The F4U-4 was the last variant to see action during World War II.
Deliveries to the U.S. Navy of the F4U-4 began late in 1944. It fully
equipped several squadrons four months before the end of hostilities. It
had the 2,100 hp (1,600 kW) dual-stage-supercharged -18W engine. When
the cylinders were injected with the water/alcohol mixture, power was
boosted to 2,450 hp (1,830 kW). The aircraft required an air scoop under
the nose and the unarmored wing fuel tanks of 62 gal (234 l) capacities
were removed for better maneuverability at the expense of maximum range.
The propeller was changed to a four blade type. Maximum speed was
increased to 448 miles per hour (721 km/h) and climb rate to over
3,800 ft/min (1,180 m/min) as opposed to the 2,900 ft/min (884 m/min) of
the F4U-1A. The service ceiling also increased significantly from 37,000
feet (11,000 m) to 41,000 feet (12,000 m). The "4-Hog" retained the
original armament and had all the external load (i.e., drop tanks,
bombs) capabilities of the F4U-1D. The windscreen was now flat
bullet-resistant glass to avoid optical distortion, a change from the
curved Plexiglas windscreens with the internal plate glass of the
earlier Corsairs. Vought also tested the two F4U-4Xs (BuNos 49763 and
50301, prototypes for the new R2800) with fixed tiptanks (the Navy
showed no interest) and an Aeroproducts six-blade contraprop (not
accepted for production). Later versions were armed with two 20mm cannon
in each wing. There were some night fighter and recon versions, but few
were actually built.