Weak links

[Tad Eareckson]

http://www.hanggliding.org/viewtopic.php?t=24305
Reflex bridles at work

Tom Low (Cloudhopper) - 2011/12/25 18:22:41 UTC
Belmont, California

In the video description, the poster explains that the bridle failed when he "tried to transition" what do you think he means by "transition"? From tow to free flight?

No no no no. I assure you that the ABSOLUTE LAST THING he was trying to do was transition to free flight. Free flight actually isn't all that hang glider pilots always crack it up to be in all circumstances.

Flyingseb - 2011/12/25 20:49:45 UTC
Brittany



very close call!

I found the early stage of his towed flight very steep.

Ya think?

Would it be possible that he'd break the weak link, luckily with enough height to recover?

That's how aerotowing works pretty much all the time. It's likely that you'll break the Davis/Rooney Link every launch, luckily with enough height to recover.

Avolare - 2011/12/26 03:34:51 UTC
North Carolina

Probably an upper / lower tow bridle. For launching from a dolly (ground based towing) I think it's better to have the tow line split above and below the base bar.

The problem with that is once you're a couple hundred up, the upper bridle inhibits climbing. So you need two releases, upper and lower. We used to do this boat towing.

One release, two stages.

Then again, maybe he just couldn't release?

- DID YOU *READ* HIS ACCOUNT? Did he report being unable to release? When he wanted to release the first stage he released the first stage. And - as you should well know (assuming you were using Koch two stages (which you probably were)) - it's easier to blow tow than it is to blow just the first stage.

- WHY THE FREAKING HELL DO YOU THINK HE'D HAVE *WANTED* TO RELEASE?!?!?!?!?!

Jason Rogers - 2011/12/26 10:38:12 UTC

I saw one break as bad as that about 100 feet up. The glider did exactly that whipstall (GTR175), fell like a stone and pulled out of the dive with the basebar going through the grass. Pilot had a little sit down before launching again.

That was in the day when we had to remember stuff rather than videoing everything that happens.

So? You think any of these assholes are capable of learning anything from ANYTHING depicting reality?

Mike Bomstad - 2011/12/26 20:31:18 UTC

Well I figured it out, they used split bridle but attached both to the shoulder points rather then the waist........OMFG!!!!

YOU figured something out?! OMFG!!!!!

When he released the first one (Over the bar) that leaves the other under the bar ( pulling you down @ your shoulder.... ie pulling you aft, gliders nose goes up.

Right Mike!!! The tow angle changes RADICALLY when you blow the first stage because instead of the tension going to the release mounted on your chest the tension is now going to the release mounted on your chest. And all this time I've been assuming that you're a total idiot.

No way to pull in from that.

Yeah. NO POSSIBLE WAY.

Surface tows require you to be attached at the waist area. NEVER @ the shoulder.

Yeah. Make sure you phone Europe ASAP and tell them to immediately ground all these things everybody and his dog has been using for the past quarter century.

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Can somebody who hasn't been kicked off of this shithead asylum yet tell me if whatever I'm not allowed to see is as moronic as what I'm allowed to read?
---
2013/02/28

Here it is:

[Tad Eareckson]

http://www.youtube.com/watch?v=UMsIkAOeJ0I

jwm239 - 2011/12/24

...whoa...looked like a very high AOA on tow...

No. Very low ANGLE OF ATTACK - 'cause he's UNDOUBTEDLY stuffing the bar, very high PITCH ATTITUDE 'cause his driver's going like a bat outta hell.

plus a too-fast (?) tow speed...

Do ya think?

...plus a rising air bubble (?)

Yeah. A huge glassy smooth thermal rising right off beach the just as he came off the cart. This just wasn't his day.

...adding up....whoa....promptly used superior skill to escape unscathed.

Yeah. Astonishing. He gets a death grip on the basetube while being tossed around like a rag doll while everything's in free-fall mode then holds the bar back as far as human anatomy will allow. Totally righteous stuff, dude.

Danair02 - 2011/12/24

You should by all rights be dead; the only reason you're alive is blind dumb luck and luff lines! In 35 years in this sport I've seen some crazy acts but this takes the cake.

Yeah, this guy sure seems like a real asshole to me. He takes a flying vacation, pays somebody to set him up with safe equipment and give him a safe tow, gets dangerous equipment and a dangerous driver, reacts as best as anyone would be capable, and gets down in one unscathed piece. He should probably have his rating revoked.

You want crazy acts for taking cakes?

http://www.ushawks.org/forum/viewtopic.php?f=2&t=802
AL's Second flight at Packsaddle how it went

Rick Masters - 2011/10/19 22:47:17 UTC

At that moment, I would banish all concern about launching unhooked. I had taken care of it. It was done. It was out of my mind.

Gordon Rigg - 2011/12/24

...and don't ever think you are too low to use a parachute...

Bullshit.

If you have an intact glider you're damn near ALWAYS too low to use a parachute - especially within drifting range of power lines or water - not to mention water that moves.

- if you might need it get it out and think about it later.

