Weak link question

[brianvh]

Sorry Matthew, I can't stop. I'm addicted.

Tad, won't your variable strength weak links be stronger than the tug's for heavy pilots? This means the pilot will end up with the rope, which is way too annoying. Would you say the tug is using under strength weak links too?

Good research on finding a case where the cart hits a hole and the glider gets dragged off before the link breaks. Not sure I want one stronger than this, though. Even if it broke a little late, I wouldn't want it breaking even later.

[Matthew]

Tad,

You answered the question yourself.

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

The weaklink broke when the cart got stuck and the pilot was not pulled along the ground-- minor injury to pilot.

And again using your made up numbers-- 40,000 safe tows at Ridgely. Weaklinks are used at Ridgley-- 40,000 safe tows using weak links.

I again ask, do you ever read the stuff you write? (This is a rhetorical question-- no need for a three page response.)

And for the record, I did agree with you when this thread came up previously that weak links are not one size fits all-- different strentgh weak links for different wing loadings. However, your contention that weak links are dangerous is ungrounded-- again note the 40,000 safe tows at Ridgley with weak links. Also, there's a stronger weak link at the tug end of the line. If a pilot doesn't use a weak link then there is still the weak link on the tug side of the line. Are you suggesting that this weak link is also pointless?

So, please, just answer this simple question. Do you contend that weak links should be eliminated from Hang Gliding towing operations? Try using the word "yes" or the word "no".

Matthew

[Tad Eareckson]

Brian,

The weak link with which I've been flying blows at about 500 pounds of tow line tension. Yeah, that's about a hundred pounds after the one at the tug end blows, so yeah, I'd get the rope.

That would be definitely be way too annoying - IF - it was ever going to happen. But it's never going to happen.

I am totally confident that I can get myself off the line LONG before my tow line tension gets to over triple ambient.

YOU'RE STILL THINKING OF A 1.4 G WEAK LINK BREAK AS SOMETHING THAT'S GOING TO HAPPEN. Start thinking of it as something that will NEVER happen. I can sympathize - It took me quite some time to get out of the old mind set.

It's exactly like a parachute deployment. If it happens it's gonna be a real pain in the ass. But it never happens.

My original scheme was to dial my weak link strength to just under the tug's. Then I said "Waidaminute. I'm not having some other pilot's decision dictate what I'm gonna do on my end of the line."

Here's what the FAA says on the matter...

>
FAR Part 91.309

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

(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 at the towed glider end of the towline and not greater than twice the maximum certificated operating weight of the glider.
<

(Note that the regulation cannot be complied with if the glider maxes out his weak link.)

Yeah, the tugs are also using understrength weak links. USHPA specifies a 2.0 G weak link limit for the glider. That means that if Karen maxed out her weak link it would blow at about the same time as the one up front.

Paul was flying one of my 1.4 G weak links when the shit hit the fan. The Dragonfly's weak link blew about twenty pounds sooner and he got the rope. That wasn't my fault. That was the tug's fault.

I note also that Carlos had a loop of Greenspot on the end of his two point bridle, locked out, had a release failure, and got the rope. That was also the tug's fault.

The Finger Lakes accident...

Just to get our terms straight... That glider tucked off the cart.

Again - That was an low strength weak link - 243 pounds tow line tension max, low end of the G range.

You have to understand that - within the range of maybe as low as 0.5 up to 2.0 Gs - the weak link strength/rating had ABSOLUTELY ZERO bearing on any aspect of that "tow".

The weak link is there to protect the glider - not the pilot. It couldn't protect the glider 'cause it was too low (as would have been the case of a lockout shortly off the cart). Since the weak link couldn't protect the glider the glider was of no use in protecting the pilot.

Once the nose had touched the ground the relevant part of the show was over.

Matthew,

I'll get to yours ASAP.

[Tad Eareckson]

Matthew,

Thirteen stitches in the lip is only a minor injury when it happens to someone else.

Getting dragged a ways across a nice lawn is not what was gonna get him injured. The sudden stop was what got him injured. And there was no possibility of him getting dragged after the sudden stop.

