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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hunting (helicopter rotor). The oscillation of a helicopter rotor blade back and forth about its lead-lag hinge as the blade is rotating. hurricane (meteorology). A violent tropical cyclone caused by air flowing into a low-pressure area. Winds blow in a hurricane at a speed of 74 miles per hour (64 knots) or greater. This is a Beaufort force 12 (the highest force). Hurricanes bring rain, thunder, and lightning, as well as the devastating winds. In the northern hemisphere, the air in a hurricane moves in a counterclockwise direction, while in the southern hemisphere, it moves in a clockwise direction. hybrid compressor engine. A gas turbine engine that has both centrifugal and axial-flow compressors. hybrid computer. A computer that has both analog and digital circuits and functions. hybrid spark plug. A fine-wire spark plug that has a platinum center electrode and iridium ground electrodes. hydraulic actuator. The component in a hydraulic system that converts hydraulic pressure into mechanical force. The two main types of hydraulic actuators are linear (cylinders and pistons) and rotary (hydraulic motors). hydraulic brake. An aircraft brake in which the friction is applied to the wheel by a hydraulically actuated unit. The friction is produced in a disk brake when the rotating disk is clamped tightly between friction linings held in a hydraulically operated clamp. hydraulic fuse. A device in a hydraulic system that automatically shuts off the flow of fluid if a line should break. There are two types of hydraulic fuses: one type shuts off the flow after a given volume of fluid flows, and the other type shuts off the flow any time the rate of flow becomes excessive. hydraulic lock (reciprocating engine condition). A condition in which oil drains into the lower cylinders of an engine and leaks past the piston rings to fill the combustion chamber. If this oil is not removed before the engine is started, it can cause serious damage. The propellers on all radial, inverted V-, and inverted in-line engines must be pulled through by hand before they are cranked with the starter to be sure that none of the cylinders have hydraulic lock. hydraulic motor. A hydraulic actuator that converts fluid pressure into rotary motion. Hydraulic motors have an advantage in aircraft installations over electric motors, because they can operate in a stalled condition without the danger of a fire. Hydraulic motors may be of the gear, piston, or vane type. hydraulic powerpack. A small, self-contained hydraulic system that consists of a reservoir, pump, selector valves, and relief valves. The powerpack is removable from the aircraft as a unit to facilitate maintenance and service. hydraulic pump. A fluid-power pump used to force fluid through a hydraulic system. Hydraulic pumps may be engine driven, or they may be operated by an electric motor or by hand. hydraulics. The branch of science or technology that deals with the transmission of power through an incompressible fluid, such as oil or water. |
