Coupling of clearance joint and harsh aerodynamic heating environment is an inevitable nonlinear factor in folding mechanism of the fin of high-speed aircrafts that remarkably modifies natural frequencies and modes of vibration from the initial design state. However, accurately predicting dynamic properties of deployable fin with full consideration of these effects is not common industry practice. A practical semi-analytical model based on Hertz contact theory and ESDU-78035 model is proposed in this study to investigate high-temperature connection stiffness of local hinged–locked mechanisms. Material property degradation and clearance variation caused by thermal expansion are comprehensively considered and quantified in this model. Vibration characteristics of the assembled deployable fin are then solved using finite element method (FEM). The real-time evolutionary process of thermal mode of the fin is discussed. And natural frequencies of fixed-value and time-varying connection stiffness are compared. The simulation results of this study demonstrate that the relative error of structure temperature between the sequential approach and fully coupled simulations is less than 6.98%. The connection stiffness (slope of the load-displacement curve) of the folding mechanism under high temperature conditions decreases by 3.52%, and the variation is mainly caused by the degradation of the elastic modulus of the material, while the clearance change due to the thermal expansion has no significant effect on the slope. The natural frequency of the deployable fin exhibits an inverse correlation with the temperature change trend, and the first three frequencies decrease by 1.67, 7.75, and 16.28 Hz compared to the initial value, respectively.

In a recent paper (Ref. 1) Dr. Hilton proposed the use of manoeuvres for creating zones of “no boom” which could be employed to protect cities situated along the flight path of a supersonic aircraft. The basic idea was to make use of the fact that curved flight causes a local focus of shock waves and that, in regions closer to the centre of curvature than this focus, shocks do not form.

In investigating this intriguing suggestion, the author found it advantageous to abandon the Huygens-type construction used by Hilton and employ in its place a technique which permits plotting the shock front directly. In applying this approach to manoeuvres of the type proposed for shock avoidance, regions of single, double and even triple shocks were found, but no shockless region. The method used and the results obtained are outlined briefly in the following sections.

Calvert has considered alternative methods of estimating the blockage corrections for blunt-based bodies of revolution in closed wind tunnels at low Mach numbers. His models were all of maximum diameter 152 mm, with an ellipsoidal nose section 203 mm long followed by a cylindrical afterbody. The ratio of overall length L to maximum diameter d varied from about 1.5 to 5.5. For each model the base pressure was measured in wind tunnels of two different sizes, so that the blockage correction factor e for the smaller tunnel could be derived for each model from the experimental results. These experimental values of e were compared with alternative theoretical estimates, using the methods given by Evans, Maskell and Pank-hurst and Holder.

An Address by the President, Sir George Edwards, C.B.E., B.Sc, F.R.Ae.S., was given before a large and distinguished audience of members and their guests at Church House, Westminster, London, S.W.1, on 26th February 1958. Lord Hives, C.H., M.B.E., B.Sc, LL.D., Honorary Fellow, presided. At the end of the Address the second part of the Shell Petroleum Company’s film “High Speed Flight—Part II. Transonic” was shown for the first time.

Following the Presidential Address a Reception was held by the President and Lady Edwards at the offices of the Society, 4 Hamilton Place, W.1, which was attended by over 500 members and their guests.

The idea of using engine power directly to provide the lift required to sustain flight has recurred frequently throughout the history of aviation. Most of these proposals have concerned some form of helicopter, but in a few cases methods of changing the line of action of the normal propulsive thrust to assist the landing and take-off manoeuvres have been suggested. Few, if any, of these schemes were ever successfully put into practice, one of the main difficulties being the excessive weight and bulk of the power plant, but with the development of the jet engine with its compactness and low specific weight this objection largely disappeared and the idea was brought nearer the realm of practical realisation.

This paper is concerned with the rolling resistance, or drag, of an unpowered pneumatic-tyred wheel rolling at high velocities in soft soil. Its application is to undercarriage design for aircraft intended to operate from unsurfaced airfields, and to the inverse problem of predicting the performance of existing aircraft in such conditions.

This paper describes part of an investigation into the prediction and characterisation of limit cycle oscillations occurring in non-linear aeroelastic systems. Through the use of a modified version of normal form theory, it is shown how it is possible to predict the limit-cycle oscillations and characterise their stability. The approach is analytical and does away with the need for an excessive amount of time marching iterative numerical simulation of the system. The methodology is demonstrated upon a simple two degrees-of-freedom aeroelastic wing model with cubic stiffness. A good agreement was obtained between the analytical prediction and numerical simulations.

The aim of this article is to describe a method of power utilisation in a man-powered oscillating wing machine and to suggest features of design, which it is hoped might be of practical value to the many man-powered flight enthusiasts wishing to engage in what might, perhaps, become a relatively cheap and exhilarating sport.

With considerable expenditure of time and resources, successful attempts at man-powered flight have been made in the not so distant past. These exercises, at or near the limits of man's physical endurance, have been rewarded with flights lasting but a short while. And it is believed that any improvement of results in the near future can be only marginal.

The Sixth Louis Bleriot Lecture was given in London by General Guy du Merle on 19th March 1953 at the Institution of Mechanical Engineers, Storey's Gate, S.W.I. Mr. G. H. Dowty, F.R.Ae.S., President of the Society, presided and welcomed particularly M. Jules Jarry, President of the Association Francaise des Ingenieurs et Techniciens de l'Aeronautique, and members of A.F.I.T.A., who had come over from France for the occasion.

