Bratukhin Omega II
Also designated 2MG (twin-engined helicopter), the Omega project was authorised on 27 June 1940 with two engine rotor groups side-by-side and steel-tube construction with fabric covering. Lateral structures carrying engine rotor units and fixed main landing gears were triangular spaceframes with two lower booms and one at top, with no covering. Fully articulated hubs of steel and light-alloy, carrying three duralumin blades, rotors being handed to rotate in opposite directions. Each rotor was driven by separate MV-6 engine linked with synchronizing shaft with universal joint on aircraft centreline. This shaft provided also opportunity to fly helicopter with any one of engines running. Engines of Omega were equipped with specially designed gearboxes, clutch and other elements. Manual controls, driving swash-plates in fixed and rotating parts of head for collective and cyclic pitch control. Much research into optimum method with differential collective to apply initial bank and then T-tail rudder, worked by pedals, to make turns. Emergency control for immediately autorotative setting of both rotors. Final 0.231 gearbox to rotors (577 rpm). No centrifugal clutches. Three mechanical clutches, with overrunning capability, engaged by observer after both engines were running. First drive to associated rotor was clutched-in; then interlink left/right shaft. Fuel tanks behind engines. Observer behind pilot.
The Omega II, sometimes called G-2 (helicopter 2), was the original design with superior engines in streamlined pods with fan-assisted cooling. Gearboxes, clutches, cooling system etc were redesigned. Drive ratio 0.32. Important progress was made in optimization of gearbox ratio. It resulted in increase of the rotor lift force by 300kg and substantial increase of ceiling.
The Omega II performed in the 1948 Soviet Aviation Day Display at Tushino.
Engine: 2x750 h.p. Ash-21
Rotors: 2 x 3-blade main rotors on outriggers.