You do not prevent an accident like that by dumbing your weak link down from 1.22 to 0.60 Gs. You prevent it by using a:

1. cart; and
2. release

which comply with the USHPA SOPs.

Forget the cart. Rewind the tape. Move the brake lever down to the basetube where you've got a couple of fingers on it at all times. What happens?

Forty thousand is the low estimate I got from Sunny earlier this season. I have seen but a tiny fraction of them.

One of that tiny fraction involved Denis Scheele hopping on a shiny new Talon for a demo hop. As he was coming off the cart the weak link failed for the usual no reason. He folded a shiny new downtube.

By my definition that was not a safe tow.

Cragin reported having one pop low, getting a wind shift, and having to land downwind. He got a burned knee out of the deal.

Danny and Bob Koshmaryk have both been in low oscillation situations in which an ill timed weak link break could have been catastrophic. Neither of those launches had any physical consequences but when one is literally hanging on by a thread the flight cannot be considered safe - just lucky.

Both Victor and I have folded downtubes which would have remained intact had we been using adequate weak links.

Now how 'bout you (or anyone else) giving me a Ridgely flight in which a weak link break had a POSITIVE effect.

With respect to the front end...

Jim was landing to the east when a taxiing single engine illegally turned off the runway underneath his path and caught the carabiner with the prop.

Yeah, you need a weak link at the front end. The problem is that the placement of the Dragonflies' weak links allows for the possibility of a bridle wrap following a pop. So they're not protected in accordance with the Skyting Criteria and USHPA SOPs.

With respect to your last paragraph... Please go back to the middle of the post I submitted prior to your posing it and tell me what it says in BIG BLACK CAPITAL LETTERS.

[brianvh]

Tad;
I've got to clear up something I don't understand in your thinking:
------------------
">
And let's not forget Paul Tjaden who would have been screwed by a stronger weak link.
<
NO. WRONG. INVALID.

He broke a weak link at about 1.3 Gs of tension. Let's give him a 3.0 G link. Tell me how he gets screwed?

Paul was flying one of my 1.4 G weak links when the shit hit the fan. The Dragonfly's weak link blew about twenty pounds sooner and he got the rope. That wasn't my fault. That was the tug's fault.

I note also that Carlos had a loop of Greenspot on the end of his two point bridle, locked out, had a release failure, and got the rope. That was also the tug's fault."
------------------------

What do you mean it was the tug's fault? The tug pilot should have released? The weak link at the tug end should have been stronger? (not good for Carlos!) I don't know anything about being a tug pilot, but isn't it asking a lot to keep two aircraft under split second surveillance at all times?

I also wish you wouldn't refer to incidents described in whole different unspecified threads at unspecified times. Grows wearisome. I have no idea what the Carlos incident is. We're not all obsessing over this stuff the way you are.

[Tad Eareckson]

Yeah, the tugs are not geared to let us use anything much better than the one size fits all crap. Paul and I should be able to fly at 1.4 (or - if you really wanna push the issue - 2.0) without having to worry about getting the rope.

I think if you know anything about being a towed pilot you know enough about being the tow pilot for the purposes of this discussion.

No - I don't think it's asking to much for both or either pilot(s) to keep those planes under split second surveillance at all times. It's absolutely mandatory until you get a little air under you. But a few seconds away from the runway you can afford to dope off a little 'cause there's not much that can go seriously wrong after that.

That's how come I have no problem with Paul playing with his VG under those circumstances. Things got way out of control instantly but - what the hell - he was weak link protected and high enough for the thing to function as it's supposed to.

With respect to Carlos...

That reference was self contained. My point was that if the tug isn't operating enough in accordance with the SOPs even to prevent a glider using a weak link which limits the tow line tension to 243 pounds, you're not gonna get any less rope than Paul did.

The Carlos incident occurred 2008/06/02 at the ECC and I reported on it 2008/07/29 in the Zapata thread after Paul's lockout.

If it's wearisome - hell, skip it. But I've got the data to support what I'm saying.

[Matthew]

Tad,

You inablility to answer a question with a simple answer is astounding. And, yes, that is a dig.

