Kite Strings

ok thanks.
look at my drawing too, is that right ?

http://www.flickr.com/photos/61469129@N07/5595214443/

It will take few days before to read everything. It's close to be an encyclopaedia in 12 Vol !

Thanks.

If you don't mind, maybe you will accept to answer some specific questions you surely did before.

Nothing would make me happier. Well, nothing I can imagine actually happening any time soon would make me happier.

I'm convinced with your "protow" release...

Just for the record... I DESPISE the term "pro tow". There's NOTHING professional about it. It's a dangerous compromise of an ideal towing system and there's no amount of skill or experience that can compensate for it. I don't have much of a problem with people towing that way on appropriate (higher performance) gliders and have towed that way myself and would do so again - but I refer to it as one point.

...with straight pin and small and thick bridle. I will do one.

Don't do the bridle yet.

With it, do you use weaklinks on the both side too in a "1 point" and "2 points" use ?

1. Your glider MUST BE weak link protected at all times no matter what happens.

2. And what's on the tug doesn't count because you:
- can't trust those bastards; and
- never know what the front end of the towline is going to tie itself to after it comes loose.

3. Actually, it's not so much the glider that needs to be protected. What you REALLY need the weak link for is to make sure that none of your releases are overloaded.

4. The front end weak link MUST be stronger than the back end weak link because it's always inconvenient and sometimes deadly to leave a hang glider with the towline.

5. If you put appropriate Tost sailplane weak links at both ends of the towline you're covered. You won't be able to overload your glider or any of your releases (if your bridle/release system is properly configured).

6. If you properly incorporate weak links into your bridle/release you:
- don't need a (heavy) Tost weak link on the back end of the towline
- ensure that you'll be using the appropriate weak link(s) for your glider
- can configure your bridle / release / weak link system to virtually eliminate the problem of a bridle wrapping at the tow ring

Bridles...

- The primary / two point bridle MUST BE long and therefore MUST BE long enough to be capable of wrapping at the tow ring.

- As you now know, the secondary / one point bridle can and should be made short and fat enough so that it's incapable of wrapping when one end is released.

Several years ago I figured out that you could make very effective weak links by stitching two elements together - the number of stitches determining the strength. I called them "Shear Links" because the two elements shear apart at failure.

I then figured out that such a Shear Link could also be a secondary / one point bridle and called it a "Bridle Link".

You can see how Bridle Links are constructed, installed, configured in:

http://www.flickr.com/photos/aerotowrelease/sets/72057594141352219/
http://www.flickr.com/photos/aerotowrelease/8318603266/


http://www.flickr.com/photos/aerotowrelease/8306152861/

And Zack is using one of them in the photo in his last post on this thread.

Bridle Links have excellent tolerances, don't wear out or degrade, will not wrap, and are cheap and easy to make. There's no good reason not to use them.

With it, do you use weaklinks on the both side too in a "1 point" and "2 points" use ?

If you don't have a weak link on the end of the towline and you have a bridle long enough to wrap you MUST have weak links above and below the tow ring.

Do you use a specific rope friction-proof as a bridle ? or is it useless ?

Friction isn't an issue with respect to bridle material except that you NEVER want to have fabric moving on fabric. You need a smooth metal tow ring (carabiner) for your primary bridle and a thimble...

http://www.flickr.com/photos/aerotowrelease/8312737353/


...for the secondary bridle (Bridle Link) to shift and feed through. (You can also see the thimble in Zack's photo if you look real hard.)

The primary bridle - and all the material between you and the tug - MUST be low stretch so the tow can be best controlled and you don't lose an eye when something blows - as did one of my acquaintances (Mike Robertson - 1986).

Bridles are predisposed to wrapping if they:
- are thin and flexible - the way Davis makes them;
- increase in mass, thickness, and/or stiffness towards the ends - the way Davis makes them; and/or
- have other irregularities in the half you're trying to feed through.

So you want the bridle to be low stretch, braided (not twisted), thick, stiff, and uniform or smoothly and gradually tapering.

You seem to be really confident with weak link you selected.

Yes. Just as confident as the sailplane manufacturers who designate specific weak link ratings for their birds.

...I'm still scared to have weaklinks on my shoulders as it could blow with V-bridle...

GOOD! You should be. That's one of the scariest things I can think of in hang glider towing.

...in tandem...

And solo.

It should also be pretty scary NOT having a weak link below the tow ring and thus having your secondary releases (and glider) potentially exposed to virtually unlimited towline tension - but Americans have always been known for their bravery (if not their intelligence).

...(even if they are well calculate as they could be weakened by friction if you don't change them every flight).

Two solutions...
- Put an appropriate - preferably Tost - weak link on your end of the towline.
- Configure your system so that your secondary weak links aren't subjected to friction, abrasion, abuse, degradation.

