Tad's Barrel Release and maybe an alternative

[hefalump]

I'm probably going to regret this but here goes.

Tad,

I took a look at your picture page to look at your barrel release. I have to admit that with straight pins and with the eye of the pin in a snug rope loop it does seem to be impossible to rig it backwards as you can with the curved pins and webbing (as how I did).

But I have concerns with the relative size of the rope and pins eye (big eye, thin rope). In one photo you show the release properly rigged capturing a piece of weak link attached to the bridle. It looks pretty good under tension with each side of the weak link loop passing either side of the steel pin's eye. But if you let the assembly go slack as so far as the weak link forms a sag, it is very easy to catch both sides of the weak link on one side of the pin's eye when tension is reapplied, try it, I just did.

The result is exactly the picture you show of your barrel release miss-assembled. Of course the smaller the weak link the less likely this is to happen, but it has to be very small, just enough weak link loop for the pin to pass through.

Having the tow bridle go slack enough to create this problem is a very real possibility, walking the cart to launch, going prone just before launch, ect.

The Bailey, although it can be rigged backwards by an inattentive pilot, does have an advantage with this respect. Once rigged properly the barrel is slid up over the eye where both the top and the bottom of the pin's eye contact the barrel keeping both sides of weak link on their respective sides of the eye.

Your design could benefit from an over the eye sliding barrel as well.

I was thinking, it would be nice to completely remove the "eye" problem. I was thinking about a "Folded Pin" design. Basically a length of cable with the last one inch (or so) tinned to make it stiff, leave the next inch (or so) un-tinned and flexible, then another inch (or so) tinned, then finally to a loop or other attachment point to the harness. Now the way it would work is similar to the pin and barrel except you would bend the flex part of the cable back onto itself, capturing the weak link, with the two stiff sections parallel to each other, then slide the barrel over the stiff sections.

When the barrel is slide back the cable springs straight and dumps the weak link ... no snags ... no muss.

Of course I will still have to work out the best proportions of flex to stiff sections as well as barrel travel limits to make it work right.

Ideally stainless cable would be best for obvious reasons, however, stainless does not tin very well. I could use a different material or possibly TIG weld the stainless cable to make it stiff or weld sleeves over the cable for straight sections and grind the welds smooth.

It will probably put a hell of a kink in the cable but we only need a fraction of the cable's ultimate strength and fatigue only really occures if you try to straighten, kink, straighten, kink and so on. When it releases the weak link it will never really straighten out and the user would just leave it kinked.

I could also try other materials less prone to kinking like synthetic ropes with heat fused rigid straight sections.

I'll try to work up some proto types when I get back from Germany some time in April.

Don't get me wrong I still like the Bailey design and it still may be, at least for me, the best design. But if there are other possibilities we might as well flesh them out.

Am I helping now?

JD

[jimrooney]

Here we go, reinventing the wheel again.

Couple erroneous conclusions....
A Bailey release can not be rigged incorrectly. Yours was either a bad copy or an incomplete/defective release. A proper Bailey release has a rivot stop in it that prevents it from being rigged wrong. Yours did not have this.

After arguing this with Tadd, he eventually "fixed" the same "problem" with his barrel release... a "problem" that was already "fixed" in with the Bailey release. Before he added the stop, you could rig his the same way.

So....
Why are we reinventing the wheel again?
What advantage does a straight pin have over a curved pin?

Jim

[Matthew]

Jim,

Any chance we can test out Tad's and other releases at the Highland Fly-In this year. I propose that we put Tad in a little red wagon right next to the swamp and then run a rope to the other end of the swamp. We hook Tad up to the various releases and then have a group of volunteers (I'm sure we can get plenty) pull the rope and Tad towards the swamp. If the release works well, Tad stays dry. If the release fails or is slow, Tad is in the swamp and he gets a Tad wet and a Tad muddy. Well, maybe more than a Tad.

What'cha think?

Tad-Pull Tad-Pull Tad-Pull!!!

You could sell T-shirts too.....

Matthew

[Tad Eareckson]

Following is a copy of probably all of the correspondence in this topic that was lost as a result of the server crash. Times are Greenwich. Ticker counts, where available, appear following the posts.
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jimrooney

2008/02/12 03:49:57

Hrm... could be on to something there.
Might need some flushing out (er fleshing out), but the premise seems solid enough ;)

Jim
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Tad Eareckson

2008/02/13 00:22:39

Matthew,

Nah, I've got no interest in getting a face full of leeches 'cause someone else's crap did what I predicted.

But I'm not at all opposed to a more refined version of the concept.

I just caught Rebel Without A Cause for the first time a three weekends ago and saw a much better basic format for that sort of thing.

First, let's make teamsIcallSteveKinsley.

Mousetrap and Squid versus the Alligators: Wallaby and Quest.

Each round, two gliders - one from each team, both kites on carts with our normal weapons.

Trucks with bumper hitches on the other end of the tow lines.

Tow gliders abreast to 20 mph airspeed, cameras rolling.

Cannon fires, last glider to dump tension hands C note to first.

Rules:

You come off the cart or dump tension for any reason - including weak link break - prior to the puff - you lose.

Matched two and one point rounds - I get to fly in both categories.

No Lookouts or Hinkels - they might tie us.

No brake levers on basetubes - too dangerous and they might tie us.

So any of you other punks feelin' lucky?

But back to business at hand...

JD,

First off - Whoa! What a fast, dramatic, and pleasantly surprising shift from never question authority mode to thinking for yourself and coming up with an original idea (which, unfortunately, I plan on hacking up a bit - but what the hell - excellent direction).

Anyway...

I don't do opinion without identifying it as such. I'm more of a numbers person. You beat my numbers - I'm yours.

I really wasn't intending to make a personal attack. I apologize though, if I left that impression. But I'm an equal opportunity hatchet man. I kick myself in the ass as hard as possible whenever I screw the pooch - which is quite often enough.

But I've been smoldering for a long time over this phenomenon of increasing the complexity and expense while decreasing the performance and safety margin of a piece of equipment 'cause someone might go out of his way to find a way to kill himself with the better option. I'm only interested in designing for someone who can bother to Read The Fuckin' Manual before accepting the responsibility of dangling his ass a mile up in the breeze.

Case in point - If you give me three bucks of material - a straight parachute pin, 430 millimeters of eighth inch leechline, and four inches of beveled 3/8 inch aluminum tubing - and about forty seconds I can make you a better, safer barrel release than virtually anyone else in the world is using. If you over rotate the pin you can get it to hesitate a tiny bit under near slack line tension - a virtual non issue - and with a bit of effort it can be locked - as in the photo - but as you said with respect to a very similar matter and we agree:

>
I don't think that anyone capable of doing this should be flying.
<

I'm not saying you're a poor pilot - you may be well be able to / probably can kick my ass ten out of ten out of ten days at Ridgely. But I am saying this has NOTHING NAUGHT NIL ZILCH ZERO NADA to do with flying.

And I'm not saying that what you did was stupid (well, yeah, I did kinda imply that). But I do find it incredibly counterintuitive and I still would really like to know why it happened. Come on - I just 'fessed up (again) to carrying a glider to launch minus a pin at the starboard downtube/basetube junction. Let us know what you were thinking so the rest of us can learn from your mistake too.

Stepping off a cliff with a carabiner dangling behind one's legs does not mean one is a poor pilot, stupid, or lacking in intuition. It just means one is human. I'm just trying to find ways to compensate for that.

No, nobody walks on water, not Bobby or Steve Pearson or yours truly - but our designs can. If the Wills Wing folk all walked on water their first glider would have been a T3. Hang gliders have evolved, leveled out at a few plateaus along the way, and are probably now at the performance limits of what can be still be defined as something of a bird of that feather without pouring in many more buckets of money.

