Weak links

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=32824
Weaklink testing

Davis Straub - 2013/07/04 13:47:57 UTC

Weak Link loops breaking test - April 2013
All knots tied with single fisherman's unless specified.

Breaking Lbs - Material

463 - Spectra Line used for Aero-towing (taken from used tow line, NOT NEW)

000 - (http://www.towmeup.com/weaklink.html)

330 - White with Black striker 300 lb.
308 - White with Red Striker 250 lb.
253 - White with Purple Striker 200lb 1knot
255 - White with Purple Striker 200lb 2knots

220 - Black Dacron fishing line 160 lb.
330 - Actual Tug Weaklink (Doubled Black) Black Dacron fishing line 160 lb.
286 - 205 Leach Line
154 - Courtland Greenspot 130 lb. (From Quest Air Florida)
099 - Cabellas Greenspot 130 lb.

187 - Double Loop Cabellas Greenspot
077 - Cabela's Greenspot No Lark's head
198 - Tandem Knot Cabela's Greenspot

Cabela's Green spot did not give consistent results) Not recommended

So what's the deal here Mark and Jim?

- Did you do, like, five tests apiece for each of the twelve flavors and get EXACTLY the same number every time? 72 tests and there was never a pound's worth of variation from one to the next in any of the dozen runs?

When Billo tested ten repetitions of 130 pound Greenspot...

http://ozreport.com/forum/viewtopic.php?t=12512

...he scribbled the results on a piece of paper, took a photo...



...with the top figure cut off entirely and the ninth partially obscured by the testing wreckage and we have:

117 - 134 - 130 - 139 - 137 - 134 - 112 - 119 - 121

(And then idiot fucking Gerry treated Billo's kilograms as pounds and converted them to kilograms to produce some clever little tables and graphs based on figures less than half of the actual values.

And none of the Davis Show fucking geniuses saw anything wrong with a standard aerotow weak link that blew at an average of 57.7 pounds.

But if you average that with the 260 pounds everybody assumes he's getting when he does a good job of hiding the knot you get 159 pounds which is only 25 percent over the 127 pound average that Billo ACTUALLY got for the figures we can actually SEE.)

Billo got an average of 127 with a low 15 pounds off and a high 12 pounds off (and still 15 pounds under your figure).

But you got EXACTLY 154 pounds for five successive tests.

- Or did you just to one test apiece and assume that others would be identical?

- But if you just did one test apiece how did you determine that the Cabela's crap blew too "inconsistently" to meet with your high aeronautical standards and everything else had the precision that's always been so critical for the safety of hang gliding aerotow operations?

- Or did you do multiple tests on all flavors, pick out the number that you liked best, and throw out all the data that you didn't like.

I think the answer here is pretty fuckin' obvious.

(Maybe somebody on speaking terms with OP can persuade him to come to our rescue with his 10 kiloNewton tensile tester, scanning electron microscope, and keen understanding of "the difference between acceleration, mass, and what a forces are".)

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=32824
Weaklink testing

154 - Courtland Greenspot 130 lb. (From Quest Air Florida)
099 - Cabellas Greenspot 130 lb.

187 - Double Loop Cabellas Greenspot
077 - Cabela's Greenspot No Lark's head
198 - Tandem Knot Cabela's Greenspot

Cabela's Green spot did not give consistent results) Not recommended

"Inconsistent" is USHGA / Flight Park Mafia doublespeak for "light". In that crap he smeared all over the magazine thirteen months ago Trisa refers to "(in)consistence" in weak links ten times to talk about them causing "inconvenience" versus getting the glider to altitude.

Similarly, but more transparently, while "safer" weak links are...

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Jim Rooney - 2013/03/05 21:40:02 UTC

You're afraid of breaking off with a high AOA? Good... tow with a WEAKER weaklink... you won't be able to achieve a high AOA. Problem solved.

...lighter weak links - which on one, including 165 pound Falcon 3 145s and the assholes advocating, them ever actually uses - "better" weak links are ALWAYS...

