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Aviation History
1944
1944 - 0074.PDF
•30 FLIGHT JANUARY 13-ra, 1944 2,200 h.p. NAPIER SABRE valve, liquid-cooled engine with a two-speed supercharging blower. The advantages of the general arrangement from the point of view of installation and maintenance will be obvious from the illustrations. All plugs and cylinder heads are accessible from the sides; coolant, oil and fuel pumps are arranged below the engine, and other auxiliaries are grouped on the top. Carburettor and supercharger occupy the usual position at the rear. Four facings on the underside of the crankcase serve as engine mounting feet. To say the engine bristles with novel features would be incorrect. There are no bristles or trailing appendages on the Sabre. It is a rectangular mass of mechanism, remarkably smooth and compact due to its unique design, and would be better described as being mechanically as full of plums as a pre-war Christmas pudding. Extremely Compact Unit Cylinder bore and stroke are 5m. and 4fin. respectively, giving a total swept volume of 2,240 cu. in. or 36.65 litres. The short stroke enables the width of the engine to be kept down and this factor, in conjunction with the use of sleeve valves, is largely responsible for the compactness of the unit. Two six-throw crankshafts are arranged one above the other in a light alloy crankcase divided vertically on the centre line. The light alloy cylinder blocks bolted to each side of the crankcase each embody twelve fluid-cooled cylinders arranged in upper and lower rows of six. Shallow light alloy pistons working in the opposed cylinders are coupled to the crankshafts by conventional forked and blade-type connecting rods operating on a common crank- pin. At the forward end each crankshaft is geared to a pair of compound reduction gears, and from the front helical-type pinions of these four gears the drive is trans mitted to a large diameter helical gear on the airscrew shaft. This arrangement gives a double reduction of the crankshaft speed. The tubular airscrew shaft is on the centre line of the engine and embodies the pressure oil feed ducts for the constant-speed mechanism of the variable pitch airscrew. The single sleeve valve for each cylinder is of the conven tional type operated by a small crank and a ball connection. Double cranks arranged at 180 deg. actuate the sleeves of vertical pairs of cylinders. Inside the hollow worm shafts are the torsionally resilient shafts which furnish the drive for the medium and high gears of the supercharging blower at the rear end of the crankcase. This component is of the double-entry type. The gear ratio of the supercharged drivels changed by means of opposed conical clutches between which is arranged "JETS" ON THE AIR ON Friday afternoon, following the official release of the news that jet-propelled fighters were in production, Mr. Geoffrey Smith at the invitation of the Canadian Broadcasting Corporation, gave a brief talk on jet propulsion and its im plications. This talk, the first on the subject over the radio, was included in the 6.15 p.m. programme, recorded in Canada, and again issued at 7.45 p.m. on the trans-Canada network, which includes some 40 to 50 stations. A longer talk on trie subject by Mr. Smith over the B.B.C. Overseas service was arranged for to-day (Thursday). AIR LEAGUE MEETING IN the belief that private enterprise must play a large part in British air transport after the war, the Air League of the British Empire hopes to enlist the sympathy and support of the City of London in its plans for stimulating public interest on the subject of air services. A meeting will be held at the Mansion House, under the presidency of the Lord Mayor (Sir Frank Newson-Smith), on Monday next, when the speakers will be the Duke of Sutherland (President of the League), Lord Bennett and Mr. Theodore Instone. " The commercial community," says the League, " has been active in examining the possibilities of air transport and in a double conical male member which is moved hydrau- lically to engage either the medium or high-speed cone. The four-choke, updraught S.U. carburettor supplying the fuel mixture to the supercharger incorporates automatic altitude and mixture enrichment controls. An automatic boost control is also provided, but this is arranged as a separate unit and mounted on the supercharger casing. From the supercharger volute the mixture is fed through .our outlets to cast light alloy manifolds, one for each bank of six cylinders. Exhaust ports are arranged between the banks of cylinders, and each pair is fitted with a single ejector nozzle. The efflux from these nozzles results in an improvement in the aircraft performance. The efficient damping of the exhaust flames by means of these ejector nozzles is a characteristic feature of the engine. Auxiliaries on the upper and lower sides of the crank case are grouped on crankcase covers and actuated by shafts driven from the reduction gears. Above the engine are two B.T.H. duplex magnetos, two distributors, Hey- wood air compressor, Pesco vacuum pump, Dowty hydraulic pump, the airscrew constant-speed governor and an electric generator. Below are the coolant pumps, lubri cating oil pumps and fuel pumps. Combustion-type Starter At the top rear is mounted a Coffman combustion-type starter which drives to the upper crankshaft through the hand-turning gear. At the extreme rear will be noted thr/» cartridge magazine for this unit, which enables five con secutive starts to be effected from the pilot's seat. Lubri cation is divided into high-pressure and low-pressure systems. High-pressure oil is fed to the main and big- end bearings and to the reduction gears, whilst the low- pressure system lubricates the sleeve drives and accessory drives. Ethylene-glycol is employed as coolant, and circulated on a pressure system incorporating a ring-type header tank located around the nose casing and full thermostatic con trol which by-passes the radiator when the engine is warm ing up or if the operating temperature falls for any reason. As long ago as June, 1940, the Sabre passed the Ministry's 100 hours type test with a maximum power out put of 2,200 b.h.p. In its present developed form and in stalled in the Hawker Typhoon, it has a dry weight of 2,360 lb., and produces a maximum of 2,200 b.h.p. at 3,700 r.p.m. At this rating the specific weight per brakf, horse-power is 1.07 lb., a highly creditable figure for-*a liquid-cooled unit. It evokes enthusiasm from maintenance crews, test pilots and combat pilots, and is now in full production. There is no doubt that the Sabre, already a vital factor in the air war, has an important part to play in the impending offensive. outlining suggestions for its organisation. All the signs point to a period of rapid and comprehensive development in the use of aircraft for ocean, continental, internal and feeder-line travel " Most towns throughout the Empire will find themselves involved, and their citizens should be taking an interest now in policies and preparations which will affect their lives and their economic circumstances for many years to come. Upon the Air League rests the duty of awakening people throughout the Empire to theii opportunities." NEW "EXPOSURE SUIT" FOR AIRMEN A LIGHTWEIGHT waterproof "exposure suit" that will •**• increase immeasurably a ditched airman's chance of sur vival in the sea is recommended by a joint committee repre senting U.S. and Canadian Air-Sea Forces, following a three- day series of tests in Canadian Atlantic waters. Volunteer "guinea pigs" were Royal Canadian Air Force crew members from a nearby embarkation point. Some only in regulation winter flying suits, some with the new lightweight exposure suits pulled on over other garb. Results demonstrated the efficacy of the suits in protecting the wearer frqm the sometimes fatal shock of immersion in icy waters, and in greatly increasing his ability to manipulate other life-saving aids.
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