Weak links

[Tad Eareckson]

Nobody - 2012/08/12 06:36:18 UTC

Lisa and Tracy are smart enough to know that they don't need to be competent.

I think that - just like his buddy Trisa - he's smart enough to know that, in hang gliding, he can say any outrageously moronic thing he feels like and it will have no detrimental impact whatsoever on his standing.

[Steve Davy]

HANG GLIDING FOR BEGINNER PILOTS
By Peter Cheney
Published by Matt Taber
Official Flight Training Manual of the U. S. Hang Gliding Association

Flight Tip:

One of the biggest dangers in towing is the lock-out. In a lock-out, the tension of the line overpowers the pilot's control authority, and the glider rolls hard to one side. If the pilot fails to correct, the glider may dive and roll to the ground.

Lockouts usually happen when a pilot allows the glider to roll too far off heading, so that the tow line is pulling the glider at a sharp angle.

Lockouts can be prevented by using good technique, light tow pressures, and appropriately-sized weak links--if you get too far off heading, and a lockout begins to develop, a proper weak link will break and release you from tow.

And never tow without an observer!

[Tad Eareckson]

I've been curious about the contents of that book for several years. Wish I had read it before I allowed Matt to con me into driving down there so it would've been a lot cheaper/quicker/easier to discover what a lying piece of shit he is.

I really hate to spend money on more crappy hang gliding fiction - I've already got enough Hang Gliding magazines and Pagen books - but I guess I better get on Amazon and pick up a used copy. Hopefully I'll be able use it to do enough damage to Matt to make the twenty-five bucks worth it.

[Steve Davy]

HANG GLIDING FOR BEGINNER PILOTS
By Peter Cheney
Published by Matt Taber
Official Flight Training Manual of the U. S. Hang Gliding Association

Weak links: As in all type of towing, it's crucial to have a correctly-sized weak link in the line.

Why is it crucial to have a correctly-sized weak link in the line?

The weak link is a specially-calibrated piece of line that is placed at the end of the tow line-if the line tension gets too high for any reason, the weak link will break and release you from tow.

How do you calibrate the weak link?

Weak link or rope breaks at takeoff aren't uncommon, especially with aerotowing, where the initial pull required to get the glider moving on soft ground may apply extra strain. If you experience repeated weak link failures, you and your instructor should discuss using a stronger weak link.

You have to experience repeated weak link failures then you and your "instructor" should discuss using a stronger link. Got it.

[Steve Davy]

HANG GLIDING FOR BEGINNER PILOTS
By Peter Cheney
Published by Matt Taber
Official Flight Training Manual of the U. S. Hang Gliding Association

Michael Robertson on the Golden Rules of winch towing:

The key to safe winch towing is what I call the Golden Rules. Here are some of them:

The tow pressure should be light at launch, the weak link needs to be light, and there needs to be an observer capable of terminating the tow always watching the pilot.

If you're launching off the ground, use a launch dolly. Use a proper checklist. Fly only with quality equipment and highly experienced people. Fly only in conditions you can handle, and at sites with lots of room to launch and land safely.

If you follow the rules, towing has the potential to be even safer than foot-launched flying... Problems arise when people get gung ho, or when they get lulled into complacency. Towing shouldn't be taken lightly.

One of the biggest problems I see is high tow pressures. If you keep the pressure light, you have less force to deal with, and it's more forgiving. Once you're well clear of the ground, you can go ahead and turn the pressure up if you want, but down low, keep it light.

Michael Robertson operates High Perspective Hang Gliding and Paragliding, in Ontario, Canada. Michael is known as the creator of the Charts of Reliability, a system of risk evaluation and management.

[Steve Davy]

HANG GLIDING FOR BEGINNER PILOTS
By Peter Cheney
Published by Matt Taber
Official Flight Training Manual of the U. S. Hang Gliding Association

Glossary of Hang Gliding Terms

WEAK LINK - section of line used in hang gliding towing systems. Breaks at a specified load to protect glider from gusts and overloading.

[Tad Eareckson]

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

Mike Lake - 2012/08/14 18:11:23 UTC

No big deal as long as you don't hit the ground, something I have witnessed on a few occasions.