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Zack C - 2013/02/22 00:58:05 UTC

By 'better' I'm going to assume you mean 'stronger', as no one is promoting weaker weak links.

...*STRONGER* weak links. And preferably they're...

Dr. Trisa Tilletti - 2012/06
HIGHER EDUCATION

TIE A (BETTER) WEAK LINK

...twice as good/consistent as a loop which blows at 130 pounds.

THIS:

Cabela's Green spot did not give consistent results) Not recommended

is BULLSHIT. A brand or lot of string that comes out of the back end of any factory may be stronger or lighter than what it says on the spool's label but samples taken from any points on the spool are gonna blow just as CONSISTENTLY as samples taken from any points on a spool of the sacred 130 pound Cortland Greenspot that's served us all so remarkably well over the course of the past couple of decades.

Mark, Jim, Davis, Quest, Trisa, USHGA can't afford to tell people that the Cabela's line is not recommended because it's dangerously LIGHT because there's no such thing as dangerously light - that's an oxymoron. If there were such a thing as dangerously light that would contradict everything The Industry has been shoving down our throats for the past thirty years and open up the possibility that Zack Marzec was killed by a dangerously light weak link rather than an invisible dust devil.

So if you run ten tests on loops from a spool of 130 from Cabela's and everything blows within a pound of 100 that's just too INCONSISTENT to be safe. A 99 pounder might break unexpectedly for no reason and crash you and a 101 pounder might not break when it's supposed to and you could die in a low level lockout - and probably take the tug with you. And that's a state of affairs that hang glider towing simply can't tolerate. Use it if you want - and your tug driver permits you - but don't blame us if you get a broken arm from a stall or broken neck from a lockout.

Also...

People who test 130 pound Greenspot weak links ALL agree that it blows at around 130 pounds, plus or minus about ten percent. The Reason Mark Knight and Jim Keen-Intellect Rooney - and the commercial interests which made this testing and results publication happen - got 154 pounds / 18 percent over what everybody else gets is that they need this crap to be as high as possible to get Zack Marzec, and all the other victims of the Rooney Link's Reign of Terror - into or higher into the FAA legal range.

No, Zack was flying at 1.2 Gs - 0.4 Gs up into the legal range. No real problem there. Sometimes shit just happens.

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=12512
Weak Links

George Stebbins - 2008/07/13 21:01:44 UTC

(I'm not that knowledgeable about weak links, I mostly just trust Quest on this...

http://4.bp.blogspot.com/-bRrpHNa68iY/UQ6Pv9gRZyI/AAAAAAAAjTg/Hc22bx5122Q/s2048/20943781_BG1.jpg

...and use their links when possible, and Hungary Joe's when not. I think his are the same as theirs.)

Whatchya gonna do now, George? Quest doesn't even trust Quest anymore and they won't tell anybody what their weak links are.

Fuckin' Idiot.

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=32824
Weaklink testing

Mark Knight - 2013/07/04

We tried to simulate how the rope is pulled while on aerotow.

My experience in weak links breaking during lock out is that it does not happen very fast. The line is pulling and pulling and pulling and then it snaps. It takes about two or three seconds. I have induced a lockout purposely and not on purpose several times with the tandem glider and students above me in the harness. It may seem like it's very fast but if you analyze the whole thing from start to finish it takes a few seconds.

So with the come-a-long I would put the tension on the loop over about a two to four seconds before it would break. The weak link material really stretches a lot before it breaks. If you stop the test before it breaks, you will see your loop has now stretched and will be longer than it was originally. If you then do the test again it will break much sooner than the rated breaking strengths. What this would suggest to me is, if you have a close to lockout or old link that has been stretched many times, replace it with a new one.

We tried to simulate how the rope is pulled while on aerotow.

Wouldn't you have to actually know how the rope is pulled while on aerotow before TRYING to SIMULATE it?

Do any of you dumb motherfuckers even have the slightest clue what normal 914 Dragonfly aerotow tensions are?

Hell, even after over five weeks subsequent to Zack Marzec's freak accident and being told repeatedly by a weekend warrior Jim Keen-Intellect Rooney has deemed too ill suited to aerotowing...

