The Wings I would think. it's a pretty close copy of a Ryan the only giveaway is the thin prop no exhaust stubs and there is a pylon on the fuselage in front of the forward cockpit for the landing wires and to make egress easier when it's upside down on the ground. Good looking job. Nev
The DESIGN should have covered that aspect provided your materials and construction methods are Aircraft standard or to the design specs. If you are using wood it's more difficult . You need to be quite knowledgeable on wood selection, grading and application . Test pieces are subject to measured loads, to make sure they exceed the required material specs. Glued joints, specifically should be thoroughly tested.
There's a lot of this info on the American scene where homebuilts were well served with useful information. Tony Bingelis sp? has authored a series of books an all aspects of homebuilt construction. Recommended. Nev