This variant was introduced in April 1944, and was built in parallel with the F4U-1C. It had the new R-2800-8W Double Wasp engine equipped with water injection. This change gave the aircraft up to more power, which, in turn, increased performance. Speed was increased from to . Due to the U.S. Navy's need for fighter-bombers, it had a payload of rockets (double the -1A's) carried on permanent launching rails, as well as twin pylons for bombs or drop tanks. These modifications caused extra drag, but the additional fuel carried by the two drop tanks would still allow the aircraft to fly relatively long missions despite heavy, un-aerodynamic loads. A single piece "blown" clear-view canopy was adopted as standard equipment for the -1D model, and all later F4U production aircraft. 150 F4U-1D were delivered to the Fleet Air Arm.