bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Developments in Aircraft Production
Authors: Robinson D. C.
Published: August 2016

With all transport vehicles a light structure weight is of prime importance. Light weight vehicles require less power to accelerate, less braking to stop, less power to climb hills. The power /weight ratio broadly determines the ability of a vehicle to get out of difficulties, avoid collision and, generally speaking, settles the vehicle's performance characteristics.

This is particularly true of the aeroplane where, with a third dimension of travel, the effect of gravity is present to a degree unknown to sea or land travel, even in mountainous countries.

Weight saving thus becomes of paramount importance in aircraft design and leads inevitably to the conclusion that nothing should be carried in the aeroplane to fulfil a service which can be satisfactorily and safely performed on the ground.

A further result, and one that most concerns us here, arises from this weight factor. In many trades a great deal of the technical execution of the work in detail is carried out in accordance with the superintendent's or foreman's knowledge and craftsmanship, and whether there is a little more—or less— material used is a matter for commercial considerations of cost, rather than one of necessity to save weight in order to fulfil performance.
The Selection of Engineering Personnel
Authors: Holliday Frank
Published: August 2016

This paper had not been easy to prepare because any adequate treatment of recent investigations and research would have to pre-suppose in the engineer-reader a whole body of information which it would not be reasonable to suppose he has. Further, the author's pitch had been cleared, for nearly three years ago the Institution of Production Engineers published a paper by him entitled : "A Survey of Selection and Allocation for Engineering Occupations."

After much thought, he decided to deal mostly with some of the fundamental ideas underlying selection, and to offer a bibliography to assist readers who so desire, to gain further knowledge of the underlying facts and theories of Occupational Psychology and of the application of these to investigations which have been carried out in the allied fields of vocational guidance and selection, and to procedures which are being increasingly used.
Beryllium, Beryllium Alloys and the Theoretical Principles Affecting Alloy Formation with Beryllium
Authors: Raynor G. V.
Published: August 2016

Beryllium, though of increasing application in the metallurgical and electrical industries, must still be classed as a relatively uncommon element. This would appear to be chiefly because no large scale application of the metal has yet been made; most commercial applications involve the addition of small amounts of beryllium to other metals, notably copper.

If a large scale use for beryllium were to be discovered, there would be little difficulty in the production of sufficient metal to fulfil a reasonable .demand. Its ores are widespread, but unfortunately are seldom found in heavy local concentrations. The processing of these ores is somewhat difficult on a commercial scale, but not prohibitively so. Extensive researches have been made on these problems, because of the incentive given by the exceptional “lightness” of beryllium, its high melting point and particularly, by its high modulus of elasticity.
Recent Aerodynamic Developments
Authors: Relf Ernest F.
Published: August 2016

It was with the greatest pleasure that I accepted the invitation of the Council to deliver the Wilbur Wright Lecture this year. Not that I count myself worthy to follow in the footsteps of the many illustrious men, British and American, who have delivered it in the past, but rather that I feel we are on the verge of discoveries and advances almost as spectacular as that flight of Orville Wright's, forty-three years ago, and that my peculiar experience may enable me to present to you some of the results of recent researches which have led me to the above somewhat prophetic conclusion.
Strength of Screw Threads of Whitworth Form
Authors: Inglesby J. V.
Published: August 2016

A Stress analysis of screw threads of Whitworth form has been performed.

The critical stress in the threads is a shear stress, and this may be expressed simply in the form:–

where

Smax=shear stress.

f=distribution factor.

= 1.0 when screw and nut are both in tension or compression.

= 2.0 when screw and nut are in tension and compression respectively, unless specially designed for an improved distribution of load.

k = coefficient, depending mainly on fit, but also on pitch of threads, L and D.

<0.8 for close fit.

<0.9 for medium fit.

<1.0 for free fit.

P=axial load.

L=length of engagement.

D=nominal diameter.
Analysis of Stress Strain Curves
Authors: Voce E.
Published: August 2016

It is gratifying to learn from Mr. Nicholls (May 1955, p. 364) that he is favourably impressed with the exponential function, and it is to be hoped that he, and others interested in stress-strain relationships, may find it to be of practical value.

While the modifications which he suggests are quite legitimate, they tend to mask the essential simplicity of the function. It would be difficult to obtain the asymptotic stress from his first equation. The second can be easily solved for strain, but the converse process is complicated by the fact that the current stress appears both inside and outside the exponential. It is surely much more straightforward, and infinitely quicker, to plot the stress-strain curve from the proof stress data and analyse it in the normal way.
Aeroplane Wheels and Tyres
Authors: Walters N.
Published: August 2016

The first requirement in any manufacturing process is to secure a stable raw material, and to this end scientific control was essential, for it was found that the rubber obtained from trees on the top of a hill differed from the trees in the same field or plantation at the base of the hill. A process of blending was therefore essential.

