Releases

[Tad Eareckson]

What is your final OD : 10mm maybe.

10.2 maybe.

I will use a thick walled (+2.4mm) heat shrink 3:1 rather than the glue operation.. easier.

If it works - fine. That's the part of the construction I most dread. (There IS such a thing as heat shrink tubing with a glue coating inside but I can't get in in green (starboard) - only in red (port) - and I'm too anal to live with the cosmetic mismatched of materials.)

...why not to use a thinner tube ID 5mm ?

1. With what I'm using the pin is folded back and retained virtually parallel to the inside tubing walls.

http://www.flickr.com/photos/aerotowrelease/8306296899/


That vinyl tubing has an ID of 0.250 inches. The aluminum is 0.259. Good luck seeing or feeling a difference.

If the pin were folded back beyond parallel your performance would be degraded until the barrel was pulled all the way back to the tip.

And even if it isn't folded all the way to parallel... when the angle is shy a few degrees the difference is extremely negligible.

2. When you start approaching 400 pounds direct loading you risk damaging the pin if you're engaging anything thicker than the Yale Crystalyne I've got in:

http://www.flickr.com/photos/aerotowrelease/8311348069/


I can't find anything that thin that holds to that tension and they discontinued that diameter line.

3. So I don't recommend that that pin be loaded to over 350 pounds.

4. You can blow 350 pounds direct loading (700 pounds towline) with a seventeen pound pull. You can do that with your thumb and index finger.

5. You will NEVER - even without weak links - see anything close to that in real life.

Vectran seems to me a good idea as it slide better than the leechline in wrapped dyneema and is thick enough to stabilize the barrel with no load.

I would GUESS that you're not going to be able to detect a difference. We've already got massive overkill, but if you can do anything to improve performance - cool, I'm all for it. You might get something detectable by using stainless steel but I'm not sure it would be worth it. (The aluminum is cheap, light, and easy to work with.)

I'm not sure to be confortable with barrel shifted forward (required by the length of the bridlelink)...

1. The more you lengthen the Bridle Link the more you're introducing a possibility for full failure. (And if you're still alive after that I guarantee you'll wish you had releases on BOTH shoulders.)

2. I and others have flown with those proportions with fewer problems than the ubiquitous junk.

3. Out in front you know where they are because you can see them.

4. You can't tell how for away from your hand a barrel will be when you need it because you can't tell in advance where the basetube is going to be when you need to release.

However... You will not be using a barrel unless your two point bridle has wrapped at the tow ring or you're deliberately towing one point. So the bar IS likely to be back and the barrels WILL thus be farther away from them.

5. But why worry? The second you take your hand off the basetube you're probably gonna die anyway.

If you're using the barrel releases as secondaries in two point towing - what the hell - you're probably never going to need them because it's almost certain that the Bridle Link will blow. And you'll undoubtedly be at altitude anyway.

If you're regularly towing one point you are out of your mind not using one of the many cheap and easy bite controlled releases. The Russians have been using them since the dinosaurs roamed the Earth and there are a couple of good models in my photo set. One guy I was corresponding with - Craig Stanley - took the Four-String concept - invented by Steve Kinsley - and made himself a clunky but perfectly safe and functional unit with about five dollars worth of material from the hardware store.

The hand pulled barrel release is just fine for all circumstances you're likely to encounter but if you think it's going to be adequate for a low level emergency your chances of being killed on tow are up by a factor of at least twenty.

And I'll be more than happy to keep helping you with something bulletproof for one of your shoulders.

[deltaman]

I asked questions as it comes.

For our tandem bridle system..
I put a double loop of greenspot 130lb on the upper side: 120kg/1,15 * 2 = 209kg, and will install at the bottom a +20% wl: a bridlelink n°9 (147kg) (with 9 stitches and 3 on the other side). n°9 is right in this case?

Way to release a barrel:

3. Out in front you know where they are because you can see them.

for me no need to have an eye on the barrel itself, you already can see the bridle, just catch it and slide along.

Using a short bridle in a one point AT
A spliced braided bridle in which the two thinned ends overlap together. You can't see and feel the junction, it is thicker as well. +2 wl at both loops.

Did you see that ?
http://ozreport.com/overunder.php
I just want to point the idea to install a sort of primary release (why not a Joe street) on the harness loop with release handle on the basebar rather than a barrel. Which drawback except the fact that you are chained to your basebar.

I discovered that it exists different quality of curved pin material.

http://www.flickr.com/photos/psucvollibre/5898815966/


The 2 left ones, lighter alu, will bent at 100kg and break at 115kg on the bailey assembly. I didn't test the right one, seems to be the same type of metal than the straight pin. The straight pin bent was pushing at 130kg+ in the same bailey tubing ("wide"), the webbing blow.

[Tad Eareckson]

I put a double loop of greenspot 130lb on the upper side: 120kg...

Is that an assumed or tested value? I usually get around 92 kg for a double - much less than twice a single.

I'm not happy with multiple loops because they're less predictable than singles.

...for me no need to have an eye on the barrel itself...