About the WORST thing you can do is put a string loop weak link directly on one of your harness's tow loops - so, naturally, hang gliding being hang gliding, that's exactly how damn near everybody does it.

If you go with Option 2 you pick up a REAL SIGNIFICANT safety advantage.

I've had two bridle wraps (sloppy bridle design - my fault) under normal tension during regular planned releases. The jolt when the bridle ties itself to the tow ring is freaking UNREAL - they had to use pliers to untie one of them back at the flight line.

My primary weak link (at the top) was about 272 pounds. The secondary weak link (at the bottom) was about 320. It didn't have a PRAYER - it just VAPORIZED. So configured like that you have an almost one hundred percent guaranteed secondary emergency auto release. The tandem pilots at Ridgely reached the same conclusion.

I'm comfortable enough with my tolerances to say give it a twenty percent margin. If you're not then you can go up to a hundred percent (double on the bottom what you're using on the top). But the narrower you make it the lower the probability that you're ever going to need to go to a secondary release.

In the event of a snag I would be towed by the keel. And in this configuration I don't understand how a weak link there would instantly blow, as a normal tow tension is 15kg...

No way. You'd need more than that to roll it on a paved runway at five miles an hour. Where did you get that number from?

...far lower than the strength of the wl, except maybe by the 'jerk' of re-tension ?

YOU CANNOT AFFORD TO RISK BEING TOWED BY THE KEEL FOR EVEN A SECOND. People have INSTANTLY had their keels broken, been tucked and had their gliders broken under negative loading, and tumbled.

You don't have any mass up there. When the top end of the bridle wraps there's a big pilot with a lot of mass and inertia and a weak link at the bottom end is almost certain to blow. That's very unlikely to happen if you wrap the bottom end. Here's what Rohan Holtkamp says on the issue:

http://ozreport.com/forum/viewtopic.php?t=11591
Where to put the weaklink - the HGFA rules

Rohan Holtkamp - 2008/04/21

Once again history has shown us that this thread-through system can hook up and the hang glider remains being towed by the keel only, with the bridle well out of reach of even a hook knife. I know of just one pilot to survive this type of hook-up, took him some twelve months to walk again though.

I towed my Wills Wing HPAT 158 - VG full on, flying weight 145 kg - behind a 914 Dragonfly and measured 57 kg tow tension - 70 with the turbocharger kicked in. And when you release without pulling in the glider decelerates very abruptly and the tug does just the opposite.

So, in a "2 points" you use 4 wl, one on the apex, one on the primary release and 2 on shoulders at each end of the bridle. Is that right ?

That was right before I developed the Shear Links. Now I have a Ribbon Bridle so there's a primary Shear Link built into the top, a secondary built into the bottom, and a Bridle Link between my shoulder releases.

But the Ribbon Bridle is insanely labor intensive and I won't ever do another one.

Zack's using what I would recommend and use for myself - a sliced hollow braid Dyneema line with a string loop weak link at the top end and a Bridle Link between the shoulder releases.

Which one you will advise to change every flight?

If you're using a one G or better weak link at the top and not chewing it up with a spinnaker shackle you may not EVER need to change it. Inspect it every now and then to make sure it isn't getting fuzzed. And you'll never need to replace a Bridle Link unless it blows.

May you give me the equation to calculate the 1G weaklink with a sixty degree angle, please ?

You have a North Wing T2. Its maximum certified flying weight is 235 kg. Split that in half - 117.5. Multiply by 1.15. You want a 135 kg weak link at the top end of the bridle.

(The 1.15 you get from the secant of half the apex angle.)

Could you explain me that...

As discussed above, twenty percent is just an arbitrary minimum based upon my weak link tolerances with which I feel comfortable.

How do you manage the different weight of passengers.

Ignore them. You're ONLY concerned with the MAXIMUM CERTIFIED FLYING WEIGHT of your glider. For example...

- North Wing says that you can safely fly the T2 fully loaded at 235 kg.

- The HGMA (and/or DHV) has certified that glider to something in the neighborhood of six Gs positive loading but three Gs for sure / no sweat.

- As totally freaking clueless as USHGA is on weak links they - and the FAA - have a regulation which allows that fully loaded glider to be aerotowed using a two G weak link.

- With the glider doing its normal one G you can add two Gs of tow tension and the glider will only feel three Gs.

- If you're also pulling a hard turn on tow you could add a half a G's worth of stress to the glider but...

- Three and a half Gs isn't going to break your glider.

- If you're pulling a hard turn away from the tug on aerotow you're not going to be on aerotow much longer no matter what you're using for a weak link.

- If you were towing with the glider under its maximum certified flying weight you COULD go to a weak link over a like number of kilograms over two Gs and maintain the same safety margin.

