Sikorsky S-31

The Sikorsky S-31 was an American sesquiplane of the 1920s, designed and built by the Sikorsky Manufacturing Corporation and configured for aerial photography. It was built for the Fairchild Flying Corporation, with two open cockpits and a cabin for the photographic equipment, and was powered by a 200 horsepower Wright Whirlwind J-4 engine. It first flew in September 1925 and took part in the New York Air Races in October 1925 before being shipped to Brazil, where Fairchild used it for aerial survey work. At some point it was fitted with twin Lewis machine guns on a ring mount at the rear cockpit.