Based on combat accounts of encounters between the F4F Wildcat and A6M Zero, on 26 April 1942, BuAer directed Grumman to install the more-powerful, 18-cylinder Pratt & Whitney R-2800 Double Wasp radial engine – already powering Chance Vought's Corsair design since its own beginnings in 1940 – in the second XF6F-1 prototype.