Weak links

[Tad Eareckson]

Hey Trisa...

Dr. Trisa Tilletti - 2012/06

Jim Lee, two-time US Hang Gliding National Champion and six-time US comp point champion, was our commercial pilot sailplane instructor. He is a sailplane distributor, instructor, and tow pilot in Florida. He recently told us that he has only seen two sailplane weak link breaks, and experienced one himself, when he and the tow plane had to turn sharply on tow to avoid a helicopter that flew into their flight path. He said that his weak link performed properly in that situation.

With a legal range of eighty to two hundred percent max certified operating weight, what rating do you use in order for your weak link to perform properly in that situation?

[Tad Eareckson]

The FAA is fucking over sailplanes and, since 2004/07/27, us the same way USHGA's been fucking over hang gliders since the early Eighties.

CFR 91.309(a)(3)

(3) The towline used has a breaking strength not less than 80 percent of the maximum certificated operating weight of the glider or unpowered ultralight vehicle and not more than twice this operating weight. However, the towline used may have a breaking strength more than twice the maximum certificated operating weight of the glider or unpowered ultralight vehicle if--

(i) A safety link is installed at the point of attachment of the towline to the glider or unpowered ultralight vehicle with a breaking strength not less than 80 percent of the maximum certificated operating weight of the glider or unpowered ultralight vehicle and not greater than twice this operating weight; and

(ii) A safety link is installed at the point of attachment of the towline to the towing aircraft with a breaking strength greater, but not more than 25 percent greater, than that of the safety link of the towed glider or unpowered ultralight vehicle end of the towline and not greater than twice the maximum certificated operating weight of the glider or unpowered ultralight vehicle.

- Using a towline as a weak link is moronic.
- NOBODY:
-- calls a weak link a "safety link" - it's stupid and misleading
-- with half a brain or better uses a:
--- sailplane weak link under 1.3 Gs
--- hang glider weak link under 1.4 Gs
--- paraglider weak link much under 2 Gs

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. Two possibilities are stalling the glider, or dragging a wingtip on the ground during a low altitude turn and cartwheeling the glider.

Situation 1. If the towrope breaks or is inadvertently released prior to the towplane's liftoff, the standard procedure is for the towplane to continue the takeoff and clear the runway, or abort the takeoff and remain on the left side of the runway. If the towplane loses power during the takeoff, the towpilot should maneuver the towplane to the left side of the runway. If the glider is still on the runway, the glider pilot should pull the release, decelerate using the wheel brake, and be prepared to maneuver to the right side of the runway. Pulling the towrope release in either case ensures that the rope is clear of the glider. Since local procedures vary, both the glider and towpilot must be familiar with the specific gliderport/airport procedures.

Situation 2. This situation occurs when both the towplane and glider are airborne and at a low altitude. If an inadvertent release, towrope break, or a signal to release from the towplane occurs at a point in which the glider has insufficient runway directly ahead and has insufficient altitude to make a safe turn, the best course of action is to land the glider straight ahead. After touchdown, use wheel brake, as necessary, to slow and stop as conditions permit. At low altitude, attempting to turn prior to landing is very risky because of the likelihood of dragging a wingtip on the ground and cartwheeling the glider. Slowing the glider as much as possible prior to touching down and rolling onto unknown terrain generally is the safest course of action. Low speed means low impact forces, which reduce the likelihood of injury and reduce the risk of significant damage to the glider.

Situation 3. If an inadvertent release, towrope break, or a signal to release from the towplane occurs after the towplane and glider are airborne, and the glider possesses sufficient altitude to make a 180° turn, then a downwind landing on the departure runway may be attempted.

The 180° turn and downwind landing option should be used only if the glider is within gliding distance of the airport or landing area. In ideal conditions, a minimum altitude of 200 feet above ground level is required to complete this maneuver safely. Such things as a hot day, weak towplane, strong wind, or other traffic may require a greater altitude to make a return to the airport a viable option.

The responsibility of the glider pilot is to avoid the towplane or other aircraft. If the tow was terminated because the towplane was in distress, the towpilot is also dealing with an emergency situation and may maneuver the aircraft abruptly.

After releasing from the towplane at low altitude, if the glider pilot chooses to make a 180° turn and a downwind landing, the first responsibility is to maintain flying speed. The pilot must immediately lower the nose to achieve the proper pitch attitude necessary to maintain the appropriate approach airspeed.

Make the initial turn into the wind. Use a medium bank angle to align the glider with the landing area. Using too shallow a bank angle may not allow enough time for the glider to align with the landing area. Too steep a bank angle may result in an accelerated stall. If the turn is made into the wind, only minor course corrections should be necessary to align the glider with the intended landing area. Throughout the maneuver the pilot must maintain the appropriate approach speed and proper coordination.

Downwind landings result in higher groundspeed due to the effect of tailwind. The glider pilot must maintain the appropriate approach airspeed. During the straight-in portion of the approach, spoilers/dive breaks should be used as necessary to control the descent path. Landing downwind requires a shallower than normal approach. Groundspeed will be higher during a downwind landing and especially noticeable during the flare. After touchdown, spoilers/dive breaks, and wheel brakes should be used as necessary to slow and stop the glider as quickly as possible. During the later part of the roll-out, the glider will feel unresponsive to the controls despite the fact that it is rolling along the runway at a higher than normal groundspeed. It is important to stop the glider before any loss of directional control.

