Which of the following statements about the tail rotor system is correct?

• A. It lifts the aircraft
• B. It does not contribute to yaw control
• C. It powers the main rotor
• D. It provides anti-torque for the main rotor system

Answer: (D)

The tail rotor exists to counter the torque produced by turning the main rotor. When the engine drives the main rotor, the rotor’s torque tends to spin the helicopter’s fuselage in the opposite direction. The tail rotor pushes air in the opposite direction to create a thrust moment that cancels this torque, and pilots vary this thrust with the pedals to control the aircraft’s heading (yaw). It doesn’t lift the aircraft—lift comes from the main rotor—and it doesn’t power the main rotor; power flows from the engine to the main rotor through the drivetrain. So, the tail rotor’s role is to provide anti-torque for the main rotor system.