H.Nowarra, G.Duval Russian Civil and Military Aircraft 1884-1969

Sikorski’s next design, the S.6, was to some extent inspired by the French Caudron G.2 and G.3. Three versions of this biplane were built, the first as a three-seater, with the pilot sitting behind two passengers, the others as two-seaters. Of these, the S.6 and S.6B were completed as landplanes, while the S.6A was a floatplane, all three machines being ready for testing in 1912, fitted with the 100 h.p. Argus engine. Speeds of 70 m.p.h., 77 m.p.h. and 71 m.p.h. respectively were claimed, although the officially stated speed of the S.6A seems rather improbable, using as it did the same power unit as the other two, and yet having the considerable drag of the floats to overcome.

A.Durkota, T.Darcey, V.Kulikov The Imperial Russian Air Service (Flying Machines)

Igor Ivanovich Sikorsky

Sikorsky S-6A

  Although the two aircraft looked nothing alike, the S-6A was basically a redesigned S-6. The most important design change was the elimination of the tail boom, which was replaced with a fuselage covered with thin plywood (0.125 inches thick). To reduce drag, the radiator was placed underneath the fuselage, the wing struts were streamlined, and the lower-wing ailerons were removed.
  On its first test flights in early March, the S-6A's performance exceeded the most optimistic predictions. Takeoff and landing runs were shorter, and rate of climb was improved with significantly higher payloads. Depending on fuel load and number of passengers aboard, speed ranged from 68 to 75 mph while carrying loads of up to 1,000 pounds. On March 14, Sikorsky established a new world's speed record with 2 passengers (3 men on board) when he attained a speed of 65.8 mph.
  In April 1912, the S-6A was shown at the Moscow Aeronautical Exhibition, winning Sikorsky top prize - the "Great Golden Medal" for achievement in aviation.


The Russian Baltic Railroad Car Factory (R-BVZ)

  With the success of the S-6A, Sikorsky received numerous offers of employment In the spring of 1912, he completed negotiations with the Russian Baltic Railroad Car Factory (Russko-Baltiisky Vagonny Zaved or R-BVZ), and entered what many consider the second phase of his aviation career.
  The company obtained exclusive design rights for the S-6A and any subsequent designs for a period of five years. Sikorsky received the position of "designer and chief engineer of the company's aircraft factory," salary, royalties, and the right to build not less than one experimental airplane every year. He would later write, "Looking backward at that time, I realized to what a considerable extent this success was due to the support and encouragement which I always received from members of my family. I must also mention the fine cooperation and honest, hard work that was always done by the small group of men who worked with me during the three years. The six men who formed my permanent staff."
  In late spring, 1912, Sikorsky shipped the S-6A by train to St. Petersburg. There he and his staff of six men went to work in a factory rented by the RBVZ. At his new job Sikorsky immediately started to design new aircraft for the Russian War Department's International Aircraft Competition.


Sikorsky S-6B

  In layout, dimensions, and structure the S-6B was only slightly different from the S-6A. The most noticeable difference was the half-round fairing on the top of the fuselage which separated the two cockpits. The landing gear had two axles and supported four wheels. Powered by a 100hp Argus engine, the S-6B obtained a top speed of 70.4 mph with a load of 721 pounds. With the S-6B, Sikorsky made his first night flight from the Komandantsky Airfield.
  Sikorsky finished the S-6B in July 1912. He entered it in the Russian Military's International Aviation Competition of 1912, and won first place - a prize of 30,000 Rubles. Sikorsky split the prize money with the RBVZ administration. His share enabled him to repay his family and, it is said, to purchase his first automobile.



Sikorsky Aircraft Data
Model: S-1 S-2 S-3 S-4 S-5 S-6 S-6A
Year: 1910 1910 1910 1910 1911 1911 1912
Engine(s) type: 15hp Anzani 25hp Anzani 35hp Anzani 50hp Anzani 50hp Argus 100hp Argus 100hp Argus
Length, m: 8 8 8 8 8.5 8.8 9.2
Wing Span; m: top/bottom 8 8 8 8 12/9 11.8 14.5/11.7
Wing Area, m2: 24 24 24 24 33 35.4 39
Wt. empty, kg: 180 190 220 260 320 650 650
Wt. fuel/oil, kg: 10 10 20 30 40 60 60
Wt. load, kg: 70 70 90 100 120 340 450
Wt. flying, kg: 250 260 310 360 440 990 1100
Wingload, kg/m2: 10.4 10.8 13 12.9 13.3 24 23
Powerload, kg/hp: 16 10.2 8.9 7.2 8.8 8.5 9

Model: S-6B S-7 S-8 S-9 S-5A (twin float) S-5A (single float) S-10 (competition)
Year: 1912 1912 1912 1913 1912 1912 1913
Engine(s) type: 100hp Argus 70hp Gnome 50hp Gnome 100hp Gnome(1) 60hp Gnome 80hp Gnome 80hp Gnome
Length, m: 8.5 8.2 7.5 - 8 8 8
Wing Span, m: top/bottom 14.9/10.9 10 12/8 12 12/8.5 12/8.5 16.9/12
Wing Area, m2: 37.5 20 27 30 30 30 46
Wt. empty, kg: 590 449 - 690 - - 567
Wt. load, kg: 327 327 - 300 - - 444
Wt. flying, kg: 917 776 - 990 - - 1011
Wingload, kg/m2: 10.4 10.8 13 12.9 - - 22
Powerload, kg/hp: 16 10.2 8.9 7.2 - - 12.7
Speed, km/h: - - - - - - 99
Notes:
1. Gnome Monosoupape.