So, you agree that weak links are necessary. And there is agreement that there should be different wink links for different wing loadings.

No one is being taught to rely on weak links. We all have a release and a back-up release. I have two back up releases. SOP is to release before a lockout or a variety of out of whack on-tow situations. If the primary release fails, go for the secondary. I was taught to go for my hook knife if the secondary fails.

And as you noted, Highland has 40,000 (your number) successful and safe tows.

So, what is the problem???

And, please, try to answer this in one succinct paragraph-- no cutting and pasting and reference to previous posts.

Matthew

[Tad Eareckson]

Matthew,

Nah, I just don't like repeating things I have just made very clear in big black letters for the benefit of folk who can't be bothered to read them the first time.

No, wing loading has nothing to do with it. We're talking glider weight. And by glider weight I mean everything on the cart. But I think that's what you had in mind anyway.

In any case - there is ENORMOUS, GLOBAL, RABID, IDIOTIC resistance to the concept that Karen and Bob Buchanan should be using different strength weak links.

I don't know what people are being taught with respect to reliance on weak links. But I know what they're thinking. They're pretty much all thinking of weak links as lockout protection and that upping strength makes towing more dangerous. And that includes a lot of people WAY up on the pecking order. And people are just about all wrong.

And, in fact, people ARE relying on weak links as lockout protection 'cause most of them have release actuators up where they can't get to them in a real emergency. And most of what's left over have actuators configured such that they can't maintain control of the glider while they're going for them.

As I've said before - anybody who uses a BACKUP release is asking for BIG trouble. There is ZERO excuse for going up with a release that has any more chance of failure than one of one's cross spars.

We have SECONDARY releases ONLY to deal with primary bridle wraps which are not big deals. (But yeah, I know people are taught that those secondaries are backups - (same way they're taught that 0.5 G weak links are 1.0s)).

If the primary release fails and you've got the altitude - roll away and break the weak link. If you release out of sequence with a fore trim point on the keel and your bridle wraps you can break the glider instantly.

Hook knives have no place in the discussion. Don't use secondaries that can fail. In other words - don't use curved pin Baileys.

Forty thousand - AGAIN - is SUNNY'S LOW ESTIMATE. It is not my number.

If the tow ends with a weak link break IT WAS NOT SUCCESSFUL. It was out of control. It did not accomplish the goals of the participants.

And if a weak link breaks below an altitude which permits a normal landing in the field of choice it is not particularly safe tow either.

So far neither you nor anybody else has been able to cite a single instance of a weak link break enhancing the safety of a Ridgely tow. I'm guessing the weak link break rate is around five or ten percent - probably the latter. Humor me and call it FOUR THOUSAND unsuccessful and occasionally dangerous tows. It should be ZERO.

THAT'S THE PROBLEM.

So what I'm trying to do here - primarily - is bring the USHPA to conformity with the FAA and have it codify a minimal safe weak link rating of 0.8 Gs. Personally, I think anything under 1.0 is nuts for hang gliders but I'll take what I can get.

When people start using their brains and realize that the sort of weak link breaks which Kirk described in the long distant opening post of this thread are not just expensive and wasteful but are, in fact, making towing more dangerous - occasionally critically so - this task will become easier.

When I'm talking to Brian I tend to become delusionally optimistic. When I'm talking to you I come crashing back to reality and get even more depressed than usual. How 'bout making my day and acknowledging that we have a problem.

[Matthew]

Tad,

No one is arguing with you regarding different strength weak links for different loads.

Where do you get the idea that people are taught to turn and break the weak link if their primary release fails?

As to secondary releases, things fail. NOTHING IS FOOLPROOF! If your primary release fails, you use your secondary as a back-up.

If a weak link breaks unexpectedly, yes, it's annoying. But so are other things.

Some things are very annoying.

Matthew

[brianvh]

Tad wrote:
"So far neither you nor anybody else has been able to cite a single instance of a weak link break enhancing the safety of a Ridgely tow."

