Definition
A small, vertically mounted rotor at the end of a single-rotor helicopter's tail boom that produces sideways thrust to counteract the torque created by the main rotor and to give the pilot directional (yaw) control around the vertical axis.
Plain English
The little spinning rotor on the tail of a helicopter. It pushes sideways to stop the helicopter from spinning the opposite way to its main rotor, and it lets the pilot point the nose left or right.
Context Anchor
Seen during helicopter preflight inspections, hover practice, takeoff, landing, and any discussion of pedal control.
Derivation
Rotor comes from the Latin word rota, meaning wheel. In aviation, a rotor is a set of blades that turns around a center point. Tail identifies its position at the rear of the helicopter.
Why Pilots Care
Loss of tail rotor effectiveness immediately removes yaw control and allows the fuselage to spin uncontrollably.
Intuition Check
Do not think of the tail rotor as a small lifting rotor for the tail. Its main job is to push sideways so the helicopter does not spin and the pilot can control the nose direction.
Example Sentence 1
During the hover check, the pilot pressed the left pedal and the tail rotor swung the nose smoothly to the left.
Example Sentence 2
During the hover taxi the student maintained heading with small tail rotor inputs.