航空术语词典 Dictionary of Aeronautical Terms 上

时间：2011-03-11 23:11来源：蓝天飞行翻译 作者：admin 点击：次

The Brayton cycle differs from the Otto cycle used in reciprocating engines because the Otto cycle is a constant-volume cycle. See Otto thermodynamic cycle.
braze welding. A method of joining pieces of metal by wetting their surfaces with a molten brass alloy. The brass rod used for braze welding melts at a temperature above 800°F, but below the melting temperature of the metals being joined.
Braze welding differs from brazing in that it does not use capillary action to pull the molten alloy between the pieces of metal being joined.
brazier-head rivet. A thin protruding-head rivet that was at one time popular for aircraft sheet metal construction. Brazier-head rivets have been superseded and may be replaced by MS20470 (AN 470) universal-head rivets.
brazing. A method of joining metals by allowing capillary action to pull molten, nonferrous filler metal between close-fitting parts. When the filler metal solidifies, it holds the parts together.
Brazing differs from soldering in the melting temperature of the filler metals used. Soldering uses filler metals that melt at temperatures below 800°F, and brazing metals melt at temperatures above 800°F.
breadboard (electrical circuit). A device for building experimental electrical circuits that allows the components to be temporarily connected into the circuit, making it easy to exchange components. After a circuit functions as it should on the breadboard, and all the correct components are chosen, the circuit is redesigned into its final configuration.
Many modern circuits are first built on solderless breadboards that allow the substitution of parts without their having to be soldered into the circuit.
break-before-make switch (type of electrical switch). A form of double-throw switch that breaks one circuit before it makes contact with the other circuit.
break line (aircraft drawings). A wavy line or a line containing a series of zig-zags, used to show that a part of the component has been left off the drawing.

breakdown voltage (electrical component rating). The voltage that must be placed across the dielectric in an electrical or electronic component to cause the dielectric to break down and conduct current.
breaker-point bounce. A condition in which the breaker points in an aircraft magneto bounce open, rather than remaining closed when the cam follower moves off of the cam lobe. Breaker-point bounce is caused by a weak breaker-point spring.
breaker points (magneto component). Electrical contacts in the primary circuit of an aircraft magneto that are opened by a cam turned by the engine. The breaker points are timed to open at the instant the ignition spark should occur. When the points open, the primary current stops flowing, and its magnetic field collapses.
The lines of flux from the collapsing primary magnetic field cut across the many turns of the secondary winding and induce a high voltage in the secondary circuit. It is this high secondary voltage that causes a spark to jump across the gap in the spark plug.

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