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Aviation History
1914
1914 - 0121.PDF
AERO ENGINES AT PARIS SHOW, 1913. Continued Chenu Motors. The models exhibited closely resemble the conventional car- engine. The cylinders, which are in pairs of cast iron, with the jacket cast integral with the body, are placed vertically on an aluminium crank-case. They have exceptionally large inlet and exhaust valves, which are arranged on opposite sides of the engine, while ample water spaces are provided, reaching well down the cylinder barrel. The lubricating pump, driven off the centre of the camshaft, is placed in a sump formed in the base of the crank- chamber, which contains sufficient oil for 10 hours running without replenishing. Bosch, double ignition is fitted, one plug in each cylinder being at the side near the inlet valve, and the other over the exhaust valve. This form of ignition would appear to be essential on these engines, which run at extremely high speed, on account of the slow ignition of the charge due to the shape of the combustion chamber. A double half compression device is fitted to facilitate engine starting, as this is especially necessary where the reducing gear is fitted. The weights of the reducing gears, which are supplied with any of the three smaller engines if desired, are 22 lbs. for the four- cylinder engines, and 31 lbs. for the six-cylinder 100 h. p. engine. Two carburettors are fitted to the two six-cylinder models ; whilst the standard thrust bearing provided permits the engine to be used for A tractor screw or a propeller. This firm have introduced a new model of the same dimensions and general construction as the old four-cylinder 65 h.p. engine which was entered as a 50 h.p. last year, but which, by the use of lighter reciprocating parts, larger valves, &c, is now able to run at a much higher normal speed. The maximum revolutions of the 65 h.p. engine is i,8oo per minute, but the 90 h.p. engine may be from page 98.) over the crank-shift on ball-bearings, and have rounded projections upon their periphery. The inlet pipes are arranged radially on the near side of the engine. The cylinders of the fixed engines are made separately of steel, and have copper jackets electrolytically deposited on them, which are provided with expansion bellows along the barrel to allow for the differences in the coefficients of expansion of steel and copper. The inlet and exhaust-valves are of the concentric type, and are 250 b.p. Chenu engine. run at 2,300 revolutions per minute. The torque curve is the same for both of these models, until after a speed of revolution of about 1,500 per minute is attained. The largest engine, 250 h.p., is intended for use on dirigibles and several have already been fitted to the Astra Torres VI, XIII, XV and XVI, besides other aircraft. Clerget. The new 7-cylinder 80 h.p. rotary engine was exhibited, in addition to which a 50-60 h.p. rotary engine, two vertical 4-cyiinder water-cooled engines of 50 and 100 h.p., and a 200 h.p. engine of similar design to the 100 h.p., but with the cylinders arranged in vee fashion were also shown. Two carburettors and two magnetos are used with the vee engine, and one camshaft situated on the centre line of the engine operates both valves in the two groups of cylinders, as is usual on this type of engine, but the camshaft is so arranged that it may be moved axially for the purpose of varymg the period of opening to inlet or exhaust. On the rotary engines the cylinders are of steel, machined out ol the solid billet, and attached to a steel crank-case. Both inlet and exhaust-valves are arranged in the head, and are mechanically- operated by push-rods and rocking-levers suitably balanced for centrifugal force by counter-weights attached to the ends of the rocking levers. The exhaust-valves are placed on the leading side of the cylinders in the direction of rotation, so as to receive the maximum cooling effect, whilst the inlet and exhaust-valves in each cylinder are disposed in such a manner that their centres lie on the helix along which the head of the cylinder moves when the machine is in motion. The valve gear is operated by means of special eccentric discs, which are mounted 80 h.p. 7^cyllnder Clerget engine. mechanically operated through rocking - levers, the push • rods actuating the inlet-valve being inside the tubular rod which controls the action of the exhaust-valve. These valves are situated in the centre of the cylinder-head, so that the shape of the combustion' chamber is nearly hemispherical. SIForced lubrication and cooling is provided by pumps placed, as is also the magneto, at the end of the engine. De Dion Bouton. This engine, an 8-cylinder of 80 h.p., still retains the principal features that have always characterised it, and was illustrated in FLIGHT for November 2nd, 1912. It is air-cooled by forced induc tion from a fan attached to the end of the crankshaft, which draws air around the cylinders through an aluminium casing fitted over the 900 vee between the two groups of cylinders. The cylinders are secured to the aluminium crank-case by long bolts passing through bridge-pieces fixed over the head of the cylinder. The con necting rods, two of which are attached to each crank, and the pistons are of steel, and in order to allow of the corresponding cylinders of opposing groups to be set opposite each other, the feet of the rods for the cylinders on one side of the engine are forked and fitted with bronze bushes on the crank. The big ends of the rods for the opposing cylinders fit over the bushes between the fork, so that whilst the forked set of rods function in the usual manner, the big ends of the other rods work on the exterior of the bush. On account, however, of the extremely small relative motion and the large surface provided, it is stated that very little wear takes place, even after a long period of working. The propeller is driven off the end of a single camshaft, which operates the inlet valves directly through tappet gear, and the ex haust valves through push rods and rocking levers. The valves are arranged in a pocket in the cylinder on the side nearest the centre of the engine, the exhaust valve being placed over the inlet. The three intermediate bearings of the crankshaft are lined with bronze, but to the extreme ends of the shaft ball-bearings are fitted. The oil sump is of sufficient capacity to last for 7 hours at full speed, and the weight given in the table includes that of two exhaust collectors. Demont. The designer of this engine has for a number of years been engaged in the construction of various rotary motors, one of which was built as far back as 1896. The engine is a six-cylinder 300 b.p. double acting, air-cooled, rotary engine ; which has, as is to be expected from such a combination, an extremely low power/weight ratio—073 lbs. per horse-power. Double acting engines are not of 121
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