The pure rubber was rolled and crushed so that it became a “ flannelly ” sheet of crêpe rubber such as is used on tennis shoes, etc., but in this form the rubber becomes sticky when heated. Filling agents are therefore added, and colouring materials to give the red tint for inner tubes and grey for outer covers.
Practical Training of Aeronautical Engineers
Authors: Hahn J. M.
Published: August 2016

The Men who could best lay claim to the title of “Aeronautical Engineer” were the early pioneers like Wilbur and Orville Wright. They were their own research workers, their own designers, their own draughtsmen, their own constructors, their own test pilots and, later on, their own salesmen. The Wright brothers carved and steamed the bamboo ribs and struts of their aeroplane themselves, brazed and spliced the wires and cables, while their sister Kathleen stitched the flimsy fabric. But the day of the craftsman-designer is gone.

This paper is concerned with the present-day professional aeronautical engineer in industry and in particular, with the aircraft designer. A distinction must be drawn between the aeronautical engineer and the aircraft technician; both may be intimately concerned with the design of an aeroplane, but the technician—the stressman, the aerodynamicist, the draughtsman—is at the most an embryo aeronautical engineer.
The Military Aero-Engine-is it Suitable for Civil Aviation?
Authors: Bailey S. B.
Published: August 2016

In the past, the majority of civil aircraft have been powered by engines which have been developed primarily for the Royal Air Force. Their development costs have been borne by the Service departments, and then they have been converted for civil use at comparatively small extra cost.

It has always been questionable whether these converted engines have been really suited to their civil role, and it will become even more doubtful the farther the design and performance of civil aircraft depart from those of military aircraft.

In this paper, an attempt has been made to coyer the more important requirements for the two kinds of engines, and to see how they compare. If it appears that too little has been said concerning the gas turbine, that is because there is as yet no experience of its commercial operation.

The opinions expressed in the paper are the author’s and have no official significance.
Electric Resistance Welding and Its Use in the Construction of Aircraft
Authors: Sykes E. C.
Published: August 2016

Designers and technicians pay a great deal of attention to the development of jointing methods for use in the construction of aircraft. A satisfactory method should be neat, economical in labour, flexible in application, and capable of yielding consistent results with a low weight penalty.

Electrical resistance welding meets the above requirements and it is with this process that I shall deal.
Structural Features of German Aircraft
Authors: Leggett D. M. A. , Davison J. H. H.
Published: August 2016

Although this paper is primarily concerned with the structure of current German military aircraft, no apology is needed in considering for a few moments some of the outstanding developments that took place 20 or 30 years ago.

In the early days of any branch of engineering, there are always a few individuals in each country who stand head and shoulders above their fellow workers in the same field, and aviation is no exception. But, whereas in this country quite a number of people spring to mind as having made exceptional contributions to aeronautics, in Germany one name stands out pre-eminent— that of Junkers. Hugo Junkers was born in 1859 and soon showed promise as a scientist and engineer. His technical training was varied, and at the age of 36 he founded at Dessau the engineering firm which bears his name.
Planned Flying and Planned Servicing in the Royal Air Force and the Effects of Aircraft Design on Maintenance
Authors: Harrop E. A.
Published: August 2016

The 767th Lecture was read before the Royal Aeronutical Society on Thursday, 17th February 1949, at the Institution of Civil Engineers, Great Georgr Street, London, S.W.1. Dr. H. Roxbee cox, D.I.C., F.R.A.e.S., President of the Society introduced the Lecture Squadron Leader E. A. Harrop, O.B.E., A.F.R.Ae.S., R.A.F., of the Department ot the Air Member for Technical Services, Air Ministry, and a serving engineer officer of long experience in the Royal Air force.
Inter-City Transport Development on the Commonwealth Routes
Authors: Atkin E. H.
Published: August 2016

The Fifth British Commonwealth and Empire Lecture was given before the Royal Aeronautical Society by Mr. E. H. Atkin, B.Sc, F.R.Ae.S., on the 15th September 1949 in the Lecture Hall of the Institution of Civil Engineers, Great George Street, S.W.I. Sir John Buchanan, C.B.E., F.R.Ae.S., President of the Society, presided.
Evaluation of Aeroplane Metals
Authors: Van Den Broek J. A.
Published: August 2016

The material herein presented was gathered as part of a research project for the Bureau of Aeronautics (Structures Branch) of the U.S. Navy on “Evaluation of High Strength Aluminium Alloys.” The Bureau has released this material for independent publication.