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Jim Rooney - 2013/02/17 10:37:47 UTC

I'm not sure who you're arguing with Zack, but it's sure not me... cuz man... you've got some pretty big hangups mate.

You're hear to argue. Plain and simple. I've got better stuff to do.
Go blow smoke somewhere else. I couldn't give a rats ass... I won't be towing you so what do I care?

...to hook up behind him is...

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Jim Rooney - 2013/03/11 20:57:51 UTC

Sorry, yes it's early... Just under... As you've said many times... 130 breaks at100 right?

...he's still thirty pounds under what a Rooney Link actually blows at.

Zack C - 2013/03/11 21:11:28 UTC

I suspect you're trolling, but if not, I've said many times that
- 2 strands of 130 breaks at 130
- 2 strands of 200 breaks at 200
- 4 strands of 130 breaks at 200

He's 23 percent low and 54 pounds / 35 percent under what you reported from your alleged testing. And a 100 pound weak link on a two point bridle translates to 174 pounds towline. So Jim Keen-Intellect Rooney thinks he's been towing 350 pound Glen at Ridgely at just under half a G and 0.3 Gs south of legal - even assuming Glen's maxing out his glider.

Did you simulate the stress the weak link feels during dolly acceleration? That's where my experiments showed the tension on a typical tow to be highest by far. I got about 160 to 175 on acceleration versus 125 in the air.

My experience in weak links breaking during lock out is that it does not happen very fast.

Yeah...

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

Jim Rooney - 2011/08/28 19:39:17 UTC

One of the biggest bits that seems to be under appreciated is the bit that weaklinks break under shock loading.
They can take a hell of a lot more force if they're loaded slowly... which is exactly what happens in a lockout.

Most people don't experience this first hand.
It's because most pilots will hit the release before the weak link breaks... as they should. Most pilots understand this concept. I'd say almost all do.

Now, it happens fast.
Many pilots still get off line quick as well.
So most have not seen just how much force it takes to break a smoothly loaded weaklink. It's way more than you'd imagine.

What most have experienced is a weaklink that breaks due to shock loading.
This is very different.
They break so exceptionally easier under shock loading.
Even that initial pull on the cart is a severe shock load when compared to a lockout. Even when it's a "smooth" start.

(Which you know, motherfucker, as a consequence of the equipment I developed and the tests I ran at Ridgely.)

The trouble is, this is what pilots are familiar with.
So it's natural to start thinking about what a weaklink "should" be in relation to shock loading and missing the reality of a smoothly loaded weaklink and the sheer speed of a lockout. As I pointed out before, they are exponential in nature... you hit a "tipping point" and then all hell breaks loose.

Most people get this.
So I'm sorry for boring you with what you know already.
It just needs to be pointed out from time to time, especially when the old misconceptions start rearing their heads or when you've got people new to all this showing up.

So did you run simulations to determine why a Rooney Link holds so long and well in a lockout but...

http://vimeo.com/17472550

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


...vaporizes for no reason during normal climbing and maneuvering in normal conditions?

How come you didn't...

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

Jim Rooney - 2012/05/28 11:49:58 UTC

Think about it... you're going a million miles an hour under huge (relatively speaking) line tension as you come blazing out of the cart struggling to "stay down"... as you slam into turbulent air. Hell yes you're going to break weaklinks. That's what they're there for!
You're subjecting them to massive loadings.
(The shock loading a weaklink sees as you hit the propwash is far greater than people appreciate)

...run shock load tests so Jim Keen-Intellect Rooney could tell everybody that a weak link that blows at 154 pounds when the tension is ramped up over a period of two to four seconds blows at 93 pounds when shock loaded the way it is when a glider slams into 914 propwash at Mach 5?

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Jim Rooney - 2013/02/16 23:18:54 UTC

Naw... You want me to make bold black and white statements so that you can have a go.
Unfortunately that's not what you're getting.
Some people listen with the intent of understanding.

Others do so with the intent of responding.