Yeah. Just throw it whenever. Who's to say when you might get clipped by an A-10 on a training exercise or tumbled by an invisible dust devil or shear layer? Better just get it out and be safe rather than take a chance at being sorry.

I pulled mine at 400 feet and it worked fine!

Well that's just GREAT!!!

- But you did it AFTER the midair or failed, deliberate, low level aerobatic maneuver, right?

- He wasn't AT four hundred feet.

- Regardless of the altitude in a situation like that the parachute would've been the wrong or a useless call. In his particular situation, for example, he's got a shot at flying his way out of it. He goes for the chute he has to let go of the basetube with one hand and risk falling into the sail and there's no guarantee that he gets to the handle in time or gets the deployment bag into clear air or that the chute opens if he does.

- Even if someone had a one hundred percent reliable chute which had no chance of fouling with the glider he wouldn't use it. The instinct will be one hundred percent geared to flying the glider - and that's the right instinct.

Did you wanna say anything about preventing an insanely dangerous situation like that in the first place by not using a bridle which just blows apart? Just kidding.

fatboycrash - 2011/12/24

So, what did you learn from this?

Little to nothing from reading the comments on the YouTube posting and on the Jack and Davis Shows (save for Ridgerodent's) - I hope.

[Zack C]

Can somebody who hasn't been kicked off of this shithead asylum yet tell me if whatever I'm not allowed to see is as moronic as what I'm allowed to read?

It's just a still frame extracted from the video...about 4 seconds in.

The thread Tad is referencing is here by the way:
http://www.hanggliding.org/viewtopic.php?t=24305
Reflex bridles at work

Make sure you phone Europe ASAP and tell them to immediately ground all these things everybody and his dog has been using for the past quarter century.

Don't they normally attach two stage releases at the waist? I don't know what impact moving one to the shoulders would have...seems to me like it would just cause the pilot to rotate head down a bit.

Right Mike!!! The tow angle changes RADICALLY when you blow the first stage because instead of the tension going to the release mounted on your chest the tension is now going to the release mounted on your chest.

Perhaps he meant that when the first stage was released the glider's nose was no longer being held down by the tow rope going over the bar, causing the nose to pitch up.

By the way, weak links have cropped up here as well:
http://www.hanggliding.org/viewtopic.php?p=264182

Zack

[Tad Eareckson]

Looks like I have some work cut out for me, courtesy the Jack and Davis Shows, but lemme do something quickly for the moment.

Perhaps he meant that when the first stage was released the glider's nose was no longer being held down by the tow rope going over the bar, causing the nose to pitch up.

No, that's very likely a big factor in what's going on with that whipstall but that's NOT what this idiot means. (We really need to do some work on this nasty "giving people the benefit of the doubt" defect in your personality.)

THIS:

When he released the first one (Over the bar) that leaves the other under the bar ( pulling you down @ your shoulder... ie pulling you aft

is what this asshole means.

Now, assuming there were any truth to that insanity...

How would the glider respond if the towline were pulling the pilot aft? (Do try to recall our little discussion about the chain mail and electromagnet and differential wire tension. Or, hell, just watch what the glider does in the video when the towline's pulling the pilot hard straight forward as he's coming off the launch cart and not doing much with his hands and think about the converse.) If you have that concept down you can absolutely decapitate this stupid sonuvabitch.

[Steve Davy]

Or, hell, just watch what the glider does in the video when the towline's pulling the pilot hard straight forward as he's coming off the launch cart and not doing much with his hands and think about the converse.

A real "lightbulb" moment for me! Thanks Tad.

[Tad Eareckson]

Thank you Santa, everything fresh on the screen was REALLY worth waiting a few extra days for.

Lightbulb...

Donnell partially understood this with respect to pitch but...

Donnell Hewett - 1982/09

In addition to the above mentioned roll and yaw tendancies, there is some sideways force on the pilot due to the body line. This is illustrated below:



As can be seen, this sideways force tends to pull the pilot over to the correct side to make the glider turn naturally in the proper direction.

...NEVER understood that the same thing also applies with respect to roll. And nobody who still uses that lunatic two to one bridle ("flappy string V kludge") does either.

And if anybody wants to kick Wonder Boy while he's down and twist the blade while he's bleeding - as he very richly deserves - ask him how he thinks the glider will respond if the pilot maintains his grip on the basetube while the towline is pulling him back with respect to the glider.

Do try to get your shots in quickly, I'm sensing a Davis Show lock button finger starting to twitch.

[Tad Eareckson]

Oops.

Tad Eareckson - 2011/12/27 04:26:49 UTC

Very low ANGLE OF ATTACK - 'cause he's UNDOUBTEDLY stuffing the bar...

...reacts as best as anyone would be capable...

Another major pooch screw because of reliance on:
- memory instead of doing the ACTUAL CHECK "just prior to" typing
- accounts without proper analysis of the ACTUAL DATA, reading between the lines, and noting what ISN'T being said

What's he flying? A Wills Wing Eagle? Probably not yet God's gift to aviation.

Everything important under the glider is clearly visible until 0:14 - the point at which things start really seriously going to hell.

