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superheat-The amount by which the temperature of
the gas in the envelope or gas cells of an aerostat
exceeds the temperature of the surrounding air. If
the gas has a lower temperature, the superheat is said
to be negative.
superpressure-The excess of pressure at the bottom 
of an airship gas cell or envelope over the outside
atmospheric pressure.
suspension band-See BAND, SUSPENSION.
suspension bar (or ring)-A bar to which the suspension ropes of the balloon basket are secured. It is 
also fitted with ropes and toggles for attachment 
to the basket suspensions from the envelope or net;
also called "trapeze bar."
suspension, basket-The suspension by means of which
the basket of a kite balloon is supported beneath the
balloon body proper. It is independent of the winch
suspension, winch-The rigging by means of which the lift and drag of a kite balloon are transmitted from the envelope to the towing or traction cable.
sweepback-The acute angle between a line perpendicular to the plane of symmetry and the plan projection of a reference line in the wing. (See fig. 5.)
tab-An auxiliary airfoil attached to a control surface for the purpose of reducing the control force or trimming the aircraft.
tachometer-An instrument that measures in revolutions per minute the rate at which the crankshaft of an engine turns.
tail, airplane-The rear part of an airplane, usually consisting of a group of stabilizing planes, or fins, to which are attached certain controlling surfaces such as elevators and rudders; also called "empennage."
tail boom-A spar or outrigger connecting the tail surfaces and the main supporting surfaces.
tail drag-A movable or variable weight suspended from the after part of an airship moored to a mast, to aid in restraining the vertical and lateral motions of the stern of the airship.
tailheavy-The condition of an airplane in which the tail tends to sink when the longitudinal control is released in any given attitude of normal flight (cf. noseheavy).
tail skid-A skid for supporting the tail of an airplane on the ground. (See fig. 5.)
tailless airplane-See AIRPLANE, TAILLESS.
tail slide-Rearward motion, relative to the air of an aircraft in flight.
tail surface-A stabilizing or control surface in the tail of an aircraft.
tail wheel-See WHEEL, TAIL.
take-off-The act of beginning flight in which an airplane is accelerated from a state of rest to that of normal flight. In a more restricted sense, the final breaking of contact with the land or water.
take-off distance-The distance in which an airplane will finally break contact with the land or water, starting from zero speed. Take-off distance is considered in a calm or at a specified wind velocity.
tank, seaplane-An elongated tank filled with water through which models of seaplane floats, boat hulls, hydrovanes, etc., are towed, and the forces and moments on the model are measured.
tank, service-A fixed fuel tank near each power unit, into which fuel from other tanks is pumped and from which the fuel supplying the engine is drawn. 
taper in plan only-A gradual change (usually a decrease) in the chord length along the wing span from the root to the tip, with the wing sections remaining geometrically similar.
taper in thickness ratio only-A gradual change in the thickness ratio along with the wing span with the chord remaining constant. 
taxi-To operate an airplane under its own power, either on land or on water, except as necessarily involved in take-off or landing.
taxiway-A specially prepared area over which airplanes may taxi to and from the landing area of a landing field. 
tee, wind-See WIND TEE.
terminal velocity-See VELOCITY, TERMINAL.
test chamber-See EXPERIMENT CHAMBER.
thickness ratio-The ratio of the maximum thickness of an airfoil section to its chord.
three-point landing-See LANDING, THREE-POINT.
thrust, effective propeller-See PROPELLER THRUST EFFECTIVE.
thrust, propeller-See PROPELLER THRUST.
thrust, static propeller-See PROPELLER THRUST, STATIC.
tip radius (or propeller radius)-The distance of the outermost point of a propeller blade from the axis of rotation.
torque stand-A test stand on which the engine torque is measured.
towing sleeve-See SLEEVE, TOWING.
tractor airplane-See AIRPLANE, TRACTOR.
traffic-control projector- A projector designed to give light signals to an aircraft pilot.
trailing edge-The rearmost edge of an airfoil or of a propeller blade.
trail rope-See DRAG ROPE.
trajectory band-See BAND, TRAJECTORY.
transition strip-A section of the landing area adjacent to a runway or other hard-surfaced area, constructed of crushed stone, or other suitable material, properly bound, to insure the safe landing and taxying of airplanes across such a runway or area in any direction.
    intermediate transverse-An open unbraced transverse 
    frame of a rigid airship between two main or braced
    transverse frames.