- But one and a half Gs is a good enough figure for a weak link that's very unlikely to blow when you're halfway under control or have a reasonable shot at getting it back and is about what the sailplane manufacturers and most people who know what they're doing shoot for.

Do I have to change the 4 wl every flights ?

No. See above.

Or which margin you would accept as you seem to accept some: you usually prefer 1.5G wl and tell me ok for 1G.

I don't know what you're using for a tug or what its limitations are. Bobby Bailey doesn't have a clue what a weak link is and thus the back end of the Dragonfly is poorly and dangerously designed. The tow mast is designed to snap off when the tow tension gets to around 200 kg. If you can go to 1.5 without too much risk of getting the towline go to 1.5. If you can't get the tug capacity to over a G then there's not much point.

Actually (shame on us) we only use a 144kg tested wl on the apex...

That's pretty light. Why were you using that rating?

Hang glider people DO get away with light weak links all the time with usually nothing more than a bunch of minor crashes and a lot of clogged launch lines. But every once in a while...

...(and one more stronger on the tug side (maybe 50% stronger as I don't exactly remember (I know it's bad))...

Please find out for me. And please find out WHY they're using that rating.

If it IS fifty percent stronger that will only get you up to 0.92 Gs max loaded. I'd fly that if I couldn't do any better but I wouldn't be real happy about it.

...no different one and no more elsewhere..

If you had good secondary releases you could probably get away with doing that by relying on the tug's weak link (assuming it's on the end of the towline and not just on one end of a bridle. You can probably still get away with it as it is but I wouldn't go up on it - especially given that the fixes are so easy.

What is your opinion on a release in the apex of a V-bridle rather than the 2 releases system ?

They're junk. It's not that it's a bad idea to have the release there but unless you put a lot of cable crap in the air there's no way to actuate it with your hands on the basetube.

The people who configure and advocate for having the release there are all idiots. Peter Birren comes to mind immediately:

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

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

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

The ONLY good way to do a two point aero configuration is to have the release mechanism on the keel and the actuator in hand on the basetube.

I understood you are against carabiners.

Not in the least. They DO introduce a possibility for snagging something but I'd guess the hazard is about a billionth of a typical standup landing.

- If you're towing one point and have a faired basetube connect the carabiner to the bridle gate up to eliminate the possibility of it snagging.

- If you have a round basetube connect it with the gate up anyway.

- You can reduce stress/wear on your releases and virtually eliminate the possibility of a bridle wrap by climbing a bit just before release and then diving just prior to and during release. If you do that don't do it to the extent that you overfly the carabiner afterwards.

- Don't ever allow a slack line situation to develop.

About snagging event, which difference you see with a small carabiner and a standard ring ?

I actually don't see any difference 'cause all I've ever towed with was a standard aluminum nonlocking oval carabiner. But I think all this business about special carabiners, round rings, and homemade teardrop rings is a bunch of crap - none of these idiots are looking at the bridle design and I know for sure that's the big issue. And with a good weak link system and emergency secondary release the big issue is a total non issue anyway (except if your bridle separates from the tow ring before the tug lands and you lose it).

Does the 'top of a bottle' cut (the one which protect the wl on the apex below the ring) protect against a snag ?

I doubt it has any bearing one way or the other on the snag issue but I might be worried about it chewing up the bridle a little upon release. (Are you operating off of grass or pavement (or both)?) If I were using a weak link which stayed on the back end of the towline I'd go with Tost.

...and front wires against carabiner ?

This business about wires, bridles, releases, carabiners, and wires is bunch of totally imaginary bullshit invented by idiots who've never been around aerotowing and/or can't read, think, or look at pictures.

We have HUGE aerotow operations over here which pull off zillions of tows with really crappy tug and glider drivers, instructors, equipment, and procedures. The carabiner NEVER gets near the wires unless there's a major slack line event. And major slack line events are rare as hens' teeth and totally avoidable if both pilots are awake. And if you get into a major slack line event all bets are off anyway and the carabiner might not be terribly high on your list of things to worry about.

I have to organize a comp in my flatland and we need a quick system to catch bridle of each pilot..

Use a carabiner and only fly pilots with enough common sense to avoid flying into thunderstorms.

...(sorry for the win-win consideration).

No problem. We're moving fast in the right direction and I'm very happy. Just do me and yourself a big favor and don't ever talk to any of those assholes again. (And I can give you a really long list of other assholes never to talk to as well.)

I'd like to accept your help to work on setting an easy primary release as VG system but I need more time than actually..

Keep looking at my photos and forget the stuff inside the basetube - that's a lot of work and isn't really important. The rest is pretty easy.

...look at my drawing too, is that right ?

Yeah, all those numbers are fine. BUT...
- Don't even THINK about "a snag with the under bridle part". You can't afford to have that happen much more than a sidewire failure.
- There's no such thing as "a snag with the small V-bridle" - we can totally design that out of the equation.