Earlier Janni had written:
"A weak link certainly saved my butt on one occasion. I came off the cart crooked in my Litespeed, over-controlled and would have quickly been in a close-to-ground neck-breaking lockout if the weak link hadn't snapped right away. They can't be weak enough in my humble opinion, especially if you fly sluggish top performers."

To which you responded:
"So how come you didn't release? (Yeah - That's a rhetorical question.)"

I'd call that a brush off. Maybe people themselves fail, or things happen faster than they react, and the weak link may jump in there and save the situation. It improved safety.

Anyway, please stop saying they don't improve safety. Maybe (perhaps surely) we have them too weak and they are hurting safety, but making them too strong will hurt safety too. Maybe the sweet spot is the 1.4 g you like to quote.

If you'd leave it at that and stop saying stuff like
"In the entire history of Ridgely flight ops there would have been no negative consequences if we hadn't [used weak links at all]."

We could perhaps end this discussion right now.

[Tad Eareckson]

Matthew,

No one is arguing with me here and now about using weak links proportional to glider weight. But spend a little time at the flight line at Ridgely and see what's going on. It's a lot more dangerous to take the one size fits all stand on this wire than it was a year and a half ago but you can count the local pilots who've beefed up on one hand.

I never said people are taught to break the weak link if their primary release fails. I'm saying they should be. What they are being taught is dangerous.

But that crap is moot anyway 'cause there's no more excuse for anyone to be going up with a with a release capable of failure than there is to fly with a side wire of similar integrity.

Yeah, my releases are, in fact foolproof. There's no way you or anyone else can get them to fail or propose a scenario in which they will. I've still got that thousand bucks to give substance to the claim.

>
If a weak link breaks unexpectedly, yes, it's annoying.
<

Apparently you either didn't bother to read Danny's post or it completely failed to register.

Brian,

End this discussion right now? I was just getting my second wind.

Janni knows exactly what I'm talking about.

What Matthew, you, and I have in common is an understanding of the importance of being able to be in full control of the glider at all times. And we all use releases that comply with USHPA SOP 12-02.10:B:6 and allow us to maintain that control.

Janni's got a dangerous, noncompliant piece of crap.

He also has a weak link so understrength that it would be illegal if the FAA were running this show.

So HE GOT LUCKY and two wrongs made a right. He was not in control of that situation. He just had the dice stop rolling at the right time.

The weak link that saved his butt in that situation is the same one that's gonna break his freakin' neck in Danny's or Bob's.

>
Maybe people themselves fail, or things happen faster than they react, and the weak link may jump in there and save the situation.
<

If shit happens down low where it matters, the pilot MUST be able to react faster than the weak link. Note Janni didn't say he didn't have TIME to release. He just didn't have the ability to control the situation with one hand on the bar.

When I get on a cart I'm the one in control of the situation. I don't let no fucking piece of string pick, choose, and dictate what's gonna happen next. If I want to stay on - I stay on. If I want off - I get off - at the precise time it's best for ME.

To get off if I'm flying two point I twist my left hand. If I'm flying one I relax my bite.

But I digress...

Right now my goal is to put a 0.8 G floor on the relevant USHPA requirement. Is there anybody out there still stupid enough to object to that?

[Tad Eareckson]

Oops - correction.

While the three of us all have acceptable control of our releases you two are still doing the random number generator thing with respect to your weak links.

[Tad Eareckson]

A few more insomnia induced comments on Janni's Lucky Break...

Janni's flying the supership of Two Thousand A Couple Years Ago.

I'm flying the supership of 1989.

A couple of things happened in the time between.

They made the performance AND the handling a lot better. That used to be oxymoronic.

Nowadays I pretty much always launch with the VG on. And on the HPAT that - by definition - means FULL on.

So I'm guessing NOBODY has anything to tell me about sluggish gliders.

Janni and I hook up at almost EXACTLY the same weights and tow two point and for all but the past two seasons I used the same Magical One Size Fits Karen, Janni, and Me Weak Link. So that makes me a freakin' expert on the range of situations in which that identically loaded alleged 0.76 G weak link will or won't pop.

