Recently the use of Maclaurin’s series was illustrated for the analysis of orthotropic plates. Formulae connecting the deflection of orthotropic plates to that of the corresponding isotropic plate are established here, thus eliminating the need for solving the characteristic equations of orthotropic plates. Rectangular plates with two opposite sides simply-supported and one of the other two sides elastically restrained against rotation are considered.

Five years have now elapsed since the last report on helicopter development in France was given by Francois Legrand, then Chief of the Rotary Wing Section at the “Service Téchnique de l'AéYonautique”. At that time, Sud-Aviation had been in existence for two years and the production of helicopters was at an early stage, with almost only French operators. In 1963, Mr. Legrand became Sud-Aviation helicopter chief designer; since 1959, the position of France in the helicopter production world has asserted itself considerably.

The development of the P.531 family of helicopters covering the period of approximately 5 years is presented. Evolution from the first basic aircraft towards a land-based general purpose helicopter, the Scout, and towards a shipborne helicopter operating from small ships, the Wasp, is presented. The basic design features of the Scout are described briefly as broadly representative of the family. Development experiences are reviewed under the following main headings:—

• (i) Ground resonance investigations.

• (ii) Development of satisfactory flight handling characteristics including engine/rotor control system

• (iii) Substantiation of structural integrity,

• (iv) Development of systems and operational equipments.

• (v) Environmental and climatic testing.

Development of miniaturised auto-stabilisation/autopilot system, for small helicopters, considered to be an important programme, is briefly reviewed. More detailed consideration is given to operations from small ships. The possible design solutions to ensure satisfactory operation from small ships are briefly reviewed, and the reasons for the solution chosen for the Wasp, i.e. four wheel undercarriage are given. Development experiences with the preferred solution are briefly described. It is shown that for operation from small ships in the Naval application a fair degree of complexity is unavoidable independent of the size of a helicopter.

Some statistical data on the development efforts expended are given and some tentative conclusions drawn, aiming at determination of the necessary conditions which would promote a relatively speedy development of a new helicopter.

The continuing increase in the standard of living has brought with it a marked trend towards the use of processed vegetables, especially those which are prepared and require little or no attention before serving. This has been particularly marked in frozen foods and more recently dried foods, including accelerated freeze dried products.

The customer demands products which are of a consistently high quality and the food industry is therefore concerned with the purchase of crops of a very high standard in order to produce consistent products for sale. This creates a demand for produce which is free from blemish, pest and disease effects. It also necessitates crops being harvested at the optimum time and any one crop should be as uniformly mature as is possible.

The existing hypersonic test facilities at the Royal Aircraft Establishment are described. In particular the Hypersonic Tunnel and the Shock Tunnel are considered in some detail from the aspects of design, performance and use, with a view to seeing what lessons can be learned from their construction and operation. The reasons which led to the building of the present facilities are compared with modern ideas for tackling hypersonic research. Consideration of the problems which will require experimental investigation in the future suggest that additional tunnels will be required which, like the Hypersonic Tunnel, will run steadily for periods of seconds rather than for much shorter times. The air supply and power requirements of such tunnels are given and the recent developments in heater design which make their realisation possible are reviewed.

The world of hearing is made up of two types of sound— on the one hand, that which provides communication, be it in the form of speech, music or the noise of a car or dog; on the other hand, a noise which interferes with that message, or a sound consisting of an unwanted message, intruding upon a person's thought processes or sleep. It is always difficult to separate these two functions, since one man's noise is another man's message, and this is particularly so for quiet noises heard at night or occurring sharply to frighten and alarm. It is for this reason that the law regarding noise has been less specific than in other fields and it is for this reason that seldom have any clearly defined limits been specified.

This brief paper attempts to outline the present methods for the legal control of aircraft noise and, by emphasising potential weaknesses, draws attention to possible improvements for the future. The views expressed are personal opinions only and must not be interpreted as the views of Insurers generally or the British Aviation Insurance Co. Ltd., in particular.

Professor Richards has clearly described the technical problems involved in the control of aircraft noise. In its essentials, any system of legal control must involve the evolution and enforcement of standards in the design and operation of aircraft, airports and aircraft-affected communities.

The paper concerns rocket engines of the type currently employed in ballistic missiles and satellite booster vehicles, outlining some advantages to be gained from a reduction in thrust towards the end of the burning period. Several methods of throttling a rocket engine are then examined.

Low frequency combustion instability which can arise when an engine is operated below its normal thrust level is considered in some detail, including the effect of such instability on engine performance. Means of ensuring stable operation both in the main thrust chamber and the turbine gas generator are described and compared.

