center’s area (air traffic control). Specified airspace within which an air traffic control center (ARTCC) provides air traffic control and advisory service.
center-tapped winding (electrical transformer winding). A winding on an electrical transformer that has a tap, or connection, located in its electrical center. A center tap is used to divide the winding into two halves which have opposite polarities. A center-tapped secondary winding of a power transformer is needed for a two-diode, full-wave rectifier.
center weather advisory (meteorology). An unscheduled weather advisory issued by center weather service unit meteorologists for ATC use to alert pilots of existing or anticipated adverse weather conditions within the next two hours.
centigrade temperature. The name formerly used for Celsius temperature. The name centigrade means 100 graduations. See Celsius temperature.
centimeter-gram-second system. The system of metric measurement in which the centimeter is the basic unit of linear measurement, the gram is the basic unit of mass, and the second is the basic unit of time. This is known as the cgs system.
central processing unit (digital computer). See CPU.
central refueling system (aircraft fuel system). A type of fuel system used in large aircraft that allows all the fuel tanks to be fueled from a single point, usually under the wing.
A central refueling system is also called a single-point fueling system, or a pressure fueling system.
centrifugal brake. A friction brake used on a hoist drum. A centrifugal brake automatically applies friction to stop the hoist if the drum ever turns at a speed faster than is allowed.
centrifugal clutch. A form of friction clutch that engages when the drive wheel reaches a certain speed. The clutch is engaged by centrifugal force acting on a flyweight mechanism.
centrifugal compressor (gas turbine engine component). A compressor in a gas turbine engine that uses a scroll-type impeller.
Air is taken into the center, or eye, of the impeller and slung outward by centrifugal force into the diffuser where its velocity is decreased and its pressure increased.
Centrifugal compressors were used on the first gas turbine aircraft engines, and are used on some modern engines as a high-pressure stage that receives its input air from a low-pressure axial-flow stage.
centrifugal filter. A filter that separates contaminants from a fluid by centrifugal action. The contaminants are thrown by rotary motion into traps that hold them until they can be removed.
centrifugal force. A force that acts outwardly on any body moving in a curved path. Centrifugal force tries to move a body away from the center of its rotation, and this force is opposed by centripetal force.
centrifugal moment. A force which tries to cause rotation. A centrifugal moment is the product of the amount of centrifugal force acting on an object, multiplied by the distance between the object and the center of its rotation.
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