Situation 4. When the emergency occurs at or above 800 feet above the ground, the glider pilot may have more time to assess the situation. Depending on gliderport/airport environment, the pilot may choose to land on a cross runway, land into the wind on the departure runway, or land on a taxiway. In some situations an off gliderport/airport landing may be safer than attempting to land on the gliderport/airport.

Situation 5. If an emergency occurs above the traffic pattern altitude, the glider pilot should maneuver away from the towplane, release the towrope if still attached, and turn toward the gliderport/airport. The glider pilot should evaluate the situation to determine if there is sufficient altitude to search for lift or if it is necessary to return to the gliderport/airport for a landing.

Figure 7.5. Situations for towline break, uncommanded release, or power loss of the towplane.

1. Very low altitude, premature release/rope break with runway still available. Land on runway, use wheel break to stop. If necessary alter course to the right to avoid towplane.

2. Very low altitude, premature release/rope break with insufficient runway available.

3. Above 200 ft. if suitable, turn into wind, make 180° turn, land downwind.

4. At higher altitudes, multiple options are usually available.

AEROTOW CLIMB-OUT AND RELEASE PROCEDURES

Once airborne and climbing, the glider can fly one of two tow positions. High tow is aerotow flight with the glider positioned above the wake of the towplane. Low tow is aerotow flight with the glider positioned below the wake of the towplane. [Figure 7-6] Climbing turns are made with shallow bank angles and the glider in the high tow position.

High tow is the preferred position for climbing out because the glider is above the turbulence of the towplane wake. High tow affords the glider pilot an ample view of the towplane and provides a measure of protection against fouling if the towrope breaks or is released by the towplane because the towrope falls below the glider in this position.

Low tow offers the glider pilot a better view of the towplane, but puts the glider at risk from towrope fouling if the towrope breaks or is released by the towplane. Low tow is used for cross-country and level flight aerotows.

During level flight aerotows, positioning the glider above the wake of the towplane has several disadvantages. One is that the towplane wake is nearly level rather than trailing down and back as it does during climbing aerotow operations. Because the towplane wake is nearly level, the glider must take a higher position relative to the towplane to ensure the glider stays above the wake. This higher position makes it difficult to see the towplane over the nose of the glider. Easing the stick forward to get a better view of the towplane accelerates the glider toward the towplane, causing the towrope slack. Positioning the glider beneath the wake of the towplane in level flight offers an excellent view of the towplane, but the danger of fouling from a towrope failure or inadvertent release is greater when flying in the low tow position.

Causes of "takeoff emergencies":
- towrope break
- inadvertent towrope release
- towplane loses power
- uncommanded release
- power loss of the towplane
- signal to release from the towplane
- towplane in distress
- premature release
- release by the towplane
- towrope failure
- inadvertent release

But you can't have a takeoff emergency as a consequence of a 0.8 G weak link blow because it's a "safety link" - mandated by the FAA in the range the FAA has determined will keep the glider "safe".

This is EXACTLY the same bullshit we see in hang gliding.

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

Jim Rooney - 2011/09/02 23:09:12 UTC

Yeah, damn those pesky safety devices!
Remember kids, always blame the equipment.

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

Jim Rooney - 2013/03/05 19:42:58 UTC

My god my head hurts.

Wow...
So you know what happened then?
OMG... thank you for your expert accident analysis. You better fly down to FL and let them know. I'm sure they'll be very thankful to have such a crack expert mind on the case analyzing an accident that you know nothing about. Far better data than the people that were actually there. In short... get fucked.

Again, tell me how all this nonsense is about "safety"?

So, a stronger weaklink allows you to achieve higher AOAs... but you see high AOAs coupled with a loss of power as *the* problem? So you want something that will allow you to achieve even higher AOAs?
Are you NUTS?

I'm tired of arguing with crazy.
As I said many times... there are those that listen with the intent of responding... you unfortunately are one.

You've done a great job of convincing me never to tow you.
Thank you for that.
Mission accomplished.

[Tad Eareckson]

Dr. Trisa Tilletti - 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. 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.

Well yeah, but...

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 exist in the big, real world.

That's under LAB conditions - which cannot completely include all the factors and variability that exists in the big, real world. So shouldn't we take the test values, double them, and declare the tolerances to be plus or minus four ounces - in keeping with the method we use for determining the installed loop figures?

[Tad Eareckson]

Dr. Trisa Tilletti - 2012/06

There are other factors that affect weak link performance.

Which, of course, is the reason we can't determine their big, real world breaking strengths under lab conditions. The best we can do is look at the averages of our lab test results, ignore the deviations, and multiply by two.

Faster tows create more drag, which increases load on the weak link, and makes the turbulence impart a sharper impact load on the weak link.

And, of course, the glider.

http://www.chgpa.org/forums/viewtopic.php?f=2&t=3661
Flying the 914 Dragonfly

Jim Rooney - 2008/12/06 20:01:49 UTC

You will only ever need full throttle for the first fifty feet of a tandem tow. Don't ever pull a solo at full throttle... they will not be able to climb with you. You can tow them at 28 mph and you'll still leave them in the dust... they just won't be able to climb with you... weaklinks will go left and right.

http://www.hanggliding.org/viewtopic.php?t=14312
Tow Park accidents

Jim Rooney - 2009/11/10 17:19:54 UTC

Ah, back to civil discussion.

