ORIGINAL: nonstoprc
ORIGINAL: DaveL322
My comment(s) regarding balsa/foam wings showing evidence of wear - I know more than a few reputable builders that replaced foam/balsa wings every 500 - 1000 flights because they would develop flex - spanwise and in torsion. No risk of them failing, but the planes would not groove as well in turbulence. No doubt building the wings heavier to begin with would extend the life expectancy. I really don't see a problem with designing/building to a given life expectancy for the benefit of lighter weight.
Regards,
Could more carbon fiber cloth strips fix the span-wise flex developed later on? I know the common practice of building foam wings is to add two pieces as spars and one near the trailing edge. Maybe more strips should be used?
Carbon fiber strips added spanwise increase stiffness and strength in the span direction only. They don't help in torsion. Carbon veil applied with epoxy helps in both torsion and span stiffness. Adds a little weight but worth it in the long run
In my experience however, the construction technique that helps the most all around is vacuum bagging. I bag the wing panels, not the husks. The other thing I do that really increases strength is to take advantage of the socket. By building half span spars top and bottom surrounding the socket, and extending the spars to the skins, the structure forms an "I"beam. For the same weight or less than the false rib method, which only supports the socket and doesn't really reinforce much else, one can increase strength and stifness with minimal added effort and not really much weight increase at all.
BTW- the final word on this method hasn't been written yet either. I have built wing panels (around 500 squares) that weigh in at 8 ozs ready for finish. Silkspanning and painting adds another 3 ozs and servo and linkage another 2. That's the best I've done but there is room for improvement
FWIW2U