Thanks again for participating and keep the questions coming. That's the primary raison d'etre for this forum.

Tad Eareckson wrote:Rather nasty bend in your starboard nose wire.

Ha...I love having a wide angle lens but it has its drawbacks. Besides the fisheye distortion, it makes everything look small.

Tad Eareckson wrote:Where are the videos of the one point tow and wangs?

It was too rowdy for my first time trying out one point, and I was too busy trying to find lift to do any wangs. But why are you interested in me towing one point anyway? I'm not crazy about the idea and only considering it because I don't have a suitable two point release for foot launching.

Tad Eareckson wrote:Is there any way you can Photoshop out the hook knife?

Hey, you're the Photoshop expert.

Tad Eareckson wrote:

Zack C wrote:...three flights, no issues.

Which is another way of saying that Matt's release worked OK and my weak links held and my bridle didn't wrap.

Yes, but maybe I spoke too soon...

Everything did fine in flight, and everything was fine when I put it back in my equipment bag (not my harness bag but a separate bag where I keep my radio/vario/cameras/mounts and the like). When I removed the bridle link from my bag today, however, I found that the leech line strings had been pulled apart a bit on one side and the floss stitching was up to the strings. I pulled the floss out to tighten it but quickly realized it was left with only three stitches on that side.

So I can't use it again until I fix it, and I don't think I can fix it without replacing the floss.

I'm not sure how it happened...it's not like it was caught on anything and I pulled it. But this was only after one day, which makes me nervous about these things, especially considering the potential consequences of the bottom weak link breaking before the top.

I think the fairings are a great idea and wish they were compatible with towing two point.

Tad Eareckson wrote:Were any of the other kids the least bit interested?

Not as far as I could tell. No one mentioned anything to me either on site or in response to the video of the day's flying I posted.

Tad Eareckson wrote:I couldn't get ahold of anything better than the 800x600 you embedded.

Yes, I forgot I reduced the image because it looked too big embedded. Unlike Flickr, Photobucket doesn't let you embed any size other than the original. I've emailed the original to you. By the way, I uploaded it to Flickr just to see what it would do and it reduced it to 1024x768, which isn't bad. Maybe you should try re-uploading some of your images to see if they'll be bigger.

Tad Eareckson wrote:I'm not crazy about it [LMFP release] but you could do a lot worse. (That's what Zack's using.) You could also do a lot better and much cheaper from Joe Street in Ontario[...]

So why is Joe's release better than Lookout's? So far I've been pretty happy with the Lookout release. Releasing is effortless and instantaneous but I've never had an issue with triggering it prematurely. Here are my releases from Saturday (password = 'red'):
http://vimeo.com/22009433

Tad Eareckson wrote:The tow mast is designed to snap off when the tow tension gets to around 400 kg.

Is that right? I thought it was more like 400 lbs.

Zack

Besides the fisheye distortion, it makes everything look small.

Yeah, I was pretty impressed by how high you'd gotten with all that runway left over.

It was too rowdy for my first time trying out one point...

Oh. Between the T-shirt and the boring looking clouds I was figuring it was pretty smooth.

...and I was too busy trying to find lift to do any wangs.

'Tis nobler to thermal than to wang and I'm a fan of keeping up the fight down to a hundred feet but sometimes it's obvious that there's no hope and you oughta have a little fun.

But why are you interested in me towing one point anyway?

1. You wanna have lotsa different stuff in your logbook. It's like merit badges. You can say, "Yeah, I have that skill." - and actually have that skill.

2. There's a small possibility that you could find yourself inadvertently towing one point for a bit. I almost think that a one point flight oughta be a requirement for an AT signoff. (Makes a helluva lot more sense than the goddam spot landings - and it's a helluva lot less dangerous.)

3. It's not that B an FD. Gliders like that are towed one point all the time. I'm sure you'll be surprised at how easy it is.

4. Back during the last ice age when we first generation folk were introduced to aerotowing the tugs were too fast, the gliders were all too slow, it was all foot launched one point, and we all lived anyway.

Yes, but maybe I spoke too soon...

No, don't panic, everything's fine.

1. The Bridle Link Strength Stitching is at one or both ends of the quadruple overlap areas to keep it away from the thimble or tow ring.

2. Strength Stitching runs don't/can't drop below five 'cause then things go nonlinear. The runs start pulling through instead of blowing - and it all needs to blow for good predictability.

3. That's a Number 8 - one up from the bottom of the range.

4. For 7, 8, and 9 I can't do 5+2, 5+3, and 5+4 'cause the first two would still by fives 'cause the two and three runs would just pull through without doing anything and the last one wouldn't be up to snuff either.

5. So for those ratings all the Strength Stitching is on one side and there's a three pass on the opposite just to keep things neat. It ups the strength a little but pretty negligibly. And you could pull it out completely without having any appreciable effect on things.