In this paper the physical constants determined are limited to elastic limit, yield stress, ultimate stress, modulus of elasticity, weight and ductility. The materials tested are primarily the new aluminium alloys 75 ST, R 301 T, and R 303 T.

To offer an immediate basis of comparison for aluminium alloys, the aluminium alloy at present in common use, namely 24 ST, was also tested. To extend the scope of the project still further, a few tests on magnesium alloy and stainless steel were included.
The Stresses in a Circular Fuselage
Authors: Goodey W. J.
Published: August 2016

The following investigations were made primarily in order to determine the manner of transmission of concentrated loads from the frames to the skin of a circular fuselage. The usual assumption, that the shear distribution in the skin adjacent to the frame is given by the simple “ beam theory,” was considered to be of doubtful validity, and for some time past the writer had suspected that a critical examination of the problem would show a very considerable variation from the ordinary theory in the immediate vicinity of the loaded frame. The writer's attention was first drawn to the problem by the work of Wignot, Combs and Ensrud in N.A.C.A. Technical Note No. 929, and the present investigations were made because a more fundamental approach to the subject was considered to be desirable.
The Aerodrome Problem Related to Aircraft Design and Operation
Authors: Ayers R. H.
Published: August 2016

The Aerodrome, as the point of contact between the aircraft and the world of reality, has to a large extent been taken for granted. The designer regards it as the base for prototype tests and the airline operator as his aerial railway station. It is my intention to show that aerodrome development is at a critical stage of evolution on this side of the Atlantic, that many of the related problems do concern the aircraft designer and operator, and that if these problems are not given consideration, difficulties will be encountered in civil operations.

To quote an example; the optimum aircraft type to serve a system of air routes can be worked out taking into consideration the range required, payload and speed, but if the aircraft ultimately ordered and produced cannot safely operate from the aerodromes to be served because of the runway length and approaches, then the operations will either have to be reorganised or continued without due regard for safety.
Thirty-Second Wilbur Wright Memorial Lecture
Authors: Roy Fedden A. H.
Published: August 2016

Earlier sections have dealt with engines which have been developed almost entirely with the object of war and destruction. The fighter engine has been pushed all the time harder and harder to obtain greater output, with increased rate of supercharge, higher critical altitude, and more power to manœuvre under all possible conditions and attitudes of the aircraft. Performance has been achieved at almost any expense, provided reliability was ensured for a given period; such items as the time between overhaul and fuel consumption have been secondary considerations. In a similar way bomber engines have been continually stepped up in power to give maximum output at rich mixture for takeoff, so as to project the greatest possible load of bombs into the air, and every attention has also been given to providing the highest weak mixture cruising power at altitude, in order to allow for the necessary power to maintain flight at a reasonable altitude during the early part of the mission, when the machine is fully loaded.
The Problems of Blind Landing
Authors: Pritchard H. C.
Published: August 2016

In being honoured by the request to deliver a lecture on “ The Problems of Blind Landing,” I am set to some extent a task different from that normally presented to the Society's lecturers. In general the results of successful research are presented to you, whereas I am merely asked to outline the problems — with the implication that constructive suggestions for their solution may result. Personally, I feel that this is a most appropriate type of lecture, particularly in regard to a problem which embraces specialist fields in radio and radar, in aerodynamics and aircraft instruments, to an extent that few can claim to be expert in all.

The problem of blind landing can best be discussed after reviewing existing methods of blind approach and proposals now current for solving the landing problem.
The Development of the Spitfire and Seafire
Authors: Smith J.
Published: August 2016

The object of this paper is to discuss the evolution of the wartime fighters the Spitfire and Seafire, designed by the Supermarine Works of Vickers–Armstrongs Ltd. In particular, it will be confined to the design and technical side of the problem. The production undertaking, which resulted in the manufacture of over 22,000 of these aircraft in 33 different types, would undoubtedly need a paper of its own.

In order to make the matter clear it is proposed to begin with a brief history of the early development of high speed aircraft by the firm. The next logical step is to survey the Spitfire family as a whole and to trace the relative importance of the different types, giving some indication of their line of development. Finally, an attempt will be made to analyse the factors which maintained the efficiency of these aircraft at a high level for a period of ten years.
Ball and Taper Roller Bearings
Authors: Frenkel M. S.
Published: August 2016

This analytical treatment gives general considerations concerning “ true rolling ” of a rolling body in a circular path : firstly, for constant speed of its centre of gravity, and, secondly, for acceleration of its centre of gravity. From these are derived the relations of the dimensions, as function of the conditions, and the corresponding constructions for both taper roller bearings and ball bearings, which are essential to produce “ true rolling” at constant and variable shaft speeds.
Progress Towards Electrical Serviceability
Authors: Woodall R. H. , Higgs V. A.
Published: August 2016

