The flight controls of an aircraft are the essential systems that ensure aircraft stability, ease of coordinated flight, aerodynamic stability, and proper distribution of stresses related to flight. In order for a pilot nowadays with the more complex flight control systems to be confident in his or her safety and ability to fly the aircraft properly, a vast knowledge of how the flight control systems work is essential. In basic terms, the flight controls consist of anything that has to do with modifying the configuration of the aircraft in order to perform a manoeuvre.
Aircraft flight controls are activated through mechanical linkages in the cockpit flight controls that are attached to control wires, computer sensors, or connected directly to hydraulics. In the primary flight controls, you have the elevator control, aileron control, and rudder control. The aircraft’s elevator controls the pitch attitude, the ailerons control the aircraft’s bank, and the rudder controls the aircraft’s yaw(motion through the vertical axis). The secondary flight controls consist of things such as throttle, brakes, speed brakes/spoilers and flaps.
The primary flight controls are controlled through the cockpit by means of a control stick or control wheel. In smaller general aviation aircraft, these controls are activated by simply control wires that work through pulleys and simple mechanical systems with no automation whatsoever. These kinds of systems are very inexpensive, and make a world of sense to have in a small aircraft. It is ideal, because you get to feel exactly what is happening while you’re flying, and every feeling of force you get on the controls is real. In larger aircraft, these controls are automated by hydraulic systems directly connected to the flight controls, or by fly-by-wire systems. Fly-by-wire systems use computerized sensors to detect control movement, and they activate hydraulic actuators in the control surfaces. Many fly-by-wire systems nowadays also have force feedback that so when you are moving the controls, you get a sense of how much pressure is actually being forced on that control surface that you are moving.
The secondary flight controls are usually operated by means of a less complicated hydraulic or computerized systems. For example, the brakes. When you press down on the brakes in a small aircraft, you are simply pressing down on a hydraulic master cylinder that increases the pressure in the brakes lines, and clamps the brake calipers to the rotors. It is basically the same principle in larger aircraft, except a computer is measuring how far you are pushing down on the brakes, and determines how much hydraulic pressure to direct to the brake system. With the flaps in small airplanes, there is simply an electric motor that lowers the flaps. In larger aircraft which also have speed brakes and spoilers, these systems are controlled by a computer that senses what setting you have selected for the spoiler/flap deployment, and the hydraulic system will deploy for that setting. The landing gear is a fairly simple hydraulic system which operates in simply an “up or down” fashion.
