Understanding the aerodynamics and control surfaces of an aeroplane

Here, you can get a quick understanding of roll, pitch & yaw, aileron, rudder etc.

Sometimes I wonder how do aeroplanes move up, down, left, right without the presence of any solid contact with the surrounding in air. No tyres, no roads, no steering, but still aeroplanes travel from one place to another. This curiosity made be research on this topic and I came across the aerodynamics fundamentals of an aeroplane. Before coming on to the aerodynamics, let discuss the actuators which are helpful in governing these motions. These actuators are known as control surfaces

Control surfaces : These are the actuators which are nothing but the moving parts on the outer surface of the aeroplane. These surfaces are helpful in achieving desired motion e.g. lift, roll, pitch etc. There are mainly three types of control surfaces on the aeroplane, which are as follows :

Ailerons : An aileron (French for ‘little wing’) is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around the aircraft’s longitudinal axis), which normally results in a change in flight path due to the tilting of the lift vector. Movement around this axis is called ‘rolling’ or ‘banking’.



Rudder : A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other conveyance that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane. A rudder operates by redirecting the fluid past the hull (watercraft) or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft’s stern, tail, or after end. Often rudders are shaped so as to minimize hydrodynamic or aerodynamic drag.


Elevators : Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft’s pitch, and therefore the angle of attack and the lift of the wing. The elevators are usually hinged to the tailplane or horizontal stabilizer. They may be the only pitch control surface present, sometimes located at front (early airplanes) or integrated into a rear “all-moving tailplane” also called a slab elevator or stabilator.


Now, we can talk about the basic motions of the aircraft. The information about basic motions like roll/ pitch/ yaw can be found here. These fundamental motions of aircraft are governed by these control surfaces only.

Ailerons are used to obtain roll motion. If left aileron up and right aileron down gives to clockwise rotation of the aeroplanes, then the reverse can be achieved by left aileron down and right aileron up.
Rudder is used to provide yaw motion to the aircraft. If rudder is pulled to left direction, the nose of the aircraft moves to left, and reverse motion is achieved by pulling the rudder to right direction.
Elevators are used for controlling pitch of the aircraft. If the elevators are pulled upside, then the nose of the aeroplanes moves up, and it moves down if the elevators are pushed down.

Note: It is very difficult to achieve independant roll or pitch or yaw motion due to stability. Thus, these motions occur in pairs generally e.g. in order to move the aircraft to right direction, positive yaw is acquired along with slight clockwise roll.

Hope you have a better understanding of control surfaces now.