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Re: Fatal hang gliding accident

Postby Bob Kuczewski » Wed Nov 16, 2011 7:42 pm

Tad,

I'm often not sure about what you're arguing for (or against).

In this case, we seem to have an accident that was caused by an inexperienced pilot most likely cross controlling his glider on one of his early prone experiences (maybe his first prone experience).

Without a 10 page dissertation/dissection, can you agree that's what we're talking about?

Thanks in advance for any brevity you can muster.

Bob Kuczewski
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Re: Fatal hang gliding accident

Postby TadEareckson » Thu Nov 17, 2011 11:40 am

I'm often not sure about what you're arguing for (or against).

1. Sometimes it helps to read the whole post and respond to - or at least think about - some of the questions.

2. Often I'm not arguing - period. Often I'm just having a discussion with, explaining something to, and/or trying to learn something from somebody else. That tends to be more the case on Kite Strings than it is here.

In this case, we seem to have an accident...

Nah. This was NOT an ACCIDENT. This was a CRASH. Accidents in hang gliding are rare to nonexistent. The sport is dangerous enough already without the introduction of accidents to boost our already astronomical incident rate.

...that was caused by an inexperienced pilot most likely cross controlling his glider on one of his early prone experiences...

That was just a symptom/byproduct of a lot of very serious and much deeper issues that hardly anyone is the slightest bit interested in doing anything about.

...maybe his first prone experience...

No.

Without a 10 page dissertation/dissection...

Yeah, let's try to keep everything geared for the least common denominators in these discussions. We certainly don't wanna lose the ADD demographic when we're trying to get our membership numbers up to something significant.

...can you agree that's what we're talking about?

If it makes you happy.

Does that mean we shouldn't also be talking about why:

a) he preflighted, hang checked, and knew he was hooked in for about five minutes prior to launch?

b) he had to be coached by a Hang Two to keep his glider at the front of the ramp so he wouldn't back it up and kill himself the way Chris Thale did at Henson Gap a wee bit under two years ago?

c) he had to be coached by a Hang Two to keep his nose down so he wouldn't scramble his brains the way Danny Jones - the other eyewitness - would at the Packsaddle ramp some months later?

Gil Dodgen - 1995/01

All of this reminds me of a comment Mike Meier made when he was learning to fly sailplanes. He mentioned how easy it was to land a sailplane (with spoilers for glide-path control and wheels), and then said, "If other aircraft were as difficult to land as hang gliders no one would fly them."

d) hang gliding is so rabid about gearing damn near everything in student training - at the expense of safe flying - for a very dangerous landing technique that the vast majority of hang glider pilots should never be in a position to need?

e) we're building an alternate hang gliding organization, trying to flood it with "pilots" and "instructors" from the original incompetent, unaccountable, and deeply and irreversibly corrupt original, and expecting better results?

Thanks in advance for any brevity you can muster.

Yeah, brevity is the name of the game in hang gliding. If people had any interest in competence they'd be flying with the fiberglass crowd after listening to and understanding long winded "explanations" in the classroom.
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Re: Fatal hang gliding accident

Postby ZackC » Sat Nov 19, 2011 6:09 pm

Firstly, sorry for the delay in responding, but thanks to Tad and Bob for your patience in trying to get me to understand this stuff.

ZackC wrote:I'm getting closer.

So much for that! I just confused myself with the attachment point thing so I've had to start over. I think I've done a pretty good job of illustrating that this is not an easy concept for everyone to grasp (although I may be more challenged than most), and I don't think getting it through to students would be all that useful as long as they understand the towline will not impart any control input.

Tad,

TadEareckson wrote:But If he's just being pulled to the left by an electromagnet or towline connected to his Hewett Bridle rather than using muscle the glider will say, "That's odd, gravity seems to have moved to the left and picked up a bit. Better roll accordingly to keep myself perpendicular to it." And the loading on the wings and wires will remained balanced.

The center of gravity of the system has still shifted, has it not? Are you saying that the loading is only balanced because the glider rolls to make it balanced? And why does the glider feel the need to roll to stay perpendicular to gravity? Most gliders have pretty neutral roll stability. When you put them in a bank they'll stay at that bank despite the fact that gravity has moved. I can understand what you're saying with regard to pitch, as gliders have positive pitch stability. At any rate, if the glider says 'gravity has shifted' when a rope pulls the pilot, what does it say when the pilot pushes/pulls on the control frame? I intuitively know the situations are different but I'm having a hard time explaining why.