Paul Hurless - 2012/08/14 18:13:13 UTC

That's true of any kind of launch. Failing to be ready to immediately land if a weak link breaks is a very basic pilot error.

This is a load of crap cooked up by the Flight Park Mafia...

http://ozreport.com/forum/viewtopic.php?t=24846
Is this a joke ?

Jim Rooney - 2011/08/26 02:44:10 UTC

The "purpose" of a weaklink is to increase the safety of the towing operation. PERIOD.

...and eagerly gobbled up by total morons like Paul.

Virgin 130 pound Greenspot can blow on ANY medium and up weight glider at ANY time - but, of course, is most likely to blow when the glider's hit by something.

And we're supposed to be able to pull off safe landings from any situation - thermal, crosswind gust, lull, roll, mush, stall - from still having the dolly underneath us on up while the aerotow parks are teaching people how crucial it is to be well prepared for landing at two hundred feet.

If this crap that Paul's dutifully regurgitating had the slightest legitimacy to it, Dr. Trisa Tilletti would've written the rating requirements...

The United States Hang Gliding and Paragliding Association, Inc. - 2012/06/20
Standard Operating Procedure
12. Rating System
02. Pilot Proficiency System
12. Hang Gliding Aerotow
-A. Aerotow

05. The candidate must also demonstrate the ability to properly react to a weak link/tow rope break simulation with a tandem rated pilot, initiated by the tandem pilot at altitude, but at a lower than normal release altitude. Such demonstrations should be made in smooth air.

...as such:

05. The candidate must also demonstrate the ability to properly react to a weak link/tow rope break simulation with a tandem rated pilot, initiated by the tandem pilot at a maximum altitude of twelve feet. Such demonstrations must be made in gusty crosswind conditions.

That's true of any kind of launch.

Total BULLSHIT. When you have the kind of stall situation typified by a lot of weak link failures at a slope launch there is VERY RARELY a NEED or OPTION to LAND. Just ask Eric Thorstenson...

desbi001 - 2012/09/30

Oh and, by the way, two days ago Eric moved his left fourth toe!

...if you don't believe me.

In REAL aviation a weak link failure on takeoff...

FAA Glider Flying Handbook

TAKEOFF EMERGENCY PROCEDURES

The most common emergency situations on takeoff develop when a towrope breaks, there is an inadvertent towrope release, or towplane loses power. There are five planning situations regarding in-motion towrope breaks, uncommanded release, or power loss of the towplane. While the best course of action depends on many variables, such as runway length, airport environment, and wind, all tow failures have one thing in common: the need to maintain control of the glider.

...is an EMERGENCY.

But then we had Donnell come along 32 years ago and tell everyone that these emergencies were just routine events critical for the operation of a safe towing system - and that message has engulfed hang gliding like some wildfire/cancer hybrid.

[Tad Eareckson]

http://www.hanggliding.org/viewtopic.php?t=27505
Is hang gliding too difficult to learn

Davis Straub - 2012/11/15 07:20:45 UTC

Hang gliding is easy to learn, But it may be difficult to find, go to, and stay at a hang gliding school where it is actually easy to learn to hang glide.

michael170 - 2012/11/15 09:05:18 UTC

Easy to learn, yet you still can't figure out how to stay on tow, Mr. Pro-toad.

http://www.youtube.com/watch?v=TaVg_bzK3Aw

Oops...

2012/11/15 14:37:33 UTC - Sink This! -- Craig Hassan
2012/11/15 17:57:17 UTC - Sink This! -- Paul Hurless

Looks like you got a couple of the 130 pound Greenspot zombies pissed off.

Jim Gaar - 2012/11/15 16:54:43 UTC

Ahh a listhole post AND with facts that back up the post's listholyness!

You spelled listholiness wrong.

Looks to me like on that first tow Davis was in perfect position to handle the early release...

- It wasn't an early release - asshole.
- Yes. He was in SUPERB position. But would you expect anything less after all the practice he's had?

...that he got for reasons that a listhole would not be able to understand...

