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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slide rule (mathematics). A mechanical calculating device consisting of two side-by-side logarithmically graduated scales. The graduations are spaced according to the logarithm of the number, rather than the number itself. Two numbers are multiplied by adding the lengths of the logarithmic scales representing the numbers. Slide rules, which are available in both straight and circular forms, are used to make fast calculations involving multiplication and division and the use of logarithms and trigonometric functions. Mechanical slide rules have been almost totally replaced by electronic calculators that can work all of the problems a slide rule can work, as well as many other types, much faster and with a far greater degree of accuracy. slide switch. A type of electrical switch in which connections are made by sliding a conductor over fixed contacts. slide valve. A valve that opens or closes a port by sliding back and forth over it. Slide valves are used in reciprocating steam engines to open and close the passage into the cylinder to allow steam to enter and leave. slide-wire potentiometer. A form of variable resistor in which the amount of resistance used in a circuit is determined by the position of a contact along a length of resistance wire. The amount of resistance is directly proportional to the length of wire in the circuit. slinger ring (propeller anti-icing system component). A hollow metal ring mounted around the hub of a propeller so that it turns with it. A mixture of alcohol and ethylene glycol is pumped into the slinger ring, and centrifugal force throws the fluid out through short discharge tubes along the leading edges of the propeller blades. The fluid prevents ice from forming on the blades. sling psychrometer. An instrument used to measure the relative humidity of the air. A sling psychrometer consists of two mercury thermometers mounted on a frame with a handle that allows it to be slung around, so air moves across the thermometers. The bulb of one thermometer is covered with a cloth wick saturated with water. As the air blows over it, the water evaporates and lowers the temperature. A chart showing the dry-bulb temperature and the difference between the wet-bulb and dry-bulb temperatures is used to find the relative humidity, in percentage, for these conditions. slip (aircraft flight maneuver). A maneuver in which the aircraft moves through the air sideways, rather than straight ahead. Slipping produces a large amount of drag so the airplane can descend at a steep angle without gaining excessive speed. An airplane is slipped by crossing its controls, using right rudder and left aileron. A forward slip is one in which the aircraft turns its side into the wind, but continues in forward flight. A slide slip is one in which the aircraft continues to point straight ahead, but slips to the side. slip (aircraft propeller specification). Slip, with regard to an aircraft propeller, is the difference between the geometric pitch and the effective pitch. Geometric pitch is the distance the propeller would move forward if it were moving through a solid, and effective pitch is the distance the propeller actually moves through the air. |
