Actuation systems for flight control

EE 48 November 1986 ACTUATION SYSTEMS FOR FLIGHT CONTROL The need to transmit con- trol of an aircraft from the pilot"s hands to the flight control surfaces has always existed. In early aircraft, this was achieved by rudimentary linkages consisting of rods and cables, but as speeds in- creased it became necessary to boost the pilot"s muscular effort by the introduction of hydraulic systems. These were effectively fluid rods: the fluid being, to all intents and purposes, in- compressible. When such systems were introduced just before World War II, it was felt that hydraulic ac- tuators enjoyed many ad- vantages over the electromechanical kind in terms of reliability and the high torque and power they could provide. Consequently they became recognized in the ensuing 20 to 30 years as the preferred method for all high power demand applications. Hydraulic systems were used to con- trol and operate flaps and slats, tailplanes, elevators, ailerons, rudder surfaces, and various engine fu...