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Airplane Englres

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AIRPLANE ENGLRES Engines for airplanes are of two types, and these. are (1) the regular stationary cylinder type and (2) the revolving, or gyro type.

The first kind of engines are built like motor boat and motor car engines, only very much lighter for the power they develop. They are made with from four to twelve cylinders; they use carburetors, and have magneto ignition, radiators with water circu lating pumps, and force feed oiling systems.

The Famous Liberty need of a light and powerful airplane engine that could be made in large quantities was felt as soon as the United States got into the war.

The work of designing this engine, or motor, as it was popularly called, was begun in the early part of 1915; by fall work was started on its construction, and in the spring of 1916 the first engine was com pleted. This engine was a that is, it had 12 cylinders and was of the V type. After testing it a second time a more powerful engine was built on the same general lines. It had forged steel instead of iron ones with water jackets which were of pressed steel, and these were welded together by the oxyacetylene process.

After more tests with this engine a third one was built in the spring of 1917; this one was much lighter in weight and all parts of it were designed so that the engine could be produced on a quantity basis. It is shown in Fig. 55.

The final perfected Liberty engine was the most powerful one ever built for airplane work; it de veloped upwards of 500 pounds and its weight was about 800 pounds. This engine was completed at the Packard Motor Car Company's works in Detroit, Mich., on July 3, 1917, and it was rushed to Wash ington, arriving there the next day—the 4th—and this is how it came to be named the Liberty motor.

Both the scupper system of lubrication, that is one in which a projecting spoon on the crank-web throws the oil in the crank-case up on the bearings, and the force feed system was tested and the latter was finally adopted.

Several ignition systems were tried out, but the Delco was the one which proved the most satisfac tory. In this system a small dynamo is used to gen erate the current, and after it is stepped up by spark coils it is passed on to the spark-plugs by distributors.

The Gyro or Revolving $ngine.—In this type of engine, the cylinders revolve around the shaft and, curiously enough, there is no to and fro motion of either the cylinders or the pistons, but each of these turns round a different center. The pistons are connected by their respective connecting rods to a hub and this in turn is fixed to a shaft.

The cylinders, which radiate from the hub like the spokes of a wheel, turn round on it, and instead of the pistons rotating the shaft, the explosions of the fuel charges act on the pistons and these turn the shaft instead. The action of the gyro engine will be understood from the diagram A in Fig. 56, while the engine complete is shown at B.

The Cooling engines are air cooled, that is, the cylinders have paralleled metal rings on them to dissipate the heat exactly like air cooled motorcycle engines. They are, therefore, lighter in weight for the horsepower developed than engines with water-cooled stationary cylinders.

The Use of the the war, airplane engines were not provided with mufflers, but during the war they were used because the noise of the ex haust had to be reduced to a minimum so that the enemy could not hear the planes when they were ap proaching.

for latest airplane engines are equipped with self-starters. As it would not be practical to use storage batteries because of their great weight and since they contain a liquid, starting motors operated by compressed air are used instead.