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Old Jan 04, 2012, 11:45 AM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Yes, I have and use a high start. I just know that a wing can be a bit more tricky than a conventional tailed sailplane. Just as CG can be a bit more touchy on a wing, in my mind tow hook placement could also be a bit more critical. I have several foamie wings (not to be posted here other than brief mention ) including a finless one of my own design. Just never built or flown a thermal type wing yet.

Mark
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Old Jan 04, 2012, 01:27 PM
less is more
Knoll53's Avatar
United States, CA, Marina
Joined Sep 2006
2,651 Posts
Bungee launch

Got it Mark.

Since we're on the subject of launching, do any of you skinny wing guys favor the bungee launch? Currently my favorite due to the small space requirements is the bungee. It is a good test for flutter.

Kent

Horti parachute landing with just elevons (0 min 48 sec)
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Old Jan 04, 2012, 01:59 PM
Needs brain lubrication
biber's Avatar
Aachen, very western Germany
Joined Dec 2004
1,391 Posts
The first rc winglet wing glider I built myself has never seen anything other than slope and bungee.
It was constant chord (160 mm), 27° sweep, 116 cm span and 2° of linear washout.
It had hotwired XPS cores (Selig airfoil S5010) with one layer of bias cut 200 g/m² carbon cloth as skin.
No shear web, no spar caps.

I was terribly afraid it could be prone to flutter and that was why I made it torsionally stiff like hell.
I also made very stiff linkages between the servos and elevons.

It never had even the slightest flutter issues, but killed quite some servo gears during landings
(linkages to stiff, elevons to heavy, wingtip hits ground, elevons inertia beats teeth out of servo gear, et voila).

The hook was located way in front of CG on the nose of what once had been a HLG fuselage cut 10 cm behind the wing saddle.

biber
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Old Jan 04, 2012, 02:44 PM
less is more
Knoll53's Avatar
United States, CA, Marina
Joined Sep 2006
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Quote:
Originally Posted by biber View Post
It was constant chord (160 mm), 27° sweep, 116 cm span and 2° of linear washout.
It had hotwired XPS cores (Selig airfoil S5010) with one layer of bias cut 200 g/m² carbon cloth as skin.
biber
Wow, that sounds like a lot of carbon for such a little wing. I assume that this was a bagged wing. Yes, I believe you when you say it did not flutter. Even though it did not have longitudinal fibers along the span, I'll bet that it did not bend either.

Good to know that it bungee launched well. My guess is that you have developed a more economical, yet still stiff, reinforcing method since those early days. Of course you can't beat the look of all that carbon.

thanks,
Kent
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Old Jan 04, 2012, 05:07 PM
Needs brain lubrication
biber's Avatar
Aachen, very western Germany
Joined Dec 2004
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The cost of the carbon cloth was not all that much, as the rather heavy stuff is the most cheap type available and the wing was small.
I guess it was about 15 euros worth of carbon.

And I liked the look very much at that time.

It weighed about a pound and hasn't been thermaled ever, it just didn't seem to lend itself to floating.
However, back then my own experience with thermals was also close to zero.

Today I'd be tempted to apply the Mubu scheme to a 2 m thermal wing and see what happens.
I think a bungee would be the appropriate launching method for that, if not the classic javlin launch like in old HLG days.
I hate the hassle of lengthy highstart equipment.

biber
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Old Jan 04, 2012, 11:32 PM
internet gadfly
nmasters's Avatar
Colorado
Joined Aug 2006
2,145 Posts
Quote:
Originally Posted by biber View Post
Today I'd be tempted to apply the Mubu scheme to a 2 m thermal wing and see what happens.
Great build log, biber

The spar layup schedule shown in post #236 is the best I've seen in a model.

--Norm
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Old Jan 05, 2012, 06:44 AM
Needs brain lubrication
biber's Avatar
Aachen, very western Germany
Joined Dec 2004
1,391 Posts
Thanks Norm.

Maybe at last some of the stuff we are getting told in university was of use there.

biber, waiting for a video of Verns thermal wing to drool over *hint*
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Old Jan 05, 2012, 06:49 AM
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Vernon Hunt's Avatar
Florida
Joined Mar 2005
806 Posts
biber,
I'm waiting as well. The weather in Florida has turned very cold and windy, so it may be suitable to fly this weekend. I have my son and his camera on stand by to video the test.

Vern
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Old Jan 07, 2012, 04:06 PM
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Florida
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OK, Here is the vid of the test flight. It went well. Very first flight was great, went up pretty good. I need to bend my hooks flater for better tow.

Vern
Untitled (1 min 23 sec)
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Old Jan 07, 2012, 04:10 PM
Designing something...
United States, CA, Cameron Park
Joined Jan 2004
1,650 Posts
Nice Vern. Great job!!! We may need to design one of those with a built up structure. We should talk.

Brian
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Old Jan 07, 2012, 04:13 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Very nice and smooth. Congratulations on such a nice and smooth first flight.

Mark
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Old Jan 07, 2012, 04:17 PM
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Germany, Nordrhein-Westfalen, Nettetal
Joined Jun 2003
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Great maiden flight,

Wolfgang
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Old Jan 07, 2012, 04:25 PM
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Kent, UK
Joined Nov 2004
855 Posts
lovely job Vern, liking the 'power-lines limbo' too!
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Old Jan 07, 2012, 04:34 PM
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Florida
Joined Mar 2005
806 Posts
Hey! I knew it would be successful, but the power lines did cause a bit of intimidation. Thanks miniphase,cpdude, Quick61,quaxi, I'm enjoying after test multiple beers and ribs for dinner. It doesn't get any better than this. It's a tight spot to fly but close to home and nobody bothers you. More flights soon while the thermals are booming.

Vern
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Old Jan 07, 2012, 05:05 PM
less is more
Knoll53's Avatar
United States, CA, Marina
Joined Sep 2006
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Wow, that thing really FLOATS ! and no bad habits.
I would think that a skinny wing would move a little faster.

What was your final flying weight?

Kent
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