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Aviation History
1922
1922 - 0009.PDF
type. The master rod is always assembled in the left-hand side of the engine when the crankshaft is turning clockwise, so that the maximum pressure on the small rod will come in a line through its gudgeon-pin hole, wrist-pin hole and the crank-pin centre. These rods are steel drop-forgings, heat- treated and finished all over. The upper bushing is " non- gran " bronze, and the lower bushing is bronze-backed babbet, which is riveted in the rod and cap with brass rivets. The lower end of the small rod is forked, and carries two non-gran bronze bushes. Two 52-mm. Duplex Ball and Ball car burettors are fitted. Each venturi tube feeds three cylinders through a fan-shaped manifold, which is open to the three cylinders and carburettor ""without partitions. The two carburettor air intakes are interconnected with sheet- aluminium conduits, which can be led to the outside of the fuselage. Ignition is furnished by two high-tension single-spark, 12-cylinder magnetos of the polar inductor type, driven through flexible couplings from the vertical shaft. There are two sparking-plugs per cylinder, connected to the magnetos by cables enclosed in aluminium tubes. The plugs are located at right angles to the centre line of the block and diametrically opposite. One magneto is wired to the " exhaust " plugs, and the other to the "inlet" plugs. These magnetos are equipped with a special switch which gives battery excitation for starting when the magnetos are fully retarded. The cooling water is circulated by means of a centrifugal pump located at the lower end of the lower vertical shaft. This pump is of the double shrouded type, having an alumi nium impeller with the intake on the lower side. Water is drawn from the radiators, entering the pump through the cover, and, after being discharged from the pump, is directed to the lower end of the water-jacket in each cylinder through tapered manifolds. The water surrounds the cylinder sleeves, and enters the cylinder heads through holes drilled in the latter, and circulates around the ports and passes out at a point between the valves on each cylinder into a tapered manifold. From this manifold the water passes back to the radiator. The water pump is equipped with a deep-grooved radial bearing, which takes the thrust of the rotor caused by the suction of the water pump. It is also provided with a suitable stuffing gland to prevent leakage. Lubrication is by pressure feed from an oil pump located in the lower half of the crank-case and driven as previously described. The gear pump forces oil into a manifold, which directs the oil into the bottom of each main bearing. The main journals in the crankshaft are plugged, and receive oil through three equally-spaced Tioles in the journal. The oil then travels through a tube inserted from the journal to the crank-pin in the connecting-rod bearing. Tubes are also fitted in the articulated wrist-pin to carry oil from the connecting-rod bearings to the bearings in the small connecting rod. The cylinder walls and wrist-pins are lubricated by splash, whilst the upper vertical shaft is fed by pressure from a duct leading from the first main bearing. Oil is piped from the anti-propeller end of the crank-case from the last-men tioned duct to the camshafts through the foot of the first camshaft bearing. Each camshaft is drilled at each bearing, so that oil may find its way into the inside of the hollow camshafts, allowing oil to lubricate each camshaft bearing under pressure. The camshaft bearings do not receive the full oil pressure, as the holes in the first crankshaft main journal are so arranged that the camshafts receive index- feeding twice per revolution of the crankshaft. Oil from the camshaft bearing drains back into the front sump through the camshaft drive-shaft housings to the front gear-case, and lubricates the ball bearings which carry the camshaft drive-shafts. It also lubricates the lower vertical shaft, which is carried in two bronzs bushings surrounded by a _pocket of oil. The oil from the connecting-rod bearings and main bearings is drained into the front and rear sumps, to be drawn into the suction pumps through tubes connecting the pump with either end of the engine. The suction pumps then force oil into the oil reservoir below the oil partition. The pressure pump draws the oil through a truncated cone screen, thereby ensuring clean oil to be forced into the main bearings. A pressure-regulating adjustment is provided on the cover of the oil pump. This cover is also arranged for connecting an oil cooler in series with the outlet of the suction pump. The petrol system which is used in the high-speed 'planes equipped with the CD-12 engine is laid out as follows :—A double opposed petrol pump, which is driven through worm gearing at approximately one-tenth of the vertical drive-shaft speed, and operates the pistons by means of a cam working in a slot in the connecting rod between the two pistons. This arrangement provides a crank-case in the pump which has a constant volume when the two pistons are reciprocating. Oil under pressure is supplied to this crank-case, and a suitable relief valve is provided to maintain a predetermined pressure. This oil pressure seals the pistons against petrol leakage, and lubricates the piston walls. The pump forces petrol to the carburettors, a small header tank being putHn the line to dampen out pulsations. A relief valve is placed in the line to maintain a constant pressure to the carburettors. This relief valve overflows to the main tank. The principal characteristics of the CD-12 are as follows :— Low comp. High comp. Rated h.p. Normal r.p.m. B.h.p Comp. ratio •• Weight, dry „ with oil tank, water radiator ,, per b.h.p., dry ,, ,, with oil Petrol consump., lbs./hr. b.h.p./hr. Oil consump., lbs./hr. .. b.h.p./hr. Bore .. • .. Stroke Overall length ,, width height tank, •• •• and 375 2,000 335 5-7 Low comp. Lbs. etc. * * 1.82 2-4 192.5 05 3.00 0.00E Ft. 4 2 2 400 2,000 405 6.1 Lbs. 700 922 High comp Lbs. 1-75 2.27 202.5 0-5 324 0.008 Ins. 4i 6 Ins. 8* 41 11 Married On December 22, at St. Woollos, Newport, HENRY WOLFERSTAN BECK, R.A.F., was married to MATILDA GENEVIEVE LYNE. On December 6, at Littleham Church, Exmouth, G. T. W. BURKETT, M.C. (formerly Australian Artillerv and Lieut. R.A.F.), only son of Mr. G. Burkett and Mrs. Burkett, of Melbourne, Australia, was married to ADELAIDE HENRIETTA, elder daughter of Rev. F. W. Tracy and Mrs. Tracy, of 14, Morton Crescent, Exmouth. Major HEREWARD DE HAVILLAND, D.S.O., M.C., third son of the late Rev. C. M. de Havilland, Rector of Crux Easton, was married at the Embassy Chapel, Madrid, on December 9, to MARY PROCTOR SWABY, only child of Mrs. J. de Solla, of Madrid, and the late Dr. William Percy Swaby. The marriage took place at St. Augustine's Church, Johannesburg, on December 13, of SYDNEY MACKENZIE SPROAT and GLADYS MARY MEESON. TO be Married The engagement is announced of ANTHONY CONNING KIL- BURN, late R.A.F., of Murrah Hall, Troutbeck, Cumberland, youngest son of Mr. and Mrs. C. Conning Kilburn, of Broad- stone, Dorset, formerly of Calcutta, and MAUD, eldest daughter of Mr. and Mrs. C. TOPPIN, of The College, Malvern. Deaths ANTHONY PEER GROVES, second son of Margery and William Peer Groves, R.A.F., of 2, Chester Gate, London, N.W. 1. and Salford, died on December 17, from pneumonia. LESLIE GRONOW WOOD, Flying Officer, R.A.F. (" SPLINTER "), second son of Dr. and Mrs. A. T. Wood, died on December 19, of illness contracted in Egypt. l>
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