I think he understands as well as anybody else in this sport...

http://ozreport.com/forum/viewtopic.php?t=24846
Is this a joke ?

Davis Straub - 2011/08/28 15:26:28 UTC

Then again, Russell Brown had us double up behind him after six breaks in a row at Zapata. We couldn't figure out why we had so many breaks so quickly. Maybe just coincidence.

Obviously just another coincidence.

What I see occurring comes with experience and good instruction which it appears listholes lack!

Yeah. We must teach Michael to:
- install on his bridle a loop of fishing line which blows just off the cart every other tow to increase the safety of the towing operation
- get the good instruction and experience to deal with it when it increases the safety of the towing operation.

Otherwise...

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

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

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

...things can get pretty ugly.

Every pilot gets into this situation on occasion.

Yeah.

http://ozreport.com/forum/viewtopic.php?t=27494
The exciting bits

Jim Gaar - 2012/04/27 03:34:28 UTC

Weak-links break! They are supposed to...we are ready for that. It's what we do.

It's inevitable. It's what this sport is all about. It's what we do.

Sailplaning though - for reasons no one can fathom - is a bit different...

Dr. Trisa Tilletti - 2012/06

You and I have flown sailplanes for almost as long as we have flown hang gliders. We own two sailplanes and have two airplanes that we use for towing full-size sailplanes. In all the time that we have flown and towed sailplanes, we have not experienced or even seen a sailplane weak link break.

They just go flying when they want to. It's what THEY do.

Being ready and capable to handle these situations with ease, is what we strive for.

Yeah Jim...

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

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

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

We're ALWAYS striving for it.

http://www.youtube.com/watch?v=eTKIAvqd7GI

Move along now...

Pigfucker.

Davis Straub - 2012/11/15 17:41:58 UTC

Thanks for linking to my video.

I don't think we'll ever get tired of linking to your video, Davis.

And I never got tired of posting this photo:



The two of them go together so well. Too fucking stupid and incompetent to equip yourself to be able to either stay on tow when you want to or get off tow when you need to.

Davis Straub - 2012/11/15 17:58:47 UTC

The video shows me launching not with a pro tow...

- He didn't say it did.
- There's no such thing as "pro tow" - it's a term used by and for assholes.
- What the hell does your bridle configuration have to do with anything?

...but with a three point tow (off the shoulders and off the keel) with a V-bridle.

It's TWO point and it's off the PILOT and GLIDER.

This is after I fixed the position of the keel connection after the 2012 Rob Kells Meet at the Florida Ridge.

Fascinating. So what the fuck does that have to do with anything?

As I recall the weaklink going to the release at the keel snapped.

No shit.

Davis Straub - 2011/07/31 17:55:25 UTC

To break under load before the glider does.

Good thing it broke before the glider did.

The launch location is Dunellon.

Fascinating. So what the fuck does that have to do with anything?

The second launch shown there came off without a hitch.

Must've been because you didn't have another coincidence.

Davis Straub - 2012/08/13 18:08:42 UTC

Used to do 130 lbs. Now do 200 lbs.

Or did you replace the 130 pound loop of 130 pound Greenspot with a 200 pound loop of 130 pound Greenspot?

[Tad Eareckson]

Tracy Tillman - 2012/10/17

130 lb Single Loop Weak Link Tests on V-Bridle

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


Hang Glider aerotow weak link tests using Pre-Tied and Wrap-and-Tied single-loop130 lb IGFA green spot dacron line

---

Weak Link Tests at Cloud 9
Single Loop on Polypro V-Bridle
130 lb. Green Spot Dacron Line
260 lb "Nominal" 1G Weak Link
October, 2012

---

Weak Link Tests at Cloud 9

6 Tests: Wrap and Tie Single-Loop Weak Loop
vs.
6 Tests: Pre-Tied Single-Loop Weak Loop

---

Wrap and Tie Single Loop
130 lb IGFA green spot dacron

= 260 lb. "Nominal" (not actual) 1g weak link

---

Pre-Tied Single Loop
130 lb IGFA green spot dacron

= 260 lb. "Nominal" (not actual) 1g weak link

---

5/16" Dia. Polypro V-bridle Test Configuration

---

100 lb Round Scale Check

---

I'm conducting weak link tests of one hundred and thirty pound Greenspot Dacron line material to compare the strength of a Wrap and Tie versus Pre-Tied weak link.