6. Starting at 10 I can do 5+5, 5+6, 6+6, et cetera.

7. The stitching WILL shift a little when it's loaded. Ignore the distortion on the Strength Stitching but go ahead and pull the cosmetic three pass back like you did.

8. If a floss end is protruding from an outer (top or bottom) run of the leechline you KNOW it hasn't accidentally pulled through - it's physically impossible for it to end up looking like that. So if you see both ends of both lengths of floss so protruding you know you're OK integrity-wise.

Not as far as I could tell.

Shit. Not looking good for a forming a Columbus Pigs' Choir either. "Why bother? My Bailey and Greenspot have always worked JUST FINE. If it ain't broke... And besides, I'm not being a TEST PILOT for an UNPROVEN SYSTEM."

Maybe you should try re-uploading...

Even if I could... In Flickr you can't reload or replace something with a new edit. You have to trash the original - AND ITS URL - unless you want duplicates all over the place. And I have links to specific photos all over the goddam web - mostly in fora from which I've been banned.

I tried to save those bastards bandwidth by cropping out every pixel that wasn't hardware and they screwed me over anyway. (No good deed...)

So why is Joe's release better than Lookout's?

I'm actually not POSITIVE it is. I mainly don't like Matt's 'cause it's inefficient, unnecessarily complex, ridiculously overbuilt, and correspondingly expensive (and it's Matt's). But it appears to work well and I'd predict that it's gonna do a whole lot better than all that ass covering stuff in the owner's manual indicates. But I'm still never gonna be completely happy until I can get you to build something in.

Here are my releases from Saturday...

Notice how SMOOTHLY the bridle's feeding out through the tow ring? (Actually, you CAN feel irregularities pretty easily.)

I thought it was more like 400 *POUNDS*.

Oops. Forgot to divide by two before going to print. (A certain failed Mars probe is coming to mind.) Thanks for the catch. If I start putting out too much potentially deadly misinformation I'm probably gonna get sued for copyright infringement by USHGA, Wallaby, Quest, Lookout, and/or Sport Aviation Publications. I went back and fixed it just in case.

Damn I wish that we were all on the same system page - preferably theirs. It would also make it easier if weak links were in kilograms instead of decaNewtons. Yeah, I realize there's a difference between mass and force - but as long as we're doing most of our towing on this planet...

Tad Eareckson wrote:Between the T-shirt and the boring looking clouds I was figuring it was pretty smooth.

Around here I always fly with a T-shirt if it's 80+ on the ground. This time of year we generally don't get higher than 4000' or so. The highest we ever get (June-August) is ~7000' and then it's always hot as hell on the ground so it ain't too bad at 7K.

It wasn't that rowdy, but I want it to be smooth my first time. I know, it's not a BFD...

Tad Eareckson wrote:No, don't panic, everything's fine.

While it's good to hear I'm just trippin', I'm no less confused.

I was assuming the number of stitches would be the same on each end because it seems to me that the force on the lower end of the primary bridle will be split 50/50 to each bridle link end and thus if one side had fewer stitches than the other it would blow at a lower force than the other. What am I missing?

While on this topic, when I asked about testing the breaking point of doubled bridle links, you said

Or just think of the Bridle Link as a rope that breaks at X pounds. If you double it / fold it in half you can lift 2X pounds.

I didn't really follow you. How is this different from using a loop (two strands) of weak link material? You've verified that this doesn't double the strength.

I tried to save those bastards [Flickr] bandwidth by cropping out every pixel that wasn't hardware and they screwed me over anyway.

I think the explanation to your Flickr woes is here:
http://www.flickr.com/help/photos/#2795204
See 2) - you said when you uploaded them they didn't allow 1280. They give you a hack workaround but it changes the URL, which I agree is a bad thing (pretty crappy on their part considering they still have the originals). It looks like you can replace them with a $25/yr pro account. It may be possible to have a pro account for a year, replace your photos, and then downgrade to a free account after the year's up without losing them.

When I was looking at your photos earlier, I thought it was a shame they were of such low resolution given the amount of effort you put into them. I didn't realize they weren't always that way.

Zack

Around here I always fly with a T-shirt...

I'd still go with a long sleeved T and gloves 'cause I'm scared of cancer (it - and the chemo (and surgery)) did a real number on me in '83 and you're never entirely sure what you're gonna slide into at the other end of the flight.

I'm no less confused.

Lemme do this one out of order...

How is this different from using a loop (two strands) of weak link material? You've verified that this doesn't double the strength.

The breaking strength of a line is determined with the line straight (I think they use Chinese finger trap devices at the factory) and ALL of the fibers equally/evenly loaded.

If you bend the line the fibers on the outside of the turn are stressed more and the ones on the inside aren't doing their share so the line's gonna blow at a lower tension.

