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Why do Russian helicopters have 2 rotors?
Having two coaxial sets of rotors provides symmetry of forces around the central axis for lifting the vehicle and laterally when flying in any direction. Because of the mechanical complexity, many helicopter designs use alternate configurations to avoid problems that arise when only one main rotor is used.
What are the advantages of contra-rotating propellers?
Use of contra-rotating propellers recovers energy lost due to the motion of the air in the slipstream of the forward propeller and allows for an increase in power without a corresponding increase in propeller diameter. It will also help counter the torque effects of a high power piston engine.
What is the benefit of contra-rotating propellers?
What are some characteristics of contra rotating helicopters?
Contra-rotating helicopters do not need tail rotor to counteract the torque—the force that tends to rotate the body of helicopter in a direction opposite to rotor blades. Absence of a tail rotor saves sizable engine power. Contra-rotating helicopters are, therefore, more powerful, compact and maneuverable than traditional helicopters.
Can a helicopter rotor be tilted for cyclic control?
Counter-rotating rotors on a helicopter would neutralize the reaction torque into the airframe. So yes for a very small helicopter, it should be possible to tilt the main rotor for cyclic control, without hydraulic power assist. If one is going to use a swashplate for collective control, it is easier to just control cyclic conventionally.
How are the rotors on a Sikorsky helicopter different?
One of Sikorsky’s later designs uses a co-axial rotor (one above the other on the same mast, rotating in opposite directions). This way, as one rotor’s advancing side is the other rotor’s retreating side.
How does an autogyro work in a helicopter?
Most autogyros tilt the entire rotor for cyclic control. Some autogyros apply engine torque to the main rotor to assist in achieving short takeoffs. Now for this brief time, the autogyro is functioning like a helicopter, and the main rotor is driven by the engine prior to takeoff.