The Great Lakes XSG was an amphibious observation aircraft developed in the United States in the early 1930s for a US Navy competition. It was an ungainly and unorthodox biplane design with a single large pontoon mounted below the lower wing. This pontoon extended rearwards and carried the conventional empennage. On top of the lower wing where the fuselage would normally be located was a stubby nacelle containing the tractor-mounted engine and the pilot's cockpit.
Made by Great Lakes Aircraft Company.