I guess the fewer actual numbers you put out the fewer things you're gonna have blowing up in your faces when people start calling you to account for all the crap you've been spewing out before.

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=32857
Weaklink testing from Cloud 9

Davis Straub - 2013/07/05 11:16:01 UTC

Tracy and Lisa

Trisa.

Cloud 9, Iosco, Michigan

Check out this thoroughly documented test of 130 pound Greenspot:

Yeah, THOROUGHLY documented - expect for the facts that he's:
- installing the weak links on 3/13 inch quick links instead of bridle material
- not documenting the bridle apex angle
- using polypro so the bridle apex angle constantly decreases with tension so there's a constant factor of decreased load on the weak link
- doing the testing in a hangar where he can't completely include all the factors and variability that exist on tow like:
-- sunshine
-- airspeed
-- altitude
-- pitch attitude
-- insect strikes
-- shock loading
-- the comfort levels of the pilots
-- what the flight park decided they were happy with
-- the weak link pop management skills of the glider pilot
-- the position of the glider relative to the Cone of Safety
-- the coefficient of friction of the surface on which the glider's being dragged
-- whether:
--- the tug driver has been informed of weak link strength
--- a tension increase is due to a lockout or turbulence
--- the glider is right side up or upside down
--- the bridle is:
---- polypro which acts as a shock absorber
---- Spectra which acts somewhat like an impact wrench
--- the glider pilot is:
---- someone who's been at an around all this plenty long enough to understand what's what and who's who like Davis
---- a muppet like Zack C

- If this test is so fucking thoroughly documented how come it has numbers all over the place with averages, variations, and standard deviations instead of precise figures like Mark Knight and Jim Rooney got?

- How come none of the figures for Wrapped and Tied weak links are particularly close to the 452 pounds we'd expect to get for a two point bridle with the 260 pounds Trisa assured us we'd get in his 2012/06 Higher Education magazine article?

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

Mark Dowsett - 2013/07/09 10:19:16 UTC

One question to the weak-link formula I have is... does anyone know the actual tow force on the tow rope during an aero-tow? With winches, we have an accurate idea of course but I haven't met anyone that knows the answer to my question. Not easy to measure.

Why don't you ask Jim Keen-Intellect Rooney or the pigfuckers at Quest who've been perfecting aerotowing for twenty years and having incredibly deep discussions on aerotowing that we muppets couldn't possibly follow?

And until we know what the tow-line pressures are, how are we to KNOW what weak-link to use...?

If you had a fuckin' clue what you were talking about you would:
- not be referring to towline PRESSURES
- understand that normal tow tension has ABSOLUTELY NOTHING to do with what weak link to use
- have read the figures I managed to obtain - while Ridgely was doing its best to fuck me over

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=32857
Weaklink testing from Cloud 9

JD Guillemette - 2013/07/09 17:31:52 UTC

I thought weak link strength was determined by the mass (weight) of the system being towed regardless of the tow line tension.

Well, you're way ahead of Pagen and Bryden but still far short of understanding what a weak link is.

So weak link strength should a function of the combined weight of Glider and Pilot.

If you're trying to use it as a lockout protector - which you and the stupid pigfuckers at Ridgely who signed you off and taught Jim Keen-Intellect Rooney everything he knows are.

What that function or relationship is has been discussed before on this forum with many different opinions.

Hundreds of them. But the people who understand what a weak link is and refuse to offer anything remotely resembling an opinion tend the get threatened and silenced and excluded from that forum. And you're never gonna be bright enough to get it anyway.

Jim Gaar - 2013/07/09 19:21:52 UTC

Risk management?

I too struggle with this kind of testing.

The only things you've ever struggled with in your entire life are trying to pass yourself off as someone with actual substance and attempts at damage control when you get found out.

The whole tow, damn near ANY tow is dynamic...

Three whole syllables.

...and fluid. Just putting constant pressure...

From all that dynamic fluid.

...on a weaklink until it brakes...

Brake fluid - to be specific.

...seems too inconclusive,

What a load of pseudo-intellectual Rooney following crap.

