4strings release

[deltaman]

He was injured: sternum broken and some vertebral compression but no neurological issue. He is fine now..
The glider has probably nothing but will have a pro check.
For the 3strings I need the L/A ratio. I will measure it but need a suitable setup for that.

[Tad Eareckson]

Sorry he was hurt, glad he wasn't hurt worse or didn't become the latest Steve Elliot.

I'll try to get some performance numbers on the Three-String but for the time being...

Bear in mind that in the US three-strings similar to this:

http://www.flickr.com/photos/aerotowrelease/8320997523/


have been used for surface towing - with the FULL towline tension going to them (not split by a bridle) - since the beginning of time and I don't know of any reports of overload issues.

I'm really bummed out by this Four-String issue. I have a tremendous amount of work in testing, documentation, and photographs that's just been deligitimized to some extent. I'm hoping that it's an issue with the material you're using but I rather doubt it.

[deltaman]

I'm hoping that it's an issue with the material you're using but I rather doubt it.

I don't think so, cause I tested "my" 4strings and the direct force needed to release was the one you wrote..
except if :

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.

but the release had 5 flights maximum..

[deltaman]

This week, a friend had part of his arm broken after a lockout.

Launch by cart with side wind. He didn't wait enough before to release the cart and banked immediately on the opposite of the wind.
He was in a lockout, at 15m above the ground.
The trike was in acceleration phase.
He had a wichard and didn't release.
The weaklink (110kg) broke.
He did a U-turn and fly downwind before to be stopped by a hangar and broke his elbow (compound fracture of olecrane).

I really defend the use of a mouth release but probably more in the Steve Kinsley's initial version. Because the multi-string is useful at this time of the take off already armed. Besides I think this is the only manner it should be used to react quickly enough. Then, at 100m you neutralize it with the tube:
http://www.flickr.com/photos/aerotowrelease/8316357172/

I tested the new 3 multi-string version and found 19kg as a minimum tow line tension to release. I'm asking if it is not still too much to release during the rolling phase or just in the first banked instant close to the ground ..I'm not sure.

As I had some mails with a Russian pilot, they all seems to use their mouth release since 3-4 years and it works fine.
http://www.e1.ru/fun/photo/view_pic.php/t/bbae0dcfed7a6c0a2549eb93dfac82ea/view.pic

Until we hadn't the real tensions at all stage of an aerotow it's difficult to recommend the 3 multi-string version.

[Tad Eareckson]

This we, a friend had part of his arm broken after a lockout.

Better than being killed.

He didn't wait enough before to release the cart and banked immediately on the opposite of the wind.

Sounds like it's been a bad week for coming of the cart early in your neck of the woods.

He had a wichard...

One or two point towing?

...and didn't release.

Brake lever? Downtube? Basetube? Loop? Shoulder?

The weaklink (110kg) broke.

Bridle or towline tension?

He did a U-turn and fly downwind before to be stopped by a hangar and broke his elbow (compound fracture of olecrane).

Ooh.

I really defend the use of a mouth release but probably more in the Steve Kinsley's initial version.

Sounds like he was towing one point then. And I'd guess that 110 kg was bridle tension - 220 kg / pounds 485 towline. What flying weight and glider model? (If this was, in fact, 220 kg towline we'll be able to say, "See? Low level lockout, two G weak link still blows, would've been fine except somebody put the hangar in the wrong place.)

Because the multi-string is useful at this time of the take off already armed.

That's not a bad argument and that would be my preference - except the Clamcleat is a better, more reliable locking mechanism.

Besides I think this is the only manner it should be used to react quickly enough.

You can't get any faster than that, to be sure.

- But my position is that we can't afford to get into situations in which a half second's worth of advantage will make a difference - and we're capable of doing that.

- Also... If I were really compelled to launch in an iffy situation I could launch with the Clamcleat flavor armed and just hold the string in my teeth to altitude. It's not that much of an imposition.

I tested the new 3 multi-string version and found 19kg as a minimum tow line tension to release.

42 pounds - about a third of normal aerotow tension.

I'm asking if it is not still too much to release during the rolling phase or just in the first banked instant close to the ground ..I'm not sure.

I think you're fine. (Of course I thought everybody would be fine with the Four-String so...)

As I had some mails with a Russian pilot, they all seems to use their mouth release since 3-4 years and it works fine.

