AIRCRAF T ENGINEERIN G 339 signifies that the material is subject to ageing; while the letter "R " denotes that the strength of heat-treated material is further increased by cold rolling. We write subject to correction, but we do not think there is any similar complete, and yet simple, method in use in connexion with British B.S. or D.T.D. specifications. The system appears to us to be logical and admirably informative. Certain "S"—meaning " wrought "—materials may be used, for instance, in either the "O" , " W " or " T " states. New Methods A stud y of the properties of these materials has shown that where THE SHEET METAL PROCESS as in the early days it was considered necessary to form them before heat-treatment, in the annealed state, the new methods introduced UST over a year ago (in th e October and November 1942 issues are making it increasingly possible to form the part s directly with of AIRCRAFT ENGINEERING) we published an Institute of the the material in the "T" , quenched, condition; thus eliminating Aeronautical Sciences paper by MR. F. R. SHANLEY of the trouble that used to arise from the distortion that occurred during Lockheed Aircraft Corporation on " Elastic Theory in Sheet- the heat-treatment. Forming Problems". • I n this issue we follow this by a Society of It is a far cry from the old " metal bashing " days and the authors Automotive Engineers paper by MESSRS. SCHROEDER AND HAZLETT, describe a number of modern methods of forming the material— also of the Lockheed Company, on " Sheet Metal Forming and bending, stretching, shrinking and drawing—with informative Assembling". The one paper therefore forms the complement of details of the tools and equipment used in them. the other and th e two together provide as nearly as possible a com plete guide to the latest practice in the design, tooling and utiliza tion of this process—or rather these processes, for there are a number of methods in operation. POST-GRADUATE EDUCATION Several readers have written to point out to us tha t we were wrong A Recent Process last month in stating that there is no aeronautical course in Scot One of the most striking features of the large-scale production of land. We very much regret that we had overlooked the course the modern stressed-skin metal aeroplane is the revolution it has which has been in operation at Glasgow University since 1935. brought about in the methods of producing innumerable parts in This brings the university courses in aeronautics to four; others sheet metal, some involving the formation of highly complicated being available at London, Cambridge and Hull, apart from the curved components. A new technique has grown up in the short post-graduate courses at Imperial College. space of three or four years; on which little has been published. Consequently, most firms in the industry have had to develop their The Fedden Committee methods by a process of trial and error with little knowledge of the There has been one development in the past month which experience of others to guide them. At one time, indeed, we were may be fraught with important consequences for the future. On constantly receiving requests for information to which we were 1 December, the MINISTER OF AIRCRAFT PRODUCTION announced, in unable to give helpful replies, We feel now tha t these two papers reply to a question in the House of Commons, tha t he ha d appointed together should give both the theoretician and the practical man all an Interdepartmental Committee, under the chairmanship of the guidance they can reasonably hope to expect. SI R ROY FEDDE N : " To prepare and submit to the Minister of Aircraft Production Formability of Materials detailed proposals for the establishment of a school of aeronautical The first desideratum is to recognize the properties of the various science within the general framework of the recommendations of materials so as to have a clear idea of their formability. Generally the Aeronautical Research Committee in their report of 10th August to the. Minister." speaking, as is now generally known though it was b y no means fully appreciated at first, the stronger the material the lower is its The A.R.C. report referred to has not been issued though it was suitability for the forming process. Similarly, for parts that are known that the Committee had been asked to advise upon the liable to distort during heat-treatment it is obviously desirable if training of students, of post-graduate standard, for the higher possible to use a material which does not require to be heat-treated. posts in research and industry and in the services. To go further back, there are usually one or more ways of designing a part for a given function, some of which lend themselves more Sir Melvill Jones's Proposal readily to forming than others. Though he specifically stated that what he was saying repre MESSRS. SCHROEDER AND HAZLETT give the answers to these sented his own views and must not be taken as anticipating the and a host of other questions which have been obtained from report, the remarks of SIR MELVILL JONES in the course of the hundreds of investigations and practical experiments that have been Royal Aeronautical Society's discussion can probably be taken as made by them and their staff. an indication of the lines of thought that are being followed. He advocated the establishment of a central school to supplement the U.S. Identification System post-graduate teaching at the universities. A comprehensive course should be given at the school, leaving the specialized The fact that the materials that are classified according to their research, and teaching through specialized research, to continue at "formability" are, naturally, those produced to American specifica the universities on present lines. He felt that the central school tions does not, we think, seriously detract from the value and interest should be situated on an aerodrome and near a big research of the paper to English readers, because the properties of these are institution. now widely familiar over here and, in any case, it gives the com position and explains the system of lettering which denotes the There is not, we think, much doubt that, in spite of the disclaimer, condition in which the material is available. The aluminium this proposal will prove to be roughly the basis of the Aeronautical alloys listed are divided into those which are " heat-treatable "— Research Committee's report, and it will be interesting to see how i.e. can be appreciably strengthened by heat-treating and quenching it is interpreted and developed by the ad hoc Committee appointed. in some prescribed manner—and those which are " strain-hardening" The only existing site would appear to be Farnborough, but i t may —i.e. can only be strengthened by cold working. The letter " 0 " be that an entirely new combined research establishment, experi after a specification number signifies that it is in th e annealed state ; mental aerodrome and post-graduate aeronautical school will be the letter "T " signifies the heat-treated state ; the letter " \V " proposed—though the cost would, of course, be enormous.
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Dec 1, 1943