Auxiliary Lift Devices

Lift, a mechanical aerodynamic force produced by the motion of an aircraft moving through the air, is the force that directly opposes the weight of an aircraft and holds the aircraft in the air. Lift is generated by all parts of the aircraft, but the majority of lift is generated by the wings. Despite this, there are additional components, known as auxiliary lift devices, that create additional lift. The most common auxiliary lift devices are the wing flaps, spoilers/speed brakes, slats/leading edge flaps, and slots.

Each lift device is divided into one of two groups: devices that augment (increase) lift, and devices that decrease lift. Let’s take a look at both groups. In the lift augmenting group are flaps, slats, and slots. Flaps are located on the trailing edge of the wing and are moveable to increase the wing area. This increases lift during takeoff and decreases speed upon landing. Most flaps are retractable and fair into the wing contour, while others are simply a portion of the lower skin which extends into the airstream, thereby slowing the aircraft.

Slats, also known as leading edge flaps, are airfoils that extend from and retract into the wing’s leading edge. Some installations create a slot, or an opening between the extended airfoil and leading edge. At low speed, the slot increases lift and improves handling characteristics, allowing the aircraft to be controlled at airspeeds under the typical landing speed. In other installations, there are permanent slots built into the leading edge of the wing. At cruising speeds, the trailing and leading edge slats are retracted into the wing.

The lift decreasing devices are the spoilers or speed brakes. In some aircraft, there are two types of spoilers. The ground spoiler is used only once the aircraft is on ground to assist in the braking action. The flight spoiler helps provide lateral control by extending when the aileron on the wing is rotated up. When used as speed brakes, the spoiler panels on both wings raise up. Flight spoilers can be located along the sides of the aircraft, under the fuselage, or at the tail. In many aircraft designs, the wing panel on the upper aileron side rises more than that of the down aileron side. This provides both lateral control and speed brake operation at the same time.

Three other types of auxiliary lift devices are winglets, canard wings, and wing fences. Winglets are near-vertical extensions of the wingtip that help minimize aerodynamic drag from vortices that develop at the wingtips during flight. By reducing drag at the wingtips, winglets also lower fuel consumption and increase range. A canard wing is a type of aircraft with an aircraft configuration in which a small wing or horizontal airflow is ahead of the main lifting surfaces, rather than behind them. These can be fixed, movable, or designed with elevators. Finally, wing fences are flat, metal vertical plates affixed to the upper surface of a wing. They are designed to obstruct airflow along the span of the wing and prevent the entire wing from stalling at once.

For auxiliary lift devices of all types and more, look no further than ASAP Components. 

• tony adams
• Posted on April 22, 2021
aviation

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