The 820th Lecture to be read before the Royal Aeronautical Society, “Progress Towards Electrical Serviceability,” was given by R. H. Woodall, M.I.E.E., A.F.R.Ae.S., and V. A. Higgs, B.Sc., A.M.I.E.E., A.F.R.Ae.S., on 1st March 1951 at the Institution of Civil Engineers, Great George Street, S.W.I. Major G. P. Bulman, C.B.E., F.R.Ae.S., President of the Society, presided at the meeting and introduced the lecturers. Mr. Woodall is a Director and Chief Engineer of Rotax Ltd., and Mr. Higgs is Head of Technical Sales and Aeroplane and Automobile Sales of the British Thomson-Houston Co. Ltd.

It is evident from remarks made in previous papers or in discussion on those papers, that the Aircraft Industry is not entirely satisfied with the electrical accessories available for use in aircraft.

There may be some grounds for this dissatisfaction, but it is hoped to make it clear that the electrical equipment suppliers are very much alive to their responsibilities and that development on an ever-increasing scale is taking place in order to give the aircraft constructors the most reliable equipment possible.
A Note on the Load Transference on Multi-Wheel Bogie Undercarriages
Authors: Collinson E. G.
Published: August 2016

In multi-wheel undercarriages the application of the brakes not only affects the total load on the undercarriage, due to transference of some load to the nose wheel, but there is also a local transference between the wheels of the bogie itself. This note calculates these loads and gives two methods of preventing excessive overload of the tyres.
Estimation of Cruising Air Speeds for Economic Analysis
Authors: Stratford Alan H.
Published: August 2016

In the course of investigation into the operating economics of transport aircraft, the cruising speed arises as a fundamental variable and a rapid method of correction of speed for variation of power, height and weight is frequently required. Other problems present themselves, such as the estimate of cruising speeds in the course of a new type design study, or the correction of a “one–point” published performance of a new aircraft to a standard operational condition differing in specified weight, altitude or power output for cruising.

In this note no account will be taken of the block speed correction arising because of the modification of true air speed by the various factors, such as wind, climb and glide which distort the optimum flight path. The principle of the method here suggested involves the unique relationship of p, the ratio of thrust power required at any speed (V) to the thrust power at the minimum drag speed (u) at the same altitude, and n the wellknown speed ratio V/u.
The Design and Production of Japanese Military Aircraft
Authors: West Alex P.
Published: August 2016

In January, 1946, the writer was fortunate in being chosen as a member of a Scientific Mission sent to Japan by the Australian Commonwealth Government. As a member of this Mission he was required to investigate and report on the standard of design of military aircraft being produced by the Japanese at the end of the war.
Aircraft in Agriculture
Authors: Southwell P. H.
Published: August 2016

The application of aircraft to agriculture began in the 1920's; experiments in insecticide dispersal were made in Ohio in 1921 and a bulletin was issued by the U.S. Department of Agriculture on dusting cotton crops by means of Curtiss JN6H aeroplanes in 1924. Since then the idea has been developed, notably in countries of large area. In 1928, for example, crop dusting experiments were made in the United Kingdom but the results were not very encouraging because of the drift problem with comparatively small fields.
The Development of All–Wing Aircraft
Authors: Northrop John K.
Published: August 2016

In choosing the title, “The Development of All–Wing Aircraft,” as the subject of my lecture I run some risk of being accused of writing a company history rather than a paper of the broad scope ordinarily presented before this time–honoured institution. This is far from my intent, but being sincerely convinced that the all–wing aeroplane is a valuable step in the development of aeronautics, and desiring to contribute a maximum amount to the available data in the limited time at my disposal, my paper must be confined largely to experience gained by our company in its work on this subject.
A Shortened Method for the Calculation of Aerofoil Profile Drag
Authors: Dowlen E. M.
Published: August 2016

A rapid method is developed for estimating the profile drag of an aerofoil with a known transition point position. The results are in good agreement with previous calculations.
Problems of Transonic Flight
Authors: Clifton A. N.
Published: August 2016

The title of this paper may be said to cover almost the whole field of the immediate endeavours of those who are concerned with the design and technical development of military aeroplanes, and especially of fighters. The term transonic is not precise, but may be defined conveniently as applying to those speeds of flight, in the region of the speed of sound, when all the customary aerodynamic design rules cease to operate. Theoretically, therefore, transonic flight consists entirely of problems.
Fatigue in Engine Design
Authors: Owner F. M.
Published: August 2016

The difference in outlook between metallurgist, physicist and designer on the problem of fatigue of metals is due not only to the differences in training and method but also in immediate objective, however closely their ultimate objectives may coincide.

