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Aviation History
1954
1954 - 1301.PDF
580 FLIGHT, 7 May 1954 THE TWO Rs THE EXE-AND OTHERS The first Rolls-Royce engine to be named after a river, as are the modern turbojets, was this experimental unit, which was notable in having sleeve valves and pressure-air cooling. Its 24 cylinders were arranged in X form, in four banks of six, and the capacity was 22 litres. Rated output was 1,200 h.p. at 4,000ft. The Exe—a rare picture of which appears herewith—was test- flown in a Fairey Battle during 1938, but the project was shelved when it became clear that the company's main productive capacity must be devoted to the Merlin. Another experimental unit related to the Exe was the Pennine, and it may be noted here that in the years preceding the war Rolls-Royce were experimenting with two-stroke as well as four-stroke engines, and continued the compression-ignition experiments started with the Condor. The H layout was also examined. Vulture. THE VULTURE This liquid-cooled engine had its 24 cylinders arranged, in four banks of six, again in the form of an X, and may be considered as two Kestrel-size units with a common crankshaft. It was test- flown in a modified Hawker Henley and was used on operations in Avro Manchester bombers, though various troubles, and the desirability of concentrating on the Merlin and Griffon, led to discontinuance of development. (The basic Manchester airframe, with four Merlins in place of two Vultures, of course, became the splendidly successful Lancaster.) The Vulture was also installed in the Hawker Tornado fighter and Vickers-Armstrongs Warwick bomber. Few details of the engine were ever released, but when it was first described in Flight, in June 1942, it was noted'that the capacity was 2,592 cu in. Maximum power ratings were 1,845 h.p. at 3,000 r.p.m. at 5,000ft in low gear, and 1,710 h.p. at 3,000 r.p.m. at 15,000ft in high gear. Detail construction followed previous practice in that light-alloy cylinder blocks, head and coolant jacket were employed, with "wet" cylinder liners of steel. The crankshaft was carried in seven bearings. Each cylinder had four valves, operated by overhead camshaft, and two sparking plugs; there were two independent screened magnetos. Variable- datum automatic boost control, with two-position mixture control, was used in conjunction with an S.U. twin-choke, down draught carburettor, and there were two vertical air intakes, coupled by a single entry. The two-speed supercharger delivered mixture to two trunk pipes, each feeding two blocks of cylinders. EAGLE THE SECOND The illustrious and wholly fitting name of the first Rolls-Royce aero engine was revived for this, the last of the great line of reciprocating, liquid-cooled units. Reviewing design factors that decided the form of this magnificent piece of engineering Flight remarked: "The initial design project was conceived toward the end of 1942 as the necessity for a higher-powered engine was foreseen. Considerations of aspiration and flame travel set a more or less effective limit of about 6 inches to bore size, and Eagle. with cylinders of this order it has been established that 12 pistons per crankshaft is about the practical limit. Thus a twin-crankshaft engine was necessary, and the disposition of the cylinders in a flat-H followed naturally, since far and away the best installation case is met by this layout. "Sleeve valves were decided upon in view of the fact that they undoubtedly offer advantages over poppet valves from the aspect of maintenance and obviation of adjustment; and whilst no one would be so reckless as to suggest that the poppet valve has reached the ultimate peak of development, it is not far short of the summit and its limitations are very well known." Our description of the engine continued: "The case is split vertically into port and starboard halves of cast light alloy—and a beautiful piece of work it is—with seven bearings for each crank shaft carried in lateral webs axially stiffened by integral inter costal bracing in each half. . . . The front end of the crankcase is double-walled with approximately a 2in cavity, the inner wall housing the No. 1 main bearings of each crankshaft, and the front wall carrying the tail bearings for the timing gears uniting the crankshafts. "Cylinder blocks are also very fine examples of sandcasting technique in light alloy, the upper and lower rows of cylinders on each side being formed in one casting. Each cylinder is ven tilated with three inlet and two exhaust ports, the latter ports of each vertical pair of cylinders discharging to a common pair of ejector stacks. "Sleeve drive is by a worm shaft on each side commonly serving top and bottom rows of sleeves, each shaft running in six split plain bearings. . . ." Early Eagles (I and II) drove a single airscrew, but the Eagle 22 was arranged for contraprops in view of its application to the Westland Wyvern T.F.I deck-landing strike fighter. In M. S. gear the Eagle delivered 3,415 h.p. at 3,500 r.p.m. for take-off. The maximum power rating in M. S. gear was 3,500 h.p. at 3,250ft, and in F. S. gear, 3,020 h.p. at 15,250ft. THE WELLAND Active interest in jet propulsion was first shown by Rolls-Royce during 1938, when a department was established for the design of gas turbines. In 1939 the first projects were put in hand, and by 1940 test rigs for components had been set up. Towards the end of that year the company was making components for Whittle units on behalf of Power Jets, Ltd., and was undertaking the manufacture of turbine blades, casings, pumps and other com ponents. During 1941 a special test plant was installed, with a Vulture to drive the compressors, and at the end of that year, under instructions from the Ministry of Aircraft Production, the company undertook the development and manufacture of Whittle- type turbojets, in conjunction with Power Jets, Ltd., and the Rover company. ^^ The first Rolls-Royce turbojet, known as the WR1, measured 54in in diameter and was designed for a thrust of 2,000 lb. Built primarily to demonstrate that the aircraft gas turbine could be made completely reliable, it ran for some 35 hr. Two examples were built, but combustion trouble was experienced. Early in 1943 Rolls-Royce took over research on the W2B/23 unit from the Rover company, whose engineers had developed straight-through combustion; units of the type were installed in the Gloster E.28/39 experimental aircraft, and in the tails of two Vickers-Armstrongs Wellingtons. The first Rolls-Royce/Whittle
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