F4U-2 Experimental conversion of the F4U-1 Corsair into a carrier-borne night fighter, armed with five .50 in (12.7 mm) machine guns (the outboard, starboard gun was deleted), and fitted with Airborne Intercept (AI) radar set in a radome placed outboard on the starboard wing. Since Vought was preoccupied with more important projects, only 34 were converted from existing F4U-1s by the Naval Aircraft Factory and another two by front line units.
Thirty four F4U-1s were converted into night fighters and given the F4U-2 designation. The main change was the installation of an air interception radar set. The radar antenna was placed in a radome (radar dome), placed two thirds of the way along the starboard wing. The outermost machine gun was removed from that wing to help balance the additional weight. As normal with night fighters, the exhaust stubs were modified to hide as much of the exhaust flame as possible. Three naval squadrons flew the F4U-2 night fighter in the Pacific (VF(N)-75, VF(N)-101 and VMF(N)-532). Only a small number of this version were built, and those aircraft moved between the three units as required. They were first used on Munda, New Georgia, where the Japanese were making nuisance raids at night. They also served on the U.S.S. Essex, U.S.S. Hornet and U.S.S. Intrepid. (Wiki)
"The prototype F4U2 was converted from the first production F4U1 during 1942. The first F4U2 flew on 8 January, 1943.
The XF4U2 differed from the standard day fighter by the inclusion of a microwave-pulse based, airborne interception XAIA radar unit mounted in a bulbous fairing on the front edge of the starboard wing, and the deletion of the outboard .50 cal. machine gun. The latter modification was made to compensate for the extra weight of the airborne radar. This weight reduction meant that the top speeed was reduced by less than kph when compared to the F4U1. A rudimentary 3-inch radar scope was also added to the centre of the main instrument panel.
The Radar
The production model AIA radar unit was intended to have a useful search range of 3.2 kilometres at an altitude of 600 metres or higher (Veronico and Campbell, p.48). The antenna mounted in a streamlined dome did not adversely affect the superb flying dynamics of the Corsair.
Into Service
The first Corsair night fighter squadron VF(N)-75, was formed in January 1943. However, the first night fighter squadron was not deployed in the Pacific until October, 1943.
By early 1944 all three US night fighter squadrons had been deployed - VF(N)-75 was a land based Naval squadron (something of a peculiarity): VF(N)-101 another Naval squadron but based on the USS Enterprise; and VMF(N)-532, a Marines squadron based in Tarawa.
Successes
Despite the technical success of the AIA radar, kills in the night Corsair were relatively rare. VF(N)-101 scored a total of 5 confirmed, 4 damaged and 1 probable between January 1944 and their disbandment in July of the same year (Veronico and Campbell, p.48).
VMF(N) - 532 also scored at least three victories.
The F4U2 was also quite successful in the role of nighttime and dawn harassment bombing and strafing. This success was despite the reservations held by some senior Marine flyers who believed that this type of operation was not appropriate for the highly specialised night-fighter pilots.
The F4U2 and its pilots were nevertheless successful as pioneers of night-flying tactics in the Pacific theatre.
No F4U2s were used operationally by any foreign Air Forces, although the Royal Navy may have evaluated one.
Successors
Despite the relatively brief service history of the F4U2 Corsair, it was significant because it spawned a new generation of US Naval night fighters. The night fighter versions of both the Wildcat and Tigercat owed their existence to the pioneering of the F4U2. In addition, its direct descendant, the F4U5N was widely used with great effect in Korea."
Source: BENT WING NIGHT BIRD
US Navy and Marines Night Fighters
Part One - The F4U2 Corsair
XF4U-3: Experimental aircraft built to hold different engines in order to test the Corsair's performance with a variety of power plants. This variant never entered service. Goodyear also contributed a number of airframes, designated FG-3, to the project. A single sub-variant XF4U-3B with minor modifications was also produced.
The XF4U-3 was designed to test out to possibility of fitting a pair of Bierman superchargers to the engine in an F4U, in an attempt to improve its high altitude performance. Work was carried out during 1943 and 1944, with test flights in April 1944. However, the superchargers were not reliable, rarely lasting for two entire test flights without a failure. April 1944 also saw the first flights of the F4U-4, and the dash three was abandoned in favour of the more conventional dash four.(Wiki)