BUT thanks to Cloud 9 for giving as good a go as one could on the ground.

Yeah, top notch. The only weak link testing I've ever seen that produces results from which it's impossible to determine the breaking point of a single sample - and would've been ever if the mounting HAD been on a bridle instead of a Quick link. Hard NOT to for a couple of sleazebags to get a compliment from a fellow sleazebag for devising a test and publishing results intended to mislead, obscure the truth, cover asses, and further dumb the sport down.

And let's not forget to thank Cloud 9 for all their participation and expert leadership in the Zack Marzec discussions and for ensuring that never again would someone die as a consequence of violating USHGA aerotowing regulations, standards, guidelines, recommendations, or suggestions.

P.S. Note all the answers in response to Mark Dowsett's question regarding aerotow tension that have poured in during the 22.75 hour period since he posted it. Notable luminaries not responding...
- Jim Keen-Intellect Rooney
- Bobby Fucking-Genius Bailey
- Mark Prefer-Not-To-Engage-In-Speculation-At-This-Point Frutiger
- Paul Invisible-Dust-Devil Tjaden
- Lauren Eminently-Qualified-Tandem-Pilot Tjaden
- Dr. Trisa Higher-Education Tilletti
- Russell Go-Ahead-And-Double-Them Brown
- Mark You-Have-No-Idea-What-Happened Knight
- Bart No-Stress-Because-I-Was-High Weghorst
- Steve Exceptionally-Knowledgeable Wendt
- Jim Your-Mileage-May-Vary Gaar
- Davis I've-Never-Had-A-Problem Straub
- Matt Not-Warranted-As-Suitable-For-Towing-Anything Taber
- Dennis Excellent-Book Pagen

[Tad Eareckson]

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Zack C - 2013/02/17 13:33:05 UTC

From the rules for the last Big Spring comp:

Pilots must use weaklinks provided by the meet organizers and in a manner approved by the meet organizers. All weaklinks will be checked and use of inappropriate weaklinks will require the pilot to go to the end of the launch line to change the weaklink.

Weaklinks will consist of a single loop of Cortland 130 lb Greenspot braided Dacron Tolling line and should be placed at one end of a shoulder bridle.

Zack C - 2013/02/19 05:35:59 UTC

Davis Straub - 2013/02/19 03:13:45 UTC

Yup. The orange string used for tandems at Wallaby. Has been for years. I use it also. 200 lbs.

Any chance this stuff will be allowed at Big Spring this year?

And, of course, we get no response whatsoever 'cause trying to get a straight answer from a worm like Davis is a lot like trying to get wool from a carp.

But today if we go to:

http://ozreport.com/2013USNationalsrules.php
2013 US Nationals at Big Spring, Texas

we find that the:

Weaklinks will consist of a single loop of Cortland 130 lb Greenspot braided Dacron Tolling line

clause - which was present at the time Zack (the still alive one) asked - has mysteriously disappeared.

What we NOW have is:

2.0 EQUIPMENT

Weaklinks

Pilots must use weaklinks provided by the meet organizers and in a manner approved by the meet organizers. All weaklinks will be checked and use of inappropriate weaklinks will require the pilot to go to the end of the launch line to change the weaklink.

Weaklinks should be placed at one end of a shoulder bridle. The tow forces on the weaklink will be roughly divided in half by this placement. Pilots will be shown how to tie the weaklink so that it more likely breaks at its rating breaking strength.

So questions arise...

- Are these meet organizers the same pigfuckers who've been forcing everyone up on Davis Links at all US and Australian competitions ever since Robin Strid's stronglink (and Bobby's standard weak link) failed to prevent him to get into a low level lockout when his Quallaby (Bobby Bailey designed) piece of shit "release" snagged the focal point of his safe towing system?

- How does volunteering to organize a pecker measuring contest qualify someone to dictate weak link standards to competition pilots?

- Who are the meet organizers?

- What do the meet organizers use for weak links (if any) for themselves?