TadEareckson wrote:What would you predict the plane would do in each of the four scenarios?

Roll left, roll right, pitch down, pitch up. I believe that in the roll cases as long as the passengers stay at the wingtip the plane will, in theory, continue to roll up to a maximum bank of 90 degrees depending on the plane's roll stability (although in practice it would end up in a steep dive long before that), while in the pitch cases it would settle on a new angle of attack fairly quickly and stay there (assuming it doesn't stall). But we're talking about 100% weight shift, which is as I previously said how I thought pitch control was effected. Where does differential wire tension come in for pitch? If the nose/tail wires are just there to keep the control frame from collapsing, I don't see why the tension on them would be significant.

TadEareckson wrote:The control frame is a CONTROL frame - not a tow hook. If you tie a rope to the steering wheel or handlebars you're asking for trouble.

How about attaching the tow rope solely to the keel at the hang point, then? It's pulling on the same part of the glider as when attached to the pilot. Is the only advantage of towing from the pilot over this configuration the fact that his weight shifts will be more effective with his increased effective weight?

Prior to this discussion my understanding of hang glider control was the airplane scenario you described, although I knew roll involved more without really understanding it. I also knew that a tow rope pulling a pilot didn't cause a weight shift but didn't understand why. I now have a better idea of how roll works. My understanding of pitch has not changed. I'm still fuzzy on the rope/magnet thing.

TadEareckson wrote:What's the point in training anyone to fly from the downtubes?

Because we execute the most dangerous portions of flight from the downtubes.

TadEareckson wrote:I never had a problem with a student transitioning TO prone.

Transitioning early off launch can be very hazerdous. I wasn't there but that may have been the cause of Danny Jones's crash. It's difficult to transition while flying with any speed. If I need to turn immediately off launch (e.g., ridge soaring in light wind), I'll stay upright until I'm established on the ridge

Bob,

bobk wrote:With regard to the physics of the camera mounting, I think I can help you with a diagram or two.

Appreciate it. My confusion came from erroneously thinking that the component of the force (camera weight) tangential to the center of rotation was greater for the nose than basetube case. I now understand that all that matters is the displacement of the point of application of the force from the center of rotation (and the force itself).

bobk wrote:I think Tad will agree with that approach - although I'm not sure he'll ever agree that he's ever just plain wrong.

Tad is willing to admit he is wrong and in fact wants people to find holes in what he's saying as that's how knowledge is advanced.
http://kitestrings.prophpbb.com/topic6-30.html#p161

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Re: Fatal hang gliding accident

Postby Bill Cummings » Sat Nov 19, 2011 8:05 pm

Zack,
"Tad,---
Like the 2500 pound jobs I dropped in the mail for Zack on Saturday?

Unless Tad has told you he has already done this test, put your tow bridle between to vehicles with the weaklink that you will be using and break the weaklink. Make sure there is not enough stretch in the bridle to snap back any hardware in your eye.
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Re: Fatal hang gliding accident

Postby Bob Kuczewski » Sat Nov 19, 2011 9:02 pm

billcummings wrote:Make sure there is not enough stretch in the bridle to snap back any hardware in your eye.

I was very lucky to meet Michael Robertson (inventor of Robertson's Charts of Reliability) earlier this year. He's not shy about telling people that he has one glass eye from a tow ring that snapped back during a boat towing incident.

So Bill's advice is very important ... and it wouldn't hurt to add proper eye protection as well.
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Re: Fatal hang gliding accident

Postby ZackC » Sun Nov 20, 2011 7:51 am

Thanks for the advice. Can't hurt to try it but I'm not too concerned about bridle stretch...Tad is really anal about this stuff. The bridle is made from AmSteel Blue, which is Dyneema, which is a low-stretch material very similar to the Spectra usually used for bridles.

About Michael Robertson, Tad said this of his incident on this forum:
TadEareckson wrote:Mike Robertson was on the back of the boat which was towing someone using some piece o' shitt weak link that wasn't up to the job and UNDOUBTEDLY using polypro for the towline....This is why people who know what the hell their doing use towline and bridles which don't stretch and weak links which don't blow.

Don't know his source on the line material but I do know he attended a clinic with Michael (mentioned earlier in this thread).

