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Aviation History
1955
1955 - 1753.PDF
876 FLIGHT BRISTOL OLYMPUS . . . high-energy ignition. The two annotated photographs give aclear indication of the manner in which the various assemblies in this engine have been arranged. In October, 1952, an early BO1.1/2C went to the U.S.A.,where it has since been investigated by Wright Aeronautical. In June of last year the engine first flew in the hard-workingCanberra B.2, and in December of that year the production ver- sion, designated Olympus 101, was type tested at 11,000 1bthrust. At this rating the Olympus 101 must have since been delivered in quantity for the Avro Vulcan B.I medium bomber,since this is the only announced current production application. The 101 turns the scales at 3,650 lb—a figure surprisingly lowerthan that for the roughly comparable J57 (4,200 1b). Actual specific fuel consumption on production engines is generally ofthe order of 0.79 lb/hr/lb at maximum thrust at sea level; the bottom of the loop has been quoted by Bristol's chief engineeras being 0.75 at 8,000 lb thrust. This excellent figure has been of inestimable value to the Avro designers in enabling them tobeat every one of the Vulcan's design targets. We visited the Bristol Engine Division earlier this year, as theguest of Dr. Stanley G. Hooker, who took over as chief engineer from Mr. Owner in 1951, and has since been principally respon-sible for the development of all Bristol gas turbines. On the occasion of our visit we wrote of the Mk 101 production enginein the following terms: — "It is fascinating to observe on the test bed the speed relation- ships between the two compressors of the Olympus. At low speeds the ratio is about 2:1, the low-pressure compressor min- ing at 2,500 r.p.m. and the high-pressure at 5,000 r.p.m.; but the ratio progressively adjusts itself so that the maximum thrust figures, respectively, are 6,500 and 8,500 r.p.m. Dr. Hooker mentioned that at minimum self-sustaining speed a mere 10 1b of thrust is generated, though it is not possible to accelerate away from this speed. Continuous cruise output is 9,600 lb, and the engine can be acceleiated from idling to its full take off thrust of 11,000 lb in 5 seconds. "High thrust, fuel economy and acceleration are qualities fer- vently to be desired in a long-range all-weather fighter, and it would come as no surprise if the Olympus were to find a very important application in a machine of that class. Questioned on the suscepti- bility of the two-spool layout to supersonic conditions, Dr. Hooker said that it was suitable for operation over a wide range of intake con- ditions, though for supersonic flight relatively low compression ratios would have to be used. The engine has been cleared to use wide-cut gasoline or kerosine. "Among the graphs exhibited to illustrate Olympus performance was one showing power curves at the beginning of a test run and at a late stage, when dirt had been deposited on the blades from the atmosphere, to the obvious detriment of performance. Once an engine has been washed through with paraffin and water, however (this is done at idling speed), thrust is quite restored."From the production viewpoint the Olympus is surprisingly good. In final erection, the engine is stood on its nose and every-thing is built up from the front to back, the engine being gradu- ally lowered into the floor on a hydraulic ramp. In developmentof the production engines blade trouble has been conspicuous by its absence, and handling remains nothing short of superb. Dr. Hooker himself delights in showing just how violently the enginecan be treated without protest. From the BO1.1/2C, or 101, the next step is the BO1.11. Thisengine has been described as having greater thrust than the 101, and it was this improved rating which was instrumental in push-ing the world's aeroplane altitude record to 65,876ft—again in the same stalwart Canberra, flown by Walter Gibb—lastAugust 29th. It seems that this again finishes a chapter in the story of thisfine engine, because the latest Olympus are so far ahead of their progenitors as to be virtually different engines. The only officialpronouncement about them is a passing reference to the BO1.6, described as "the most advanced mark of Olympus." In theU.S.A. this engine has been referred to as being in the 15,000-lb- thrust class; one report states that "the Olympus 106 and all suc-ceeding engines are 15,000 to 16,000 lb units intended for super- sonic application." Presumably the 106 is the production BO1.6.No details of the progress of these engines may be published, •beyond the fact that the first was placed on test just one yearago, on December 14th, 1954. Flight trials will begin next year, with a pair slung in nacelles under the fourth Avro Ashton, whichBristol have employed in Olympus development for over a year. Finally, brief reference