This aircraft was one of several B. Douglas Thomas designs built in hopes of a production contract from the Army, following the successful Thomas-Morse MB-3 of 1919.

The XP-13 fuselage had a corrugated aluminum skin built over a metal frame; the flying surfaces were also metal-framed, but covered with the traditional fabric.

While designed to use the 600 hp Curtiss H-1640-1 Chieftain engine, (a novel 12-cylinder two-row air-cooled radial with the rear cylinders directly behind the front cylinders rather than staggered as normal in a two-row radial[3]) for which the XP-13 incorporated a complex system of baffles to direct cooling air over the engine, the engine simply would not stay cool enough, and in September 1930 it was replaced with a Pratt & Whitney SR1340C Wasp of 450 hp.

Ironically, the lower-power engine actually resulted in a speed increase of 15 mph, at least partly because of the weight savings.

[4] In the end, the Army decided against production, Thomas-Morse was acquired by Consolidated Aircraft, and the prototype was lost to an inflight fire.