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Aviation History
1958
1958 - 0289.PDF
Taken at R.A.F. Waddington, these photographs show engines due for routine overhaul (left) and the port intake of a Vulcan (right). tor located inside. The bullet was itself heated by circulation ofhot air, and because of its large diameter this arrangement has been referred to as "the biggest heated pitot in the world." As a result ofthis work, the Olympus 100 series engines were fully cleared for operation in severe icing conditions and thus represent the higheststandard of anti-icing protection. Meanwhile, engines delivering the full 11,000 lb (dry) thrust ofthe Mk 101 were installed, and flew for the first time in July 1955. These were among the most powerful production engines flyinganywhere at that time. Later the same year the second and third production aircraft took the air, the first six machines beingused initially for development purposes, particularly including the armament, radar and other equipment. Apart from XA 889 alreadymentioned, the only machine used for development connected with the engines was the fifth production aircraft, XA 893, which wasassigned the task of proving the A.C. electrical system which is being introduced on later aircraft. An essential part of thissystem is the Sundstrand drive, licence-produced by English Electric at Bradford, which enables the alternator to be drivenat the required constant speed over a wide range of engine r.p.m. Events have shown that this policy of intensive developmenton early aircraft, which was carried out by the manufacturers, A. V. Roe and Co., Ltd., the government establishments, andBristol Aero-Engines in full co-operation, was very sound. It has paid handsome dividends by ensuring that even minor troubleswere overcome before delivery of the aircraft to the Royal Air Force. As a result the Vulcan, in the words of the Under-Secretaryfor Air, "has probably had the minimum amount of teething trouble of any aircraft introduced in the R.A.F. over the lastten years." Bristol Olympus. All Olympus engines are split-compressor turboiets, each compressor spool being driven by a single-stage turbine. The basic Olympus 101 has a six-stage l-p. spool and an eight-stage h-p. spool; later 100-series engines have a zero-stage on the l-p. spool. Ten flame-tubes are fitted in the annular combustion chamber. Overall diameter is approximately 40in and length about 150in. Mean figures for production 101 and (in brackets) 102 engines are: weight, 3,615 1b (3,793); thrust, 11,O34lb (12,009); specific consumption, 0.817 (0.811). During 1956 the Vulcan was in the hands of Boscombe Downfor a full assessment of handling and performance, and this resulted in full clearance being given to the aircraft and the Olympus 101engines for Royal Air Force service. After completing the normal contractor's trials, the first aircraft for the Royal Air Force washanded over during the summer of 1956. The large amount of flying which was achieved, starting immediately after the aircraftwas received by the service, is an eloquent testimony, not only to the trouble-free nature of the aircraft, but also to the enthusiasmof the operating aircrew and ground crews (this first aircraft carried out over 200 hours' flying in its first four months of service). During the summer of 1956 the R.A.F. received a number ofVulcan B.I aircraft powered with the 11,000 lb-thrust Mk 101 engine. Most of this first batch of Vulcans were assigned to No.230 Operational Conversion Unit at Waddington, and have since been engaged upon the training of Vulcan crews. In October 1956,however, one aircraft (XA 897) was picked to fly on an extensive tour of Australia and New Zealand. This tour was marred by the tragic accident at London Airportat its conclusion (Flight, February 1, 1957), but was other- wise extremely successful. It had been carried out to a pre-arranged schedule, the aircraft visiting Melbourne, Sydney and Adelaide on the outward journey and Brisbane and Darwin on thereturn, in addition to the airfields at Christchurch and Ohakea in New Zealand. A point-to-point record was established betweenAdelaide and Christchurch, the section between Hobart (Tas- mania) and Christchurch being covered at an average speed of 634 m.p.h. En route to Australia the aircraft flew non-stop fromAden to Singapore and from Singapore to Melbourne, taking off heavily loaded under tropical conditions. ' During the tour, which covered approximately 30,000 miles,the engines behaved literally perfectly, and the only attention which was given to them was two routine inspections involvinglittle more than visual examination and cleaning of filters. As a result of the inspections of engines used in the two proto-type Vulcans, the initial overhaul period for the Olympus 101 was fixed at 200 hours. It was agreed that an intermediate flame-tube inspection was not necessary. Meanwhile, further aircraft were delivered to the Royal AirForce during the early part of 1957, and the amount of flying carried out increased correspondingly. A feature which was intro-duced at an early stage was a cruising-speed governor, to maintain the engine rotational speed at a constant value during climbs andunder altitude cruising conditions. It is well known that, when a turbojet is operating at less than maximum governed r.p.m., aslight variation in engine speed tends to occur with change of altitude, and the introduction of the cruising-speed governorrelieves the pilot of the necessity for watching the engine speed and adjusting the throttles under these conditions. With early Olympus 101 engines there were cases of failure ofthe starter quill-shaft as a result of the shock loading when the drive was taken up during starting. Although it had no particu-larly serious consequences, this was an embarrassing type of failure because it occurred when the aircraft was otherwise readyto taxi out and take off on a mission. Accordingly, a revised drive was introduced, and this cured the trouble. Only a relatively small number of aircraft were delivered withthe 11,000 lb Olympus engine before the Olympus 102 (described below) was introduced, with a dry rating of 12,000 lb. However,before an adequate number of aircraft powered by the Olympus 102 had been introduced into service, No. 83 Squadron enteredthe annual bombing competition of Bomber Command using the Olympus 101-powered aircraft. This was the first officialannouncement of the formation of No. 83 Squadron, the first operational unit to receive the Avro Vulcan. Based at Wadding-ton, No. 83 Squadron was formed from crews which had com- pleted their training with No. 230 O.C.U. at the same station. In July the results of the competition—which was flown fromR.A.F. Marham at the end of June—were announced. Although recently formed, and competing with numerous other squadronsusing well-established aircraft, the Vulcan squadron succeeded in winning the Laurence Minot Trophy, awarded to the mediumbomber squadron gaining the highest total of marks in bombing and navigation. The squadron also won the Sir Philip SassoonTrophy for the best navigational results throughout the competi- tion. The Commanding Officer of No. 83 Squadron, Wing Com-mander A. D. Frank, D.S.O., D.F.C., won the individual awards both for navigation and for bombing and navigation together. Competing aircraft made, cross-country flights of five hours'duration, at the end of which simulated radar-bombing attacks were made from altitudes of between 40,000 and 50,000ft on pre-selected targets. Throughout the competition not one Vulcan failed to complete a scheduled flight, which is an indication of theexceptional reliability of both the airframe and engines at this early stage of their career. Turning now to the Olympus Mk 102, it should be noted that thisengine is similar to the 101 but has an additional zero-stage on the low-pressure compressor. This has the effect of increasing themass-flow and pressure ratio, and consequently the thrust. How- ever, it also results in alteration of the engine handling charac-teristics, and on early flight tests it was found that the handling of the 102 engine at altitudes above 45,000ft was not all that couldbe desired. The engine's behaviour was perfectly satisfactory over
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