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Sandwich construction with aluminium honeycomb cores bonded to faces with the adhesive films Redux 775, 775R and Bloomingdale FM‐47 is discussed. Drawings showing its applications to a series of components for various hypothetical aircraft arc included. Sandwich materials for supersonic aircraft of the types now entering production are reviewed, as well as the application techniques of the new Redux films. Some rules gathered from experience for the design of components with honeycomb cores, and solutions of special design problems with hypothetical wing panels, are treated. The paper then deals fairly fully with results from a programme of FFA investigations on this type of structure. The specimens discussed were bonded with Redux 775 and FM‐47 and consisted partly of tensile tests on cores, compressive tests on sandwich columns and shear tests on various sandwich webs. Design curves have been plotted in some cases. Further results are presented showing the influence of temperature on the shear strength of an aluminium alloy core and Redux 775 and FM‐47 films. Also a few creep results are given where the object of the tests has been to determine the optimum curing temperature and time for applying Redux 775 to yield minimum creep values. The room‐temperature results illustrate the excellent properties of honeycomb structures and the elevated‐temperature results indicate that bonded uninsulated aluminium sandwiches can be retained, even when the temperature due to kinetic heating approaches 70 deg. C. Finally, some remarks regarding future developments are made on various new ‘temperature‐resistant’ adhesives and on combinations of various materials for sandwich panels with external insulation, suitable for certain types of the next breed of supersonic aircraft.

A two‐spar cantilever box beam with forty‐five degrees sweep and oblique ribs placed parallel to the root clamping section was the subject of a series of static tests. Stress and strain distributions were determined, primarily in a region distant from the root and tip disturbances, to permit a stringent comparison with three well‐known swept wing theories and the simple theory of bending. Torsional and flexural stiffnesses were also measured and compared with these theories. The sequence of calculation for each method is presented and it is found that two of the theories provide accurate predictions of the stresses, strains and stiffnesses. The influence of rivet slip and rivet flexibility on the stiffnesses of the box is mentioned. As a secondary aim of the investigation, the distribution of normal and shear strain has been measured in the cover skin and spar webs at the root connexion. The design of swept box examined has been the subject of research in a number of establishments and a review of this other work is included.

THE efficient design and construction of the latest types of Swedish military aircraft, with wings with high critical Mach numbers, has necessitated a thorough investigation into the structural behaviour of swept and delta wings of both the thin and thick types. It is the main purpose of this paper to present some important test results and pertinent details of some of the small scale models which have been built to supplement the theoretical estimation of the stress distribution and deflexion patterns. In some cases these models have also been constructed to provide information on certain unusual structural configurations, which would have otherwise taken many months to obtain by using approximate theoretical methods. The stress distributions for each model are illustrated in such a way that comparison between the different types of structures may readily be made.

EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the Display is now held each year at the airfield of the Royal Aircraft Establishment, one of the world's most prominent aeronautical research centres. This interest becomes increasingly keen too, as the preview day comes closer, because new prototypes of unorthodox designs often appear a short time before the Show to illustrate the results of years of careful planning, development and research of the particular company. These designs often mould the path of progress for smaller countries without the economic resources to forge the way ahead alone. Most British citizens are very proud of their country's place in aviation today, both in the military and civil fields. This is understood by most foreigners because it is clear that Britain has won a place in aeronautical development second to none.

THIS month we publish an article by Mr B. R. Noton based on a thesis describing an investigation he made while a student at the College of Aeronautics at Cranfield.

IT is four years since we published a review of the S.B.A.C. Display. The omission has been due to several causes, among which may be mentioned our feeling that the event was fully covered at the time by our weekly contemporaries whereas our account could not perforce appear till a month later, by which time it might be felt to have become a matter of history rather than topicality.

FATIGUE of aircraft structures has recently become an important subject, particularly during the last two years, and many research organizations and aircraft manufacturers are now engaged in investigations into the problems of fatigue. Three international events dealing comprehensively with most aspects of fatigue have been arranged, and the first of these, organized by a Swedish committee of the International Union of Theoretical and Applied Mechanics, took place last May at the Kungliga Tekniska Hogskolan in Stockholm. The second conference, specifically concerned with fatigue of aircraft structures, will be held from January 30 to February 1, 1956, at Columbia University, New York. (Information may be obtained from Professor A. M. Freudenthal, 716 Engineering, Columbia University, New York 27, N.Y.) The entire field of metal fatigue will be covered by the third conference, organized by the Institute of Mechanical Engineers, to take place in London from September 10 to 14, 1956.

The notation and equation numbers in the text are those of Hemp's report.

A review of CFRP dealing with its processing, properties and some of the ways in which it could be used in conjunction with conventional materials. The importance of the utilization of carbon fibres in commercially useful as well as experimental structures is discussed. This may be achieved by using the fibres in conjunction with conventional sheet metal components, as a preliminary step toward the 100 per cent reinforced plastic structure. A few such applications are described, together with a brief summary of the fibre processing and properties as an aid to preliminary design studies.

Simple expressions for upper and lower limits to the shear modulus of honeycomb sandwich cores are obtained by application of the Unit Displacement and Unit Load methods in conjunction with simplifying assumptions as to the strain and stress systems respectively in the core. The theory is given for cores built up from foil ribbons to form cells of general honeycomb form. Test methods for the experimental determination of the shear modulus are also discussed. Of these, the three‐point bending test on sandwich beams is considered most satisfactory and results of such tests on steel and aluminium foil honeycombs show good agreement with the theory.