Stratford's analysis of the laminar boundary layer near separation uses two physical ideas. In the outer part of the boundary layer, where viscous effects are small, the development is given by the condition that the total head is constant along streamlines, apart from a second-order correction for viscosity. Near the wall, however, viscous forces must balance the pressure forces, and the profile adjusts itself accordingly. Quantitatively these ideas yield a simple formula for predicting separation, which has been found to be particularly accurate.

In this paper it is indicated how the same approach may be used to yield the full distribution of skin friction along the wall. Further, the effects of suction may be incorporated into the method. Physically, suction affects the outer part of the boundary layer in that the streamlines are drawn towards the wall when suction is applied. At the wall, the balance between viscous and pressure forces is influenced by the momentum of the fluid which is sucked away. When these effects are accounted for quantitatively, the resulting formula for the skin friction is still very simple.

Several examples are considered, and comparison is made with exact theory and with approximate results by other methods. It is indicated that the method has a useful range of validity.

A theory of incompressible flow with axial symmetry through the impeller of a centrifugal compressor is given more fully and more accurately that by previous writers. The theory is applied to compute the flow through two different impellers. For each design the experimental axial velocity distribution at the impeller eye is in good agreement with that computed numerically from the theory. This means that for the impeller assembly—not untypical of modern designs—considered here, theoretical calculation of intake axial velocity should provide a useful guide to designers.

The fundamental frequencies of flexural vibration are determined for uniform isotropic rectangular plates that have free edges and pinpoint supports at the four corners. For the particular case of a square plate the lowest five frequencies and mode shapes have been determined. The second frequency is most unusual, since an infinite number of mode shapes exist with identical frequencies. Finite difference expressions, which simplify the treatment of the free boundaries for definite values of Poisson's ratio, are used in conjunction with extrapolation procedures to obtain the approximate solutions.

The pressure distribution on the wing of a centrally mounted wingbody combination due to anti-symmetrical body shaping (with respect to the wing plane) can be calculated in the case where the wing leading edge is supersonic by using the fact that the upper and lower halves of the flow field are independent and that each half can be treated by quasi-cylinder theory. When the leading edge is subsonic the anti-symmetric body shaping produces flow round the leading edge. This paper is concerned with wing pressure distributions including the effect of this flow round the leading edge.

Analytical solutions for the deflections and bending moments are derived for elastic struts with linearly varying axial loading applied either (a) along the undeformed straight strut axis or (b) at the strut axis in the deflected position. The instability of struts with various end conditions is discussed and the stability criteria are given as a series of curves relating the maximum compressive axial load with the maximum distributed loading. Furthermore, explicit formulae for the deflections and bending moment distributions have been compiled for several typical cases of lateral loading combined with the axial loading of the type (a), which is of some practical importance in aircraft structures. A numerical example is included to show the practical application of the general analysis to a typical strut problem.

Simple relations among the coefficients appearing in the admittances of dynamical chains are obtained by considering the initial motions which follow the application of certain impulses.