The requirements of aeronautical engineers have been one of the greatest stimulants of metallurgical research and development during the present generation. Materials for the piston engine and the airframe had shared about equally the attention of the research metallurgist from the early twenties to about 1945. Then the gas turbine appropriated the major effort in metallurgical research because it was clear that progress with this propulsive unit was inescapably dependent upon the production of metals and alloys capable of giving reliable service at ever increasing temperatures. Here it was a question of evolving new materials having characteristics for which no appreciable demand existed before the advent of the gas turbine. The past five years have seen the airframe come back into the picture metallurgically, because of the new concern with fatigue and because supersonic speeds are bringing with them service temperatures for the airframe higher than anything arising while speeds of flight were comfortably subsonic.

From a general consideration of the available data on the flutter of wings with localised masses certain deductions are made as to the possible types of flutter that can occur. On the basis of these deductions it is shown that there is an optimum choice of modes for use in flutter calculations for wings with localised masses. These modes are obtained with artificial constraints imposed on the wing at the localised mass section fixing the wing at this section in translation and/or pitch. It is deduced that for certain mass locations types of flutter are obtained that are insensitive to increase of localised mass, beyond a certain value, with flutter speeds considerably greater than that of the fixed root bare wing. It is also deduced that for the majority of aircraft configurations the maximum flutter speeds for these types of flutter will be realised when the localised mass is in the region of two-thirds semi-span from the root. A limited theoretical investigation is made for a rectangular unswept uniform wing with symmetric and antisymmetric body freedoms, to illustrate and confirm the conclusions derived from general considerations. At the same time the investigation shows that an ill placed localised mass can reduce the wing flutter speed to a very low value.

The title of the paper infers that, in general, aircraft design is not fundamentally suitable for production and, for various reasons, design for quick and easy production must be the result of compromise. In practice optimum design and easy production never seem to coincide exactly. Refinement of design for production covers many broad conceptions.

In its broadest sense it should be the uppermost consideration from the very beginning of the design of the prototypes. The primary object of designing any new aircraft, civil or military, is to be able to produce a series of the most efficient fully approved and tested production aircraft at the highest possible rate in the shortest possible time. The first part of the paper, therefore, deals with the design and production planning phases of a new aircraft when, by joint consultation with the production departments, the design is viewed from the production angle from the outset.

This paper considers the problem of a reinforced elliptical hole in a plate under the action of a principal stress system of the type found in cylindrical and ellipsoidal pressure vessels. That is, stress systems in which the ratio of the principal stresses is not greater than two to one. It is shown that when the ratio of the major and minor axes of the ellipse can be chosen arbitrarily, practical reinforcements can be designed to give a maximum stress around the hole which is only slightly greater than the maximum stress in a similarly loaded plate with no hole. General expressions are obtained for the stress distribution in the plate around the hole, for the stress acting on a normal cross section of the reinforcement, and for the cross-sectional area of a reinforcement which gives a small stress concentration. These are used to find the variation in the stress distribution around the hole due to reinforcements having different cross-sectional areas when the applied principal stresses are in the ratio of two to one and Poisson's ratio for the material of the plate and reinforcement has practical values.

The Cantilever-Type mechanism often used in large missile erectors is subjected to heavy stresses when raising a missile from the horizontal to the vertical position for launching. In the event it becomes necessary to return the missile to the horizontal position, severe stresses in the erector, and possibly the missile itself may be developed if the lowering mechanism causes the erector to stop suddenly just before it reaches the horizontal position. This note presents a simple matric formulation of the problem which enables one who has access to an electronic digital computer to compute maximum deflections and load factors that occur as a result of a sudden stop.

This note describes an investigation into the secant and tangent moduli for flat panels in shear. Consideration is given to a comparatively recent analysis giving the secant modulus and comparison is made with he Society's Data Sheets.

A Set of normalised orthogonal polynomial functions suitable for problems concerning doubly built-in uniform beams was given in R. & M. 228l. The nth function of the set was expressed linearly in terms of three Legendre polynomials as follows:—

where