The tail unit is the main part of the aircraft.
Vertical Horizontal 2 surfaces They are of symmetrical airfoil section
Each is divided into two parts The FRONT part is fixed. The REAR part is in the form of a flap which is operation providing directional control.
The vertical surface is called the “FIN”.
The horizontal surface is known as the “STABILISER”.
Both stabilisers are very similar to wing in construction. They are usually of all-metal construction of the cantilever type. They have two main members: spars and ribs to which metal skin is attached.
The vertical stabiliser or fin provides directional stability of the aeroplane in flight. It also serves as the base to which the rudder is attached.
The horizontal stabiliser provides longitudinal stability of the aeroplane in flight. It serves as a support for the elevators.