It'll pop straight, level, centered, and smooth just off the cart and it'll hold long into your worst nightmare of an aerobatic altitude killing lockout.

>
I came off the cart crooked in my Litespeed, over-controlled and would have quickly been in a close-to-ground neck-breaking lockout if the weak link hadn't snapped right away. They can't be weak enough in my humble opinion, especially if you fly sluggish top performers.
<

His second problem WAS NOT that the glider was too sluggish - His second problem was that his glider WASN'T SLUGGISH ENOUGH for the input he was giving it.

The weak link blew WELL before the glider had a chance to start locking out. I repeat - dumb luck.

>
They can't be weak enough in my humble opinion, especially if you fly sluggish top performers.
<

So how come we NEVER hear really small pilots towing really hot gliders one point saying "WHOA! DUDE! This 130 pound Greenspot is WAY too strong! Somebody find me a tea bag."

And how come the FAA says "0.8 G minimum or you don't fly."? Don't they just keep getting safer as they keep getting weaker? And why, in the name of All That Is Holy, would the FAA and USHPA define 2.0 as being acceptable?

[Matthew]

Tad,

You seem to be inventing problems so that you can come up with solutions. And you also seem far more interested in dismissing anything that anyone says that contradicts you and in looking for a worthy opponent. Actions speak louder than words. So if you want to do something actually useful, then focus your efforts on selling your straight pin bailey's to dealers and flight parks, getting USHPA and the flight parks to adopt the use 3 (?)) differrent strength weak links for different loads and promoting the placement of releases within easy reach-- promoting doesn't equate to insulting those who use a release that you don't like. And stop saying your release is foolproff. NOTHING IS FOOLPROOF!

Also, I have a big deadline to deal with today and lots of work at the office the next couple of days. So if I don't respond to you for a few days, don't go accusing me of painting. I hate painting.

Matthew

[Tad Eareckson]

The problems exist, Matthew. The problem with the problems is that they've become so much a part of the landscape that the rabble assumes they're necessary and inevitable components of aerotowing.

---

http://ozreport.com/9.033

---

Weaklinks
2008/11/05 16:25:14
L-Hewett@...
skysailingtowing@yahoogroups.com
#6744

I am sorry I have not been able to participate in the discussion on weak links that has been raging during the last few weeks, but I have been too busy to even read the postings much lest respond to them until now. Let me begin by saying that I personally appreciate Tad Eareckson's efforts to improve the SOP of aerotowing as well as his suggestion to update the Skyting Criteria. It is through efforts like his that progress is made toward safer towing.

Rather than address his and other's comments made during the recent discussion on weak links, let me remind folks that the Skyting Criteria were not developed as a model of a practical towing system. They were proposed for the purpose of defining what an ideal towing system should be in order that towing would be as safe as free flight. The first four criteria are intended to make towing accurately simulate free flight, the next four are to guarantee a safe transition to and from tow, and the last four are to identify some of the safety requirements of practical implementation.

One should remember that no towing system meets all twelve criteria all of the time. Therefore, the purpose of the Skyting Criteria is to help identify when a particular system is deviating from the ideal so that one knows when to be extra cautious and when to make compensations for those deviations.

For example, in the case of aerotowing the second criterion is accomplished by speed control rather than normal tension regulation. As long as the tug and the glider are flying at the same speed the tension remains constant. In general, this speed regulation works great as long as the air is smooth and the two pilots properly cooperate. But anything that causes a differential speed between the two craft will cause the tension to fluctuate, sometimes quite rapidly. Fortunately, the fluctuations are usually quite temporary and rarely reach the excessive values encountered in other forms of towing (such as when a payout winch jams or runs out of line). Nevertheless, compensation must be made for aerotowing's inability to meet criterion two under typical aerotowing conditions. Making the towline longer or more elastic only exasperates the differential velocities, and making it shorter increases the violation of criterion one. So the only practical solution is to recognize that the violation exists and learn to live with it. (I.e. gain sufficient practical experience under a qualified instructor to handle typical thermal conditions and to know instinctively when to release from tow as soon as the situation warrants.)

