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Old Sep 27, 2012, 02:18 PM
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Dance the skies...
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United States, MA, Walpole
Joined Dec 2003
19,021 Posts
Quote:
Originally Posted by acreative View Post
Hi all,

relative newbuilder here needing some advice

Am building the FFF eagle (46") and was wondering what people were using as a wing-brace? I've build wings before with a wooden dowel etc. to strengthen but can't see how i could do it with this wing without the top 2 layers sticking up!

Are you all using flat carbon strips?

Also... how do you get a decent dihedral on the wings whilst still keeping them strong?

The next step is to somehow glue the V-shaped tail feathers?? That's another mystery lol

Thanks for any advice... i'll get there in the end!

Tim
I used my dremel tool to create two span-wise very shallow trenches (e.g. 1mm) in the top and bottom wing surfaces opposite each other. The I used epoxy to glue the wings together with my desired dihedral. Once that was firmly set, I laid a thin layer of 1 hour epoxy in the upper wing trenches, and laid 12K CF ribbon tow strips in the still liquid epoxy, then laid down another thin layer of the same epoxy on the top surface of the CF tow strip, and worked it down into the tow weaving with a flat wood stick so it was essentially flush with the wing surface. Once the CF tow was fully impregnated with epoxy, I let it cure, then repeated the process on the underside of the wings. Once painted, the strips are invisible for all practical purposes.

The eagle flies very slow, so the wing loading is not very severe and the tow strips provide more than adequate strength unless you have more power than needed. The wings have easily survived both slow inside and outside loops, but I seldom do that since it's not meant to be an aerobatic plane. Here's some pics:
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