- Are the meet organizers:

-- totally cool with the crap Trisa wrote in his weak link article in the 2012/06 issue of Hang Gliding? I'm guessing they are 'cause I didn't read any letters to the editor condemning it.

-- on board with Paul Tjaden's report that Zack Marzec's standard aerotow weak link and pro toad bridle had nothing to do with his fatal 2012/02/02 whipstall and tumble and that the freak accident was probably a consequence of an invisible dust devil?

- Did the meet organizers participate in the Zack Marzec postmortem discussions and help set all of us comp pilots and muppets straight on this hang glider weak link issue? Why not?

- If the meet organizers do something other than dictate Marzec Links for all gliders doesn't that clearly indicate that meet organizers of all pre Marzec competitions - mostly or entirely themselves - didn't know what the fuck they were doing?

- Would the meet organizers approve of having weak links installed:

-- in compliance with FAR 91.309(a)(3) which specifies that the weak link be installed at the end of the TOWLINE?

-- on BOTH ends of the bridle, despite the fact that this...

http://www.hanggliding.org/viewtopic.php?t=27393
Pro towing: 1 barrel release + weak link or 2 barrel release

Juan Saa - 2012/10/18 01:19:49 UTC

The normal braking force in pounds for a weak link is around 180, at least that is the regular weak link line used at most aerotow operations. By adding a second weak link to your bridal you are cutting the load on each link by half, meaning that the weak link will not break at the intended 180 pounds but it will need about 360.
I made the same mistake on putting two weak links thinking that I was adding protection to my setup and I was corrected by two instructors on separate occacions at Quest Air and at the Florida RIdge.

...is known to double the towline tension limit?

- Will any competitors be granted permission to fly two point bridles?

- If any competitors are granted permission to fly two point bridles will they also be granted permission to use fifteen percent heavier weak links to bring them up to the same towline tension capacity as the pro toads?

- What percentage of competing gliders do the meet organizers anticipate...

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.

...forcing off the bottom end of the legal range this time?

- If the meet organizers find that after all their carefully calculated weak link standards are implemented they can't get any gliders in the air - probably just due to coincidence - are they going to follow the Russell Brown Precedent and tell everybody to just double what they've got?

- Is the deletion of the "Weaklinks will consist of a single loop of Cortland 130 lb Greenspot braided Dacron Tolling line" clause for the first time since the Zack Marzec fatality a response to the Zack Marzec fatality or just another coincidence?

- What, in the collective opinion of the meet organizers, are the three most important purposes of the weak link? I can only assume that they're in accordance with Davis's position that...

http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks

Davis Straub - 2013/03/06 18:29:05 UTC

You know, after all this discussion I'm now convinced that it is a very good idea to treat the weaklink as a release, that that is exactly what we do when we have a weaklink on one side of a pro tow bridle. That that is exactly what has happened to me in a number of situations and that the whole business about a weaklink only for the glider not breaking isn't really the case nor a good idea for hang gliding.

I'm happy to have a relatively weak weaklink, and have never had a serious problem with the Greenspot 130, just an inconvenience now and then.

-- it's a very good idea to treat the weaklink as a release, that that is exactly what we do when we have a weaklink on one side of a pro tow bridle

-- the whole business about a weak link only for the glider not breaking isn't really the case nor a good idea for hang gliding

-- you can never have a serious problem with the Greenspot 130, just an inconvenience now and then

- Will the organizers provide heavier weak links to competitors who've...

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Jim Rooney - 2013/02/15 06:48:18 UTC

Davis has been at an around all this plenty long enough to understand what's what and who's who.

...been at an around all this plenty long enough to understand what's what and who's who or will weak link strength be proportional to flying weight or glider capacity?

- Why aren't we being told what weak links will be provided and required by the meet organizers?

-- Have they not yet determined what weak links will provide the most effective lockout and stall protection for the competitors?

-- Are they scared shitless of committing to one or two flavors of fishing line because...

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Jim Rooney - 2013/02/16 23:18:54 UTC

Naw... You want me to make bold black and white statements so that you can have a go.

...the nanosecond they use something involving an actual number they'll get their balls cut off and shoved down their throats by one or more of the half dozen people who understand this issue and know what's going on?

