As we are all aware, an aircraft in flight has six degrees of freedom. Three translational, that is, lateral, longitudinal and vertical and three rotational that is, rotation about the roll pitch and yaw axes. It is the actuation and control of the surfaces which cause rotation that will be discussed.

For the vast majority of aircraft, control in the three axes of rotation is achieved by three distinct movable surfaces which are elevators for pitch control, ailerons for roll control and rudder for yaw control. The effects of these controls are as follows—Fig. 1 the elevators will alter the angle of attack of the aircraft to the air and unless power is increased will result in a reduction in airspeed. If the airspeed is allowed to drop too much there will be a loss of lift on the wing and eventually a stall will occur. The ailerons will cause the aircraft to roll and alter the angle of bank. In so doing however the aircraft will begin to side slip, thus as there is more surface area aft of the cg than before it, the aircraft will turn.