The Vought XSO2U-1 was an American observation floatplane developed during the late 1930s by the Vought-Sikorsky division of United Aircraft. This combined entity, which existed from 1939 to 1943, produced its military aircraft primarily at a facility in Stratford, Connecticut. The XSO2U-1 was specifically designed to meet United States Navy requirements for a catapult-launched scout aircraft to replace the Curtiss SOC Seagull. Key design specifications included folding wings to facilitate stowage aboard warships and a configuration optimized for superior range.
The prototype, assigned Bureau Number (BuNo) 1440, first took to the air as a landplane in July 1939, followed by its first flight as a seaplane in December 1939. The aircraft was powered by a 550 hp Ranger XV-770, an inverted V-12 air-cooled piston engine manufactured by the Ranger Engine Corporation. While the specific lead designer of the project is unknown, the aircraft's lineage was closely tied to the Vought-Sikorsky OS2U Kingfisher, which utilized similar all-metal construction and spot-welding techniques to ensure a smooth, durable fuselage.
During Navy evaluations, the XSO2U-1 proved to be technically superior to its primary competitor, the Curtiss SO3C Seamew. However, despite its performance advantages, the aircraft failed to secure a production contract. This outcome was not due to design flaws, but rather Vought's lack of manufacturing capacity to support a new production line alongside its other commitments. Consequently, only one airframe was ever built.
Following the competition, the U.S. Navy utilized the XSO2U-1 as a general utility "hack" aircraft. In July 1942, the prototype was transferred to the Ranger Engine Corporation to serve as a testbed for the V-770 engine, providing critical data for the development of the Edo XOSE floatplane and the Bell XP-77 lightweight fighter. After approximately two years of engine testing, the aircraft was returned to the Navy. Having no further utility, the XSO2U-1 was struck from the Navy's rolls on July 6, 1944, and subsequently scrapped. No examples of the aircraft survive today.