Now regarding weak links, the whole purpose of a weak link is to release the pilot from tow when he cannot do so himself and the towline tension continues to rise above the limit of safe towing. What that limit is, depends upon many factors, including pilot skill and experience as well as the type of towing and the system being used. I believe everyone recognizes that "one size weak link simply does not fit all".

For example, in the case of an ideal towing system, where the horizontal tension remains constant, a weak link of 0.5 gee will allow the glider to climb at a 30 degree angle, a 1-gee weak link will allow a 45 degree climb angle, and a 2-gee weak link will allow a 60 degree climb angle. These are also the angles a pilot will find himself flying in free-flight when the weak link breaks. Personally, I am not convinced that all hang glider pilots are qualified to recover safely from such extreme aerobatic attitudes. That is why I still recommend a 1-gee maximum weak link when towing horizontally with a good tension controlled system.

However, in the case of aerotowing, where the towline tension may vary as much as +/- 0.25 gee (or even +/- 0.5 gee) when taking off on rough or grassy terrain or when entering and leaving a strong thermal, a 1-gee weak link is going to be breaking much more often than it would on a well-regulated tension system. For most forms of towing, excessive weak link breaks usually constitute nothing more than a minor inconvenience (or a major nuisance). They simply are not a safety issue at all.

However, aerotowing also tends to violate Skyting Criteria twelve (a suitable environment) by frequently towing over terrain that is completely unsuitable for landing. In this case, a weak link break is considerably more than a minor inconvenience. It potentially places the pilot in an extremely dangerous and possibly fatal situation.

Yes, the general rule of towing is, "Get off line at the first sign of danger." However, there are exceptions to this general rule. In fact, I am sure you can imagine more than one situation where getting off line is the worst possible alternative you can take. In such cases, the towline becomes a "lifeline" rather than a "death-line." It pulls you out of danger rather than plunging you deeper into danger. Releasing low over unsuitable terrain is an obvious example of this exception.

Once again, the recognition that aerotowing frequently violates one of the Skyting Criteria requires an appropriate compensation in order to be as safe as possible. In this case, one must use a weak link that simply will not break under reasonable flight conditions and typical flight situations. When one also considers the typical tension variation encountered when aerotowing hang gliders, the conclusion is that the aerotowing weak link should be designed to break in the neighborhood of 1.5 gee (or at least somewhere within the 0.8-gee and 2-gee range specified by the FAA for towing sailplanes).

One also concludes that an aerotow pilot flying with such a weak link should have the skills to recover safely from aerobatic maneuvers greater than 45 degrees - because that is what he may well encounter when the weak link does break.

I believe that the first of these two conclusions is perfectly consistent with the point that Tad has been trying to make. And I thank him for keeping this issue before the hang gliding community.

Donnell

Lionel D. Hewett, Interim Chair
Department of Physics
Texas A&M University-Kingsville
MSC 175 Kingsville, TX 78363-8202

[RedBaron]

Janni's got a dangerous, noncompliant piece of crap.He also has a weak link so understrength that it would be illegal if the FAA were running this show.

The weak link that saved his butt in that situation is the same one that's gonna break his freakin' neck in Danny's or Bob's.

No it won't, because it's so wonderfully understrength. I jerk the base tube and it snaps, I totally dig it! See, being the fat bastard that I am I actually do use a tea bag for a weak link. I know that if I don't use smooth technique and reasonable conditions it will pop. I can't reiterate enough how much I love my tea bag weak link. I feel very Very VERY safe.

Note Janni didn't say he didn't have TIME to release. He just didn't have the ability to control the situation with one hand on the bar.

My bad. Here is saying it for you Tad. I didn't have time to release. I probably wouldn't have released even had I had your mouth release or whatever you use right now. Because I thought I was in control until it broke, which all happened in a fraction of a second, too quick for my level of experience anyway. My tea bag weak link saved my life that day, and I am very Very VERY grateful for that. I will never fly with anything else.

[dbodner]

I'm a complete idiot. I haven't towed in over two years, so I know less, and have less experience, than anyone else in this conversation. But, I wade in nonetheless.

