/10/07 17:46:42 UTC

Ridgely has pulled something on the order of forty thousand tows over the course of its ten seasons. Let's be REAL generous and say that they're only breaking weak links at the rate of one per twenty flights. That's two thousand pops. The percentage of those that were desired and necessary for the safety of the flight is ZERO. So what do we learn from these numbers?

Donnell Hewett - 2008/10/14 00:49:34 UTC

We learn that the weak links are consistently breaking before the situation becomes dangerous, exactly as they are designed and intended to do. If you really want to increase the number of weak link breaks that are deemed "desired and necessary for the safety of the flights", simply increase the weak link break point to 4 g's, or better yet, eliminate the weak link altogether.

The vast majority of pilots fly without question with whatever their club/organisation give them.

Stupid clones. (Speaking as a former longtime mostly stupid clone.)

However, there are more then a few pilots not happy with the generally adopted weaklink values inherited from the '80s...

A FEW?

http://www.chgpa.org/forums/viewtopic.php?f=2&t=2467
weak links

Jim Rooney - 2007/07/22 22:30:28 UTC

I've heard it a million times before from comp pilots insisting on towing with even doubled up weaklinks (some want no weaklink). I tell them the same thing I'm telling you... suck it up. You're not the only one on the line. I didn't ask to be a test pilot. I can live with your inconvenience.

There's at least a million.

...although there are none quite a vocal as Tad.

That's 'cause they don't want what happened to Tad to happen to them. They'd rather take a very small chance of getting their necks broken each tow than an almost certain chance of not being able to tow at all.

In the future pilots will look back at this era...

Are you seeing a trend of weak links gradually creeping up in strength and national organizations revising their regulations to specify sane minimums?

...just as we now look back and wonder why we ever flew without tip sticks or other dive recovery devices.

Almost as soon as they came out...

1980/08/23 - Ronald Higgs - 30 - Raven 209 - Lily Pons Hill - Buckeystown, Maryland

Hang IV flyer, Ron was getting "people tows," with his brother and others slinging him along with a pulley/bridle system. On his last launch, he got better wind, rose at 45 degrees to 100', got into a right hand lockout, then a wingover and dive back into the hill. No defined tips or anti-luff lines on the glider at the time.

...some people started taking them back off.

That guy was a guru at my home turf who bought it right after I began flying. He had pulled the defined tips and reflex bridle to "make ground handling easier". Les King - the main man around here at the time - reported watching it and expecting the glider to pull out at any instant now all the way to the ground. Judgment of the rabble... Towing is dangerous - don't do it. Set local towing back the better better part of a decade.

Antoine,

I made an another 6+6 which had an asymmetrical break @98kg !

Hard to beat a zero percent deviation.

asymmetrical breack was not what I expected to keep the interest of a bridlelink even more if I build the asymmetrical bridlelink I wanted (to be attached directly to the webbing loop of the harness..)

I don't understand all of that sentence but...

If I can't talk you into putting releases on both sides, AT LEAST please put a quick link (maillon rapide) between the loop and the Bridle Link so the end doesn't abrade and degrade with tension fluctuation.

...but as we don't have the datas recorded of all wl failure, and it s hard to say peremptorily what should be the issue if.., it's hard to say how many lifes it killed, and how many it saved...

It's extremely difficult for hang (and para) glider pilots to really understand weak links once their heads have been wired wrong about them - there are only about a half dozen that do. But keep trying.

Tost Flugzeuggerätebau

Weak links protect your aircraft against overloading.

That's it. It's not there to keep gliders from slamming into the ground and/or people from getting hurt or killed.

If the glider was in one piece when it slammed in - on or off tow - then an overstrength weak link WAS NOT a relevant issue. The glider slammed in because the pilot - and/or tug driver - failed to or - due to conditions - could not control it.

http://groups.yahoo.com/group/skysailingtowing/message/4633
Weaklinks and aerotowing (ONLY)

Steve Kroop - 2005/02/10 04:50:59 UTC

Weak links are there to protect the equipment not the glider pilot. Anyone who believes otherwise is setting them selves up for disaster.

Even these guys get something right once in a while.

You MUST understand that to understand weak links.

- Yes, there ARE people who are alive who wouldn't be if their weak links hadn't HAPPENED TO blow at good times during lockouts. They LUCKED OUT. They did the equivalent of crashing into a big shock absorbing tree.

- There are also people whose weak links blew during lockouts who died anyway.

- We don't run aviation on a luck model. We run it on a CONTROL model. You don't send an unqualified pilot up with a crappy release system on a light weak link because it MIGHT blow at just the right time to save him from a lockout because if you try to do that you greatly increase the chances that you will kill him with a stall resulting from a weak link failure.

- To run things on a control model you properly train the pilot and driver, equip them with the best towing system money can buy (including a one and a half G weak link to keep the glider from being overloaded), and monitor the runway for dangerous conditions just prior to launch.

...but as we don't have the datas recorded of all wl failure...

This isn't a data thing. This is a thought, logic, physics, understanding thing. But if you want to do data then search the web and find me ONE example of a properly equipped competent pilot - in or out of a thermal or dust devil - saying, "Whoa! It sure was a good thing my weak link blew!"

...he should have release before to be in trouble...