Knots ALWAYS involve sharp bends and - while some are better than others - you generally figure on throwing away half the strength.

Splices are a lot kinder and you can retain close enough to the breaking strength to call it the breaking strength. Put two eye splices in the ends of a length of two thousand pound hollow braid Spectra and you can lift very close to two thousand pounds with the line straight (undoubled).

(Yeah, the ends are making fairly sharp turns but the line's doubled there so it's a divided by two / times two sorta thing.)

(Also... I can get a lot closer to breaking strength by stitching leechline than by tying it but the stitching itself forces fibers to go out of their way a little bit and the leechline WILL blow at the stitching.)

The wider the radius of the bend the more fair the outside/inside load distribution is. So if you ran the spliced Spectra through a large diameter pulley and hooked the ends to your load you could lift very close to four thousand pounds.

With the 130 pound Greenspot, as much as the flight parks would like to pretend otherwise, you're using knots - a Fisherman's Knot and a (Double) Lark's Head. And when you install the loops on the hollow braid bridles we use you chuck about half the breaking strength - so two strands divided by two equals 130.

And if the bridle's a one point (in which the apex angle is very acute) it will blow at 260 pounds of tow tension (if you're lucky).

Note:

1. You can make the bend in the two thousand pound hollow braid Spectra (at the tow ring) as sharp as you like (short of over a knife edge) without reducing the blow tension 'cause there's no freakin' way the Spectra's gonna blow before the Greenspot.

2. Likewise with the Bridle Link. Four runs of 350 pound Dacron leechline are NOT gonna blow before the few stitches of dental floss holding them together.

What am I missing?

You're thinking of it as if it were a Spectra bridle with a loop of 130 Greenspot on one end and a loop of 200 on the other. It doesn't work that way. It's an optical illusion.

In that configuration the materials - 130, 2000, and 200 - are in SERIES. You don't get:

130+2000+200=2330*2=4660

The 2000 and 200 are irrelevant. The 130 is all that matters. The whole bridle could be a long loop of 130. You get:

130=130*2=260

In the Bridle Link the stitches are in PARALLEL. For a Number 13 you DO get:

18+18+18+18+18+18+18+18+18+18+18+18+18=234*2=468

- no matter where those stitches are in the Overlap.

I was assuming the number of stitches would be the same on each end...

No.

For starters... It happens that your Bridle Link for one point is a Twelve - six port plus six starboard. If it had been the next rating up - see above - it would be six port plus SEVEN starboard.

...because it seems to me that the force on the lower end of the primary bridle...

Throw out the Primary Bridle and tow one point with the Number 13 to simplify things.

...will be split 50/50 to each bridle link end...

YES. (And because the tow ring is free to slide on the bridle (link).)

...and thus if one side had fewer stitches than the other it would blow at a lower force than the other.

NO.

As above, the stitches are ALL loaded EVENLY and will ALL blow SIMULTANEOUSLY no matter where they are.

My port/starboard distribution is 6+7. It could be also be 5+8 or 0+13. Or 8+5 or 13+0. (Or, just to make things confusing, 3+13 or 13+3 because - as previously discussed - three equals zero because a three run will pull through rather than blow and have little effect on the rating.)

It doesn't matter if the stitches are evenly split, unevenly split, all at one end, all at the other end, or evenly spaced over the entire length of the Overlap.

1. Unclip the snap shackles from your harness.

2. Clip one snap shackle to a rope coming off a heavy tree limb.

3. Clip the other end to a big heavy bucket.

4. Start pouring sand into the bucket.

5. When the load starts approaching 234 pounds make sure your foot's not under the bucket.

Does it matter how or where those thirteen stitches are distributed?

6. Unclip the snap shackles and install your spare Number 13 Bridle Link between the Barrel Releases where the first one used to be.

7. Clip a carabiner to the rope coming off the limb.

8. Clip both snap shackles to the bucket and engage the carabiner (à la tow ring). (You'll need a couple of buddies to help lift the bucket.)

How much more sand do you think you can add to the bucket before things get violent?

Does that work for you? (If it makes you feel any better I had the EXACT same difficulty/confusion when I was developing this stuff. (And when I first was looking at Tost weak links it took me a while to deprogram and understand that a hang glider weak link didn't hafta go on the end of a bridle.)

Flickr...

Thanks, that explains a few things.

They're still lying.

When I first started using them I didn't find anything about resolution limitation and started uploading at 2816. They didn't chop them down to 1280 - they chopped down to 1024. So I started chopping them down to that before I sent them.

And later when I'd accidentally send one at full they'd still chop to 1024.

1024 wasn't bad - I could live with that well enough. 640 totally sucks.

...I thought it was a shame they were of such low resolution given the amount of effort you put into them.

Yeah. Looks like Moore's law may have started heading back south.

