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Aviation History
1967
1967 - 2210.PDF
7 International, 16 November 1967 805 SPEYS INTERNATIONAL By KENNETH FULTON ROLLS-ROYCE TODAY is a very different company from thatwhich launched the RB.163 Spey turbofan in 1959. In thecourse of the intervening eight years, especially the past five, the organisation of R-R has been radically reformed, rationalised and brought in line with the .most modern and progressive of management practices. More than £4.5 million has already been spent on a massive new computer centre at Derby, the services of which are available to all sections of the company throughout Britain. There is a much finer aware- ness of the importance of meeting the needs of the market as distinct from producing technically the best engines. Design decisions large and small are now firmly based on their cost effectiveness, and all new products stand or fall on their anticipated contribution to profits. In all its phases the Spey has been the major commodity by which these advanced tech- niques have been introduced. In its origins this engine extends back close on a decade to the Rolls-Royce RB.141 second- generation turbofan for the de Havilland DH 121 short/ medium-range transport ordered by BEA in February 1958. The RB.141, later given the series name Medway, was con- ceived as a family of high-economy twin-spool turbofans having broad application in short- and medium-range airliners, and covering the 12,000lb to 15,0001b thrust bracket. Designed to take advantage, in modern form, of R-R's turbofan experience with the Conway RCo.12, the engine in its basic configuration comprised a five-stage l-<p compressor (fan), 11-stage h-p com- pressor, a cannular combustion system with ten flame-tubes, and two-stage h-p and 1-p turbines. The by-pass ratio was 07:1, and pressure ratio 16.75:1. Prime variants were the 11,8001b RB.141-3 (with four-stage 1-p compressor) for the DH 121, and the 14,0001b RB.141-11 for the projected Sud- Aviation Caravelle VIII. Detail design of the Medway had started early in 1958, but within 18 months major revisions to the DH 121 specification resulted in the thrust requirement being reduced to just under 10,0001b. Despite the fact that manufacture of the first batch f RB.141 s was then well advanced, it was decided that a smaller engine was necessary: further de-rating of the Medway would have incurred too great a penalty on the operating economics of the aircraft. Design work on a new tunbofan, the RB.163, therefore started in July 1959. In essence the RB.163 was an aerodynamic scale-down of the basic RB.141 design, but with the opportunity being taken to ntroduce advances in engine technology achieved during the two years since the inception of the larger turbofan. The major cycle parameters were again optimised to meet the propulsion leeds of the short-to-medium-haul sector, but with the engine sized in its initial version to meet the thrust requirement of ^ DH 121. The turbine entry temperature and pressure ratio remained as for the RB.141, but in optimising the take-off/cruise thrust 'atio and reducing the exhaust noise-level to below that requiring a suppressor, the b.p.r. (by-pass ratio) was raised to inity. This necessitated the last stage of the 1-p compressorbe ing omitted, and a further stage being added to the front °i the h-p compressor. These modifications also involved slight changes to the relative proportions of the two turbines. The hnl design of the engine, however, remained essentially an aerodynamic scale-down of the Medway. In the design and development of the RB.163 it was vital to ch up on the original DH 121 programme time-scale and to 'ttract the maximum benefit from the time, money and experi- Latest civil variant of the Spey which has just completed its official l50hr type test is the Mk 512 with take-off ratings of 11,9601b and 12,0001b according to installation. The engine is seen here in the port pod of the Trident 2, demonstrating its accessibility ence already vested in the RB.141. It was decided, therefore, to continue with development of the Medway at its full planned rate until such time as RB.163 engines and rigs became available. Thereafter testing was to be at a reduced rate until sufficient RB.163s were built to undertake all necessary development. The first RB.141 ran in November 1959 and a total of nine of these engines ultimately completed some 1,600 hours' bench time. This tactic enabled valuable operating experience to be gained with RB.163-type components for embodiment in the new engine while it was still in course of design and experi- mental manufacture. The links with RB.141 experience were further strengthened by giving the Medway design and develop- ment teams responsibility for the RB.163. In the broadest possible sense, the RB.163 was conceived as a consolidation of R-R's extensive commercial turbine engine experience, then amounting to an unrivalled 16 million flying hours. For this reason the temptation to achieve performance gains by utilising temperatures, stresses and materials in advance of the company's existing civil experience was deliberately avoided: compared with previous R-R engines, the design of the Spey is conservative. Even so, it was intended that- the engine should provide significant improvements in specific weight, thrust and consumption, and in noise-levels, over earlier turbofans. Civil Spey Variants Spey RB. 163-1 As the basic configuration of engine, this first ran on December 31, 1960. Intended for the DH 121 (later named the Trident), this version carried the brunt of the Spey civil development programme. A total of 19 experimental and 11 pre-production engines were built to assist in com- pressing the early development phases and so regain the original Trident time-scale. Flight testing of the Spey in the inboard
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