If everyone released before he was in trouble no one would ever get more than ten or twenty feet off the ground. (Kinda like telling people to always get out of the building before an earthquake.)

I'm lying cause it wasn't the wl but the old rope which blow!

ANYTHING that blows in the course of a tow is (was) THE weak link.

Yes, I'm agree ..unfortunately he did..

So what's the point? That if an incompetent operation sends a pilot up solo on a high performance glider and short towline with a release he doesn't know how to use in strong winds and unstable conditions for his first aerotow you should use a worn out rope that blows at an indeterminate tension below the designated weak link because it MIGHT break at a good time in the course of a lockout that MIGHT be high enough to be survivable?

- Can you tell us what the designated weak link G rating was so we can start figuring out the best G rating to save the next flight like that?

- How far did he fall after the towline failure before he recovered?

- If the lockout had occurred at two thirds of the altitude would he have survived? Maybe we should use lower weak link ratings for lower anticipated lockout altitudes.

- How many more times do you think that strategy can be gotten away with before somebody gets killed - zero or slightly more than zero?

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

That was true 37 years ago, it's still true now - on BOTH sides of the Atlantic.

...with the clearance of the old president of my club who was thinking himself enough experienced to teach to the other while he is absolutely crap !!

Yeah, that's a pretty good summary of US aerotowing as well.

...did you already consider a bridlelink with an overlap of 2 strands only ?

NO!
- You'd have to stitch an eye securely enough to ensure that it wouldn't blow before the Strength Stitching did.
- There'd be a serious weak point in the single strand of leechline where the eye stitching ends inboard.
- You'd have an irregularity to the end of the Bridle Link which would cause it to feed through the thimble more roughly if/when released.
- The Bridle Link would be skinnier and you would introduce a wrap potential.

But it's good to keep thinking about different ways to do things anyway.

Yeah no matter, the other side will blow immediately in case of a wrap...

No. If the section of an Overlap is involved in a wrap it won't blow AT ALL - until the leechline itself blows at the retained eye.
But you don't talk about aerotow Bridle Links wrapping because - by definition - they're too short, fat, and stiff to be capable of wrapping.

Sorry, I write before thinking !

Better late than never. (Most of the people in this game are in the never category.)

Bridlelink with an overlap of 3 strands ?

No, you've still got Problems One, Two, and a bit of Four from above.
(By the way... A Bridle Link is a TYPE of Shear Link.)

WL and Sailplane AT

Yes. If only hang gliding had bothered to understand what sailplaning had figured at the Dawn Of Time we'd all be spending more time flying and less time burying people and fighting for sane practices and equipment.

http://www.hanggliding.org/viewtopic.php?t=22233
Looking for pro-tow release

Mike Lake - 2011/06/15 21:47:13 UTC
UK

astronaut - 2011/06/15 13:18:56 UTC

If you are looking for a simple and durable pro tow release I would recommend buying a Koch-2 release from Finsterwalder in Germany.
They have been on they market for years. Are incrediably reliable and sold in millions Never heard anyone complain about them.
They are a bit expensive though, but you get what you pay for

Careful!
The mention of Koch and trying to make any constructive comparison is likely to get an aggressive response and the thread locked down.
Oh no sorry wrong forum.

Just make sure you don't say anything about light weak links or US flight parks being dangerous.

Ok then an aggressive response from Mr. Rooney. Oh no, that's not going to happen either.

Too bad. He was always such a great source of foot shooting quotes. I so do hope he keeps playing Robin to Davis's Batman.

Well then, ok here goes.

Tried that one. Very good and durable system but it is not easy/quick to fix to your harness.

True, but you only do this once. A one time fix and a one time purchase that you will sell on for a good portion of what you paid for it.

Quite a big metal piece, not very advisable if you make a bellylanding once very now and then. Rib cracker.

In reality Koch or Koch types don't crack ribs or "crush chests" any more or less than any of the other bits of chunky stuff you might land on.

Maybe it could happen but in the circumstances where this might be an issue I would guess the pilot would be more worried about their face, neck, back or be too dead to worry at all.

This is only a perceived problem and in over 25 years of use I don't think there are any reported instances of a Koch contributing to anyone's injuries where it matters.

It is an almost insignificant downside in comparison to having a release with such a minuscule failure rate that it is, for all intents and purposes, infallible.

http://www.hanggliding.org/viewtopic.php?t=16384
Tow Release Malfunction

Jim Rooney - 2010/03/26 20:54:43 UTC

What do they call them again? "Chest Crushers"?

1. There is absolutely no documentation of a chest crusher / rib cracker crushing a chest or cracking a rib.

2. Brad Anderson, Eric Aasletten, Frank Sauber, and Robin Strid - who all got stuff like smashed heads, broken necks, cracked ribs, and crushed chests - would've all been fine if they had been using a chest crusher / rib cracker.

http://www.hanggliding.org/viewtopic.php?t=22176
Paragliding Collapses

Jim Rooney - 2011/06/12 13:57:58 UTC

Most common HG injury... spiral fracture of the humerus.

3. But, strangely, NOBODY refers to a downtube as an arm breaker!

Well then, let me be the first!

