The S-35 was designed as a twin-engined transport with a range of about 1600km.
In the spring of 1926 Capt. Rene Fonck, a French First World War fighter ace, persuaded Sikorsky to redesign it in an attempt to win the $25,000 Orteig prize for the first non-stop New York-Paris flight. It became a very different aircraft, with three 400hp Gnome-Rhone Jupiter engines and vastly increased fuel load. The first test flight, by Fonck and Igor Sikorsky, was made on 23 August 1926. Later, pilot Frank LaVista of the Department of Commerce reported that the aircraft handled very well, could climb on two engines, and lost only 15m of height while flying at 132km/h for 35 seconds on one engine.
Jettisonable auxiliary landing gear was fitted to the S-35 for take-off on its transatlantic attempt, at an overload weight of 8400kg, on 20 September 1926. Fonck insisted on having a radio operator, Charles Clavier, and veteran Sikorsky mechanic Jacob Islamoff, in addition to his co-pilot Lt Lawrence Curtin of the US Navy. Watched by a huge crowd, part of the auxiliary landing gear broke away as the aircraft gathered speed. It plunged down a steep slope beyond the runway and burst into flames. Only the two pilots escaped. The S-35, which had cost $100,000 to build, was destroyed.