may be made to afterburning. It hasbeen unofficially reported that Bristol have conducted protracted investigations into obtaining partial thrust augmentation byinjecting fuel into the tailpipe from a simple assembly, the pro- pelling nozzle being fixed at the non-reheat area. Known asB.S.R. (Bristol Simplified Reheat), this can no doubt be applied to the Olympus. For full-blooded afterburning, Bristol havesought the co-operation of Solar Aircraft, of San Diego. No details of the arrangement may yet be published, apart from stat-ing that the control system is likely to work upon the neat and effective "Microjet" principle, outlined in our previous issue. It would seem, however, that a fully reheated Olympus willcertainly be made available, capable of very high thrust. In this connection, it is logical to couple the idea of an after-burning Olympus with an announcement made earlier this year by the Under Secretary-of-State for Air, Mr. George Ward. Hesaid that orders had been placed for 18 prototypes of an entirely new all-weather fighter, to be developed from the Javelin by theGloster Aircraft Company. It is now known that the power units of this obviously supersonic aircraft will be advanced modelsof the Bristol Olympus. Altogether, then, the Olympus is one of the most significantengines from Britain that we have yet produced. It has been instrumental not only in planning some of our most importantaircraft programmes, but also in enabling Bristol's Engine Divi- sion (to be Bristol Aero Engines, Ltd, as from the end of thismonth) to build up an outstanding staff of experienced engineers. Had it not been for the Olympus it is doubtful if the companycould have brought forth the Orpheus turbojet so amazingly quickly. Recent foreign reports also indicate that there isanother turbojet, of extremely advanced conception, on the draw- ing boards. But the Olympus will always be the bedrock uponwhich Bristol turbojets are based. THE AERONAUTICAL BOOKSHELF "Aircraft Today," edited by John W. R. Taylor. Ian Allan, Ltd., Craven House, Hampton Court, Surrey. Illustrated. Price 9s 6d.T HE idea which prompted Mr. Taylor to bring out this annual,the first edition of which was warmly welcomed when it appeared last year, was to keep the technician, the spotter, thebusinessman and the youngster informed about the latest important developments in the world of flying. With such contributionsas "What do we know about Russian aircraft?" "The New London Airport," "Swan Song of the Flying-boat?" "How Near is Push-button Warfare?" "Shortening the Take-off," "The Future of Military Air Transport" and "The Adventure of Test Flying"—all by recognized authorities—he has again succeeded. The curio-collectors will rejoice in the hitherto unpublished photo-graphs of a startling Claire Vance Scout and of a D.H.9A with Vickers oleo landing gear, Frise ailerons and Handley Page slotsfor slow flying experiments in 1927. But perhaps the most widely acclaimed feature of all will be the four pages of R.A.F. squadronmarkings in colour. . - "The World's Famous Racing Aircraft, 1925-1953," bv John W. Underwood. Aerolit, P.O. Box 1349, Glendale, California, U.S.A. Illustrated.N EVER did Hollywood heroes design more fantastic aircrafton the backs of old envelopes than those illustrated in this picture book. The fact that the author has shown only one wing and one undercarriage leg in the head-on and plan-view linedrawings makes them look as unbelievable as their names—Goon, Toots, Chief Oshkosh, L'il Monster, Shoestring and all the othersin which brave pilots with no visible means of aerodynamic sup- port have won the Goodyear and other U.S. Trophy races. A Sabre looks out of place among aircraft like a Corsair withthe outer halves of its wings replaced by flat metal fences. This is, nevertheless, an interesting record of aircraft that, for themost part, have contributed little but excitement to aviation pro- gress. Exceptions are the 1934 Comet racer and the SchneiderTrophy seaplanes with which, as British readers will be gratified to see, the book opens. The results of some of the U.S. NationalAir Races since 1929, the Schneider Trophy Contests, and the progress of the World Speed Record from 1927 to 1953 arelisted on the last three pages. "The Wooden Horse," by Eric Williams, M.C. Collins, St. James's Place, London, S.W.I. Illustrated. Price 8s 6d. ""THOSE engaged in making lists of Christmas presents might*- keep in mind this new, illustrated children's edition of a book which had a remarkable success when it was publishedsome six years ago. Although expurgated in its new form, the book retains its atmosphere of suspense and conveys mostvividly the spirit of the prisoners in Stalag-Luft III, most of whom were R.A.F. aircrew. The illustrations—sketches anddiagrams—are profuse and complement the text very well.
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