时间：2011-03-11 23:18来源：蓝天飞行翻译 作者：航空 点击：次
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vibrator (electrical component). An electromagnetic relay used to change steady direct current into pulsating DC. Current flowing through a relay coil produces an electromagnetic pull that opens a set of contacts that are normally held closed by a spring. The coil and contacts are connected in series so the current flowing in the coil stops as soon as the contacts open. When the contacts open, the coil loses its electromagnetic pull, and the spring closes the contacts, restoring the current to the coil. The frequency of the pulsating DC is determined by the magnetic characteristics of the relay. vibrator-type voltage regulator (DC generator control). A voltage control used with some of the simpler direct current generators. The voltage sensor is an electromagnetic relay whose coil is connected across the generator output. The relay contacts are in the generator field circuit. As soon as the generator output voltage reaches the value for which the voltage regulator is set, the electromagnetic field in the relay pulls the contacts open. Field current is reduced and the generator output voltage drops. As soon as the voltage is low enough, the relay contacts close and field current again flows. The contacts vibrate open and closed several hundred times a minute to hold the generator voltage within the desired range. vibratory torque control (reciprocating engine component). A patented coupling between the propeller shaft and the crankshaft of the Continental Tiara series aircraft engines. A short quill shaft absorbs torsional vibrations under certain operating conditions, and a centrifugal lock bypasses the quill shaft under conditions in which a solid shaft will produce less vibration. See quill shaft. video amplifier (electronic component). An electronic amplifier capable of amplifying alternating current over a wide band of frequencies. Video amplifiers normally amplify AC over a frequency band of from about 15 hertz to five megahertz (5,000,000 hertz). video map. An electronically displayed map on the radar display that may depict data such as airports, heliports, runway center line extensions, hospital emergency landing areas, navaids and fixes, reporting points, airway/route center lines, boundaries, hand-off points, special use tracks, obstructions, prominent geographical features, map alignment indicators, range accuracy marks, and minimum vectoring altitudes. VIFF (vectoring in forward flight). The ability of the pilot of an aircraft equipped with a vectored-thrust engine to change the direction of the exhaust gas flow while the aircraft is in forward flight. VIFF allows the pilot to accomplish flight maneuvers that are impossible with a conventional engine installation. VI (viscosity index) improver. An additive used to produce a multiviscosity lubricating oil. The polymer additive expands as temperature increases and contracts as the temperature decreases. VI improvers cause the viscosity to increase as the oil becomes hot and decrease when it becomes cold. |
