From "Mustang Designer - Edgar Schued and the P-51" by Ray Wagner
The design for what culminated in the P-82 began on 21 Oct '43 when Ed Schmued requested Howard Evans & Julius Villepique to investigate a twin fighter design, one conventional & the other the P-82 arrangement. Villepique says of the conventional arrangement, but does not elaborate, "it could not compete with the manifold possibilities offered by the dual fuselage arrangement".
Schmued wrote, "Many people think the F-82 is nothing else but two P-51 fuselages joined together by the wing. This is not the case. It was a completely new design. Nothing of the P-51, except the design principles and power plant group, was used on this new venture".
General Arnold during a visit to the plant on 7 Jan '44 gave the go ahead when shown the proposal. Contracts were approved 30 Jun '44.
First attempts at flight on a number of successive days were unsuccessful, later found to be caused by the centre section being stalled due to prop rotation direction. First flight was 12 Jun '45 in the unmodified state. Engines/props were removed and installed in the opposite location and the aircraft flown ten days later.