bluuebunny/crossref_metadata_2025 huggingface dataset:
Operational Research and Aviation Management
Authors: Longton P. A. , Williams A. T.
Published: July 2016

The previous paper in this series described what operational research is and illustrated some of its methods. The succeeding articles are concerned with considering some of the problems in the different branches of the aviation industry and showing how OR may be profitably applied to them.

This paper and the next form a continuous narrative. They differ in that the first concentrates on capital investment programmes and the procurement of aircraft, while the programmes and the procurement of running an airline. In the first, a discussion of cost structure leads on to some detailed models. A further series of models forms the basis of the second.
Design and Development of Small Aircraft Gas Turbines in France
Authors: Szydlowski Joseph
Published: July 2016

To Describe the development in France of small gas turbines of necessity confines one to the products of the Turbomeca Company. It is therefore not through lack of modesty that I speak of those engines which have been designed and built under my direction.

After the Second World War our aims were quite ambitious. We envisaged the creation of jet engines up to 6000 kg (13200 lb) thrust, as well as the aircraft to suit. We soon realised that such ideas were far beyond the industrial and financial possibilities of the time.
Stresses in a Square Plate Having a Central Circular Hole
Authors: Davies C. A. O.
Published: July 2016

An established method is used to find the stresses in a square plate pierced by a central circular hole. Although the method is not new, the problem is a practical one which has attracted some interest and for which some excellent experimental results are available.

The general problem of a finite plate containing a circular hole was examined by Sekiya who selected various combinations of the general solutions of the biharmonic equation in polar co-ordinates such that the boundary conditions on the hole were satisfied exactly. The boundary conditions on the sides of the plate were satisfied approximately by collocation. The same approach has recently been suggested by Waters for the particular case of a stress-free hole.
Similarity Relations for Vibrating Cylinder with Temperature Gradient across the Thickness
Authors: Modi V. J.
Published: July 2016

The dynamic analysis of heated structures is of considerable importance. Significant heating of a flight vehicle may take place at high speed causing reduction in its structural stiffness and vibration frequencies. Such changes in frequencies and mode shapes can substantially affect various static and dynamic aeroelastic instabilities.

In general, availability of a similarity law simplifies the solution of a problem. The following presentation studies similarity relations existing between an unheated vibrating cylinder and one with temperature gradient across its thickness.
Use of Longeron Anchored Cables in Multilobed Liquid Booster Tanks
Authors: Klein Bertram
Published: July 2016

The use of multilobed pressure vessels is not new. Such structures have been used in civil engineering applications for many years. It has been recognised that substantial weight savings are possible by reducing the radius of curvature by lobing. Usually the resulting discontinuity stresses at the junctions of the lobes have been balanced by attaching flat plates.
Drainage Criteria for Runway Surface Roughness
Authors: Moore Desmond F.
Published: July 2016

The main factor contributing to hydroplaning on slick runways is the existence of a squeeze film in the contact area between tyre and surface. The situation may be improved by optimising surface texture so that the asperities break through the water film in a minimum time. Two techniques are described for characterising surface texture: a superposition solution based on viscous channel flow and a dimensionless number approach involving size, spacing and shape factors. The “feel” of a surface is quantitatively obtained, and an outflow meter is described which, by directly measuring the mean hydraulic radius of runways, provides a comparison of their drainage abilities.
Aircraft Design Possibilities
Authors: Whitby R. H.
Published: July 2016

I hope that I shall be forgiven if I deal only in part with this subject, and also if I approach it from the airline engineer's point of view, although what I have to say is a personal expression of opinion.

Airlines are commercial undertakings and do not welcome change for change's sake. To improve service competitively from the point of view of time, regularity and safety and to encourage the continued growth of traffic through reductions in fares is the broad aim; it is against this background that, for example, the supersonic transport is being considered by the airlines. As you may have gathered, there is no marked enthusiasm. In due course, come it will, and traffic management plans must bear it in mind in considering future developments in Air Traffic Management. I am going to adopt the rather conservative attitude that most air traffic over the next two decades will be in aircraft much as we know them at present, and that if the growth in traffic leads to difficulties in Air Traffic Management then the main source of improvement must be sought in the system of management.
Balance of Helm and Static Directional Stability of Yachts Sailing Close-Hauled
Authors: Letcher John S.
Published: July 2016

An analysis is presented for equilibrium of yawing moments for a yacht sailing in the displacement mode in smooth water. The geometry of hull form and sail plan are quite unrestricted, although special attention is given throughout to currently popular types.

The free-surface flow is simplified by a reflection technique. In cases where the hull form is appropriate, the hull hydrodynamics are treated by lifting-line theory: in other cases slender-body theory is applied. The sail aerodynamics are treated by methods taken from aerofoil theory. Some design charts are given and computation methods are suggested for practical design calculations.

Static directional stability is treated theoretically and some general conclusions drawn regarding the influence of various characteristics on stability.

