Flight Controls

example, when the control wheel, or control stick, is moved to produce a left roll, the interconnect cable and spring pulls forward on the left rudder pedal just enough to prevent the nose of the aircraft from yawing to the right. The force applied to the rudder by the springs can be overridden if it becomes necessary to slip the aircraft. [Figure 6-8] Flaperons Flaperons combine both aspects of flaps and ailerons. In addition to controlling the bank angle of an aircraft like conventional ailerons, flaperons can be lowered together to function much the same as a dedicated set of flaps. The Figure 6-9. Flaperons on a Skystar Kitfox MK 7. pilot retains separate controls for ailerons and flaps. A mixer is used to combine the separate pilot inputs into this single linkages. Aft movement of the control column deflects set of control surfaces called flaperons. Many designs that the trailing edge of the elevator surface up. This is usually incorporate flaperons mount the control surfaces away from referred to as the up-elevator position. [Figure 6-10] the wing to provide undisturbed airflow at high angles of attack and/or low airspeeds. [Figure 6-9] The up-elevator position decreases the camber of the elevator and creates a downward aerodynamic force, which is greater Elevator than the normal tail-down force that exists in straight-and- The elevator controls pitch about the lateral axis. Like the level flight. The overall effect causes the tail of the aircraft ailerons on small aircraft, the elevator is connected to the to move down and the nose to pitch up. The pitching moment control column in the flight deck by a series of mechanical occurs about the center of gravity (CG). The strength of the pitching moment is determined by the distance between the CG and the horizontal tail surface, as well as by the Rudder deflects with ailerons aerodynamic effectiveness of the horizontal tail surface. Moving the control column forward has the opposite effect. In this case, elevator camber increases, creating more lift (less tail-down force) on the horizontal stabilizer/elevator. This moves the tail upward and pitches the nose down. Again, the pitching moment occurs about the CG. As mentioned earlier, stability, power, thrustline, and the position of the horizontal tail surfaces on the empennage are factors in elevator effectiveness controlling pitch. For Contro a l f c t olumn n w o d Up elevator lia T CG N o s e u p Downward aerodynamic force Rudder/Aileron interconnecting springs Figure 6-10. The elevator is the primary control for changing the Figure 6-8. Coupled ailerons and rudder. pitch attitude of an aircraft. 6-5