Principles of Flight - Secondary Flight Controls (1)

Apart from aileron, elevator and rudder, there are also secondary flight controls which help with different maneuvers and improve performance.

Secondary flight controls include high- lift devices e.g. flaps, fixed slots, movable slats and leading edge flaps ; and high-drag devices e.g spoilers. 

Flaps

It attaches to the trailing edge of the wing. It increases the lift coefficient (CL) by increasing the curvature of the wing. 

By referring to the Lift Equation :

With the application of flap, the CL is increased. It allows the aircraft to maintain the same amount of lift (L) but at a lower speed (v) without leading to a stall.

Slots, Slats, Leading Edge Flaps

Slots help delay the separation of boundary layer. Slat and leading edge flaps extend from the leading edge. It improves lift-generating ability by changing the curvature and chord line of the wing.

Spoilers

It is a high-drag device. It reduces lift and increases drag by disturbing the airflow on the upper wing.