The Sikorsky XSS was a 2-seat amphibious flying boat built by Sikorsky for evaluation by the United States Navy in 1933, as a carrier-borne and or catapult launched scouting duties.The XSS-1 was powered by a 550 hp (410 kW) Pratt & Whitney R-1340D Wasp engine in a strut mounted pod above the centre-section of the high-mounted gull-wing, forward of the cockpit which was aft of the wing.[1][2]