Here's an example of a Wrap and Tie weak link.

I cut about twelve inches of material, wrapped it around a quick link about six times, tying the ends together with three Overhand Knots, and then pulling on a center loop, pulling it tight, and isolating the knots as much as possible from the loop itself.

For testing purposes I'll use two metal five sixteenths diameter quick links, which is the same diameter as the polypro bridles we use here at Cloud 9.

I'm using metal quick links to reduce as many variables as possible so we can really focus on the nature of the knot and the material itself when comparing a Pre-Tied versus a Wrap and Tie weak link.

Here's an example of a Pre-Tied weak link. It's made, again, from a hundred and thirty pound Dacron line material and a loop is produced using a Grapevine Knot and then it's attached to the quick link using a Lark's Head. As before I'll be using two metal quick links for testing purposes.

And then additionally for all tests I'll be placing a loop of bungee cord in between the two quick links to help reduce the backlash reaction after the weak link breaks.

Here you can see the test configuration using the five sixteenths polypro V-bridle configured with about the same angle that's used with an actual V-bridle on a hang glider.

The round scale has been calibrated prior to this particular test, and the quick links with weak link and bungee cord are attached to one end of the bridle.

...

I'm conducting a test on a Wrap and Tie 130 pound single loop weak link attached to one end of the V-bridle... I've got a hundred pounds... one fifty... two hundred... two fifty... three hundred... three fifty... You can really see the polypro bridle stretch - unlike a Spectra bridle. Four hundred...

...

Here we're gonna do a test on one hundred thirty pound weak link, Pre-Tied, single loop, made with a Grapevine Knot and a Lark's Head. Got one hundred pounds... two hundred pounds... You can really see the polypro bridle stretch. Two fifty... three hundred...

---

HANG GLIDER UNIVERSITY
HGU
College of Higher Education
Cloud 9, Michigan

---

Test# - W&T - PT
1 - 420 - 385
2 - 380 - 380
3 - 390 - 280
4 - 390 - 360
5 - 425 - 400
6 - 400 - 375
Ave. - 400 - 363
Var. - +6/-5% - +10/-23%
SDev. - 18 - 23

Analysis:

1. These tests were conducted under controlled conditions that limit the effects of additional factors.

2. Results indicate that a "Nominal" 1g (260 lb.) Wrap and Tie weak link placed at one end of a V-bridle will break at about 400 pounds (1.54g) of tow force.

3. Results indicate that a Pre-Tied weak link has about 90% of the strength of a Wrap and Tie style weak link, with much more variance in breaking strength.

4. Results support compliance with 14CFR 91.309(a)(3)(i) for most solo gliders. (80% to 200% MCOW)

Strengths & Limitations:

1. A strength of this study is that was controlled and limited the effects of extraneous variables.

2. That strength is also a limitation, as there are many additional factors that can affect weak link strength when used for towing a hang glider.

Other factors that may reduce weak link strength:

1. Fewer wraps on a Wrap and Tie weak link.
2. Small diameter V-bridle material.
3. Spectra V-bridle material (no shock absorption).
4. Small diameter release hardware.
5. Short V-bridle.
6. Rough/poor towing technique.
7. Worn weak link.
8. More?

8. More?

Oh yes, Tracy. Where to freakin' begin...

Maybe...

http://www.hanggliding.org/viewtopic.php?t=26302
HIGHER EDUCATION ?

michael170 - 2012/06/06 03:14:26 UTC

Did anyone here bother to read Drs. Lisa Colletti and Tracy Tillman's thirteen page idiotic article in the June issue of USHPA's worthless magazine?

NMERider - 2012/06/06 03:25:09 UTC

You are being much too complimentary IMHO. I got so nauseated reading it I had to take a breather. Do you mean to tell me they wrote an article that wasn't insipid and self-congratulatory to the extreme? I've found their entire series on aerotowing to come off rather poorly to say the least. A sad waste of such exalted and highly qualified medical professionals. How do I know this? Well they won't stop patting each other on the back about how great they both are. Pardon me while I puke.

