simulations

[Tad Eareckson]

Paul,

You're one of the good guys, I've always liked and respected you but...

Am I the only one reading this stuff?

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Greg DeWolf

2000/09/01 09:48:29

>
...(however, I have heard of some complaints of the Bailey's being difficult to work under high loads).
<

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Lauren Tjaden

2008/03/23 22:20:15

>
The barrel release wouldn't work because we had too much pressure on it.
<

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OK, stop me when I've said something wrong or misunderstood something.

It was a tandem flight, the two point Spectra bridle tension was limited by a weak link in the form of a double loop of Greenspot which has consistently broken real close to 200 pounds in a lot of tests I've run.

(Oops - I just realized I did the splits wrong two posts ago. Shoulda read - "...something under a quarter of that." Yeah, that's making more sense to me now.)

That means the secondary bridle tension is limited to half of that - 100 pounds...

unless/until the primary bridle wraps. There should be 200 pound weak link protection in the secondary assembly as well. If not - you're in Holly mode - dependent upon whatever weak link happens to be on the tug end of the system. (And the idiot configurations I've seen on some of those provides no assurances either.)

Lauren, however, was still in two point mode so there was no way her barrels were seeing over 100 hundred pounds, right?

By the way, in accordance with what I've indicated before, if she HAD been using one of my barrels it WOULD have worked and that drill could've turned into the real thing REAL fast - as JD discussed recently in "Weak Links and Tow Bridles". Sometimes two wrongs DO make a right.

According to some tests I've run you need to pull back on the barrel one pound for every 6.2 of loading from the bridle. So Lauren would have needed to be prepared to pull (100/6.2=) about 16 pounds. That ain't real easy under the circumstances and it's already almost two thirds of the 25 pound maximum allowed by USHGA Tow Committee requirements.

If the primary bridle wraps we're talking over 32 pounds of required actuation force and that just flat out flunks.

And as far as I'm concerned - to hell with the Tow Committee regs. If Lauren couldn't budge it in a best of the worst case scenarios - it flunked anyway.

My barrel releases

http://www.flickr.com/photos/aerotowrelease/

have a load to actuation ratio of 20.4 and a much better grip. That means Lauren would have only had to pull five and ten pounds in the best worst and worst worst case scenarios.

With respect to your comments about your experiences with the Baileys and lockouts.

It doesn't take much tension to lock out a glider. All that tension has to do is overpower your control capacity. We all know that you can die with with your 140 pound weak link intact.

You are an extremely competent and highly experienced and accomplished pilot. I don't imagine you get too freaked out by a lockout - especially at altitude - and deal with things calmly long before they've really gone to hell.

Just about all the time barrels are used they're in the company of very experienced AT pilots - that's about all you see launching one point. Whenever an inexperienced pilot uses one it's almost always 'cause a two point bridle wrapped or a primary release failed at wave-off. So these things aren't usually getting much of a workout.

Those aren't good tests of what a release has to be able to do. Kinda like when I drive my car. I'm slow and careful and gentle on the pedals. I've got a lot of deer around but - with respect to the car I've been driving for the past five years - I've never come anywhere near to using my brakes to the limits of what they need to be able to do to certify - a limit that may come in handy some day.

I've got a sister - about Lauren's build. She's also a horse person - used to compete. She was visiting this side of the continent last month.

A week and a half BEFORE Lauren's incident I put one of my barrels on the test rig and cranked it up to 200 pounds. She fired it no problem.

Then I swapped in a Bailey and repeated the experiment. It didn't go nowhere.

I did take over the controls and was able to fire it myself but it was stiff as a board. Do you really wanna be trying to open the pickle jar when you're about to die? Especially when I've provided a cheaper, no downsides option which let's you get to less than a third of that resistance?

The problem with the Bailey is not so much where the weak link or bridle is positioned but that, because of the curve and the wide barrel it makes necessary that the lever is retained by its middle, rather than end, and is not folded back all the way, thus allowing a lot of side loading. Look at the photos in my temp set.

