Helicopter Control Systems

M.K.MISHRA

• Helicopter, Lift is obtained by means of one or more power driven horizontal propellers which called Rotors.

• When the rotors of helicopter turns it produces lift and reaction torque, reaction torque which tends to make helicopter spin.

• Helicopters has a small rotor near the tail which called tail rotor compensates for reaction torque

• The direction of helicopter is controlled by inclining the axis of the main rotor path in that direction.

Function of Controls

• There are three major controls in the helicopter that the pilot must use during flight. They are :

( 1 ) Collective pitch control.

( 2 ) Anti Torque Pedals or Tail Rotor Control.

( 3 ) Cyclic Stick Control.

Collective Control

• he collective pitch lever or stick is located by the left side of the pilot's seat and is operated with the left hand

• The collective is used to increase main rotor pitch at all points of the rotor blade rotation

• It increases or decreases total rotor thrust

Anti-Torque Pedals or Tail Rotor Control

• In accordance with Newton's law of action and reaction, the helicopter fuselage tends to rotate in the direction opposite to the rotor blades.

• Compensation for torque in a single main rotor helicopter is accomplished by means of a variable pitch anti torque 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.