In May 1928, the USAAC issued a single-seat fighter specification to which Boeing responded with a shoulder-wing all-metal monoplane, the Model 96, which was assigned the official designation XP-9. Low development priority and production problems delayed the planned delivery date of the XP-9 from April 1929 until September 1930, the aircraft eventually flying for the first time on 18 November of that year. Powered by a Curtiss V-1570-15 liquid-cooled engine rated at 600hp, but actually delivering 583hp, the XP-9 featured a semi-monocoque fuselage of sheet Dural over metal formers. Performance proved disappointing, the poor vision from the rear-positioned cockpit and the unpleasant handling characteristics resulting in the test pilot referring to the XP-9 as "a menace". After initial tests, the original vertical tail surfaces were replaced by larger P-12 surfaces, but little improvement resulted and the USAAC did not exercise its option on five Y1P-9s.