In mid 1942, Grumman realized that it needed to concentrate on the production of its new F6F Hellcat fighter, and so it contracted with the General Motors Company to build the Wildcat under the designation FM-1. hundreds of which went to the Fleet Air Arm as the "Martlet Mk V." General Motors next developed an improved version, called the FM-2 , which was powered by a Wright R-1820 engine with 1,350 horsepower. It featured a taller vertical tail than the FM-1.
