Yiannis Mitzas

XF4U-3B Corsair

CHANCE VOUGHT’S
XF4U-3 WAS AN
ATTEMPT TO TURN THE
MIGHTY CORSAIR
INTO A HIGH-ALTITUDE
INTERCEPTOR. WE
EXAMINE THAT
AIRCRAFT WHILE
ALSO PRESENTING SEVERAL LESSER-KNOWN CORSAIR VARIANTS

Increased top speed and high-altitude
performance was the design goal of
Vought Sikorsky proposal VS-331,
which, in Navy designation became the
XF4U-3. Under the direction of Contract
Number 198, Lot One, Item Four, two
F4U-1As were ordered to be modified into
XF4U-3 configuration with the addition of
larger, more powerful engines, turbosuperchargers, and four-blade Hamilton
Standard Hydromatic propellers replacing
the -1’s three-blade props. Each F4U-1A
cost $98,385.96 and Chance Vought was
awarded another $98,884.93 to complete
the conversions to XF4U-3 configuration.
The most visible external difference of the XF4U-3
was its fourblade Hamilton Standard
propeller and the turbosupercharger’s airintake scoop located on the aircraft centerline just ahead of the lower cowl flaps.
Plans called for the installation of Pratt &
Whitney XR-2800-16 engines and
Birmann-type XTT13-14 turbosuperchargers in both aircraft. The Birmann-type turbosuperchargers were sealed units —
unlike the exposed General Electric turbosuperchargers carried on the Lockheed P38, Republic P-47, and Boeing B-17.
At military power, the turbosupercharged XR-2800-16 could develop 2000-
hp, continuous, or 2700-hp maximum at
25,000-ft versus the F4U-1’s waterinjected R-2800-8W, which could
deliver 2250-hp continuous, or
2700-hp maximum at 22,500-ft.
The first of the two Corsairs
to be converted, BuNo17516, received the XR-2800-16. This aircraft, designated XF4U-3A #1, made its
first flight on 26 March 1944, with
Chance Vought test pilot William “Bill”
Horan at the controls.
Delivery of the second prototype was
held up due to delays in delivering additional XR-2800-16 radials. Chance
Vought suggested to the Bureau of
Aeronautics that the R-2800-14W engine
be substituted. The water-injected R-2800-
14W could develop 2100-hp continuous,
and 2800-hp maximum at
28,500-ft at military
power settings. Although the -14W
engine did not
have the performance rating of
the -16 radial, it

XF4U-3B Corsair