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Aviation History
1944
1944 - 0611.PDF
MARCH 23RD, 1944 FLIGHT 315 throws out the hand-cranking gear by lifting the hand- crank worm from its complementary wheel. The tubular auxiliary shaft below the crankcase drives the fuel, oil and coolant pumps. All these units are mounted external to the crankcase with their spindles ver tical, and the drive, after initial change of direction by bevel gears, is by trains of spur gears. All the driving elements are mounted in the bottom cover casing and can be detached as a unit; this is shown in one of the detailed illustrations. The lubricating oil pump and filter unit has one main pressure pump, a main scavenge pump (with which is embodied a smaller unit arranged above it serving as a scavenge pump for the supercharger casing), and a scavenge pump for the forward end of the crankcase. With this group are the high-pressure relief valves and two gauze filters. A large pressure filter, of the single felt element type housed in a light alloy cylinder, is mounted on the left of the supercharger casing. Oil at high pressure lubricates the main crankshaft and big-end bearings, the airscrew shaft rear bearing, the reduc tion gear balance arms, and, by a series of pressure jets, the airscrew shaft reduction gears. Reducing valves for the low-pressure system are housed in the front and rear of the crankcase. This low-pressure system is employed "*fc>r the valve-sleeve drives and upper and lower auxiliary drives. The valve sleeves and the small-end bearings of the connecting rods are lubricated solely by oil thrown off by the crank pins. It will be remembered that the supercharger has its separate oil pump driven from the upper auxiliary shaft. This feeds a metered supply to the intermediate and rear bearings of the blower impeller spindle. The outrigger ball bearing of the supercharger, beyond the two-speed clutch unit, depends entirely on oil mist for its lubrication. Oil drained to the crankcase sump is returned by the main scavenge pump to the supply tank by way of the carburettor throttle valves and the jacket of the super charger inlet. The front scavenge pump, drawing oil from the bottom cover casing, does not return it to the tank direct, but instead delivers it to the sump, where it is then dealt with by the main scavenge pump. Cooling.is effected by a 30 per cent, ethylene-glycol mix ture circulated under pressure. Special arrangements arc made to by-pass the radiator when the temperature of the coolant falls, in order to maintain the engine at a suitable operating temperature at altitude. The coolant is circu lated by two centrifugal pumps, each serving one block of 12 cylinders, and the direction of flow can be followed from the circulation diagram. The heated coolant and steam leaving each cylinder block at the upper forward end passes into a centrifuge pipe of electrolytic copper con-' tained in a common annular header tank arranged around the engine nose casing. As the coolant whirls around this tube, the fluid accumulates at the outer wall, whilst any steam escapes through a series of holes in the inner wall into the coolant contained in the header. A spring-loaded valve is provided at the top of the header tank to relieve steam .pressure. At the lower termination of the centrifuge pipe is a thermostatically controlled valve, past which the coolant flows to the divided radiator and thence to the pump, which recirculates it through the cylinder block. Should the temperature of the coolant fall unduly, the thermostat partially or completely closes the valve, thus shutting ofl the radiator and diverting the flow by way of a by-pass pipe directly from the centrifuge pipe to the pump. Cool ant outlet temperatures for various operating conditions range from no deg. C. to 125 deg. C. Owing to the compact rectangular shape of the complete unit, mounting in the aircraft presents only straightforward problems. When installed, all cylinder heads and spark ing plugs are accessible from the sides of the engine enclo sure and all the auxiliaries from above or below. The Sabre, despite its novel design, is probably the highest-powered aircraft engine in full production and fully operational. It fills a very real need in our produc tion programme, and has already made its mark in the Hawker Typhoon. More will be heard of it in the future. NEW DEHAVILLAND ENGINE COMPANY DIRECTORS THEIR many friends in the air craft industry will be glad to learn that at a recent board meeting of the De Havilland Engine Co., Ltd., it was decided to add to the board of directors Mr. J. L. P. Brodie and Mr. Hugh Buckingham. Jhe board previously consisted of Messrs F. T. Hearle, W. E. Nixon, F. E. N. St. Barbe, Major F. B. Halford, and Sir Geoffrey de Havil land. / Mr. Brodie, who becomes director ^^-charge of the engineering divi sion of Hugh Buckingham. J. L. P. Brodie, M.I.A.E. the company, has been closely connected with de Havilland engine development eveq^sfnee the first Gipsy was designed and built in 1926. He became first assistant to Major Halford in 1923 and has been his right-hand man ever since. Mr. Hugh Buckingham, who be comes business director of the company, has been with De Havil- lands as apprentice, engineer, pilot and executive for 18 years. He has recently returned from New Zeal- land, where he inaugurated the sixth De Havilland overseas com pany and built its Wellington fac tory, at which Tiger Moths have been in production ever since. X-RAY CRYSTAL ANALYSIS OF METALS A LECTURE entitled "Modern Views on Alloys and their Possible Application " was given at the 36th annual meet ing of the Institute of Metals held in London by Dr. W. IIume-Rothery, F.R.S. The lecturer dealt with alloys of typical univalent, divalent, trivalent and transition elements, of both scientific and practical interest. He showed that the development of X-ray crystal analysis permitted the determina tion of the positions of atoms in the different crystal structures, and was the first great step forward towards an understanding of the structures of metals and alloys. The study of the X-ray data and the equilibrium diagrams of alloy's enabled a number of factors controlling alloy formation to be discovered empirically. At the same time the mathematical-physicists were encouraged to examine the behaviour of electrons in the periodic field of the crystal lattices of metals, and the results obtained were found to have an immediate bearing on the properties and structures of metals and alloys. As a result of this work one was enabled to look beyond the mere crystal structure, and could begin to understand some of the factors which determined the structure and properties of alloys. In a limited way, from a knowledge of atomic structures, it was already possible to produce alloys with desired structures and properties. WEYBRIDGE BLADES GRADED strength within a given outline may be said to be the salient feature of modern wooden airscrew blades. Such blades have now been -made by the Airscrew Company for many years, and they have come to be taken for granted. It was therefore very welcome for friends of the company to see for themselves the many processes through which the blades go, in a coloured film shown in London the other day. Mr. Titler, chairman of the Airscrew Company, explained that the film was originally made partly for educational pur poses, and partly to enable those workpeople who were tied to one particular job Or process to see the many others that go to the making of an airscrew blade. The film takes one through all the many stages, from the sawing of the spruce planks: to the finished product. The manufacture of the compressed wood (Jicwood) used in the root portion was particularly interesting, as was also the scarfing together of this hardwood root to the softwood blade. But most surprising was, perhaps, the comparative ease with which damaged and broken blades can be repaired.
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