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