The Curtiss XP-42 was an experimental fighter built in the late 1930s to research engine cooling and improving the performance of the Curtiss P-36.
The fourth production P-36 (serial 38-004) became a development platform for a direct successor, designated XP-42 by the USAAC.
The XP-42 was powered by a Pratt & Whitney R-1830-31 engine fitted with a longer, streamlined cowling and a large propeller spinner.
These features attempted to improve the aerodynamics of the air-cooled radial engine.
Because of this feature, the XP-42 superficially resembled aircraft equipped with in-line liquid-cooled engines (such as the P-40, another development of the P-36).
When the XP-42 first flew in March 1939, it proved to be faster than the P-36.
However, the P-40 was faster still, and the new nose cowling caused engine cooling problems that proved to be unresolvable, despite at least 12 sets of modifications.
The XP-42 project was cancelled.
However, the XP-42 prototype was retained as a testbed and was later fitted with an all-moving tail (stabilator), for research purposes.
