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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retard. To slow something down or cause it to operate later than it normally does. In a reciprocating engine, the spark that ignites the fuel-air mixture inside the cylinders must be timed so the burning gases produce the greatest amount of push on the piston. When the engine is started, the pistons move slowly, and the spark must be delayed until the pistons begin to move downward. The spark for starting must be retarded. retard breaker points (aircraft magneto component). An extra set of breaker points installed in aircraft magnetos equipped with the “Shower of Sparks” starting system. When the ignition switch is moved to the START position, a second set of breaker points is connected in parallel with the normal breaker points. These points open later than the normal points, and the spark does not occur inside the cylinder until the engine has rotated far enough beyond its normal firing position for these retard points to open. retarded sparks. The timing of the firing of the spark plugs used to start a reciprocating engine. The sparks for starting occur later in terms of crankshaft rotation than those used for normal operation. Retarding the sparks prevent the engine from kicking back when it is being started. retarder (finishing system component). A special thinner used in some types of finishing material, such as lacquer, to slow its drying time. When lacquer or dope dries too fast, the evaporation of the solvents often drops the temperature of the surrounding air enough that moisture condenses out of the air onto the wet finish. This causes the finish to blush, or become dull and porous. Retarder, added to the lacquer or dope before it is sprayed onto the surface, keeps it from drying too fast. When it dries slowly, the temperature does not drop enough to condense moisture out of the air. retentivity (magnetism). The ability of a magnetizable material to retain the alignment of the magnetic domains after the magnetizing force has been removed. Hard steel normally has a high retentivity, while soft iron and electrical steel both have very low retentivity. retort. A vessel used to distill a material. The material to be distilled is put into the retort and boiled. Vapors from the boiling material are picked up from the top of the retort and cooled enough for them to condense back into a liquid. The liquid is collected from the retort in a suitable container. retrace line (cathode-ray tube). The line followed by the beam of electrons in a cathode-ray tube after it ends one line and returns to the start of the next line. Retracing is also called flyback. retract. To draw back or draw up. The landing gear of most modern airplanes can be retracted, or drawn up into the wing or fuselage. retractable landing gear (aircraft landing gear). The type of landing gear that can be folded up into the structure when the aircraft is off the ground. A fixed (nonretractable) landing gear produces a large amount of drag when the aircraft is flying at a high speed. To reduce this drag, the landing gear is retracted, or folded up into the structure. |
