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Aviation History
1957
1957 - 1024.PDF
114 FLIGHT Bristol Olympus BOI.6. Two-spool turbojet. Inspection shows that there is a five-stage tow-pressure compressor, a seven-stage high-pressure compressor, a can-annular combustion chamber with eight flame-tubes, and independent single- stage high-pressure and low-pressure turbines. Overall diameter, 40.875in; overall length as depicted, 152.34in; dry weight, mass flow and pressure ratio, restricted (but see specification for Wright TJ-38 in U.S. section); maximum thrust, 16,0001b (r.p.m. and s.f.c. restricted). This engine will power the Vulcan B.2. Bristol Orpheus BOr.3. Single-shaft turbojet. Reported to be seven-stage compressor, annular combustion chamber and single-stage turbine. Overall diameter. 32.4in; length as shown (with jet pipe), 150in. dry weight, about 750 Ibr mass flow and pressure ratio, restricted; maximum thrust, 4,850 Ib, reportedly with s.f.c. of 0.99. The Orpheus shown is equipped for the Fiat G91. Bristol Orion. Split-compressor, power-limited turboprop. Seven-stage low- pressure compressor, five-stage high-pressure compressor, annular combustion chamber with ten flame tt bes, single high-pressure turbine stage and three-stage low-pressure turbine coupled to the reduction gear and airscrew. Diameter, 41.8in; overall length, 112.3in; dry weight, 3,150 Ib; mass flow, 82 Ib/sec; pressure ratio, over 10:1; maximum take-off power, maintained up to 15,000ft (i.s.a.), 5,150 e.h.p. (4,400 s.h.p. + 1,950 Ib thrust) at 10,000 l-p. r.p.m. with s.f.c. of 0.64; maximum continuous rating, maintained up to 25,000ft, 3,900s.h,p.; cruising rating « 36,OOOft at 350 kt, 3,300 e.h.p. with j.f.e. e>i 0.40. AERO ENGINES 1957 . . . and a related engine, the Zephyr, will shortly be available for com-mercial use. Also well advanced in development is the Orion turboprop, and the B.E.47 is a medium-thrust turbojet. Bristol remain leaders inramjet propulsion and are still producing advanced piston engines, albeit at a low rate. Total employment of Bristol Aero-Engines is roughly 16,000. Themain works is north of Bristol in the Filton/Patchway area. Company- owned research, development and test equipment is very extensive andof impressive ability. The latest establishment is a large-scale facility for high-speed ramjet testing at conditions appropriate to extremealtitudes, and it will shortly come into full operation. A branch factory is located at Sunderland, Durham, and drawing offices are situated inLondon and Cardiff. Bristol have for many years maintained technical collaboration with Wright Aeronautical (U.S.A.) and William H. Allen,a large British gas-turbine and piston-engine (non-aeronautical) firm. The former agreement is of major importance, in that it may lead tothe establishment of Bristol engines in North America with Wright acting as the manufacturer (see Wright, and also the Zephyr engine,below). Bristol hold licences granted by S.N.E.C.M.A. (France) in respect of thrust-reverse mechanisms, and Solar (U.S.A.) in respect ofafterburner systems. In return Bristol engines are being licence-built by S.N.E.C.M.A. (Hercules), and the Orpheus will be licence-produced byHindustan (India), and probably by Fiat (Italy) and in other countries. Olympus. Since 1954 the first-generation, or 100-series, of theOlympus has been in production as the powerplant of the Vulcan B.I medium bomber. After initial development in the period 1950-1953 at9,250/10,000 Ib-thrust, the first definitive model entered production at 11,000 lb dry-thrust as the Olympus 101. In spite of its relative com-plexity, it being the first split-compressor, high-pressure, engine to reach the R.A.F., it has already built up an outstanding record for goodhandling and complete reliability. Early last year an up-rated version of the 101, known as the Mk 102,succeeded the earlier engine on the production line. Clearly fitted with a zero-stage on the compressor, the 102 in consequence has increasedmass flow and pressure ratio, and is rated at 12,000 lb. In turn, the 102 has now been succeeded by the Olympus 103, rated at 13,000 Ib. It ispossible to convert the 102 to operate at 103 rating in the field, a fact which suggests that the increased thrust is obtained by making minorchanges to permit operation at a higher top temperature. Early engines of this first Olympus generation were shipped to Wrightto form a basis for the U.S.A.F. J67 engine. It is also likely that these engines have been operated with Bristol Simplified Reheat, a means forobtaining limited thrust-augmentation, and possibly with complete after- burning jet-pipes. A Canberra fitted with series-102 engines holds the world altitude record, at 65,890ft.Development effort is now centred chiefly on the second-generation Olympus 200-series, of the BO1.6 rating of 16,000 lb. These newengines are of fundamentally later conception than the earlier Olympus, and are designed to incorporate all that had been learnt about gas-turbines up to about 1953. The new compressor is designed to pass far more air than that of the earlier Olympus, and certainly operates at asimilar pressure-ratio, yet it actually has fewer stages and is in all probability lighter. The exterior of the engine is extremely "clean,"and the Lucas fuel-system components are in a compact group beneath the h-p casing. Each rotative assembly in the engine drives one D-sizepump and one oil pump; the oil tank is inside the nose bullet. Typical equipment includes an electric starter geared to the h-p. assembly, aDowty Vardel