Vought XF3U
The Vought XF3U was the prototype of a two-seat, all-metal biplane fighter, built by Vought Aircraft Company of Dallas, Texas for the United States Navy. Development and design. The XF3U was designed to meet the Bureau of Aeronautics 1932 "Design Specification No. 111", which called for a high-performance fighter with a fixed undercarriage and powered by a Pratt & Whitney R-1535 Twin Wasp Junior air-cooled radial engine. Of the seven proposed aircraft the XF3U and the Douglas XFD were chosen. The XF3U was the first all-metal aircraft produced by Vought. The aircraft was also  equipped with an enclosed cockpit. During flight testing in 1933, it outperformed the Douglas entry and was chosen the winner. Operational history. The Navy no longer was interested in two-seat fighters, and therefore only the one XF3U prototype aircraft was built. The XF3U subsequently evolved into a dive bomber, and became the XSBU prototype for the SBU-1 Corsair.