Physicists consider fatigue in terms of crystal structure and composition of the constituents of the crystal, noting in passing that certain types of crystal structures are associated with poor fatigue strength. The metallurgist's prime interest lies in the effect of surface finish, heat treatment, the physical condition of the surface, such as degree of cold work, the effect of carburised and nitrided cases having different hardness from the core. Both think in terms of controlled condition tests, with idealised test conditions such as cylindrical test specimens, close control of changes of section, polished surfaces of only a few micro-inches surface roughness, operating in a controlled atmosphere.
Aeronautical Research in the Netherlands
Authors: Van Der Maas H. J.
Published: August 2016

It is a great honour to be invited to present a survey of the aeronautical research in the Netherlands to this distinguished audience and I wish to express my thanks to the Council of the Royal Aeronautical Society for giving me the opportunity to deliver this lecture. The more I appreciate it in view of the friendship between our two countries, between the Society and its Dutch counterpart and the personal friendship with so many present on this occasion.

It is my intention to give a survey of some of the work performed in the Netherlands in the post-war period and to describe briefly the main installations which are now available or under construction. I hope that I will be able to give you an impression of the scope and the nature of the aeronautical research activities in the Netherlands. These activities are being directed in the first place by the immediate needs of the industry and the aircraft operators; and in the second place by the desire to contribute to the general development of the art, thereby also supporting the exchange of results on an international basis, even more essential than before, considering the rapidly growing importance of aviation in its broadest sense.

Before entering into more technical matters it may be worthwhile to give very briefly an outline of the present organisation of aeronautical research and development in the Netherlands.
A Test Plant for Helicopter Engines
Authors: Walker A.
Published: August 2016

This Note describes the design and construction of a “ Tilting Test Bed ” for helicopter engines for Alvis Ltd., for which some onerous requirements were laid down (Fig. 1). The most important of these were that:—

(i)

Readings of engine torque and b.h.p. must be given by a dynamometer, so as to provide accurate data.

(ii)

The engine, and therefore the complete test plant, must be capable of being tilted, while running, through 120°—from the horizontal to the vertical and 30° beyond.

(iii)

During the tilting process the engine throttle setting must remain unaffected and the readings of torque, b.h.p., fuel consumption, and so on, continue with unaltered accuracy.

(iv)

A powerful fan must be incorporated, for cooling certain types of engine not provided with selfcontained fan, and the air-blast must continue unchanged during tilting.
Problems of Servicing and Reliability
Authors: Buxton G. M.
Published: August 2016

There are two parts of this paper, the first dealing with Servicing and the second with Reliability. Although they are connected in many ways, and indeed servicing has been taken to mean checking parts which might be unreliable, it is convenient to separate them.

A practical factor of increasing importance is the burial of the accessory machines in modern aeroplanes.

Compared with, say, a plough, the parts of Blériot's Anzani engine might be thought to be dangerously concealed; dangerous, that is to say, if its working depended on any condition of the internal parts which could be judged when looked at. But the Anzani engine was simplicity itself, compared with any modern machine, even an accessory machine, and these machines are usually covered by, or rather entangled in, the structure.
An Application of Carpet and Lattice Plotting
Authors: Tatham R.
Published: August 2016

The carpet and lattice methods of plotting the relationship between three and four variables respectively, developed by R. F. Sargent, of the National Physical Laboratory, have been described previously by A. H. Yates, who gave examples related to the presentation of aerodynamic and engine performance data. Outside these fields there appears to be still some lack of appreciation of the usefulness of this form of graphical representation, although it is capable of wide application. The writer has found both carpet and lattice plotting of great value in connection with the preparation of structures data sheets, and is convinced that interpolation is generally rendered easier and more accurate if graphical data are presented in this way. In one particular instance it was found possible to develop a nomogram in the form of an “ extended lattice ” plot, which gave in graphical form a direct solution to a set of equations which could be solved otherwise only by continuous approximation.
The Local Instability of a Simple Integral Panel
Authors: Chilver A. H.
Published: August 2016

The local instability of a simple type of integral panel under uniform end compression is discussed firstly as a problem of interconnected flat plates, and secondly in terms of the torsional stability of the stiffeners. It is found that the second method under–estimates the “true” local buckling stress. This conclusion is in conflict with earlier work by Yusuff on closer study it is found that Yusuff's analysis involves two important assumptions which are generally unjustifiable. It is suggested that the collapse strength of a short compressed panel may be estimated with reasonable accuracy from a knowledge of the initial local buckling stress and the proof stress of the material of the panel.
The Pressure Distribution Due to Incidence on a Slender Elliptic Half–Cone
Authors: Taylor C. R.
Published: August 2016

The slender–body solution for the flow about low aspect–ratio wings of non–zero thickness yields a pressure distribution which is valid in the vicinity of the leading edge and therefore suitable for comparison with measured distributions. In this note an expression is derived for the theoretical pressure distribution, due to small incidence, on a slender elliptic half–cone in uniform motion. It is shown that this distribution is additive to the zero incidence pressure distribution. A comparison with some low speed measurements shows qualitative agreement.