Landing the U2

Prior to the landing flare your body position should be generally upright, but slightly inclined forward, with your head and shoulders forward of your hips and your legs and feet trailing slightly behind. Many pilots make the mistake of trying to get too upright at this stage of the landing, which actually reduces your flare authority and makes it harder to land on your feet. Your hands should be at shoulder width and shoulder height on the arm breakers. You should be relaxed, with a light grip on the bar, and your weight should be fully supported in your harness and not at all by your arms.

There are several options for when to make the transition from prone to this semi upright position. Some pilots favor going upright and moving both hands to the arm breakers while still at altitude prior to the start of the approach. Others transition at the start of the approach to a semi upright position with one hand on an arm breaker and one hand on the basetube, and complete the transition by moving the other hand to the arm breaker just a few seconds prior to flare. Still others fly with both hands on the basetube until established on final glide, and then transition one hand at a time to the arm breakers prior to flare.

Once established on a wings level short final, into the wind, body semi upright and with both hands on the arm breakers, your final concern is the timing and execution of the landing flare.

There is no other system (one where it is necessary to let go to activate) that releases as quick, as precise or as reliably and with nothing to fly-back and hit you in the face.

It's a trade-off, chunky verses safety.
There are, no doubt, reasons for not using one to aerotow...

Yeah, there's much better, cheaper stuff that doesn't involve ANY tradeoffs.

...but the 'chest crusher' syndrome is not one of them.

P.S. I'm not a spokesman for Koch and I'm not selling anything.

Zack C - 2011/06/16 03:14:35 UTC
Houston

I've never aerotowed pilot-only...

Yeah, we need to do something about that.

...but it is my understanding that this configuration pulls the pilot forward significantly, limiting the amount he can pull in further.

Forget understanding - just stand next to the runway and look.

Similarly, it is my understanding that when the tow line is not centered horizontally in the control frame, the pilot is pulled to the side, limiting the amount he can roll in that direction. The effect is mitigated when the tow force is split to the glider.

This is mostly Skyting mythology. Donnell and his loyal cult members believed that the "center of mass" bridle system pulled the pilot under the leading/high wing, auto corrected, and made lockouts a relic of history. They never figured out that when the pilot is pulled to the left the glider reacts by rolling to the right - leaving everything pretty well centered - and needed to explain why gliders continued to lock out - just not as often, quickly, badly.

So we get crap like this:

Bill Bryden - 2000/02

At approximately 125 feet (estimates by observers ranged from less than 100 up to 150 feet), her glider started turning relative to the towline. Observers did not note corrective action by the pilot. The glider turned enough that the tow bridle strongly contacted the flying wires and/or the pilot strongly contacted the control frame of the glider. The resulting lateral force on the control frame pulled the glider into an aggressive lockout. The glider rolled over extremely quickly and dove into the ground in a manner of only several seconds.

in our fatality reports.

Note that we never get reports of the glider being turned enough that the tow bridle strongly contacts the flying wires and/or the pilot strongly contacts the control frame of the glider in brutal but inconsequential lockouts at altitude.

Yeah, just as a one point pilot will get pulled more forward with respect to the glider the same thing will apply to the lateral stuff. BUT...

By the time you're pointed ridiculously sideways enough for that effect to become measurable the tow ceased being a tow a LONG time ago.

Think about it... When was the last time you heard somebody say, "Dude! I coulda brought it back but I was up against the stops 'cause the towline had already pulled me so far to the left."

Versus something that actually DOES happen in real life:

Dennis Pagen - 2005/01

Soon after lift-off the trike tug and I were hit by the mother of all thermals. Since I was much lighter, I rocketed up well above the tug, while the very experienced tug pilot, Neal Harris, said he was also lifted more than he had ever been in his heavy trike. I pulled in all the way, but could see that I wasn't going to come down unless something changed. I hung on and resisted the tendency to roll to the side with as strong a roll input as I could, given that the bar was at my knees.

Jim Gaar - 2011/06/16 03:54:21 UTC

Hay Pud!!! (Getting ready to try the 2 stage)

Hay Jim!!!

http://www.hanggliding.org/viewtopic.php?t=13689
eating dirt

Jim Gaar - 2009/09/18 19:23:44 UTC

Hell I've literally shoved the control frame out in front of me to avoid a whack when it got a little ahead of me in a light DW landing, similar to when I've had to slide it in on my belly (did that once after a weaklink brake coming off a launch cart.

And don't forget the Greenspot so it will always brake soon enough to keep you REALLY safe.

The issues you describe can happen as well on the COM or 3 point bridle as well.

There's no such thing as a center of mass bridle and nobody uses three point bridles.

I'm with Davis, Zack.

Really? I thought you were...

http://ozreport.com/forum/viewtopic.php?t=23813
Threaded bridle system

Jim Gaar - 2011/05/26 15:44:33 UTC

I'm a Rooney follower.

...a Rooney Follower. Oh well, one asshole is as good as the next. Do both if you really wanna do it right.

It's different yes. One just has to get use to it and compensate for the way a ProTow does it's job.

Yeah, poorly.

The main reason for the 3 point is to minimize bar pressure and to help SS wings point at the tow plane. YMMV

And, if things line up right enough, your mileage accumulation may totally cease.