Yeah, my release system is 100% effective. Like the T3 it is the result of many years of major revisions, tweaking, and rethinking concepts. But a release system is a lot simpler than any glider it's going to go on and it's a whole lot easier to push the performance limits to the wall. You do your job, it'll do its. Curved pin barrel (Bailey) releases are also - as far as I've heard - 100% effective (but they're still pieces of crap). A few other devices in the totally reliable category - multi-string releases (properly constructed), Linknives, Tost sailplane releases.

Let's not do "SEEM to claim" - let's stick to things I actually say.

And, oops, I just checked back and found an instance in which I did plagiarize somebody. Instead of "my stuff" I should have said "my and/or Steve's stuff" - the multi-string is his.

Let's take a look at Robin. He didn't freeze. He actuated the release. The spinnaker shackle opened. But the weak link locked on the gate and he was dead a few seconds later.

My remote barrel release didn't exist at that point. I developed it as a response to that accident. That kind of malfunction is absolutely impossible to duplicate on the revision.

You wanna talk CALLOUS? Callous is seeing that happen and not doing anything about it while waiting around for the next head to get smashed.

And, by the way - I'm not "out peddling my wares". I've put enormous time and effort and a lot of bucks into these technologies and more of the same into documentation and have offered it for free. I've given a lot of stuff away for free. Once in three or four blue moons I'll sell something for the cost of materials and about twenty cents an hour labor and half the time people never seem to get back to me to actually pay for the stuff and I can name one coauthor of Towing Aloft who tells me he won't stiff me - but the better part of two years later...

You mention that releases are useless until pilots actuate them and sometimes they freeze (and sometimes they miss). Don't you find that disturbingly inconsistent with your earlier statement that:

>
I see no problem in the way things are currently done and creating overly complicated mouth actuated releases is just a waste of time.
<

Contrast to this from back in the USSR (Oz Report Forum) regarding an analogous predecessor:

>
I have no idea why pilots in other countries do not use it. Can't imagine learning to tow with anything else.

Sergey Marin
<

With respect to ascertaining reliability...

What possible bearing could the number of people using my release system (one) or the number of times I tow per year (three) have on determining its effectiveness? Only a total idiot works this way.

When Wills Wing certifies a glider they don't just throw it into the air and see what happens. They strap it down to a truck with a thirty thousand horsepower engine and brutalize the hell out of it. Then somebody clips in and checks the minor variations in the basic flight characteristics they know they're gonna have.

Release systems have NOTHING to do with flying. The USHGA Release Test Procedures I mentioned earlier make no mention of it because aerodynamics are not involved. Release systems hold and dump loads. PERIOD. I subject mine to abuse on the ground that would kill your glider - not to mention the releases YOU use - if you tried to duplicate it in the air. That's how engineers work.

With respect to your questions on redundancy...

I fly with a weak link in the middle of the USHGA Aerotowing Guidelines range (1.4 Gs - 522 pounds tow line tension) for the following reasons...

1. If anything really really bad and unpredictable happens - like a Cessna flying between me and the tug - the weak link will break before the glider does. I need and use it at the same frequency as I do my parachute.

2. The aforementioned Guidelines require me to do so.

3. There is no reason NOT to use it. It will never break in a manner which compromises my safety and convenience.

Since I am using a two point opening bridle there is no absolute guarantee that its end will clear the tow carabiner. While even though the construction of my bridle makes the likelihood of a wrap a virtual impossibility, I nevertheless have an autorelease feature at the bottom end.

My secondary bridle is also a secondary weak link. Therefore I am immediately and fully prepared to switch to one point mode (as Holly wasn't).

I have a barrel release on the port side in case the autorelease doesn't kick in and for use in one point mode and I have a dead man switch on the starboard in case I ever really need to get off the line in a hurry and I'm really busy flying the glider.

But listen good to this last part...

THERE IS NO DOWNSIDE TO HAVING ANY OF THIS REDUNDANCY. There is no reason NOT to have it. It can't cause any problems. None of it weighs any more than the line it replaces (practically speaking) and it all gets stowed as soon as I get a free moment. I'm still lighter and cleaner than ANY of my counterparts.

You like backups. I like backups - as long they can be of some conceivable use and they don't cost me anything. I'd like to have a Plan C with which to busy myself after my parachute has been eaten by my wreckage but I don't have a lot of great ideas for that one.

Let's make this interesting... Five hundred bucks says neither you nor anybody else can simulate anything that doesn't involve meteorites or loose tail rotors that keeps me under tension for two seconds from the gun.

No, I didn't think so.

OK. On to your alternative stuff...

Thank you for taking a look at the photos. If you keep doing that and thinking, talking, and listening you're gonna realize that my system is actually a lot less complicated than you thought, a lot less so, in fact, than the spinnaker shackle / curved pin crap that's currently clogging the flight parks. You're gonna become less and less motivated to risk those five C notes.

I'm not entirely sure that you fully understand why the illustrated barrel releases can't be sabotaged however.

The leechline bodies/bases (analogous to your webbing) of all variations are unified. Each is fully stitched along its entire length between the pin and the aft eye by which it is attached. There are no split elements through which the pin can be rotated. In basic principle this is not necessary but some of the stitching strengthens the unit and things are a bit neater (and, for what it's worth, more idiot resistant) that way.

Also in basic principle - as in the forty second miracle version described above - with a straight pin there is no such thing as backwards. As long as you don't flip rather than rotate the pin it's impossible to screw up.

I've experimented with this before and I did again upon reading your post. You may have been able to manipulate an oversized slack Greenspot weak link (or any other loop of string) such that you got both runs on the same side of the eye but NOT in the configuration illustrating the misconnection and lock.

You did not say that the configuration you induced hindered the operation of that release in any way. Once that pin engages a loop and is rotated (rather than flipped) back there is no freakin' way that release can be disabled.

In death mode the loop lassos the base - the runs are on opposite sides of the base and, consequently, on the same side of the eye. In the harmless configuration you discovered the runs are on the same side of the base and, as long as that is the case, it doesn't matter which side(s) of the eye they contact.

Thus the large diameter barrel incorporated - by necessity - in the the curved pin release and which you propose as a modification for my straight pin release puts us back (again) in Paragraph 6 mode:

>
You have invented a solution for a problem that doesn't exist.
<

and makes my configuration weaker, less efficient, and more dangerous.

In any case - an oversized weak link is not a component of my system. My documentation defines precise specifications for the various weak links in the configuration.

And what you persist in thinking of as a weak link became obsolete a long time ago but only a few people realize it. Keep looking at the photos.

So, that being dispensed with, you still haven't answered my question... What advantages does a curved pin have over a straight?

By the way - I don't like the big eye either. But I'm not a machinist and this is the best off the shelf hardware I've been able to find. If I had my druthers I'd go for a smaller eye and a longer shaft. But all of the illustrated design variations are very idiot resistant - effectively idiot proof - and it's really not a problem.

And, again...

>
I don't think that anyone capable of doing this (flipping the pin) should be flying.
<

I really hate to do this next part 'cause I've got a lot of respect for the rare person who comes up with an original concept and just the opposite for one who says that folk who try to improve things are evil. But...

The wire thing is interesting but I'm having a hard time screening out mental images of broken strands, shredded Dacron, and bloody fingers. If you want to pursue it I'll keep an open mind and follow your progress with interest, respect, and admiration but I think - and, hopefully, by now, you may agree - that this is another instance of Paragraph 6 creep.