The method can be simply extended to other bodies of elliptic cross section.
Graphical Analysis of Trans-Canada Airlines' Progress on the North American Routes 1946–1950
Authors: Jaworski Adam
Published: August 2016

Progress of any organisation may be related either to an assumed basis within the organisation itself, or to some other organisations, preferably competitors in the same business. The second method is more realistic and by relating the corresponding data in ratios, it helps to eliminate to a great extent the influence of price changes, which distort yearly comparisons of revenues and expenses.

In the United States the trunk lines represent over 95 per cent. of the total revenue ton-miles flown on the domestic routes and in international aviation, the largest system with the highest quality of service. Therefore, by comparing in Part I the domestic services of Trans-Canada Air Lines (T.C.A.) to corresponding services of the U.S. trunk lines, the most severe criterion was chosen.

Part II contains an investigation of trends of particular expenses in relation to the total expenses for T.C.A's North American Services.
Certificate of Airworthiness Flight Testing
Authors: Davies D. P.
Published: August 2016

Under the heading “C. of A. Flight Testing” many different subjects could be discussed; most of them, however, and particularly those concerning procedures and basic philosophies, are well understood and need little elaboration: the interest really lies in those items which regularly give trouble and, if I may borrow the current American expression, these “ problem areas ” form the basis of this paper.

In the time available I cannot hope to cover the whole picture and must limit myself generally to the large transport aircraft and, apart from one or two divergencies, to qualitative handling. The paper is my own and I take responsibility for the opinions expressed in it.
Cumulative Damage in Fatigue—A Design Method Based on theS-NCurve
Authors: Levy John C.
Published: August 2016

It is suggested that a convenient way of presenting the results of fatigue tests in which two different stress amplitudes are applied alternately is to plot log N against log (n1/n) where N is the total cycles to failure and (n1/n) is the fraction of cycles run at the high stress.With these co-ordinates, a simple geometrical construction gives a safe design method for the two-stress level system using only the conventionalS-Ncurve and the value of (n1/n) expected to be encountered in service. IfN1andN2are the lives at the high and low stresses as read from theS-Ncurve, one point may be plotted at (log N1, 0) since this represents the programme when all cycles are at the high stress. On the assumption, shown to be justified, that less than one cycle of high stress per 10,000 total cycles would not significantly affect the life at the low stress, a second point is plotted at (log N2, 4). The straight line joining these two points is always found to predict safe values of N for any value of (n1/n).This conclusion is checked against a wide range of experimental results taken from six different sources in the literature covering rotating-bending and push-pull tests, ferrous and non-ferrous metals, any order of stressing and length of programme cycle from 50 up to 5 million. This last feature means that the length of the programme cycle in service need not be known. All that is required is the proportion in which the two stress amplitudes are mixed. The average value of the ratio (experimental life/predicted life) for the data examined is 1·8, the extreme values being 1 and 56. By plotting in three dimensions an equation is also developed for the three-stress level spectrum and a suggestion is made for an extension of the method to multiple stress levels.
A Method of Measuring Post-Yield Strain
Authors: Woodcock F. J. , Weiss K. R.
Published: August 2016

Increasing interest has been shown recently in the measurement and interpretation of post-yield strains. Early investigators determined the nature and magnitude of such strains by observing the distortion of a grid of fine lines inscribed on the unstrained metal. A development of this method involved the use of a photographically deposited grid.

In the present instance the initial requirement (August 1948) was for the measurement against time of strains of the order of 4 per cent. occurring as “ fast transients.”

As the wire resistance strain gauge element was well established, it was natural to consider its extension to post-yield measurements, and it later became apparent that this had already been done by Swainger.
Experiments With Flat Planes (1866–1890)
Authors: Pritchard J. Laurence
Published: August 2016

The pioneer rarely receives that meed of praise which is his due, until those days arrive when his pioneering has become a page or so of history. What meed of praise he may then receive is too often made savourless by critics unable to disassociate themselves from the knowledge of their own technical era. The halting speed of pioneering aerodynamic research cannot be judged by the supersonic speed of secret splittings of the atom.