Davis Straub - 2011/06/16 05:11:44 UTC

Zack C - 2011/06/16 03:14:35 UTC

I've never aerotowed pilot-only, but it is my understanding that this configuration pulls the pilot forward significantly, limiting the amount he can pull in further.

Incorrect understanding.

Similarly, it is my understanding that when the tow line is not centered horizontally in the control frame, the pilot is pulled to the side, limiting the amount he can roll in that direction.

Also incorrect.
There you go.

Zack C - 2011/06/16 12:12:00 UTC

Incorrect understanding.

Incorrect in that the bar doesn't trim any further aft than when the tow force is split to the keel, or incorrect in that this doesn't limit pitch authority?

INCORRECT as in DAVIS just SAID it was INCORRECT. End of story. You DEAF or sumpin'?

Casey Cox - 2011/06/16 12:18:31 UTC

Pro-tow is not as safe a tow bridle as a 2 point with aero release.

That was told to me by Malcolm Jones just April of this year. I specifically asked this question. I thought he was something of authority since he has acknowledgement in Dennis Pagen books and has an aero park since 1991.

Yeah, he's an authority alright. Would've made a great astrologer.

Towing Aloft - 1998/01

ACKNOWLEDGEMENT

Individuals such as Donnell Hewett, Dave Broyles, Lars Linde, Mike Robertson, Brad Kushner, Malcolm Jones, David Glover, Greg McNamee, Jan Alda, Alan Chuculate and Bill Moyes have also offered specific information either through their writing or by personal communication.

Gregg McNamee - 1996/12

Common sense tells us that the last thing we want to do in an emergency situation is give up control of the glider in order to terminate the tow.
If your system requires you to take your hand off the control bar to actuate the release it is not suitable.

http://ozreport.com/forum/viewtopic.php?t=1143
Death at Tocumwal

Davis Straub - 2006/01/24 12:27:32 UTC

Bill Moyes argues that you should not have to move your hand from the base bar to release.

Funny how these positions from THESE authorities never made it into any of Dennis's moronic fuckin' books.

The release I was referring to is the aerotow release primary:
http://www.blueskyhg.com/products.aspx?Prod=5&Manu=0
I also mentioned that I have not flown with a pro-tow. Please explain your point that a pro-tow is as safe as a two point tow release.

Why should Davis waste time EXPLAINING things when he can just PROCLAIM them?

Davis Straub - 2011/06/16 12:22:26 UTC

Incorrect in that the bar doesn't trim any further aft than when the tow force is split to the keel, or incorrect in that this doesn't limit pitch authority?

Both.

There you go. See, Zack?

Davis Straub - 2011/06/16 12:31:33 UTC

http://www.blueskyhg.com/products.aspx?Prod=5&Manu=0

There are many types of aerotow releases (as you can see from this discussion).

And one doesn't suck any more than another - just matters of preferences, opinions, and style.

The one you refer to is one type.

And a math genius as well. If he referred to two how many types would that be? (Take as much time as you need.)

That was told to me by Malcolm Jones...

Well, that may be his opinion, but it is nothing more than that.

Right. Everything in hang gliding is just a matter of opinion. Nothing is measurable, quantifiable, verifiable.

Protow requires more experience and skill and you certainly wouldn't use it as the first method for a new aerotow pilots, but is not less safe (nothing in hang gliding is safe) than the two point method.

Goddam right nothing in hang gliding is safe - mostly thanks to assholes like you.

Casey Cox - 2011/06/16 12:44:32 UTC

I'm not taking up for Malcolm, but now it's your opinion against his. Then you say it takes more skill. To me that is not as safe...my bad...I should have said takes more skill. I do not know Fawkes skill level and I thought it would be safer to suggest a 2 point release vice a shoulder release.

Yeah Ann, what's your skill level? How many times have you watched "The Incredibles"? Can you do the Elastigirl thing with your arms yet? How many inches?

You are right about releases being called different. Moyes calls the pro-tow (shoulder release) and Areotow release, simply (tow release).
http://www.moyes.com.au/accessories/various/tow-release.html

Yeah, just like angle of attack and pitch attitude, tension and pressure. Just different terms for the same things.

winDfried - 2011/06/16 12:51:32 UTC
Germany

Ha, a collision between the European and Anglo-Saxonian towing subcultures here.
Fawkes,
Being in Europe you'd better go with something well established and certified...

1. Yeah, like well established Bent Pin and Wallaby releases.
2. Certified by whom and using what criteria?

This barrel release is as good for static winch tow as it is for aero tow.
http://www.linkingwings.de/shop/link2/link2.html
Klinke Schleppklinke
http://www.linkingwings.de/shop/link2/files/BIGpage49_1.jpg

1. That's not a barrel release - that's a two stage.
2. A beach umbrella is as good for BASE jumping as it is for skydiving.

One of this kind cracked me a rib last year, when I belly landed on the runway after an early weak link break.

(Hurted a lot, but didn't keep me from flying. Luckily. Don't know how it interacts with a female anatomy?)
I reported the incident and it was published in the DHV-Info.

Damn. Now we have an incident in which somebody DID get hurt by plopping in on one of these things. So now the rabble can - and will - forever jump all over this one while ignoring the shattering of Holly's face and the pulping of Robin's head.

And, of course the issue that if the goddam DHV assholes recognized that weak links need to be mandated for 1.3 to 2.0 Gs that this would never have become a data point.

