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How does autorotation work on a helicopter?
Autorotation is a state of flight in which the main rotor system of a helicopter or similar aircraft turns by the action of air moving up through the rotor, as with an autogyro, rather than engine power driving the rotor. It is analogous to gliding flight in a fixed-wing aircraft.
What is autorotation in a spin?
For fixed-wing aircraft, autorotation is the tendency of an aircraft in or near a stall to roll spontaneously to the right or left, leading to a spin (a state of continuous autorotation).
Does the tail rotor is required in autorotation?
The most common reason for an autorotation is failure of the engine or drive line, but autorotation may also be performed in the event of a complete tail rotor failure, since there is virtually no torque produced in an autorotation.
Why does a helicopter yaw during autorotation?
Essentially, the pilot is consuming the energy stored in the aircraft’s altitude to maintain rotor rpm. Generally, this will result in a 1,500-foot-per-minute descent. While this is happening, the loss of engine torque will cause the helicopter to yaw severely to the left because the tail rotor is still producing thrust.
How does the rotor system work in autorotation?
To fully understand how autorotation works, we need to review some basic aerodynamics. The rotor blades spin to produce airflow and consequently lift and drag. The rotational speed of the rotor system is held constant, and lift is created by increasing each rotor blade’s angle of attack.
How is lift created in an autorotation system?
The rotational speed of the rotor system is held constant, and lift is created by increasing each rotor blade’s angle of attack. This is accomplished by raising the collective pitch control in the cockpit. Basic aerodynamic theory tells us that an increase in lift will be accompanied by an increase in drag.
What makes the tail rotor spin faster than the main rotor?
Gearing allows it to spin faster than the main rotor, and its rpm varies in direct relation to main rotor rpm. To rotate the fuselage around the main rotor axis, the pilot changes the tail rotor blades’ angle of attack, and hence thrust, with anti-torque pedals in the cockpit.