4strings release

[deltaman]

Hi Tad,
I tested the 4strings on my own in real..
When I did the head signal to GO I armed the release unintentionally and went like this.
I felt absolutely nothing in my teeth.
That would be perfect if I didn't discover that probably all my AT was less than 27.2kg tow line tension including when the cart starts to roll ! Friends already told me they couldn't release in a normal tow when they tested it before me.
I know this release is for "high" load emergency use (>27.2kg) but sometimes we need to release on the cart before it gets worse and here I'm not convinced at all that it is possible in time..
Is it a way to build same kind of release with less direct force needed, and still nothing in your teeth ? (lanyard OD ? 3 strings ?..)

for a better look, don't forget HD setting:
http://www.youtube.com/watch?v=RiqhAQ1dn2M

[Tad Eareckson]

Wow. That's extremely disturbing/embarrassing.

Based upon the measurements I got I was pretty sure I was good to go by a factor of two.

If the release won't function at and well below normal tow tension it's not a whole lot more useful than the barrel release on the other side because - as all of us who haven't had our brains totally rotted out by Dennis Pagen and the aerotowing industry well know - it takes very little misaligned tension to lock us out and kill us.

I did some testing with a three-string version but decided that the four-string was the better way to go and Steve Kinsley pretty much independently reached the same conclusion but this is definitely not acceptable.

I really loved the four-string because of its elegance and load capacity but this makes it pretty obvious that it needs to be a three-string. A three-string will drop the minimum required load WAY down and shouldn't present much of a problem on the high end but - of course - it needs to be tested at or above full weak link.

The four-string can be used as a three-string just by leaving one of the loops out of the hookup and securing it out of the way and I'd recommend doing that and running a couple of tests behind the tug.

The remote barrel isn't as elegant - you can't just release the line from your teeth to blow - but it sure kicks the multi-string's ass in terms of low tension performance.

Really sorry about this setback but what we're doing sure beats the hell out of flying bent pin Baileys for decades, ignoring the failures and fatalities, and endorsing them because of their huge track records.

[deltaman]

Do you still have the necessary to measure the L/A ratio of the 3strings setting ?
If yes, please..

[Tad Eareckson]

Quick answer...

I just dug a new 205 leechline Four-String up from downstairs, hooked it together as a Three-String, and pulled it open by hand.

The resistance was negligible.

An issue you/we may be having with the Four-String...

The loops will develop a set/memory/fold as they're flown/used - especially the loop engaging the Bridle Link (under the most load). This set WILL increase the required minimum actuation tension to some extent.

Another suggestion...

Nobody - 2012/11/14 19:49:37 UTC

Just install a weak link on the other side of the bridle. That will double the load on the four string. Problem solved.

That was WAY too good to waste on a Private Message.

P.S. A goddam Cooper's Hawk just bounced off the window taking a shot at my little parrot. Scared the crap out of both of us - my heart's still pounding.

[deltaman]

Another suggestion...

Nobody - 2012/11/14 19:49:37 UTC

Just install a weak link on the other side of the bridle. That will double the load on the four string. Problem solved.

That was WAY too good to waste on a Private Message.

With "bridle", he means tow line ?.. Sorry I'm not sure to imagine the right setup ?..

[Tad Eareckson]

It's a joke.

The total morons at the Florida flight parks are telling their totally moronic students that putting loops of 130 pound Greenspot on BOTH ends of the one point bridle will double the towline tension required to blow tow. And their totally moronic students are BELIEVING them.

The Jack Show discussion is here:

http://www.hanggliding.org/viewtopic.php?t=27393
Pro towing: 1 barrel release + weak link or 2 barrel release

and the hatchet job on it starts here:

http://www.kitestrings.org/post3093.html#p3093

[deltaman]

We will have another problem with the 3strings when used armed:
each time your head becomes closer to the clamcleat, the lanyard rather than be slack (as you can see in my video) will reduce its length and you won't be able to recover it.

[Tad Eareckson]

Multi-String history review...

Steve Kinsley originally used a Multi-String that was configured like this:

http://www.flickr.com/photos/aerotowrelease/8316097916/
http://www.flickr.com/photos/aerotowrelease/8316357172/





http://www.flickr.com/photos/aerotowrelease/8316503940/
http://www.flickr.com/photos/aerotowrelease/8315307555/
http://www.flickr.com/photos/aerotowrelease/8316505358/

This refinement is a lot more elegant but the principle and mechanics are the same.

This is launched armed and disabled/safetied at about two hundred feet by sliding the sleeve forward over the Trigger Line - at which point it essentially becomes a hand actuated barrel release.

It was originally a Three-String.

So the configuration and operation was EXACTLY what you're talking about here:

We will have another problem with the 3strings when used armed...

And as far as I know Steve's still using it that way except as a four-string.

In my adaptation it's never armed in normal use and one launches with the Trigger Line in his teeth and I advise spitting it out after two hundred feet or so to prevent accidental arming.

I advise arming it ONLY IF things start looking a little iffy down low to save one that step if things get worse and that puts one in Steve mode. But if one does that he's stuck with holding the Trigger Line in his teeth all the way up - or risk losing the tow trying to recleat it.

These emergency releases should be regarded similarly to parachutes...

- One should be able to get through a flying career without ever needing one.

- There's very little excuse for getting into a situation in which one is needed.

- If one DOES get into a situation in which one is needed - even if both he and the equipment function instantly and flawlessly - one can still die.

So you're probably never going to need to use it and, if you do, things are probably going to be happening so fast that you'll just abort the tow and skip arming mode.

However, if you did get it armed and started losing Trigger Line length as you describe...

You should be able to deal with it by climbing a bit above the tug, stuffing the bar to slacken the towline, and pulling the Trigger Line back to its stop.

So what did the guy at the end of the video get hooked to the cart and what happened to him?

And please tell me he wasn't using and relying on one of my Four-Strings which failed to actuate.

[deltaman]

The guy at the end of the video..
We met together in the center of France. We was surprised by a bad cart which was turning left everytime. Nevertheless we decided to use it.. Otherwise everybody went back home.
So, to correct that, pilots should move the tow point on the left side before to roll, it works for 45 AT in 2 days but this time this pilot probably didn't.

He had an Atos VR (big span) and setted bad its AOA on the cart. With too much angle (>10°), spoilers don't correct roll efficiently and spontaneously at start.
The man who assist on the left side we don't see on the vid was trapped in front of the leading edge as the cart was rolling left and the wings did some yaw. He was an obstacle.
The pilot lost the 4strings I gave him the day before and was using a barrel (straight pin) on the right side only.
He didn't think to release in time and that was difficult to do cause he had to let the cart on one side..
A mouth release would have been perfect here but regarding my own video, I'm not sure he could have release in time with an armed 4strings..

[Tad Eareckson]

Boy am I glad a Four-String failure had nothing to do with that one. I'd have felt totally horrible if it had.

I think the Three-String will do just fine - and it sure would be great to get a video of one being used to abort in an emergency like that.

So I'm guessing he wasn't hurt? How did the glider do?