That's why I use this more convenient and very reliable one for aerotow:
http://www.drachenfliegenlernen.de/shop/schleppzubehoer/ulflash1schleppklinke.php

Andreas Ernst Becker - 2005/06/28 21:40:24 UTC

Hi Tad,

last weekend a pilot had a release with the Flash1 in 4m altitude, just short after take off. He could't manage to get up on his feet and broke an upright (no inruries).

Investigations are running, perhaps the release is too weak, or comes too fast. That's the reason why I won't ship you the Flash 1. You should get a fully functionable towing release.

That's OK, Andreas. I always HAD a fully functional towing release. (If you want something done right then do it yourself.)

Kevin Carter - 2006/02/19 09:54:30 UTC

I tried some euro push/pull releases that were total trash a few months ago.

Dangerous piece o' crap.

Both are fine, unless you try to aerotow with a (slow) single sail or low level intermediate behind a highly powered trike.
In this configuration you truly would need two point, with a second line split to the keel of your glider, as others have described in this thread.
I also figured, I will need to buy another system, when in need to use own weaklinks as it is apparently common in Australia.

http://ozreport.com/13.238
Adam Parer on his tuck and tumble

Adam Parer - 2009/11/25

Airborne 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.

Yeah. Good move, winDfried. Plenty more ribs where that one came from.

(The weaklink in German flightparks is 1.5 meters away from the pilot in the tow rope.)

How many Gs?

I still have the barrel thing for static winch tow, though.

Good luck.

Get up, have fun, W.

Good luck.

Davis Straub - 2011/06/16 13:13:49 UTC

To me that is not as safe...my bad...I should have said takes more skill.

Now we are in agreement.

Yeah, like a standup landing is just as safe as rolling it in on the wheels - just takes more skill. (Right, Sparky?)

Davis Straub - 2011/06/16 13:16:57 UTC

None of this is certified in the US.

Lucky for you, motherfucker.

Hang gliding is inherently unsafe.

Yeah, thanks.

Carole Sherrington (psuguru) - 2011/06/16 13:27:04 UTC
South Woodham Ferrers, Chelmsford, Essex

Re: Go DHV certified

Oi!
Don't go calling Americanos, "Anglo-Saxon". Living in the county of the East Saxons, I can tell the difference.

I believe Ann's desire is to have a tow-bridle attached to the glider as well as the shoulders. We call the arrangement she showed "a 3-ring circus". The Koch-alike 2-lever releases are well suited to static tow-lines where you have one bridle above and one below the control bar. With a Funky, she probably would do better when aerotowing with an attachment at the hang-point too.

There's a simple and effective release that paragliders use based on a Wichard spinnaker snap-shackle, although I've used them on boats and don't like them IN THAT APPLICATION because sails can generate so much force, you can't get them to open.

Whereas in hang gliding applications...

Ralph Sickinger - 2000/08/26 22:18:20 UTC

After towing to altitude, Sunny waved me off; I pulled on the release (hard), but nothing happened! After the second failed attempt to release, I thought about releasing from the secondary, but before I could move my hand the tug stalled and started to fall; Sunny had no choice but to gun the engine in attempt to regain flying speed, but this resulted in a sudden and severe pull on the harness and glider; I was only able to pull on the release again, while simultaneously praying for the weak link to break. The release finally opened, and I was free of the tug.

...it's simply not a problem.

http://www.wingsandsails.com/products/

Davis Straub - 2011/06/16 13:38:43 UTC

According to the video Fawkes is protowing. Any of these protow releases/bridles will work.

---
Photos of:
-


Piece o' shit Davis Bent Pin Release with squashed barrel, no weak link, and long skinny bridle that fails over half the time in lockout drills.
-


Tolerable three-string release and bridle.
-


Unbelievably stupid paraglider release with towline directly engaging spinnaker shackle at bridle apex.
-
http://www.moyes.com.au/images/virtuemart/product/barrel_release.jpg


Standard (bent pin) Bailey Release with no weak link and overlength bridle (like the one that killed Shane Smith at the beginning of the year).
-


DHV certified piece o' shit Flash 1 push/pull that Andreas won't sell me 'cause it's too dangerous.
---
Yeah Davis, as was just demonstrated at Jockey's Ridge last month, flying with your hang strap velcroed to your keel WILL work. Does that make it a great idea? Can you visualize any circumstances in which it might NOT work?

The problem with everything in those photos save for the three-string is that it will also FAIL. And if you want to look at THESE issues...

http://ozreport.com/12.084
The aerotowing accident a while back at Tocumwal

Davis Straub - 2008/04/28 14:24:19 UTC

The Windtech aerotow release is a "three ring" circle with the straps tied to your shoulder tabs and a short string to the "three ring" release. The issues with it are:

1. You have to take your hand off the base bar to grab the string.

2. The string is hard to find being thin, and next to the straps.

3. The three ring circle may not release with a pull on the string if there is no tension other than the weight of the rope on it. If the rope is bowed (which apparently was the case before the accident) then the release may not release.

...which you do when SOMEBODY ELSE'S junk is involved in a fatality, then they ALL "stink on ice".

Zack C - 2011/06/16 14:07:23 UTC

Both.

