{{short description|Experimental Russian monoplane prototype from 1912}} {{Infobox aircraft | name = S-7 | logo = | logo_size = | image = Sikorsky S-7 aircraft front circa 1912.jpg | alt = | caption = Sikorsky S-7 circa 1912 | long_caption = | other_names = | aircraft_type = Experimental | aim = | outcome = | related = | national_origin = [[Russian Empire]] | manufacturer = [[Russo-Balt|Russian Baltic Railroad Car Works]] | design_group = | designer = Igor Sikorsky | builder = | issuer = | status = sold to [[Bulgarian Army]] for use in World War I | owners = | primary_user = | more_users = | service = | major_applications = | proposals = | prototypes = | number_built = 1 | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = | retired = | first_flight = July 1912 | initiated = | in_service = | last_flight = | expected = | developed_from = | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }} [[File:Sikorsky S-7 rear circa 1912.jpg|thumb|305px|S-7 view from aft]] The '''Sikorsky S-7''' was a Russian single engine experimental prototype aircraft built by the [[Russo-Balt|Russian Baltic Railroad Car Works]] shortly after [[Igor Sikorsky]] became chief engineer of the aircraft manufacturing division.

==Design and development== The S-7 was two-seater [[Flying wires|wire-braced]] [[monoplane]] powered by a {{convert|70|hp|kW|0|abbr=on}} [[Gnome et Rhône|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 [[Sikorsky S-6|S-6A]] including the main wing, tail and landing gear.<ref name=winged>{{cite book |last=Sikorsky |first=Igor|title=The Story of the Winged-S|year=1944|publisher=Dodd, Mead & Company|location=New York|isbn=9781258163556|page=43}}</ref>

==Operational history== 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]].<ref name=winged/>

==Specifications== {{Aircraft specs |ref=''Russian Aviation Museum''<ref name=ram>{{cite web|url=https://ram-home.com/ram-old/index.html|title=S-7|date=4 September 1997|website=ram-home.com|access-date=2 April 2017}}</ref>

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|crew=One |capacity=One passenger |length m=8.2 |length ft= |length in= |upper span m=10 |upper span ft= |upper span in= |upper span note= |lower span m= |lower span ft= |lower span in= |lower span note= |height m= |height ft= |height in= |wing area sqm=20 |wing area sqft= |wing area note= |aspect ratio= |airfoil= |empty weight kg=449 |empty weight lb= |empty weight note= |gross weight kg=776 |gross weight lb= |gross weight note= |fuel capacity= |more general= <!-- Powerplant --> |eng1 number=1 |eng1 name=[[Gnome Lambda]] |eng1 type=7-cylinder air-cooled rotary piston engine |eng1 kw= |eng1 hp=70

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==References== {{reflist}}

{{Sikorsky Aircraft}}

[[Category:Sikorsky aircraft|S-7]] [[Category:Single-engined tractor aircraft]] [[Category:Mid-wing aircraft]] [[Category:Aircraft first flown in 1912]] [[Category:Rotary-engined aircraft]]