Where the theory has been applied, results have agreed with the available experimental data within the limits normally provided for adjusting balance of helm. Changes of balance with angle of heel and static stability have been given by the theory at least qualitatively correctly; experimental results are, however, not available for comparison.
Dissertation on “The Rank Technique” and its Application
Authors: Robinson John
Published: July 2016

“The Rank Technique” is a method for automatic selection of redundancies in the Matrix Force Method. The method was developed for the complete linear analysis of general plane frames, but is equally applicable to other forms of two- and three-dimensional configurations whose state can be expressed as a system of linear equations. An attractive feature of the method is that the structure is systematically and automatically investigated to determine its basic characteristics. The first point considered is whether the structure is stable or unstable for the prescribed load conditions; if stable, whether determinate or redundant and if redundant, the degree of redundancy. A consistent set of redundants is automatically isolated. For general structures the technique automatically generates the basic and redundant load systems in an indirect manner which can be made readily available, if required. The initial development of “The Rank Technique” was carried out in collaboration with Robert R. Regl and is given in reference 1.
The Influence of Attached Boundary Layers in Determining the Optimum Loading for Blades in Cascade
Authors: Stratford B. S.
Published: July 2016

In the design of cascade blading for compressors and turbines it is often assumed that the maximum efficiency will be attained at the maximum loading that just avoids separation and critical Mach number effects. In a turbine, the overall pressure gradient is favourable so that it should be possible to achieve very high loadings and yet avoid separation. The question then arises as to whether or not such high loadings would produce a high efficiency. The present note suggests that in fact there is an optimum loading, beyond which there would be no improvement in efficiency even though separation and critical Mach number effects were avoided.
Cylindrical Bending of Long, Flat, Rectangular Plates Under Linearly Distributed Pressure
Authors: Bruce Joan
Published: July 2016

The Method employed by Timoshenko for the cylindrical bending of uniformly loaded rectangular plates with various edge conditions, has been extended for the case of pressure linearly distributed across the width of the plate.
A Note on the Supersonic Panel Flutter of Oblique Clamped Plates
Authors: Kornecki A.
Published: July 2016

Summary and Introduction

Recently, the effect of sweepback on the boundaries of supersonic panel flutter was studied in Ref. (1), (2) and (3), all of them dealing with rectangular plates.

The present note considers the problem of panel flutter boundary of plates in the shape of a parallelogram with all edges clamped.

It is assumed that Ackeret's theory of linearised two-dimensional supersonic aerodynamic loading gives an adequate approximation to the air forces for high Mach numbers.

The criterion of instability is the coalescence of frequencies.

A four-mode solution was obtained by means of Galerkin's method using first two streamwise and spanwise deflection modes. The results are represented in the form of diagrams for different aspect ratios(a/b)and sweep angles(ϕ).
Multiple Simultaneous Imaging Schlieren System
Authors: Creeden J . E. , Sterling King J.
Published: July 2016

The need for simultaneous use of more than one type of camera to record Schlieren images of aerodynamic phenomena has led a recent investigator to employ a system in which an additional image was reflected from the Schlieren stop when it intercepted a deflected beam. This note describes an alternative arrangement capable of producing at least four images, although in its present form it is only designed to produce three.
Transonic Similarity Correlation of the Terminal Shock Jump on Aerofoils
Authors: Mabey D. G.
Published: July 2016

This note illustrates the correlation of the pressure distributions measured on three NACA 16-series aerofoils at subsonic and transonic speeds. The transonic similarity parameters proposed by Spreiter

are used for the subsonic, transonic and supersonic types of flow illustrated in Fig. 1.
The Hovertruck — 1
Authors: Bingham A. E.
Published: July 2016

The phrase “Air-Cushioned Vehicle” describes the complete range of vehicles which obtain some or all of their support from a free pressurised cushion of air contained between the vehicle and the ground.

Vickers’ interest in air cushion vehicles stems directly from the basic work carried out on the Hovercraft—one type of air cushion vehicle—by Mr. C. S. Cockerell and the initiative and encouragement displayed by the N.R.D.C. through its subsidiary Hovercraft Development Ltd.
The Hovertruck — 2
Authors: Evans E. W. B.
Published: July 2016

A Great deal of information is available today which cannot over-emphasise what is at the moment, the serious plight of millions of people in the world and which will become more serious unless agriculture and science can continually develop new techniques to increase production.

There is more than enough land in the world if only it can be developed and farmed. What is needed is capital, work and new ideas for its means, so that, if all are to be fed enough food, the grain production of the world must be doubled and the animal production tripled.
The Pilot's Viewpoint —2
Authors: Woolley D. H.
Published: July 2016

The Agricultural pilot looks for the following qualities in his aircraft, and I suggest that he looks for them in this order of importance:

Lively performance

Docile handling

Personal protection in an accident

Reliability of both aircraft and agricultural gear.

