The Curtiss XP-22 is one of the steps in the convoluted process of evolution and adaptation which produced the famous Curtiss P-6E pursuit. It was basically the third P-6A (Ser No 29-262) which was used to test new radiator and oil cooler installations for a V-1570-23 engine. Under the bizarre designation scheme used by the Army during the late 1920s and early 1930s, the experimental use of a different engine was thought to call for an entirely new designation, and the aircraft was redesignated XP-22. Final modification produced an entirely new nose, with belly radiator and oil cooler, machine guns lowered to troughts on the sides of the fuselage under the engine cylinder banks rather than between them as on previous versions. A new single-leg undercarriage was also installed.
The XP-22 flew for the first time in June of 1931. Weights were 2597 lbs empty, 3354 lb gross. During tests, the XP-22 achieved a maximum speed of 202.4 mph at sea level and 195.5 mph at 10,000 feet. Initial climb rate was 2400 ft/min, and an altitude of 5000 feet could be attained in 2.3 minutes. Service ceiling was 26,500 feet. Armament consisted of a pair of 0.30-cal machine guns mounted on the fuselage sides and synchronized to fire through the propeller arc.
In June 1931, a flyoff was held between a standard P-6, a standard Boeing P-12, a YP-20 with the Cyclone radial, and the XP-22. The XP-22's speed of 202.5 mph at sea level gained it the upper hand over all its rivals, and won it an order for 46 service test versions under the designation Y1P-22. However, for budgetary reasons, this designation was changed to P-6C and finally to P-6E before the planes were delivered.
After the tests were completed, these new features were removed from the XP-22 and were replaced by the original equipment, and the aircraft reverted to a standard P-6A.