Spoilers and Ailerons

Spoilers on top of a wing serve the opposite purpose from flaps and slats. When a spoiler is raised, it spoils the wing’s aerodynamic shape, increases drag, and cuts the amount of lift. Spoilers are used to cut lift after an airplane has landed. They may be used to help a big, heavy plane turn. The spoilers on one wing are raised to help the ailerons.

Ailerons are panels in the trailing edge of an airplane’s wings that are used for turning the plane. One aileron tilts up, and the other tilts down. One wing produces more lift than the other and rises. The wing that produces less lift falls, and the plane rolls into a turn. Big airliners often have two sets of ailerons. The ailerons closest to the wingtips have more leverage for rolling the plane at low speeds. At high speed, the ailerons closest to the fuselage have enough leverage to turn the plane.

Supercritical Wings

As a normal wing nears the speed of sound, a high-pressure shock wave forms on top of it. This causes drag, which makes it difficult for an aircraft to go faster without using a lot more engine power. It also makes an aircraft harder to control.

Simply by changing the shape of the airfoil, the shock waves can be made smaller. Airfoils changed in this way are called supercritical wings. In a supercritical wing, the upper surface is flattened and the curve at the trailing edge is increased. Planes with supercritical wings can go faster with less engine power. Although supercritical wings were developed for supersonic aircraft, they also can produce a lot of lift at low speeds, so they are used by cargo aircraft. The extra lift is good for getting heavy loads off the ground at low speeds.

Other Kinds of Wings

Fixed-wing airplanes are not the only aircraft that use wings. A helicopter’s rotor blades are actually long, thin wings. High-performance parachutes called parafoils are really inflatable wings. The parachute is made of two layers of fabric with dividers between them, forming a line of pockets, or cells. As the parachute moves along, air fills the cells and forms a wing shape.

The parachutist controls and steers the parafoil by pulling control lines that change the wing’s shape.

A flexible fabric hang glider is yet another type of wing. Called a Rogallo wing, this early hang glider was developed in the 1940s by husband and wife, Francis and Gertrude Rogallo. When space exploration began, NASA investigated the Rogallo wing as a way of landing the Gemini manned spacecraft. Round parachutes eventually were used instead, but the Rogallo wing was used by other designers, who developed it into the modern hang glider. Racecars also use wings. However, racecar wings do the opposite job of aircraft wings. They produce a downward force, called downforce, when they cut through air. This pushes the car down harder against the ground, giving its tires better grip, and enabling it to take corners faster without loss of traction.

The anatomy of an airplane wing

The front edge of a wing also is called its leading edge, and the back edge is the trailing edge. The measurement from the leading edge straight back to the trailing edge is the wing’s chord. The length from one wingtip to the other is the wingspan. The curvature of the top and bottom of a wing is called its camber. The part of a wing where it joins a plane’s fuselage is the wing root. A wing’s aspect ratio is a measure of how long and slender it is. A wing that has a high aspect ratio (long and slender) causes less drag, so it is good for gliding. Wings usually tilt up from an airplane’s body toward the wingtips, forming a shallow V shape. The angle of this tilt is called the dihedral, and the wing’s dihedral makes an airplane more stable.