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IN so far as it is possible under wartime restrictions, the purpose of this paper is to present a comprehensive picture of the more important problems in aircraft structural design and research in the interest of advancing the knowledge of those engaged in industries which formerly had but slight connexion with aeronautical engineering, but today are deeply involved in various phases of aircraft work. A similar objective was stated by Dr. A. G. Pugsley as follows:

FOR the fourth time we are enabled, through his courtesy, to bring to the notice of our readers a paper read in America by Mr. F. R. SHANLEY of the LOCKHEED AIRCRAFT CORPORATION. On this occasion it is to the AMERICAN SOCIETY OF MECHANICAL ENGINEERS that we are also indebted for permission to reproduce it in AIRCRAFT ENGINEERING. Owing to the incidence of the occasion on which it was presented, the present paper was written for the information of those engaged in general mechanical engineering on the problems peculiar to aeroplane structures, but it is equally interesting and valuable to the aeronautical engineer, who will undoubtedly find much food for reflection in it. We have previously called attention to the essentially practical qualities which the author brings to bear on the research matters that engage his attention and to his generosity, and that of his firm, in making these available to other workers. This is in accordance with an admirable American tradition. Would that it were equally prevalent in England; but unfortunately a less open‐hearted view of such publication has always been taken in this country than across the Atlantic and we have as yet noticed no signs of a changes of attitude.

THE main object of this paper is to help bridge the gap that exists between the scientific knowledge of materials and the practical application of that knowledge to the production technique of sheet‐metal forming. During the past year the Production Research Group of Lockheed's engineering department has given special attention to this important problem and has worked closely with the production departments in an effort to put sheet‐metal forming on a scientific basis. The following discussion is based largely on the work of the Production Research Group, as reported in various references and in papers yet to be published. Mr. William Schroeder and Mr. G. A. Brewer of this group have been particularly helpful to the author in the preparation and editing of the technical material. Because of the scope of the present paper, detailed discussion and analysis of new developments cannot be undertaken; however, such information will be made available as soon as possible in the form of individual papers by those directly responsible for the work.

IN our report of the tenth annual meeting of the Institute of the Aeronautical Sciences we shall not follow precisely the order in which the sessions occurred nor at all times classify the papers in exactly the manner of the meeting. Unfortunately, certain of the papers presented will not be found in our review owing to lack of preprints, but this in no way reflects on the value or timeliness of the papers omitted in the review.

MOST of the structural analysis problems that have resulted from the use of “thin‐walled” construction seem to fall into two general classes: Stress distribution and buckling. Even these classes cannot be entirely separated, as the stress distribution can be greatly affected by buckling phenomena. A thorough understanding of the general principles of buckling (or structural instability) is therefore essential for efficient and safe design of modern aircraft structures.

JUST over a year ago (in the October and November 1942 issues of AIRCRAFT ENGINEERING) we published an Institute of the Aeronautical Sciences paper by Mr. F. R. SHANLEY of the Lockheed Aircraft Corporation on “ Elastic Theory in Sheet‐Forming Problems”. In this issue we follow this by a Society of Automotive Engineers paper by MESSRS. SCHROEDER AND HAZLETT, also of the Lockheed Company, on “Sheet Metal Forming and Assembling”. The one paper therefore forms the complement of the other and the two together provide as nearly as possible a complete guide to the latest practice in the design, tooling and utilization of this process—or rather these processes, for there are a number of methods in operation.

AT Lockheed (Ref. 18) the double‐acting press has been used toad vantage in this work, as it permits the part to be held at the edges while the punchforms it, thereby building up the desired tensile stress. This is illustrated by Fig. 32. The same general effect may be obtained in the single‐acting press with rubber punch by the use of special concave blocks in which the sheet is clamped at the edges by means of beaded plates or other devices. Mechanical stretching machines are also available for this type of work. These methods are generally not as satisfactory as the double‐acting press, however, as the latter permits greater control over the edge restraint conditions.

THE paper by Thompson, Wadsworth and Louat on ‘The Origin of Fatigue Fracture in Copper’ contains much valuable information which, together with other recent work of the same nature, affords a basis for reviewing various theories concerning the mechanism of fatigue. In the light of recent information, it appears probable that the greatest road‐blocks in our progress toward understanding fatigue have been mental or semantic in nature. It is remarkable that a phenomenon of such importance has resisted solution for over 100 years, in spite of the tremendous amount of testing, papers and conferences that have been devoted to solving the problem.

For 5,000 years man has had experience of metal. Considerable though this period is, if judged on an historical rather than on a geological basis, it has proved all too short for the determination of the major chemical and physical characteristics of even that small group of metals used in engineering. This lack of knowledge is particularly conspicuous with regard to the property, now called ‘Fatigue’, whose very existence was not recognized in this country until 1849.

AIRCRAFT ENGINEERING was born in March 1929 of the belief that the emerging technology from which it took its title would become a fundamental element of engineering progress. The keystone of its policy was that it would attempt to meet the needs of engineers and students working in this field and that its contents should be ‘written by engineers — for engineers’. That this venture was fully justified has been amply vindicated by the achievements of the industry during the ensuing 41 years — as recorded in the first 500 issues of this Journal, the major milestone celebrated this month. This is a propitious occasion on which to review the record to date because, although aviation has always been about looking forward, history is instructive and it is the impressive performance of the aerospace industry to date that inspires and motivates confidence in its future.