I think most will now agree that the weak link should be scaled to pilot/glider mass and, possibly, skill. But, it seems to me that the difference between an intended weak link break and an unintended weak link break is often bank angle. So, do we need a weak link that varies its strength with bank angle? The more the wings are banked, the the weaker the link. I have no idea how to do that.

I somewhat jokingly imagine an iPhone on my basetube sending signals from its accelerometer via bluetooth to the weak link. I know, far too Rube Goldbergian.

[RedBaron]

I'd like to add if my weak link happens to break for no reason I land, get back on the cart and tow again. BFD!

[brianvh]

Well....

if it just happens to break when you are partially in a low to the ground wingover, it kinda sucks. As Tad says, the tug's pulling you away from the ground, so in many cases you're better off staying with it until you choose your moment to release. They tend to break when stuff is already bad, not before it gets bad.

Or if you're right over a tree line, etc.

[CraginS]

I'd like to add if my weak link happens to break for no reason I land, get back on the cart and tow again. BFD!

And that, ladies and gentlemen, is what started this entire soap opera of a thread! Tad was whining that broken-link pilots at RIdgely get a preferential push to the front of the line to re-launch, delaying his turn to get into the sky.

He wanted them to use stronger weak links, not for purposes of safety, but so they would get the heck out of his way so he can fly when the sky is good.

WE HAVE GONE FULL CIRCLE!

[RedBaron]

if it just happens to break when you are partially in a low to the ground wingover, it kinda sucks. As Tad says, the tug's pulling you away from the ground, so in many cases you're better off staying with it until you choose your moment to release.

Now that just makes no sense to me whatsoever. If you're in a low to the ground wingover with the tug accelerating you you're screwed no matter what (and probably chose to launch in a 90 degree 20 mph peak of the day cross wind). The tug is not pulling you away, it's accelerating you straight into the ground to make a nice crater. And before you disintegrate you wish you would have used a 0.25 g weak link. Come to think of it, I really think that the lighter pilots out there fly with weak links too strong for their total weight.

[Tad Eareckson]

>
Cragin Shelton <cragins@...>
2001/08/08 09:03:01
On Trusting Weak Links

Reading Joe's last item in the lockout thread prompts me to point out a consideration in the discussion:

NEVER TRUST A WEAK LINK!

Expect two things from your weak link:

(1) It will break unexpectedly at the most inopportune time, with no warning adn no indicaiton of a flight problem.

(2) It will hold strong and fast whenever you move into a lockout. You must never plan or expect on a weak link break. It may well not break when you fly with that attitude. As Joe said, if your situation is new to you and not right, get off tow!

I have never had an instructor use those words to me, but all towing instructors I have worked with have given that message in some form. Pagen & Bryden address it clearly in _Towing Aloft_.

...

So, to repeat: Never trust a weak link. Be prepared to fly off tow in a surprise break at all times when attached, and be prepared to hit the release at all times in case of a surprise attitude change.
<

>
2002/08/04 22:14:39
Cragin Shelton <cragins@...>
Eastern Shore Weekend

Set up and watched a bit, then got in line for an aerotow about 1:00. First try was a notably short flight, with a weak link break moments after lifting from the launch cart. The wind had shifted, so I had a down-wind landing, rolling in. I succeeded in dragging a knee instead of a toe on one side, so I earned a nice strawberry scrape...
<

Is this a great communications medium or what!

So by using the 0.5 G bag string he's got the worst of both worlds. It breaks at the worst possible times and holds like titanium while you're watching the ground rush at you from the side.

Now why didn't I think of that?

Janni,

You need to start listening to people like the FAA, Dr. Hewett, Steve Kroop, Danny, Brian, Paul Tjaden, the late great Rob Kells... They know what they're talking about. Cragin's just a somewhat less obtuse version of Chris. I can't figure out whether he tosses a coin to decide what he's gonna say next or just reflexively states the opposite of any position I present. In either case - this topic is way out of his stickball league.

Note: While the material on ground based towing weak links by Pagen and Bryden which Cragin is referencing is legitimate enough, their discussion of AT weak links is total crap.