I said that performance should be lively. Perhaps it should be not far short of exhilarating. Certainly in many cases in current operations it can barely be described as adequate. Of course, some conditions of work call for a higher performance than others, and it is not possible to talk about ideal figures without relating them to a specific operation. Compromise is inevitable, but the most exacting types of work must be kept always in mind. Admittedly, most suggestions for performance minima made by a pilot may call for engines and power loadings which will seem quite uneconomical to the operator, particularly as engine overhaul costs often appear to increase as the square of the engine power.
Velocities Induced by The Vortex Wake of a Propeller in a Duct
Authors: Hickling Robert
Published: July 2016

If it is assumed that the effect of radial flow can be neglected, then the vortices which are shed from the trailing edge of a propeller blade can be said to lie approximately on helical lines. These vortices form a vortex sheet which for practical purposes is assumed to extend unaltered downstream to infinity. If the propeller blade is approximated by a lifting-line of bound vorticity, then the velocities at the blade induced by the trailing vortex system can be derived from the simple flow conditions in the hypothetical far wake where the vortex sheets extend equally to infinity in both directions. Results are already well-known for the case where the vortex sheets exist in free space. It is the purpose here to examine the effect of adjacent boundaries, such as the hub and the duct wall of a ducted propeller. The results also relate to a test propeller in a tunnel.
Efficiencies, Thermodynamics and the By-Pass Engine
Authors: Filleul N. le S.
Published: July 2016

All too often, points dealing with some aspect or other of the thermodynamics of powerplants are made which are incomplete, ambiguous, erroneous, or a mixture of all three! The purpose of this note is to try to give a limited, but logical, theoretical analysis of one type of propulsion powerplant, namely the by-pass engine with the possibility of heat exchange between the by-pass air stream and the main gas stream before expansion through the propulsion nozzles. This is a problem to which the solution is not obvious, and which would probably present difficulties to the average student. Heat exchangers are perhaps more of hypothetical rather than practical interest at present, but it is important that a correct thermodynamic approach be made in every case. Nothing is less likely to be engineered than a Carnot engine, and the general line of argument should be of wider appeal than the particular example to which it is applied.
Note on the Cylindrical Ejector Supersonic Propelling Nozzle
Authors: Ahren B.
Published: July 2016

In a technical note in the January 1963 Journal J. Dunham shows a method to determine the choked condition in a cylindrical ejector nozzle which in a simpler way leads to the same expression that has been derived by H. Pearson et al. of Rolls-Royce Ltd. Although Mr. Dunham states it is unnecessary to use the “maximum-discharge” principle, his derivation in the case of two streams in a common passage is, by the assumptions he makes, based on just this principle.
Design for Runway Conditions
Authors: Thomas J. W. H.
Published: July 2016

The designer's task is always to choose the best compromise to meet the various conflicting requirements put upon him. This task is eased when these requirements and ways of meeting them are expressed precisely in numbers, which is so in most performance work, but rarely true of safety or reliability.

In these latter areas the feedback of operational information shows when a problem exists and how important it is. For existing aircraft a solution must often be sought by ad hoc tests before the results of fundamental research are available.
Development of Guided, Tactical Missiles in France
Authors: Stauff Emile
Published: July 2016

Before I attempt to describe the various missiles which we have developed, I feel it useful to give a brief review of the evolution with time of our technical group, of the position of this group in France and finally of the criteria which guided its choice of a working programme.

Our technical team was formed in 1946 at the Arsenal de 1'Aéronautique, a government establishment. Its staff, at that time, comprised some ten engineers and specialists. In 1953, the Arsenal de 1'Aéronautique was turned into a company, the SFECMAS, which eventually merged with Nord-Aviation in 1955. The growth in manpower and facilities of the Nord missile group went on steadily during that entire period. The present staff amounts to some 900 engineers and specialists, who are employed only in laboratories, design, research and test facilities. This does not include the production side, which is dispersed among four plants outside the Paris Area.
Development of the Tilt-Wing Aircraft
Authors: Nichols John B.
Published: July 2016

The author accepted the invitation to present this paper on the rash assumption that he would be able to present something new and useful on the tilt-wing. The Hiller Company (in partnership with Vought and Ryan) was the first to have received a fully-fledged development contract for evaluation quantities of any VTOL machine. The VHR-447 which was selected as the Army, Navy and Air Force XC-142A was a culmination of almost ten years of effort spent in the investigation and promotion of the tilt-wing “propello-plane” VTOL aircraft concept.
Natural Vibration with Damping Force Proportional to a Power of the Velocity
Authors: Morley A. W. , Bryce W. D.
Published: July 2016

The friction force in many physical systems has been found to depend on a power of the velocity, the magnitude of which varies according to the damping mechanism. This note employs an approximate theory applicable to small damping to examine the free vibration of a single degree of freedom system in which the damping force is proportional to an unspecified power of the velocity.

