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wayne ripley
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PostPosted: Fri Jan 06, 2017 5:51 am    Post subject: 3 point "pro tow" release Reply with quote #1   
I have tried to read the various aero tow release systems being used and I can't find one that I saw a Wallaby last week. Not wanting to buy a bicycle release and wanting to use a "pro tow"type release but I have an Eagle with a 14 inch forward tow point on the keel. Does anyone just tie off to the keel with a weak link and release from the barrel? The thing I worry about is the line getting wrapped around the "0" ring and not being able to release at all. any thoughts?
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brian scharp
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PostPosted: Fri Jan 06, 2017 7:45 am    Post subject: Reply with quote #2   
Quote:
Does anyone just tie off to the keel with a weak link and release from the barrel? The thing I worry about is the line getting wrapped around the "0" ring and not being able to release at all. any thoughts?

Sounds like a legitimate concern.
http://ozreport.com/forum/viewtopic.php?t=11591
Where to put the weaklink - the HGFA rules
Quote:
"Rohan Holtkamp - 2008/04/21

Once again history has shown us that this thread-through system can hook up and the hang glider remains being towed by the keel only, with the bridle well out of reach of even a hook knife. I know of just one pilot to survive this type of hook-up, took him some twelve months to walk again though".

And don't practice using the secondary first.
http://www.hanggliding.org/viewtopic.php?p=390548#390548
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dbotos
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PostPosted: Fri Jan 06, 2017 9:40 am    Post subject: Reply with quote #3   
Could stick a linknife at the keel attachment point:

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

Cheaper than the bicycle release (unless you burn through a ton of weak link line).

A wrap-up and subsequent keel-only tow sounds like a bad day. You might have to carry one of these instead of a hook knife:

https://www.amazon.com/Corona-LR-3460-Bypass-Pruner/dp/B000KL4LVI

Mr. Green
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Dave Gills
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PostPosted: Fri Jan 06, 2017 12:29 pm    Post subject: Reply with quote #4   
"Pro-Tow" is actually called a 1-Point release because you are only being towed from the shoulders.
If you have attachment points at the shoulders & keel it is called 2-Point.

An Eagle requires the 2-Point setup and 14" forward of where the zipper starts sounds correct.
The primary release should disconnect at the upper (keel) attachment point.

If you have a primary failure, followed by a secondary release & wrap, you will get dragged around by your nose.

The only way to avoid this, that I've been able to figure out, is to use a weak link on the primary that is lighter than recommended so it will blow if all the towing tension is applied to it.

My primary is a modified Russian mouth release & my secondary is a standard straight pin.

Here is me testing an Eagle with the above system.
https://www.youtube.com/watch?v=SpYdb-aIn6I

This is my recommendation for an "out of the box" primary release.
http://instinct.pro/products/get-off

Preflight your release EVERY time.
Failure to do so may kill you.

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ksykes
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PostPosted: Fri Jan 06, 2017 4:04 pm    Post subject: Reply with quote #5   
Wayne

What are you trying to achieve?
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Litespeeder
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PostPosted: Sat Jan 07, 2017 5:38 am    Post subject: Reply with quote #6   
Wayne,
I used to aerotow with this arrangement for quite a few years, oblivious to the potential problems with it. It was simple , clean , no need for the bike release. A few aerotow professionals warned me of the potential problems, finally our good friend Sunny Vaneski at Highland got it through my stuborn thick skull and I stopped using this arrangement. That was many years ago, since that time I use the "pro tow" on high performance gliders and 3 point with a bike release on single surface gliders. It was good hanging with you and your buddy mark [ litesport] and I forget the guys name with the trike, when you would come to Highland and camp and fly. I have a few bike release's I'll give you one if you need it, send me a PM or text two one 5 651 one zero 09
Jim Messina

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brian scharp
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PostPosted: Sun Jan 08, 2017 11:39 am    Post subject: Reply with quote #7   
Litespeeder wrote:
A few aerotow professionals warned me of the potential problems, finally our good friend Sunny Vaneski at Highland got it through my stuborn thick skull and I stopped using this arrangement.

Those few professional pilots were probably just over exaggerating the potential problems.
wayne ripley wrote:
Does anyone just tie off to the keel with a weak link and release from the barrel?

Apparently Paul Voight.
http://flyhighhg.com/wp-content/uploads/2014/08/G0017000f.jpg
http://flyhighhg.com/wp-content/uploads/2014/08/G0020205f.jpg
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brian scharp
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PostPosted: Mon Jan 09, 2017 8:52 am    Post subject: Reply with quote #8   
http://ozreport.com/forum/viewtopic.php?t=11655&postdays=0&postorder=asc&start=0
Wrapping bridles around loops, rings, links and carabineers
Davis wrote:
...First, as to the incident, this was actually a test and in the test Jim Prahl actually tied a rag to one end of the spectra rope on his shoulders so that it would be sure to catch and hold as the rope slid through the loop at the end of the V-bridle coming from the keel. He was trying to test to see if the weaklink at the keel end of the V-bridle line would break when the rag stuck. Well it didn't.

What happened when Jim released the barrel on his shoulder and the rag and bridle stuck in the line of the V-bridle, was that the nose of the Wills Wing Falcon pitched straight down instantly. Jim was left towing from the keel only at about a foot in front of the carabineer/hang loop.