...it would've been a good idea to run some ACTUAL BENCH TESTS on the Sacred Cortland Greenspot BEFORE filling the USHPA's worthless magazine with the fourteen pages of rot you did over four and a half months prior.

But anyway...

We could get into details of lab testing weak links and bridles, but this article is already getting long. That would be a good topic for an article in the future. Besides, with our backgrounds in formal research, you and I both know that lab tests may produce results with good internal validity, but are often weak in regard to external validity--meaning lab conditions cannot completely include all the factors and variability that exists in the big, real world.

...I can't understand why you bothered doing this testing at all because you couldn't completely include all the factors and variability that exists in the big, real world. For example - there was no wind blowing on the weak links as they were approaching the point of failure.

Hang Glider aerotow weak link tests using Pre-Tied and Wrap-and-Tied single-loop130 lb IGFA green spot dacron line

It's Greenspot - one word, capitalized.

Single Loop on Polypro V-Bridle

BULLSHIT. They're single loops on a 5/16 inch steel quick links.

Here's what it says in Reference 4 - the excellent book, Towing Aloft, by Dennis Pagen and Bill Bryden - of your bullshit magazine article:

Safety Tip: The only way to insure safe, consistent weak links is to test each batch of new weak link material with the same equipment (release, rings, bridles, etc) for breaking strength.

We need to know what the weak link will do when configured as it will be IN THE AIR. So from this point on your data is pretty fuckin' useless.

260 lb "Nominal" 1G Weak Link

- Where the fuck did 260 pounds come from?

- Drop the "Nominal" crap.

- What's the significance of one G? Is that the figure that meets your idiot expectation that your weak links break as early as possible in lockout situations but are strong and reliable enough to avoid frequent breaks from turbulence?

= 260 lb. "Nominal" (not actual) 1g weak link

Let's start dealing a lot more with ACTUAL and a lot less with "NOMINAL" - asshole.

I...

- fly at 320 pounds

- don't give a rat's ass about 260 pounds, "Nominal", one G, or the several decades of experience and hundreds of thousands of tows conducted by numerous aerotow operators across the county

- use my weak link to protect my aircraft against overloading

- use a weak link which will hold through any turbulence that doesn't put me into a lockout

- have no expectation whatsoever of my weak link failing early or at any point in a lockout

- use a release I can use to abort a tow well before your "Nominal" piece of shit fishing line will let you off

- develop methods and technology that work better than the crap you shitheads are using as standard practice today

- don't wait to implement superior methods and technology until after it's been embraced by the douchebags that control this sport

I cut about twelve inches of material, wrapped it around a quick link about six times...

Oh! You wrapped it around a quick link ABOUT six times. So we don't know how many times you had ACTUALLY wrapped it around the quick link for any given test. Four... Five... Six... Seven... Eight...

...tying the ends together with three Overhand Knots, and then pulling on a center loop, pulling it tight, and isolating the knots as much as possible from the loop itself.

- Those aren't Overhand Knots. An Overhand Knot is tied in a single strand. They're Thumb Knots:



- Yeah Tracy. Tie THREE of them - just in case first one comes untied. (Ever load up a loop of Greenspot formed with a Thumb Knot then try to untie it? I mean without using a knife?)

- Isolating the knotS?!?!?! How much more isolated do the second and third ones need to be?

- Ever experiment with fewer wraps to see if isolating the knot to that extent makes any difference?

- Ever test a simple loop between two quick links to see if any of the wrapping bullshit makes any significant difference?

For testing purposes I'll use two metal five sixteenths diameter quick links, which is the same diameter as the polypro bridles we use here at Cloud 9.

Good, Tracy. Use the same DIAMETER specifications but don't worry about what happens to the diameter of your idiot polypro when it's loaded up and constricted at the connection point.

I'm using metal quick links to reduce as many variables as possible so we can really focus on the nature of the knot and the material itself when comparing a Pre-Tied versus a Wrap and Tie weak link.