So anyway Paul, had not, by itself, the incident Lauren described more than fulfilled the conditions under which you stated you would switch?

If you do you'll join a small group of converts which includes Sunny, Adam, Ric, PK, John Dullahan, Paul Adamez, Dennis Pagen, John Simon, Hugh, Steve Kinsley. I will be DELIGHTED to help you in any way I can, including comparative demonstrations when I hope to see you in June.

With respect to the other issue...

The bicycle brake lever crap HAS been improved on. As a matter of fact it was improved on long before the Quallaby junk threw the direction of evolution into reverse.

Look at my pictures - temp set. The original Bailey-Moyes AT Release was what we were using in 1991.

Lauren's worried about bashing her face on a basetube mounted brake lever. This thing's just got a wire loop with length of vinyl tubing over it (Lookout). If anything it might make it safer to kiss the basetube (not that that's something that ever seems to happen in tandem ops anyway).

She can't reach a basetube mounted actuator from the top position? Fine. Just do a quick velcro job and swap it to the downtube when you switch modes.

Look at my actuation system:

Primary Release System - Composite Overview

Forget the junk inside the basetube - that's just gravy. Just tie the little string lanyard to the basetube like I did thirteen and a half years ago - long before I figured out how to do the bungee trick. All you gotta do is swat the string. It's always easily accessible by either/both pilot(s) at all times. It can't spin ineffectually around a tube, bottom out, fail in any way, or hurt you. Any two point release could be modified to function like this.

Hell, who am I kidding? Nobody's ever gonna take ME seriously.

So take a look at what Peter Birren's (Linknife) configuration.

http://www.birrendesign.com/LKAero.html

I say mine's the best but you can come REAL close with a huge reduction in cost and complexity.

Don't wanna replace a string each flight and hate me? Look at what Tim Hinkel is doing.

Just about anything is better than the crap we're using now.

Appreciate your comments, Paul. Look forward to hearing from / seeing you.

[Paul Tjaden]

Damn!!!! I knew better than to open my mouth. OK, I knew that you would bring up Lauren's quote regarding not being able to release with the barrel system last week. I am certainly not stupid enough to suggest she was wrong about being able to slide the barrel off of the cam lever but this doesn't change my earlier statement. The pulling force on a barrel system would seem to me to create very little side load. The side load would need to be fairly large to create enough friction to stop someone from easily pulling the barrel off. I have NOT done any serious studies as you obviously have done. However, I HAVE placed a substantial load on a barrel system and it popped off with very little effort. If you can show me that this is incorrect when I get there in June and that reasonably large loads will cause the barrel to jam, I'll switch to your sytsem. Bear in mind that I will only use a pro-tow system so I guess it would just be your barrels. I have great doubts that you can prove this to me but If you can, I will stand by my word.

Regarding the rest of your post about the bicycle brake release, etc. As I said in my original post, I think that some improvements might make the system better such as adding a loop for your wrist, etc. but I really haven't studied that nor do I use this type of release so I'll not make further comments.

See you in June.

Paul

[Tad Eareckson]

Thanks again very much for your comments. It's so refreshing to correspond with someone who's willing to look at evidence and stand by his word despite being a high airtime pilot.

You don't have to respond to or even read most of this but at least skip down to the end and give that a mull.

The terms you cite - easily pull, substantial load, very little effort, jam - are all subjective. Nobody bothers to follow or even read them but there are USHGA Tow Committee quantitative standards for this stuff. There have to be.

They have been modified over time and can and, in fact, must be taken with salt grains but they need to be understood and respected unless reasons to diverge can be justified.

While I'm on the subject... I owe the set published in "Towing Aloft" an apology regarding a statement I made on 2008/02/24. I now realize that they weren't requiring the release to be actuated at 600 pounds - just loaded to that point. That's still a bit stiff - I could live with something along the lines of twice weak link - but not totally unreasonable.

The current AT standards require that a release be operable at twice weak link. One and a half satisfies me. Lauren's failed at under zero and a half.

The barrel is required to blow at a maximum of 25 pounds of actuation force.

