Search results

IT is well known that the drag of an air‐cooled engine can be much reduced by the addition of a suitable form of cowling. The present tests were undertaken to investigate the cowling of an air‐cooled radial engine and in particular to develop a suitable “helmet” cowling for this type of engine. Certain other forms of cowling have also been tested. From the results obtained estimates have been made of the probable improvement in performance resulting from the various types of cowling. Most of the work has been carried out in the No. 17‐ft. tunnel at the Royal Aircraft Establishment; the tests were begun in January, 1929, and have occupied the tunnel at intervals throughout the year.

THE increase in aeroplane speed, brought about by improved aerodynamic design and higher engine powers, together with the design restriction on airscrew tip speed resulting from efficiency considerations, has reacted on the airscrew performance during take‐off, and has made the take‐off more difficult.

THE importance of achieving a low structural weight is illustrated by simple estimates of the large decreases in aircraft gross weight and size made possible by conscientious weight saving in structural design. A brief review is then made of the many variables in aircraft design which affect the weight of the structure. The review is made chiefly to emphasize the close interplay in project work between the structural and aerodynamic effects of changes of layout. Finally some remarks are made about comparative structural design efficiency. It is concluded that good weight prediction formulae are at present the best means by which the structural design efficiencies of different aircraft may be readily compared.

THE following note has been received from Boulton and Paul, Limited.

THE author believes that at the time of presenting this paper there does not exist in Great Britain a company who will produce steel or high melting point non‐ferrous alloy castings by the Lost Wax Process on a commercial basis to the trade.

THE usual methods for obtaining data on the hydrodynamic characteristics of flying boats during flight tests involve motion pictures of an instrument panel and records of oscillograph traces. The analysis of the photographic records is so time consuming that the results are not always available when needed, and in many cases more data are accumulated than is physically possible to analyse. In order to conserve manpower and to obtain directly usable data, new methods have been developed for making quantitative hydrodynamic flight tests. The test techniques were devised to relate, whenever possible, numerical values to sensations experienced by the pilot of a flying boat during take‐off and landing.

THE Accidents Investigation Sub‐Committee of the Aeronautical Research Committee has issued a detailed technical report on the accident to the Junkers F.13‐type aeroplane G‐AAZK which occurred at Meopham, Kent, on July 21, 1930. The report, which fills ninety‐two pages, gives a complete account of the researches and technical investigations that were made at the instigation of the Sub‐Committee, much of which is of great technical interest. It is impossible here to do more than give a brief summary of the circumstances of the accident and the inquiries which led to the rejection of a number of theories of the cause, leading to the final conclusion that it was due to a phenomenon called “Buffeting,” which is defined as “an irregular oscillation of the tail unit, in which the tail‐plane bends rapidly up and down and the elevators move in an erratic manner.” It is caused by the eddies given off by the wings at large angles of incidence and is, the Sub‐Committee state, quite distinct from flutter, which, in the case of machines of the Junkers F.13‐type would develop only at speeds above 250 m.p.h.

Under this heading are published regularly abstract of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics, and publications of other similar research bodies as issued.

I WISH to thank the President and the Royal Society of Italy for the honour they have conferred by inviting me to read this paper before the 5th Volta Congress as part of a discussion on high speeds in aviation. The contributions which General Crocco has made to this subject have been valuable and stimulating. In the present paper the general question of high airscrew tip speeds is considered and the results obtained from model airscrew tests are reviewed.

Water systems in civil aircraft, stimulated by passenger comfort needs, have grown to be a comprehensive and important part of aircraft engineering. In this article, following a review of the system types, the design features arc discussed in detail and emphasis has been placed on the functional and hygiene requirements, and on the need for simplicity and weight conservation. Attempts have been made to augment air‐borne water supplies by reclamation means, but these have not been too successful. Investigations should therefore continue into the ways and means of improving the utilization of existing ‘fixed’ capacity systems. Installation safety aspects are also discussed.