But yes, I always fly with eye protection.

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Re: Fatal hang gliding accident

Postby Bob Kuczewski » Sun Nov 20, 2011 9:07 am

ZackC wrote:I'm not too concerned about bridle stretch ... Tad is really anal about this stuff. The bridle is made from AmSteel Blue, which is Dyneema, which is a low-stretch material very similar to the Spectra usually used for bridles.

This points out why I struggle with Tad. He really has a lot of good knowledge about this sport, and he's a potentially fantastic asset to any organization. But when he's on the wrong side of an issue he becomes worse than useless because he's so convinced that he's right. I believe this is compounded by self-esteem issues with regard to people who he feels have disrespected him. So I don't really know how to handle the situation.

The goal of the US Hawks is to actually build an alternate national hang gliding organization. I think many of us agree that USHPA has gone astray, and the only fix I can see is to give them some competition. But for all that Tad brings to this new organization, he's mostly been keeping us from moving forward through his endless filibustering. So I'm considering changing the posting rights on the "Building the US Hawks" forum to include people who've made a commitment to helping us actually build that new organization. At this time, that would not include Tad. I'd be interested in what you or anyone else thinks of that plan.

Thanks.
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Re: Fatal hang gliding accident

Postby TadEareckson » Mon Nov 21, 2011 9:09 am

...although I may be more challenged than most...

Nah. You're in the top tenth of a percent. If you represented just average challenged then hang gliding would have no problems beyond the immutable physics of the environment.

...and I don't think getting it through to students would be all that useful as long as they understand the towline will not impart any control input.

Yeah, that's good enough to make someone a safe, competent flyer. But a real PILOT should understand the physics of what's going on. And the more real pilots we have in the population the fewer opinions we're gonna hear. And the easier it will be to disembowel morons who have them.

The center of gravity of the system has still shifted, has it not?

Yes and no. It's shifted in space but the glider doesn't really understand that because it can't see the horizon and is only reacting to what it feels. (Kinda like if one of us humans flies a Cessna into a cloud bank he's screwed without an artificial horizon.)

Are you saying that the loading is only balanced because the glider rolls to make it balanced?

Yeah. But think of it as one of those Einsteinian thought experiments Brian Greene illustrates on Nova. Leave the glider alone, instantly shift the Earth and increase its mass.

And why does the glider feel the need to roll to stay perpendicular to gravity?

It doesn't know it's rolling. It thinks it's remaining level.

Most gliders have pretty neutral roll stability. When you put them in a bank they'll stay at that bank despite the fact that gravity has moved.

It stays in the bank BECAUSE OF the fact that gravity has moved. When you use muscle to initiate and coordinate the turn you're thrown to the outside of the curve by centrifugal force (the glider wants to turn, Sir Isaac says you're trying to keep going straight (which you will start doing again if your carabiner fails)). Centrifugal force is measured in Gs. G is short for Gravity. The glider can't tell the difference between you pulling yours and Earth pulling its.

I can understand what you're saying with regard to pitch, as gliders have positive pitch stability.

We're not concerned about stability here - just how the glider initially responds. If you keep pulling from the front then the glider will trim to a stable pitch attitude and climb. If you keep pulling from the side you'll soon find yourself in a lockout. But forget those - just think about the glider's initial reaction.

At any rate, if the glider says 'gravity has shifted' when a rope pulls the pilot, what does it say when the pilot pushes/pulls on the control frame?

When the pilot pushes/pulls on the control frame there MUST/WILL be differential wire tension. Points on the glider - nose, tail, left and right wings - WILL be unequally loaded and the glider will know its center of gravity is no longer balanced and will react accordingly.

Roll left, roll right, pitch down, pitch up.

Yes.

I believe that in the roll cases as long as the passengers stay at the wingtip...

Again, don't worry about what happens as things progress, just the initial response. That's all we need for the purposes of the exercise (and I'll probably find myself out of my depth if we take things too far).

But we're talking about 100% weight shift, which is as I previously said how I thought pitch control was effected.

Yes. And roll control is basically/partially effected the same way.

Where does differential wire tension come in for pitch?

The same thing. Look what happens with your nose wires when you push out - or tail wires when you pull in.

If the nose/tail wires are just there to keep the control frame from collapsing, I don't see why the tension on them would be significant.

They do most of their work keeping the control frame from collapsing when you're pushing out and pulling in.

