SIFT Army Aviation Information Practice Test

During a standard hover, the tail rotor primarily functions to counteract what force?

1. Torque effect

2. Gyroscopic precession

3. Weight distribution

4. Lift vectoring

The correct answer is: Torque effect

In a standard hover, the tail rotor's primary function is to counteract the torque effect generated by the main rotor. As the main rotor spins, it produces torque that tends to rotate the helicopter fuselage in the opposite direction. This is due to Newton's third law of motion, where every action has an equal and opposite reaction. The tail rotor creates a horizontal thrust that counterbalances this torque, allowing the helicopter to maintain a stable hover without unwanted yaw movement. Understanding the importance of the tail rotor in countering torque is crucial for safe helicopter operation, especially in maintaining directional control during hover. The other forces mentioned—such as gyroscopic precession, weight distribution, and lift vectoring—are also relevant to helicopter dynamics but do not specifically describe the primary function of the tail rotor during a hover. Gyroscopic precession refers to the effect of changes in rotor orientation on the helicopter's response, weight distribution pertains to how the helicopter is loaded, and lift vectoring involves changing the angle of lift to maneuver, but these do not directly explain the torque counteraction provided by the tail rotor.