What is the degree change in direction provided by the tail rotor gearbox?

• A. 70, reduces
• B. 70, increases
• C. 90, reduces
• D. 90, increases

Answer: (C)

The tail rotor gearbox on a helicopter is designed to change the direction of the power output from the main rotor system. In this case, it typically provides a 90-degree change in direction. This directional change is crucial because it allows the tail rotor to generate thrust that counters the torque produced by the main rotor, enabling the helicopter to maintain stability and control during flight.

The function of the tail rotor is to provide the necessary yaw control – it helps the pilot turn the helicopter left or right. By changing the direction of the rotor thrust, the tail rotor can effectively counteract the rotational force that the main rotor imparts on the entire aircraft structure.

The specific phrasing “reduces” in the correct choice aligns with the concept of translating rotational motion into linear thrust in a manner that aids in stabilizing the aircraft, rather than increasing the action of the system. This understanding of how the tail rotor gearbox facilitates control indicates that the primary intention is to reduce unwanted rotational movement, affirming the critical role of this component in helicopter operation.