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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roll threading. A method of forming threads on a bolt or rod by rolling the material to be threaded between grooved rollers. No material is removed when the threads are rolled, as it is when they are cut. root (mathematics). A number which, when multiplied by itself a specified number of times, will produce a given number. root (propeller blade nomenclature). The portion of a propeller blade that secures the blade in the hub. root mean square (rms) (alternating current value). A value used to measure the heating effect of sine-wave alternating current. The rms value is found by dividing one alternation of the AC into an infinite number of instantaneous values. Each instantaneous value is squared (multiplied by itself), and all of the squares are averaged to find the average, or mean, square. The square root is taken of this mean square. The rms value of sine wave alternating current is 0.707 time the peak value of one alternation. One ampere rms has a peak value of 1.414 ( ) amps and produces the same amount of heat as one amp of direct current. The rms value is also called the effective value. Roots-type air compressor. A positive-displacement air pump that uses two intermeshing figure-8-shaped rotors to move the air. rosette weld. A method of securing one steel structural tube inside another. Small holes are drilled in the outer tube, and the inner tube is welded to it around the circumference of the holes. Rosette welds are used to prevent the inner tube moving inside the outer tube. This type of weld gets its name from the fact that the finished welds look like small roses. rosin. A reddish-brown, translucent material left in the process of distilling turpentine from the sap of pine trees. Rosin is used in the manufacture of paints, inks, adhesives, and as a flux for soldering. rosin-core solder. A type of solder used for electrical and electronic work. Rosin-core solder is made in the form of a hollow metal wire, filled with rosin. When the solder melts, the rosin flows out to cover the metal and keep oxygen away from the surface, preventing the formation of oxides. Solder using synthetic rosin for the core is called resin-core solder. rosin joint (bad solder connection). The common term for a bad connection made when soldering electrical wires. Rosin core or resin core solder is used for this type of work, and it is possible for the melted flux to hold the wires together without the solder wetting the wires and making a secure joint. A rosin joint can be prevented by having the wires perfectly clean, and hot enough to melt the solder before the solder is allowed to touch the wires. rotable parts (maintenance supply). High usage, locally repairable components such as aircraft wheels, tires, avionics assemblies, propellers, and built-up engines. rotary actuator. A fluid-power actuator whose output is rotary movement. A hydraulic motor is a rotary actuator. rotary radial engine. A form of reciprocating engine used in some early airplanes because of its light weight. In a rotary radial engine, the crankshaft is attached to the airframe and the crankcase, cylinders, and propeller rotate. Rotary radial engines were popular up through World War I. |
