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Old Jan 03, 2012, 09:57 AM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
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Quote:
Originally Posted by Vernon Hunt View Post
Mark,

I've launched my skinny wings hundreds of times and it goes up like any sailplane. At the glider end of the bungee I use a bridle, that attaches to 2 hooks outboard on the wing just ahead of the CG. Works great.

Vern
Yes, That is like the rolling bobbin. It hooks to 2 hooks on the wing and has a ring or "bobbin" that is in the center that can slide at the Y junction. I first learned about the setup reviewing the plans for the Sparrow, an old timer forward swept flying wing. After a bit of a search I found the attached document on the subject. (just a single page)
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Old Jan 03, 2012, 03:54 PM
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Vernon Hunt's Avatar
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Here's what I have on this sunny afternoon. Controls are working, high and low rates. Need to get differential working.One hook is shown. Very beefy setup. multiple bends to sandwich between 3/32" ply. Then set into wing with epoxy.

Vern
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Old Jan 03, 2012, 03:57 PM
Designing something...
United States, CA, Cameron Park
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Very nice Vern! I definitely have a need to build a good (and light) thermal wing at some point.

Brian
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Old Jan 03, 2012, 04:04 PM
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Brian,

Thanks! Yes, these are great flyers, and pretty easy to build.

Vern
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Old Jan 03, 2012, 04:14 PM
less is more
Knoll53's Avatar
United States, CA, Marina
Joined Sep 2006
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Vern,

It looks bigger with you in the shot. Looks like a real floater now!

I've read about the wing mounted dual tow hooks but have not experienced it yet. From the looks of it, you'll get a typical very steep launch with a final release at low line force. I'd think that one hook releasing before the other could be "problematic". From what I read, it is not.

Also, once a line across the wing is established for the hooks, I'd think that you could place the symmetrically laid out hooks at any where along that line. I see that you have placed yours well forward of the spar rather than at the spar. Any reason for this besides personal preference?

thanks,
Kent
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Old Jan 03, 2012, 04:28 PM
Designing something...
United States, CA, Cameron Park
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Quote:
Originally Posted by Vernon Hunt View Post
...and pretty easy to build.
I'm sure it is with all of that foam.
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Old Jan 03, 2012, 04:36 PM
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Kent,

Yes, it can be slowed very nicely, once in a thermal set the bank and spin yourself up. Even at this light weight it can moveout quickly and seek new hot air. I've had a tow line ring come off during tow and it just kept going up, I couldn't believe it. The hooks should be right up close to the leading edge. The CG is right behind the hook placement. You are correct in saying the hooks aren't connected to the spar. But, I've never had a hook pull out with where they are, sandwitched between 3/32" ply and liberally glued to the top skin. With a block of balsa on top filling the remainder of the space essentially gluing it to the bottom skin.

Vern
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Old Jan 03, 2012, 04:44 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
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Quote:
Originally Posted by Vernon Hunt View Post
Here's what I have on this sunny afternoon. Controls are working, high and low rates. Need to get differential working.One hook is shown. Very beefy setup. multiple bends to sandwich between 3/32" ply. Then set into wing with epoxy.

Vern
Great looking wing. Any "rule" you are following on placement of the tow hooks, or is the placement one of those "experience tells me to put it here or else!" kind of things?

Mark

(now waiting on video of the launch. )
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Old Jan 03, 2012, 06:26 PM
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Mark,

I think I explained hook placement in my answer to kent just above your question. the hooks are placed 1/2" ahead of the CG on the leading edge.

Vern
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Old Jan 03, 2012, 06:35 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
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Quote:
Originally Posted by Vernon Hunt View Post
Mark,

I think I explained hook placement in my answer to kent just above your question. the hooks are placed 1/2" ahead of the CG on the leading edge.

Vern
Yes, I got the where they were placed. I was wondering HOW that place was picked (as opposed to 1/4" forward of CG or 3/4" forward) Sorry for not being more clear about my question.

Mark
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Old Jan 03, 2012, 06:51 PM
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Mark,

Placement depends on how you feel about your tow. Do you like a sensitive tow, then put the hooks very close to the CG. Or, do you like a more easy to control tow, then place the hooks further forward of the CG. I found 1/2" ahead of the CG to be a comfortable tow especially right after launch. Not a severe pitch up so the glider doesn't stall.

Vern
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Old Jan 03, 2012, 07:05 PM
internet gadfly
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Colorado
Joined Aug 2006
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Quote:
Originally Posted by Quick61 View Post
Yes, I got the where they were placed. I was wondering HOW that place was picked (as opposed to 1/4" forward of CG or 3/4" forward) Sorry for not being more clear about my question.

Mark
Herk Stokely talked about tow-hook placement in the Tinamou thread .
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Old Jan 03, 2012, 10:17 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Thanks guys. That helps out allot. Never launched a wing on a high start before so the more info I can gather before I build and try to fly the better my chances of avoiding a rekit. Appreciate your info and patience. This is all new territory for me.

Mark
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Old Jan 04, 2012, 03:45 AM
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Joined Nov 2008
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thermal wing

hello Mark,

I see what you mean now; I have no experience with it.

Maybe you can ask Tailsaw, he has a lot of exp. As far as I understand it, there is a great change of flutter.

http://thermik-board.de/nurfluegel-f...c7eb1cc4536695

Peter
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Old Jan 04, 2012, 09:13 AM
less is more
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United States, CA, Marina
Joined Sep 2006
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Quote:
Originally Posted by Quick61 View Post
but I can't say that I have seen a TD type wing being launched by high start.
Mark
Ooooooooh, you've "never launched a wing on a high start before".

Have you ever used a high start before? If not, then the answer is very different. Things happen very quick when you launch and I'd suggest that you learn it in steps. That is start with a very gentle pull and push the nose down for control. Then work your way up to a steep high force launch. Tow hook placement is of course critical.

Knowing your experience with this would help us give you a more useful answer. Much has been posted about high starts in general in the Sailplane section.

Kent
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