Since the introduction of aluminium-zinc-magnesium-copper alloys, investigations into the behaviour of these high strength materials, over a wide range of composition, have indicated the significance of corrosion as a factor affecting the cracking of these alloys after prolonged stressing at loads below the ultimate tensile strength of the material.

Most of the previous work designed to assess the stress-corrosion resistance of aluminium-zinc-magnesium-copper alloys (D.T.D. 683A*) was carried out on sheet and plate material and the present investigation is concerned with the examination of these materials in the form of large hand-forged slabs, tested in the short transverse direction.

The main advantage of the method presented in Part I of this paper is the generality with regard to the shape of the wing plan form. This is a welcome innovation in the field of supersonic wing theory, where methods of solution of the usual lifting problem are restricted to a limited number of wing shapes. Most of the lifting characteristics of wings are now known at supersonic speeds, but the range of wings with curved subsonic leading and trailing edges needs further investigations. Therefore it seems that the extension of the design problem to include these lifting problems is a useful addition to the extensive literature on the subject.

The “frozen stress” techniques of photoelasticity can give a complete knowledge of the stress, system in a solid body, but the examination of the stresses requires more time and care than in corresponding flat plate tests. In tests on tubes with transverse circular holes, sponsored by The Royal Aeronautical Society, all practicable geometrical shapes are examined and the maximum stress is measured in tension, bending and torsion. The results are comprehensive and show the inadequacy of previous results. In all cases the maximum stress occurs inside the bore of the hole. The accuracy of all the graphs of stress concentration factors is better than five per cent.

The paper concerns a phenomenon which occurs in rows of closely spaced blades, as in an axial flow compressor, when the flow around the blades approaches the stalling condition. Patches of stalled flow can propagate along the blade row, thus causing cyclic variations in the lift on individual blades. Under certain conditions this cyclic loading can lead to large blade stresses, and ultimately to blade failure.

This report describes the design of an annular entry for the axisymmetric flow into a circular duct, shaped so that the wall velocity gradients are favourable to the development of the boundary layer flow. As a first step the accelerating flow around a two-dimensional 90° duct bend with favourable gradients was obtained. This shape was modified and the axisymmetric flow pattern through it obtained by a combination of electrical analogue and relaxation methods and then checked by experiment. The favourable gradients were retained in the axisymmetric flow.

An analytical solution, using complex variable methods, is given for the problem of the stress distribution due to an elliptical hole, reinforced around its boundary, in a plane sheet subjected at infinity either to an arbitrary constant stress system or to a bending type stress system. Numerical results were obtained for a wide range of parameters, including three different shapes of ellipse, and ten different amounts of reinforcement. Poisson's ratio was assumed to be 1/3.