While these suggestions are well-meaning, the proper way to design a fuselage truss is not by Internet committee. YouTube and other basic resources are full of the principles of truss design--two-force members, elimination of zero-force members, aligning members to intersect at single-point joints, etc. Better to discuss those concepts than redesign Duncan's fuselage for him--especially since none of us has determined any of the loads on it. The depth of the truss beneath the seat may or may not be a problem depending on the loads imposed on it.
Duncan, I look forward to more progress. I like the concept and your persistence.
"Bad" is relative. This area is just one of those parts of an airplane that is hard to optimize because we have to accommodate the pilot. Fully triangulating the cockpit entry to eliminate indeterminate structure is really hard without using a door with a latch that can carry the structural loads. That brings problems of it's own.Still bad... the entire bending loads come down to the height between the back of the seat and the lower longeron,
And why we should use all of the resources available to us, such as a second set of eyes on the project, as is being done here ..... and math using conservative and verifiable material properties.In the end the responsibilities still lay at the feet of the designer.
That's not quite correct. Even with your "built in gusset", the gluing area isn't as much as a gusset glued on the side. But more importantly, gussets on the side load the glue joints in shear, which is what you want for a good glue joint. Your method loads the joints in tension, which is not good.The in-built gusset are a new idea, so no additional gussets are required