The mechanism of heat transfer to the main injector has been studied and the modifications to the injection pattern necessary to maintain this at a safe level are described. Also, changes in the overall heat transfer rate to the thrust chamber walls are discussed with special reference to the formation of an insulating layer which occurs with carbon-bearing propellants.

The discrepancy between the inlet heads of the propellants at high vehicle accelerations is noted and the relative effect of this on engine operating conditions for the throttled and unthrottled cases described.

Finally, the effect of pressure change on the thrust chamber performance is considered with reference to studies made on the Rolls-Royce RZ.2 engine.

At the very high flight speeds of ballistic missiles, re-entering satellites and meteorites, the air in contact with the body may attain very high temperatures and may even become ionised. For example, the air in the stagnation region of a low-drag ballistic missile re-entering the Earth's atmosphere can reach a temperature of 8000°K and the electron density may be as high as 1016 per c.c. In any experimental work on high enthalpy flow it therefore becomes necessary to have techniques for measuring these high temperatures and high electron densities. The aim of the present paper is to describe techniques for measuring these quantities.

I do not think that any report was ever so fortunate in the timing of its publication—although this was quite accidental— as the Robbins Report. An expiring Government and an aspiring Opposition have both welcomed it with open arms; a quite unusual state of affairs. It has received also a very good press, although there have been criticisms by some who were expecting recommendations on special issues such as sandwich courses or the place of liberal studies in technological courses and so on. But anyone making criticism of this kind has clearly not read the terms of reference given to the Committee, which were to review the pattern of full time higher education and in the light of national needs and resources, to advise the Government on what principles its long-term development should take place and to consider whether there should be any changes in the pattern and whether any new types of institution were desirable. Detailed problems lying within the pattern were outside our terms of reference.

The United States Army is now engaged in the selection of a Light Observation Helicopter (commonly referred to as the LOH) from three competing designs. It is estimated that large quantities will be procured to fulfil an operational requirement during the 1966-1975 time period. The paper describes the overall programme by examining the basic requirement and the development concept. In addition, a description of the actual hardware being developed is given and some economic considerations of the modernisation of the observation fleet are discussed.

In some recent impact tests in which thin walled square tubes were loaded axially to produce large scale buckling of the walls, a difference occurred between the behaviour at high speeds and that at low speeds. The tubes, standing on an anvil, were struck by a falling steel tup which was guided to strike the tubes approximately axially. At the higher speeds damage was confined to the impact end of the tube, with a short wavelength buckle adjacent to the end and longer waves farther from the end. At lower speeds damage occurred at either end, or, jn many cases, in the central region of the tube. The wavelengths in these low speed tests were longer than those occurring at high speeds. These two types of behaviour are illustrated on Fig. 1.

The natural frequency of the fundamental mode of star-shaped membranes whose boundary is given by an equation in polar form is determined. The boundary conditions are satisfied identically by conformally transforming the complicated shape onto a unit circle. The transformed partial differential equation is solved by two different collocation techniques.

Tsetse flies are generally classed as insects of medical and veterinary importance, but qualify for consideration by this group by virtue of their indirect influence on agricultural development in Africa and their possible control by the application of insecticides from aircraft.

Tsetse flies are confined to the African continent and a few small off-shore islands. They are widely distributed between 14°N and 29°S wherever the environment is suitable; and are absent from N. Africa, the Sahara, the Red Sea Zone and the Somalias, and the highlands of Ethiopia, and from the Union of South Africa, except Zululand.

The purpose of this note is to report the results of an experimental investigation which was conducted to permit the local mass transfer rate around a sphere to be visualised. The present problem of mass transfer from a sphere had its origin in a study of the evaporation of a water droplet in a superheated steam atmosphere. Because of the small physical size of the droplet and the difficulty of measuring local mass transfer rates from the droplet surface, it was necessary to employ a large scale model to study local transfer rate around a sphere. It was considered that flow visualisation would afford at least a qualitative result of local mass transfer rate. In fluid mechanics studies, the flow visualisation techniques are well known. Such methods include the use of smoke filaments, tufts, or chemical coatings and so forth to provide information about the state of boundary layer over a solid surface, fluid particle paths and state of flow.

Any vehicle that is required to travel at high speed over the surface of the earth (either land or water) should have

• (a) Low drag and

• (b) Some form of spring suspension.

Anyone who doubts the need for the second of these, for travel over water, should consider the accelerations involved in following the surface of the sea at high speed and observe the behaviour of a high-speed motor boat on rough water.