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Aviation History
1913
1913 - 0020.PDF
(/QGHT JANUARY 4, 1913. AERONAUTICAL ENGINES. Paper read by A. GRAHAM CLARK before the Institution of Automobile Engineers. Continued from j>agc 1179, December i^th issue.) Some Types Described. TURNING now to the consideration of the details of engine con struction :— The A.B.C. Engines.—The makers of these engines'employ a Fig. 1.—30-h.p. Anzani engine. form of construction which is not at all uncommon in (he United States, in that a range of powers is obtained by varying the number of cylinders and by making the crank-case in sections, which are spigotted and boiled together. This enables the engines to be produced at a lower cost without the sacrifice of good workmanship and manufacture. At the same time, however, it would apper to involve some sacrifice in accessibility, although in other directions provision in this respect is ample in the A.B.C. engine. The ciank-case, of cast steel, is well ribbed on the interior to prevent transverse distortion. The wisdom of mounting the valve levers on the water outlet from the cylinders, which is at a high temperature, is questionable, notwithstanding the large bearing area of phosphor bronze obtained, on account of the difficulty of ensuring the efficient lubrication of the part. The fly-wheel is mounted on a key at the end of the crank-shaft, remote from the propeller. A single cam operates the inlet valves to the two cylinders opposite each crank, and lubricant is carried to the gudgeon-pin through a hole passing up the web of the connecting-rod. If desired, a reduction gear may be fitted and the engines run at a higher speed of revolution ; the ratio employed for the larger engines is 2 to 1 and the reduction gear weighs 28 lb., while that for the smaller sizes is 2J to I, and the weight 19 lb. The Alvaston Motor is one of the few engines extant in which horizontal opposed cylinders are employed, although the advantages of such an arrangement in respect of balance are well known. This engine has an auxiliary exhaust. The cylinders are held together by four lorig vanadium steel rods which pass through the crank-case and through bridge pieces placed over the ends of the cylinders, so that the crank-case is relieved of stress. It will be clear that this ensures a strong, rigid construction, albeit it is open to objection on the score of accessibility, especially in view of the fact that the^e four rods also support the engine upon the fuselage, and hence the engine has to be removed in the event of examination or repair becoming necessary. The Adams Farwell Engine has but one valve placed in the head of each cylinder for both inlet and exhaust ; it is mechanically operated and opens direct into the atmosphere. Thus the valve is opened at the end of the power stroke and remains open during exhaust and inlet periods. During the suction stroke, the fuel is injected into the cylinder in the path of the incoming air. The system is apparently very simple, but there would probably be some difficulty in controlling the supply of petrol, so that the engine would bs extravagant in fuel. The induction of a sufficient charge of air through a valve in the head of the cylinder of a revolving motor is also extremely doubtful. The Albatross Engine employs two cranks at 1800 with each other, while one inlet and one exhaust cam operate the inlet and exhaust valves of all the cylinders, so that the order of firing is 6, 5, 4, 3, 2, I. Auxiliary Fig. 2.-45 and 60-h.p. Anzani engine. Fig. 3.-45 and 60'h.p. Anzani engine. 20
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