There's some pretty ugly things that can start happening when you load things up to the couple of hundred pounds and more that this concept has gotta endure.

But, yeah, you're on the track of helping now.

Jim,

No, it's looking like your vivid memory of any exchange we might have had on the subjects of rivets is a lot more plaqued up than my faint recovered one. I've never argued about an obvious release issue, it is impossible for me to have eventually fixed the same problem with my barrel release 'cause - as we've just seen - a straight pin based assembly is inherently immune to the malfunction, and there would have been no place to add a stop. The whole goddam thing is a stop.

Also, the last time I went up behind a tug with any element of a release/bridle configuration that wasn't of my own making was 1993/05/30 at Pike County Airport in Ohio. I wasn't using a curved pin barrel then and you weren't there.

And I've never been stupid enough to use anything other than a straight pin in anything I've put together. They were on my glider and, I believe, one of the tandems better than a year before you first thought of a Dragonfly as anything other than an aquatic insect.

But anyway, to answer your question...

When you want to invent the wheel you use a compass. When you want to invent a hang glider release you use a ruler. Bobby used a compass to design his release. To carry the analogy over he came up with a square - no, that's a bit too harsh - pentagonal wheel. It gets you there but the ride really sucks.

Wichard also used a compass but they did things right to meet their objective. They wanted something that would handle a fourteen millimeter diameter spinnaker sheet under an eleven hundred kilogram load. That's not what we want to use for towing gliders.

Tim Hinkel and I used rulers. Our analogous wheels are round and our rides are really really smooth.

With respect to the barrel release issue at hand, here's part of the answer to your question...

>
Tadd's are less prone to accidental release (read: nearly impossible).
<

That's yours from 2005/08/31 19:46:59. But that's a minor issue.

Let's go to basics.

Schweizer sailplane releases, spinnaker shackles, Keller/Koch two stage releases, the quick release panic snap (for horses) core of the original Bailey-Moyes two point AT releases, Tim Hinkel's two point AT release, and curved and straight pin barrel releases are all SECOND CLASS LEVERS.

A second class lever has a fulcrum at one - in our applications the upwind - end. In the case of a barrel release it's the parachute pin eye.

The load force is applied between the fulcrum and the far end of the lever arm, i.e., pin shaft. In glider releases the load force is sometimes all but usually some portion (roughly half or a quarter, depending upon the configuration) of the tow line tension.

An effort - in the area of discussion, retaining - force opposes the rotation of the lever and is applied to the lever arm beyond / downwind of the load/tow force. This force is maintained, in the relevant example, by the the barrel.

So to maximize the efficiency of our second class lever we want to apply the load force as close as possible to the fulcrum and keep the lever from rotating by applying the effort force AT THE EXTREME END OF THE LEVER ARM.

In other words, we want the weak link (if you must) mashed into the edge of the eye and we want the inside barrel wall to contact the pin shaft all the way at the far end.

In yet other words, our goal is to minimize the retaining to tow forces ratio.

(We're at the playground. Vandals have cut almost half the seesaw off just beyond the bar, leaving a ten foot plank on one side. It's easiest for the skinny kid - Stan - to lift the fat kid - Ollie - if the latter sits as close to the bar as possible while the former goes to the far end of the plank.)

Also, we don't want the pin partially rotated towards the open position while under load 'cause that allows the weak link to move away from the fulcrum, side load and thus stress the shaft, and increase the hell out of the pressure on the barrel.

(We don't want Ollie to start scooting out towards Stan 'cause the board's gonna start bending (and it's a little marginal anyway) and Stan's gonna start getting real unhappy.)

In a straight pin barrel release the weak link is forced as close as possible to the fulcrum/eye/centerline and the extreme downwind end of the the shaft is contacting the barrel wall.

(Ollie is sitting practically on top of the bar, the plank isn't bending anywhere, and Stan can maintain the situation with the little finger of his left hand.)

At 2500 feet or violent lockout, whichever comes first, the barrel is slid clear with very little resistance and the pin remains fixed and in alignment with the tension force until the tip of the lightly loaded pin is cleared. Tow's over.

(Oops, forgot to tell ya, the vandals also dug a ten foot deep trench under what's left, leaving the remaining half plus of the plank free to rotate all the way down. Stan puts his left hand in his pocket, Ollie disappears into the trench, and the plank is never stressed.)

In a Bailey release the webbing forces the weak link off center and the curve of the pin at the upwind end angles away from the centerline at a thirty degree angle, thus accommodating the weak link's forced expatriation.

(Ollie can't sit near the bar 'cause the vandals also pounded a bunch of nails up through the bottom of the plank over the first two feet. Stan can hold the plank - which is starting to crack a bit - with one hand but he's not real happy about it.)

The curved pin contacts the barrel at a point half way down the shaft. The upwind half of the shaft is under a tremendous degree of side loading and there is tremendous pressure at the contact point. The back half of the shaft isn't serving any function. You could saw it off for all the good it's doing and, in fact, should do so because of the problems it's about to cause.

(Stan has inexplicably moved to the midpoint of the plank and is straining himself dangerously to maintain his grip with both hands. Why is he doing this? I dunno - bad acid, hallucinating scorpions all over the back half of the plank?)

The glider is locking out and the tow tension is building up fast but it's really hard to slide the barrel back because of the pressure of the pin.

(Ollie spots Ramone - his crack dealer - to whom he is currently 5K in the hole, walking towards him with an Uzi dangling from his right hand. Suddenly the trench is looking like the best option under the circumstances. He wants to be dropped really fast but Stan can't just let go 'cause he'll really tear up his hands. He starts working his way back into scorpion territory but it's tough going.)

The barrel finally gets clear of the high/contact point of the curve and is thus able to start taking advantage of the wasted length of the lever arm. But as the barrel continues back the pin rotates more in the open direction, thus allowing the weak link to move farther away, neutralize some of the gain of the mechanical advantage, and side load the pin with a force near the limits of its strength.

(Ramone is raising the Uzi and Ollie is scooting back towards Stan - who has by now realized the scorpions were imaginary - but his job isn't getting much easier.)

As the barrel reaches the end of the shaft the pin has rotated to the point at which the weak link contact area is fifty degrees from centerline and the side loading permanently deforms the pin as the release is effected.

(Stan has made it to and off the end of the plank and Ollie drops into the trench just as the cops happen to arrive but the board won't ever be good for much of anything again.

In the field and with the flimsy weak links everyone uses the pin doesn't get destroyed but I do know that actuation under a 220 pound direct load will destroy a Bailey pin. Mine goes to 400 pounds no problem at which point actuation force is still pretty reasonable.

(This is so much easier to demonstrate at the airport.)
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jimrooney

2008/02/13 09:06:35

Selective memory I see.

When you first showed me the straight pin release, I told you I wouldn't touch it because "I had to give instructions on how to use it so that people would not rig it wrong". I showed you how you could rotate the pin sideways and close the barrel... and pointed out how this was not possible on a Bailey release. I told you if you fixed that, then I'd use it.

You modified the release to include a stop.
You made this modified release specifically for me.

Don't tell me your releases had this before then. Oh you had barrel realeases, but they did not have stops... they could be rigged wrong. The Highland boys didn't see a problem since students do not rig them... only we do. I don't agree with this conclusion, but it's not my company.

Oh..... in failing to answer my "what advantage does a straight pin have" question... you attempt to reverse it to "what advantage does a curved pin have".

Well, two things....
One... no one's trying to improve on your design. The bar was set with the Bailey... it is to YOU to "improve", which you have not done.

Two... The advantage of a curved pin... it can handle differing thicknesses of materials. Yours can't. You have a very narrow range and then you run into the problem of that pesky stop. That's why yours have weaklinks on both ends... nice and thin.