- The weak link, as we all very well know, is the focal point of any safe towing system because it saves gliders from getting too far out of whack and into too much trouble. So why is it that - with just over eighteen days to go prior to the start of the 2013 US Nationals competition - the pilots who's lives will be primarily dependent upon the degree to which these weak links will meet their expectations of breaking as early as possible in lockout situations but not inconveniencing them very much by breaking unnecessarily in the turbulence they've traveled so far to capitalize on are being deliberately kept totally in the dark as to what they'll be dealing with?

- How come the meet organizers aren't dictating the parachute model, size, and mounting they'll permit?

- Is this the way critical safety equipment issues are handled in other sports? In Formula One racing do they withhold information about the restraint and fire suppression systems they'll be allowed to use until the night before they hit the course?

What a load o' crap. Stay tuned...

[Tad Eareckson]

http://ozreport.com/2013USNationalsrules.php
2013 US Nationals at Big Spring, Texas

- Will the mystery weak links be lighter...

http://www.chgpa.org/forums/viewtopic.php?f=2&t=3600
Weak link question

Jim Rooney - 2008/11/25 19:21:57 UTC

Why lower numbers? Because your choice is lower or higher... and higher is more dangerous than lower.

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Jim Rooney - 2013/03/05 21:40:02 UTC

You want MORE.
I want you to have less.
This is the fundamental disagreement.
You're afraid of breaking off with a high AOA? Good... tow with a WEAKER weaklink... you won't be able to achieve a high AOA. Problem solved.

...than the previous standard? Seems only logical since going higher is more dangerous and lower only results in inconvenience.

If you're going:

- lower:

-- how come the weak link testing that Mark Knight and Jim Keen-Intellect Rooney did and Davis published...

http://ozreport.com/forum/viewtopic.php?t=32824
Weaklink testing

...was all on 130, which you've always specified and mandated before, and higher, from 160 to 300?

-- why do you need to show us...

Pilots will be shown how to tie the weaklink so that it more likely breaks at its rating breaking strength.

...how to tie the weak link so that it more likely breaks at its rating breaking strength? We all know that if we don't hide the knot from the main tension in the link as well we can get the weak link to blow at a much safer rating.

[Tad Eareckson]

http://ozreport.com/2013USNationalsrules.php
2013 US Nationals at Big Spring, Texas

Pilots will be shown how to tie the weaklink so that it more likely breaks at its rating breaking strength.

- What IS its rated breaking strength?

http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks

Davis Straub - 2013/03/06 18:29:05 UTC

I'm thinking about doing a bit more testing as there seemed to be some disagreement around here about what the average breaking strength of a loop of Greenspot (or orange) weaklink was.

It's been a bit over two decades since everyone and his dog started being forced up on the ideal 130 pound Greenspot standard aerotow weak link and nobody yet seems to be able to determine its rated breaking strength - 100, 120, 130, 154, 180, 200, 260, 360. Think we'll be able to pin another flavor of fishing line down sometime in the next decade if we go all out and get two or three times as many people offering their opinions on it?

- How is it humanly possible to determine a rated breaking strength?

Dr. Trisa Tilletti - 2012/16

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.

-- If you test it in the lab to determine its rated breaking strength you can't completely include all the factors and variability that exist in the big, real world.

-- And if you send it up so that it's exposed to all the factors and variability that exist in the big, real world you can't determine its rated breaking strength.

It's like some unholy hybridization of Catch-22 and the Heisenberg Uncertainty Principle.

- Define "MORE LIKELY".

- If we:

-- tie a weak link such that it breaks precisely at what someone states/pretends is its rated breaking strength what does that do for us?

-- are:

--- in a lockout or being dragged with inaccessible Davis Mini Barrels wouldn't we want the weak link to break at a lot less than its rated breaking strength?

--- trying to fly through turbulence to go on task instead of getting back in line for a relight or standing on our tails in monster thermals with the bar stuffed trying not to be inconvenienced by whipstalls into invisible dust devils and freak accidents don't we want the weak link to break at a lot more than its rated breaking strength?

