Making a big wing strong enough - RC Groups
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Jan 24, 2003, 10:48 PM
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FlyingW's Avatar

Making a big wing strong enough

I have cut foam cores for a large sailplane project: 12' span, 15" root chord, 9" tip chord. 4 sections, each 36" long.

I plan to use 3/8x3/8" spruce spars top and bottom for the root sections, aand 1/4x1/4" for the tip sections. I plan to use a 1/2" id aluminum tube and 1/2" carbon rod for the root joiner. Tip sections will have plywood joiners and be glassed together.

Here's the [art I'm struggling with: Should I cover it? I've used 3/4oz glass on a 7 foot wing with good success; no L.E. carving, etc. I may go to 1.4oz cloth and do the same for this 12' one.

Any experiences out there to share? Thanks.
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Jan 24, 2003, 11:02 PM
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Andy W's Avatar
You need to use 1/8" vertical grain balsa for the spar, and cap it on both sides with carbon tow. You're not 'covering' the foam, you're building a glass wing and using the foam to give it shape. It needs to be vacuum formed. You don't need to use heavy glass.