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Old Aug 09, 2012, 08:11 AM
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Couple of questions with a polyhedral gull-wing shaped flying wing

Hi guys,

I've been kicking around the idea of having a big flying wing, with a polyhedral gull wing design. I've made a little small scale glider and it flies pretty OK (see pic and video below). Thought I'd pick the various experts' brains before I started making prototypes.

1. How would I go about adding control surfaces? Not sure if traditional elevons will work on such severe dihedral and anhedral angles. Maybe a v-tail mix for the inner dihedral section and ailerons for the outer anhedral section?

2. How would I strengthen the bits where the wing changes angle? A straight carbon rod ain't gonna do it on this baby.

Appreciate the input guys .

Gullwing glide test (0 min 7 sec)
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Old Aug 09, 2012, 08:29 AM
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Wow, a bit extreme poly.. Maybe you would get away with a little less sharp an angle on the outer wing elements ! Meanwhile, could you inset carbon flat to foam in a straight line across the wing and where the angles are do a brace piece and make a taper to wing surface forward, leaving the back of brace flat (almost like a partial KF step).
Powering will be ummmm... interesting, maybe an in-slot pusher motor setup, but it will have to stick out the underside, otherwise a mid wing pylon with a really small prop. Only place after that is EDF perhaps (or just glider). Control surfaces... yes that's tricky ! Assuming you might be running ultra-light gear (like that on the vapour), maybe a central module with light piano wires to the inbound wing sections for an elevon style operation.
Interesting project... but radical at the same time. Good luck with it
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Old Aug 09, 2012, 08:43 AM
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Thanks for the reply, RWData. The chuck glider is a tiny prototype, I suspect the final version will have a 1.5m wingspan or so. Hence the need for strengthening of the joints .

Could you explain this bit again, I'm not sure I understand:

Quote:
Meanwhile, could you inset carbon flat to foam in a straight line across the wing and where the angles are do a brace piece and make a taper to wing surface forward, leaving the back of brace flat (almost like a partial KF step).
I have concerns about a pusher setup. If I am going to use the inner portion of the wing for control, then I want it to be in the prop wash. A tractor setup will let me do this. I am currently thinking of a tractor setup with a folding prop.

I considered an EDF, but the only one I have lying around in my parts bin is a 50mm hobbyking aluminium one, which apparently isn't very good.
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Old Aug 09, 2012, 11:22 AM
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Spar detail

Rayon... going from wing-tip to wing-tip (in about 30mm from absolute tip), 6mm x 1mm flat carbon spar on edge, inset into wing. Where the wing angle is, put another section of CS about 30mm long and thin wire wrap to each part of wing-spar, then thin epoxy-coat joins. This will leave a raised section of flat spar which you can feather out towards the front of wing using a bit of depron. thus making a sort of mini-KF and strengthening the wing join.
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Old Aug 09, 2012, 08:38 PM
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Ah, thanks. That makes it clearer. I will put it on the list of things to try when I build a prototype!
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Old Aug 12, 2012, 01:08 PM
"Five Easy Pieces"
United States, IN, Terre Haute
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reminds me of the "W" wing plane posted on RCGroups.
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