04/30/2007. Remarks by Jack Mckillop: "This was a one-of-a-kind aircraft. The aircraft was tested at Wright Field, Dayton, Ohio, in June 1929 under the Project Number "P-559" and then purchased by the USAAC.
There were numerous cooling problems with the Curtiss Chieftain H-1640-1 twelve-cylinder two-row air-cooled radial engine and in September 1930, it was re-equipped with a Pratt & Whitney Wasp SR-1340C nine-cylinder single-row air-cooled radial engine and redesignated XP-13A. With the new engine, the Viper was 15 mph (24 kmh) faster than the original aircraft however, the aircraft crashed and was destroyed during an inflight fire and no others were ever purchased."
