Grumman designed its first single-seat shipboard fighter monoplane, the G-18, around the twin-row 14 cylinder Pratt & Whitney Twin Wasp engine. Awarded a prototype contract as the XF4F-2 on 28 July 1936. From October 1939, the XF4F-2 aws subjected to thoroughgoing reword which was to result in the extensively changed XF4F-3. The most important change was the installation of an XR-1830-76 Twin Wasp with a two-speed two-stage supercharger. The F4F-4 differed from its predecessor in having manually-folded wings and armament increased from four to six wing-mounted 12,7mm guns. A total of 1168 was procured for US NAvy.