Call it insignificant if you will, but YOU are the one that is the incumbent... the onus is on you, not Bobby.

Jim
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brianvh

2008/02/13 14:19:02

Tad - that Stan and Ollie routine was a masterful bit of expository writing. So much so that it got me to go digging through my harness bag to pull out my bailey release and check out your statements. The curve is there to prevent the weak link from hanging up on the eye, but you're right: it means the pin hits the barrel pretty darned close to the fulcrum.

I suggest a compromise: an initial curve followed by a straight segment. I've just tripled the machining cost, but it might be worth it.

Brian Vant-Hull
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hefalump

2008/02/13 17:04:36

I guess I need to explain this again because you just don't see the failure mode.

Refer to your picture titled "Barrel Release Connection – Correct". I'm aware that photo is "bird's eye" but follow my directions as if it was from the side. Note: in the picture the pin is ROTATED back on TOP of the release and the release is closed, vinyl tube used instead of aluminium for clarity.

1) Allow the bridle with the weal link to move down and in the direction of the barrel release so that the end of the bridle is directly under the eye.
2) Move the barrel release away and the bridle weak link assembly towards you
3) Allow the far side of the weak link loop to pass under the release between the Eye and the end of the barrel.
4) Pull tension on the bridle and weak link assembly and allow both sides of the weak link to stay on the near side of the eye.
5) Continue to pull tension that would be encountered under tow.
6) Slide the barrel back for release and see what happens … it locks in "Death Mode".

Yes this is a very deliberate action however it can easily be reproduced by accident with the bridle slack.

Your keel release is not susceptible to this mode of failure because of the lines attached to the release and some point forward the glider. But I do not tow with a keel release so the barrel release on my right shoulder is primary and the barrel release with weak link on my left shoulder is backup.

The Bailey release with the "over slide" barrel that contacts both the top and bottom of the eye is also not susceptible to this failure mode.

To avoid one single overly long post I'm going to break each comment into it's own post. I could also do this exchange by P.M. and save everyone the drama … but I want to do it in full view of the group to keep everything Honest and Civil.

JD
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hefalump

2008/02/13 17:13:48

I have already discounted the my "folded pin" release constructed with wire because of wire splinters. I'm sure I could manufacture some super slick stainless folding pin but that violates the "off the shelve" parts and the why re-invent the wheel concepts.

JD
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hefalump

2008/02/13 23:07:04

I re-read the accounts of Robin's accident and I am hesitant to talk about it … the video was very disturbing. However, with most aviation accidents it's a chain of otherwise harmless or manageable events that combine to fatal result.

The first event was the foot launch aerotow which resulted with a dragged wing tip starting the fatal chain of events.

Second, the bridle did not release. From what I read, he had multiple wraps of weak link in the spinnaker release. The release gate is thinner at the hinge and thickens towards the end of the gate. The release opened properly but the multiple wraps of weak link did not clear the thicker part of the open gate. As tension on the bridle increased it may have acted like a "Chinese Finger Trap".

Third, the weak link did not break. From what I have read, he was not using a proper weak link. I have read reports of it being referred to as a "strong" link.

I'll end the chain of events there.

I do not know if he had a secondary release and the tug pilot may have only become aware of the lock out after it was too late.

Break any of these events and the accident doesn't happen.

A clean launch either foot launch or on cart ... no accident. However, the pilot may have had to deal with a release failure at altitude.

A single loop of weak link in the spinnaker release which is common practice, the pilot would have been able to release the tow line and make a safe landing.

A proper weak link that would have broken as the lock out deepened and the pilot may have managed a non fatal landing.

The release failure was caused by a specific and now know problem.

Quite frankly I had not anticipated this type of failure, and based upon your attempts to create a system with out the Spinnaker release only after the accident you had not anticipated it as well.

Although the spinnaker release was designed for larger diameter ropes and much higher forces, for an off the shelf release, although not perfect, it is well suited for our application provided a single loop of rope or weak link is used. It opens with a 1⁄4 throw with very little effort while loaded from zero to the rated capacity.

Barrel releases and multi string releases are very reliable, but even they can be defeated. For example, with a barrel release, by folding the pin over instead of rotating or with multi string releases by looping the strings in the wrong order.

JD
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hefalump

2008/02/13 23:45:48

>
What...way.
<

It's statistical analysis. Before you can predict probability, in this case probability of release failure (1 in 100, 1 in 1000 and so on), you need a group of sufficient population (tests). 3 tows per year and all your bench tests is not enough of a group to claim 100% effectiveness.

It's like flipping a coin twice and it happens to land heads up both times, then proclaiming that a flipped coin lands heads up 100% of the time.

Every engineered system has a failure rate. Every event has a probability.

"Given a long enough time line everyone's life expectancy drops to zero", Tyler Durden.

JD
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Flying Lobster

2008/02/13 23:56:00

beware of winky weak links!!
*
Flying Lobster

2008/02/13 23:58:42

JD--

the way I read it I think what he meant was only a total idiot would claim 100% effectiveness based on one user flying 3 times a year. Makes sense to me.

marc

beware of winky weak links!!
*
jimrooney

2008/02/14 01:37:28

(3 tows/year) The crux of everything Tad says here.
He is the ultimate sideline quarterback.

Yet he is constantly insulting and condescending to anyone that doesn't agree with his assumptions and conclusions.... which are based on a horrible lack of experience.

It baffles me that people even listen to him.
Jim
*
0155
*

[Tad Eareckson]

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

"temp" set

Look at the pictures, read the captions, run the slide show.

Then somebody please explain again to me why the "standard" barrel release was such brilliant freaking idea.

[hefalump]

Looks like Tad has been busy in his work shop doing some test to discredit the Bailey release. We might have done a public service keeping him occupied in his work shop and out of public.

Come on Tad lets get reasonable, for the tow forces involved, the curved pin is fine. You had to put 220 lbs of force to get the curved pin to bend/fail. For a “Pro-Tow” configuration (shoulder tow) that would mean 220 lbs of force on each shoulder, so that's 440 lbs on the tow line. For a solo tow … I doubt it.

Now let’s talk about a two point tow, the keel point and shoulder bridle point share the load in half. Each shoulder shares half of that load. To use the same numbers, which I think are high, 440 lbs on the tow line would be 110 lbs at the barrel release at the shoulder.

Sure with 440 lbs tow line force there would be 220 lbs on the keel release, but no one except for you is using a barrel release at the keel.

I don’t even think the aluminum tow line carabineer can take 440 lbs.

The problem with you is that if you find a way to miss-assemble anyone else’s release “it’s a design flaw” and “inferior”. I point out a very valid problem with your barrel release and your response is “Well no body should do that” or “they would have to be an idiot”.

Bottom line, once the Bailey release is properly assembled and closed it will not foul either slack or under normal expected aerotow loads. Your release on the other hand, all closed up and ready for action, can be fouled simply by letting it get slack and then applying slightly offset tension.

I’ll take the Bailey release, at least I can control it’s “flaws”

I wish I had my video camera and one of your releases. I would make a quick little movie of just how easy it is to foul your release.

JD

[Tad Eareckson]

Jim,

In your post of 2008/02/11 you were discussing - somewhat incoherently as usual - a rivet STOP which prevented the misassembly which JD effected which can and did lock a curved pin barrel release. You didn't argue this issue with me and I never fixed the problem because it never existed on any of my designs - which predate your appearance in the sport. It would have been as if you were trying to tell me how to adjust the carburetor on my hula hoop.

