The paper presents a solution of the non-linear problem of the deformation of slender rectangular plates which are stiffened along their edges by elastically compressible stiffeners flexible in the plane of the plate. The webplate is assumed to be simply-supported along its contour. Numerical results showing the effect of flexural and normal rigidity of stiffeners are given for a square webplate loaded by shear and compression.

The present work investigates feedback control of flutter using piezoceramic strain actuators. A two degree-of-freedom oscillating airfoil model with the air loads simulated assuming unsteady aerodynamics is considered. Various feedback measurement combinations for SISO feedback control and strain actuation in the heave and pitch direction are studied to quantify their effect on flutter. The effect of sensor placement on the airfoil, for combined pitch and heave measurement feedback, is also studied. The results show that for a given aeroelastic system, sensor location is an important parameter in realizing an increase in the flutter speed. It is demonstrated that the flutter speed can be increased by more than 50% through strain actuation in the pitch direction.

The loss of torsional or flexural stiffness due to thermal stresses in a thin solid wing is now well known and has been considered by a number of authors, e.g. Dryden and Duberg, Vosteen and Fuller, Bisplinghoff, Hoff, Budiansky and Mayers, Argyris, and the present author. Exact analyses are available only for the “one-dimensional” case of a wing of infinite aspect ratio with arbitrary chordwise distribution of wing thickness and temperature. The loss of stiffness in a similar wing of finite aspect ratio is not as great and, in particular, the proportional reduction in flexural stiffness in a low aspect ratio wing will tend to be less than the proportional reduction in torsional stiffness.

The problem of a two-dimensional pressure field moving over a free surface is analysed by dynamic modelling techniques. Using a simple second order linear differential equation, it is possible to obtain all the classical theory rersults for a uniform field in deep water. Squire’s results for the non-uniform pressure field of a planing wedge are also duplicated. Further results, not hitherto obtained with classical theory, may explain some anomalies associated with the classical theory. The method has the advantage that results for a large number of “pressure field distributions” have already been tabulated by workers studying the response of simple lumped parameter mechanical dynamic systems.

A conclusion of some practical importance in applied hydrodynamics is that the wave drag of a pressure field varies with its distribution. The more non-uniform a pressure field the greater its wave drag. The theory also gives insight into the occurrence of “humps and hollows” in model resistance curves, and gives some insight as to why a minor change in form may cause a major change in wave resistance.

‘Active Control Technology’ (ACT) is a jargon of the last few years describing the technological requirements which permit the earlier concept of the Control Configured Vehicle (CCV). The CCV idea was that by suitably driving specially arranged controls, various desirable aircraft characteristics, notaby stability and good handling, could be provided synthetically and as a result the tail and fin sizes could be reduced and the wing mounted in a more advantageous position on the fuselage: more freedom of choice was thus given the designer in settling his configuration. The technology to do this was barely ready at the time but meanwhile has been progressing apace in the form of minicomputers, electrical signalling, digital control systems and a deeper analysis of what is involved in a total system.

This work aims to describe a mathematical model and a numerical method to simulate a thin anisotropic membrane moving and deforming in 3D space under a dynamic load of an arbitrary time and space profile. The anisotropic continuum medium model described in the article can be used to model a membrane made of composite material using its effective elastic parameters. The model and the method allow the consideration of problems when the quasi-static approximation is not valid and elastic waves caused by the impact should be calculated. The model and the method can be used for numerical study of different processes in thin composite layers, such as shock load, ultrasound propagation, non-destructive testing procedures and vibrations. The thin membrane is considered as a 2D object in 3D space, an approach that allows a reduction in the computational time compared with full 3D models, while still having an arbitrary material rheology and load profile.

The subject of “Line-squalls” is one which has not been entirely neglected in the proceedings of this Society, but it has not hitherto been treated in any degree of detail. Sir Napier Shaw, in a lecture delivered on January 7th, 1914, on the subject of “Wind Gusts and the Structure of Aerial Disturbances,” briefly cited the line-squall as a phenomenon involving a violent commotion in the atmosphere, illustrating his remarks by sketches and meteorological records relating to a well-marked instance on October 14th, 1912, at Aberdeen.