Getting to these barrels - no matter how close in or far out they are - isn't a big problem. The big problem is having to let go of the basetube in an emergency.

A spliced braided bridle...

Your chances of having a problem with a good bridle in a high tension situation in which you're low enough that it matters are extremely low. But if my choices are zero or one in a million I'm going to take the former - if there are no tradeoffs or downsides.

Did you see that ?

No. Thanks.

I appreciate ANYONE who makes an effort to invent or improve something and I'd say that this system is probably a little safer than the Koch two stage but I'd still stay with the Koch. This arrangement is something of a mess and there's no guarantee that bridle is going to clear the loop. (And it's totally beyond me why hang glider pilots are so happy with rope on rope junctions sawing each other apart. You'd think that thimbles cost hundreds of dollars and presented choking hazards.)

The best way to address that issue is to develop or modify a Koch type design so that it can also be triggered by a lanyard in your teeth or electronically with a button in your hand and a wire running up your sleeve.

Which drawback except the fact that you are chained to your basebar.

For what kind of towing? If it's dolly or wheel launched aero it would be a stupid junky way to address the issues when there's vastly superior stuff available. That Four-String Release is a thing of beauty. The shoulder mounted Remote Barrel Release is fine as well. Even a twenty dollar Linknife with a string going to your teeth isn't bad.

I discovered that it exists different quality of curved pin material.

I so do wish Bobby had understood that a curved pin is a great idea for a parachute deployment component and a really crappy one for a lever.

The straight pin bent was pushing at 130kg+ in the same bailey tubing ("wide"), the webbing blow.

Steve Wendt and his adoring fans are idiots.

Thanks for the testing and documentation.

[deltaman]

Is that an assumed or tested value? I usually get around 92 kg for a double - much less than twice a single.
I'm not happy with multiple loops because they're less predictable than singles.

The way I tested first was 120kg: a double through a ring and in a quick link on the other side.
I just tested between a bridle loop (larkshead) and a barrel and found: 108 115 115 114 115 120kg

By the way I asked my tug to substitude his 2 loops of 95kg wl for a double one on the tug side as I thought it was more predictable than 2 loops shaped at a "quite" same size...

Steve Wendt

?

[Tad Eareckson]

...a double through a ring and in a quick link on the other side.

I would predict that that would give you higher and more consistent/predictable results because the loops are likely to be loaded pretty evenly.

108 115 115 114 115 120

Average of 114.5, varies by about five percent up or down. Not bad. BUT...

- I find I can do way better with single loops.

- It's theoretically possible for those double loops to seat perfectly evenly and get something WAY up from the average. That could be dangerous if you're trying to fine tune primary and secondary or front and back end weak links. And note that...

http://www.hanggliding.org/viewtopic.php?t=22428
tow release story

...one of your countrymen just burned up a landing field (literally) as a direct consequence of a weak link sequencing issue. Could have easily gotten killed too. Zero excuse for that kind of bullshit.

And less than six years ago here in the US we had a flight park operator kill his student along with himself in a tandem crash in no small part because the front end weak link wasn't up to snuff.

And I got real tired of those assholes at Ridgely towing me with a weak link way lighter than mine - sometimes lighter than the 130 pound Greenspot they were making everyone else use.

By the way I asked my tug to substitude his 2 loops of 95kg wl for a double one on the tug side as I thought it was more predictable than 2 loops shaped at a "quite" same size...

If you're worried about predictability... Use a Tost up front. Or use one of my Tow Line Shear Links:

http://www.flickr.com/photos/aerotowrelease/8313448914/


http://www.flickr.com/photos/aerotowrelease/8312399685/

Up front it doesn't get dragged and it's light, available in finer graduations, and pretty predictable up to about six hundred pounds.

Steve Wendt...

Former Kitty Hawk Kites manager - just after my time. (Previous couple of managers were douchebags too.) Now runs Blue Sky near Richmond.

Junk merchant. Sells bent pin releases and, starting recently, straight pins in fat barrels. Tells everybody that there's really no appreciable difference - just different "styles" of the same thing.

Got one of his students half killed by putting her up with a bent pin and no weak link and cutting her loose at the worst possible moment in an oscillation cycle. No interest whatsoever in any of my equipment or the multi-string bite controlled release that Steve Kinsley demoed down there about two and a half months before Holly got trashed. There's no doubt whatsoever that she'd have been fine if she had had one.

Got another student totally killed four months later 'cause he doesn't believe in adhering to USHGA regulations and teaching hook-in checks.

Signed Rooney off as an instructor right before he three quarters killed himself and almost barbecued his passenger in the powerlines (speaking of powerlines). Steve doesn't teach his instructors to adhere to hook-in check regulations either.

Tows people up on his platform rig with release lanyards on their wrists and expectations of the weak link blowing to protect them from lockouts.

Won't let you do mild aerobatics over his goddam flight park but has no problem whatsoever letting tandem gliders go up without wheels - which is how and where Greg DeWolf broke an arm.

Kicked me out of the clinic which would have been my first opportunity to aerotow - Gerard Thevenot introducing the Cosmos tug, 1984/02/11 - 'cause I had had cancer the previous year and he deemed me too weak to handle it. A week later I flew High Rock for over two and a half hours.

