時間：2011-03-11 23:11來源：藍(lán)天飛行翻譯 作者：admin 點(diǎn)擊：次
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beryllium bronze. An alloy of copper combined with about three percent beryllium. Beryllium bronze is used for making springs, bellows, and diaphragms for pressure-measuring instruments. best angle-of-climb airspeed (VX). The airspeed at which an aircraft will gain the greatest amount of altitude in a given distance. best-economy mixture (reciprocating engine fuel-air mixture ratio). The fuel-air mixture ratio used in a reciprocating engine that gives the aircraft its greatest range of flight. The best-economy fuel-air mixture ratio, which is in the range of 0.055 to 0.065 (18:1 to 15:1 air-fuel ratio). This mixture ratio does not provide any additional fuel for cooling, so it can be used only when the engine is operating with reduced power. best-power mixture (reciprocating engine fuel-air mixture ratio). The fuel-air mixture ratio used in a reciprocating engine that allows the engine to develop its greatest amount of power. The best-power fuel-air mixture ratio, which is in the range of 0.074 to 0.087 (13.5:1 to 11.5:1 air-fuel ratio), is richer than the ratio used for the best economy. The additional fuel in this mixture is used to remove some of the heat from the cylinders when the engine is producing its best power. best rate-of-climb airspeed (VY). The airspeed at which an aircraft will gain the greatest amount of altitude in a given unit of time. beta (electronic measurement). The current gain of a transistor connected as a grounded-emitter (common emitter) amplifier. Beta is the ratio of the change in collector current to the change in base current when the collector voltage is held constant. beta control range (turboprop engine operation). The range of operation of a turboprop powerplant normally used for in-flight approach and ground handling of the engine and aircraft. Typically the beta mode includes operations from 65% to 95% of the engine’s rated RPM. beta particle (nuclear particle). A particle emitted from the nucleus of an atom during radioactive decay. A negative beta particle is the same as an electron, and a positive beta particle (called a positron) has the same mass as an electron, but has a positive charge. beta tube (turboprop control). A tube in a Garrett TPE331 turboprop engine that extends into the propeller pitch control to act as a follow-up device. It provides proportional movement of the propeller blades with movement of the power lever. bevel gears. A pair of toothed wheels with the teeth cut on a surface at an angle other than 90° to the axis of the shaft on which the wheels are mounted. Bevel gears allow one shaft to drive another shaft that is not parallel to it. bevel. The angle formed by one surface with another surface when the angle is not a right angle. bezel. The rim which holds the glass cover in the case of an aircraft instrument. BFO (beat-frequency oscillator). A variable radio-frequency electronic oscillator used with communications receivers when receiving unmodulated CW (continuous wave) signals. |