In your 2008/02/13 post you bizarrely morphed the discussion to an entirely different STOP modification with which I came up in response to a request from Adam.

Lemme give you some background...

On the evening of 2002/06/08 Ric Niehaus wanted my spare one point assembly. At the picnic table and in my absence Jeff Harper cautioned him that straight pin releases could be locked up and so demonstrated.

By the time Ric got back to me Jeff had split and Ric was unable to reproduce the failure.

Four days later I had figured out what he had done and my reaction was then and remains to this day, "WHAT THE HELL KIND OF TOTAL ASSHOLE WOULD DO SUCH A THING?"

The flip lock - as illustrated in my photos - has absolutely nothing to do with the shape of the pin shaft. It isn't possible in the Bailey 'cause that release incorporates webbing of a width - half inch - which matches the eye diameter. I use leechline. The other one is poorly engineered - being at the same time overbuilt and understrength as well as inefficient - but it is idiot proof.

I reacted by making all of my designs highly idiot resistant.

Late in the 2006 season I figured out that one could make a better barrel release than the crap on sale at the counter by just looping a length of leechline through a straight pin eye and an aluminum tube and tying the ends at the aft end.

Sunny and Adam perked up quite a bit but said they needed it idiot proof. (Adam told me they had had an incident in which someone had hooked into a spinnaker shackle.) I went home and came up with the stop modification. When I returned with a unit they perked up a bit more and you took note and requested a pair with shorter barrels - which you received (for free) upon my next excursion.

So - No, I did not develop this modification specifically for you.

Now, lemme tell you how I feel about the stops...

I have a stop version barrel on my port AT loop and a four-string on my starboard. I use the stop modification NOT to keep myself from flipping the pin and locking myself up but because it makes a nice bumper to arrest the travel of the barrel upon normal actuation.

There has never been anything wrong with any of my barrel releases and I'm never again going to put five seconds of effort into any modification to prevent some moron from getting creative and killing himself. The release without the stop is just about perfect. People with enough intelligence to see the obvious superiority will use them and be safer for it. Anyone capable of inadvertently locking it is just more crud in the gene pool and I want as many as possible of those people dead before they can get anywhere near a voting both again. This is natural selection at its best.

Yeah, I actually did answer both your questions. So I'm wondering... How come Brian got it but you still don't have a clue? (I've really gotta cut back on the rhetorical stuff...) But lemme try again...

A long time before chimps and humans went their separate ways some hairy knuckle dragger was trying to roll a big log to check for juicy beetle larvae underneath. The job wasn't going well until he noticed a heavy long STRAIGHT stick lying nearby. (There was a curved one a lot closer but by that point in history hominid cranial capacity had exceeded the volume of a walnut.) He shoved one end of the stick under the log, put his hands on the other END (not MIDDLE), and within another four seconds was gobbling up crawlies to his heart's content.

Thus was invented the SECOND CLASS LEVER. Once you get a grasp of that concept you'll find yourself much better positioned on the evolutionary scale.

With respect to your assertion that my straight pin barrels can't handle differing material thicknesses...

I closed my personal copy over a loop of 3/8 inch Yale Crystalyne (11500 pounds) and it worked fine. Exactly what are you trying to tow with yours?

And, no, I don't have weak links on both ends - I don't use weak links as you define them. But, in any case, what's your point? Why wouldn't anyone who had done the walnut thing want the redundancy and why would anyone want to increase the material diameter and thus the side loading on either a curved or straight pin release?

JD,

You don't use pilots to design, build, and certify the supersonic fighters. You use certified smart people. They're called engineers. They think flying is cool but not all that intellectually challenging. They have to understand physics and mathematics on top of being literate.

When Airbus wants to put the A380 into the air they don't do it by building hundreds of them and handing them out to pilots to see if they can find any problems with any of the forty gazillion parts that go into them. They build ONE, they know what it's going to do 'cause they know what the hell they're doing, and they bench test the crap out of it. Then they hand the keys to a pilot who knows what he's talking about who takes it for a totally uneventful spin around the block.

That's also how they do hang gliders but pilots never seem to be able to grasp this concept. Certifying a hang glider to HGMA standards requires ONE glider, ONE pilot, and as little as ONE flight.

USHGA Tow Committee Release Test Procedures require ZERO flights.

So exactly what qualifies you to tell them/me/us how to certify stuff that goes into the air. Bench tests are not coin tosses. Good designers use science to make predictions. You seem to be way more concerned about my stuff failing in a manner that you can't even imagine than you are about crap that fails in the air all the time in entirely predictable and well known manners.

Try naming me one instance in the history of glider towing in which there was a release problem in the air that wasn't predictable on the ground.

(When the Challenger disappeared into a big orange fireball over the Atlantic there were a whole bunch of non pilots who were only surprised that the explosion occurred seventy-three seconds into the flight rather than on the pad.)

Tell me how releases and bridles function differently aloft than they do on the ground. In other words - just how much effect does a thirty mile per hour breeze have on the mechanics of operation?

When you realize you can't come up with any answers I'd really appreciate it if you would forever drop the crap about flight testing.

My engineered system does, as you say, have a failure rate. It's precisely the same as my basetube failure rate - ZERO. It has to be.

You notice that Jim is using technology that I first developed - spinnaker shackle, redundant weak links, straight pin barrel releases? You also notice that nobody is going aloft with anything he's come up with?

That's cause I spend no time flying and a lot of time thinking and he spends an enormous amount of time flying...

Jim referred to me as "the ultimate sideline quarterback". So, in a discussion which has nothing to do with flying and everything about design - who's the ultimate sideline quarterback?

As I said before, I participated in the Dragonfly promo tour at Currituck in August of 1991. I had long before realized that a lot of ground based towing releases were junk and I could do and was doing better.

I purchased one of their releases:

Original Bailey-Moyes Aerotow Release - Closed
Original Bailey-Moyes Aerotow Release - Open

then went around to tack shops looking for nice light panic releases I could incorporate as the core of my own assembly. I wasn't having much luck but was also sniffing around sailboat equipment shops and eventually stumbled upon the right display case.

There was a Wichard 2673 Small Bail Quick Release Shackle right in front of my face and I said, "HOLY SHIT!! This is an aerotow release! I don't know how I'm going to configure it but I'm going to leave with it and find out."

I was, however, bothered by the gate which increased in girth from hinge to end and the notch at the end. I experimented and neither of those features seemed to be much of a problem but was never happy about them. It was, however, the best off the shelf solution I could find but I never stopped looking for something better.

I configured the spinnaker shackle in keeping with the manner in which its designers intended. I secured it at my apex and ran a leechline lanyard through some rings on my port downtube. You could see it, it flapped in the breeze, you'da loved it. It first went up (behind a Cosmos trike) on 1994/09/04.

Around that time it seems somebody in Florida recognized the potential of the same piece of hardware but decided it needed welding, drilling, cable, and a bicycle brake lever. I wasn't impressed but had to admit that it slapped on pretty fast.

Some of the shackles had a bit of sharp edge in the vicinity of the hinge and were chewing up weak links. So rather than just spending a minute or two with a small fine file and taking care of the problem (sorry, could well be someone I like and respect - but) some IDIOT decided that the way to address the problem was to drill another hole and mount the thing perpendicular to the alignment for which it was designed.

>
hefalump

2008/02/07 12:51:57

This is an example of how people trying to "improve" on a design can undo redundancy and safety.
<

That is an amazing illustration of a self contradictory statement. Mechanical advantage IS, JD, part of the safety equation. It's quite analogous the lift to drag ratio of the glider itself. Kinda like turning a fifteen to one kite into a three to one for no reason whatsoever.

