S-7
Sikorsky S-7 circa 1912
Role	Experimental Type of aircraft
National origin	Russian Empire
Manufacturer	Russian Baltic Railroad Car Works
Designer	Igor Sikorsky
First flight	July 1912
Status	sold to Bulgarian Army for use in World War I
Number built	1

The Sikorsky S-7 was a Russian single engine experimental prototype aircraft built by the Russian Baltic Railroad Car Works shortly after Igor Sikorsky became chief engineer of the aircraft manufacturing division.

The S-7 was two-seater wire-braced monoplane powered by a 70 hp (52 kW) Gnome air-cooled rotary engine. Construction began in early summer of 1912 and completed in July. The pilot sat in the rear cockpit with a passenger seated in a forward compartment in a tandem arrangement. The fuselage was enclosed in plywood and the aircraft used components taken from the S-6A including the main wing, tail and landing gear.^[1]

The S-7 was entered in the international military competition at Saint Petersburg in August 1912. During a take-off attempt from a furrowed field the landing gear was severely damaged and the S-7 was unable to finish the completion. In 1913 the aircraft was repaired and served as a trainer. In 1914 Bulgaria purchased the S-7 and used it in operations during World War I.^[1]

Data from Russian Aviation Museum^[2]

General characteristics

• Crew: One
• Capacity: One passenger
• Length: 26 ft 11 in (8.2 m)
• Upper wingspan: 32 ft 10 in (10 m)
• Wing area: 220 sq ft (20 m²)
• Empty weight: 990 lb (449 kg)
• Gross weight: 1,711 lb (776 kg)
• Powerplant: 1 × Gnome Lambda 7-cylinder air-cooled rotary piston engine, 70 hp (52 kW)

Performance

• Maximum speed: 67 mph (108 km/h, 58 kn)