Introducing the Lecturer, the President outlined his career. After leaving school General du Merle went into the corps of aeronautical engineers, which was then of civil status but had since been militarised. He spent two years at the Ecole Nationale Supérieure de l'Aéronautique, graduating in 1932, and obtained his certificate as a pilot of military aircraft including seaplanes. For the next two years he served as an engineer pilot at the Centre d'Essais en Vol (Flight Testing Centre) testing prototype aeroplanes at Villacoublay, during which time he flew both French and foreign aircraft. He next became Engineer at the Technical Department of Aeronautics at the Air Ministry and then Director of the Department. While a professor at the Ecole Nationale Supérieure de I'Aéronautique he had published a book on the construction of aeroplanes, a copy of which was in the Library of the Society. Upon being attached to civil aviation at the Ministry of Public Works and Transport, he founded and directed for two years the National School of Civil Aviation at Orly. General du Merle was then appointed Director of Navigation and Air Transport at the same Ministry, and represented France at a number of international meetings on Civil Aviation. Appointed Ingénieur Général de l'Air, he had regained for a short time his original Ministry, which he now represented on the Interim Committee of E.D.C. He had been on missions to England a number of times since the end of the war, and in 1947 had flown several British aeroplanes, including the Sea Fury, the Meteor and the Vampire. He was a Fellow of the Royal Aeronautical Society, and was also an Officer of the Legion d'Honneur and held the Medaille de l'Aéronautique. General du Merle was at present Commandant des Ecoles et Stages at the Ministere des Travaux Publics et des Transports (Officer in charge of Schools and Courses).

A meeting of the Royal Aeronautical Society was held in the lecture hall of the Institution of Mechanical Engineers at Storey's Gate, St. James's Park, Westminster, London, S.W.1, on Thursday, March 8th, 1945, at which a paper on “Electrics for Aircraft,” by Mr. C. G. A. Woodford, A.M.I.E.E., A.F.R.Ae.S., was read and discussed. The President, Sir Roy Fedden, in the Chair.

We wish to propose that the word “receptance” should be used instead of “admittance” as applied to mechanical systems (see R. and M. 2,000, 1947). By this, we mean that if a generalised disturbing force Fse iωt is applied at the s th generalised co-ordinate q s of a linear oscillatory system, then the response at the r th generalised co-ordinate is given by

q s = αrs Fse iωt

where αrs is the “Cross-receptance” between q r and q s. If r = s, then αrs would be the “direct receptance” at q s.

The only simple method of estimating the tip speed limitations imposed on a rotor by retreating blade stall on the one hand, and compressibility losses on the other, is that given by Hafner. It suffers from the lack of accuracy always inherent in a “standard radius” method, and for present-day use a more refined approach is obviously desirable, provided that it still enables rapid estimates to be made.

For several years before 1976 the United Kingdom had been increasingly dissatisfied with the working of the old Bermuda Agreement. That Treaty had been a landmark in its day and its authors can be—and must be —proud that it stood the test of time so long. It had a profound influence on the development of post-war civil aviation and was the guiding light for numerous bilateral Air Services Agreements the world over.

But by the early 1970s its wording—possibly intentionally imprecise in a number of places—had become increasingly out of date and the subject of contentious argument. The Tariffs Article in particular gave continuing cause for trouble and the UK had become disenchanted with the working of the capacity provisions and dissatisfied in particular with the general balance of the Agreement. US airlines earned in the year ending 31st March 1976 nearly £300m from the Agreement whereas the earnings of British airlines was only some £130m. Of this latter figure, £127m was earned on the North Atlantic where US airlines earned upwards of £180m. It was self-evident that the American airlines would always outfly and out-earn us across the Pacific on routes to and through Hong Kong, and on routes between the mainland of the USA and Bermuda as well as to British points in the Caribbean. But it was not so self-evident that American airlines should continue to have a wide range of valuable fifth freedom rights at London and Hong Kong when British airlines could make no practical use of the relatively few fifth freedom opportunities which they had from points in the United States onwards across the Pacific and into the Caribbean.

The flow along the corner formed by two semi-infinite intersecting flat plates is considered in which the corner line is parallel to the streamlines of a uniform incident flow and a uniform suction is applied at the plate surfaces.

A knowledge-based computer system has been developed to automatically scan and interpret graphical displays of vibration data taken from strain gauges mounted on the blades of gas turbines performing acceleration tests. The various characteristic lines which appear on these displays are recognised and classified and the lines representing modes of vibration are examined to determine which mode is being excited and the severity of the excitation. All lines are compared, by a “blackboard” technique, against those predicted by the system working from the engine specification, laboratory tests and finite element analyses. Any unexpected features are reported for manual inspection.

Several series of tests have now been made on the system. In the first test on 130 diagrams, every one of over 3000 features visible to the human eye was detected and then classified.

We must thank Dr. Grzedzielski for the clarification of his argument and notation contained in his second note. Unfortunately, this note only shows more clearly the fundamental misconceptions and errors in his arguments. Our own argument as to the generality and validity of the initial strain concept remains unaffected.

In our previous note, we were concerned to explain the initial strain concept, which Dr. Grzedzielski had criticised as “ an oversimplification not generally admissible “ both in the calculation of thermal stresses and as a device to simulate the effects of structural cut-outs and modifications. Here, we prove independently by a direct consideration of the compatibility conditions in the final structure, that the modified stress distribution given by our analysis is the correct one—regardless of the extent of the coupling in the flexibility matrix.

Due to their high strength to weight ratio, sandwich panels have become increasingly popular in various areas of structural design. This is particularly true with the aerospace industry where high strength low density materials play an important role in the fabrication of major structural components. Along with the continual quest for strong lightweight structures, recent optimisation methods in structural design have led to a re-examination of the validity of the traditional conservative designs based on the usual linear assumptions of structural analysis and tend to adopt more realistic approaches incorporating geometric nonlinearity of the structure by using more exact finite-displacement, strain-displacement equations.