HELICOPTER OPERATION

In a helicopter flight characteristics are determined by the rotational speed and pitch variations of the rotor blades. Since its flight characteristics are independent of forward speed, a helicopter is able to move in any direction at a controlled low speed and still remains safely airborne.

Many factors determine the amount of lift available in helicopter operation. Generally speaking, the pilot has control of two of these. One is the pitch angle of the rotor blades; the other is the power delivered to the rotor. By controlling the pitch angle of the rotor blades, the pilot can establish the vertical flight of the helicopter. By manipulating the engine speed, the pilot maintains the desired amount of lift of the aircraft regardless of the increase or decrease in blade pitch.

The cyclic pitch control is similar to the control stick of a conventional aircraft. It acts through a mechanical linkage to cause the pitch of each main rotor blade to change during a cycle of rotation. The rapidly rotating rotor blades create a disk area that can be tilted in any direction with respect to the supporting rotor mast. Horizontal flight is controlled by changing the direction of tilt of the rotor disk to produce a force in the desired direction.