Something to note about leaving carts....
There is a drastic difference when being pulled by a 582 or a 914/912.

People have a tendency to leave the cart too soon when behind a 582. With the big tugs however, the problem is the opposite. This is especially obvious when you take someone that tows behind 582s and put them behind a 914.

It doesn't sound like a problem at first... more speed is good right? As with all things, yes but .... "to a point". See what happens behind a 914 if you use 582 technique is this....

You accelerate very rapidly of course and gain a lot of speed. I call it leaving the cart at Mach 5. No problem yet (well, there's a small one, but we'll get to that). As you leave the cart, the tug is already a good bit above you, so you ease off the bar pressure (you've got a ton at this point) and this is just about the same time you slam into the prop wash. Your weaklink lets go.

After a couple weaklink breaks in this manner, you start to wonder if Tad's right about these "weak" weaklinks. Nevermind that it's a technique problem not an equipment problem. Nevermind that using a stronglink greatly increases the chances that you will hurt yourself in a very bad way.

See, weaklinks don't care about speed. They care about load. Going Mach5 and easing off the pitch, even a little bit, greatly increases your load... remember that whole bit about windspeed being an exponential factor?

So there you are with in a highly loaded situation, and then you shockload the system by hitting the propwash. Not good.

Your weaklink is doing exactly what it should do.

Behind a 914, set the cart correctly, resist getting "pulled through" the bar by the tow force, and allow the glider to simply fly out of the cart. Don't pull in. Don't lock yourself to the cart. In short, don't use 582 technique. Consult an instructor (that's familiar with 914s) for a more detailed explanation than this.

Behind a 582, the problem is as stated before... people get antsy to get out of the cart. You do roll till you're practically lift the cart. It's a very different world.

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

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

See, in truck towing, a weaklink does next to nothing for you (unless the line snags).
This is because you're on a pressure regulated system... so the forces never get high enough to break the link.

This is not the case with an aerotow.
This is why the weaklink exists.

The forces of an aerotow can get high enough to tear the wings off the glider.
This is no exaggeration... it can be done.

This is why all gliders need to use single loops of 130 pound Greenspot on their gliders, Pre-Tied such that it breaks inconsistently at 130 pounds (towline: 260 pounds one point, 226 pounds two point) or Wrapped and Tied such that it breaks consistently at 260 pounds (towline: 520 pounds one point, 452 pounds two point).

Gotta be absolutely certain that we don't...

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

Jim Rooney - 2013/03/07 06:40:02 UTC

So... if it's *only* purpose is to prevent your glider from breaking apart... which is complete and utter bullshit... but if that was it's only purpose... why then do we have them at all?
Your glider will tear the rope apart before it breaks.
It will tear the towmast off the tug before it breaks.
Your glider is capable of amazing feats of strength... it is in no danger of folding up on you.

...tear the wings off that glider - especially when we hit that 914 propwash when we're doing Mach 5 takeoffs.

Higher climb rates and climb angles impart more load on the weak link...

You mean like THIS:

http://www.youtube.com/watch?v=Jm-YPa_Gvdw


http://farm3.staticflickr.com/2928/14397296584_1d0e5e389b_o.png
10-03323

He's probably using a really dangerous stronglink. He should be using a proper weak link to...

http://www.youtube.com/watch?v=WFAPpz6I6WU

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


...make sure he doesn't stress out his glider.

...as does towing in a position that is too high or low, or too far to the side, rather than in the center of the cone of safety.

But only a total fucking idiot...

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

Mark Frutiger - 2013/02/08 19:12:21 UTC

Zack hit the lift a few seconds after I did. He was high and to the right of the tug and was out of my mirror when the weak ling broke. The load on the tug was not excessive as with a lockout, but I was not surprised when the weak link broke. I was still in the thermal when I caught sight of Zack again. I did not see the entry to the tumble, but I did see two revolutions of a forward tumble before kicking the tug around to land. The thermal was still active in the area that I had just launched from so I did a go round and landed on a runway 90 degrees cross to the direction we were towing in.

...would stray very far from the center of the Cone of Safety. And he wouldn't likely be on tow and outside of the Cone of Safety for very long because Russell Brown, Paul and Lauren Tjaden, and Mark Frutiger...

http://ozreport.com/forum/viewtopic.php?t=24534
It's a wrap

Lauren Tjaden - 2011/08/01 02:01:06 UTC

For whomever asked about the function of a weak link, it is to release the glider and plane from each other when the tow forces become greater than desirable -- whether that is due to a lockout or a malfunction of equipment or whatever. This can save a glider, a tow pilot, or more often, a hang glider pilot who does not get off of tow when he or she gets too far out of whack.

...make sure everyone's got a weak link to save him when he does not get off of tow when he gets too far out of whack.

Towing without a fin decreases directional stability and smoothness of the tow, which increases load and wear on the weak link.

