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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 kinetic heating associated with supersonic flight produces temperature gradients within the aircraft structure. These in their turn are responsible for so‐called ‘thermal stresses’ in the components. The calculation of these effects falls into two stages. The first stage consists in the application of the theory of heat transfer to obtain the history of the temperature distribution in the structure. The second stage uses this data to obtain distributions of stress within the structure, resulting from these imposed temperature gradients and proceeds to assess their influence on strength and stiffness. The present paper is concerned entirely with this second stage of the problem and derives basic formulae for the analysis of beam‐like structures and components. The results can be applied to wings, fuselages, etc., on the one hand, and to linear reinforcing members like stringers and longerons on the other, in the same way as the usual theories of bending and torsion are applied in the isothermal case.

THE notation is that used by Love, The Mathematical Theory of Elasticity.

A monthly feature giving news of recent Government and professional appointments, industrial developments and business changes, etc. Three changes among the executives of Armstrong Siddeley Motors Limited of Coventry, Warwickshire, are announced by the Hawker Siddeley Group of 18 St. James's Square, S.W.I.

THE ‘Theory of Limit Design’ is a theory whose philosophy and methods will be familiar to most aeronautical engineers. The term ‘Limit Design’ may not be familiar and so it is probably necessary, before making com‐ments upon the theory, to give a short résumé.

AIRCRAFT wings, tail planes, fuselages and control surfaces have to satisfy certain mandatory requirements of stiffness. These requirements arc designed to ensure the absence of aero‐elastic troubles. They all take the form of a minimum specified limit to a stiffness, calculated or measured under the application of a definite force and constraint system. A ‘stiffness’ may be defined as the ratio of a force to its ‘corresponding’ displacement (see 5.2) and so the calculation of stiffnesses reduces itself to a ‘deflection problem’(1.1 (2)).

IT is paradoxical that we are endeavouring to supplant hydraulic power by other, alternative, media at a time when it is being successfully applied to purposes for which it is admirably, if not perhaps exclusively, suited.

CONSIDER a fuselage or wing structure in the form of a reinforced cylindrical tube. We shall base our analysis of the equilibrium conditions of this structure upon the assumptions outlined in 2.6. In particular referring in the first place to a skin panel lying between adjacent stringers and rings, we remark that this panel carries only shear stresses and is free from external forces. It follows, as we have observed before, that this panel must therefore be in a state of uniform shearing and so must apply uniform shear flows at its lines of juncture with the adjacent panels and the reinforcing stringers and rings. The equilibrium conditions to be satisfied at a stringer‐skin joint are now clear. The panels adjacent to the stringer apply different, but uniform, shear flows, to the line of attachment. The reaction from the stringer is determined by the rate of variation of its end load, for this clearly gives the rate of load input into the stringer. Adopting a consistent sign convention for the shear flows in the several skin panels we can thus enunciate the following theorem:

The paper describes an approximate method for the direct stress analysis of anisotropic swept cantilever plates, without the usual need for intermediate deflection calculations. The method of analysis employs the Principle of Least Work, in conjunction with the assumption that the load and stress components may be represented with sufficient accuracy by a power series in the chordwise co‐ordinate, the coefficients of this series being functions of the spanwise position only. The validity is thus limited to these loadings for which the series involved are convergent. A system of oblique co‐ordinates is used to simplify the analysis. Particular attention is focused on the parallelogram cantilever plate, subjected to a uniform normal loading and to a system of tip bending moments, twisting moments and shear forces. Theoretical predictions are compared with the results of an experimental investigation.

THE types of problems treated in the Theory of Structures can be conveniently classified under three headings: