bluuebunny/crossref_metadata_2025 huggingface dataset:
Part III: On an incremental problem related to the steady flow about an aerofoil/spoiler configuration
Authors: Tou H. B. , Hancock G. J.
Published: July 2016

In Part II*, an inviscid model using a panel method has been formulated to solve separated flow past a steady aerofoil/spoiler configuration in a low speed stream. In this note, an investigation has been carried out to formulate an incremental model to solve the steady incremental problem when the aerofoil/spoiler changes its geometry by a small mount (eg for a small angular change of the spoiler).

It has been found that to satisfy the incremental boundary conditions on the initial aerofoil/spoiler geometry, incremental changes in the influence coefficients have to be included for the small change in aerofoil/spoiler geometry and the change in separation streamline geometry. A first order procedure is satisfactory; a second order procedure is also presented.
Real actuator effects and the aerodynamic energy method
Authors: Simpson A.
Published: July 2016

The aerodynamic energy method provides a means of flutter-suppression control-law design based wholly on oscillatory aerodynamic forces on a notional structure with notional normal vibration modes. The method has been proposed as a means of flutter suppression regardless of structural considerations, other than those mentioned. As originally conceived, the method is based upon the assumption of totally irreversible active controls. In this paper, the effects of finite impedance of actuators on the implementation of the method are investigated analytically. The conclusions do not augur well for the method.
Wing tip sails; progress to date and future developments
Authors: Spillman J. J.
Published: July 2016

Studies begun over ten years ago have shown that the swirling air flow about the tips of a lifting wing can be redirected using small aerofoil surfaces, called sails, to reduce the overall lift-dependent drag of the wing. Tests on Paris, Jetstream and other windtunnel models, confirmed by flight tests on Paris and Centurion aircraft have shown marked reductions in drag and fuel consumption. Handling tests show improvements in roll control and stalling speeds.

Wing tip sails have the effect of reducing the peak adverse effects on other aircraft flying through the wake of a Paris aircraft but reduce the decay rate so the far field effects are worsened. Sails fitted to a crop-spraying aircraft have significantly reduced the amount of spray lifted above the height of the aircraft by the tip vortices and subsequently blown off-target by a cross-wind.

Windtunnel tests on a model with variable incidence sails show that differential sail incidence can be used effectively to provide roll power, reducing the size of the ailerons required, so allowing a greater flap span. The maximum root bending moments of the wings can be reduced by at least 10% by using negative sail movements in positive manoeuvres or gusts.

Sails can reduce the drag of an aircraft at all speeds leading to fuel savings estimated at US$225 per annum per 1000lb take-off weight per 1000 hours annual utilisation. For an airliner of 300 000lb weight and operating for 3000 hours this means a fuel saving of over a fifth of a million dollars per year!
Part V: Steady and oscillatory aerofoil-spoiler-flap characteristics
Authors: Tou H. B. , Hancock G. J.
Published: July 2016

An inviscid model for a steady two-dimensional aerofoil-spoiler at low speeds is applied to an aerofoil-spoiler-plain flap configuration. The model is extended to an aerofoil-spoiler-slotted flap configuration. The flow through a slotted flap can result in either attached flow or separated flow about the flap. The location of the separation point on the flap has to be assumed, it is taken empirically to fit experimental data. The inviscid model is extended to the aerofoil-spoiler-slotted flap configuration with the spoiler oscillating in small amplitude simple harmonic motion about a mean spoiler angle. Although both the steady and unsteady models for the aerofoil-spoiler-flap configuration are crude, the results look encouraging.
Three-Dimensional Free Jets
Authors: Rajaratnam N. , Subramanya K.
Published: July 2016

Fairly elegant semi-empirical theories are available for predicting the turbulent diffusion of axisymmetric and plane jets. However, there are relatively few investigations on the non-axisymmetric jets, herein denoted as three-dimensional jets. The extensive investigations conducted at the Polytechnic Institute of Brooklyn on three-dimensional jets have shown that the flow field is characterised by three distinct regions; the potential core, the characteristic decay (CD) region and the axisymmetric decay (AD) region. In the CD region the velocity profiles in the direction of the minor axis are similar but the maximum velocity decay curves are different for different shapes. In the AD region the flow characteristics are similar to that of an axisymmetric jet. Yevdjevich has recently conducted another investigation on rectangular jets.
On the Use of the Preston Tube in Concentric Annuli
Authors: Lyall H. G.
Published: July 2016

In his technical note in the January 1967 JOURNAL, Quarmby (pp 47-49) concludes that because he was able to predict the axial pressure gradient in a concentric smooth annulus by using Preston tubes to measure the inner and outer wall shear stress, then the Preston tubes are giving correct values for the wall shear stresses. I cannot agree that this is a valid conclusion to draw. A Preston tube can only give wall shear stress correctly if the dimensionless velocity in the wall region is the same as that for which the tube was calibrated.
On the Use of the Preston Tube in Concentric Annuli
Authors: Quarmby Alan
Published: July 2016