I may just leave that site alone 'cause of the URL issue, see what other options are out there (I haven't really checked out Photobucket or anything else yet), and put a note on Flickr to redirect anyone who's interested in something more than a quick glance.

http://www.hanggliding.org/viewtopic.php?t=21242
Mouth Release - Where / How can I get one ???

Chad May - 2011/03/28 16:57:31 UTC

Update...

Hey gang, CinCas (Linas) was very kind to sell me one of his mouth releases... and I haven't had a chance to test it yet, but I think I will youtube a video of its operation and forces involved etc.

I haven't heard from Aeros or anyone on the Oz Report about this, but something might turn up.

From my initial toying with the Russian-made release from Linas, it seems very easy to both hold in your mouth and to easily release and spit out. Someone put some thought into its design, as deceptively simple as it looks.

Well Chad... Steve and I put a lot of thought, time, effort into our designs and came up with something that's definitely lighter and cleaner, at least as simple, and probably cheaper and a lot more powerful than the Russian job - but hardly anyone is the least bit interested.

To give credit where it's due... The Russian job IS gonna be better for slack line - you can do it no hands whereas ours require one - but that's not enough of an offset to make me the least bit inclined to jump ship or recommend it over a Four-String - or Remote Barrel.

We could put our money together and either copy it or just ask Linas to contact the Russian gentleman and have him ship us over a box.

More to come...

Jim Gaar - 2011/03/28 19:16:23 UTC

Keep us informed!

Why? So you can piss all over it and tell people how dangerous it is to use anything with more parts than a webbing loop, a fat barrel, and a bent pin?

Or do you only enjoy pissing all over stuff that comes from individuals inside the of US and outside of the Flight Park Mafia?

Chad May - 2011/04/08 06:30:13 UTC

Hi y'all,

Tom Clark, owner of DeimosPG.com (and HG too) was very kind to contact Aeros (he's listed as a dealer) and inquire about mouth releases... and they have no plans to sell them. I guess they did at one time?

Well, Tom graciously offered to make a release or maybe a few if we ask him:

DeimosPG.com

I would send him mine for a pattern, but I kinda need it. I'm still waiting to give it a try, weather's been windy last few weeks.

You pretty much only kinda need it if you're gonna tow one point. If you give it a try towing two you can kill yourself pretty easily.

Also, I'm hopeful that a 3 or 4 string cascade style release as was posted on the Oz Report might actually work well.

1. It NEEDS to be a Four. Three doesn't do it - as I've verified on the ground and Steve's verified in the air.

2. There's no "might" about it. It DOES actually work well (if you don't deliberately sabotage it the way Davis did). It's been flying for over six years.

You hold a string in your teeth... if you let go, it threads itself back through the cascading loops and hopefully nothing wraps.

Do us a favor and drop the "hopefully".

And Linas has the email address of the Russian fellow who made his.

I wish the release actuator cable on mine was a little longer.

Glad to hear that's a problem on that unit. Sounds like somebody screwed up a little bit. But, what the hell, you really only need this thing for the first couple hundred feet and I'm also thinking you can probably shorten whatever it is you're using to mount it and so compensate. (You could probably also redo/replace the cable assembly.)

The way I do my Four-String there's a one time adjustment issue but I should probably be a little less anal and make them all a little bit longer for a universal - rather than custom - fit.

With the Remote Barrel you can very easily install whatever 205 leechline lanyard you want and the length is in no way critical anyway.

Red Howard - 2011/04/08 14:12:41 UTC

Campers,

Wanna laugh? Look up Deimos in your Funk and Wagnall's.

Yep, that's exactly what it's there for.
---
Edit - 2012/11/23

Oops. It actually NEEDS to be a Three.

http://www.kitestrings.org/topic61.html

Blue Sky

Aerotow Release Primary

Aerotow Primary Release --Moyes stainless spinaker release with velcro and attachable bicycle brake release handle

After the second failed attempt to release, I thought about releasing from the secondary, but before I could move my hand the tug stalled and started to fall...

I just kept hitting the brake lever for a few seconds in WTF mode, and the instructor used the barrel release.

Robin's own release failed to release. Do not use a 'Wichard' or 'spinnaker' release directly connected to a string or rope. This type of metal release has a metal knob on the opening arm that a rope will catch on, even when the release is activated and open.

I tried to release but my body was off centered and could not reach the release.

When Jim got me locked out to the right, I couldn't keep the pitch of the glider with one hand for more than a second (the pressure was a zillion pounds, more or less), but the F'ing release slid around when I tried to hit it.

$175.00

Yep. Spend the big bucks so you know you're getting something good.

Barrel Release

Standard barrel release, can be produced in a variety of styles

REALLY? Different STYLES!!! Styles are always SO important to me! Can I get different shaped pins?