So...

http://www.ushpa.aero/safety.asp
USHPA - Safety Articles

Fatality Reports
2013/02/02 - Zack Marzec

Zack Marzec (27), an H-4 Pilot with Aero Tow and Tandem Aero Tow proficiency as well as Advanced Instructor and Tandem Instructor appointments, and a USHPA member since 2009, suffered fatal injuries when when his glider tumbled during an aero tow launch. During the launch, at an altitude of 150 AGL, the pilot encountered an invisible bullet thermal which pitched the nose up, causing the weak link to break. Upon the breakage of the weak link, the glider whip stalled and then tumbled twice. The pilot and glider's leading edge hit the ground simultaneously. The pilot was utilizing his own pro-tow style tow harness, this own high performance glider with VG on, and was not wearing a full face helmet.

...how come you didn't make sure that the absence of a fin was noted as an issue in this fatality report? And it's never too late to bring it to everyone's attention. Hell, if he had just had a fin it wouldn't have mattered what kind of helmet he was using.

Likewise, pro-towing decreases smoothness and the ability to control the tow and can increase loads on the weak link, as described earlier.

Yeah. Pro toads tend to use short Spectra bridles which don't have the shock absorbency of the long polypro three point bridles Russell recommends and thus act somewhat like an impact wrench on the 130 pound Greenspot and hinder it in its ability to perform its primary and most essential function of not breaking - which is the same expectation you have of the weak links you use in...

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.

...sailplaning.

These factors lead to a relatively high frequency of weak link breaks at aerotow hang gliding competitions.

Yeah. Fast tows creating more drag, turbulence imparting sharper impact loads, higher climb rates and angles, towing outside of the center of the Cone of Safety, pro-towing and not using fins to increase directional stability and smoothness...

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


It all adds up to weak links breaking...

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

Davis Straub - 2011/08/26 14:04:52 UTC

We had six weaklink breaks in a row at Zapata this year. Russell Brown (tug pilot, tug owner, Quest Air owner) said go ahead and double up (four strands of Cortland Greenspot). He knows I used his Zapata weaklink in Big Spring (pilots were asked to tell the tug pilot if they were doing that).

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.

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

Davis Straub - 2013/02/09 16:45:39 UTC

I am more than happy to have a stronger weaklink and often fly with the string used for weaklinks used at Wallaby Ranch for tandem flights (orange string - 200 lbs). We used these with Russell Brown's (tug owner and pilot) approval at Zapata after we kept breaking weaklink in light conditions in morning flights.

...inconsistently at a relatively high frequency. Sometimes the frequency of breaking weak links inconsistently is so high that...

There has been a trend lately for some tandem operators to go with about a 400 lb. weak link on both the tandem glider and tug V-bridles, rather than 520 lbs., to help protect the equipment from large stresses. If tandem operators think that, practically, a 520 lb. double loop weak link is too much for a tandem, it is way too much for a solo pilot.

Solo hang glider pilots should not place a 520 lb. double loop weak link on their V-bridle, unless they get specific approval from the tow operator. It could be hard on the equipment and could be illegal if the tug is using a weaker weak link. It is also far beyond USHPA's nominal 1g recommendation.

...tandem operators stop thinking that practically:
- a 520 pound double loop weak link:
-- isn't way too much for a solo pilot
-- won't be hard on the equipment

- he doesn't give any more of a rat's ass about illegally towing a solo with a heavier weak link than the tug's than he does about illegally towing a tandem with a heavier weak link than the tug's

An inadvertent weak link break places a pilot at a competitive disadvantage and can increase the chance of personal injury or damage to their glider--which is also a competitive disadvantage.

But these are only issues for competition pilots flying at competitions. And anyway...

http://ozreport.com/16.078
The Rob Kells Meet

Davis Straub - 2012/04/18 15:02:09 UTC

Mitch Shipley (T2C 144) crashed at launch after a weak link break. He tried to stretch out the downwind leg and then drug a tip turning it around and took out his keel (at least).

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.

http://www.hanggliding.org/viewtopic.php?t=18777
Accident - Broken Jaw - Full Face HG Helmet

Keith Skiles - 2010/08/28 05:20:01 UTC

Last year, at LMFP I saw an incident in aerotow that resulted in a very significant impact with the ground on the chest and face. Resulted in a jaw broken in several places and IIRC some tears in the shoulder.

http://www.hanggliding.org/viewtopic.php?t=27396
Scooter tow faillure... or Never Land On Your Face

Mitch Shipley - 2012/10/22 19:04:16 UTC
USHGA Accident Reporting Committee Chairman

We engage in a sport that has risk and that is part of the attraction.

...the risks of trashing your glider and demolishing your body are what really make this sport enjoyable and worth pursuing.

[Tad Eareckson]

Hey Trisa...

Dr. Trisa Tilletti - 2012/06

Actually, that is our expectation of performance for weak links on hang gliders here at Cloud 9, too. Primarily, we want the weak link to fail as needed to protect the equipment, and not fail inadvertently or inconsistently. We want our weak links to break as early as possible in lockout situations, but be strong and reliable enough to avoid frequent weak link breaks from turbulence. It is the same expectation of performance that we have for the weak links we use for towing sailplanes.

