Flight Control Systems and Actuators Group 3

Types of Flight Control Systems Mechanical Hydraulic-Mechanical Fly-by-wire Other

Mechanical Flight Controls Common on General Aviation Aircraft Gives pilot a lot of “feel” as he is directly connected to the control surfaces on the aircraft Generally is made up of cables, pulleys, rods, and sometimes even chains Routing these kind of systems throughout the aircraft requires a lot of thought and creativity at times Generally not very good when there are large stick forces. The pilots strength becomes the limiting factor.

Hydraulic Mechanical Flight Controls Analogous to power steering on a car, easier physically to make control inputs but loss of “feel” can be a problem Sometimes referred to as “boosted” Adds complexity to an already complex system Added weight Has to include hydraulic lines, actuators, pumps, and a linkage between the hydraulic system and the mechanical cockpit controls Makes flying the aircraft less demanding and allows for high loads on control surfaces and much physically larger control surfaces Sometimes makes use of “Artificial Feel Devices”

Fly By Wire Really more of a subset of Hydraulic Controls Commonly uses a hydraulic control circuit to physically move the control surfaces and a computer controlled (digital) circuit that takes pilot input and actuates the hydraulic system Common on newer commercial and military aircraft Computer “interpretation” of pilot input allows for better stability of the aircraft allowing much more “on the edge” designs to be capable of flying Has to be redundant because the computer is the only path between the pilot and the controls

Other Flight Controls Electrically actuated flight controls which uses electric motors to move control surfaces, still an emerging technology Warping uses piezoelectric materials to warp the wings of an aircraft Closed circuit hydraulic controls, each individual control surface has its own full hydraulic system, eliminates a central system Intelligent flight controls, uses neural networks to determine changes in flight dynamics and adjust control laws accordingly