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Aviation History
1929
1929 - 0363.PDF
FEBRUARY 21, 1929 Table No. 5 SERVICE DATA ON WRIGHT "WHIRLWIND" ENGINES FROM STOUT AIR SERVICES INCOR- PORATED Table No. 8 SERVICE DATA ON 'CIRRUS" ENGINES FROM THE A.D.C. CO. FROM 3 AERO CLUBS Motor Number. 8108 7317 8322 8168 8169 7653 7324 7655 7319 8945 8946 8944 7800 7654 8321 8521 First Second Third Overhaul. Overhaul. Overhaul. Total. School Moths and Hrs. Mins. 271 30 259 25 150 124 124 188 259 308 Hrs. Mins. Hrs. Mins. Hrs. Mins. 259 57 50 50 13 25 49 25 130 336 295 271 338 330 52 24 40 12 43 44 175 25 272 35 167 51 256 26 49 47 Average . . 207 349 42 275 54 293 — 225 — 388 — 620 696 310 124 124 714 708 768 652 36 36 36 272 793 256 49 6203 17 6 35 50 50 57 12 23 44 45 45 45 35 27 26 47 24 Number of machines operated Type Number of engines operated Period covered . . . . . . . . . . 2 Total hours' running Average hours per engine Maximum recorded hours, one engine Average hours between overhauls Maximum hours recorded between overhauls Average man hours for overhaul Average hours' life of parts requiring replacement piston rings, rocker bushes, rear roller races Cylinder barrels Average operating, r.p.m. Average fuel consumption, galls, per hour Average oil consumption, pints per hour 4 Avians 4 £ years 3,083 771 826 280 354 110 300 600 1,780 4-5 1 I am afraid the above rather scattered information is all the actual data that I have been able to collect on the running times of air-cooled engines and their components. To illustrate the difficulty in compiling comparable data, it is interesting to note the difference in man hours shown in the different tables on the same type of engine. A broad review of the charts would show about equal results from British and American engines. SERVICE DATA ON " JUPITER VI 1J DRIVE ENGINES. Table No. 6 ENGINES COLLECTED FROM 20 OVERHAULS ON STANDARD DIRECT- AVERAGE TIME BETWEEN OVERHAULS 336 HOURS Component. Crankcase Crankshaft Valve, inlet Valve, exhaust Valve spring Valve guide inlet . .Valve guide exhaust Piston Piston ring Scraper ring Cylinder .. *Cylinder head Big end bearing Artie, rod bearing . .Master rod Artie, rod Gudgeon pin Artie, rod pinProp, hub Number offper Engine. 1 1 18 18 72 18 18 9 18 9 9 9 1 8 1 8 9 8 1 Number ofReplacements. Nil Nil 11 59 132 8 36 6 164 88 2 Nil 2 2 1 Nil 36 Nil Nil Average LifeHours 1,162 1,162 1,091 683 839 1,060872 813 305 285 960 1,162 872 1,116 1.162 697 1,1621,162 MaximumObserved, Hours to Date.1,413 1,413 1,413 1,015 1,413 1,413[,279 ,413 681 904 1,413,413 ,413 ,413,413 ,413 1,015 1,413 ] ,413 Average Cause ofReplacements. Worn on stem or defective seat Worn on stem or pitted seat. Lost pressures. Scored and worn.Scored and worn. Gudgeon pin bosses-oversize. Oversize gaps. Oversize gaps. Scored barrels. White metal collapsed. Wear.Cracked. Worn in centre. It is somewhat difficult to obtain exact records'of engines over an extended period. Particulars are, therefore, given of three " Jupiter " VI engines which have been installed in the Handley Page " Hampstead " aircraft since 1926 and used on Imperial Airways Continental routes. These are the only engines that have been used in this aircraft during these two years. During the period September, 1926, to September, 1928, the engines ran a total of 4,140 hours, an average of 1.380 hours per engine, and were overhauled twice. With the exception of one cylinder, all the main components, including cylinders, cranks, connecting rods, etc., were used throughout. Table No. 7 SERVICE DATA ON " CIRRUS " ENGINES FROM | THE BRISTOL AND WESSEX AEROPLANE CLUB Number of machines operated . . . . . . . . 5 Type of machines operated . . . . . . . . Moth Number of engines operated . . . . . . . . 5 Period covered . . . . . . . . . . . . 2 yrs. Total hours'operation .. .. .. .. .. 1,450 Average hours'operation per engine .. .. .. 290 Maximum recorded hours on one engine . . . . 403 Average hours' between top overhaul . . . . . . 120 Average hours' between complete overhaul . . . • 360 Man hours for top overhaul . . . . . • • • 25 Man hours for complete overhaul .. . . • • 100 ( ost per running hour, including maintenance, over- haul and spares. . . . . . .. .. .. 1 • Is. Average operating r.p.m. 1.800 Average fuel consumption, galls, per hour . . . • 4 Average oil consumption, pints per hour .. •• 0-5 In a previous paper I have endeavoured to outline the advantages of air-cooled radial engines from the point of view of repairs and operation in extreme climates, etc. I believe I am correct in stating that all these arguments have been fully borne out in practice during the last few years by aircraft using air-cooled radial engines. Constructional Details of Existing Air-Cooled Engines (a) Cylinder Construction.—The forms of cylinder-head construction fall under two main types, either a closed-ended cylinder barrel with head integral with the barrel and an aluminium casting bolted to the head carrying the valves, ports, etc , as in the " Jupiter " engine, or an open-ended cylinder barrel with aluminium head carrying the ports and valve seatings screwed or bolted to the barrel. ' The screwed edition of the latter type used on the '' Jaguar engine, and since employed on most of the American air- cooled radial engines, is, from a theoretical point of view, probably the best design, as it should give a more even heat flow throughout the cylinder. The Bristol Co., up to the present time, have adhered to the closed steel barrel for their large four-valve cylinder of three litres capacity as being a safer proposition and per- mitting the head to be re-serviced after extended periods of running. With smaller bore cylinders, where only two valves are necessary, an aluminium casting open to the explosion has proved very satisfactory. For large-bore cylinders, however, I am of the opinion, that a Y-alloy drop forging should be employed, as with four valves the strength of the head is seriously reduced with a casting. . The Curtiss " Chieftain " engine is the only tested air- cooled engine that I know of which uses an overhead camshaft. 143
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