But LOOK:

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

Mark Frutiger - 2013/02/08 19:12:21 UTC

Zack hit the lift a few seconds after I did. He was high and to the right of the tug and was out of my mirror when the weak ling broke. The load on the tug was not excessive as with a lockout, but I was not surprised when the weak link broke. I was still in the thermal when I caught sight of Zack again. I did not see the entry to the tumble, but I did see two revolutions of a forward tumble before kicking the tug around to land. The thermal was still active in the area that I had just launched from so I did a go round and landed on a runway 90 degrees cross to the direction we were towing in.

The weak links Mark Frutiger is towing do the PRECISE OPPOSITE! In a lockout the load is excessive and when Zack Marzec was dealing with turbulence with the expectation that his weak link be strong and reliable enough to avoid frequent breaks from turbulence he has a frequent break from turbulence with a load NOT excessive as with a lockout.

And this frequent inadvertent weak link break...

These factors lead to a relatively high frequency of weak link breaks at aerotow hang gliding competitions. An inadvertent weak link break places a pilot at a competitive disadvantage and can increase the chance of personal injury or damage to their glider--which is also a competitive disadvantage.

...results in him being personally injured (REALLY personally injured - he didn't make it to the hospital) AND his glider was damaged. And it's a DAMN GOOD THING that that didn't happen at an aerotow hang gliding competition because BOTH of those issues (personal injury in the same inadvertent weak link break incident as damage to the glider - who'da thunk / what are the odds) would've almost certainly put him at a serious competitive disadvantage.

So what percentage of weak links Mark's towing do you think are Wrap and Tie jobs? Seeing as how this is Quest...

It's not that it doesn't happen, but it is a rare occurrence. Russell Brown, a founder of Quest Air in Florida and a well-known Dragonfly tug pilot, is also a sailplane pilot, tug pilot, and A&P mechanic for a large commercial sailplane towing operation in Florida. He told us that, like us, he has never seen a sailplane weak link break, either. Russell owned the first 914-powered Dragonfly ever made--he helped us build the second one, which we still fly. He is the one who, many years ago, showed us the method for making a WT weak link and suggested we use polypropylene rather than Spectra for hang glider V-bridles.

...I'd guess it's pretty high.

So is there some kind of evidence that Wrap and Tie weak links are better meeting your expectations than the Pre-Tied crap that Zack was using that broke frequently from turbulence in line with Mark's expectations?

Why is it that after all the work you put into your "Higher Education" article just eight months prior nobody in any of the discussions - including Russell Brown, Paulen Tjaden, Mitch Shipley, Jim Rooney, Ryan Voight, Davis Straub, Steve Wendt, William Olive, Brad Gryder, Mark Knight, Matt Taber, Jack Axaopoulos - suggested that Zack's chintzy Pre-Tied weak link might have been an issue and a proper Wrapped and Tied Cloud 9 weak link might have been a solution?

How come YOU haven't said anything? How come this isn't now mandatory in the SOPs? Are you planning on writing a fourteen page told-ya-so article for the magazine now that the season's winding down?

Or...

http://www.hanggliding.org/viewtopic.php?t=27736
Increase in our USHpA dues

Mark G. Forbes - 2012/12/20 06:21:33 UTC

We're re-working the accident reporting system, but again it's a matter of getting the reports submitted and having a volunteer willing to do the detail work necessary to get them posted. There are also numerous legal issues associated with accident reports, which we're still wrestling with. It's a trade-off between informing our members so they can avoid those kinds of accidents in the future, and exposing ourselves to even more lawsuits by giving plaintiff's attorneys more ammunition to shoot at us.

Imagine a report that concludes, "If we'd had a procedure "x" in place, then it would have probably prevented this accident. And we're going to put that procedure in place at the next BOD meeting." Good info, and what we want to be able to convey. But what comes out at trial is, "Ladies and Gentlemen of the Jury, my client suffered injury because USHPA knew or should have known that a safety procedure was not in place, and was therefore negligent and at fault." We're constantly walking this line between full disclosure and handing out nooses at the hangmen's convention.

...is this just such an obvious and easy fix that if you brought it to everyone's attention you'd be opening a lot of people up to liability issues?

[Tad Eareckson]

http://ozreport.com/3.068
Weaklinks, is there no shame?

Davis Straub - 1999/06/10

As I don't want the Oz Report to turn into the Weaklinks Report...

Then try to get the fuckin' THEORY right, use them for the only safe function they can fulfill...

http://ozreport.com/forum/viewtopic.php?t=24534
It's a wrap

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

To break under load before the glider does.

...to break under load before the glider does, and stop...

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.

...trying to use them as...

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.

...as emergency releases.

I'll try to make this my last weaklink article for a while (the last article was my "strong links" article - although it appears as though many of my less careful readers didn't appear to "get" it.)

No Davis, we "got" it. A "strong link" is...

http://ozreport.com/3.066
Weaklinks

Davis Straub - 1999/06/06

A few weeks later I was speaking with Rhett Radford at Wallaby Ranch about weaklinks and the issue of more powerful engines, and he felt that stronger weaklinks (unlike those used at Wallaby or Quest) were needed. He suggested between 5 and 10 pounds of additional breaking strength.

...five or ten pounds heavier than a standard aerotow weak link. Any more than that and the Dragonfly is at serious risk of stalling - unless, of course, the glider's a tandem. Then you can use twice solo before the Dragonfly can be stalled.

