22.16.7. Ailerons & Elevons

Reference:  Abbott, Richard. Analysis and Design of Composite and Metallic Flight Vehicle Structures 3 Edition, 2019

Ailerons are the primary flight control surfaces that move the aircraft about the longitudinal axis. In other words, movement of the ailerons in flight causes the aircraft to roll. Ailerons are usually located on the outboard trailing edge of each of the wings. They are built into the wing and are calculated as part of the wing’s surface area. Figure 1-53 shows aileron locations on various wing tip designs.

Figure 22.16.7‑1: Different Aileron Layouts  (FAA-H-8083-31, 2012)

Ailerons are controlled by a side-to-side motion of the control stick in the cockpit or a rotation of the control yoke. When the aileron on one wing deflects down, the aileron on the opposite wing deflects upward. This amplifies the movement of the aircraft around the longitudinal axis. On the wing on which the aileron trailing edge moves downward, camber is increased, and lift is increased. Conversely, on the other wing, the raised aileron decreases lift. [Figure 1-54] The result is a sensitive response to the control input to roll the aircraft

Figure 22.16.7‑2: Yoke and Relative Aileron Movements  (FAA-H-8083-31, 2012)

The pilot’s request for aileron movement and roll are transmitted from the cockpit to the actual control surface in a variety of ways depending on the aircraft. A system of control cables and pulleys, push-pull tubes, hydraulics, electric, or a combination of these can be employed.

Figure 22.16.7‑3: Typical Joystick Aircraft Control System  (FAA-H-8083-31, 2012)

Simple, light aircraft usually do not have hydraulic or electric fly-by-wire aileron control. These are found on heavy and high-performance aircraft. Large aircraft and some high-performance aircraft may also have a second set of ailerons located inboard on the trailing edge of the wings. These are part of a complex system of primary and secondary control surfaces used to provide lateral control and stability in flight. At low speeds, the ailerons may be augmented using flaps and spoilers. At high speeds, only inboard aileron deflection is required to roll the aircraft while the other control surfaces are locked out or remain stationary. Figure 1-56 illustrates the location of the typical flight control surfaces found on a transport category aircraft.

Figure 22.16.7‑4: Typical Transport Category Aileron and Spoiler Layout  (FAA-H-8083-31, 2012)

Figure 1-52 illustrates several aileron configurations with their hinge points well aft of the leading edge. This is a common design feature used to prevent flutter.

Figure 22.16.7‑5: Different Aileron Hinge line Configurations  (FAA-H-8083-31, 2012)

22.16.7. Ailerons & Elevons

Reference:  Abbott, Richard. Analysis and Design of Composite and Metallic Flight Vehicle Structures 3 Edition, 2019

Ailerons are the primary flight control surfaces that move the aircraft about the longitudinal axis. In other words, movement of the ailerons in flight causes the aircraft to roll. Ailerons are usually located on the outboard trailing edge of each of the wings. They are built into the wing and are calculated as part of the wing’s surface area. Figure 1-53 shows aileron locations on various wing tip designs.

Figure 22.16.7‑1: Different Aileron Layouts  (FAA-H-8083-31, 2012)

Ailerons are controlled by a side-to-side motion of the control stick in the cockpit or a rotation of the control yoke. When the aileron on one wing deflects down, the aileron on the opposite wing deflects upward. This amplifies the movement of the aircraft around the longitudinal axis. On the wing on which the aileron trailing edge moves downward, camber is increased, and lift is increased. Conversely, on the other wing, the raised aileron decreases lift. [Figure 1-54] The result is a sensitive response to the control input to roll the aircraft

Figure 22.16.7‑2: Yoke and Relative Aileron Movements  (FAA-H-8083-31, 2012)

The pilot’s request for aileron movement and roll are transmitted from the cockpit to the actual control surface in a variety of ways depending on the aircraft. A system of control cables and pulleys, push-pull tubes, hydraulics, electric, or a combination of these can be employed.

Figure 22.16.7‑3: Typical Joystick Aircraft Control System  (FAA-H-8083-31, 2012)

Simple, light aircraft usually do not have hydraulic or electric fly-by-wire aileron control. These are found on heavy and high-performance aircraft. Large aircraft and some high-performance aircraft may also have a second set of ailerons located inboard on the trailing edge of the wings. These are part of a complex system of primary and secondary control surfaces used to provide lateral control and stability in flight. At low speeds, the ailerons may be augmented using flaps and spoilers. At high speeds, only inboard aileron deflection is required to roll the aircraft while the other control surfaces are locked out or remain stationary. Figure 1-56 illustrates the location of the typical flight control surfaces found on a transport category aircraft.

Figure 22.16.7‑4: Typical Transport Category Aileron and Spoiler Layout  (FAA-H-8083-31, 2012)

Figure 1-52 illustrates several aileron configurations with their hinge points well aft of the leading edge. This is a common design feature used to prevent flutter.

Figure 22.16.7‑5: Different Aileron Hinge line Configurations  (FAA-H-8083-31, 2012)