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Aviation History
1955
1955 - 1752.PDF
9 December 1955 delivery casings, from which it is extracted by a scavenge pump in each sump. All the labyrinth seals are sealed by low-pressure delivery air with the exception of the last bearing (No. 8), which requires second-stage h-p air. The accompanying drawing indicates the manner in which the various air supplies are distributed to perform sealing, or pressure-balancing, functions. Cooling of the first turbine disc is accomplished by a throttled feed from the h-p compressor delivery, the flow passing through drillings in the hub of the disc and out along both sides. The second disc is cooled by leakage under the inter-turbine labyrinth and also by second-hp-stage air brought to the rear face of the turbine; additionally, founh-hp-stage air is used both to seal the disc and help to cool its front face. Most of these cooling flows were ducted through external pipes; in later engines a con- siderable degree of cleaning-up is apparent. Fuel is supplied to a pair of Lucas C-type pumps driven through the bottom radial strut of the high-pressure delivery casing. Lucas were also responsible for the control unit, which is a full-range flow control accepting the delivery from both pumps. From the control unit a single delivery line leads to the primary circumferential manifold, the main flow to the 10 injec- tors being distributed through individual rigid pipes. Accessories on the B.O1.1 were necessarily rudimentary, but a variety of drives could have been taken out through the radial struts in either the intermediate casing (from the 1-p system) or the delivery casing. The single electric starter pro- jects in an ungainly manner from the latter, driving through a Bendix engaging mechanism and constant-mesh gear. This completes the description of the B.O1.1, the most recent 875 Convair F-102 all-weather intercepter, and other types, but development seems to have become sluggish at about 12,000 lb thrust. Recendy the U.S.A.F. stated that no production orders would be placed for current J67s, and it is doubtful if the engine will succeed in the face of competition from the P. and W. J75 and G.E. J79. The next British Olympus was the BO1.1/2B, which, although it appears to be aerodynamically similar to its predecessors, represented a major advance in design. At this stage the Olympus was getting near the flight stage and it was natural that considerable rearrangement should be undertaken to rationalize and clean up the whole powcrplant. Typical of this revision, it can be seen, has been the relocation cf all accessory gear trains in the intermediate casing, the hot delivery casing being unsuitable for such purposes. This change, in turn, resulted in noteworthy reduction in the size of the drive coupling, and die overall weight of the engine came out at no more dian 3,520 lb. Improvements were also made in the combustion system. This mark of Olympus first ran in December, 1951, with a rating of 9,750 lb. With slight modification it became the Olympus Mk 99 (the first Olympus flight engine in Britain) and, derated to 8,000 lb owing principally to airframe limitations, it flew in an English Electric Canberra B.2 test bed on August 5th, 1952. The pilot was W/C. Walter F. Gibb, D.S.O., D.F.C., assistant chief test pilot at Bristol, who has since handled a great deal of Olympus work, assisted by Godfrey Auty. On May 4th, 1953, the same Canberra, flown by Gibb, estab- lished a new world altitude record for aeroplanes, at 63,668ft. Meanwhile, the Olympus 99 was re-engineered for installation Flows of oil and air through an early Olympus, shown schematically. The various paths taken by the air, for both cooling and pressurizing purposes, require no further explanation when the diagram is studied in conjunction with the text. The oil circuit is depicted in the lower part of the drawing, the chain-dashed line representing pressure oil and the plain dashed line the scavenge pipes. Olympus for which such information may be published. Evidently almost identical, but representing a slight difference in build standard, was the B.O1.1/2A. This unit was prepared to suit the immediate needs of me Wright Aeronautical division of the Curtiss-Wright Corporation, of Wood-Ridge, New Jersey. In October 1950, it was announced that this company had entered into an agreement for technical collaboration with the Bristol Aeroplane Company, and that it had acquired develop- ment and production rights for a new gas turbine which is now known to have been the Olympus. By so doing Wright hoped to re-establish their previous pre-eminent position among America's engine-builders widiout having to build up a full staff capable of tackling a large gas turbine from scratch. Bristol accordingly shipped specimens of the BO1.1/2A to die American company. The rating of this engine was 9,750 lb, but it is recorded that, on a cold New Jersey day around Christmas, 1950, Wright succeeded in obtaining a spot figure of 10,000 lb—believed to have been the first five-figure thrust achieved by a basic British engine, wimout any augmentation. As the TJ-32 (Wright designation) the basic Bristol engine was steadily Americanized during 1951, and it flew in a fixed nacelle under a B-29 test bed. , . During this year Wright decided to effect a complete redesign in order to beat the competing Pratt and Whitney engine, rhey aimed at achieving 15,000 1b thrust, and development contracts for an engine of this rating, designed J67, were then placed by the U.S. Air Force. The mass flow was increased to approxi- mately 230 lb/sec, and the gas path was accordingly completely rearranged, die combustion chamber case being split into top and bottom halves, as was done with the later Bristol engines. It was intended that this engine should eventually power the in the Vulcan, and it began bench trials in diis form—designated Olympus 100—in die summer of 1952. Flight clearance was granted in January 1953 at a conservative initial rating of 9,250 lb, and die second prototype Vulcan flew widi four Olympus 100s the following September. This engine had a rated thrust more representative of the engine's true capability. Thus ended the first series of Olympus. It is obvious that considerable aerodynamic revision was a feature of the next series, of which the first was the BO1.1/2C. Compared with its predecessors, the mass flow can be seen to have been markedly increased, and to take out the enormous shaft power required for compression die diameter of die turbine was increased well beyond the point at which the combustion chamber casing could be slipped off the rear of the engine. Accordingly, a completely new casing was developed, without strengthening ribs, in top and bottom halves bolted together like the compressor casings. A complete de-icing system was developed, air being tapped off from the delivery casing, controlled by a Teddington gate valve, and ducted along the right-hand side of the engine to heat the intake and entry guide vanes (the latter, of course, now being fixed). Stator anchor bolts are visible around the casings of the compressors, indicating a continuance of me original blade locking. No accessories are mounted in the hot zone of the engine, the drives being all taken through the intermediate casing. The electric starter lies snugly off the bottom of this casing, adjacent to the single Lucas D-type fuel pump and the Serck fuel-cooled oil cooler. A large generator is mounted in the nose cone, driven off the front of the 1-p compressor, cool air being induced at the front of die bullet by an annular inducer at the rear. Another expected change from the earlier engine is the employment of
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