Main gear attachment location theory

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Well-Known Member
Mar 30, 2019
Somerville, TN
Good stuff, BIllski, thanks! I will order that book.
But more to the point of my rear spar carrythough question, I was taught in structures class that in beam design, you always have a fixed end connection and a pin connection when you set up your calc problem. I was under the impression that is so you get the actual action you want on the beam. If it can't deflect the 1.3 inches you calculated because the bottom of the beam can not move on either end, it.... I don't know... explodes? The Universe opens up into a black hole? I don't know... It puts other types of forces on the beam that you didn't calculate for? At any rate, I know it is a convention to do that. In my design, I have a main spar carry through under the aft butt of the front seats, just like most 4-places do (RV10, Sling TSi, etc.). But all I've ever seen with those is the rear cap spar or rear spar just connects with a single bolt to the inside of the fuselage instead of having its own carry through, and I was wondering if there was a reason for that similar to my experience in buildings beam design. Sort of like... "if you don't allow it to bend, it will break" kind of thing.
Any thoughts?