Correlation with experimental data on the internal damping of solid materials shows that this phenomenon also tends to obey a power law although discrepancies exist between the expected and observed behaviours. These arise from the interpretation of the damping coefficient and from the frequency dependence of the dissipated energy.
A Note on the Lowest Natural Frequency of a Square Plate Point-Supported at the Corners
Authors: Kirk C. L.
Published: July 2016

Recently Cox and Boxer determined natural frequencies and mode shapes of flexural vibration of uniform rectangular isotropic plates, that have free edges and pinpoint supports at the four corners. In their analysis, they obtain approximate solutions of the differential equation through the use of finite difference expressions and an electronic digital computer. In the present note, the frequency expression and mode shape for a square plate, vibrating at the lowest natural frequency, are determined by considerations of energy. The values obtained are compared with those given in reference.
Packaged Liquid Rocket Motors
Authors: Neat W. N. , Page K. G.
Published: July 2016

The relative merits and possible applications of liquid and solid propellant rocket motors have long been topics for discussion and controversy. The arguments for and against have been sharpened by the fact that the development of the two types of motor are usually vested in quite different teams of people. At the same time, a fair comparison has often been confused because the ultimate choice has been made for reasons which are really not technical at all, but instead depend on availability and the utilisation of already deployed capital resources.

Nevertheless, the merits and de-merits of the “conventional” (as opposed to the packaged) liquid motor and the solid motor can be simply defined with reasonable accuracy. The liquid motor is complicated, demanding at least some, and often a great deal, of attention before use. At the same time, it has a much greater performance potential, can be used repeatedly and can be designed to give variable thrust. The solid motor is simpler (although is getting less so), is cheaper (although this is getting less true) and demands less preparation. However, it has definite performance limitations, is inflexible in its output, and is often quite sensitive to its environment, whether during storage, carriage, or operation.
The Response of a Typical Aircraft Structure to Jet Noise
Authors: Clarkson B. L. , Ford R. D.
Published: July 2016

The problem of the vibrations induced in an aircraft structure excited by jet noise has been solved mathematically in general terms by Powell and others. The most promising methods for dealing with a practical structure are those based on the normal mode approach. In these methods the response of the structure in each of its normal modes is first determined and then the total response is obtained by a summation of individual responses. Use of these methods on practical structures is tedious because of the large number of modes which must be considered and also the difficulty of calculating theoretically the normal modes of a practical stiffened structure.
The Royal Aeronautical Society The First Fifty Years
Authors: Laurence Pritchard J.
Published: July 2016

Brearey was a most energetic Honorary Secretary. His belief in the ultimate success of the cause which he had taken up in the fiftieth year of his life with such enthusiasm was practically demonstrated by the many aircraft models with which he experimented and the lectures he gave. As has already been noted, he was not content with encouraging an interest in Aerial Navigation by means of the Aeronautical Society, but he founded the Aeronautical Club, where the more enthusiastic members could meet on the third Tuesday in each month and discuss their ideas in private. It was owing to the meetings of this Club that public lectures were arranged and demonstration given at the Annual Meetings of the Society.
The Initiation of Projects
Authors: Blackwell B. D.
Published: July 2016

In providing the introductory speech to the section of this Symposium which deals with The Initiation of Projects, I have both the advantages and disadvantages of the opening batsman. My advantage is that I can set the scene in the manner which suits my purpose and this, I propose, quite unashamedly to do and beg the Chairman’s forgiveness if I overlap too much.

First I want to give you two quotations from recent presidential addresses to this Society and to the Institution of Mechanical Engineers. I found them both peculiarly relevant to the issues we are met to discuss.

First, the Duke of Edinburgh in his recent Centenary Address to the Royal Aeronautical Society said, “Yet we all believe that it is ridiculous for a country which is supposed to be well advanced in engineering technology, to admit it cannot cope with aeronautics—the most advanced technology of them all.“
The Management of Projects
Authors: Mungo B. B.
Published: July 2016

The paper outlines the existing procedures employed in the field of defence procurement and mentions some new ones which may be used in the near future. It will serve as a reminder of the way in which major aircraft and weapon and equipment projects are conducted and will lay the foundations for what is hoped will be a fruitful discussion.
The State of the Art in Management Studies Applicable to Aerospace Activities
Authors: Dollimore G. P.
Published: July 2016

Perhaps I should start as earlier speakers have done with a disclaimer to the effect that I am not putting my thoughts forward as those of an expert in all fields of management. I am perhaps fortunate in having been concerned with projects which lend themselves to experiments in the use of integrated management techniques, and also in the operation of a company which, because of its medium size—a thousand or so strong—and its type of business, is just large enough on one hand to justify a reasonably sophisticated approach to general management and, on the other, small enough for one to see the effects of changes in approach. It is on this basis that I shall make my comments.
Reinforced Plastics for Jet Lift Engines
Authors: Gresham H. E. , Hannah C. G.
Published: July 2016

Summary:—

Extensive use of reinforced plastics has contributed significantly to the success of small VTOL engines, notably the Rolls-Royce RB 162 series in whose compressors it has been possible to demonstrate their versatility and ruggedness. The choice of reinforced plastics for such obvious reasons as lightness, specific strength and corrosion resistance has been fully justified, while apparent deficiencies in stiffness and rain erosion resistance have not proved embarrassing.

