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swaged (hammered into) the cable with special swaging dies.
The swaging dies compress the cylinder, and as the inside of the hole becomes smaller than the
outside of the cable, the metal of the terminal is pressed around the wires of the cable. A properly swaged
terminal develops the full strength of the steel cable.
SWAP (severe weather avoidance plan) (air traffic control). An approved plan to minimize the effect of
severe weather on traffic flows in impacted terminal and/or ARTCC areas. SWAP is normally implemented
to provide the least disruption to the air traffic control system when flight through portions of airspace is
difficult or impossible due to severe weather.
swash plate. The component in a helicopter control system that consists basically of two bearing races with
ball bearings between them. The lower, or nonrotating, race is tilted by the cyclic control, and the upper, or
rotating, race has arms which connect to the control horns on the rotor blades.
Movement of the cyclic pitch control is transmitted to the rotating blades through the swash plate.
Movement of the collective pitch control raises or lowers the entire swash plate assembly to change the
pitch of all of the blades at the same time.
sweat soldering. A method of soldering two pieces of sheet metal together. Both surfaces that form the
seam are tinned (covered with a thin coating of solder), and the joint is assembled. The entire assembly is
put into an oven and heated enough to melt the solder in the joint and produce a tight, uniform seal.
sweptback wing (airplane wing). An airplane wing in which the leading edge angles backward from the
fuselage. The leading edge of the wing at the tip is farther back than the leading edge at the root.
swinging choke (electrical component). A special type of iron-core inductor used in a filter circuit for an
electrical power supply. A swinging choke is built in such a way that its effective inductive reactance varies
with the amount of current flowing through its winding.
switch (electrical circuit component). A component used to open or close an electrical circuit or to select
paths through the circuit.
switching diode (electronic component). A type of semiconductor diode whose resistance varies with the
voltage across it. A switching diode acts as an open switch when the voltage across it is low, but when the
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
Page 566
voltage rises to a certain value, its resistance decreases, and the diode conducts, acting as a closed switch.
symmetrical airfoil. An airfoil that has the same shape on both sides of its center line. A symmetrical
airfoil has a very small change in the location of its center of pressure as its angle of attack changes. For
this reason, symmetrical airfoils are often used for helicopter rotors.
symmetry check (rigging check). A dimensional check of an airframe to determine that the wings and tail
are symmetrical about the longitudinal axis.
synchro (remote indicating device). A device used to transmit indications of angular movement or
position from one location to another. See Autosyn system.
synchronous motor (electric motor). An alternating current motor similar to an induction motor, except
the rotor is either a permanent magnet or an electromagnet excited by an external source of direct current.
The rotor of a synchronous motor turns at a speed directly related to the frequency of the alternating current
used to excite its stator.
synchronous speed (induction motor). The speed of an induction motor at which the rotor follows the
rotating field in the stator. The synchronous speed, in revolutions per minute, is found by dividing the
frequency of the AC, in hertz, by the number of poles in the stator. Then multiplying this answer by 120. A
four-pole induction motor, operating on 60-hertz AC, has a synchronous speed of 1,800 RPM.
synchrophasing (propeller operation). A method of synchronizing the propellers of a multiengine aircraft.
The engines all turn at the same RPM, and the propellers rotate in such a way that a master blade on each
propeller keeps the same relative position in its rotation as the master blade on each of the other propellers.
synchroscope (aircraft instrument). A powerplant instrument used on multiengine aircraft to detect and
display the difference in rotational speed of the various engines. One popular type of synchroscope has a
small propeller on the face of the instrument. The propeller rotates at a speed and in a direction determined
by the difference in RPM of the master engine and the other engine. When the propeller on the instrument
face is not rotating, the two engines are turning at exactly the same speed.
synchro system (remote indicating system). A type of remote indicating system that uses synchro motors
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航空术语词典Dictionary of Aeronautical Terms 下(79)
