In accordance with Newton's law of action and reaction, the helicopter fuselage tends to rotate in the direction opposite
to the rotor blades . This effect is called torque . Torque must be counteracted and controlled to make flight is possible .
Compensation for torque in a single main rotor helicopter is accomplished by means of a variable pitch antitorque rotor (tail rotor)
located on the end of the tail boom extension at the rear of fuselage.
Heading Control : In addition to counteracted torque, the tail rotor and its control linkage also permit control of the helicopter heading
during flight . Application of more control than is necessary to counteract torque will cause the nose of helicopter to turn in the
direction of pedal movement.
In forward flight , the pedals are not used to control the heading of the helicopter (except during portions of crosswind takeoff and approach).
They are used to compensate for torque to put the helicopter in longitudinal trim so that coordinated flight can be maintained.
The thrust of the tail rotor is depend upon the pitch angle of the tail rotor blades. The tail rotor may have a positive pitch angle or it may have a negative pitch angle which
to push the tail to the right or pull the tail to the left.
With the right pedal pressed or moved forward of the neutral position will cause the tail rotor blades to change the pitch angle and the nose of helicopter will yaw to the right .
With the left pedal pressed or moved forward of the neutral position will cause the tail rotor blades to change the pitch angle opposite to the right pedal and
the nose of helicopter will yaw to the left.