Peter Birren, who was indeed not one of those less careful readers, writes:

PETER BIRREN!!! He's got an NAA Safety Award! I can hardly wait to hear what he has to say!

We here in the Chicago area, at least the static tow pilots...

All permanently stuck in 1983 Hewett based hell...

...have done an extensive testing of various string weaklinks and materials. We've found what, to us, is the ultimate all-around stuff: 130# test braided dacron kite string from Catch the Wind Kites (1-800/227-7878). A 1000' roll costs $15.99 + $4.00 S&H.

Think how many downtubes you could break with that!

Tied with a grapevine knot, a single loop has a break strength of almost the full line strength...

Yes. ALMOST the FULL LINE STRENGTH. 130 pounds - like everybody else who ACTUALLY TESTS it gets. NOT the 260 pounds Quest and the douchebags at Ridgely - who fired up their operation thirteen days prior with them going off like popcorn - are telling everybody.

...and is good for the keel release setup.

Oh REALLY, Peter.

- The keel release setup for WHAT GLIDER? All of them?

- What's it good for? Meeting your expectation of breaking as early as possible in lockout situations but being strong and reliable enough to avoid frequent breaks from turbulence?

A double loop (4-strand) for static towing breaks at 230-240# as measured with a calibrated pressure gauge at the car.

Did you hide the knot properly? The guys who hide the knot all swear it blows at 520.

The heavier guys use the 150# stuff.

Doesn't that put the guy driving the truck at unreasonable risk? Wouldn't that virtually guarantee a stall? And shouldn't we all be playing by the same rules?

Cost comes out to all of $.03 for each 18" long segment that we tie up.

Here's the glider of a guy who flew at about 255 pounds and used a single loop of 130 on a one point bridle - which, we agree, would have put him at around 260 towline.



What do you figure it would cost to replace that leading edge section and get that baby back on the flight line?

I can cut and tie 100 weaklinks in an evening while watching TV. That's enough for a full season for me plus figuring I'll give out a few at a site.

When I'm set up for production I can do one Bridle Link in maybe twenty minutes. And one of those will last most tow pilots an entire career.

And as we use a new one for each tow (using the Linknife to cut 'em, of course) we're assured of using one that's fresh.

And thus will meet your performance expectations almost perfectly - give or take five pounds or so.

The same strings, tied with a square knot (and 2 half-hitches to lock 'em), break about 30 pounds less. We started out using 110# line but didn't take into account the weight of the towline and some additional drag during the tow. Now the 130# is just right for the average sized pilot/glider.

Idiot.

But anyway, Davis...

Here we are with test results on a single loop of 130 over fourteen years ago that you've published and are consistent with what everybody else who tests - and doesn't try to cook the books like Dr. Trisa Tilletti, Jim Rooney, Mark Knight - gets. The double loop is a bit high but not enough to worry much about.

And here we are earlier this year...

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.

...with you still doing your tireless utmost to sew as much confusion about the function of the weak link and the strength of a loop of 130 as humanly possible. Do all you Industry shits take special training courses on how to do this?

[Tad Eareckson]

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

Bill Cummings - 2011/08/28 23:18:41 UTC

I viewed pictures of Tad's bench testing machine (for the lack of me coming up with a better word for it.) but no where did I see or read where Tad packed a barrel release with slushy snow stuck it in the freezer and bench test how many lbs of pull it would take to overcome the ice and then release.

While no one was bench testing frozen releases at Wallaby and Quest we were field testing releases during the Minnesota winter. We never came across any reliable winter release. (But one---)

It would seem quite apparent that not being able to release we all must have eventually over flown the towline, locked out, and died many times over right?

If we had had a 2 "G" weak-link we would have certainly died.

Why?

The back of the snow machine would have lifted up enough to lose traction and eventually the pilot would enter a lock-out. (The driver releasing two thousand feet of line would not be the answer either since it's too much drag.)

Next it would be time for letting go of the bar and trying the big mitten and hook knife fiasco ---you would think --- but we skipped over that step.

We all lived because there was only one reliable release that NEVER failed us and allowed us to keep both hand on the bar and never relinquish control.

What was the name of this release?

It was called: WEAK-LINK!

001-00000
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http://www.hanggliding.org/viewtopic.php?t=14312
Tow Park accidents

Jim Rooney - 2009/11/10 17:19:54 UTC

Ah, back to civil discussion.

Something to note about leaving carts....
There is a drastic difference when being pulled by a 582 or a 914/912.

People have a tendency to leave the cart too soon when behind a 582. With the big tugs however, the problem is the opposite. This is especially obvious when you take someone that tows behind 582s and put them behind a 914.

It doesn't sound like a problem at first... more speed is good right? As with all things, yes but .... "to a point". See what happens behind a 914 if you use 582 technique is this....

You accelerate very rapidly of course and gain a lot of speed. I call it leaving the cart at Mach 5. No problem yet (well, there's a small one, but we'll get to that). As you leave the cart, the tug is already a good bit above you, so you ease off the bar pressure (you've got a ton at this point) and this is just about the same time you slam into the prop wash.

011-02800
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Your weaklink lets go.