Really? I thought the bar being further back was well understood and documented.

And, in hang gliding, that's supposed to matter?

Two questions... How much airtime:
- do YOU have?
- does DAVIS have?

For example, this is from Wills Wing's site:

Towing from only the shoulder attachments without a top release is generally referred to as "Pro tow". The Sport 2, U2s and Talons may be "Pro towed" without a top release, however this method is not as easy as using a two point release as described above. Towing without a top release will cause the base tube to be positioned much further back during tow, the glider will have increased pitch pressure, and lockouts are much more difficult to correct.

(My emphasis. I would guess the statement about lockouts is due to the possible roll authority limitation I previously mentioned.)
I'm just pointing out the disagreement...I don't know who's right.

When your choices are:
- a) Davis
- b) somebody else
it's hard to go wrong with "b".

The next time I aerotow I'll try towing both ways and take some downtube video to compare.

FINALLY!

Unlike the relative safety of 'pro towing', the bar position issue isn't a matter of opinion.

Neither is the relative safety of 'pro towing'. More required control effort, less available speed range - thinner safety margin. PERIOD. Doesn't matter what you're flying, driving, pedaling, sailing, rowing, or paddling.

Davis Straub - 2011/06/16 14:29:59 UTC

I don't recall my bar position moving at all with either method.

The shit you don't recall would fill an encyclopedia.

So we have a disagreement about the facts of the matter.

Then do what you always do - make them up as you go along and ignore, block, and delete the ones you don't like.

I recall determining the bar position myself (as always).
There is significantly less bar pressure with the 2 point method (if you put the keel connection in the correct location).
Perhaps Wills Wing means the bar position (with the pilot's hands off) would change between the two methods.

Here... Lemme tell ya what Wills Wing means:

The Sport 2, U2s and Talons may be "Pro towed" without a top release, however this method is not as easy as using a two point release as described above. TOWING WITHOUT A TOP RELEASE WILL CAUSE THE BASE TUBE TO BE POSITIONED MUCH FURTHER BACK DURING TOW, the glider will have increased pitch pressure, and lockouts are much more difficult to correct.

Zack's emphasis - since you seem to be a bit slooooow on the uptake.

But I tow with my hands on the base tube.

http://ozreport.com/pub/fingerlakesaccident.shtml



Yeah Davis. And note that you also CRASH with your hands on the basetube.

Davis Straub - 2011/06/16 14:33:02 UTC

I think that they mean that you will have to pull in a lot harder (and more) with a protow setup.

Jim Gaar - 2011/06/16 14:58:52 UTC

Check out the launch position with pro tow

Davis here you are at the MWC's...

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winDfried - 2011/06/16 15:09:02 UTC

None of this is certified in the US. Hang gliding is inherently unsafe.

Allright, BUT
as an international hanggliding journalist...

Yeah, right. Facts selected, ignored, distorted, buried, blocked, deleted for your reading pleasure.

Your for sure know that in Germany every safety relvant peace of equipment needs to be

Certified?

, to be in use legally for us Trizonesians.

Yeah! DHV RULES! No weak links more dangerous than 130 kg. And if you wanna go even safer - sixty, thirty, whatever. No problem.

Exemption: visiting pilots.
As Fawkes apparently is residing for longer, it might hit her.
I don't know if she is located in Switzerland or Germany, maybe both.

Out of these nice peaces of equipment You have pictured here

http://www.hanggliding.org/viewtopic.php?t=22233&postdays=0&postorder=asc&start=20

I know only the for the last one positively that it is.
to be found here

http://www.dhv.de/DHVonlineDB/source/technicdatareport7.php?lang=DE&equptype=7&templatesetid=-1&idtype=3997&nopr=

Certificate Number "DHV 06-0033-04"

q.e.d. W.

BTW: Searchable tech database on certified equipment (in english) here:

http://www.dhv.de/DHVonlineDB/source/technicsearchpage.php?lang=EN

Casey Cox - 2011/06/16 15:49:40 UTC

Fawkes, I don't understand then why you dont get the same as other pilots in your area.

Sure Ann, if other pilots are doing something in your area it's just GOTTA be right.
You ever wonder why, in hang gliding but not sailplaning, different equipment is used in different areas?

Zack C - 2011/06/16 15:58:56 UTC

I think that they mean that you will have to pull in a lot harder (and more) with a protow setup.

Regardless of trim position, if you have to pull in more, doesn't that limit the amount you can pull in further?

Sounds to me like it would just make the tow safer... Less likely to dive into the ground or get into high speed oscillations.

Carole Sherrington - 2011/06/16 16:19:38 UTC

Found it!
Ann,
You can obtain the release in the UK from "The Loft" in Sussex.
http://www.theloftworkshop.co.uk/productpage.html
The local club uses The Loft for many a repair or re-pack and their work is of the highest quality.

bisleybob - 2011/06/16 16:22:23 UTC
Norfolk

zack i sense you are after information as you may be faced with changing at some point from one to the other.

its no big deal ive aerotowed/towed both ways. having a line on the glider just saves the arms of pilots with single surface gliders being pulled behind fast tugs. faster glider or slower tug then its less needed.

45mph behind a quantum on a target at 10 mins in your arms are pounding. but seriously control is not an issue. and believe me you can PIO just as bad with the line on the glider lol.