How about attaching the tow rope solely to the keel at the hang point, then?

We had a discussion with Mike about that on Kite Strings. That was an idea Bart Doets had - and somebody else experimented with - before people figured out you needed to route half or more of the tension through the pilot.

Mike Lake - 2011/03/08

Glider scrap.
Poor fellow, a vegetable for a while then spent the rest of his life as someone else.

One of several really good reasons why I don't fly with "backup" releases.

It's pulling on the same part of the glider as when attached to the pilot. Is the only advantage of towing from the pilot over this configuration the fact that his weight shifts will be more effective with his increased effective weight?

Mike Lake - 2011/03/08

Pulling from nothing but the hang point, by this I mean a SINGLE line at just the heart bolt area is fine and offers the same roll stability (or a reduction in instability) as other configurations.
The trouble is a small surge can (and does) rotate the glider around the pilot. It's easy to visualise how this would happen.
On my early two point designs I always considered the bottom line to be there just to stop the glider tucking.

No.

I'm still fuzzy on the rope/magnet thing.

To make things easier and cheaper... Lose the flying wing passenger plane and truck tow a sailplane - using the surface tow point under the CG - out on the salt flats. The sailplane reacts to the rope the same way a hang glider does. Gas the truck and the sailplane pitches up. Swerve to the left and the sailplane rolls to the right.

Or, hell, just run around on a soccer field with a kid's kite.

Because we execute the most dangerous portions of flight from the downtubes.

1. When flying from the slopes on one of those portions we fly from the downtubes by necessity, the other we nearly always fly by choice - often a really poor one.

2. I'm not remembering any of the hundreds of "students" I launched off the dunes having down versus base tube specific problems.

Transitioning early off launch can be very hazardous.

Any time anyone takes a hand off the control frame CAN - depending on the circumstances - be very hazardous. This is a point that folk like Donnell, Peter, and purveyors and users of the Wallaby Release address through massive denial.

I wasn't there but that may have been the cause of Danny Jones's crash.

I dunno. Conditions were nasty, I'm having a hard time visualizing someone fighting a roll with his hands on the downtubes and letting go of a lot of pressure at a critical moment without a lot of incentive do do so, and I've never before heard of something like this precipitating an incident. It's kinda like taking your hand off to blow the first stage on your Koch release - it's not time critical, you can do it pretty much at your convenience when everything is reasonable.

It's difficult to transition while flying with any speed.

Which is why I think it's a really good idea to stay on the basetube until the glider trims out in ground effect.

If I need to turn immediately off launch (e.g., ridge soaring in light wind), I'll stay upright until I'm established on the ridge.

I wish everyone had learned soaring on the dunes. One tends to lose a lot of inhibitions when several inches become critical.

Tad is willing to admit he is wrong and in fact wants people to find holes in what he's saying as that's how knowledge is advanced.
http://kitestrings.prophpbb.com/topic6-30.html#p161

Somewhat unfortunate example. I DID admit being wrong - the problem is that I WASN'T. We subsequently figured out that what was going on WAS consistent with the vector diagrams.

Much better example was when we were dissecting adverse yaw and you fixed my thinking about sweep being analogous to a rudder instead of a vertical stabilizer.

http://kitestrings.prophpbb.com/post31.html#p31

I'd had that stuck in my head wrong for decades.
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Re: Fatal hang gliding accident

Postby Bob Kuczewski » Mon Nov 21, 2011 12:58 pm

TadEareckson wrote:I'd had that stuck in my head wrong for decades.

So how many innocent people got "disemboweled" over that little mistake?
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Re: Fatal hang gliding accident

Postby TadEareckson » Mon Nov 21, 2011 1:38 pm

Make sure there is not enough stretch in the bridle to snap back any hardware in your eye.

Did you also wanna take this opportunity to say anything to Peter about his recommendation of perlon as a no-stretch material appropriate for bridle construction?

I was very lucky to meet Michael Robertson...

I've had mixed results with my associations with Mike over the years.

The first came about in 1982 as a consequence of his running of my first instructor certification clinic - along with Matt Taber, Richard Hayes, a couple of other Kitty Hawk Kites people, and a couple of miscellaneous - fourteen months after the initiation of the "just prior to launch" hook-in check requirement and that issue was never touched on. We at Kitty Hawk continued teaching untold hundreds of "students" - fortunately the overwhelming majority of them one-timers - to do hang checks and assume that they were hooked in.

