Directional control systems provide a means of controlling and stabilizing the aircraft about its vertical axis. Most aircraft use conventional rudder control systems for this purpose. The rudder control system is operated by the rudder pedals in the cockpit, and is powered hydraulically through the power mechanism. In the event of hydraulic power failure, the hydraulic portion of the system is bypassed, and the system is powered mechanically through control cables and linkage. When the pilot depresses the rudder pedals, the control cables move a cable sector assembly. The cable sector, through a push-pull tube and linkage, actuates the power mechanism and causes deflection of the rudder to the left or right.

The F-14 flight control systems include the rudder, the stabilizer, and the spoiler control systems; the wing surfaces control system; the angle-of-attack system; and the speed brake control system. Because of the complexity of the F-14 flight control systems, only a brief description is presented.

RUDDER CONTROL (YAW AXIS). -Rudder control, which affects the yaw axis, is provided by way of the rudder pedals. Rudder pedal movement is mechanically transferred to the left and right rudder servo cylinders by the rudder feel assembly, the yaw summing network, and a reversing network.

SPOILER CONTROL (LATERAL AXIS). -Spoiler control is provided through the control stick grip, roll command transducer, roll computer, pitch computer, and eight spoiler actuators (one per spoiler). The spoilers, when used to increase the effect of roll-axis control can only be controlled when the wings are swept forward of 57 degrees. Right or left movement of the control stick grip is mechanically transferred to the roll command transducer, which converts the movement to inboard and outboard spoiler roll commands.

DIRECT LIFT CONTROL (DLC). -DLC moves the spoilers and horizontal stabilizers to increase aircraft vertical descent rate during landings without changing engine power.

WING SURFACE CONTROL SYSTEM. -The wing surface control system controls the variable-geometry wings to maximize aircraft performance at all speeds and altitudes. The system also provides high lift and drag forces for takeoff and landing, and increased lift for slow speeds. At supersonic speeds, the system produces aerodynamic lift to reduce trim drag. The wing sweep control, initiated at the throttle quadrant, provides electronic or mechanical control of a hydromechanical system that sweeps the wings. See figure 1-7. The wings can be swept from 20 degrees through 68 degrees in flight. On the ground, mechanical control allows awing sweep position of 75 degrees. See figure 1-8. This position is used when flight deck personnel spot the aircraft or when maintenance personnel need to enable the wing sweep control self-test.

Electronic Control. -Wing sweep using electronic control is initiated at the throttle quadrant. Four modes are available: automatic, aft manual, forward manual, or bomb manual. Selection of these modes causes the air data computer to generate wing sweep commands consistent with the aircrafts speed, altitude, and configuration of the flaps and slats. If the automatic mode is used to apply the commands, the wings are positioned at a rate of 7.5 degrees per second.

Mechanical Control. -When wing sweep is in the mechanical control mode, the wing sweep handle uses the wing sweep/flap and slat control box to position the wings. Because minimum wing sweep limiting is not available in the mechanical control mode, the wings can be swept to an adverse position that could cause damage to the wings. Mechanical control is used for emergency wing sweep and wing oversweep.