After a couple weaklink breaks in this manner, you start to wonder if Tad's right about these "weak" weaklinks. Nevermind that it's a technique problem not an equipment problem. Nevermind that using a stronglink greatly increases the chances that you will hurt yourself in a very bad way.

See, weaklinks don't care about speed. They care about load. Going Mach5 and easing off the pitch, even a little bit, greatly increases your load... remember that whole bit about windspeed being an exponential factor?

So there you are with in a highly loaded situation, and then you shockload the system by hitting the propwash. Not good.

Your weaklink is doing exactly what it should do.

015-02819
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http://ozreport.com/forum/viewtopic.php?t=24846
Is this a joke ?

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

Zach, you can nit pick all you like, but I'll put a 100,000+ flight record over your complaints any day of the week.

Let me see if I can clear up a few things for ya.
A lot of this I sent to Steve btw...

The "purpose" of a weaklink is not in question. Your semantics are.
The "purpose" of a weaklink is to increase the safety of the towing operation. PERIOD.

There are many ways in which it accomplishes this.
You're nit picking over what you call the "true purpose"... but all you're griping about is a definition... and an erroneous one at that.

Again, The weak link increases the safety of the tow.

This is why the weaklink exists.

The forces of an aerotow can get high enough to tear the wings off the glider.
This is no exaggeration... it can be done.

http://www.hanggliding.org/viewtopic.php?t=13745
Good News vs Sad News

NMERider - 2009/10/01 22:31:04 UTC

We had a Sylmar pilot die from massive head injuries last summer when he got drilled into the ground by sink while he was still prone. His helmet covered head struck a boulder.

And BTW - I cannot rotate my Rotor Kickass harness fully upright but I can pull on plenty of speed by merely keeping both hands on the base tube. Not one up and one down but both hands. If I get drilled by sink at the last second at least the first thing to hit won't likely be my head. In my cocoon harness I can go upright with hands on the DTs and easily get my T2 over 40 mph.

IIRC - Tad has already worn out his welcome on the Oz Report over his AT release mechanism, and so it seems he has come here to preach his gospel of safety according to Tad. The prize of course will either be delivered by the HMS Beagle or can be found on the Gallapagos Islands.

027-03123
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Jim Rooney - 2011/08/26 02:44:10 UTC

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

There are many ways in which it accomplishes this.

044-03623
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045-03625

http://www.hanggliding.org/viewtopic.php?t=22176
Paragliding Collapses

Jim Rooney - 2011/06/12 13:57:58 UTC

Most common HG injury... spiral fracture of the humerus.

http://www.hanggliding.org/viewtopic.php?t=12682
Landing on your feet (for AEROTOW)- So Dangerous

Jack Axaopoulos - 2009/06/29 14:26:26 UTC

OMG!!! You dont even have wheels!!?!?!?!?
YOURE GONNA DIE FOR SUUUUREE!!!!

I have a brilliant idea. People who cant land for sh*t.... LEARN TO LAND That way when a weak link breaks on you, ITS A NON-ISSUE. Genius huh???

http://www.hanggliding.org/viewtopic.php?t=27415
Friday the 19th with Hawks & Friends!

NMERider - 2012/10/24 21:47:05 UTC

I have to say that landing on the wheels is so much fun it's not funny.

047-03703
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http://www.youtube.com/watch?v=B3UbztgTtsc
I Launched Without Buckling into my Harness - a hang gliding film by Greg Porter
03-31006
http://c1.staticflickr.com/9/8394/28993413612_5b4ac915ee_o.png

Greg Porter - 2013/10/02

That was scary, huh? So ya know that I heard the, uh, definition of insanity is to continue to do the same thing and to expect different results.

055-04709
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[Tad Eareckson]

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

Deltaman - 2013/02/08 13:57:01 UTC

Its purpose is not to protect the pilot as every ranches are saying but just to protect the glider from overload.

Davis Straub - 2013/02/08 16:57:42 UTC

All the flight parks that I am aware of are quite aware of this. They tell their pilots that the point of the weak link is save the glider from overload and that they should not rely on the weaklink to save them.

And we've established many times over that this is utter rot. The flight parks are ALL telling their pilots that "the focal point of their safe towing system" is this chintzy loop of fishing line that will dramatically increase their chances of survival in a low level lockout. Reason... All their victims are quite aware - through crash reports, experience, common sense - that they will have no chance of survival with downtube and shoulder mounted actuators and they want to lull them into feeling and believing that what they're doing is actually quite safe.

Even Jim Keen-Intellect Rooney...

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

Jim Rooney - 2013/03/07 06:40:02 UTC

So... if it's *only* purpose is to prevent your glider from breaking apart... which is complete and utter bullshit... but if that was it's only purpose... why then do we have them at all?
Your glider will tear the rope apart before it breaks.
It will tear the towmast off the tug before it breaks.
Your glider is capable of amazing feats of strength... it is in no danger of folding up on you.

...has realized that his crap about needing 130 pound Greenspot to...

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

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

The forces of an aerotow can get high enough to tear the wings off the glider.
This is no exaggeration... it can be done.

...prevent the glider's wings from being torn off by slamming into 914 propwash as it comes out of the cart at Mach 5 behind a 914 Dragonfly has worn dangerously/unsustainably thin.

But let's say that the flight parks actually ARE telling their "pilots" that the "point" of the weak link is save the glider from overload and that they should not rely on the weak link to save them.

