Curtiss XP-46

The Curtiss XP-46 was a 1940s United States prototype fighter aircraft. It was a development of the Curtiss-Wright Corporation in an effort to introduce the best features found in European fighter aircraft in 1939 into a fighter aircraft which could succeed the Curtiss P-40, then in production.

Design and development
A United States Army Air Corps (USAAC) specification based upon a Curtiss proposal was the basis for an order placed in September 1939 for the XP-46. The requirements called for a single-engine, low-wing aircraft, slightly smaller than the P-40, and with a wide-track, inward-retracting landing gear. The selected powerplant was an 1,150 hp (858 kW) Allison V-1710-39 V-12 engine. The planned armament included two .50 in (12.7 mm) synchronized machine guns in the forward fuselage and provisions for eight .30 in (7.62 mm) wing-mounted guns. The USAAC later added requirements for self-sealing fuel tanks and 65 lb (29 kg) of armor, the weights of which were to adversely affect performance.

Testing
Two prototype aircraft were delivered, designated XP-46A, with first flight occurring on 15 February 1941. However, the USAAC decided in July 1940 (while the XP-46s were under construction) to replace the XP-46 procurement effort with an upgraded P-40 which would use the planned XP-46 engine. In this manner, a serious disruption of the Curtiss production line would be avoided.

Subsequently, the performance during trials of the XP-46 was found inferior to the upgraded P-40 (designated P-40D).

A myth surrounding the origins of the P-51 Mustang is linked to the North American Aviation (NAA) purchase of test data on the P-40 and P-46. NAA paid $56,000 to Curtiss for technical aerodynamic data on the XP-46 and although there are certain design similarities in the radiator/oil-cooler configuration, the new NA-73X (the company designation for the future P-51) even in preliminary design had already progressed beyond the XP-46. In addition, after the war, NAA engineers revealed that they had learned of a European study (before the US entry into World War II) which indicated the value of a well-designed embedded radiator, and were eager to apply that knowledge to a new design.