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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bus tie breaker. A circuit breaker used to connect two electrical bus bars. bushing. A type of friction bearing consisting of a removable cylinder made of some material, such as bronze, that has a low coefficient of friction. The bushing is pressed into a hole, and it is reamed to a size that fits the shaft with the correct amount of clearance for lubrication. Some bushings are made of Oilite, a porous bronze material that is impregnated with oil and requires no additional lubrication. butt fusion. A method of joining two pieces of thermoplastic material. Butt fusion is done by heating the ends of the two pieces until they are in a molten state and forcing them together before they cool and harden. butt joint (welded joint). A type of welded joint in which the pieces of metal to be joined are placed so their edges touch, but do not overlap. The edges of both pieces of metal are melted, and filler rod is added to form a bead between the two pieces. butt rib (wing rib). The rib at the inboard end of a wing panel. butterfly tail (airplane control surfaces). A type of tail configuration used on some models of the Beech Bonanza. A butterfly, or V-tail, has two fixed surfaces and two movable surfaces, which produce aerodynamic forces to rotate the aircraft about its vertical and lateral axes in the same way as the three fixed and three movable surfaces used in the conventional inverted T-tail. butterfly valve. A flat, disk-shaped valve used to control the flow of fluid in a round pipe or tube. When the butterfly valve is across the tube, the flow is shut off, and when it is turned parallel with the tube, the obstruction caused by the valve is minimum, and the flow is the greatest. Butterfly-type throttle valves are used to control the airflow through a reciprocating engine fuel metering system. buttock line (aircraft lofting term). A line used to locate a position to the right or left of the center line of an aircraft structure. Buttock lines, or butt lines, are identified by their distance in inches to the right or left of buttock line zero, which is the center line of the structure. Buttock line 12R is 12 inches to the right (facing forward) of the center line. Butyl. The trade name for a synthetic rubber product made by the polymerization of isobutylene. Butyl withstands such potent chemicals as phosphate-ester-base (Skydrol) hydraulic fluids. butyrate dope. An aircraft finishing product having a film base of cellulose fibers dissolved in a mixture of acetic and butric acids. Butyrate dope, also called CAB (cellulose-acetate, butyrate) dope, contains, in addition to the film base, the necessary solvents, thinners, and plasticizers to make it bond to the fabric and shrink it. Butyrate dope has, to a great extent, replaced nitrate dope because it is less flammable than nitrate. Buys Ballot’s law (meteorology). A law of meteorology that helps understand the circulation of the wind. Buys Ballot’s law states that if, in the northern hemisphere, we stand with the wind striking us at our back, the center of the low-pressure area, around which the wind is blowing, is ahead of us and to our left. |
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