In this paper lower bounds are obtained for the intensity of the sonic bang resulting from a slender aircraft flying straight and level at supersonic speeds. The lower bounds are obtained for an aircraft subject to various constraints on its total lift, volume, area distribution and centre-of-pressure position. The work described proves the results quoted in an earlier paper, corrects the results given in that paper for the general configuration, and extends the results to cover more constraints, mainly the centre-of-pressure position.

The various methods which axe available for controlling the rolling motions of a model suspended in an electro-magnet system are discussed. Data on the moment capability and damping achieved with some of the possible control techniques are presented, together with details of the roll control system adopted for the six-component magnetic balance which has been developed at Southampton University for an 8 in × 6 in supersonic wind tunnel.

The problem considered is the theoretical analysis and design of reinforcement around holes in plane sheets subjected to prescribed stresses at infinity. The reinforcement is taken to be an extensive thin plate attached to the sheet rather than the usual “compact bead” placed around the inside of the hole. The optimum design of the hole and the reinforcement is treated in two ways, firstly as an attempt to produce a “neutral hole” and secondly, to achieve the smallest stress concentration with the minimum amount of reinforcement. It is found in two cases that the plate-reinforcement can be as efficient as the bead but that, for both types, the validity of the theory is doubtful just when they are most efficient.

A method of calculation has been developed in which all terms in the momentum integral equations in the streamwise and cross-flow directions are taken into account so that no restriction to small cross-flows is imposed. The essential feature of the method is the use of an entrainment equation which enables the development of the streamwise form parameter to be calculated along with the streamwise and cross-flow momentum thicknesses. Mager’s quadratic expression is used to relate streamwise and cross-flow profiles. The method has been applied to the idealised case of an infinite swept wing with free-stream velocity over the forward part of the chord and a linear adverse velocity gradient over the rear. The position of separation, the directions of the surface streamlines and the development of streamwise and cross-flow profiles have been calculated for a series of angles of sweep and for adverse pressure gradients of varying severity.

This paper investigates the effect of the torsional stiffness of the ribs on the buckling strength of stiffened plates compressed in the direction of the ribs. For the case of plates simply-supported on all sides, a closed form formula is derived for calculating the buckling load.