It was R. L. Stevenson who said that to travel hopefully is a better thing than to arrive. In aviation we have arrived at that streamline flow of technical jargon which deludes so many they have at last reached the boundary layer of aeronautical knowledge, so that they find experiments with plates always a little flat, although their curiosity may still be aroused by flying saucers.
Some Comments on High-Lift Testing in Wind Tunnels with Particular Reference to Jet-Blowing Models
Authors: A. Anscombe  , J. Williams
Published: August 2016

This paper considers some of the special problems of wind tunnel testing which arise in high-lift work. Discussion is confined to current experience in the R.A.E. and N.P.L. low-speed wind tunnels, and refers mainly to tests on blowing over flaps or jet-flaps. Comments are made on suitable size of model, methods of feeding compressed air into models without affecting balance readings, and general test technique. Methods of model construction are not specifically discussed.
A Specification for Engineering Education
Authors: Collar A. R.
Published: August 2016

So much has been said in the past four or five years of the need for Great Britain to increase the numbers of her trained scientists and engineers, and so much emphasis has been put on training by industry, that the country as a whole is aware, if somewhat vaguely, of the urgency of the present national need. Whether there is a real awareness of the continuing nature of the need, is, however, far less certain; and I make this my apologia for attempting some further discussion of a position which, to engineers at least, is at present patently and painfully obvious. It must be remembered that only a few short years ago, engineering skill was at a discount and the engineer something of a social pariah; moreover, the higher his academic training, the further he was beyond the pale.
The Vibrations of Laced Turbine Blades
Authors: Ellington J. P. , McCallion H.
Published: August 2016

While the use of blade lacing wires or shrouding is not altogether common in gas turbine practice, occasions may arise when their use is desirable, and the purpose of this note is t o present a method whereby the vibrational characteristics of a number of blades wired together may be conveniently found.
The Effect of Structural Damping upon the Stresses due to Jet Efflux
Authors: Mead D. J.
Published: August 2016

The reduction of the vibration amplitudes of a system subjected to external exciting forces can often be achieved by a suitable alteration in the mass or stiffness of the system. The natural frequencies of the system are thereby changed and are no longer in the neighbourhood of the peak harmonic components of the exciting force. This procedure can be shown to have little effect on the problem of jet efflux excitation (unless a really radical change of stiffness is made, such as could only be obtained by a complete change in the type of construction). This is due to the jet efflux pressure field having a fairly flat pressure spectrum and therefore containing harmonic components of all frequencies (over its range of flatness) which are more or less equal in magnitude. However, despite this flatness the spectrum of the generalised force exciting a particular mode has a large peak at the frequency where the sound wave of that frequency has the same wavelength as the structural mode (the coincidence effect).
Stresses Produced in Aircraft Structures by Jet Efflux
Authors: Clarkson B. L.
Published: August 2016

The sound pressures, associated with a jet efflux, set up stresses in an aircraft structure which are essentially those occurring in the resonant condition of the structure. These sound pressures contain components in a wide range of frequencies and the resultant stresses in the structure have low magnitude by normal structural standards but, because of the high frequency, they are very important from the fatigue standpoint. A rigorous theoretical approach is being developed at Southampton University which, although extremely difficult to apply to actual aircraft structures, emphasises the factors which must be considered. However, for immediate practical use it is suggested that an approximation can be made to render the problem tractable. It is considered that in an actual aircraft the effects are primarily local and on this assumption an approximation is developed and compared with test results. Reference is made specifically to the de Havilland Comet aircraft.
A Note on the Problem of Aileron Reversal at Transonic Speeds
Authors: Hunn B. A.
Published: August 2016

The problem of aileron effectiveness when the elastic properties of the wing structure are taken into account has already been adequately covered in the subsonic regime by A. R. Collar and E. G. Broadbent. The method used depends upon strip theory which pre-supposes a knowledge of the relevant aerodynamic derivatives. A unified method has been considered by the present author which employs either the semi-empirical theory of D. Küchemann or the lifting surface theory of H. Multhopp in such a manner that the effective values of the relevant derivatives are found, together with the rolling efficiency.
The Elimination of Wall Effects in Axial-Flow Compressor Stages
Authors: Stephenson J. M.
Published: August 2016

Compressor stages are usually designed on the assumption that the gas velocity is nowhere affected by the friction at the walls. The only way in which viscosity is taken into account is in the assumed efficiency, and in a guessed “work-done factor,” which ensures that by aiming high the required work is actually attained.