But anyway, the point of some of the above is that...

NO, Robin was NOT killed because some previously unknown AT release defect. Whoever it was that ground the protuberance off the panic snap in 1991 knew what he was looking at. I knew the spinnaker shackle was problematic within a second of laying my eyes on it. John Claytor did a nice job of incorporating what I believe was a Ronstan snap shackle which nobody could induce to hang up. Tim Hinkel has built a flawless slap on assembly from the ground up. My remote barrel system is the best in the world but it's gotta be built in - and people who care about that kind of performance are all flying one point anyway.

The spinnaker shackles failed - make that present tense - ALL the time. On 200/08/26 for example, Sunny had a Dragonfly stalled out from under him (at altitude) 'cause one of those things didn't function. There were endless discussions about them.

But we always had enough margin and/or redundancy going for us until 2005/01/09 when everything lined up wrong.

I'll get back to some of your other issues about that accident later but for the time being I'll skip to address your last post and related comments.

With respect to your first paragraph...

The Bailey style release has already been discredited amongst people who know what they're looking at. (Note, for example, Brian's reaction.) So I wasn't busy trying to accomplish that - it's a given. What I was doing was putting a tremendous amount of work into making it easier for people who slept through fifth grade science to have an "OH!" moment.

Based upon your comments it appears I have again fallen short but I really don't appreciate them in any case.

Moving back to yours of 2008/02/13 17:04:36...

No, we were on the same page with respect to the procedure for lassoing the eye. I had never found that a possibility.

But I took you at your word and experimented again. Took me a while but I eventually figured out how you got into death mode.

You didn't find a valid problem with my release - you found one with the experimental configuration you put together.

You were using something under an eighth (08/64) inch diameter for the base material running through the eye.

The malfunction you simulated is not possible on my barrel releases 'cause the 08/64 inch leechline kicks the weak link back out of death mode. You drop down to 06/64 it gets feasible. 05 - no problem.

You don't seem to have yet figured out that the shape of the pin - straight or curved - has NOTHING to do with the ability to lock up the release and EVERYTHING to do with the thickness of the material engaging it. (See above.)

Yeah the flared barrel of the Bailey does seat nicely on the eye but does nothing to enhance the reliability. It's the half inch webbing that overkills that malfunction out of the realm off possibility.

You haven't addressed the photograph:

Barrel Release - Wide - Straight Pin

YOU should absolutely love this too. It's completely idiot proof AND its performance still sucks - albeit not nearly as much as the one of which you are so fond.

You haven't even addressed the Cut Pin job. It's also idiot proof and has crappy performance but can withstand a significantly higher load than the full curve.

If you're going to comment on my systems you should take the trouble to find out what they are. It's pretty much a no brainer that you didn't download the "mousetraps" file to which I referred you thirteen days ago. If you're not using my specs you're not experimenting with my system. If you don't feel like registering for skysailingtowing I'll send you a copy of what's currently up there upon request.

Please note that since you so far have not bothered to RTFM I've had to rewrite a lot of the material that's already in there for your personal convenience.

Anyway... Wanna make this interesting? A thousand bucks says you can't get my personal barrel release - the very same as illustrated in the following photos:

Secondary Bridle Assembly
Barrel Release - Stop
Barrel Release - Stop - Fore - Top
Barrel Release - Stop - Fore - Port
Break Link - Installation

to fail in the manner you described after I've engaged the weak link, rotated the pin, and slid the barrel fore.

Rules...

weak link:

Greenspot, 130 pound, tied in a loop such that, when mounted and engaged, the protrusion exceeds the diameter of the pin eye.
Installed via a Lark's Head on the drawstring of a small nylon stuff bag.
Gonna look like:

Break Link - Installation

manipulation:

The barrel stays where I put it.
You spend five minutes of desperate futility trying to effect the lock.

At the end of that period I'm gonna put three twelve ounce sealed beer cans in the stuff bag and place it on the ground - gross weight: 1147.5 grams - about two and a half pounds. Then I'm gonna raise the snap shackle such that the release assembly is aligned vertically over the bag but not under tension.

With my other hand I will grasp the barrel and by it slowly and smoothly attempt to lift the bag off the ground. If any daylight appears between the bag and the grass you're gonna be very happy.

I only need the beer to overcome the built in friction between the barrel and base. And, of course, to celebrate upon completion of the exercise.

Fair enough?

As much as I'd enjoy taking you to the cleaners it's only sporting to advise you to consider the fact that although I never fly - I lied about the three times a year, I use a stunt double - very similar barrels of mine are going up quite a bit, some of them with the people who know what they're looking at.

My double, Ric Niehaus, John Dullahan, Hugh, presumably Jim Rooney and Dennis Pagen, possibly Kevin Carter, and, most significantly, both Ridgely tandems. And I haven't heard about a whole lot of problems. (Can you IMAGINE the field day Jim would have?) John Simon was using a knock-off, last I knew.

I suggest you respond to this in the same manner Matthew and Jim responded to my proposed actuation speed challenge.

But anyway...

What you think of as a weak link became obsolete about a season and a half ago. They now look like this:

Bridle Link - Fore
Bridle Link - Construction

And if you get a sinking hopeless feeling trying to score with the Greenspot crap, you're gonna be in tears just thinking about defeating an properly designed configuration.

No, the curved pin is not fine for the tow force range limited even by the ridiculously understrength single loop of Greenspot that a lot of the smarter pilots are doubling up (any glider from two to five hundred pounds can do so and remain within USHGA specs).

Check out this golden oldie...

Greg DeWolf

2000/09/01 09:48:29

>
...(however, I have heard of some complaints of the Bailey's being difficult to work under high loads).
<

I didn't say it took 220 pounds to mangle the pin. I said "something UNDER a direct loading of 220 pounds". I (still) don't know what the threshold is. Prior to yesterday I just knew that when I suspended myself under a release some years ago and actuated it, it assumed the shape you see in the photo.

And the deformed pin isn't the problem - it's just a symptom. The problem is that the side loading required to make the crease results in so much pressure inside the barrel that the release becomes practically nonfunctional at relatively low towline tension.

Yesterday I configured my rig to run the tests on your favorite piece of junk - the unit you see in:

Barrel Release - Curved Pin - Locked
Barrel Release - Curved Pin - Modified

I ran forty tests with incrementally increasing loads from 62 to 175 pounds. I was unable to measure required actuation force (what's needed to pull the barrel) in that configuration but subjectively...

Things started out poor and became dangerous long before 140 - single loop weak length strength - and totally insane LONG before 175 - and that's still only 87.5 percent of double loop (200). So there's probably a good reason Sunny and Adam haven't replaced the straight pins on the tandems with curved.

The pin did survive the test series undamaged. The barrel didn't. I terminated the nonsense after I noticed sparkling particles on the table and realized I had been tearing aluminum off of the inside of the flared end. (Remember me predicting that modification to be a lousy idea in my latest photo series?)

By the way, the USHGA Tow Committee Release Test Procedures require flawless function of a release under a direct load of 600 pounds. I personally think that's bullshit - I'm perfectly happy with something that does one and a half times weak link - but this piece of crap is a total fucking joke no matter what standards you use. I doubt it has any more than five or ten percent of the performance of mine.

So, again, please explain to me... What's the curve doing FOR us?

Let's look at your numbers...

You don't divide by four to consider the performance your shoulder mounted barrel releases for two point towing. You divide by two. The reason - You don't EVER actuate a barrel release in two point towing. Check out the discussion in the recent "Weak Links and Tow Bridles" thread.

Actually, the aluminum tow carabiner is supposed to be able to take well over ten times what you estimate. A report from Jim, though, indicates they may not hold up to that kind of abuse very well.

