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Old 04-04-2019, 02:15 PM
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Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,555

Originally Posted by Silverback View Post
"A 3 or 4mm thick ply brace is more than enough with depth equal to the core depth." - Depth of what? What is the core depth? Do you mean a brace the same height as the thickness of the core? Or going the thickness of the core into the wing?

My best guess is to cut a brace as tall as the thickness of the wing core airfoil but I'm not sure how far into the wing... Going back to my stick building days typically the center of the wing would have a ply brace the height of the top to bottom spar going out a rib bay or 2... I'm guessing this is about what we're going for?
Depth would be top to bottom surface - so yes depth of the wing.

How far into the wing ... thinking about it - usually it would be anywhere from 1/2 to equal to chord of the wing root ... it really depends on what stress / style of flying. If sunday flying - then a simple brace of about 3/4 chord into each wing half is fine .... if you are into aerobatics (given the wing in your post - I doubt it !) then full chord or even more length into wing half would be sensible.

Any thoughts on using polyurethane in the place of epoxy? I've been on a "keeping this thing light" kick with this build and have mostly stayed away from epoxy and hot glue because of it. I shouldn't have any significant gaps (I cut the dihedral angle using a jig on a table saw, got a perfect cut, I'm very happy with how that turned out), but even so, polyurethane (GG) should fill small gaps and should still be stronger than the foam I'm gluing to.
You could do away with the bandage ... if you created holes into the cores roots and the GG was allowed to 'create foam spars' into them ....
Taking CF rods and tubes ... you could glue tubes into each wing and have a CF rod bridging the joint ... GG to join it all.

But I would not use GG with the bandage instead of resin .... the GG expands and would not anchor the bandage correctly - that's if you could wet it out even. There is another way to bandage ..... using nylon and PVA white glue watered down ... But then it takes time to dry out and cure.

For some reason that made me laugh... thanks
We all need a smile now and again ...
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