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

irst 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.
  • "History of aircraft construction in the USSR" by V.B.Shavrov, Vol.1 p.94;
  • 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 33kg/m2
    Power load 10kg/hp
    Maximum Speed less than 100km/h
    Modified September 2, 1997
    by Alexandre Savine;
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