User Guide

Flying Controls of a Helicopter
Three controls are used to fly a helicopter; the collective lever, the cyclic stick, and the yaw
pedals [diagram 6.6]. Each has a Primary (main) and a Secondary (side) effect.
Collective Lever:
This is mounted on the left side of the seat, and pivots up and down about its back
end, like the handbrake on most European cars. It is used with the left hand, and has a
friction clamp so that when you take your hand off, it stays in the position where you left it.
The three phrases commonly used to describe what you can do with it are ‘raising the
collective’, ‘lowering the collective’, and ‘bottoming the collective’. All three are simple,
literal descriptions.
When you raise the collective, you are increasing the angle of attack of all the main rotor
blades by the same amount, so that the rotor generates more thrust. Lowering the collective
has the opposite effect. Bottoming the collective reduces main rotor thrust to effectively
nothing. If you were hovering, raising the collective would cause the helicopter to climb
straight up, lowering the collective would cause the helicopter to descend. This is the
primary effect of the collective control.
The secondary effect of the collective is due to the fact that it takes more power to drive the
rotor through the air at a high angle of attack than at a low one. In older (or simpler)
helicopters, the pilot has to use a twist-grip on the collective lever to add or reduce power.
More sophisticated modern helicopters do this automatically. In either case, because the
engine must develop more or less power, the main rotor torque effect becomes larger or
GROUND SCHOOL
5
Diagram 6.5: Rolling moment with airflow across rotor disc