You need to figure out who your friends really are - they're not the ones telling you what you wanna hear.

One little gem of accuracy amongst Cragin's latest steaming pile of bullshit...

Yeah, he's totally right about me having gotten totally sick of standing around watching the soaring window evaporate while the one functional tug that has become the Ridgely norm has to deal with a line clotted by endless and needless relaunches on top of mile high tandems grabbing every third slot.

What he's too dumb to get - despite his own experiences - is that by putting the link in the MIDDLE of the range - as opposed to well off the bottom end - you actually improve BOTH efficiency and safety. More airtime, fewer broken downtubes.

>
Come to think of it, I really think that the lighter pilots out there fly with weak links too strong for their total weight.
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I must say - I admire your consistency. None of the other members of the opposition have ever been intellectually honest enough to take that next logical step.

But step back and ask yourself...

Who are the ones breaking the downtubes and skinning the knees? The big dudes or the little chicks?

We've got this great global test population of a decade and a half's worth of aerotowing tens of thousands of pilots ALL of whom have been using the same one size fits all weak link. Are we seeing a trend in which the hobbits are being taken out of the gene pool? Or are we seeing the opposite?

Also ask yourself...

If my motivation in advocating weak link strength 0.6 Gs BELOW the USHPA upper limit is to get people the fuck out of my way at the expense of their safety... How come I'm flying a weak link that holds to a tow line tension of 473 pounds / 1.48 Gs? The guy's an idiot - stay away from him.

David,

I absolutely ADORE complete idiots - the genuine, as opposed to the know-it-all variety. And the less they've towed and learned about towing the better. 'Cause the less they've learned about towing in this hang glider culture the less they've learned WRONG.

Although I'm always happy to see original thinking on any issue... No - you don't wanna be doing that.

You need to understand the point that Danny has so far failed to get across to the bag string crowd.

You can be in a situation in which you are banked on your ear with extremely high tow line tension praying to all the gods you can think of that the weak link holds. I once watched Jonny Thompson interrupt a probable fatal lockout by hitting the gas in a similar situation.

Holly is a near textbook example of what can happen when tension is lost at the worst possible point in a series of oscillations.

Brian,

Thanks much for giving Janni the reality check. It so helps when it's also coming from a source other than me. You got him upset - which means you've got him thinking.

He's a smart guy - he'll get it sooner or later.

[brianvh]

Tad;

what you never get is that insulting someone who's insulted you may gain you creds in a street fight but not in an intellectual discussion. When this whole discussion started many threads ago I felt the same way Cragin did, but since you never insulted me I finally was able to see your side of the argument. Many people who started out with the same belief I did will now never see your side because you get lured into the slap fight. It's hard, but you gotta look past the jabs to gain respect.

If your position is logically correct, people will come around so long as you don't oversell or insult.

You've been overselling by saying weak links CAN'T protect the pilot. They can, though it's not the primary or trustworthy purpose, so it's best not to have them too weak. As for insulting, well...

[RedBaron]

Who are the ones breaking the downtubes and skinning the knees? The big dudes or the little chicks?

The ones with bad landing skills.

[deveil]

alcoholic/addictive types are doomed if they can't resist that first drink. . .
garyD

Tad;
what you never get is that insulting someone who's insulted you may gain you creds in a street fight but not in an intellectual discussion. . . Many people . . .will now never see your side because you get lured into the slap fight. It's hard, but you gotta look past the jabs to gain respect.

If your position is logically correct, people will come around so long as you don't oversell or insult.

But - again - ANYBODY (with half a brain or better) can be an effective volunteer moderator.

NOTHING IS FOOLPROOF!

But you are asking the "moderator", a volunteer, to perform a highly involved and subtle task. However useful and beneficent it may be, it's asking way too much. Sorry to say, you're on your own

the only reason for my writing this post is to back up brian before i totally wash my hands of this. a lot of people, including me, had hoped that the train might stay on the track this time. but i don't know that anyone really believed it would. you've proven them right. don't bother with any apologies, at least not to me, 'cause it won't get you anywhere.

gary devan