Corsair Mk.3

Gareth Windsor
The final series version of the Corsair manufactured during World War II was the F4U-4, first projected mid 1943. The first prototype, a modified F4U-1 redesignated F4U-4XA, was flown on 19 April 1944, followed on 12 July by a second prototype, the F4U-4XB. The first series F4U-4 flew on 20 September 1944, and the initial aircraft of this sub-type was accepted by the US Navy five weeks later, on 31 October, with 500 being delivered by the following April. The principal changes between the F4U-4 and the preceding series model were provision of an R-2800-18W (R-2800-42W in later series aircraft) with water injection boosting the normal maximum rating of 2,100 hp to 2,450 hp, and a redesigned cockpit. The engine drove a new four-bladed, 13 ft 2 in (4,01 m) diameter propeller and was fitted with a down-draught carburetor, the intake ducts for which were moved from the wing leading edges to a position beneath the engine cowling. The standard sextet of 0.5-in (12,7-mm) guns was retained for the principal production series, but 297 were completed as F4U-4Bs with an armament of four 20-mm cannon. Goodyear was to have produced the F4U-4 as the FG-4, but orders for 2,371 FG-4s were cancelled following V-J Day and before completion of any examples of this model. Production of the F4U-4 by Vought continued, however, a total of 2,357 being delivered - including one F4U-4N night fighter and nine F4U-4P reconnaissance aircraft - with the final example being completed in August 1947.