Which mechanism provides anti-torque on a helicopter?

• A. Vertical stabilizer
• B. Rudder on the vertical tail
• C. Skids
• D. Tail (anti-torque) rotor

Answer: (D)

When the main rotor spins, the engine tries to turn the fuselage in the opposite direction. To prevent the helicopter from spinning, an anti-torque device is used. In most helicopters, a small tail rotor mounted on the tail provides thrust opposite to the main rotor’s torque. By adjusting the tail rotor’s pitch with the anti-torque pedals, the pilot can balance the torque and control yaw, keeping the helicopter headed where intended. The tail rotor is the active means of countering torque; the vertical stabilizer is just a fixed surface for stability, a rudder on the tail isn’t the primary anti-torque in this setup, and skids are only for landing gear. Some designs use alternative systems, but the classic anti-torque mechanism is the tail rotor.