Technical data
Type	S-9 'Kruglyj'
Function	Experimental
Year	1913
Crew	3
Engines	1*100hp Gnome Monosaupape
Wing Span	12.0m
Wing Area	30.0m²
Empty weight	690kg
Loaded weight	990kg
Wing Load (kg/m²)	33
Power load (kg/hp)	10
Maximum Speed	less than 100km/h

S-9 'Kruglyj' (The Rounded One), I.I.Sikorsky

(48k b/w)"History of aircraft construction in the USSR", Vol.1 p.92;

First monocoque monoplane built in Russia. Plywood skin thickness was 5mm on nose section and 3mm on the tail. Rectangular wings had aerodynamically clean joints with fuselage. Despite advanced design, aircraft was overweight and almost all dimensions were larger than in the project. In addition the engine provided only 80% of its nominal power. All this resulted in quite poor performance, and after few test flights S-9 was abandoned.

Sources:

"History of aircraft construction in the USSR", Vol.1 p.94;