- Don't lighter and heavier gliders flying the same weak link want it to break at less and more than its rated breaking strength respectively to better meet their expectations of breaking as early as possible in lockout situations but being strong and reliable enough to avoid frequent breaks from turbulence?

- Does the bridle material and/or diameter have any effect on breaking strength or...



...can we just tie it onto whatever we feel like?

- How many tows can we get on it and still have it more likely to break at its rated breaking strength?

- If:

-- it weakens through use cycles and becomes more likely to break at less than its rated breaking strength does it become an inappropriate weak link or is "inappropriate" a synonym for anything over fresh 130?

-- there's such a thing as an inappropriately weak weak link how are you going to be able to identify one that's had more than ten cycles and send the violator to the end of the launch line to change it for a fresh one?

-- someone wanted to fly an inappropriately weak weak link:

--- wouldn't it be fairly easy for him to avoid detection by...

http://ozreport.com/forum/viewtopic.php?t=32824
Weaklink testing

Mark Knight - 2013/07/04

The weak link material really stretches a lot before it breaks. If you stop the test before it breaks, you will see your loop has now stretched and will be longer than it was originally. If you then do the test again it will break much sooner than the rated breaking strengths.

...loading it up to eighty percent of its breaking strength before hooking up?

--- couldn't he just tie it in some manner such that it's less likely to break at its rating breaking strength - or do you insist on it being tied such that it's more likely break at its rating breaking strength?

[Tad Eareckson]

http://ozreport.com/2013USNationalsrules.php
2013 US Nationals at Big Spring, Texas

Pilots will be shown how to tie the weaklink so that it more likely breaks at its rating breaking strength.

Oops. I've been misreading Davis's obfuscatory crap a little - not that it really matters any. I've been reading and thinking "rating breaking strength" as "rated breaking strength".

By "rating breaking strength" he's undoubtedly relating the weak link strength to the test strength of whatever fishing line some flight park's decided it's happy with.

- The people who are trying to rescue hang gliding from Industry shits like Davis, Rooney, Paul, Lauren, and Trisa and want to put out accurate numbers find that a loop of fishing line secured to an end of a typical bridle blows at about the test strength of the line being used - two strands doubles it but the knot, no matter what it is...

Mark Knight - 2013/07/04

The knots do not matter so much for just one tow to how they break or the breaking strengths. A double fisherman's knot or a Tandem multi-wrap knot will not give better strength but wears less on the weak link and therefore last longer.

...or how it's configured, cut things back in half.

The loss is because the fibers on the inside of a turn are feel less tension / aren't pulling their share of the load while those on the outside feel more / are pulling more than their share.

And even if you COULD "take the knot out of the equation" a loop - by definition - isn't straight and you still have in and out side fibers being differentially loaded.

- But by "rating breaking strength" the Industry shits mean:
-- single loop of 130, 2 strands - 260
-- double loop of 130, 4 strands - 520

And we're supposed to just assume these values because...

Dr. Trisa Tilletti - 2012/16

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.

...and we now really need the numbers as high as possible to show the FAA that we're in compliance with aerotowing regulations and shield ourselves from liability after we kill a Zack Marzec with a Davis Link.

So...

Pilots will be shown how to tie the weaklink so that it more likely breaks at its rating breaking strength.

...we're still gonna be going up on 130 pound Greenspot but by using the Trisa Wrap and Tie method we're gonna be hiding the knot a lot better than the Quest Fisherman's Knot and Double Lark's Head so it's more likely to break at 260 pounds than the Quest Link that inconvenienced Zack.

We don't wanna use anything - line loop, Shear Link, Tost weak link - which WILL blow at a TESTED VALUE, plus or minus ten percent. We want something that will LIKELY blow at TWICE LINE TEST STRENGTH. And:
- if it blows when nothing's going on and/or you really don't want it to then, hell, you probably just didn't tie it very well
- after six blows in a row, hell, just double it and inform Russell so that he knows the equation has been changed