AS might be expected, the problem of aircraft noise receives lengthy and detailed consideration in the Final Report of the Wilson Committee on the Problem of Noise. The subject of…
Abstract
AS might be expected, the problem of aircraft noise receives lengthy and detailed consideration in the Final Report of the Wilson Committee on the Problem of Noise. The subject of noise was found by the Committee to be so vast that it was necessary to form three sub‐committees to examine specific areas, and one of these—under the chairmanship of Mr F. B. Greatrex [Chief Engineer (Staff Engineering) Rolls‐Royce Ltd.]—devoted its attention to noise from aircraft.
DURING the 1950s noise around airports increased steadily with increasing traffic and size of aircraft. With the introduction of heavy jet transports the very different quality of…
Abstract
DURING the 1950s noise around airports increased steadily with increasing traffic and size of aircraft. With the introduction of heavy jet transports the very different quality of noise (compared to piston engines) highlighted the problem and the upward trend had to be halted. This led to a considerable increase in effort to investigate the noise of turbojet engines.
The author was asked to prepare this paper for a discussion on take‐off and landing noise problems on the supersonic transport at a Symposium at Southampton University. He was in…
Abstract
The author was asked to prepare this paper for a discussion on take‐off and landing noise problems on the supersonic transport at a Symposium at Southampton University. He was in the fortunate position of being sufficiently detached from direct participation in the project that he did not need to be hampered too much by hard facts—he could hope to keep the interest of his audience by raising general problems and discussing methods of solution without specifying what the actual solutions were going to be. After all there is nothing more inhibiting to a good lunch‐table conversation than the presence of someone who actually knows the answers to the problems under discussion.
DISCUSSIONS on aircraft noise problems unfortunately result too often in inconclusive statements of good intentions on the one hand from those who are connected with making the…
Abstract
DISCUSSIONS on aircraft noise problems unfortunately result too often in inconclusive statements of good intentions on the one hand from those who are connected with making the noise, or emotional recrimination on the other from those who have to suffer it. Administrators and even eminent aircraft designers protest ignorance of acoustic technology, while sufferers from noise show a marked reluctance to face the most elementary economic facts. Perhaps one of the reasons why many people are still suspicious of technology in this country is that we have not yet mastered the art of presenting all the factors, and particularly the economic factors, in a technological problem in such a way as to make it possible to see clearly the issues involved. This paper is an attempt to give a better understanding of the interactions between the technical, economic and political sides of the aircraft noise problem. It is meant to show how these interactions might be studied, rather than to give definite answers to specific problems.
IT does not require a very large crystal ball to envisage the growth of aviation during the next fifteen years. Sea travel has become too slow; air travel has become reliable and…
Abstract
IT does not require a very large crystal ball to envisage the growth of aviation during the next fifteen years. Sea travel has become too slow; air travel has become reliable and more independent of weather conditions; world trade has forced travel into the remotest areas; industrial countries have become more affluent, and the urge for private world travel has accompanied affluence. It is not surprising, therefore, to hear the Chairman of the British Airport Authority, Peter Masefield, predict a fifteenfold growth in air traffic in the United Kingdom during the next twenty years and to find the F.A.A. confidently anticipating a doubling of passenger traffic in five years and a nine‐fold increase in small jets in the same period.
Originally, this article took the form of the Twenty‐first Brancker Memorial Lecture delivered to a meeting of The Institute of Transport. The author began his lecture by saying…
Abstract
Originally, this article took the form of the Twenty‐first Brancker Memorial Lecture delivered to a meeting of The Institute of Transport. The author began his lecture by saying how honoured he was by the invitation to present the 1964 Brancker Memorial Lecture and that he felt especially privileged to have the opportunity of surveying a prospect which he believed would have excited Sir Sefton Brancker's most ardent enthusiasm—the prospect of reducing inter‐continental journey times‐by air to the same durations as those universally accepted for inter‐city journeys by rail and road. Previous Brancker Memorial Lectures had summarized the general development of British civil aviation from its earliest days to 1946 and had covered particular aspects of its very rapid expansion since that date. 1946 was a significant year because it marked the resurgence of commercial flying after seven years of wartime restrictions and regulation; it promised a new deal to both operators and travelling public, with the opportunity of usefully applying technical advances achieved during the war period; at the same time it threw into sharp contrast the relative design capabilities of the British and American aircraft manufacturing industries.
MANY papers have been written in recent years on various technical aspects of the supersonic transportaircraft—aerodynamics, propulsion, structures and systems. In attempting to…
Abstract
MANY papers have been written in recent years on various technical aspects of the supersonic transportaircraft—aerodynamics, propulsion, structures and systems. In attempting to give yet another paper on this topic, it was felt the subject should be reviewed in a more general way, by considering a variety of engineering problems which arise in the design and development of such an aircraft.
THE thirty‐eighth annual Exhibition of the Physical Society was held at the Imperial College, South Kensington, on April 8–13, and the account which follows describes a few of the…
Abstract
THE thirty‐eighth annual Exhibition of the Physical Society was held at the Imperial College, South Kensington, on April 8–13, and the account which follows describes a few of the items shown, which have been selected because of their more direct interest for the aeronautical engineering profession.
This paper covers British European Airways' experience with the operation of turboprop aircraft and concludes with some thoughts on their future possibilities.
The bulk of jet engine noise developed at high powers arises from the turbulent mixing of the jet efflux in the surrounding air, as judged from model experiments, and has a…
Abstract
The bulk of jet engine noise developed at high powers arises from the turbulent mixing of the jet efflux in the surrounding air, as judged from model experiments, and has a continuous spectrum with a single flat maximum. The high frequency sound arises from fairly close to the orifice, and reaches its maximum intensity at fairly large acute angles to the jet direction. Lower frequency noise arises from lower down stream and its maxima make smaller acute angles with the jet axis. The possible origins are briefly discussed in view of Lighthill's theory and refraction effects. The most intensesound has a wave‐length of the order of three or four exit diameters, and originates between five and ten diameters from the orifice. A semi‐empirical rule of noise energy depending on the jet velocity to the eighth power and the jet diameter squared gives a rough estimate of the noise level for both cold and heated jets. Further noise from heated or supersonic jets may occur through eddies travelling at supersonic speed and so producing small Shockwaves. Model experiments have shown that interaction between shock‐wave configurations in choked jets and passing eddy trains generates sound and this initiates further eddies at the orifice. The directional properties of this sound are quite distinctive, the maximum being in the upstream direction. Methods of reducing jet noise are briefly discussed.