Boeing XP-15

The Boeing XP-15 was an American prototype monoplane fighter, essentially a monoplane version of the Boeing P-12 biplane with the lower wing omitted, all-metal construction and altered ailerons, a split-axle undercarriage and a tail wheel. Boeing numbered it the Model 202, and the United States Army accepted it for testing under the designation XP-15 without ever buying it, so it kept its civil registration X-270V. It first flew in January 1930, needed a larger vertical stabilizer to make up for the single wing, and recorded 190 mph at 8,000 ft with enlarged tail surfaces and a Townend cowling. The Army Air Corps found its rate of climb poor and its landing speed high and ordered no production, and the prototype was destroyed on 7 February 1931 when a propeller blade failed. A similar Model 205 first flew in February 1930 and one was bought by the US Navy as the XF5B-1.