The bore of the engine is the diameter of the cylinders, and the stroke is the distance the piston moves from the top of its travel to the bottom.
square mil. A unit of area possessed by a square having sides of one mil, or one thousandth of an inch
(0.001 inch).
square of a number (mathematics). The product of a number multiplied by itself.
square root (mathematics). A number which, when multiplied by itself, will give a particular number.
square wave (electrical waveform). The waveform produced by pulsating direct current in which the voltage alternates between zero and its maximum value. It changes almost instantaneously from zero to its maximum value, remains at this value for a given period of time, and then returns instantly to zero. The length of time the voltage remains at maximum is the same as the time it remains at zero.
Alternating current can also have a square wave if the voltage changes almost instantaneously from its maximum positive value to its maximum negative value. The voltage at both the maximum positive and the maximum negative values remains constant until it shifts to the opposite value. The voltage remains positive for the same length of time it remains negative.
square-wave generator (electronic device). An electronic device that produces alternating current with a square waveform. The frequency and the amplitude of the square-wave AC can be changed to any value desired.
squaring shear (sheet metal shop tool). A large shear used to make straight cuts across a sheet of metal. Squaring shears used for light-gage steel and thin aluminum alloy sheets are operated by a foot pedal, and shears used to cut heavy plate steel are operated by energy stored in a large flywheel by a small electric motor.
squat switch (aircraft safety switch). A switch mounted on the shock strut of an aircraft landing gear. The squat switch is in a circuit whose actuation depends upon the configuration of the landing gear. For example, the squat switch prevents the landing gear retraction handle being moved any time weight is on the landing gear. A squat switch can also be installed in the cabin pressurization system to prevent the cabin being pressurized if the airplane is on the ground and weight is on the landing gear.
“Squawk” (air traffic control). A term used by ATC to request a pilot to activate specific modes, codes, or functions on the aircraft transponder. For example, “squawk three/alpha, two one zero five, low.”
“Squawk ident” (air traffic control). A phrase used by ATC to request a pilot to activate the ident feature on the aircraft transponder. Activation of the ident feature allows the ground controller to immediately identify the aircraft that is squawking.
squealer tip (compressor blade tip). See profile tip.
squeegee. A rubber scraper blade mounted on a handle in such a way that the blade forms a T with the handle. Squeegees are used to move a liquid over a surface. Some of the common uses for squeegees are removing water from a window after the window has been washed, spreading paint through the open fibers in a silk screen, and removing water from a photographic print after it has been washed.
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