Considerable use has been made of epoxy resin pre-impregnated sheet incorporating non-woven parallel aligned glass fibre, in particular the “Scotchply” series of “pre-pregs”. Exceptionally high fibre contents have been achieved, resulting in higher strengths and moduli than are usual with glass-reinforced plastics and furthermore, since Scotchply has proved so uniform in composition and ply thickness it has been possible to precision-mould most components with such accuracy that machining is eliminated—a major economic factor. Further economies have been achieved by minimising press curing times by the use of latent catalytic type hardeners for the resin systems which, in addition, confer long storage life and good heat resistance. The use of very thin sheet material has allowed much ply orientation within laminates, resulting in substantial and controllable variations in anisotropy, allowing properties to be tailored more nearly to meet the conditions imposed.
New Notation for Aircraft Dynamics
Authors: Melling R.
Published: July 2016

Notations and nomenclature for aircraft dynamics and associated aerodynamic data have evolved over many years. Common usage broadly followed the ideas laid down by Bryan, Glauert, Bryant and Gates, and extensions eventually resulted in a conglomeration of symbols which generally impeded the efforts of students, teachers, and other workers and there was little scope for making further additions in a sensible way.

Much work has been done at the Royal Aircraft Establishment to rationalise the position, and the resulting scheme is presented in RAE Technical Report TR 66200. In this scheme changes are kept to the minimum possible, existing concepts are retained, and considerable care is taken to provide a flexible system which allows an author a great deal of freedom as regards simplifying the notation in particular investigations—by omitting suffixes, for example. The RAE is confident that the new notation and nomenclature will overcome the inadequacies of existing systems.
The Derivation of a Formula for Thrust from Thermodynamic Energy Equations
Authors: Buchan A. L.
Published: July 2016

It is usual to consider equilibrium between the forces and accelerations associated with individual fluid elements when deriving thrust formulae containing momentum terms. Thermodynamic energy equations for open systems, however, only rely on the premise that, as far as energy is concerned, what goes into a system must either come out or else build up inside.

In thermodynamic textbooks a distinction is usually drawn between steady flow, involving no change of energy with time inside a system, and non-steady flow, which implies a rate of change of energy within the thermodynamic system under consideration.

It is interesting to find that the thrust formula for a simple system, as shown in Fig. 1, may be derived directly from these thermodynamic energy equations by two alternative methods.
A Method of Measuring the Concentration of Certain Polymers in Dilute Aqueous Solutions
Authors: Goren Y. , Kane P. O. , Norbury J. F.
Published: July 2016

A technique has been devised for measuring the concentration of “Polyox” in dilute aqueous solutions. “Poly-ox”* is one of those polymers whose addition to water in low concentrations causes a reduction in skin friction (if the Reynolds number is sufficiently high) in turbulent flow through a pipe or boundary layer. (See, for example, ref. 1.) The analytical method is probably applicable to other polymers having this property, and it should be generally useful in this field of research. For example, in any experiment in which a polymer solution is injected at a point in a boundary layer, the method could be used to determine the distribution of polymer concentration at downstream sections. It is based on polarography, a well-established tool of chemical analysis of which an excellent account is given in ref. 2.
The Royal Aeronautical Society The First Fifty Years—1866 and All That
Authors: Laurence Pritchard J.
Published: July 2016

“ God bless the Duke of Argyll!”

In the Lecture Hall at Hamilton Place, London, of the oldest aeronautical society in the world, that Duke of Argyll, who became its first President in 1866, looks silently down upon those members who, less than a century later, succeeded so noisily to fly faster than the sounds of their own triumphant cries of success.
The Distribution of Shear Stresses in an I Section Beam
Authors: Wood W. G.
Published: July 2016

When a Beam is subjected to a static transverse load acting through its flexural centre, the resulting deflection may be considered as the combined effect of the deflection due to bending stresses and the deflection due to shear stresses. In a majority of cases, where the span of the beam is large, or where the shear stiffness is large compared with the bending stiffness, the bending component only need be considered. However, for a short beam, the shear deflection can account for a substantial part of the total deflection. This is especially so in the case of a deep I section beam with a thin web, where the bending stiffness is large compared with the shear stiffness.
The Antiquity of the Royal Aircraft Establishment
Authors: Walker P. B.
Published: July 2016

Apart from Royal patronage and the manifest concern with aviation, it must seem to many people that there is little in common between the Royal Aeronautical Society and the Royal Aircraft Establishment. Yet research into the lesser known activities of the early RAE has revealed not only a comparable antiquity but also a remarkable similarity in the early history of the two bodies. Both had to fight hard to stay alive, and often continuing existence depended upon a tenuous thread liable to snap at any moment.

