Ok. So I plan on building the Affordaplane A-plane. This is a question for you design/Engineer types out there. The main fuselage frame material is 2x2 aluminum square tubing (t-6 of course). My question is this: is square tubing a better choice than round? I'm told that square tubing would buckle if it got bashed, whereas round tubing is more structurally sound and would be less likely to buckle if it was bashed. Also, this design calls for foam ribs with aluminum cap strips. I've never heard of using foam ribs and it kinda scares me. Can anyone shed any light on the safety and structural effectiveness of using foam ribs? Also, since I'm a big guy (6'4, 300 lbs.) I know I'll need more than 40 hp, so I plan on putting in about 60 hp, which will weigh about 10-15 lbs more. Any suggestions on an engine mounting system, or is it best to let the engine mfg. suggest one?