The Wildcat was planned as a biplane but then recast as a portly monoplane and flew in XF4F-2 form during September 1937 with a 1050-hp Pratt & Whitney R-1830-66 radial. Though fast, the type had a number of operational limitations, and was further refined as the XF4F3 with greater power, a larger wing, and revised tail surface The Wildcat was decisive in limiting the superiority of Japanese fighter in the Pacific theater, for despite is modest speed it was agile, heavily armed, well protected, and flown y good pilots. The type was also supplied to the British (initially as the Martlet), and production totaled 7,344. The F4F Wildcat was the US Navy's most important carrier borne fighter until replaced by the same company's  F6F Hellcat during 1943.