In its early years the Society was essentially a group of dilettante with all the advantages as well as the disadvantages that this entails.
Aircraft Structures
Authors: Howard H. B. , Chitty L. , Watts H. C.
Published: July 2016

It was with some trepidation that I accepted the Society's invitation to contribute a Chapter to this Centenary issue. As the Lord Chancellor in Iolanthe has it,

“But though the compliment impliedInflates me with legitimate pride,It nevertheless can't be deniedThat it has its inconvenient side.“

Nearly all those mentioned in the following chronicle of British achievements have known me personally; many have been my colleagues. It would be unfortunate if what I have said, or have failed to say, about their work were to disturb hitherto harmonious relations.
With Frewen Jenkin at the Ministry
Authors: Aitchison Leslie
Published: July 2016

It was wise of Duff Cooper to remind us that “old men forget”, and I fully agree with him. But, like so many others, I find myself remembering more about the events of fifty years ago than I do about those of yesterday.

My entry into the world of aeronautics was brought about by R. V. Southwell (now Sir Richard), who asked if I would take a metallurgical post in the RNVR at Kingsnorth. I was, however, placed in the Materials Section of the Technical Department of the RNAS.

The head of the Materials Section was Commander Charles Frewen Jenkin.
British Aircraft Design
Authors: Macmillan Norman
Published: July 2016

Between 1910 and 1966 British aircraft design fell into certain distinct periods, each of which, more or less irrespective of the number and arrangement of the power units, may be recognised by its common structural pattern. In each period, as might be expected, there were exceptions to the contemporary common pattern, often only experimental, or built in srrall numbers.

In the first period, which lasted until about 1924, wirebraced wood airframe structures were the common pattern.
Early Days
Authors: Bulman Major G. P.
Published: July 2016

When one is young a century seems almost an aeon, mythical in its earlier days, peopled with men whose names are forgotten, or remembered only as seen on mouldering tomb stones in village churchyards. But to me, although only in the earlier seventies, the hundred years spanned by the Aeronautical Society of Great Britain (as it was originally called) is little more than “an evening gone”.

P. Y. Alexander, an engine enthusiast, was one of its early members, and a close friend of an uncle of mine, and I met him in his later years.
Aircraft Accessories
Authors: Stevens James Hay
Published: July 2016

If one looks back over the half century, or there abouts, of practical aviation, the enormous changes in aircraft and powerplants have been accompanied by an equal metamorphosis in their accessories. As soon as aeroplanes progressed beyond the stage of short hops from skids, the accessories began to develop: in the cockpit, the air speed indicator, the altimeter and the bubble levels; in the structure, the undercarriage and its shock absorbers.
Design Requirements for Military Aircraft
Authors: Day A.
Published: July 2016

This paper traces the development and administration of design requirements for military aircraft over the past 50 years. The period has been divided into three eras, the era leading up to the first issue of the universally known design handbook AP 970, the between-wars era, and finally the last 25 years which has been called the Joint Airworthiness Committee (JAC) era.
Blazing the Trail
Authors: Cobham Alan
Published: July 2016

At the end of the First World War, from a design point of view, aviation seemed to slow down compared with the tempo of progress during the war years. From the practical flying angle, there were brave efforts by a few to create flying records, such as the first crossing of the North Atlantic by air. Hawker and Grieve took off from Newfoundland and accomplished a remarkable feat of landing in mid-Atlantic and being picked up by a steamer. Alcock and Brown, in a war-time Vickers Vimy made a successful crossing, but unfortunately ended up in a bog in Northern Ireland.
IT'S NOT JUST THE TECHNOLOGY, IT'S THE SURROUNDING SYSTEM: HOW RESEARCHERS IN ECUADOR FOUND WAYS TO MAKE THEMSELVES USEFUL TO FARMERS THROUGH QUINOA AND LUPIN SEED SYSTEMS
Authors: MAZÓN NELSON , PERALTA EDUARDO , MURILLO ÁNGEL , RIVERA MARCO , GUZMÁN ALFONSO , PICHAZACA NICOLÁS , NICKLIN CLAIRE
Published: July 2016

Agriculture research often focuses on a technical problem. However, the most effective researchers usually intuit that this entry point is not sufficient to make themselves useful to farmers and nudge systems. Yet non-technical work frequently goes undocumented leaving many of the drivers of success unstudied. This paper attempts to understand the factors that contributed to the wide utilization of native crop varieties and species that were being promoted by the Ecuadorian National Agriculture Research Institution. The results show that what really made a difference in farmers' lives and the overall food system was increasing farmers' knowledge and capacity to produce quality seeds, promoting the consumption of these crops to national consumers, and linking farmers to outside groups. As a result, over a period of five years three case studies on three different farmer groups showed adoption rates of new varieties of between 20–50% and that they were able to produce approximately 7.5% of the annual demand for quinoa and lupin seed in Ecuador, from a starting point of virtually nothing. The research shows that the added value of a research institution might not be known at the beginning of the intervention, but rather will emerge over time through dialogue and negotiation based on systematic understanding of the context. Therefore, an appropriate stance for external organizations is to begin with an awareness of the existing assets of a specific farmer group and provide options that can be leveraged by local communities.
A Transposition Rule Analysis Based on a Particle Process
Authors: Gamarnik David , Momčilović Petar
Published: July 2016

