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Aviation History
1954
1954 - 2020.PDF
1954 jf tha 1 received an enquiry from Rolls-Royce for two dozen Vokes- po! erth windscreen wipers at the then price of four guineas each, and :rom then onwards enquiries and orders followed, r.olybourne, Hants. C. G. VOKES. p.R. Cameras AS a very enthusiastic reader of your very excellent journal, I am taking this opportunity to query whether you are correct in your statement in the article on "MilitaryAircraft, 1954," under the section "Reconnaissance Aircraft," in^lvhich you state that a single F.24 camera is fitted to the Glgefer Meteor F.R.9. This is liable to give many people both at home and abroad AWRITTEN statement circulated by Mr. Duncan Sandys, Minister of Supply, in Parliament on June 28th shows the extent of the work now being carried out on the suppression of noise from aircraft engines of all types. Mr. Sandys said: "Aircraft noise, I well recognize, is becoming an increasingly serious and urgent social problem, to which some solution has got to be found and found^iuickly.'' A number of public organizations and universities are concentrating on the problem, and the aircraft companies themselves are also taking immediate steps to reduce noise nuisance from ground running. The financial allocation for this work for 1954 is, as the statement shows, 150 per cent up on that for 1953. Below, we publish in full the remainder of the statement: — "The problem is being tackled from a number of different angles. The main effort has been concentrated on jet engines. [ "A leading firm of engine-makers has been given a substantial •contract by the Ministry of Supply to carry out an extensive pro gramme of studies and experiments. This includes a detailed fcnalysis of the noise of a jet engine operated with various alter native types of nozzle on an open-air test bed. The nozzles which pre being tested include toothed, corrugated, convergent- Kivergent, and fishtail types. Promising results have been obtained •from toothed and corrugated nozzles and further studies are being •nade to decide the optimum shapes for these types* I "Since it is known that the by-pass engine causes less noise than •he conventional jet engine, a special study of the by-pa§s engine •n relation to the noise problem is being carried out to determine •he relationship between noise, jet velocity and temperature. The Kfect on noise of injecting water into the jet stream is also being Investigated. I "Two other engine companies are working under Ministry of Kupply contract on the development of silencers for piston engines •ised in helicopters. Some of the types of silencers which are •>eing tested are showing encouraging results. Work is proceeding •in the task of lightening the weight of these silencers and of •educing their adverse effect upon engine power. "The Ministry of Transport and Civil Aviation is experimenting ^ith the construction of a brick baffle wall at London Airport, •his wall is shaped to accommodate the forward part of a large Kivil aircraft, with the object of reducing noise in certain direc tions when engines are being run on the ground. However, •esults are not yet entirely satisfactory and the investigation is •eing continued. "After obtaining competitive tenders from appropriate firms, Bie Ministry of Supply has placed a contract for the design of two wpes of mobile ground mufflers. One of these is to be suitable •r single-engined aircraft and the other for multi-engined aircraft. The first muffler of the single-engine type is expected to be ready •>r(experimental testing in the course of the next few months. • "One firm of aircraft manufacturers has been experimenting •ith portable screens which are placed round the aircraft while the •Jgine is being run up. Some reduction of noise has been obtained mi further screens are on order. In addition, four other aircraft •anufacturers are employing a firm of consulting engineers to •vise them on the use of specially designed pens for muffling the •and of aircraft whose engines have to undergo running tests on • ground. Another firm, on its own initiative, is building a pair • mobile ground mufflers to its own design. S 'in addition a series of tests are being carried out by the College I Aeronautics under contract from the Ministry of Supply. f' thampton University, with some financial support from the istry of Supply, is carrying out valuable laboratory work with • object of obtaining a fuller understanding of the nature of • flow. Manchester and Edinburgh Universities are also under- F ng important fundamental research on the origin and nature • >et noise. I Expenditure by the Ministry of Supply on this problem during • current financial year is estimated at about £100,000, com- f'-'d with £40,000 last year. In addition the Ministry of Trans- flP- and Civil Aviation