The CHAIRMAN, in introducing the Author, said that Dr Morley had been for 16 years on the scientific staff of the Engine Department of the Royal Aircraft Establishment and, at the end of the war, was Deputy Head of the Gas Dynamics Division which subsequently became the Supersonics Division Three years after that he was senior lecturer of aircraft propulsion at Cranfield In his present position as Forward Projects Engineer for the Napier Company he was engaged on technical investigations into developments in aeronautics

The recent years have seen a tremendous increase in the importance of the helicopter both as a defence aircraft, for anti mine, anti submarine and assault purposes and as a civil transport between busy centres, and it has been overwhelmingly successful in a multitude of special duties from rescue work to crop spraying, some impossible with fixed wing aircraft The wider application of the helicopter in these many roles has directed increased attention towards the enhanced engine performance possible with the gas turbine, and to the more difficult problems of coupling the greater potential output of this form of engine with the inherent safety features of the aircraft

I was delighted and honoured to have been invited to give this lecture on the technical aspects of the Schneider Trophy and the world speed record attempts. Great Britain and Italy were the main contenders in the final and most exciting phase of the contest. As the Macchi aircraft were the most successful defenders of the Italian colours and, being myself the successor to Dr. Mario Castoldi, designer of the famous Macchi racers for the Schneider Trophy, I was very pleased to accept the kind invitation of the Society to give this lecture, especially in consideration of the fact that, as far as Macchi contribution is concerned, it was possible for me to collect first hand information directly from the people who actively collaborated with the racing effort.

A theoretical study is presented for the investigation of a potential-flow model for enhancing lift over a flat-plate aerofoil experiencing thin aerofoil stall. Rather than suppressing the leading-edge separation, flow is assumed to separate tangentially at the leading edge and made to reattach smoothly at the tip of a forward-facing fence joining the plate tangentially on its upper surface to avoid any unnecessary stagnated flow. The length of the fence and its location from the leading edge form two geometrical parameters. At any positive angle of attack, the resulting bounding streamline emanating from the leading edge and terminating at the tip of the fence is simulated by using suitable mathematical singularities subject to boundary conditions such as attaining a finite velocity at each critical point of the conformal mapping involved, and the condition of finite pressure gradient at reattachment, when applicable. Computational results from varying these two geometrical parameters indicate that the lift from each model is enhanced, as compared with the attached flow model around a simple flat plate and the original separated flow model by Kirchhoff.

If a plane oblique shock wave, inclined to the free stream at the angle ε, is produced in two-dimensional supersonic flow of Mach number M by (for example) a wedge which deflects the flow through an angle δ, the equation connecting these quantities may be written

In this form, δ is given explicitly when M, ε are fixed. Similarly, we may obtain M explicitly when ε, δ are fixed; equation (1) may be written (see, for example, Liepmann and Puckett, Equation 4.27)

For many conventional aircraft, the thickness of the wing and fuselage can be represented approximately by source distributions in the plane of the wing and on the axis of the fuselage. Such aircraft may be considered as having essentially planar thickness distributions. However, missiles with cruciform wings, biplane arrangements, “ ring ” wings and so on, require non-planar source distributions to represent the wing and fuselage thickness. For this reason, the term “ spatial thickness distribution ” is used.

To simplify the investigation of spatial thickness distributions, a singularity representing an element of volume is introduced. It is shown that the optimum distribution of such elements in a prescribed space gives rise to a minimum wave drag value consistent with that obtained for a Sears- Haack optimum body of revolution.

FFD (free-form deformation method) is one of the most commonly used parameterisation methods at present. It places the parameterised objects inside the control volume through coordinate system transformation, and controls the control volume through control points, thus realising the deformation control of its internal objects. Firstly, this paper systematically analyses and compares the characteristics and technical requirements of Bernstein, B-spline and NURBS (non-uniform rational b-splines) basic functions that can be adopted by FFD, and uses the minimum number of control points required to achieve the specified control effect threshold to express the control capability. Aiming at the problem of discontinuity at the right end in the actual calculation of B-spline basis function, a method of adding a small epsilon is proposed to solve it. Then, three basic functions are applied to the FFD parameterisation method, respectively, and the differences are compared from two aspects of the accurate expression of the model and the ability of deformation control. It is found that the BFFD (b-spline free-form deformation) approach owns better comprehensive performance when the control points are distributed correctly. In this paper, the BFFD method is improved, and a p-BFFD (reverse solution points based BFFD) method based on inverse solution is proposed to realise the free distribution of control points under the specified topology. Further, for the lifting body configuration, the control points of the p-BFFD method are brought closer to the airframe forming the EDGE-p-BFFD (edge constraints based p-BFFD) method. For the case in this paper, the proposed EDGE-p-BFFD method not only has fairly high parameterisation accuracy, but also reduces the expression error from 1.01E-3 to 1.25E-4, which is nearly ten times. It can also achieve effective lifting body guideline constraints, and has the ability of local deformation adapting to the configuration characteristics. In terms of the proportion of effective control points, the EDGE-p-BFFD method increases the proportion of effective control points from 36.7% to 50%, and the more control points, the more obvious the proportion increase effect. The new method also has better effect on the continuity of geometric deformation. At the same time, this paper introduces the independent deformation method of the upper and lower surfaces based on the double control body frames, which effectively avoids the deformation coupling problem of the simultaneous change of the upper and lower surfaces caused by the movement of control points in the traditional single control framework.

