F6F Hellcat GrummanF6F Hellcat airplane model. The Grumman F6F Hellcat was ordered for the US Navy after the initial shock of Allied contact with superior Japanese fighters, particularly the Mitsubishi A6M Zero, during the first few months of the Pacific War. As a result of this experience of combat against higher performance machines the Hellcat's specification required the most powerful engine available. The prototype X6F 1, a progression from the F4F Wildcat which