A wing tip is a point on an aircraft wing that is most distant from the main fuselage. They may house special markings or equipment such as lights or landing gear. Wing tips have an important impact on an aircraft’s aerodynamic properties and are often optimized to reduce drag. This reduction in drag can translate into lower fuel consumption; many airlines have retrofitted older planes with wing tip devices as a result.
Wing tips have been a fixture of fixed-wing aircraft since the days of the Wright brothers. Any aircraft with a wing has at least two wing tips located at the most distant points from the fuselage. Their shape, size, and function varies greatly; in some aircraft, wing tips simply mark the end of a wing, while others use them as a mounting point for lights, landing gear, fuel tanks, or other equipment.
Special attention is paid to wing tips because of their impact on an airplane’s aerodynamics. Most people are aware that a plane’s wings generate lift, but fewer know that a wing can also create drag as a byproduct of that lift. As the relatively low-pressure air above the wing meets the higher-pressure air beneath the wing, swirling masses of turbulent air known as vortices are formed. The end result is a force called induced drag that acts against the airplane’s forward movement. The vortices around a wing tip are the most extreme; therefore aircraft designers often focus on these areas when trying to reduce drag.
Changing the shape and size of the wing tips is one way to cut down on the amount of induced drag an aircraft’s wings create. In World War II, several Allied fighter planes had elliptical wings that were rounded off at both ends, thus reducing drag and giving the fighters slight speed boosts. While these types of wings worked well, they proved difficult to manufacture, and more modern aircraft usually feature other types of enhancements. Some large airliners feature raked wing tips with a different angle than the rest of the wing, while other aircraft have wing tip devices, which are structures attached to the wings.
As steeper oil prices began to cut into profitability, the commercial aviation industry became increasingly interested in wing tip devices beginning in the first few years of the 21st Century. These devices reduce drag, provide a small but meaningful reduction in fuel consumption, and can also minimize noise levels during takeoff and landing. Some of the most popular wing tip devices include winglets, i.e., nearly vertical fins that rise above the end of each wing, blended winglets, which are similar to winglets but are affixed with a gentle curve instead of a sharp angle, and fenced wing tips, which have a fin-like structure that protrudes both above and below the wing. Many older aircraft have been retrofitted with these devices, and aircraft manufacturers now routinely offer them as options on new planes.