What best describes autorotation?

What best describes autorotation?

• A. The main rotor is driven by relative wind only
• B. Engine power is supplied to the rotor to maintain RPM
• C. Electrical power powers the rotor
• D. Tail rotor thrust powers the main rotor

Answer: (A)

Autorotation is when the main rotor stays turning not because the engine is driving it, but because the air moving through the rotor system from the descent provides the energy to keep the blades turning. If the engine fails or is disengaged, the rotor is effectively free to rotate, and the upward flow of air through the rotor disc—generated by the helicopter's descent—drives the blades. The pilot then uses control inputs to manage the rotor speed and descent rate so that energy stored in the rotor can be converted to a controlled landing. Electrical power or tail-rotor thrust do not power the main rotor in this condition, and engine power is not delivering rotor rotation during autorotation.

Autorotation is when the main rotor stays turning not because the engine is driving it, but because the air moving through the rotor system from the descent provides the energy to keep the blades turning. If the engine fails or is disengaged, the rotor is effectively free to rotate, and the upward flow of air through the rotor disc—generated by the helicopter's descent—drives the blades. The pilot then uses control inputs to manage the rotor speed and descent rate so that energy stored in the rotor can be converted to a controlled landing. Electrical power or tail-rotor thrust do not power the main rotor in this condition, and engine power is not delivering rotor rotation during autorotation.