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wingA broad feature occurring on one side of the position of a spectral line or band. The matter producing this feature is traveling at much greater speeds than that producing the main peak and thus has a greater Doppler shift. A redshifted wing (i.e. shifted to longer wavelengths) is produced by gas receding from us, a blueshifted (shorter-wavelength) wing by gas moving toward us.
the part of an aircraft (airplane, glider, or winged missile) whose primary function is to produce lift during flight in the atmosphere. Wings are classified in three projections (views): top (parallel, delta, or tapered), side (according to the type of section; see Figure 1), and front (dihedral, inverted-gull, or gull wings; wings with recurved ends; and curvilinear wings).
The structural basis of the two symmetrically positioned parts of a wing are longitudinal and transverse sets of elements (spars, stringers, and ribs) to which the wing root fittings and skin are attached (Figure 2). If necessary, slats and leading-edge flaps are installed in the leading edge, and ailerons, flaps, and trim tabs are installed in the trailing edge. Fuel tanks, landing gear, contorl
cables for the movable aerodynamic surfaces, heating and cooling apparatus, and various equipment, as well as engines and armament, are usually placed inside the wing. In flight and during landing, a wing operates like a hollow beam, which is able to absorb air and inertial loads in any direction.
The wings of subsonic aircraft are made of Duralumin, high-tensile steel, composition materials, reinforced plastics, and alloys of titanium, magnesium, and beryllium. Wood, plywood, and cloth are used primarily for light airplanes and gliders. Heat-resistant alloys of vanadium, tantalum, tungsten, and other refractory metals, as well as heat-shielding coatings and heat-insulating materials, are used for the wings of supersonic and hypersonic aircraft and spacecraft, which undergo intense heating during flight in the atmosphere. The efficiency of a wing is rated according to many parameters, the most important of which are the aerodynamic properties, the mass ratio, the torsional and flexural stiffness, the technological and service qualities, and the production cost.
S. IA. MAKAROV
(1) A term designating the right or left part of the disposition, combat formation, or operational concentration of troops, for instance, the right or left wing of an army or a front.
(2) In the US Air Force a wing is the basic organizational and tactical military unit. Depending on the mission and the armament, wings are divided into heavy-bomber, medium-bomber, aerospace (rocket), reconnaissance, and service wings. A wing has a staff, from two to five squadrons, airfield-service groups, and subunits of matériel support. Two or three wings make up an air division.
A lifting surface of a heavier-than-air object, either bird or airplane. Lift is created by a pressure difference between the upper and lower surfaces of the wing, the average pressure on the upper surface being lower. The average velocity on the upper surface is larger than on the lower surface, resulting in the lifting pressure difference in accordance with Bernoulli's theorem. The velocity difference is caused by having a greater curvature on the wing upper surface, or a positive wing angle of attack (that is, leading edge up), or both. The amount of lift is proportional to the angle of attack, the wing area, the air density, and the square of the velocity. See Aerodynamic force, Subsonic flight
The important physical characteristics of a wing are wing area, measured in the plan or top view, the span or distance from the left wing tip to the right wing tip, the aspect ratio, the taper ratio, and the thickness ratios of the airfoils. The aspect ratio is the ratio of the span to the average chord. The chord of a wing is the distance from the leading edge to the trailing edge. In all but the simplest airplanes, the chord varies along the span, being largest at the root. The taper ratio is the ratio of the tip chord to the root chord. Airfoils are the cross-sectional shapes of wings as defined by the intersections with planes parallel to the oncoming airstream and perpendicular to the plane of the wing surface. The thickness ratio is the ratio of the maximum thickness of an airfoil to the chord and often varies between the root and tip. If an airfoil has greater curvature on the upper surface than on the lower surface, the mean line midway between the upper and lower surfaces is curved. The amount of this curvature is called camber. All of these wing characteristics affect flight efficiency and must be carefully chosen. See Aircraft design
There is a particular angle of attack of a wing that provides the necessary lift with the least drag. Wing area selection attempts to have the airplane fly at this angle of attack at the desired speed and within the range of desirable altitudes. Of course, takeoff and landing fields are important in area selection. A larger wing area permits slower flight, which is associated with shorter takeoff acceleration distances and shorter stopping distances after landing.
Wings must be designed to stall safely. Above the maximum angle of attack at which the flow will remain smoothly attached to the wing surface, there is a sharp loss of lift and a large increase in drag. This is known as the stall, a condition that is normally avoided. Wings are designed to stall near the root first so that the tendency to roll sharply is minimized and the ailerons on the outer wing remain effective. This is done by varying the airfoil sections and thickness ratios across the span in a careful manner.
The flight of airplanes is controlled primarily by varying the magnitude and direction of the wing lift and by varying the thrust or power contributed by the engines. An important aspect of flight is the speed, which is controlled by adjusting the wing angle of attack with respect to the oncoming airstream. The angle of attack is adjusted by varying the angle of the elevator, a control surface usually located on the horizontal tail. After adjusting the flight speed by using the elevators, the angle of the flight path, zero for level flight, is controlled by setting the engine thrust.
The direction of flight is basically controlled by the angle of bank of the wing. When the wing is level and the resultant force, or lift, is vertical, the airplane flies in a straight line. Ailerons are trailing-edge flaps on the outer part of the wing that deflect in opposite directions on the left and right sides of the airplane. When the airplane banks or rolls because of the deflection of ailerons, the lift force is tilted toward the side since it remains perpendicular to the banked wing. This provides a sidewise force which accelerates the airplane in a direction perpendicular to the flight path and thereby curves the flight path. Application of the rudder keeps the airplane pointed into the wind during the turn, although the vertical tail will do much of that job even without rudder deflection
High-speed aircraft also use spoilers, essentially plates ahead of the flaps, to lose lift on only one side to roll the airplane. These spoilers are also used symmetrically to slow down an airplane and increase the rate of descent. Spoilers are also used after touchdown to quickly reduce lift and dump the weight on the braked wheels, thereby greatly improving the stopping effectiveness.
Wings also carry moving elements that serve lift-increase functions. Trailing-edge flaps (see illustration) inboard of the ailerons increase the lift that can be carried before the stall. Thus the minimum flight speed can be decreased. Leading-edge flaps and slats (see illustration) are used to increase the angle of attack for stall and further reduce the minimum flight speed. The primary purpose of increasing the lift capability and obtaining the lowest flight speed is to reduce the required field lengths for takeoff and landing or to reduce the necessary wing area. See Flight controls
Wings also serve as fuel tanks, a function that sometimes sets the minimum wing area—especially on small aircraft such as executive jets. Wing thickness ratio is important in determining the volume available for fuel within the wing. Wings often house all or part of the landing gear. Engines are mounted on the wing of many aircraft. See Aircraft engine, Airplane, Landing gear