Fuckin' asshole. And, of course, HIGHLY regarded and respected in the US hang gliding community.

Reserve the right to amend as I remember more stuff.

[MikeLake]

It's not HIGH tension that tends to get planes - virtually always gliders - killed. It's MISALIGNED tension - and you can't defend against misaligned tension with a weak link because a hundred and fifty pounds of it can kill you just as dead as five hundred.

This hugely preeminent statement deserves highlighting.
Assuming tensions are below equipment breaking values the above four lines of text effectively ridicule the current thinking on weak-links.

ATTENTION anyone browsing this forum.
If you read nothing else read the above.

[Tad Eareckson]

Boy am I good at getting this concept through to people who've thoroughly understood it for the past third of a century anyway.

But...

Donnell Hewett - 1985/04

And concerning the three other USA fatalities - those involving beginner/novices and apparent lockouts - I would like to know what these inexperienced pilots were doing at altitudes high enough to lock out? Were they being pulled so fast that a lockout which started at only three to six feet forced them into an arc high enough to roll over? If so, why were they being pulled so fast? What strength of weak link were they using that it didn't break when being pulled that fast?

Jerry Forburger - 1990/10

High line tensions reduce the pilot's ability to control the glider and we all know that the killer "lockout" is caused by high towline tension.

Dennis Pagen - 1993/04

Jerry Forburger, ATOL designer and tow guru

Dennis Pagen / Bill Bryden - 1998/01

Fortunately, we have good defenses against lockouts. These defenses include limiting the tow forces by using weak links and pressure gauges...

...this is what we have in our newsletters, magazines, and textbooks. And who are we to argue with gurus - especially when everybody already knows this stuff?

Not to be overly critical, but...

http://www.hanggliding.org/viewtopic.php?t=22428
tow release story

pud - 2011/07/04 23:07:21 UTC

peanuts - 2011/07/04 14:00:43 UTC

...the one that is claimed to be 100% absolutely guaranteed completely perfect and impossible to have any malfunctions within 1000 meters of its location .

Yes indeed that's the one.

I thought you could've been WAY more sarcastic. That douchebag has never once in his miserable existence given a rat's ass about making statements of every level of stupidity imaginable.

I so do wish I knew his real identity. He goes back to the Seventies and is from my turf so I know I know him but he's always managed his cowardly anonymity really well.

P.S. Note HIS response to the three that followed his idiot post.
---
peanuts = Dennis Wood

[bobk]

Great Post:

It's not HIGH tension that tends to get planes - virtually always gliders - killed. It's MISALIGNED tension - and you can't defend against misaligned tension with a weak link because a hundred and fifty pounds of it can kill you just as dead as five hundred.

This hugely preeminent statement deserves highlighting.
Assuming tensions are below equipment breaking values the above four lines of text effectively ridicule the current thinking on weak-links.

ATTENTION anyone browsing this forum.
If you read nothing else read the above.

Thanks for highlighting that comment Mike. I'm still mostly a foot-launch pilot (only one tandem aerotow so far), but reading comments like these will be a big help as I hopefully start working on my tow ratings.

Thanks for drawing attention to this comment.

Bob Kuczewski

[Zack C]

So I took a trip to Lookout last weekend and my release gave me trouble (must be something in the air over there...). I took two tows on two different days and on both I had to pull the actuator loop three times before it released (password = 'red'):

http://vimeo.com/26212486


Naturally, the release worked fine on the ground. I brought the release to the shop for 'inspection' (following the manual's instructions...) and the employee there seemed concerned but not surprised...she said they modified the design since I purchased mine (I didn't follow her description of the change but I think she was saying they shortened the required travel distance of the barrel) and would swap my release for a new one at no charge.

I took them up on it...they only had one in stock and without a side-by-side comparison it appears the same to me. Shortly after I got it I noticed the barrel seemed fixed in place short of the pin...it wouldn't budge. The release was coiled into a helix secured by the Velcro straps. I unwound it and found it then functioned as expected, but coiling it again reduced the available travel distance of the barrel. I never noticed behavior like this with other releases and don't understand it but the fact that the curvature of the cable can apparently affect release performance greatly concerns me.

On top of that, after getting back to my glider I found the cable was much longer than my previous one. It looks like it was made for a tandem or something. By this point the shop was closed and I was heading out early the next day, so it looks like I'm just going to have to deal with the excess for now.

And if that wasn't enough, I talked to a pilot from NW Texas that was also visiting and he had problems with the barrel on his release being so close to the edge of the pin that it was releasing prematurely on him a few feet off the ground. Last I spoke with him Matt was working on fixing it.

Guess I can't trust even the 'best release on the market'. Time to contact Joe Street...

By the way, no one at Lookout said anything about my (your) equipment, although I think only the launch assistants got a good look at it.

I had hoped to ask Steve Pearson his thoughts on building releases into gliders (he was there for Demo Days), but I didn't get a chance to talk to him.

Zack

[bobk]

Thanks for that post Zack. It's a real eye opener.