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29 
NOMENCLATURE FOR AERONAUTICS

weight-continued.
fixed weight (airship)-The weight of the machinery and all equipment and parts that are fixed in position and nonconsumable. Liquids in the cooling systems of the engines are included.
fixed power plant weight for a given airplane weight-The weight of the power plant and its accessories, exclusive of fuel and oil and their tanks.
gross weight (airplane)-The total weight of an airplane when fully loaded. (cf. load, full.)
net weight (stress analysis)- The gross weight, less some specific partial weight. Very often the partial weight is the dead weight of the wings, but it may be the useful load. The partial weight in question should always be clearly indicated by the context.
wheel control-See CONTROL COLUMN.
wheel, tail-A wheel used to support the tail of an airplane when on the ground. It may be steerable or nonsteerable, fied or swiveling.
winch suspension-See SUSPENSION, WINCH.
wind cone-See CONE, WIND.
wind indicator-A device that indicates the direction and velocity of the surface wind.
wind, relative-The velocity of the air with reference to a body in it. It is usually determined from measurements made at such a distance from the body that the disturbing effect of the body upon the air is negligible.
window, inspection-A small transparent window fitted in the envelope of a balloon or airship, or in the wing or fuselage of an airplane, to allow inspection of the interior. (See figs. 3 and 5)
wind tee-A large T-shaped weather vane located on a landing field or on the top of an adjacent structure to indicate the direction of the wind. It may have the form of an airplane and may be illuminated for night landings. Also called "landing tee."
wind tunnel-An apparatus producing an artificial wind or air stream, in which objects are placed for investigating the air flow about them and the aerodynamic forces exerted on them (fig. 7).
wing-A general term applied to the airfoil, or one of the airfoils designed to develop a major part of the lift of a heavier-than-air craft.
equivalent wing (stress analysis)-A wing of the same span as the actual wing, but with the chord at each section reduced in proportion to the ratio of the average beam load at that section to the average beam load at the section taken as the standard.
wing area-See AREA, MEASUREMENT OF.
wing axis-See AXIS, WING.
wingheavy, right or left-The condition of an airplane whose right or left wing tends to sing when the lateral control is released in any given attitude of normal flight.
wing loading-See LOADING, WING.
wing-over-A maneuver in which the airplane is put into a climbing turn until nearly stalled, at which point the nose is allowed to fall while continuing the turn, then returned to normal flight from the ensuing dive or glide in a direction approximately 180 degrees from that at the start of the evolution (fig. 8).
wing profile-The outline of a wing section.
wing rib-A chord-wise member of the wing structure of an airplane, used to give the wing section its form and to transmit the load from the fabric to the spars.
compression wing rib-A heavy rib designed to perform the function of an ordinary wing rib and also to act as a strut opposing the pull of the wires in the internal drag truss.
former (or false) wing rib-An incomplete rib, frequently consisting only of a strip of a strip of wood extending from the leading edge to the front spar, which is used to assist in maintaining the form of the wing where the curvature of the airfoil section is sharpest. (See fig. 5.)
wing section-A cross section of a wing parallel to the plane of symmetry or to a specified reference plane.
wing section, aerodynamic center of-See AERODYNAMIC CENTER.
wing skid-A skid placed near the wing tip to protect the wing from contact with the ground.
wing spar-A principal span-wise member of the wing structure of an airplane. (See fig. 5.)
wing tip-The outer end of an airplane wing.
wing-tip flare-See FLARE, WING-TIP.
wing-tip rake-A term referring to the shape of the tip of the wing when the tip edge is sensibly straight in plan but is not parallel to the plane of symmetry. The amount of rake is measured by the acute angle between the straight portion of the wing tip and the plane of symmetry. The rake is positive when the trailing edge is longer than the leading edge.
wire (airplane):
antidrag wire-A wire intended primarily to resist the forces acting forward in the chord direction. It is generally enclosed in the wing. (See fig. 5.)
drag wire-A wire intended primarily to resist the forces acting backward in the chord direction. It is generally enclosed in the wing. (See fig. 5.)
landing wire-A wire or cable which braces the wing against the forces opposite to the normal direction of the lift. (See fig. 5.)
lift wire-A wire or cable which braces the wings against the lift force; sometimes called "flying wire." (See fig. 5.)
stagger wire-A wire connecting the upper and lower wings of an airplane and lying in a plane substantially parallel to the plane of symmetry; also called "incidence wire." (See fig. 5.)