He's UNDOUBTEDLY *NOT* stuffing the bar. He's not pulling in at all. And he REALLY SHOULD BE 'cause he could at any moment really need something a lot better than normal angle of attack. And my feelings toward the driver have softened a good bit.

The moment the real footage starts rolling - at half past 0:05 - we can confirm that he's using a chest mounted two stage release by looking at the over/under bridle.

And let's not call that thing a "bridle" - 'cause it ain't. Let's call it an over/under or split towline.

At around 0:06 he's pulling the dolly - which looks like a welded steel T job - into the air in something of a left roll, probably because of the slope of the beach.

At 0:07 he takes a pretty good yaw to the left as well, maybe because of the roll, maybe because of an on-shore breeze, maybe both.

Through 0:08 he's level and lifts the cart, a lot more than is necessary, then separates. Takeoff speed a bit excessive.

At 0:09 he's already in deep shit if he loses the towline 'cause he's let the bar go where it wants. At this point this is a Dragonfly aerotow and the first thing we do after getting off the ground is pull in substantially to stay low until the tug gets off the ground. He can do the same but doesn't.

And on up to 0:14 he doesn't pull in and his driver doesn't ease up on the gas. Nobody gets high marks here.

I think he's climbing so steeply and fast that he's got a lot of upper towline leg pull down/back on the basetube when he goes to blow it and the abrupt loss of that force is what precipitates the pitch-up to near vertical at that mark.

There's no excuse to be using a split towline - or weak link (mine would be seven hundred pounds) - that would blow in those circumstances, but there would be a pretty good jolt after he blew the first stage. So if it was gonna blow on a tow that would've been the one to do it.

The glider continues to climb near vertically for a pretty good two seconds and when he reappears at 0:16 he still doesn't have the bar even back - let alone stuffed.

Think I need to give Danair02 half an apology (even though I still don't think he knew what he was talking about 'cause he failed to give any constructive criticism whatsoever.)

prithg76 - 2011/12/18

This whip stall ocurred...

Sounds a bit passive.

...on the beaches of Mexico...

Well, we don't seem to be trying to steer a lot of business to this wonderful operation.

...a few years back.

So how come we're just hearing about it NOW?

This was the first flight of my trip which turned into an eye opening moment.

And maybe there were one or two things you did better on the second flight of your trip that had needed work on the first flight of your trip?

Many mistakes were made on launch...

Really? By whom? Besides the guy behind the camera there only appeared to be one person at launch and almost definitely only one person on launch who had any bearing on anything relevant to the events which unfolded.

Maybe there was an observer on a radio transmitting, "Faster! Faster! FASTER!!!" If so, how come you're not telling us?

...but the extreme tension...

Yeah. EXTREME tension. Very much like...

http://groups.yahoo.com/group/skysailingtowing/message/6726
Weaklinks

Peter Birren - 2008/10/27 23:41:49 UTC

VERY high towline forces and ... still the weaklink doesn't break (.8G).

...Peter's VERY high towline forces. Even when the weak link is limiting the tension to forty percent of what's allowable in REAL aviation. If the glider's standing on its tail the forces must be astronomical.

...from the tow (done by truck) was enough to rocket me into the air.

And there was nothing you could've done to mitigate that situation?

After the disorienting whip stall...

Translation:

I had no clue which way was up or what to do to keep it there until after being flung around like a rag doll for a while.

I managed to get the glider level and land. Phew! Close one.

And there was ABSOLUTELY NOTHING you could've done better on that one to have made it less of an eye opening experience?

Operator error on BOTH ends of the line plus equipment failure on the downwind end. You got killed but good on that one and you haven't done a whole lot to make sure it doesn't happen to somebody else.

[Zack C]

How would the glider respond if the towline were pulling the pilot aft?

It would pitch down. I thought about that, and the magnet thing, when I read his post, but I didn't think I understood him as I have no idea why pulling from the shoulders would pull the pilot aft.

He's UNDOUBTEDLY *NOT* stuffing the bar.

Yeah, you really lost me when you said he was.

Don't they normally attach two stage releases at the waist?

I said that because I remembered Gregg configured his this way, but then I watched a vid I made of someone from the UK foot launching with a Koch (password = 'red'):
http://vimeo.com/17743952

http://farm1.staticflickr.com/435/19224482318_2da3f48afe_o.png

The release is clearly at his shoulders, consistent with what Mike Lake said. However, Gregg and Mike B's vids show it can be done from the waist, so it doesn't appear to be that critical.

Zack

[MikeLake]

... However, Gregg and Mike B's vids show it can be done from the waist, so it doesn't appear to be that critical.

Actually Zack it does make a difference as can clearly be seen from Mike B's video.
The top line is in contact with the base bar almost from the off and it is straining against it right up to first release. Making the attachment point higher up the body gives the pilot a bit of extra leisure time before the first stage release and there is no need for the line to ever contact the bar.
Of course the hip configuration works, right up to the day the top line decides to get the wrong side of your wheels or instrument mount.

[MikeLake]

http://www.youtube.com/watch?v=XA9Lcju5GZw