hydraulic pump and an English Electric/Sundstrand drive. The first of the new family went on to the bed on September 27, 1954.Since that date development has been outstandingly successful, and a full type-test—followed by a magnificent strip—was completed inJanuary of this year. The figure proved at this test was 16,000 lb, then the highest such rating achieved by any engine in the West. Correctedthrusts have reached 17,000 lb for one hour and 17,500 Ib for 30 min, with blading of a type which has since been superseded by laterpatterns. One of the most important applications for the 200-senes engineswould have matched afterburning versions with a Gloster supersonic all-weather fighter. This programme was eliminated in 1955. Withoutan afterburner the BO1.6 is now in full production as the powerplant of the advanced Vulcan B.2, and one of Bristol's primary tasks at presentis the proving of the various new accessories required for this installation. Zephyr. Under this name Bristol Aero-Engines have evolved anextremely attractive commercial turbojet from the military 200-series Olympus. Originally it had been envisaged that the BOl.o-rated civilengine would be the Olympus 510 series, fully rated to give a thrust in the bracket 15,000/19,000 lb. The Zephyr, however, is intended for asomewhat different market. Compared with the military engine it runs considerably cooler. Thisconfers numerous advantages, particularly in the areas of engine hie and noise-level, and also in making possible the achievement of anextremely low specific consumption. The Zephyr also introduces a certain admixture of Orpheus design-features, and differs from theadvanced Olympus in numerous details. Bristol undertook the evolution of the Zephyr in co-operation withWright Aeronautical, and the American company are marketing the engine as the TJ-38 (q.v.). As the specification (see Wright in U.S.section) shows, it is appreciably better than competing engines which are also less-advanced in development. Orpheus. Begun in 1953 as the private-venture B.E.26, this simpleturbojet is now a very successful unit embracing a long line of develop- ment stages. Bristol have succeeded in giving the Orpheus almostunique qualities in its combination of high thrust/weight ratio, low cost and extreme reliability. Its equipment includes a full range ofaccessories, a twin-breech cartridge starter in military engines, Bristol Simplified Reheat (if required) and a reverse-thrust nozzle capable ofexerting on the airframe a net retardation of 1,500 lb. Internal detail may not be released, but an American publisheddescription avers that the engine is a two-bearing design with stress- bearing casings. The compressor is stated to have seven "button-on"stages and the combustion chamber is described as a can-annular design with wrapped and welded Nimonic inner and outer liners housingseparate flame-tubes, the rear ends of the latter carrying the segments of the turbine nozzles. The first prototype ran in December 1954. Only five months laterthe BOr.l special-category rating of 3,285 lb was type tested to enable the engine to power the Folland Gnat in the summer of 1955. Thestandard Gnat engine is now the BOr.2, of 4,520 lb rated thrust, and this engine is in full production for Gnats for the M.o.S., Finland andIndia. India is also likely to manufacture the BOr.2 under a licence- agreement; this will be the first gas turbine to be made in non-CommunistAsia. Most important of the current range of engines is the BOr.3 of4,850 lb-thrust. This unit was fully type-tested earlier this year, and it marks the successful completion of the first generation of Orpheusdevelopment. It is similar to the BOr.2 except for the provision of an increased-capacity fuel pump, which permits higher thrust to be achievedbelow about 10,000ft, a factor of particular importance to the NATO ground-attack machines for which the BOr.3 is intended. It is flyingin the Fiat G91 and Dassault Etendard 6, and is soon to fly in the Breguet 1001. The engine is also scheduled to power the Hispano XC-6or HA-300, the Aerfer Leone, the Fuji TIF-1 and other aircraft. A licence to produce the BOr.3 is held by S.N.E.C.M.A. (France). An offshoot of the first series of Orpheus is a derated, lightweight,long-life unit of BOr.4 rating (4,230 lb). This engine is intended for trainer or transport applications, and it may find its first employmentin the U.S.A. Engines have already been shipped to Lockheed for the CL-329 executive and combat-readiness transport, and North Americancite it as an alternative powerplant for the Model 249 trainer. Later Orpheus are substantially more powerful. Ratings which maybe quoted include those of the BOr.l 1, rated at 5,760 lb and serving as an advanced version of the BOr.l2. The latter, being developed againstMDWP funds for use in NATO light strike aircraft, will have a dry thrust of no less than 6,810 lb, and reheat will raise this to nearly8,000 lb. B.E.47. Earlier this year the Ministry of Supply announced theB.E.47 as a turbojet rated at 6,000 lb thrust, and shortly thereafter a supplementary statement asked that the thrust should be described asbeing "6,000 to 8,000 lb." Bristol have yet to make official reference to the engine. It has been reported unofficially that the B.E.47 is a high-pressure commercial turbojet, of very light weight and high efficiency, stemming initially from the Orion turboprop. Four were once describedas being mounted in nacelles flanking the rear fuselage of the Bristol 200 transport project.
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