Not at...

http://ozreport.com/2013USNationalsrules.php
2013 US Nationals at Big Spring, Texas

2.0 EQUIPMENT

Appropriate aerotow bridles

Competitors must use appropriate aerotow bridles as determined by the Meet Director and Safety Director and their designated officials. Bridles must include secondary releases (as determined by the Safety Director). Bridles must be able to be connected to the tow line within two seconds. The only appropriate bridles can be found here:
http://OzReport.com/9.039#0

and:
http://ozreport.com/9.041#2.



Pilots who have not already had their bridles inspected during the practice days must bring their bridles to the mandatory pilot safety briefing and have them reviewed. Pilots with inappropriate bridles may purchase appropriate bridles from the meet organizer.

...anything controlled by Davis and/or his fellow pin bending sleazebags. But...

http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec

Brad Gryder - 2013/02/21 23:25:31 UTC

Sorry, but that's not the best answer. We don't live in a perfect world of quantum knowns and 100% reliabilities. Fine-tuning a weak link isn't going to get us but so far. There's also a way to swing your body way outside the control frame so it stays up there while you reach out with one hand and release. Come on - do some pushups this winter. See if you can advance up to some one-arm pushups.

...if they start doing pushups now they'll be fine by the start of the competition. Plus they'll undoubtedly be flying on...

Pilots must use weaklinks provided by the meet organizers and in a manner approved by the meet organizers. All weaklinks will be checked and use of inappropriate weaklinks will require the pilot to go to the end of the launch line to change the weaklink.

...some really safe weak links. And...

Pilots will be shown how to tie the weaklink so that it more likely breaks at its rating breaking strength.

...they'll be shown how to tie the weak link so that it more likely breaks at its rating breaking strength.

Until we hadn't the real tensions at all stage of an aerotow it's difficult to recommend the 3 multi-string version.

Need any 130 pound Greenspot. It's probably a good time to buy surplus from Quest and Kitty Hawk.

But seriously... The Three-String will be fine. The Russian model will handle low tension better but it's a somewhat clunky chunk of metal that's never gonna offer enough of a real world advantage to be worth it.

[deltaman]

It was a Laminar 13ST.
The pilot is around 75-80kg clipped-in.
Wichard in a 1 point configuration.
110kg weaklink in the towline.

I tested the new 3 multi-string version and found 19kg as a minimum tow line tension to release.

42 pounds - about a third of normal aerotow tension.

!?

http://www.youtube.com/watch?v=RiqhAQ1dn2M

[Tad Eareckson]

It was a Laminar 13ST.

32 kg

The pilot is around 75-80kg clipped-in.

60/90 min/max

110kg weaklink in the towline.

Damn. That helps the enemy.
- 1.0 times actual flying weight
- 0.9 times max flying weight

!?

What? Did I screw that up? I measured 125 pounds / 57 kilograms on my (kingposted) Wills Wing HPAT 158 at about 320 pounds behind a 914 Dragonfly.

Wichard in a 1 point configuration.

Direct or split load? Picture?

[deltaman]

!?

What? Did I screw that up? I measured 125 pounds / 57 kilograms on my (kingposted) Wills Wing HPAT 158 at about 320 pounds behind a 914 Dragonfly.

As I tested the 4 strings (my video) we saw a slack lanyard at different phases. Normal tow tension was less than the minimum tow line tension required to release: 27.2kg. So the 19kg required by the new 3 multi-string version is not "a third of normal aerotow tension".

Wichard in a 1 point configuration.
Direct or split load? Picture?

Direct load with the ring of the towline.
http://basses-lkah.com/l-kah/images-forums/largueur.jpg

but with a wichard :
http://t3.gstatic.com/images?q=tbn:ANd9GcTxvMhUHUteMiIpBuE6gvsP5-fj9xiHizYtM27UqLSGlJnKaxcX9plPFxfZ

[Tad Eareckson]

Well, I don't know what's going on then. 125 pounds is in the ballpark of what you'd expect to have to achieve those rates of climb based on the pretty good numbers we've always had from surface towing.

As much as I hate to say it seems that this issue is best addressed by putting things in the air and seeing how they feel and perform.

Be advised, however that I'm not softening my stand on Rooney caliber dickheads who are always spouting off about "TEST PILOTS" - because the implication is that if the equipment doesn't perform exactly as expected/predicted the only thing that has any possibility of standing between the pilot and certain death is a well and recently packed parachute. We're just trying to tweak things and even when our stuff malfunctions a bit we're still ten times better off than we'd be with Industry Standard crap with long track records.

Do try to get keep getting more of that overbuilt under-engineered junk in the photos out of the air. France is by far my greatest hope for seeing problems getting fixed.