It is known that the radial profile of the axial velocity component becomes more and more peaked through successive stages of a compressor, so that the assumptions just quoted become very inaccurate. It is possible that the efficiency of a stage could be raised considerably if the axial velocity profile were controlled; moreover up to 20 per cent. more work could be done if a “ work-done factor ” did not have to be applied.
Definition of Specific Impulse
Authors: Greenwood S. W.
Published: August 2016

In Rocketry, the definition of Specific Impulse is given variously as Thrust per unit mass of propellants consumed per second and Thrust per unit weight of propellants consumed per second. The second definition is convenient in giving units in seconds, but is unsatisfactory in that the weight of a given mass of propellants depends upon gravitational attraction, and decreases with altitude.
Design for Production
Authors: Keen E. D.
Published: August 2016

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.
Reinforced Elliptical Holes in Stressed Plates
Authors: Hicks Raymond
Published: August 2016

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.
Fundamental Frequencies of Arbitrarily Shaped Simply-Supported Triangular Plates
Authors: Klein Bertram
Published: August 2016

A simple set of curves is presented from which may be calculated the lowest natural frequency of flexural vibration of practically any triangular plate of constant thickness and with simply-supported edges. In many cases the results are self checking since the calculations usually may be carried out in three independent ways and compared.
Dynamical Forces in Aircraft Engines Some Observations on Major Carter’s Paper
Authors: Morris J.
Published: August 2016

Major Carter has dealt with this question in his paper. He has originated a method and invented an expression. With his “resonance factor” as weapon he has started a crusade against the enemy and sees prospects of converting him into a friend.
Plastics Structures
Authors: Hulbert G. C.
Published: August 2016

More than two years ago Pollard in a paper given to the Society made out the case for the use of fibre-reinforced plastics in the structural field. He and others have shown that materials based on strong, inert fibres, such as glass or asbestos, have mechanical properties which, when stabilised by suitable resins, permit them to function with a high degree of efficiency within certain well defined parameters of loading.

Four distinct groups of resin are used in combination with such fibres, phenolic, polyester, epoxide and silicone. With the present exception of silicone resins, each can be used at low or even contact pressures during moulding and thus do not impose serious processing limitation upon the size, quantity or complexity of the structures which can be contemplated.
Air-Cooled Engines in Service
Authors: Fedden A. H. R.
Published: August 2016

It is now rather more than three years since I last had the honour of presenting a paper before this Society dealing with air-cooled aero engines. At that time the air-cooled engine had not fully won a place “in the sun,” which may be fairly stated to be the case to-day.

For some years after the war there was a considerable aversion towards the air-cooled aero engine owing to certain types which had been developed during the war which were supposedly air-cooled, but in reality obtained the greater portion of their cooling by means of exorbitant fuel and oil consumption. As lately as four years ago the practical advantages of the air-cooled engine were only tentatively appreciated by the aircraft constructor, and naturally, owing to his somewhat painful experiences in the past in respect of unreliability and high fuel consumption; it required some missionary work and proof in order to persuade him that the new family of air-cooled engines would really perform in the way their designers claimed for them.
Some Laboratory Methods of Aerodynamic Investigations
Authors: Tanner T.
Published: August 2016

The science of aerodynamics consists in the study of the phenomenon following upon the motion of a body through air, the object being to investigate the nature of the forces brought into action and to discover the reasons for these forces. We know from experience, for instance, that under certain conditions an aeroplane wing fails to exert sufficient lifting force to keep the aircraft in steady flight. From experiment it has been found that these conditions correspond to a breakdown in the flow of air over the upper surface of the wing,, and if we can discover some means of preventing this change we have, at least, served some useful purpose.
Engine-Airframe Integration
Authors: Nicholson L. F.
Published: August 2016

In this paper the subject is considered from an aerodynamic point of view and no discussion of the possibilities of structural integration of the engine and airframe in the sense of using parts of the engine to contribute to the structural strength or stiffness of the airframe is included, beyond the statement that the simplest consideration and roughest calculations suggest that the sort of deflections obtained on typical aircraft structures at full load do not seem compatible with the integration into such a structure of engines having rotating parts and fine clearances, although in the case of units such as ram-jets such structural integration may well be practicable and desirable. Another structural problem which leads naturally to the consideration of engine and airframe as a single unit is the problem of improving flutter characteristics by placing the concentrated masses of the engines in suitable positions relative to the wing.
Note on the Motion Inside a Region of Recirculation (Cavity Flow)
Authors: Squire H. B.
Published: August 2016

It is shown that the flow in a region of recirculation may be divided into a core, in which the vorticity may be constant, and a boundary layer surrounding the core. An approximate solution is given for the flow inside a circular cylinder with partly fixed and partly moving walls.

Flow patterns which include regions of recirculation occur frequently, for example, behind bluff bodies, in sharp bends, and in sudden expansions in ducts. Little is known about this type of flow, which will be referred to, for brevity, as ‘cavity’ flow. It used to be thought that the velocities in the ‘ cavity ’ were small compared with the stream velocity, but it is now known that the maximum velocity in the cavity may be about 30 per cent. of the stream velocity. This implies that the motion within the cavity cannot be neglected.