Yes. You CAN. Kinda like you CAN drive into a telephone pole at sixty miles per hour when you're stone cold sober on a sunny afternoon just as hard as you can when you're drunk as a skunk at midnight in an ice storm.

HOWEVER...

Since Pilot Induced Oscillations are Induced by Pilots, Pilots with ALL of the tow tension routed through them are a helluva lot more LIKELY to Induce them than Pilots with only HALF the tow tension routed through them.

But don't take MY word for it - talk to Holly.

Oh, right. The impact kinda took out her memory of the tow. Talk to someone who was watching Holly.

to add to debate i have flown with a Koch for 3 years and often crashed on it, ask PUD he has seen me land on my koch and i even bent it once and i didnt feel it at all. but when i press the button them lines are gone no questions.

Excuse me, I actually DO have a question...
Does the glider always continue doing what you want it to while you're pressing the button?

if you ever see how fast it can go wrong you dont want a faffy release my 2c

bisleybob - 2011/06/16 16:38:39 UTC

it goes wrong this quick

http://www.youtube.com/watch?v=HaSK4YJkIlM

Tigouille - 2011/06/16 20:39:51 UTC
Limoges

koch or barrel is ok
not the three rings which came from parachutes
a wichard you might have to shake to release without tension, therefore not so good.
Seconds can be important...

Seconds? Plural?

Mike Lake - 2011/06/16 21:16:36 UTC

Two point towing (pilot + glider) is different from one point (pilot only) in that a two point tow can offer assistance with both pitch and yaw, so it could be said that two point (being easier on the pilot) is safer than one point. I don't think that statement is stretching the imagination too much.
I think this is why the term 'pro tow' was adopted...

The term "pro tow" was adopted to create the illusion that skill and experience could somehow be counted on to compensate for the decertification of the glider. Analogous to telling people that a three quarter G weak link will compensate for a shitrigged release.

...you need to be a bit more of an active (pro?) pilot.

I'd argue that - for the most part - you need to be a LESS active pilot.

So two point safer then one point? Yes.

OF COURSE NOT!!! Davis doesn't sell a two point release. Don't ya think if a two point release made things safer then Davis would be selling one?

In reality one point works just fine and despite the fact that this method violates so comprehensively one of the keystones of that holy grail of towing 'The Skyting Criteria' the disasters predicted never materialised.

Yeah. That's 'cause the "physics" to back them up never materialized.

A one point can also dispense with additional hardware/rings/rope reducing the real world issues of a line snag...

You can - if you're not Davis - totally eliminate the issue of line snag...

...and getting a face full of metal.

...but I suspect the only way you can get a face full of metal is to use elastic material for your bridle(s).

So in that instance two point is safer then one point? No.

C'mon Mike... It's gonna end up being whatever Davis feels like saying it is. Why bother?

To ordinary recreational pilots the only thing that really matters is ...
Can I release in the shortest possible time in an emergency and not have to play "chase the release activator"?

Actually...

During a fast tow, I noticed I was getting out of alignment, but I was able to come back to it. The second time it happen I saw the tug line 45 degrees off to the left and was not able to align the glider again I tried to release but my body was off centered and could not reach the release. I kept trying and was close to 90 deg.

After watching this kinda bullshit for twenty years I'd hafta conclude that there is ABSOLUTELY NOTHING that matters to the ordinary recreational pilots or the assholes who "train" and "equip" them.

Is the release going to work when I need it to and also not dump me at 50 feet?

Jeesh Mike! If those were REAL issues why would people fly with Davis Releases and 130 pound Greenspot weak links?

After release is there any likelihood of anything else snagging or binding the line?

http://www.youtube.com/watch?v=SGPZkrf94D4

Do I run the risk of getting my teeth knocked out if a line breaks under tension?
Anything else by comparison is just white noise.

Mike Lake - 2011/06/16 22:17:21 UTC

An example of a system that could easily end in disaster.
Does anyone think this OK.

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Yeah, Head Trauma... Do you think that's OK?

Davis Straub - 2011/06/17 00:08:12 UTC

Regardless of trim position, if you have to pull in more, doesn't that limit the amount you can pull in further?

Not that I ever noticed.
This all seems to be irrelevant. I have had many hundreds of aerotows with and without protows. It's not an issue.

Oh. So if not anything that YOU ever NOTICE and/or SEEMS to be relevant and YOU have had HUNDREDS of tows without getting killed it's perfectly OK if somebody else does once every ten years or so.

Yeah, big surprise.

Davis Straub - 2011/06/17 00:11:33 UTC

Davis here you are at the MWC's

Thanks.
Don't seem to have to pull in too much.

Davis Straub - 2011/06/17 00:15:00 UTC

For a report on when the 3-ring circus fails:
http://ozreport.com/toc.php?12.084#1

That's odd. 'Cause the first thing you say is:

Why do I consider the 300' tow rope the proximate cause of the accident?

Because if the rope had been 150' the pilot would be alive today.

If you generate enough slack between yourself and the tug to allow the end of the towline to tie itself to your sidewire I'm not seeing that it makes much difference what the hell you're using for a release.

But as long as we're on the subject of equipment failures...

