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Aviation History
1928
1928 - 0617.PDF
31 J.W.Y 5, 1928 THE BEARDMORE " CYCLONE" AND " TYPHOON THE " CYCLONE " THE Beardmore " Cyclone " engine is a six-cylinder-in-lineunit of 8| in. by 12 in. bore and stroke, and at its normal speed of 1,350 r.p.m. develops 850 h.p., or with a largercarburettor 950 h.p. A similar engine of the inverted type, so mounted that thecylinders project downwards from the crank-case, is also produced, called the " Typhoon." Though a very similar type has been produced in which theDiesel principle of compression ignition is employed and which runs on crude oil, the " Cyclone " and " Typhoon "run on petrol. As a matter of fact, their compression ratio is on the low side, being only 5-25 to 1. The charge is firedin the normal way by magnetos, the Watford C.6 S.M. being the standard type employed. The weight of the " Cyclone " power unit is only 2,150 lbs.(975-2 kgs.) " dry"—i.e., without radiator, fuel,'or cooling water. The weight-power ratio is 2-4 lbs. (1-08 kgs.) perbrake horse-power. The fuel consumption also, as demon- strated on the trials, is remarkably low, so that for flights oflong duration the " Cyclone " should be a very economical proposition. The petrol consumption is 0-48 lb. (0-2 kg.)per brake horse-power per hour, and the oil consumption 0-01 1b. (0 004 kg.). Taking round figures, the total consumption on full throttlerunning is 0-5 lb. (0-22 kg.) per horse-power per hour, or at the maximum power of 950 b.h.p. is 475 lbs. (215-4 kgs.)per hour. Thus the weight of the engine plus the fuel it consumes in one hour is 2,625 lbs. (1,190-7 kgs.), but for10 hours the figure is only 6,900 lbs. (3,130 kgs.), which is remarkably low for an engine developing 950 b.h.p. The great advantage of this engine is, of course, its simplicityof design, and the fact that a low speed is possible without recourse to gearing down of the propeller, which is a commonsource of trouble on other engines. On the " Cyclone " the propeller is attached directly to the crankshaft. The sim-plicity of design naturally makes for reliability and low maintenance costs. Another point in its favour is the lowhead resistance. THE " TYPHOON ' The " Typhoon " is an inverted edition of the " Cyclone"engine. It develops between 800 and 900 b.h.p. at approxi- mately 1,350 r.p.m., the six cylinders also being arranged inline. Generally speaking, very little has been done with theinverted type of engine for aircraft, yet it would seem to be the logical type for this purpose. In the case of the Beard-more " Typhoon " the inverted position is certainly the obvious one. To get the line of thrust somewhere near itsproper position, it would be necessary to have the tall cylinders projecting upwards a very considerable distance,offering resistance and obstructing the view of the pilot. By inverting it, the thrust line is kept in its natural position,the cylinders hang down in the front of what has in any case to be a deep fuselage, and the nose, owing to the small widthof the crank-case, can be narrowed down so as to obstruct the view forward as little as possible. The use of a small number of large cylinders in the" Typhoon " necessarily makes for an engine having a small number of working parts, each of them relatively robust,and should therefore make for reliability and long life. Further, it makes for economy, for large cylinders, otherthings being equal, give somewhat higher thermal efficiencies than do small ones, and a small number of cylinders simplifiesthe problem of distribution and makes it easier to obtain uniform output and efficiency from all cylinders. " Cyclone " Number and arrangement of cylinders.—6 in line, vertical.Cooling.—Water. Bore.—8f in. (219 mm.). Stroke.—12 in. (304-8 mm.). Compression.—5-25 to 1.Power.—Normal, 850-950 h.p. at 1,350 r.p.m. Airscrew.—Direct on crankshaft. Ignition.—Two Watford C.6.S.M. magnetos.Weight.—2,150 lbs. (975-2 kg.) dry. Specific weight—2-4 lbs./b.h.p. (1 -08 kg./CV.). Length o.a.—6 ft. 8J in. (2-04 m.).Width o.a.—2 ft. 11 in. (0-9 m.). Height o.a.—5 ft. 1J in. (1 -56 m.). Fuel consumption.—0-48 lb./b.h.p./hr. (0-21 kg./CV./h.). Oil consumption.—0-01 lb./b.h.p./hr. (0-004 kg./CV./h.). Note.—The "Typhoon" varies from above only in certainminor details. 565
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