The barrel release wouldn't work because we had too much pressure on it.

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

I so do love the curved ones. And can we get them with different colored webbing?

$18.00

Platform Release

(Three-Ring Tow Release by Blue Sky) The three-ring tow release by Blue Sky is a soft yet strong release designed to bypass the pilot to the carabiner to avoid added stress on the harness. Just route the main straps through Platform towing loops up to the Carabiner.

Yeah, keep that extra stress off the harness. I've had six or seven close friends killed because their harnesses were torn apart while they were connected just to the platform loops.

This simple design has been proof tested over the years to be strong...

1. How many years does it take to verify the strength of a design?

2. Any way we can get that in POUNDS instead of YEARS?

3. Or did you just skip the bench testing, throw it up on a bunch of gliders, and never have one blow?

5. Just how strong does it need to be anyway?

...and very reliable.

Very reliable. What the hell does that mean?

Bill Bryden - 2000/02

The rapidity of the lockout was absolutely stunning to those observing the event. The glider went from being banked approximately 25 degrees and angled roughly 45 degrees to the towline, to being rolled over and pointed down in less than two to three seconds after the rollover.

If you can get to it in time.

1990/03/29
Brad Anderson
24
Novice
Flight Designs Javelin
platform tow
McMinnville, Oregon
head injury, ruptured thoracic aorta

"Strong novice" pilot with a lot of flying and some truck tow experience. With instructors present launched and rose to fifty feet over truck. Pushed out hard enough to release and continued to push out after release. Whip stalled and dove into the ground. Died instantly.

1990/07/05
Eric Aasletten
24
Intermediate
2-3 years
UP Axis
platform tow
Hobbs, New Mexico
fatal / head

Reasonably proficient intermediate with over a year of platform tow experience was launching during tow meet. Homemade ATOL copy with winch on the front of the truck. Immediately after launch, the glider pitched up sharply with nose very high. Apparently the angle caused an "auto release" of the towline from the pilot, who completed a hammerhead stall and dove into the ground. Observer felt that a dust devil, invisible on the runway, contributed or caused the relatively radical nose-up attitude. Also of concern was the presumed auto release which, if it had not occurred, might have prevented the accident. Severe head injury with unsuccessful CPR.

You're not letting guys fly at Manquin with the release lanyard on their wrists, are you? (Rhetorical.)

Shorter mains can be easily changed for Aerotow purposes.

2006/01/19
James Simpson

Then the radical actions continued and the glider went upside down and the wings folded. From 500 feet the glider tucked and spun. The pilot got the parachute out, but it did not open in time to stop the impact.

The rope looped around the side wire and formed a knot.

One of the things that interests me about this accident is that it highlights one of the potential problems of the Windtech type tow release. These releases are really difficult (if not impossible) to release with one hand if there is no tension on the tow rope. You need the bridle to be under tension for the release string to remove the pin. It strikes me that if you have enough slack in the rope to wrap around your wing wire there is probably insufficient tension to release even if you wanted to.

Yeah, use it for aero. These things make SUPER aerotow releases.

$75.00

Aerotow Release Secondary

Simple barrel release with v-bridle complete

I have never had a lockout situation happen so quickly and dramatically and had no chance to release as I have always thought I could do.

Yeah Steve, as long as it's SIMPLE we're definitely good to go - in hang glider towing it doesn't matter whether or not something actually WORKS or can be gotten to when the shit hits the fan.

$33.00

Not bad for five bucks of materials and one and a half for labor.

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

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

Bill Moyes argues that you should not have to move your hand from the base bar to release. That is because your natural inclination is to continue to hold onto the base bar in tough conditions and to try to fly the glider when you should be releasing.

Well gee, OBVIOUSLY then all you need to do is overcome your natural inclination! It's all PSYCHOLOGICAL!!! And all this time I've been thinking that it would further compromise your control in an already critical situation.

I'm willing to put the barrel release within a few inches of my hand.

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



You're not a real quick study, are you Davis? That's OK, I'm really willing for you just to put the barrel release within a few inches of your hand too.

Et tu, Boris?

Go to Chad's thread:

http://www.hanggliding.org/viewtopic.php?t=21242
Mouth Release - Where / How can I get one ???

on bite controlled releases.

Post 18, from CinCas. He has a couple of links to photos...

http://www.e1.ru/fun/photo/view_album.php?id=32439

Look what this guy's using to make his barrel releases. Kinda makes you wonder a bit about how much testing he's done on his bite controlled job and what kind of load capacity it has.

Just when you think you've found a geographical pocket of intelligent life...

http://www.e1.ru/fun/photo/view_pic.php/p/acccea05c2c064ce38c706aa8f799ab4/view.pic


http://www.e1.ru/fun/photo/view_pic.php/p/83afa5093131f9b914851b8c00b36f91/view.pic