For the purposes of our duel I'm guessing your glider is 300. You should be using a weak link which loads your Bailey up to 200. It's gonna take 32 to blow it. That's gonna be 7 over the limit but you're gonna be able to do it and say, "Ha ha, you lose!"

But if you use my barrel you'll be able to pop it at 10 and I'm gonna ask what the Bailey is doing for you that makes it worth the extra 22.

All components of the Bailey - webbing, pin, and barrel - are wide and they're all working against you for no reason. You don't want short and fat - you want long and narrow.

If the Bailey was designed the way it is for a reason then the VG lever on the starboard downtube of my Wills Wing HPAT would be curved.

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Scott Wilkinson

2005/09/22 16:06:24

Our theory is that when she began losing control, she probably whacked at the cable release handle (forgetting---under enormous stress---that it was useless)...and didn't think to reach for the barrel release, because (like many of us) she had almost never used it before.

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Six days ago I came up with a different theory. Anybody wanna hear my theory? Tough shit - here it is anyway.

My theory is that Holly DID reach for the barrel release but since it could have been and probably was loaded to from one and a half to two times what Lauren was seeing - depending upon what Tex had in the way of a weak link at the tug end - that action was about as useful as whacking at the actuator of a primary release with nothing connected to it.

[Tad Eareckson]

Mark,

Sorry, I hadn't realized that the condition that YOUR determination of whether or not a post could be helpful to NEW pilots was grounds for changing the subject line and locking down the topic. I'll have to give the Forum Charter and Rules another skim.

But I really wasn't writing about anything that had to do with pilots or flying flying skill level. I was writing about stuff that an eight year old kid with a Charlie Brown style kite figures out pretty quick without any help or instruction from any hang gliding skygods.

Scenarios 1 and 2... If the kite is low and diving for the ground really fast and you keep holding onto the string it's gonna hit the ground really, really hard.

Scenario 3... If the knot at the bottom end of the bridle comes undone and you keep holding onto the string it's gonna hit the ground really, really, really hard.

Any new pilots having a problem grasping those basic concepts? Skygods?

JD recently started a short lived discussion about the consequences of an out of sequence release combined with a bridle wrap, i.e. - Scenario 3. My stated reaction was something along the lines of "Well duh. What did you think was think was gonna happen when you hung a 75 pound sack of concrete from your nose plate?"

My extended reaction is, "How is it possible that people are even putting gliders on carts without any clue as to what happens when you pull down on the nose of an airplane?"

The subject line I wrote was:

fatality report - simulation

I chose those three words and the order very carefully. In the recent incident which inspired the post the two pilots under that wing - for the purposes of the emergency simulation - managed to kill themselves at least two times over - three if they get lucky. I realize some of my correspondents aren't real fond of arithmetic but that's four to six fatalities. The only reason they're dead only on paper is 'cause this cluster fuck happened way up in the sky - instead shortly off the cart.

A couple of months ago I was wasting my breath warning that the Bailey release was problematic, explaining the science which explained its deficiencies, and posting test results which demonstrated that it didn't come anywhere close to qualifying under USHGA standards.

Some of the counter arguments were:

It's a battle of wits ... and you're out of ammunition.
You are truly a megalomaniac.
He's just an asshole
BWA HAHAHAHAHA

So exactly what does one have to do to get discredited around here?

Oh! I know! Just post the scenarios of what happens when you violate half a dozen towing rules at once and you don't have the luxury of a thousand feet of nice soft air sort things out. THAT gets your topic edited and locked down.

And even disregarding the fact that the post was identified up front as fiction, I don't see how it matters a rat's ass worth whether scenarios are real, postulated, or blended. Anybody who's ever gotten within five tandem flights of soloing behind a Dragonfly should thoroughly understand that those are all very real possibilities.

But, for the record...

Everything in that post mortem was as real as pancreatic cancer.

In the simulation Jim Prahl provided the lockout.

Lockouts at altitude are uncommon and no big deal. Lockouts just off the runway are extremely rare but they happen, they tend to be deadly, and you ALWAYS have to be prepared for them.