A linear list is a collection of items that can be accessed sequentially. The cost of a request is the number of items that need to be examined before the desired item is located, i.e. the distance of the requested item from the beginning of the list. The transposition rule is one of the algorithms designed to reduce the search cost by organizing the list. In particular, upon a request for a given item, the item is transposed with the preceding one. We develop a new approach for analyzing the algorithm, based on a coupling to a certain constrained asymmetric exclusion process. This allows us to establish an asymptotic optimality of the rule for two families of request distributions.
The Large Deviations of Estimating Rate Functions
Authors: Duffy Ken , Metcalfe Anthony P.
Published: July 2016

Given a sequence of bounded random variables that satisfies a well-known mixing condition, it is shown that empirical estimates of the rate function for the partial sums process satisfy the large deviation principle in the space of convex functions equipped with the Attouch-Wets topology. As an application, a large deviation principle for estimating the exponent in the tail of the queue length distribution at a single-server queue with infinite waiting space is proved.
Heterogeneous population dynamical model: a filtering problem
Authors: Gerardi A. , Tardelli P.
Published: July 2016

We consider a heterogeneous population of identical particles divided into a finite number of classes according to their level of health. The partition can change over time, and a suitable exchangeability assumption is made to allow for having identical items of different types. The partition is not observed; we only observe the cardinality of a particular class. We discuss the problem of finding the conditional distribution of particle lifetimes, given such observations, using stochastic filtering techniques. In particular, a discrete-time approximation is given.
Fluid limit of generalized Jackson queueing networks with stationary and ergodic arrivals and service times
Authors: Lelarge Marc
Published: July 2016

We use a sample-path technique to derive asymptotics of generalized Jackson queueing networks in the fluid scale; that is, when space and time are scaled by the same factor n. The analysis only presupposes the existence of long-run averages and is based on some monotonicity and concavity arguments for the fluid processes. The results provide a functional strong law of large numbers for stochastic Jackson queueing networks, since they apply to their sample paths with probability 1. The fluid processes are shown to be piecewise linear and an explicit formulation of the different drifts is computed. A few applications of this fluid limit are given. In particular, a new computation of the constant that appears in the stability condition for such networks is given. In a certain context of a rare event, the fluid limit of the network is also derived explicitly.
Berry-Esseen bounds for combinatorial central limit theorems and pattern occurrences, using zero and size biasing
Authors: Goldstein Larry
Published: July 2016

Berry-Esseen-type bounds to the normal, based on zero- and size-bias couplings, are derived using Stein's method. The zero biasing bounds are illustrated in an application to combinatorial central limit theorems in which the random permutation has either the uniform distribution or one that is constant over permutations with the same cycle type, with no fixed points. The size biasing bounds are applied to the occurrences of fixed, relatively ordered subsequences (such as rising sequences) in a random permutation, and to the occurrences of patterns, extreme values, and subgraphs in finite graphs.
The moment problem for some Wiener functionals: corrections to previous proofs (with an appendix by H. L. Pedersen)
Authors: Hörfelt Per
Published: July 2016

In this paper, we describe a class of Wiener functionals that are ‘indeterminate by their moments’, that is, whose distributions are not uniquely determined by their moments. In particular, it is proved that the integral of a geometric Brownian motion is indeterminate by its moments and, moreover, shown that previous proofs of this result are incorrect. The main result of this paper is based on geometric inequalities in Gauss space and on a generalization of the Krein criterion due to H. L. Pedersen.
Nonstationary value iteration in controlled Markov chains with risk-sensitive average criterion
Authors: Cavazos-Cadena Rolando , Montes-De-Oca Raúl
Published: July 2016

This work concerns Markov decision chains with finite state spaces and compact action sets. The performance index is the long-run risk-sensitive average cost criterion, and it is assumed that, under each stationary policy, the state space is a communicating class and that the cost function and the transition law depend continuously on the action. These latter data are not directly available to the decision-maker, but convergent approximations are known or are more easily computed. In this context, the nonstationary value iteration algorithm is used to approximate the solution of the optimality equation, and to obtain a nearly optimal stationary policy.
On the geometric growth in a class of homogeneous multitype Markov chain
Authors: González M. , Martínez R. , Mota M.
Published: July 2016

In this paper, we investigate the geometric growth of homogeneous multitype Markov chains whose states have nonnegative integer coordinates. Such models are considered in a situation similar to the supercritical case for branching processes. Finally, our general theoretical results are applied to a class of controlled multitype branching process in which the control is random.
A central limit property under a modified Ehrenfest urn design
Authors: Chen Yung-Pin
Published: July 2016

