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Aviation History
1921
1921 - 0755.PDF
NOVEMBER 17, 1921 The connecting-rod group consists of a central I-sectionedmaster rod, the big-end of which carries a white-metal lined bronze bearing, and has its shoe united in a scarf joint attached by four studs. Anchored to lugs on the big-end,by hollow pins, are the side connecting rods, which are tubular. Very careful attention has been paid to the lubrication ofthe " Lion " and in many instances difficult problems in this connection have been solved in a most ingeniousmanner. The " Lion " may be started alternatively by electric motor or by hand, the same gear mechanism being used in each case. It is effected by a dog clutch sleeve with off-set faces on the teeth which give an easy cast-off as soon as the engine starts. The sleeve is freely mounted on the tail extension of the crankshaft, and is externally splined to carry—and slide freely through—a worm wheel, which is rotated by a worm spindle carrying the driven one of two . encased spur gears. This spindle extends through the casing at either end, where it is formed to receive a starting handle. When using the electric starter, the cover of the worm spindle casing is lifted off and the motor with its driving spur pinion substituted and secured in place. The " Cub " is a 16-cylindered water-cooled engine, remark- able, not only for its high horse-power of 1,000, but for its general lay-out. The cylinders are arranged in four banks of four, the two upper rows being set at about 50°, whilst the lower ones are at a very wide angle—only a little below the horizontal line, in fact. It is claimed that this arrange- ment has the advantage of relieving crankshaft stresses, whilst the general form is simple and easy to mould into an aeroplane to the best advantage, both aero-dynamically and in connection with the pilot's range of vision, points which should be appreciated by designers. The " Cub " differs in several details from the " Lion." For instance, the separate cylinders of each bank are not united by a head block, but by the overhead camshaft, which operates the four valves of each cylinder.. Two duplex carburettors, each supplying one upper and one lower bank, are mounted at the airscrew end of the engine, and ignition is sup- plied by four magnetos accessibly mounted on platforms at the rear end. A large reduction gear, necessary in an engine of this high power, is provided. Further details, other than those indicated by the accompanying illustrations, we are not at liberty to publish as yet. ROLLS-ROYCE, LTD., 14-15, Conduit Street, London, W. 1. THE name of Rolls-Royce needs no introduction to readers of FLIGHT, and the successes achieved by the aero engines produced by this firm, not only during the late War, but during the past few years of alleged Peace, are world-famous. Three of the aero engines now being manufactured by this firm are the following :—the 270 h.p. " Falcon," the 360 h.p. "Eagle," and the 620 h.p. "Condor." The former was used throughout the War in the famous Bristol Fighters, and the splendid work done by this combination of engine and machine is in itself a recommendation as to its value. The " Falcon " is a 12-cylinder, water-cooled V-type engine, with the cylinders, of 4 ins. and 5 J ins. bore and stroke respec- tively, separate. The normal h.p. of 270 is developed at i,Soo r.p.m.—the maximum r.p.m. being 2,000. An epi- cyclic reduction gear is fitted, giving an airscrew speed of 1,061 r.p.m. The petrol consumption at normal b.h.p. and normal r.p.m. is 18 galls, per hour, and the oil consumption .75 gall, per hour. The weight of the " Falcon," including reduction gear, but excluding radiator, water, oil and fuel, is 705 lbs. The valves are operated by overhead camshafts, driven off the rear end of the crankshaft by vertical shafts. Two magnetos, also at the rear end of the crankshaft, are fitted, and each bank of cylinders has two carburettors, a pair each end of the engine, each supplying three cylinders. The water and oil pumps respectively are located outside, at the rear of and below the crankshaft. The " Eagle " is perhaps the best known of the Rolls-Royge aero engines, since it is the one associated with such historic records as the first direct aeroplane flight across the Atlantic the flights from England to Australia, from England to South Africa, whilst it has been doing excellent work for some time past on the various London-Continental air services. In general design the " Eagle " is similar to the " Falcon," being a 12-cylinder V, with a similar arrangement of cylinders, carburettors, magnetos, pumps and valve gear. The bore and stroke are respectively 4J ins. and 6J ins. An epicyclic reduction gear is fitted, giving a gear ratio of 0.6 or an air- screw speed of 1,080 r.p.m. The normal and maximum crankshaft speeds are 1,800 and 2,000 r.p.m. respectively. The petrol consumption is 25 galls, per hour, and the oil consumption 1 gall, per hour. The weight, with reduction gear, is 900 lbs. The " Condor " is a comparatively recent design, and was manufactured at the request of the Government to meet" the demand for an engine of high horse-power for carrying great weights for long distances. Like the two previous models, the " Condor " is a 12-cylinder V, water-cooled, but in certain details it differs from these engines. The chief difference is in the provision of four valves for each cylinder, these being set diagonally into the four quarters of the cylinder- heads, and are actuated X-fashion by four bell-crank rockers converging upon two cams. There are two carburettors, one on each side of the crank-case, each supplying two groups of three cylinders of its respective bank through six-branched, T-shaped manifolds. The water connections are in four triplicate manifolds Two Rolls-Royce U-cvlinder 755 E 2
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