I showed the fuselage on it's side - - --Imagine an I beam-the sides are top and bottom -the floor in centre is the upright
Each side is laminated balsa -light stock - bonded at 90 degrees .
the bulkhead is als laminated
The spruce carries the load fore/aft - the floor does two things: It makes the fuselage absolutely rigid against any "racking"
secondly the exhaust system is below - isolated from anything else.
Frankly I think the current structures used by many ARFS - is simply archaic--