The evolution of flight control

All aircraft are governed by the same basic principles of flight control, whether the vehicle is the most sophisticated high-performance fighter or the simplest model aircraft.

Flight control includes control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control the aircraft’s direction in flight. Aircraft engine controls are also considered as flight controls as they change the operating speed.

Flight controls have gone through a long process of evolution that has lead to different configurations. These configurations depend upon the moment of history, type of aircraft and mission. Three main categories can be described for aircraft controls:

Mechanical configurations

These are the most elementary design of a flight control systems. This kind of flight control system was used in early aircraft and is still used in current light aircraft, like the Cessna Skyhawk.

Mechanical control systems were limited to small aircraft because, for larger configurations, the loads acting over the control surfaces are far larger for a pilot to control it properly.

To bypass this limitation, levers and pulleys were implemented (take the Fokker 50 as an example). Other alternative was implemented in the Boeing 707. It consisted in using servo tabs to reduce the required control force exerted by the pilot by exploiting the aerodynamic forces which act on the tabs themselves.