Control Surfaces On An Aircraft And What They Do 

 

CONTROL SURFACES

A typical aircraft like the Vigilant has 3 major control surfaces. 

These are:-

Each has a PRIMARY EFFECT which are discussed below.

 

PRIMARY EFFECTS

Each of the control surfaces has a primary effect.

ELEVATOR - PITCH

AILERON - ROLL

RUDDER - YAW

So, what are these effects?

Pitch

The elevators make the aircraft pitch up or down.
The elevators are on the tail of the aircraft. If you raise the elevator the tail drops down and the plane pitches up and if you lower the elevator the tail comes up and the plane pitches down.

Roll

The ailerons make the aircraft roll
There is an aileron on the back edge of each wing. By moving the ailerons in opposite directions, the plane will roll.

Yaw

The rudder makes the aircraft yaw.
By moving the rudder to the right, the plane yaws the right and by moving the rudder to the left the plane yaws to the left.

 

 

SECONDARY EFFECTS OF CONTROLS

Two of the control surfaces have secondary effects. These are

 

AILERONS - YAW

RUDDER - ROLL

So, what are these secondary effects ?

 

Secondary Effect Of The Ailerons Explained

If the stick is moved to the left the aircraft will bank to the left. As the lift always acts at 90º to the wing, and weight always acts straight down, the resultant imbalance of forces causes the aircraft to sideslip to the left. Side slip. This sideslip causes a flow of air towards the fuselage sides. As there will be more area behind the Centre of Gravity than in front of it, the resultant force will tend to rotate the aircraft causing it to yaw.

 

Secondary Effect Of The Rudder Explained

Application of the rudder causes the aircraft to yaw from side to side. This yaw means that the wing on the outside of the turn is moving faster through the air, while the inside wing moves slower. This speed change generates more lift from the outside wing and less from the inner, causing the aircraft to roll in the direction of the turn. The application of rudder then, causes first a yaw, followed by a roll.

 

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