carbon tracking (magneto distributor malfunction). An ignition system malfunction caused by a fine track of carbon deposited inside the distributor of an aircraft magneto.
The resistance of the air inside the distributor at high altitude is so low that it is possible for a spark to jump between the distributor terminals. As this spark moves across the surface of the distributor block, it leaves a thin track of carbon. The resistance of this carbon track is so much lower than that of the material of which the distributor block is made that high voltage leaks through it during normal engine operation. This high-voltage leakage can cause misfiring, loss of engine power, and possible engine damage.
carbon-zinc cell (electrical cell). An electrochemical cell that changes chemical energy into electrical energy. The cell is made of a zinc can filled with a paste of ammonium chloride. A carbon rod is supported by the ammonium chloride in such a way that it cannot touch the zinc can.
Electrical energy is produced as electrons leave the zinc can and travel through an external circuit to the carbon rod. A carbon-zinc cell has an open-circuit voltage of approximately 1.5 volts.
Carborundum. The registered trade name for several types of man-made abrasives. Carborundum is similar to emery (a natural abrasive), and it is used to make grinding wheels. Fine particles of Carborundum are bonded to paper and cloth to make sheets and strips of abrasive materials.
carburetor (reciprocating engine component). A type of fuel metering system used on some reciprocating engines. When air flows into the engine, it passes through a venturi in the carburetor. The venturi produces a pressure drop proportional to the volume of air flowing into the engine cylinders.
The low pressure caused by the venturi pulls the correct amount of fuel through a metering jet, and this fuel is mixed with the air before it enters the cylinders.
carburetor air heater. A sheet metal jacket surrounding part of the engine exhaust system.
Air from inside the engine nacelle or compartment flows between this jacket and the exhaust system component and picks up heat. The heated air is carried through a carburetor heater valve, and when carburetor air temperature is low, can be directed into the carburetor; otherwise it is dumped overboard. Air that flows through the carburetor air heater is not filtered.
carburetor air temperature. The temperature of the air as it enters the carburetor. It is important that the temperature of the fuel-air mixture be kept above the freezing point of water to prevent the formation of carburetor ice, but it is difficult to measure the temperature of this mixture.
By measuring and controlling the temperature of the air as it enters the carburetor, it is possible to keep the mixture temperature high enough to prevent water condensing out of the air and freezing, and at the same time to keep the temperature of the air entering the engine low enough to prevent detonation.
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航空術語詞典 Dictionary of Aeronautical Terms 上
