Boeing XP-7

The Boeing XP-7 was a prototype United States biplane fighter of the 1920s. It began as the last Boeing Model 15 (PW-9D), serial 28-41, and was adapted to carry the 600 hp Curtiss V-1570 Conqueror engine; Boeing labelled it the Model 93. Its nose was shorter and deeper than that of the standard PW-9 and the aircraft was 75 pounds lighter overall. It first flew in September 1928 and did well, with a 17 mph speed increase over the PW-9. Even so, although a further four P-7s were proposed, the design was at the limit of its capabilities and already somewhat outdated at its first flight, and at the end of testing the Conqueror engine was removed and the aircraft was converted back into a PW-9D. The United States Army Air Corps was its only operator.