expects to spend about £20,000 on the 57 a very wrong impression of this country's progress, as the F.24 is an obsolete camera, quite unsuitable for side oblique photography in a Meteor. For some considerable time now MetejjrF\R.9 machines have been fitted with the F.95 cameras-developed for low-altitude photography, a fan of three,,,^lrneras for port, starboard and forward being mounted in the nose of the aircraft, the pilot having full control of all three cameras. These cameras have been mentioned in your journal on twelve occasions since the start of 1953, and are also in use with several friendly air forces in other countries. W. B. HAKES London, N.W.2 study of this problem in the present year. Figures of expenditure by firms and universities on their own account are not available." The whole subject of aircraft noise is much in the public eye —or perhaps it should be "ear"—at present. Particular attention has been directed to noise from helicopters, and this subject was discussed in our leading article last week. Many will welcome the news that experiments are in progress—with initially favourable results—with a view to silencing rotary-wing aircraft, although no details of this work, or of the firms involved, may yet be published. It would seem, however, that any silencing that can be achieved must refer to the engine and transmission, and Mr. Sandys did, in fact, specifically speak of silencing "helicopter engines," without mentioning rotor noise. f Readers desirous of following the subject further are recom mended to our issue of June 12th last year, in which was published a full summary of a most informative symposium on aeronautical acoustics (from all aspects) held joindy by the Royal Aeronautical Society and the acoustics group of the Physical Society. Parti cularly appropriate, in view of the Minister's statement, was the paper by Mr. F. B. Greatrex of Rolls-Royce, in which was discussed most of the work carried out on jet-nozzle noise up to I that time (Rolls-Royce would clearly seem to be the "leading firm of engine-makers" referred to in Mr. Sandys' statement). This company are by no means able to give full details of the most interesting work which they are doing in this sphere, but it can be said that they are dividing the work into three main branches: the damaging effect of jet blast on local portions of t, aircraft structure, the effect of jet noise on people in the immediate ; vicinity of aircraft, and the character of air-to-ground noise as jet aircraft pass low overhead; principal attention is being paid to the first two problems. Further, it can be said that the company ; has various farms of sound-reducing jet nozzle in a fully developed : state; and throughout the development of these nozzles, strict ; limits have been, placed on the acceptable effect upon thrust and specific fuel consumption, and the company are able to state that their nozzles can already reduce the noise from a given turbojet ; by from six to eight decibels, without any performance penalty. Regarding the by-pass type of engine—of which the Conway is : the only example known to be running—Rolls-Royce have found that, largely owing to the lower mean jet velocity, it runs approxi- , mately eight decibels qiiie.ter than does a modern axial turbojet i of equal thrust. v. No details may yet be given of the mobile sound-reducing , devices referred to by the Minister, but it is likely that their i development is in the hands of the two principal companies : engaged in aero-engine acoustic engineering: Detuners, Ltd., of London, N.19, and Cementation (Muffel^e), Ltd., of London, r S.W.I. Both these firms are well known forttheir silencing equip ment for engine test beds, and full descriptions of these installa tions were published in our issues of September 5th, 1952, and December 12th, 1952, respectively. FORTHCOMING EVENTS July 8-12. British Institution of Radio Engineers: Industrial Electronics Convention, Oxford University. July 9. College of Aeronautics: Annual presentation day and ball, Cranfield. July 10. R.N.A.S. Brawdy: Air Day July 10. R.N.A.S. Lossiemouth: Air Day. July 10-11. International Radio Controlled Models Society: Annual contests, Birmingham. July 10-12. R.Ae.C. members' La Baulle rally. July 17-24. International Gliding Exhibition, London. July 18-25. Aero Club of Italy: International air week. July 20- Aug. A. B.G.A.: World Gliding Championships, Gt. Hucklow, Derby shire. July 24-26. World Model Aircraft Championships and Wakefield Trophy, Washington, U.S.A. Aug. 9-11. Institute of the Aeronautical Sciences: Conference on turbine- powered air transport, Seattle, U.S.A. Sept. 7-12. S.B.A.C. Farnborough display and exhibition. Sept. 9-12. Royal Aero Club: International invitation air rally. White Waltham. AIRCRAFT NOISE SUPPRESSION
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