The setup was, of course, John Dullahan. It was arguably preventable but both John and the tug driver (Lisa) missed what was going on behind them and I don't think a lot of us can say, while keeping a straight face, that we'd have caught it.

Once the wheels started rolling it appears that John did everything right and on time and the release mechanism was not an issue. But he still ended up with a broken wrist - which was a lot less than observers on the ground thought was gonna happen.

Scenario 1...

Obviously, a straight solo version of Lauren and Dustin without the cushion.

Scenario 2...

Now that the tow community has FINALLY got its collective shit together enough to realize that you MUST have a weak link (or two or three) in the vicinity of the bottom end of the bridle there's a pretty good chance that a bridle wrap is gonna be taken care of automatically. But you can't count on it.

If the wrap occurs without a whole lot of tension or jolt you're still on tow with the lockout getting worse and the Baileys overloaded.

Peter Birren reported two Whitewater (Wisconsin) pilots hospitalized following wrap incidents.

Scenario 3...

I've seen Quallaby releases that could not be made to function - AT ALL. The cable adjustment on these things is critical anyway and the brake lever style can be such that - while fine for the intended destination of curved handlebars - the thing bottoms out on down- and basetubes.

Plan B - Release from the bottom end.

Fine until you get a wrap. If your trim point is far enough aft you just hope that your weak link breaks or tug driver figures out what's going on before you get killed and then start praying that the 250 foot length of Spectra doesn't snag on a fence or Cessna while you're trying to land 'cause there ain't squat else you can do about it at this point.

If your trim point ain't far enough aft the glider's gonna tuck - like it started to do for Jim Prahl before that needless experiment was ended - or tuck and break like it did in the case of a pilot in Romania - I think Rob Kells said it was. That guy was only half killed so I believe it happened nice and high.

I don't know at which is gonna break first in this sort of situation - the weak link or the glider - probably the latter, but I gave things the benefit of the doubt 'cause I already had more than enough energy to kill the pilot.

I believe that the guesstimate on wrap rates is on the order of one in a hundred but the probability goes up with tension.

To summarize - It wasn't a question of which (if any) of those scenarios was the *real* one. There were about eight or nine *REAL* scenarios which went into the compilation. Sometimes altitudes were altered to punish the guilty - sometimes they weren't.

So anyway, Mark, next time you feel the need to edit and lock someone down because you don't think his comments could possibly be useful to new pilots, how 'bout going after something like:

>
It just bothers me when people try to "improve" upon Bobby Bailey's designs ... simply put, the designs are at the maximum of efficiency and safety.
<

My post was thinly disguised fact represented as fiction. The first half of the above statement was astonishing even before the flight report. The second half is complete fiction represented as fact. It is not just unhelpful to new pilots but dangerous to all pilots who base their flying decisions on the unsubstantiated pronouncements of other people - usually based upon their competition standings - which is just about everyone.

By the way... Have you ever preflighted your own tow equipment to see if it's compliant? Or do you just assume that it is 'cause of who sold it to you and/or what everybody's using?

[markc]

So anyway, Mark, next time you feel the need to edit and lock someone down because you don't think
his comments could possibly be useful to new pilots, how 'bout going after something like:
....
....

Hey Tad,

As I mentioned when I locked that earlier thread of yours, you are completely welcome
to open a new one, with a title that accurately reflects its contents.

I know that you have definite opinions about several towing, harness, and release issues.

And I have no problem with any pilot, new or otherwise, being involved in any thread
you might start on those topics.

But believe it or not, there are those out there (including more recent pilots) who have
not been following your many posts for the past year or so. So it would not have been
obvious to any of them what was 'real' in your "fatality report", and what was being
discussed theoretically.

So my modest proposals: Use topics that reflect the actual content of what you want to
discuss; don't use loaded terms like "fatality" just to attract page views.

I truly do not think this is a lot to ask, nor is it a barrier to expression.

MarkC

PS: An example: "Ten towing scenarios drawn from recent events that could have
been disastrous had they occurred at low altitude" .