A study of the laminar boundary layer on a yawed infinite wing in a compressible fluid is made. A method is presented for the investigation of compressibility effects by direct solution of the linearised equations of motion, first considerably simplified by the extension of a transformation due to Illingworth and Stewartson, which assumes a heat-insulated surface and a fluid of unit Prandtl number and a coefficient of viscosity which is proportional to the absolute temperature. As an example of this procedure the boundary layer near a stagnation point is calculated. The simplifications necessary for an extension of the momentum method, which is available for a yawed infinite wing in an incompressible fluid, are discussed, and this method is recommended for a first evaluation of the effect of compressibility.

The natural frequency of vibration of curved rectangular plates, with both simply-supported and fixed edges, is evaluated for the fundamental extensional mode. This mode is thought to be applicable when the plates are excited by a uniformly distributed pressure as may occur with a dynamic pressure wave. The natural frequencies corresponding to this mode increase fairly rapidly with the curvature of the plate.

The natural frequency of vibration of the plates when the mode is the fundamental inextensional mode is also considered. The frequency of this mode is higher than that of the extensional mode for small curvatures, but the inextensional mode frequency falls slowly with increase in curvature of the plate. Thus, if the curvature of the plate is sufficiently large, the frequency of the fundamental inextensional mode is lower than that of the extensional mode.

To calculate tail loads in flight it is necessary to know the angle of downwash at all points of the tailplane for any given value of wing incidence. Current trends in aircraft design place the tailplane off the plane of the wing. There exist solutions for the downwash in the z=0 plane for a delta wing with subsonic leading edges. This note gives a form of integral suitable for numerical evaluation which determines the downwash in the plane of symmetry (y=0) of a delta wing with subsonic leading edges. This note also points out an apparent error in Ref. 4 by G. N. Ward and gives a closed form for the downwash at a point whose forward Mach cone totally includes an arrowhead wing with supersonic trailing edges and whose centre line coincides with the axis of the cone.

A method is developed for designing thin finite wings with prescribed lift distributions. Particular attention is given to wings which, at a certain optimum angle of incidence, have zero loading along the whole leading edge. It is suggested that such a wing will have a greater range of lift coefficient for low drag than other wings with the same plan form.

On the basis of the linearised theory a formula, relating the wing surface to the pressure distribution over the surface, is deduced which differs from the usual potential relationship by avoiding the difficulty of the non-uniform convergence with respect to the normal distance away from the wing surface singularities. The surface integral which is developed includes a regular singularity and a definite limiting process.