Which unit is used on a helicopter to compensate for torque created by the main rotor?

The tail rotor is the unit used on a helicopter to compensate for the torque created by the main rotor. When the main rotor spins, it generates torque that can cause the body of the helicopter to rotate in the opposite direction. This is known as the "reactive torque." To counteract this effect, helicopters are equipped with a tail rotor that produces thrust in the opposite direction of the torque. By adjusting the pitch of the blades on the tail rotor, pilots can control the helicopter's yaw, allowing for stable flight and directional control.

The main rotor is responsible for generating lift and does not compensate for torque. The collective and cyclic controls are pilot inputs used to change the pitch of the blades on the main rotor to adjust lift and directional movement but do not directly counteract the torque produced by the rotor system. Therefore, the tail rotor plays a crucial role in maintaining stability and control in a helicopter's flight dynamics by neutralizing the torque generated by the main rotor.