The Vought XSB3U was an American biplane scout bomber developed by Vought-Sikorsky for the United States Navy during the 1930s.

[2] Eight companies submitted ten designs in response, evenly split between monoplanes and biplanes.

The XSB3U was modified from the last production SBU Corsair,[3] using essentially the same airframe, including a fully enclosed cockpit, and Pratt & Whitney R-1535 radial engine, but with a more streamlined surface and cowling.

[4] The XSB3U-1 was delivered to Naval Air Station Anacostia for evaluation by the U.S. Navy in April 1936,[5] at the same time as its primary competitor, the XSB2U-1.

[4] Comparative testing of the two aircraft during 1936 proved the complete superiority of the monoplane configuration;[6] on the same power, the SB2U-1 was 15 miles per hour (24 km/h) faster despite being larger and heavier than the biplane.