By the way, you never told us why you rotated the pin the wrong way - but I think I figured that out a couple of Saturdays ago. I was idly toying with a Bailey and discovered that it's a pain in the ass to insert the tip of that pin between the two runs of webbing. It's REAL easy to rotate it the other way.

More later.

[hefalump]

Know what Tad … I just don’t care any more. You use what you want and I’ll use what I want, that’s the beauty of this sport, we are all responsible for our own choice in equipment.

You have not convinced me that your release is any better than the Bailey, it’s a barrel release. You did not design any thing new, and use the word design in the loosest possible meaning. You took a good idea, made a few insignificant changes and then claim you came up with something so much better. In fact you may have made it worse. Even your four string release is nothing new. Those types of “loop force reduction system” have been used for centuries. It’s just that two loops maybe three is all that is needed, you add a fourth and claim your a genius and seek recognition and validation.

You just don’t get it, I INITIALLY tried to politely point out problems with your stuff so that you could make changes based on honest feed back, but you snap back claiming that there is no problem. As it turns out a lot of people have tried making suggestions to you in the past and suffered the same results ... you may need to your on your interpersonal skills.

Remember this all started because I admitted to miss rigging a release and at a fly-in a couple of years ago I pointed out something to someone that might have been dangerous.

I find your devices contraptious and Rube Goldbergesque. You say that it only takes a 5th grade physics level to come up with a better design, but that is exactly what your stuff looks like, 5th grader level, especially that keel release monstrosity.

It’s a battle of wits … and you’re out of ammunition.

JD

[Tad Eareckson]

Oops - one more zero: 2000/08/26

JD,

You started out on this release thread clueless, peaked at:

>
...sham on me for not paying more attention to your release.
<

(despite the spelling problem) and now you're right back down to where you started.

Thought there might have been something going on when you actually started testing, experimenting, and participating in a dialogue but I've been wrong before.

So I take it you have no interest in putting your money where your mouth is? Didn't think you would - good move.

(Gee, I was kinda hoping for the chance for some extra income. Any other takers?)

The multi-string, by the way, is Steve's (re)invention, not mine. Where are you finding this information to the contrary? But yeah, he does have a lot going in the genius department.

Thanks much for your opinions but a value them as much as I do the growls of an Irish Setter. Not a lot of substance to them. I'm just wondering how I managed to get so stupid in the time which has elapsed since your post of 2008/02/06.

Brian,

Apologies for taking so long to get back to you. Thank you so much for your comments of 2008/02/13 - a much needed change and break from all the hate mail.

Don't know if you've waded through the volumes above but - no - the machining cost for the pin is still two and a half bucks.

The curve has zero bearing on the reliability of the release - any curve whatsoever is pure detriment.

My theory as to why the curve is there is 'cause those were the kind of pins available in the shop when Bobby was getting creative and they give off a false aura of suitability. He incorporated them, Dennis drew them and published the pictures in his book, everybody imprinted on them, and nobody ('cept me and one or two others independently) ever questioned them.

So happy I got at least one more person thinking about this stuff. Small victories.

[hefalump]

Tad,
Don't assume that my abandonment of this topic is in any way me acquiescing to your assertions. It’s simply because your last post was so riddled with false claims, poor engineering techniques, and lousy methodology that I neither have the time or energy to dispel each of them.

The challenge as you offer it would not test the defects I have detected in your release. I believe this is why you are so specific in your challenge parameters. You know your release can fail under foreseeable real life circumstances so you frame your challenges to avoid these conditions. That is understandable; anyone making a bet will try to stack the odds in their favor.

I’m in awe of arrogance to claim that your release systems are 100% effective and that your remote barrel release is “The Best in The World” without any endorsements except your own. You are truly a megalomaniac.

JD

[Batman]

Actually JD, I have to stand up for Tad under these circumstances. He's not a megalomaniac as you so elegantly put it ....

He's just an asshole ....

Sorry, but I felt someone needed to stand up for him

[jimrooney]

meg·a·lo·ma·ni·a (měg'ə-lō-mā'nē-ə, -mān'yə) Pronunciation Key
n.
1. A psychopathological condition characterized by delusional fantasies of wealth, power, or omnipotence.
2. An obsession with grandiose or extravagant things or actions.

Oh, I don't know... sounds pretty spot on to me.
Tad thinks a bit too highly of himself and generally detests everyone else.

But yeah, no argument on the asshole part.
I'm a pretty easy going guy and he irritates me to no end.
(which is why I now block his posts)
Jim

[Tad Eareckson]

OK, you have neither the time nor energy to dispel all of my false claims, poor engineering techniques, and lousy methodology. I absolve you of the responsibility.

SO HOW 'BOUT JUST ONE?

Or was that just a reworking of one of the statements that Jim, Marc, and Chris have used when they find they've painted themselves into corners? Just hurl some generalized insults and dramatically storm out of the room.

You're confident that you've found a defect in my version of the barrel release. I've given you an opportunity to make an easy thousand bucks by proving the validity of your claim.

If, under the terms I've offered, you dawdle and eat up the whole five minutes you'll be raking in the dough at a rate of twelve grand per hour. If it's as easy to lock it up as you describe five seconds will be plenty and you'll up the rate to $720K an hour for very minimal effort.

Yeah, there've gotta be some boundaries to this arrangement.

For example, if I say "OK" after David Copperfield says "Betcha I can turn your freakin' glider into a tiger right in front of your eyes." I'm gonna need an ATM card, whip, and chair real quick and not necessarily in that order.

I can connect a leechline bridle to my barrel release and, with the former in one hand and the latter in the other, tie a Lark's Head or Clove Hitch around the barrel and lock that sucker up but good. I can, however, do that just as easily and a whole lot more securely using YOUR barrel release.

But, in Towing Aloft, Appendix III, Section II there are some qualification tests which my release - and yours - will easily pass.

No, I'm saying there are no real life circumstances that can keep me on tow for longer than two seconds (barring something along the lines of a bullet entering one side of my helmet and exiting the other). Tow line tension zero to six hundred pounds.

You don't like my restrictions? Let's haggle. Let's hear the terms YOU'D like.

But just to save us some time... We're talking about MY properly configured system - I make the connections. If you wanna see what it looks like...

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

Primary Release System - Composite Overview

'cept with the "monstrosity":

Keel Release - Connections

swapped in where the spinnaker shackle used to be and:

Secondary Bridle Assembly

'cept with a:

Triple Ribbon Bridle

swapped in.

You can see details of the components in the photo set. Take particular note of:

Bridle Link - Construction

So whatchya got?

[brianvh]

I remember thinking your barrels looked mighty skinny, Tad. How well do they pass the winter gloved finger test? That's the test I'd like to see...done while hitting the testee with whiffle ball bats to see how well it performs under stress.

[Tad Eareckson]

Brian,

Short Answer -

It simply isn't an issue. In fact - I find my long uniform barrels very much preferable to the short fat flared Bailey jobs.

And if I see an angry mob heading my way with wiffle ball bats - I ain't gonna be fuckin' around anyway. I'm just gonna relax my bite on the four-string trigger.

Stress - along with interpersonal skills - is something I just don't do. That's how come my release system is configured so's I don't have to reach for anything or make any effort and built so's I know it's gonna work.

But still - you're WAY better off with my straight pin barrel. I'll flesh the mechanical advantage thing out in the

Long Answer -

Give it a skim. Nobody else is gonna bother but I think you'll find the numbers towards the end interesting. I'm also addressing a couple of issues JD raised.

(Tim - Skip down to the end.)

If you wanna get a comparative feel for these two barrels...

