Nate,

I have not made this conversion on a P-51, so I can't get specific on that design. I have done the same thing on another plane though. My guess is that a 3 piece design would be best. If your transport will allow, you could leave the center section attached and the gear down, limiting the connections needed during rig-up. It will also put the the joining tube away from the dihedral, which can be a problem.

When I added the wing tube, I cut oversized holes in the ribs where the tube (socket) passed. I also cut a series of light-ply donuts to fix the socket to the ribs when the alignment was right. Built everything up and with the sockets and tubes in place. Confirmed the wing was true, then started aligning the tube how I wanted it (donut loosely in place already) and started gluing the donuts to the ribs and sockets. I would recommed the larges tube and socket that will reasonably fit in the wing. On my bird, I used a second tube and socket in the rear for assembly alignment. If you do that you have to assure that the tubes are parallel or assembly is difficult to impossible.

The point of highest stress is the mating surface between the wing sections. I included a plywood rib at this point, on both surfaces to distribute the loads throughout the wing.

Others may have a simpler or better approach, but this worked for me and my bird.

Good luck!

Bedford