That part would need heavy engeneering in order to insert a structural removable axis between the composite receptacles. Not a very purist concept, but infusing that composite sandwich plate could be done in two days. I would add a non structural super light aerodynamic egg around the pilot.
Wonder how much torsional stiffness could be achieved by a thick sandwich panel, but the concept could be fast,
The small extra effort of running the upper longeron through the propeller hub is not insignificant, but it solves many other problems. It puts the thrust line in a better place. A belt redrive coupled with a V-twin conversion on this type of airframe would make a viable option IMHO.
A propeller hub made in two pieces, which clamp together around the upper longeron (and can be removed for maintenance/repair) would be a good idea if it is do-able at a reasonable weight. That way, only the actual thrust and radial bearing would be permanently trapped by the longeron.
I like it too. I daydreamed about a prop around the boom on my Kolb Ultrastar... having the prop under the boom limited the possible prop size, and putting it on top like the later Kolb models means big pitch changes with power. To belt drive it the boom would have to be removable for maintenance... tricky with a single bending loaded boom with cables inside, but much easier on a truss frame where you can just remove one tension/compression member.
Yes, a single layer, composite lay-up would be a quick way to build your second fuselage. The thicker it is, the less it will bend sideways.
May I suggest planning it with bolted structural joints in both the top and bottom longerons?
In almost-finished configuration, the bottom longeron could be hinged under the propeller. For added stiffness, it could overlap into a trough/trench/groove that reaches almost to the the main landing gear.
The top longeron needs to be built in 3 pieces. The first piece is the forward piece (permanently attached to wing and cockpit) that carries flight loads.
The second piece of the top longeron is the aft part which is glued/epoxied to the single sheet aft fuselage. It bolts on just aft of the propeller.
The third piece is a cylinder/tube that rotates around the structural top longeron. The cylindrical tube only carries power from the engine to the propeller. Hopefully you can install a bearing close to the prop ... even if it requires a pair of diagonal bracing struts.
To replace the propeller )or drive belt) you un-bolt the top longeron and hinge down the aft fuselage.
And to reduce noise, leave one bay of the aft fuselage uncovered until at least half the diameter of the propeller. You can still have thick longerons, just no covered vertical surfaces until you get as far aft as the fin.
Another poster suggested an electric motor with a huge hollow (10 inches?) through the drive shaft. But I suspect that requires an entirely new design of engine.
Meanwhile you are doing great with your first prototype. You will need many more evening hops to test its entire flight envelope. Enjoy those evening flights.
Makes Sense. With your proposal, the fusealge could be transported in two pieces with just an additional bolt.
The idea of making the tail out of composites makes sense as the tailfin could be seemlessly integrated with the tail cone sheet. The problem this construction type uses extensively struts and i hate struts.