The Boeing XP-7 (Model 93) was an experimental fighter used to test the Curtiss Conqueror engine. It was produced from the last aircraft of the PW-9D order, which was kept at Boeing to be modified.
The XP-7 was powered by a 600hp Curtiss Conqueror V-1570 inline engine, a larger and more powerful version of the 435hp Curtiss D-12 used in the PW-9. The XP-7 had a shorter, deeper nose than the PW-9.
The XP-7 was delivered on 4 September 1928. The engine was judged to be a success and the Air Corps drew up a specification for four service test P-7s. There was also some though of producing a PW-9E, powered by the Conqueror. The Army then decided that the PW-9 had really come to the end of the line, and that Boeing had better models under development. The project was cancelled and the XP-7 was converted back to the PW-9D standard by the army.
The XP-7 and the XP-9 were the last Boeing fighters to use liquid cooled engines. The Navy had decided to introduce air-cooled radial engines during the production run of the Boeing FB (their version of the PW-9), and the Boeing P-12 would be powered by a Pratt & Whitney radial engine.
Engine: Curtiss Conqueror V-1570 inline engine
Span: 32ft 0in
Length: 24ft 0in
Height: 9ft 0in
Empty Weight: 2,358lb
Gross Weight: 3,260lb
Maximum Speed: 167.5mph at sea level, 163mph at 5,000ft
Climb rate: 1,867ft/ min