I myself had started lifting and tugging and skipping hang checks in 1980 but didn't advertise it 'cause I still thought of it as a cheat, a dirty guilty secret, a manifestation of my innate laziness. The hang check was then and remains today something sacred in our idiot religion.

Sixteen years later Mike crashed me twice on tow - once by dumping tension on me when I was straight, level, and waiting to go up and once by flooring it after I came off the cart in a crosswind induced roll.

Don't know his source on the line material...

1. He's got a glass eye so we know it wasn't spectra.

2. Polypro floats.

3. Has anybody ever heard Mike speaking out on the issues of elastic tow materials and/or understrength weak links?

P.S. I was a major boomerang freak prior to and overlapping a lot of my hang gliding career. In January of 1978 two of us threw at the same time. The bozo to my right didn't move into position to catch his and I thus ASSUMED that his was where he was and focused on catching mine. My right pupil has been dilated ever since.

If I'd been wearing sunglasses I'd have been OK.

But when he's on the wrong side of an issue he becomes worse than useless because he's so convinced that he's right.

I'm not so sure that you have a solid consensus - even here - that I'm on the wrong side of any issues.

I believe this is compounded by self-esteem issues with regard to people who he feels have disrespected him.

Any trace of self-esteem I ever had was ground to dust by the age of about seven or eight. So I don't worry about it anymore. I instead focus on knowing what the hell I'm talking about.

So I don't really know how to handle the situation.

Try focusing on knowing what the hell you're talking about. When everybody gets on the same page with two plus two equals four the need for amateur head shrinkers greatly diminishes (from below zero to WAY below zero).

The goal of the US Hawks is to actually build an alternate national hang gliding organization.

Yeah. An even shoddier version of USHGA.

...and the only fix I can see is to give them some competition.

Mark G. Forbes - 2011/09/29

It's not just concern for meet directors and policy makers...it's about our continued existence as an association. It's about minimizing the chance of our getting sued out of existence. We're one lawsuit away from that, all the time, and we think hard about it.

Or we could just wipe them off the map the way they've very long deserved to be.

But for all that Tad brings to this new organization, he's mostly been keeping us from moving forward through his endless filibustering.

filibuster: an action such as a prolonged speech that obstructs progress in a legislative assembly while not technically contravening the required procedures.

I'm not really seeing how I filibustering. I'm posting stuff on a forum that nobody has to read. How is that stopping anybody from doing anything?

So I'm considering changing the posting rights on the "Building the US Hawks" forum to include people who've made a commitment to helping us actually build that new organization.

Yes, good decent people who have no clue what they're talking about, are GENUINELY interested in making this a safe, competent, better sport, hate Tad's guts, and will go along with whatever Bob says.

At this time, that would not include Tad.

The new GT aerotow release, new as of July 11th 2009, is designed to be used with a V bridle and a 130-pound green stripe Dacron tournament fishing line weak link. At this time it is not recommended to use this release with a higher value weak link.

But once Bob gets everything firmly entrenched just the way he wants it with his handpicked team of dedicated hang checkers I have NO DOUBT WHATSOEVER that Tad will be welcomed back with open arms!

Tired of seeing an inflammatory topic on the front page? Click on the "BURY this topic" link at the top of the page. Once a topic gets enough votes, it will be moved to "The Basement" forum where it will no longer show up on the front page.

I'd be interested in what you or anyone else thinks of that plan.

PM me if you really want to make a statement.

(EDIT: all the PM's so far have been very supportive and positive, thanks guys! )

THE END

I worry every time I see my PM notification, and then after I read it, just more and MORE support from everyone thanking me for getting rid of these people.

This community rules and is 100X better without them. THANK YOU ALL for your support. I really appreciate the flood of positive PM's. I expected only the people with an issue to PM and flame me. What a surprise when 100% of the PM's were positive instead

Another morning... another basket of support PM's
Thank you, thank you thank all!

-

"To be what you've never been you must do what you've never done." - Unknown

You REALLY wanna know what I think of that plan? Temporarily remove the FCC restrictions.

So how many innocent people got "disemboweled" over that little mistake?

Zero. It's aviation theory. And hang gliding people don't do theory and aren't affected by physics - just the opinions of professional pilots with huge track records.

So what's your point?
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