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Vought XO4U Corsair

The Vought O4U Corsair was the designation applied to two different experimental biplane scout-observation aircraft.

Neither reached production nor entered regular service.

Ordered by the United States Navy in 1930 as the third type of “lightweight” observation aircraft designs, along with the Keystone XOK-1 and the Berliner-Joyce XOJ-1, both of which were built to BuAer Design No. 86, the XO4U-1 was completed to a somewhat different specification.

The Vought XO4U-1, BuNo A-8641, was built in 1931, and was Vought’s first airplane with a deep monocoque two-place fuselage and had a metal and fabric-covered metal wing structure. 

Both sets of wings joined the fuselage ahead of the pair of cockpits with the pilot seated in a cut out on the trailing edge of the shoulder-mounted slightly swept upper wing.

Photos show the airframe in the factory, fitted with teardrop-shaped wheel pants, but exterior pictures taken during its brief existence do not show these installed.

Powered by a 500 hp (370 kW) Pratt & Whitney R-1340D Wasp 9-cylinder air-cooled radial engine driving a two-bladed fixed-pitch propeller.

Although designed to serve either as a landplane or on floats, floats had not been fitted before the prototype was destroyed.

After the crash of the XO4U-1, Vought produced a new airframe which was designated the XO4U-2, and assigned the same serial carried by the XO4U-1, A-8641, although several lists of U.S. Navy aircraft serials make no mention of the second design, or the reuse of the Bureau of Aeronautics number.

The same practice was applied to the three Grumman XF3F-1 prototypes, two of which crashed, with all three carrying the same serial number.

This was actually an O3U-3 Corsair featuring that model’s rounded fin and rudder, an all-metal wing structure, and was fitted with a cowled Pratt & Whitney R-1535 Twin Wasp Junior, and first flew in June 1932.

Aviation historian William T. Larkins observes that under the designation system the XO4U-2 should have been a minor modification of the XO4U-1.


The Vought O4U Corsair was the designation applied to two different experimental biplane scout-observation aircraft.

Neither reached production nor entered regular service.


Prototype light observation scout


A second prototype of different design but carrying the same serial number as the XO4U-1.





27 ft 9 in (8.46 m)


37 ft 0 in (11.28 m)


1 × Pratt & Whitney R-1340D Wasp,

9-cylinder air-cooled radial engine,

500 hp (370 kW)


Maximum speed

143 mph (230 km/h, 124 kn)

Service ceiling

21,200 ft (6,500 m).


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