时间：2011-03-11 23:13来源：蓝天飞行翻译 作者：admin 点击：次
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The correct piston position for ignition varies with the speed of the engine, and the ignition timing on automobile engines is variable; but nearly all aircraft engines have fixed timing. The spark occurs at the same position of the piston regardless of the engine conditions. Fixed timing is a performance compromise, but fixed-timing ignition systems are less complicated than variable-timing systems. ignitron (electrical component). A special high-current rectifier tube. In each cycle of operation of an ignitron tube, an ignitor dips into a pool of mercury, and as it is withdrawn, it creates an arc which produces ionized mercury vapor that conducts a large amount of current. I-head cylinder (reciprocating engine). The cylinder of a reciprocating engine with both the intake and exhaust valves mounted in the head. I-head cylinders are also called valve-in-head cylinders. IHP (indicated horsepower). The theoretical horsepower a reciprocating engine is developing. The horsepower an engine actually delivers to its output shaft is called brake horsepower (BHP). A large amount of power is used to rotate the engine and compress the air in the cylinders. This power is called friction horsepower (FHP). Indicated horsepower is the sum of the brake horsepower and the friction horsepower: IHP = BHP + FHP. illumination. Light energy that falls on a given surface area. illustrated parts list (service information). An exploded view of an assembly in which all of the component parts are laid out so each can be identified. Each part is coded with a letter or number, and a table is included with the drawing, giving the name and correct number for each part and the quantity of the parts needed for the assembly. ILS (instrument landing system). A special type of electronic guidance system used to allow aircraft to land when the ceiling and visibility are too low for a safe visual approach to the runway. An ILS is made up of four basic parts: the localizer, glide slope, marker beacons, and approach lights. The localizer produces a narrow electronic path extending out along the center line of the instrument runway, to direct the pilot laterally as he approaches the runway. The glide slope produces a narrow electronic path extending upward from the approach end of the instrument runway at an angle of approximately three degrees. The glide slope directs the pilot vertically as the aircraft approaches the end of the runway. The marker beacons produce highly directional radio signals to identify the position of the aircraft along the localizer path. When the aircraft is directly over a marker beacon, a distinctive tone is received on the radio, and a colored light on the instrument panel flashes the proper code. The approach lights are a series of high-intensity lights located along the approach path to help the pilot transition from flying by instruments to flying by visual reference as the aircraft breaks out of the overcast. ILS categories. Categories of instrument flight allowed at airports equipped with the following types of instrument landing systems: |
