Vought XSB3U

The Vought XSB3U was an American biplane scout bomber prototype that Vought-Sikorsky developed for the United States Navy in the 1930s. It was proposed as a conventional alternative to the monoplane XSB2U-1 that became the SB2U Vindicator, after the Navy's Bureau of Aeronautics issued a late 1934 specification for new scout bomber and torpedo bomber designs. The XSB3U was modified from the last production SBU Corsair, with the same airframe, a fully enclosed cockpit and a Pratt and Whitney R-1535 radial engine, but with a more streamlined surface and cowling and fully retractable landing gear. It reached Naval Air Station Anacostia in April 1936, together with its monoplane rival, and the tests showed the monoplane about 15 miles per hour faster, so the biplane was not developed. The Navy kept it for experimental and liaison work, and NACA used it at Langley Field for tail load tests from August 1938 to January 1939.