TsAGI 5-EA

Broadly similar to predecessors, incorporated new rotor proposed by I.P.Bratukhin with three large blades with articulated roots which provided lift, and three smaller blades with rigid attachment which provided control. Some accounts incorrectly state large and small rotors superimposed; all blades were in same plane, large and small alternating. This rotor worked, yet 5-EA appears not to have reached any considerable height or endurance (Western figures 13 miles and 1200 feet not confirmed in Soviet accounts). 5-EA flew from 1933 until late 1935 and was instrumental in providing research basis for machine with more powerful and more modern engine.

5-EA
Engine: 2 x M-2 piston, 120hp
Rotor diameter: 12.0m and 7.8m
Max take-off weight: 1210kg
Empty weight: 1047kg
Max speed: 20km/h
Ceiling: 40m
Endurance: 0.7h
Crew: 1