The tail rotor primarily serves what purpose on a helicopter?

• A. Lift
• B. Anti-Torque
• C. Propulsion
• D. Stability during Hover

Answer: (B)

The main idea is that the tail rotor provides anti-torque to counter the twisting effect of the main rotor. In a single-rotor helicopter, the engine turns the large rotor, and by Newton’s third law the fuselage tends to spin in the opposite direction. The tail rotor pushes or pulls on the air to create a counteracting torque, keeping the helicopter from spinning and giving the pilot control of yaw by adjusting how much tail rotor thrust is produced. Lift and propulsion come from the main rotor and the drive system, respectively, while hover stability is achieved through this anti-torque action plus pilot input. In short, the tail rotor’s job is to cancel the main rotor’s torque so the aircraft can be steered and held steady.