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Jan 04, 2012, 11:45 AM
Just call me crash for short
Quick61's Avatar
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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Jan 04, 2012, 01:27 PM
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Knoll53's Avatar

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)
Last edited by Knoll53; Jan 04, 2012 at 05:48 PM.
Jan 04, 2012, 01:59 PM
Needs brain lubrication
biber's Avatar
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
Jan 04, 2012, 02:44 PM
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Knoll53's Avatar
Quote:
Originally Posted by biber
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
Jan 04, 2012, 05:07 PM
Needs brain lubrication
biber's Avatar
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
Jan 04, 2012, 11:32 PM
internet gadfly
nmasters's Avatar
Quote:
Originally Posted by biber
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
Last edited by nmasters; Jan 04, 2012 at 11:55 PM.
Jan 05, 2012, 06:44 AM
Needs brain lubrication
biber's Avatar
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*
Jan 05, 2012, 06:49 AM
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Vernon Hunt's Avatar
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
Jan 07, 2012, 04:06 PM
Registered User
Vernon Hunt's Avatar
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)
Jan 07, 2012, 04:10 PM
Designing something...
Nice Vern. Great job!!! We may need to design one of those with a built up structure. We should talk.

Brian
Jan 07, 2012, 04:13 PM
Just call me crash for short
Quick61's Avatar
Very nice and smooth. Congratulations on such a nice and smooth first flight.

Mark
Jan 07, 2012, 04:17 PM
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quaxi's Avatar
Great maiden flight,

Wolfgang
Jan 07, 2012, 04:25 PM
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miniphase's Avatar
lovely job Vern, liking the 'power-lines limbo' too!
Jan 07, 2012, 04:34 PM
Registered User
Vernon Hunt's Avatar
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
Jan 07, 2012, 05:05 PM
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Knoll53's Avatar
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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