Great. Let's eliminate those variables, Tracy. You've already eliminated the variable of diameter change, so let's also eliminate the variable of the interaction of the Greenspot with the surface of the material with which it's engaged.

Here's an example of a Pre-Tied weak link. It's made, again, from a hundred and thirty pound Dacron line material and a loop is produced using a Grapevine Knot...

- You're probably NOT using a Grapevine Knot. You're probably using a Fisherman's Knot - not that there's any performance difference. If you ARE using a Grapevine all you're doing is wasting material, time, and effort. (A Grapevine is just a Fisherman's formed with Double - versus Single - Overhands.)

- So what's the "THINKING" behind using three Thumb Knots to form the loop for a Wrap and Tie versus one Fisherman's Knot to form the loop for a Pre-Tied? Wild guess... Some fucking moron with a long track record and no knot tying skills record showed you how to tie a Wrap and Tie and you never questioned his competence or anything he was saying?

...and then it's attached to the quick link using a Lark's Head.

Nobody attaches a "Pre-Tied" weak link to a bridle using a Lark's Head. The morons who swallow the crap they're being fed by their idiot AT instructors use a Double Lark's Head to:

Quest Air

...position the knot so that it's hidden from the main tension in the link and excluded altogether from the equation.

and the half dozen people who know what they're doing use a Double Lark's Head 'cause it seats well and keeps the weak link reliably secured to the bridle.

And you bloody well know that. There's a photo on Page 56 of "Reference 4" of a weak link being Double Lark's Headed onto an incredibly ratty looking polypro bridle. You're using a Single Lark's Head 'cause you think that that will yield lower and less consistent blow strengths and support the rot you wrote in the magazine.

Here you can see the test configuration using the five sixteenths polypro V-bridle configured with about the same angle that's used with an actual V-bridle on a hang glider.

- Oh! Here we can see the test configuration using the five sixteenths polypro V-bridle configured with ABOUT the same angle that's used with an actual V-bridle on a hang glider.

-- ABOUT what is that angle?

-- So now we're dealing with ABOUT six wraps of the weak link and ABOUT the same angle that's used with an actual V-bridle on a hang glider - and we're putting it on a glider that weighs ABOUT 260 pounds. I'm really liking this study of yours, Tracy.

- This is totally moronic, Tracy. You test weak links by loading them directly. You can:
-- use lighter range scales/gauges and get more accurate readings
-- then use those readings to PRECISELY translate to towline tensions for ANY *ACTUAL* bridle apex angle using trigonometry

You're the first person I know of stupid enough to do a mockup of a bridle and test at towline tension.

I'm conducting a test on a Wrap and Tie 130 pound single loop weak link attached to one end of the V-bridle...

Right, Tracy. ONE end of the V-bridle. And:
- where do the USHGA and FAA regulations say the weak link is SUPPOSED to go?
- what happens to the glider's weak link protection if that ONE end of the V-bridle fails to clear the tow ring?

You can really see the polypro bridle stretch - unlike a Spectra bridle.

Yeah, Tracy. We can really see the polypro bridle stretch - unlike a Spectra bridle.

- And when the polypro bridle is stretching the apex angle - which was ABOUT the same angle that's used with an actual V-bridle on a hang glider - is becoming more acute. Way to reduce as many variables as possible, dude.

- What differences in your test results would you speculate you'd have had using a Spectra bridle?

You can really see the polypro bridle stretch.

Yeah, Tracy. We can really see the polypro bridle stretch on the Pre-Tied tests too. Good thing we've got that shock absorption in the configuration. If we used a Spectra bridle that weak link would blow at a direct load of 230 pounds instead of 231 pounds.

Test# - W&T - PT
1 - 420 - 385
2 - 380 - 380
3 - 390 - 280
4 - 390 - 360
5 - 425 - 400
6 - 400 - 375
Ave. - 400 - 363
Var. - +6/-5% - +10/-23%

I don't buy that using the SAME material from the SAME spool tied using the SAME knots and installed and seated on the quick link the SAME way that you can get a single figure as much out of kilter as 280 is on the Pre-Tied results. Nobody who's done good bench testing has gotten anything like this - and your understanding of knots, lines, weak links, rigging sucks.

