Flight control surfaces

Flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude. The primary function of these is to control the aircraft's movement along the three axes of rotation. Flight control surfaces are generally operated by dedicated aircraft flight control systems.

Development of an effective set of flight control surfaces was a critical advance in the history of development of aircraft. Early efforts at fixed-wing aircraft design succeeded in generating sufficient lift to get the aircraft off the ground, however with limited control. The development of effective flight controls allowed stable flight.

A conventional fixed-wing aircraft uses three primary flight control surfaces– aileron, rudder and elevator to control the roll, yaw, and pitch respectively. Secondary flight control surfaces might include spoiler, flaps, and slats on the wings. The main control surfaces of a fixed-wing aircraft are attached to the airframe in such a way that they can perform the intended range of motion. These usually work by deflecting the air stream passing over them, to create the intended effect.

Certain fixed-wing aircraft configurations may use different control surfaces however the basic principles remain. For other airborne vehicles, these vary depending on the controls required. For rotary wing aircraft such as a helicopter, the stick and the rudder is used to accomplish the same motions about the three principal axes and the rotating flight controls such as main rotor and tail rotor disks. Certain elements are considered as a generalized fluid control surface, such as the rudders, which are shared between aircraft and watercraft.