The elevator – This forms part of the tailplane, being hinged to it. It is raised or lowered by a backward and forward movement of the stick. Some gliders have no fixed part to the tailplane and this arrangement is known as an all-flying tailplane; however the principle of operation is the same.
When the stick is moved backwards, the elevator rises and the airflow past them applies a downward force to it. This results in the tail of the aircraft falling in relation to the nose, or as it is usually thought of and seen by the pilot, in the nose rising in relation to the tail. Similarly, when the stick is moved forward the elevator is depressed and the nose goes down. The elevator thus causes a movement in the “pitching plane”, the aircraft pivoting about a lateral axis through its centre of gravity.
This pitching movement in flight alters the angle of attack of the wings to the airflow and the balance of forces is upset, causing the flight path to change.
Remember – No matter what the attitude of the aircraft is in relation to the ground, the controls always have the same primary effect on the aircraft (unless it is stalled). The ailerons give control in the rolling plane, the elevator in the pitching plane and the rudder in the yawing plane. These planes are referred to the aircraft and not to the earth.
The effect of a given control deflection depends upon the speed of the airflow over the control surfaces. At low speeds, larger control movements are necessary in order to produce the same effect on the aircraft.