For many space applications, such as communication, weather, military, and scientific experiment satellites scanning precise regions, it is necessary to maintain a satellite in a fixed orientation relative to the earth. Unfortunately, a correctly positioned satellite deviates with time from this preferred orientation due to perturbing environmental forces. This explains considerable interest in libra-tional stability study in recent times.

Among the numerous methods developed for librational control, a passive technique depending on the gradient of the gravitational field has gained attention. Depending on the orbital distance, environmental effects, such as, aerodynamic, radiation, and magnetic torques, become significant compared to the gravity-gradient restoring moment. A need to determine the influence of these disturbing forces is thus evident.

A few of the outstanding problems connected with the design of tailless aircraft are discussed. The paper does not set out to be in any way a comprehensive dissertation of the whole field of tailless design, as it was considered that it would be more useful to concentrate on some of the recent problems which are exercising the minds of designers at the present moment.

Since the problems discussed are those which are currently causing some degree of speculation, it follows that in the majority of cases only possible means of solution may be suggested and only tentative conclusions drawn.

The fatigue life of a pin-jointed connection can be optimised by using a moderately high degree of interference between the loading pin and plate. Where a joint has to be assembled in confined conditions, difficulty may be experienced in inserting the interference-fit pin and one possible solution is to use a pre-assembled interference-fit bush in the plate, leaving only a light interference-fit pin to be pressed in on assembly of the joint. It is shown that a relatively thick bush of diametral ratio 4/3 will give a reduction in shear stress concentration factor for the plate comparable with that obtained with a solid pin, but that maximum benefit is not obtained with a thinner bush of diametral ratio 8/7. Where thin bushes are essential in order to maintain the ultimate tensile and fatigue strengths of the plate and /or the ultimate and fatigue strengths of the pin, the shear stress concentration factor for the plate is reduced as the modular ratio of bush to plate is increased and as the interference fit of the loading pin in the bush is increased.

The Sixteenth British Commonwealth Lecture, The Story of Indian Air Transport, by Mr. J. R. D. Tata, Chairman of Air-India International, was given before a distinguished audience on 18th November 1960 at the Institution of Mechanical Engineers, Birdcage Walk, London, S.W.1.

The President of the Society, Dr. E. S. Moult, C.B.E., B.Sc., F.R.Ae.S., M.I.Mech.E., presided at the meeting. Before introducing the Lecturer the President explained that hitherto the election of Fellows had been initiated by the Council and announced once a year but, under the new By-Laws, Fellowship was to be regarded as a position which could be attained by any qualified member who had reached a position of eminence and responsibility in the profession of aeronautics. At the same time it had been decided that the announcement of such elections should be made not just once a year, but on occasions such as this.

The names of 22 members who had been elected to Fellowship since May 1960 were then read out by the Secretary. (These names were published in the December Journal–Ed.)

After congratulating the new Fellows, Dr. Moult said that the British Commonwealth series of lectures started at the end of the War in 1945, and had continued annually until the present day. Throughout the years they had had a series of outstanding lectures on subjects associated with aeronautics in the Commonwealth, given by most distinguished lecturers. The stature of this lecture was set for all time in 1954 when His Royal Highness The Duke of Edinburgh addressed them on “Aviation and the Development of Remote Areas”. Now they were to hear about the growth of aviation in one of the great members of the Commonwealth. Air Transport in India was now thirty years old1 and there was no one more suited to tell the story of that thirty years than their lecturer, Mr. J. R. D. Tata.

Mr. Tata had been actively associated with this development all his working life. Indeed, it was true to say he had had a major part in it. He learned to fly in 1929 and personally flew the first scheduled transport service in India in 1932. He had been associated with aviation throughout all these years and a few years ago was president of I.A.T.A., the International Air Transport Association; he was now Chairman of Air-India International. He had great pleasure in asking Mr. Tata to give the Sixteenth British Commonwealth Lecture, “The Story of Indian Air Transport.”

In the first Cierva Memorial Lecture, Professor Bennett dealt with the life and work of Juan de la Cierva. He was priviledged to know Cierva personally and to work with him. He described in vivid detail the qualities of Cierva as a man and the many aspects of his work which contributed to the successful evolution of rotating-wing aircraft. The lecture was aptly titled “The Era of the Autogiro.” At the time of Cierva's death in 1936, the autogyro had been well established and the helicopter, which was to supersede the autogyro, was only beginning to show promise as a satisfactory flight vehicle. By the time I first became directly associated with rotating-wing aircraft, some eight years later, Cierva had already become one of the legendary figures of aeronautics.