I'm gonna throw out 280 and replace it with the average of the other five tests - which is 380. (This will help and hurt some points I'm gonna make later.)

So now our averages are 401 and 380. Wrap and Tie is five and a half percent over Pre-Tied (with a Single Lark's Head on steel). Big fuckin' deal. Five and a half percent more out of a particular piece of fishing line is not worth the hassle of wrapping and tying. If I wanna beef up my weak link I'll use a heavier flavor of fishing line.

So for Wrap and Tie we've got a maximum variation from the average of 5.9 plus and 5.2 minus percent.

And for Pre-Tie we've got a maximum variation from the average of 5.2 percent plus or minus - which is very slightly BETTER than Wrap and Tie gets.

Note that the low test for Wrap and Tie is twenty pounds UNDER the high test for Pre-Tie.

Tracy Tillman - 2012/06

IGFA braided Dacron fishing line is readily available in a wide range of strengths that work for us, including 100, 130, 160, 180, 200, 250, and 300 lb. line. One source states that their Dacron braided line is IGFA approved, and they publish a chart of the actual tested breaking strengths for their various lines [ref 13]. They state that their 130 lb. line breaks within one pound of 130, which is 5 to 10 times more precise than a metal TOST weak link. Their least precise 180 lb. line breaks within four pounds of 180 lbs., which is still twice as precise as a metal TOST weak link.

Super, Tracy. We've got this ultra precise fishing line that's good to better than plus or minus 0.8 percent but under your controlled bench testing conditions the best you can do is well over five percent either way.

These tests were conducted under controlled conditions that limit the effects of additional factors.

Those tests are rot. You can't install weak links on 5/16 inch steel quick links and pretend that your figures tell you anything about what happens on bridles.

And - here's a thought...

- Maybe you DID test the Greenspot installed on bridle material and got the same 130 pound average everybody else does.

- So to save face after publishing that idiot article with the claim of 260 pounds you found out you could up the blow point to 230 by installing it on fat smooth quick links.

Results indicate that a "Nominal" 1g (260 lb.) Wrap and Tie weak link placed at one end of a V-bridle will break at about 400 pounds (1.54g) of tow force.

Yeah, I think I'm on to something here.

- If you had published tests for direct loading using the quick links your highest Wrap and Tie test - assuming a sixty degree bridle apex angle - would be 244 pounds. And your lowest would be 218.

- Given that you don't specify an apex angle and that your target audience is too fuckin' stupid to be able to do the math anyway - this way you don't have to admit that your claim in the magazine was bullshit.

Results indicate that a Pre-Tied weak link has about 90% of the strength of a Wrap and Tie style weak link, with much more variance in breaking strength.

- And most of the "superiority" of Wrap and Tie is owed to ONE aberrant - and highly suspicious - Pre-Tied data point.

- Your EXPECTATION of your weak link is that it break as early as possible in lockout situations but is strong and reliable enough to avoid frequent breaks from turbulence. So wouldn't a Pre-Tied weak link that blew at 280 pounds in a lockout situation and held to 400 in turbulence be far superior to the Wrap and Tie with its much more limited range of options?

Results support compliance with 14CFR 91.309(a)(3)(i) for most solo gliders.

Which was the whole purpose of your rigged testing. You want to be able to provide documentation to the fuckin' FAA and/or Tim Herr when somebody gets killed as a consequence of an illegal understrength weak link that these crappy little pieces of fishing line - that you and your douchebag buddies have been forcing everyone to use and crashing them with for a couple dozen years - put all solo gliders safely above the legal minimum.

If you were the least bit interested in keeping the pilots safe you'd do what is done in sailplaning - use manufacturer specified weak links for individual glider models that put everybody at around 1.4 times Maximum Certificated Operating Weight. But all you wanna do is try to keep your Flight Park Mafia and USHGA asses covered.

(80% to 200% MCOW)

Yeah, motherfucker?

- The LOWEST figure you got for a Pre-Tied loop of 130 pound Greenspot was 280 pounds towline tension.

