时间：2011-03-11 23:11来源：蓝天飞行翻译 作者：admin 点击：次
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14 CFR Part 1: “A lighter-than-air aircraft that is not engine driven.” balsa wood. A soft, strong, lightweight wood from the tropical American balsa tree. Balsa wood is used in aircraft structure as the core for sandwich-type material. Planks of balsa are cut across the grain and are bonded (glued) between sheets of thin aluminum alloy. The balsa sandwich is strong, lightweight, and rigid. balun. A type of balanced-to-unbalanced radio frequency transformer used in aircraft radio installation. A balun is used to connect a balanced two-conductor antenna to an unbalanced transmission line. bamboo. A tropical plant whose stalk (stem) is made up of strong, lightweight, hollow sections with a tubular shape. The stalks were used as a structural material for some of the very first airplanes. banana oil. Nitrocellulose dissolved in amyl acetate. Banana oil, so called because of its banana-like smell, was used as a dope on the fabric covering of some of the early airplanes. banana plug (electrical component). A device used to make a temporary connection to an electrical circuit. The contacts of a banana plug are springs having the general shape of a banana. These springs press out against the walls of the banana jack to make a low-resistance contact. Banana plugs are installed on the leads of test instruments such as volt-ohm-milliammeters (VOMs). band (electrical frequencies). A range of frequencies acceptable to a piece of electronic equipment. bandpass filter (electronic circuit). An electronic filter that passes a band of frequencies with little attenuation (loss in power), while attenuating, or blocking, all frequencies above or below the band it passes. band-reject filter (electronic circuit). An electronic filter that rejects, or attenuates, a band of frequencies, while passing with little loss all frequencies on either side of this band. band saw (power tool). A form of power saw used to cut wood, plastics, or metal. The band saw blade is a narrow strip of steel with teeth along one edge. The ends of the blade are welded together to form a continuous loop, and the loop passes over two large wheels, one above and the other below the saw table. One of the wheels is driven by an electric motor, and its speed is controllable to allow the operator to match the speed of the blade to the type and thickness of material being cut. For cutting the inside of a hole, many band saws have an attachment that allows the saw blade to be cut in two and an end put through a hole in the work. The ends are then welded back together and the weld ground smooth. bandwidth (electrical circuit characteristic). The difference between the highest and the lowest frequencies in a band of frequencies. bank (airplane flight maneuver). To rotate an airplane about its longitudinal axis, or tilt its wings, by using the ailerons. An airplane is turned by banking it. The lift produced by the wings of an airplane always acts perpendicular to the lateral axis of the airplane. When the airplane is banked, the lift tilts, and its horizontal component pulls the nose of the airplane around in a curved flight path. |
