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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threshold of pain (intensity of sound). The intensity at which sound begins to cause pain. A sound intensity of 150 decibels which is often produced near an operating jet engine is normally considered to be the threshold of pain. throatless shears (sheet metal tool). A floor- or bench-mounted metalworking tool used to cut across large sheets of thin metal. Short cutting blades, operated by a lever, cut across the sheet in much the same way scissors cut across a sheet of paper. throat microphone. A type of microphone used by a person operating in an extremely noisy area such as the cockpit of an airplane. The throat microphone is strapped around the person’s neck so the sensitive pickup rests over the larynx (the part of the throat containing the vocal cords). When the person wearing the microphone talks, vibrations of the larynx vibrate the microphone and produce an electrical signal that can be changed into sound. throttle (aircraft engine control). The control in an aircraft that regulates the power or thrust the pilot wants the engine to develop. throttle ice (carburetor ice). A type of ice that forms on the throttle valve of an aircraft carburetor when the throttle is partially closed. The temperature drop caused by the pressure drop across the partially closed throttle valve, and by the evaporation of the fuel, forces moisture to condense out of the air and freeze on the throttle-valve plate. through bolts (reciprocating engine component). Long threaded rods that extend across the crankcase of an aircraft reciprocating engine to hold the crankcase halves together. The through bolts pass through the cylinder base flanges of one cylinder on each side of the crankcase, and nuts on the through bolts hold the cylinders to the crankcase, as well as holding the halves of the crankcase together. throw (reciprocating engine crankshaft). The offset in the crankshaft of a reciprocating engine to which the connecting rods are attached. Radial engines have only one throw for each row of cylinders. In-line and horizontally opposed engines normally have one throw for every cylinder, and V-engines have one throw for each pair of cylinders. throwaway part. A part of a mechanism designed and built in such a way that it is not economically repairable. When the part fails, it is more economical to throw it away and put in a new one than it would be to repair it. throw-over control (airplane controls). A type of airplane control wheel that may be moved from in front of the left seat to a position in front of the right seat. This is done so the airplane can be flown from either seat. To throw the wheel over, a pin in the control column is released, and the upper part of the column on which the wheel is mounted pivots so it can be moved from one side to the other. thrust (aerodynamic force). The forward aerodynamic force produced by a propeller, fan, or turbojet engine as it forces a mass of air to the rear, behind the airplane. A propeller produces its thrust by accelerating a large mass of air by a relatively small amount. A turbojet engine produces its thrust by accelerating a smaller mass of air by a much larger amount. The mass and acceleration of the air moved by a fan is between those of the propeller and the jet. |
