Which Vought aircraft was born from a cancelled fighter and was the first in its class to exceed 320 km/h?

The XF3U was the prototype of a two-seat biplane fighter, built entirely of metal by the Vought Aircraft Company of Dallas, Texas, for the US Navy. The Navy lost interest in two-seat fighters, so only one XF3U prototype was built. That aircraft reached 208 mph (334 km/h). The XF3U later evolved into a dive bomber and became the XSBU prototype of the SBU-1 Corsair. In fact, it was redesignated XSBU, meaning "scout bomber."

The SBU's design was based on the two-seat F3U-1 fighter, abandoned when the Navy decided not to acquire more two-seat fighters. The Corsair was the first aircraft of its category, the scout bomber, to fly at more than 200 mph. Its top speed was 178 kn (205 mph, 330 km/h) at 8,900 ft (2,700 m).

The aircraft had an enclosed cockpit and fixed landing gear, powered by an air-cooled Pratt & Whitney R-1535 radial engine similar to the F3U-1's. It also featured a controllable-pitch propeller and a new NACA cowling with adjustable trailing-edge gills. The SBU-1 completed flight testing in 1934 and entered production under a contract awarded in January 1935. The last SBU Corsairs were withdrawn from active service in 1941, reassigned as trainers.