durabol
Well-Known Member
I want to have an integrated spar box/landing gear attachment location for removable cantilever wing panels (glider style). For the spar box (with build in dihedral) I was thinking of using plywood reinforced with fiberglass with a fork/tongue or a single overlapping design attached with a single pin (through beefed up spar webs). I have heard that a folding wing adds 25-30lbs but this is all I have to go on. The stress analysis for this fitting is pretty complex and beyond me and I think a more practical approach of "will this work" and then load test the structure may be in order anyway. The sides of the fuselage and the ends of the spar box must be strong enough to take the upward bending load from the wing and the center of the spar box must be strong enough to deal with the "prying/downward" force of the ends of the spar inserts. These upward and downward forces result in a compressive force on the spar which is worse the shorter the spar inserts are which means a pretty beefy structure us needed. Does that sound right? I have seen some spar inserts are tapered which saves weight which would be okay if the center pin was taking all the shear force but that wasn't what I was planning. Anyone have any ideas? Are their any books or glider plans that could help?
Brock
Brock