We consider a stochastic process in a modified Ehrenfest urn model. The modification prescribes there to be a minimum number of balls in each urn, and the process records the differences between treatment assignments under a sampling scheme implemented with this modified Ehrenfest urn model. In contrast to the result that the difference process forms a Markov chain and converges to a stationary distribution under the Ehrenfest urn model, the corresponding process under this modified Ehrenfest urn design satisfies the central limit property. We prove this asymptotic normality property using a central limit theorem for dependent random variables, renewal theory, and two Kolmogorov-type maximal inequalities.
Moments of a Markov-modulated, irreducible network of fluid queues
Authors: Rabehasaina Landy
Published: July 2016

We study a network of fluid queues in which exogenous arrivals are modulated by a continuous-time Markov chain. Service rates in each queue are proportional to the queue size, and the network is assumed to be irreducible. The queue levels satisfy a linear, vector-valued differential equation. We obtain joint moments of the queue sizes recursively, and deduce the Laplace transform of the queue sizes in the stationary regime.
Derivatives pricing via p-optimal martingale measures: some extreme cases
Authors: Santacroce Marina
Published: July 2016

In an incomplete financial market in which the dynamics of the asset prices is driven by ad-dimensional continuous semimartingaleX, we consider the problem of pricing European contingent claims embedded in a power utility framework. This problem reduces to identifying thep-optimal martingale measure, which can be given in terms of the solution to a semimartingale backward equation. We use this characterization to examine two extreme cases. In particular, we find a necessary and sufficient condition, written in terms of the mean-variance trade-off, for thep-optimal martingale measure to coincide with the minimal martingale measure. Moreover, if and only if an exponential function of the mean-variance trade-off is a martingale strongly orthogonal to the asset price process, thep-optimal martingale measure can be simply expressed in terms of a Doléans-Dade exponential involvingX.
A matrix-analytic approach to the N-player ruin problem
Authors: Swan Yvik C. , Bruss F. Thomas
Published: July 2016

ConsiderNplayers, respectively owningx1,x2, …,xNmonetary units, who play a sequence of games, winning from and losing to each other integer amounts according to fixed rules. The sequence stops as soon as (at least) one player is ruined. We are interested in the ruin process of theseNplayers, i.e. in the probability that a given player is ruined first, and also in the expected ruin time. This problem is called theN-player ruin problem. In this paper, the problem is set up as a multivariate absorbing Markov chain with an absorbing state corresponding to the ruin of each player. This is then discussed in the context of phase-type distributions where each phase is represented by a vector of sizeNand the distribution has as many absorbing points as there are ruin events. We use this modified phase-type distribution to obtain an explicit solution to theN-player problem. We define a partition of the set of transient states into different levels, and on it give an extension of the folding algorithm (see Ye and Li (1994)). This provides an efficient computational procedure for calculating some of the key measures.
Maximal avalanches in the Bak-Sneppen model
Authors: Gillett Alexis , Meester Ronald , van der Wal Peter
Published: July 2016

We study the durations of the avalanches in the maximal avalanche decomposition of the Bak-Sneppen evolution model. We show that all the avalanches in this maximal decomposition have infinite expectation, but only ‘barely’, in the sense that if we made the appropriate threshold a tiny amount smaller (in a certain sense), then the avalanches would have finite expectation. The first of these results is somewhat surprising, since simulations suggest finite expectations.
Discretionary stopping of one-dimensional Itô diffusions with a staircase reward function
Authors: Bronstein Anne Laure , Hughston Lane P. , Pistorius Martijn R. , Zervos Mihail
Published: July 2016

We consider the problem of optimally stopping a general one-dimensional Itô diffusion X. In particular, we solve the problem that aims at maximising the performance criterion E
x
[exp(-∫0
τ
r(X

s
)ds)f(X
τ)] over all stopping times τ, where the reward function f can take only a finite number of values and has a ‘staircase’ form. This problem is partly motivated by applications to financial asset pricing. Our results are of an explicit analytic nature and completely characterise the optimal stopping time. Also, it turns out that the problem's value function is not C
1, which is due to the fact that the reward function f is not continuous.
Characterizations in a random record model with a nonidentically distributed initial record
Authors: Barlevy Gadi , Nagaraja H. N.
Published: July 2016

We consider a sequence, of random length M, of independent, continuous observations X

i
, 1 ≤ i ≤ M, where M is geometric, X
1 has cumulative distribution function (CDF) G, and X

i
, i ≥ 2, have CDF F. Let N be the number of upper records and let R

n
, n ≥ 1, be the nth record value. We show that N is independent of F if and only if G(x) = G
0(F(x)) for some CDF G
0, and that if E(|X
2|) is finite then so is E(|R

n
|), n ≥ 2, whenever N ≥ n or N = n. We prove that the distribution of N, along with appropriately chosen subsequences of E(R

n
), characterize F and G and, along with subsequences of E(R

n
- R

n-1), characterize F and G up to a common location shift. We discuss some applications to the identification of the wage offer distribution in job search models.