Still a load of crap.

The "POINT" of the weak link is to save the glider from overload? Like "POINT" of the towline is to transmit thrust?

Bullshit.

a single item or detail in an extended discussion, list, or text : you ignore a number of important points.
- an argument or idea put forward by a person in discussion: he made the point that economic regulation involves controls on pricing.
- an interesting or convincing idea: you must admit he does have a point.
- (usu. the point) the significant or essential element of what is intended or being discussed: it took her a long time to come to the point.
- [in sing.] [usu. with negative or in questions] advantage or purpose that can be gained from doing something: there was no point in denying the truth | what's the point of having things I don't need?
- relevance or effectiveness.
- a distinctive feature or characteristic, typically a good one, of a person or thing: he has his good points.

The weak link is a COMPONENT of the tow system. It doesn't have a POINT - it has a PURPOSE or FUNCTION. It's not a goddam:
- item or detail in an extended discussion
- argument or idea put forward by a person in discussion
- interesting or convincing idea
- significant or essential element of what is intended or being discussed
- advantage or purpose that can be gained from doing something
- distinctive feature or characteristic

Any motherfucker who talks about the "POINT" of the weak link is feeding his marks a load of crap. He's telling them that the issue really isn't all that well understood or agreed upon and is open to interpretation.

And that's compounded with:

...and that they should not rely on the weaklink to save them.

And you SHOULDN'T *RELY* on the weak link to save you - but it's a real good bet that it WILL. And besides, what else ya got? A hook knife? You can rely on your weak link - the focal point of your safe towing system and instant hands free release - to save you a lot better than you can your hook knife.

You also SHOULDN'T do low level aerobatics but, what the hell, you can get away with them just fine if you know what you're doing.

Someone who ISN'T a duplicitous piece of shit like you, Rooney, Ryan, Matt, Trisa is going to tell you the PURPOSE...

Tost Flugzeuggerätebau

Weak links protect your aircraft against overloading.

Deltaman - 2013/02/08 13:57:01 UTC

Its purpose is not to protect the pilot as every ranches are saying but just to protect the glider from overload.

...of the weak link and equip and train you such that you don't ever get into a situation in which it's needed.

Likewise if some asshole instructor starts explaining to you the POINTS of having parachutes and helmets and why you shouldn't rely on them to save you just turn around and walk away.

[Tad Eareckson]

http://www.hanggliding.org/viewtopic.php?t=30167
bad instuctor

Tim Ward - 2013/10/23 14:22:02 UTC
Mira Loma

A bad instructor...

Brian's thread isn't about a bad instructor. It's about a bad "instuctor" - like the ones with which he started in first grade and has gravitated to ever since. Do try to stay on topic.

...would be one that told you to fly very slowly close to the ground in a gusty wind.

How 'bout one who forced you to aerotow with a loop of 130 pound fishing line that can blow six times in a row on competition gliders (read low tension requirements) in light morning conditions in order to increase the safety of the towing operation?

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

NMERider - 2013/02/19 22:56:19 UTC

I will appreciate that it is the tug pilot's call as to the maximum breaking strength of any so-called weak link system and not mine.

Again...

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Go fuck yourself, Jonathan. Hang gliders are the only reason those goddam Dragonflies exist. We paid:
- for them to get built
- to keep:
-- them fueled and maintained
-- some useless shithead employed to pull us up so we can do what we want and are qualified to

And we have more than enough ass kissing sleazebags handing over the sport and our flying opportunities, gliders, and lives to these brain dead egomaniacal quacks as it is without your help.

Granted, you very obviously don't and never will have the brains to make the call as to the maximum breaking strength of your so-called weak link system but there's an FAA specified legal range that aforementioned brain dead egomaniacal quacks are required to stay in and REAL hang glider and, if there are any, tug pilots wanna stay in the middle of it.

And if the weak link is - as The Great Dennis Pagen has chiseled into granite - the focal point of a safe towing system - it should be the glider's call to determine what it is.

And lemme know when we start crashing the same number of tugs as a consequence of overstrength weak links as we do gliders as a consequence of understrength weak links. When we reach that point we may need to start rethinking things.

[Tad Eareckson]

http://www.hanggliding.org/viewtopic.php?t=30307
1st Aerotows!

Dave Pendzick - 2013/11/11 15:27:53 UTC
Oregon

Had a great time at the Wannabe Ranch this weekend. Thanks to Larry and Tina and the rest of the Dog Mountain crew.

http://www.youtube.com/watch?v=HNXZwfR-MyY

2013/11/11 19:11:21 - 3 thumbs up - Tim Dyer

Walt Conklin - 2013/11/11 15:49:44 UTC
Montana

Very nice Dave and a good recovery from the weak link break. Landings are looking good also.

Thanks for posting your adventure. Keep us updated.

Tom Lyon - 2013/11/11 17:46:02 UTC
Michigan

Very nice! Great job!

Bob Knop - 2013/11/11 18:09:26 UTC
Holland

First time i see a checklist in use on a dolly?

I so do hope every last one of you unbelievably stupid motherfuckers breaks his - and her - fucking neck and rots in hell for two or three dozen eternities or until the gene pool has had an opportunity to recover - whatever comes last.