Quallaby Release:
1999/02/27 - Rob Richardson
2006/02/05 - John Dullahan
2004/06/26 - Mike Haas
2005/01/09 - Robin Strid
2008/03/23 - Lauren Tjaden
2008/06/02 - Carlos Weill

Lookout Release:
2000/08/26 - Ralph Sickinger
2009/08/31 - Roy Messing
2010/11/24 - Zack C

Davis Release:
0000/00/00 - Dennis Pagen
2004/08/02 - Davis Straub
2005/05/29 - Holly Korzilius
2008/03/23 - Lauren Tjaden
2009/01/03 - Stephen Elliot
2011/02/25 - Bart Weghorst

Steve Wendt Truck Tow Release:
37 - 1990/03/29 - Brad Anderson
38 - 1990/07/05 - Eric Aasletten

Bobby Weak Link:
1996/07/25 - Bill Bennett / Mike Del Signore
2005/09/03 - Arlan Birkett / Jeremiah Thompson

Davis Weak Link
0000/00/00 - Shane Nestle
2005/01/13 - Tom Lanning
2008/05/18 - Socrates Zayas
2009/01/06 - Trent Brown
2011/06/17 - winDfried

Davis Straub - 2011/06/17 00:24:31 UTC

...you for sure know that in Germany every safety relevant peace of equipment needs to be certified...

I, for sure, don't know that. I haven't flown in Germany since I took my very first flight (and the one time I flew the ATOS near Stuttgart). Hasn't been in issue in Austria, Switzerland, Italy, or France.

Hard to tell what actual releases are on the DHV site as it's hard to find the pictures.

I've been reporting on releases for years and years.

Sure ya have, Davis.

http://ozreport.com/forum/viewtopic.php?t=22660
What can be learned from this "scooter" towing accident?

Davis Straub - 2011/02/07 19:21:29 UTC

Okay, enough. On to new threads.

That's why they just keep getting better and better year after year.

But most of them are produced in the US...

PRODUCED? Isn't that a rather dignified term for shoving a bent pin into a chunk of tubing?

...and I have little knowledge of what is used in Germany. I had a Koch, but never used it and certainly wouldn't use it for aerotowing.

http://www.hanggliding.org/viewtopic.php?t=21033
barrels release without any tension except weight of rope..

Bart Weghorst - 2011/02/25 19:06:26 UTC

I've had it once where the pin had bent inside the barrel from excessive tow force. My weaklink was still intact. The tug pilot's weaklink broke so I had the rope. I had to use two hands to get the pin out of the barrel.

Yeah Davis. And we all know what you WOULD use for aerotowing. The problem is that you're also selling it and OTHER people are in danger of getting killed too.

Zack C - 2011/06/17 02:49:08 UTC

Don't seem to have to pull in too much.

Here's me towing with a V bridle for comparison.

Just "a" V bridle? Hmmph.

Is the difference significant?

MOST of the time... No.

I don't know, but if I were to hit a strong thermal shortly after lifting off and go skyrocketing above the tug (I know of at least one fatality report that begins that way), I'd want all the pull-in ability I could get.

If you open it up to surface towing I can give you a couple more.

Davis Straub - 2011/06/17 03:42:00 UTC

Zack,
I suggest that you do what you are comfortable with.

Why, thank you, Davis.
Ya know... Everybody's always comfortable with everything. That's how come they never try to do better before they get killed on it.

I'm just suggesting that the issues that you raise are not an issue for anyone that I aerotow with in competition.

Yeah, but the people we REALLY need to be talking to are the ones who've died aerotowing with you in competition. But we can't. 'Cause they're dead.

Besides, they are beside the point of this thread.

Okay, enough. On to new threads.

Ann Fawkes - 2011/06/17 13:06:00 UTC

Wow, I am not watching for a while and this thread grew exponential
Going to take my time to read all through and make up my opinion ...

Oh good. You're gonna make up your OPINION based upon other people's OPINIONS. Glad we don't have a bunch of boring engineering standards to sort through.

Thanks for all the advise.

Davis Straub - 2011/06/17 13:18:34 UTC

Looks like your original question got answered with a link to where you can purchase your 3 ring circus.

Steve Kinsley - 1996/05/09 15:50

Personal opinion. While I don't know the circumstances of Frank's death and I am not an awesome tow type dude, I think tow releases, all of them, stink on ice. Reason: You need two hands to drive a hang glider. You 'specially need two hands if it starts to turn on tow. If you let go to release, the glider can almost instantly assume a radical attitude. We need a release that is held in the mouth. A clothespin. Open your mouth and you're off.

Yeah, we just never discussed anything that didn't stink on ice.

datum, data

ok ok, I am the latin fellow ! I thought americans would prefer a "s"..

2:1?

2 (pilot+glider) : 1 (microlight)

I received a part of the answer I asked:

Our tug release is an AIR CREATION U39302A




15daN actuation for a 160daN tow line tension

A tug of our club told me we change the systeme of release handle as we can actuate with less effort by hand or foot (but no objective data!)..

Barrel release - straight pin

I made one just to test it and found that the actuation was really hard at 50kg with a 2mm eye of bridlelink, cause of the friction of the barrel (6mm ID) with the leechline.




How do you manage this to have the good L/A ratio you said ?

Thanks