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Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
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points of oxygen and nitrogen (the main constituents of air). Liquid air is an extremely cold, faintly bluish,
transparent liquid. For air to remain in its liquid state, it must be stored in a special insulated container.
If liquified air is allowed to boil, the first gas released is nitrogen, and then, when the nitrogen has
all boiled away, the oxygen turns into a gas. Both nitrogen and oxygen are produced commercially by
boiling liquid air.
liquid-cooled engine (reciprocating engine). A reciprocating engine that uses a liquid, such as water or
ethylene glycol, to remove excess heat. Much of the heat energy in the fuel burned in an engine is wasted
and must be carried away from the engine, or it will cause damage.
In a liquid-cooled engine, the liquid coolant circulates around the cylinders in jackets and absorbs
heat. This absorbed heat is carried outside the engine in the coolant, and as the coolant passes through a
radiator (a liquid-to-air heat exchanger), the unwanted heat is given up to the outside air.
liquid crystal. A type of liquid whose molecules can be arranged by electrical charges in such a way that
polarized light cannot pass through a film of the liquid. Liquid crystal is used in the displays for calculators,
clocks, watches, and in the new generation of aircraft instruments.
liquid nitrogen. Nitrogen that has been changed into its liquid state by lowering its temperature. Nitrogen
remains in its liquid state under standard atmospheric pressure when its temperature is kept at –195°C
(78°K) or lower.
liquid oxygen, LOX. Oxygen that has been changed into its liquid state by lowering its temperature.
LOX remains a liquid if its temperature is kept at –183°C (90°K) or lower.
Lissajous figures. Figures formed on the screen of a cathode-ray oscilloscope that show the relationship
between the frequency of sine wave signals being applied to the horizontal and vertical inputs. If the
frequency and phase of the two sine wave signals are the same, the Lissajous figure will be in the shape of
a circle.
If the frequency of the sine wave signal applied to the vertical input is two times that of the signal
applied to the horizontal plates, the Lissajous figure will be shaped like a figure eight (8).
liter. A metric unit of volume. One liter is the volume of one kilogram of pure water at a temperature of
4°C under standard atmospheric conditions. One liter is equal to 1,000 cubic centimeters, and it is the same
as 1.0567 quarts in the English system of measurement.
lithium. A soft, silvery, highly reactive, alkali-metal chemical element. Lithium’s symbol is Li, its atomic
number is 3, and its atomic weight is 6.939. Lithium is the lightest of the metals, and it is used as an
ingredient in batteries and as an alloying agent for other metals.
lithium cell (primary electrical cell). A lightweight, high-energy primary electrical cell, useful because of
its long shelf life. A lithium cell uses lithium metal as its negative electrode and a gas dissolved in an
electrolyte as its positive electrode. Lithium cells produce an open-circuit voltage of between 2.8 and 3.6
volts, which is about twice the open-circuit voltage of most other primary cells.
lithium grease. A semisolid lubricant made of lithium salts and fatty acids. Lithium grease is highly water
resistant and is useful for low-temperature lubricating applications.
lithometeor (meteorology). The general term for dry particles suspended in the atmosphere. Lithometeors
include dust, haze, smoke, and sand.
lithosphere. The outer crust of the earth. The lithosphere is made mostly of rock and is considered to
extend down for about 50 miles.
litmus. A water-soluble powder that changes its color when acted on by an acid or a base (alkali). Litmus
turns red when it is acted on by an acid and blue when acted on by a base.
litmus paper. An indicator paper, used to determine whether a solution is acidic or basic (alkaline). Litmus
paper is made by soaking a piece of absorbent paper in a solution of litmus powder dissolved in water.
When blue litmus paper is wet with an acid solution, it turns red, and when red litmus paper is wet with an
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
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alkaline solution, it turns blue.
Litzendraht wire (litz wire). A special type of conductor, used for carrying high-frequency alternating
current. Litz wire is made of fine strands of insulated wire, woven together in such a way that any
individual strand occupies, at some time, every position in the cross section of the conductor. This special
type of construction gives litz wire its low opposition to the flow of high-frequency AC.
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航空术语词典Dictionary of Aeronautical Terms 中(111)