Now Jim was not so dumb as to do this test without a backup plan (although he didn't expect the glider to pitch down so rapidly). He had the weaklink from the V-bridle line attached to a spinnaker shackle that was connected to a brake type release. He had his hand on the brake lever. When he released the barrel release, and the rag snagged the line, he didn't have time to hit the brake lever before the nose went over (and the weaklink didn't break). He then hit the brake lever and fortunately the glider recovered (it was a Falcon after all).

The point of this experiment was to see if it was okay to just release from the barrel release and do away with the expensive brake lever, cable assembly, and spinnaker release. Just connect the V-bridle line to the keel with a weaklink that would supposedly break if the shoulder line snagged in the loop (which I proved was possible). Jim proved that this was perhaps not a good idea.

Again, I have a direct personal and minor financial interest in the issues raised by this discussion.

Was there subsequent testing that found a weaker weaklink up to the task?
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wayne ripley
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PostPosted: Mon Jan 09, 2017 9:17 am    Post subject: 3 point pro tow release Reply with quote #9   
Now this is exactly the information I was looking for,it,s good to see that someone took it to the next level see what would happen. I,m not to worried about getting a good release at 2500 feet. I would think that I could brake the weak link with a hard push out. what I do worry about is a weak link brake or,being given the rope right off the cart. saving a few bucks but loosing my life[or worse] doesn't seem like a good trade off.
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brian scharp
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PostPosted: Mon Jan 09, 2017 9:29 am    Post subject: Reply with quote #10   
http://ozreport.com/forum/viewtopic.php?t=11655&postdays=0&postorder=asc&start=0
Davis wrote:
If you are going to tow all together from the chest and from the keel or carabineer, then have a release at the keel or carabineer end, not just a weaklink...

http://ozreport.com/goodies.php
Quote:
V-Bridle line, extra long 750 lb Vectran line, $20.
This is used connect to the keel (works with the Pro tow setup). You can connect to the keel through a weak link to a line attached to the keel, or through a bicycle/cable/spinnaker release, which is attached to a line on the keel. Vectran is used because it doesn't melt when Vectran or Spectra runs through the loop at the end of the line (if you release using a barrel release).

puke
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ksykes
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PostPosted: Mon Jan 09, 2017 2:49 pm    Post subject: Reply with quote #11   
If you release using the back-up barrel release is what it means..
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Rcpilot
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PostPosted: Mon Jan 09, 2017 11:57 pm    Post subject: Reply with quote #12   
brian scharp wrote:
Apparently Paul Voight.
http://flyhighhg.com/wp-content/uploads/2014/08/G0017000f.jpg
http://flyhighhg.com/wp-content/uploads/2014/08/G0020205f.jpg


WOW! Just asking for it! I hope that he keeps his parachute handy.

Perhaps Paul is not the best guy to be doing hang glider safety videos:


Link
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wayne ripley
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PostPosted: Tue Jan 10, 2017 4:51 am    Post subject: 3 point tow release Reply with quote #13   
As to whether or not Paul is a capable spokesman for safety in our sport should be undisputed,while it's not my job to represent him his over 40 year's of helping up and coming pilots speaks for it's self.
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brian scharp
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PostPosted: Tue Jan 10, 2017 1:30 pm    Post subject: Reply with quote #14   
Quote:
The point of this experiment was to see if it was okay to just release from the barrel release and do away with the expensive brake lever, cable assembly, and spinnaker release. Just connect the V-bridle line to the keel with a weaklink that would supposedly break if the shoulder line snagged in the loop (which I proved was possible). Jim proved that this was perhaps not a good idea.

Quote:
Now Jim was not so dumb as to do this...
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brian scharp
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PostPosted: Wed Jan 11, 2017 9:25 am    Post subject: Reply with quote #15   
MikeLake 2011/03/10 wrote:
...Towing from the top line only is an unbelievably dangerous situation, transferring to this mode due to some bottom line failure or hook up is likely to be even more dangerous.

When off the tow my 30 year old 2 point setup allowed for the belly cord to be disconnected so the rest of the contraption would wind up against the keel. I had a system in place where if this accidentally happened during the tow the line would automatically release.
(Note: This is not because I'm a brilliant designer or innovator or anything else. I watched someone tuck, didn't like what I saw, didn't want that happening to me, so I implemented a solution, simple.)
During my 23 year absence this 2 point setup (remnants of which are still in use today) morphed into something else and this safety feature was forgotten, abandoned or not understood.
I know of one fatality that I am sure would not have happened had that safety feature been in place. (*more on this).

I was fairly well stunned with the recent exchange at OZ speculating as to the likely outcome of this bottom line failure/hook-up.
No need to speculate all been done, tested and people killed or injured.
You would think with global commutations and a 30+ year history these lessons would by now all be common knowledge.
I really did attempt to get some sort of information exchange going to share this type of basic stuff.

*A knot came undone on the belly cord so all the load was suddenly transferred to the keel. THE KEEL FAILED and the pilot was killed.
A maintained, certified, 6g, 5th generation glider!
Readers! Where is the top attachment point on your set-up anything OUTSIDE of the sleeved area?
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