THIS:

http://vimeo.com/17472550

password - red
2-1306
http://farm8.staticflickr.com/7258/13851486814_77efdf1004_o.png


is a virgin Pre-Tied loop of 130 pound Greenspot. You tell me that it held to 280 pounds towline - about two and a quarter times normal 914 Dragonfly tension - and blew due to Spectra shock.

- You're saying that a Wrap and Tied loop of 130 pound Greenspot on the top end of a two point bridle can deliver as much as 425 pounds of towline tension.

-- On a one point bridle that would translate to about 488 pounds towline.

-- And if you use Wrapped and Tied Greenspot on BOTH ends of a one point bridle at Quest or Florida Ridge you're up to 976.

-- So what's the capacity of a Dragonfly tow mast breakaway and what are the implications with respect to the FAA regulation requiring that the front end weak link exceed what's on the back end?

- Did you test a three strand weak link...

Lisa Colletti - 2012/06

What about a three-line weak link?

Tracy Tillman - 2012/06

It is an acceptable method, but not necessarily a de facto standard. It can be used to make, for example, a 390 lb. weak link from 130 lb. line for use on a tug. It requires the use of two knots, one at each end of the weak link to attach it to the bridle or ring, and it doesn't really work on a pilot V-bridle.

...to confirm that, in that case, exposed knots don't affect the strength of the line and you get the full 390?

A strength of this study is that was controlled and limited the effects of extraneous variables.

This "study" had no strengths. It's purpose was to legitimize shoddy, dangerous, illegal industry practices.

That strength...

What strength?

...is also a limitation, as there are many additional factors that can affect weak link strength when used for towing a hang glider.

Like reality - a factor you very deliberately eliminated.

Other factors that may reduce weak link strength:

I see you're not too worried about factors that may INCREASE weak link strength and push the TOP end of the legal range.

1. Fewer wraps on a Wrap and Tie weak link.

- So why didn't you run any tests with:
-- fewer wraps and get an answer?
-- Pre-Tied weak links installed with a Double Lark's Head?

- I notice you didn't report anything about the points on any of the weak link configurations at which the material failed.

2. Small diameter V-bridle material.

- Fuck you. You didn't do ANY testing on ANY bridle material of ANY diameter.

- Right. So if anybody uses anything under your 5/16 polypro it's HIS fault when a loop of 130 pound Greenspot blows.

3. Spectra V-bridle material (no shock absorption).

OK, Spectra people. Somebody write in and tell me when the last time he felt a shock on any kind of tow.

4. Small diameter release hardware.

So how come you didn't run a test using a parachute pin based barrel release and report that the weak link failed at the pin and at an abnormally low tension?

5. Short V-bridle.

Fuck you.
- You didn't report an apex angle for your tests.
- NOBODY tows with two point bridles short enough to make a significant difference.

6. Rough/poor towing technique.

Fuck you.

- Yeah, they probably need some tandem Cone of Safety training at Cloud 9.

- Weak links aren't supposed to blow due to rough/poor towing technique. What's rough/poor towing technique in one situation will be necessary to stay alive technique in another.

- Weak links are ONLY supposed to blow to keep the glider from being overloaded and if they blow in anything short of a full blown and severe lockout they weren't up to the job.

7. Worn weak link.

- Maybe if hang gliding would ever get its stupid shit together enough to get hardware designed to do the job in the air instead of using spinnaker shackles we wouldn't wear weak links.

- Anybody who goes up with a worn weak link should have his fuckin' rating suspended.

8. More?

- Prediction...

We could get into details of lab testing weak links and bridles, but this article is already getting long.

This crap is gonna serve as the foundation of the next in the series of "Higher Education" magazine articles.

- Kudos to Steve for unearthing this smoking gun.

[Zack C]

- Maybe you DID test the Greenspot installed on bridle material and got the same 130 pound average everybody else does.

- So to save face after publishing that idiot article with the claim of 260 pounds you found out you could up the blow point to 230 by installing it on fat smooth quick links.

Tad, can you run a test with a Greenspot loop installed on a quick link for comparison? I doubt we'll see Tracy repeat the test with the weak link installed directly on the bridle.

Zack