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Aviation History
1913
1913 - 0075.PDF
JANUARY 18, 1913. AERONAUTICAL ENGINES. [/OCHT Paper read by A. GRAHAM CLARK before the Institution of Automobile Engineers. (Continuedfrom page 48.) Mercedes Daimler Engines.—There are three different sizes Of these engines manufactured, namely, 70, 100 and 240-h.p., the last-mentioned being employed for dirigible work. The 70-h p engine is similar in general arrangements to the 240-h.p. excepting that the water pump and magneto are placed at the end of the engine and driven off the crank-shaft, the former direct and the latter through gearing, and that the inlet manifold from the car burettor is taken over the top of the engine, while the suspension is from the top half of the crank-case. It will be seen from Figs. Q and 10, that an overhead cam-shaft driven by bevel gear is employed on the 100-h.p. engine, thereby with to o W Q T> M u C W s a A 6 o CO a w a a •a O CM I M bo bo G Q a 6 o bo avoiding the use of long push rods which become necessary the arrangements for both the 70 and 240-11.p. engines. The method of circulat - ingthewaterinthe 70-h.p. and the ioo-h.p.|(Fig. io> would appear to lie capa ble of improvement, since the discharge from the pump is taken through the cylinders in suc cession, and hence the last cylinder to receive the water will be at a higher temperature than the first. In the 240-h.p., Figs, 11 and 12, the water is delivered to branch pipes attached to the tops of the cylinders. Fox Motors.—These are operated on the two- stroke cycle, and the particular class of engines manufactured for aero nautical purposesembody what is termed a " fourth port." The three port type of engine resembles the ordinary two-stroke engine used in this country, excepting that the connection be tween the cylinder and the crank-case during cylinder induction is by way of a port cut in the wall of the piston beneath the rings and a chamber in the wall of the cylin der, while the main inlet port is formed in the cylinder wall and is covered by the piston when at the bottom of its stroke. The merit of the " fourth port" lies in the fact that it is go constructed that the di rection of the air which alone passes through it (and which is, in addi tion, passing through the main inlet port), is up wards towards the interior ol the piston, so that when the cylinder induction commences, the mixture from the crank-case is preceded by the pure air thus ad mitted. The claims made are that greater economy in fuel consumption and greater power are ob tained, but it is difficult to see how the latter is effected unless the engine is working inefficiently when on the three port system. (To be continued). u "Si a w a. -G* ! _bo 75
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