Fill a five gallon bucket a bit over half full of water. Tweak it with the bathroom scales if you want to get an accurate 25 pounds. That's the maximum the USHGA Tow Committee allows for actuation force for any kind of release.

Stick a four inch strip of masking tape longitudinally on the aft region of one of your outboard cambered Falcon battens. A thin strip will do - you can leave a lot of aluminum exposed.

Using a short length of light leechline tighten a noose around the aft batten tip and tie the other end to the bucket handle.

Put one of your winter (if you must - neither Ridgely nor I do winter) gloves on, grip the length partially covered by the tape, align the batten vertically over the bucket, and lift.

Now lose the batten and Lark's Head your Bailey onto the bucket handle as you would to one of your harness's AT loops. Also doable but much less comfortably so.

The Falcon batten is, I believe, 10 millimeter - a little thicker than the 3/8 inch tubing I use for my barrels but I glue nice rubbery heat shrink grips onto them so that brings them up to .40 inches - about the same as the batten diameter - and makes operation REAL easy.

You (and I) tow two point but you're not gonna use the barrel unless you've had a bridle wrap and have gone into one point mode. Let's put a double loop of Greenspot - 200 pounds - on your secondary bridle - which is about the strength that most people should be using.

That means that you need to be prepared to pull a bit over 32 pounds (see below) on your Bailey barrel - way out of specs. Even with a single loop you're talkin' over 22 - and that's getting marginal.

With my straight pin that double loop limits you to under 10 pounds.

Try the bucket exercise again using those figures with the corresponding barrels and see how things feel.

By now you've figured out that the answer to question you raised is rather the opposite of what you expected but I've still gotta amend (as I've said before)... I can increase those straight pin barrel release barrels to any diameter I want but the thicker they are the more likely they are to autorelease on the basetube - and that malfunction could prove deadly if you were to find yourself low and slow - a la Bennett/DelSignore. The flared barrel of the Bailey does nothing but make that release more dangerous.

Side note -

I've taken the photo of the flip-locked barrel release off of my website. It gives the impression that this is a malfunction that can be accidentally induced in real life. It never has been and never will be. It took me four days just to figure out how to do it 'cause it's so incredibly counterintuitive.

If you start descending into the rabbit hole and manufacture the scenario it's only gonna be relevant for a new pilot whose bridle has wrapped. If he's struggled to screw up both his barrels he's gonna get the rope and will never do that again.

Further into the burrow - yeah, tough. Hang gliding is not idiotproof and it's not for everyone. When you're thirty feet over the field and the glider drops like a brick you don't push the bar out - even though that's the intuitive move. If you can't figure out how to rotate the pin with all the time in the world you're probably not going to be able to move the bar in the right direction to save your life in the fraction of a second you have to react during a low stall.

And - while we're on the subject - it's a whole helluva lot easier to put a Quallaby release (spinnaker shackle, brake lever) out of action than it is to flip lock a barrel. The cable free play adjustment is so critical that the difference between won't stay closed and lever bottoming out with nothing happening is spanned by a dirty look at the adjuster knurl. So how come we're not talking about that?

You take two off the shelf pieces of hardware designed to do other things at something around twenty fold the required load environments and connect them with a cable and you end up with the crap that's the core of this idiot myth that's embedded itself in our culture.

Land a couple of robots on Mars to drive around for years and send pictures and the results of geology tests back to Earth? No problem!

Develop a mechanism to reliably hold and release a loop of string? NO WAY DUDE! What have you been smoking? Everyone has known for eons that this is beyond the scope of human engineering.

If you think about things for a second or two, although some of the stuff we use may require a little extra help in a slack line situation (multi-strings, barrels), everything we use that doesn't have a spinnaker shackle at its core IS 100 percent reliable.

Anyway, following is a little release theory primer I wrote and the results of some testing I did while I was futilely waiting for JD to develop some sort of backbone...

The primary goal is to design something which will handle a high load and leggo - reliably - with minimal actuation effort.

The way things are almost always done around here the load is always about half the tow tension - a little over for two point and near exactly for one.

As discussed earlier, all of the releases used at Ridgely - save for variations of Steve's multi-string - are second class levers. The load is applied between the fulcrum (shackle hinge, pin eye) and (see following caveat) lever end.

In the sane designs the load is applied as close to the fulcrum as possible. In the Quest variation of the spinnaker shackle release the load is applied about halfway between the fulcrum and gate end.

In the curved pin barrel release (Bailey) the effective end of the lever arm is actually the middle of the lever arm.

The performance of a release is expressed in terms of a load to actuation ratio - L/A. For example...

One point tow, 200 pounds of tow line tension split between two shoulder mounted barrel releases - 100 each. Takes 5 pounds to slide the barrel clear. L/A = 100/5 = 20.

The release efficiency - L/A - is analogous to the performance of the glider itself - lift to drag - L/D. The numbers even fall into similar ranges.

The drag associated with the glider is the sum of aerodynamic and parasitic.

The required actuation force associated with the release is a function of the mechanical advantage and internal friction of the device.

I ran some tests on a variety of AT releases to determine their L/A ratios under the range of direct loading the devices experience as follows - units in pounds.

062.5 - normal tow tension
140.0 - weak link, single loop
200.0 - weak link, double loop
227.5 - shear link, 455 pound (mine)

The releases tested were:

Bailey -- curved pin barrel
wide ---- as above with a straight pin substituted
remote -- the keel mounted barrel release I use for my two point system
barrel -- my straight pin shoulder mounted barrel
shackle - Wichard 2673 spinnaker shackle - unmodified (Wallaby, Lookout)
Quest --- as above but modified to take the load perpendicular to the intended angle (zero)
Hinkel -- the sane man's cable actuated release

In addition to the above loads I tested the remote, barrel, shackle, and Hinkel at 250 and 300 pounds. The Quest configuration, however, didn't get abused beyond normal tow tension.

The averaged results were as follows with the first column being the L/A ratio and second the maximum permissible tow tension to remain within the 25 pound limit.

---

barrels:

06.2 - 0310 - Bailey
10.5 - 0522 - wide
16.4 - 0820 - remote
20.4 - 1020 - barrel

spinnaker shackles:

16.1 - 0806 - shackle
06.3 - 0312 - Quest

mission specific:

30.6 - 1530 - Hinkel

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So to summarize/interpret...

Let's take a look at those releases again ranked by performance from marginal/unacceptable to excellent above and beyond the call of duty...

06.2 - Bailey
06.3 - Quest
10.5 - wide
16.1 - shackle
16.4 - remote
20.4 - barrel
30.6 - Hinkel

(The Linknife is kinda cool - the greater the tension the happier it is. It doesn't get enough attention.)

The Bailey is junk - 30 percent of the performance of my straight pin barrel.

You drill the spinnaker shackle - you kiss 61 percent of your performance bye-bye and bring to within a hair's breadth of the Bailey. You can compensate for that with a big ugly four to one brake lever but then you need a big ugly four to one brake lever.

Swapping a straight pin into a Bailey buys you a 69 percent performance gain.

The remote barrel performs about the same as the spinnaker shackle in the range with which we're concerned. As I now configure the former and used to the latter there's a pulley which doubles the mechanical advantage so we're talking over 32:1 - that's some serious overkill.

My straight pin barrel performs well over three times what the Bailey's good for.

But - HOLY SHIT - take a look at that job of Tim Hinkel's! And that's probably gonna get a little better 'cause - if I remember right - last I saw him he was talking about using a different bronze alloy for the button which retains the lever tube which reduces the friction even further. Can't wait to get ahold of the latest prototype and get some photos up.