Mr. Lyall's remarks may be answered from the evidence already present in refs 1 and 2 if these are considered objectively. They establish that the ratio of the shear stresses as given by Preston tubes is correct. Evidence on this point is given by the value obtained for rmt from the Preston tube measurement of shear stress ratio and its agreement with the correlation of rmt as a function of radius ratio given by Leung, Kays and Reynolds.
The View of a Constructor's Pilot
Authors: Baker P. P.
Published: July 2016

This subject, even as it applies to those areas which are the direct or partial responsibility of the test pilot, is a comprehensive one, and it is not intended to embrace it completely. Specifically this paper will touch only on the area in which the pilot is principally involved. Further, it is not the intention to catalogue the tests required for certification or to describe all of them in detail, but rather to discuss the whole certification process in more general terms.

The purpose of Certification is to establish a minimum safety standard, but when forming that standard, sight cannot be lost of the feasibility of achieving it, both practically and commercially. Inevitably, therefore, the discussions or arguments that arise over establishing the standards against which aircraft are going to be assessed must centre around the problem of where the balance between safety and cost should be struck. As previously implied, absolute safety is not only probably impossible to achieve, but quite clearly commercially impractical. The constructor's task must be, therefore, a process of resolving the often conflicting ideas of the various bodies and agencies that attempt to define the “balance” and within that definition offer a commercially attractive aircraft. If he strays widely from the prevailing definition, even in the interests of increased safety, he is in danger of pricing himself out of business. This fact is rather obvious, but no excuse is given for stating it since it is thought to be so fundamental to the subject under discussion, and one that is often overlooked, particularly perhaps by those who are not so involved with the day-to-day operation of aircraft.
Engine Performance Monitoring—Application to Small Fleets and Short-Haul Operation
Authors: Hope J. , Kenworthy K.
Published: July 2016

Although the title of this paper, for brevity, refers to engine performance monitoring, in fact we mean performance and condition monitoring. In presenting such a paper with particular emphasis on the problems that arise for the Operator with relatively small aircraft fleets operating in the main over short stages, although the comments we have to make are based on TAA experience, a similar situation must exist for any operator with a multiplicity of aircraft types and relatively small numbers of each.

We refer to performance and condition monitoring to define the complete task, as it is essential to correlate performance parameters to condition evidence such as vibration level or lubricant deterioration status to obtain a useful perspective.
Self-Aligning Hot-Wire Probe
Authors: Bond A. D. , Porter A. M.
Published: July 2016

Summary:—

This note describes how a single constant temperature hot wire may be used for measurements of direction, velocity and turbulence in a two-dimensional flow. The wire probe is rotated by a servo motor which automatically sets the wire with its axis either in the stream direction or normal to the flow. The accuracy of setting the wire in the direction of the stream is about , and across the stream is about 1°. If the higher accuracy is demanded the velocity and turbulence measurements require a second setting of the probe, at 90° to the previous one. When less precision is acceptable, the angle, velocity and turbulence measurements may be taken at the single setting, normal to the stream.
The Application of Lifting Line Theory to an Upright Bermudan Mainsail
Authors: Tanner T.
Published: July 2016

Using Glauert's analysis and taking into account the restraint due to the surface of the sea, lifting line theory is applied to calculate the distribution of loading, downwash velocity and vortex drag of a “Finn” dinghy's sail when upright. It appears that the loading can probably be represented with sufficient accuracy by

I=I0(sin θ+sin 2θ)

where k is largely dependent on the apparent twist in the sail and has a value generally of the order of 0-5, that the apparent twist may not be twist at all in the aerodynamic sense, and that the vortex drag is considerably greater than it would be if it were possible to make a sail to give elliptic loading.
On the Definition of “Cooling Losses” in Cooled Gas Turbines
Authors: Ogale V. A. , Jaspers B. W.
Published: July 2016

In the analysis of cooled gas turbine cycles, the quantity of heat removed by the coolant is termed as “cooling loss”. In the literature, these cooling losses are accounted for by the use of either

(a) Cooling Loss Factor, or

(b) Cooling Number.

Brown defines Cooling Loss Factor (CLF) as a ratio of heat removed by coolant per unit time divided by the total turbine output per unit time.

Traupel defines the Cooling Number (CN) as the ratio of heat loss to isentropic enthalpy drop.

Cohen and Martin use the CLF in their analyses and May uses the CN.

It is the purpose of this note to give a simple correlation of the two and to suggest a new definition to account for these losses.
An Iterative Technique for Minimising a Double Integral with Applications in Elasticity
Authors: Webber J. P. H.
Published: July 2016

The solution of a problem in plane elasticity can be associated with a minimum energy principle, involving the minimisation of a double integral subject to certain boundary conditions. In 1933, Kantorovich proposed a method which reduced this problem to that of finding the minimum of a single integral. He chose part of the solution a priori (in accordance with the character of the problem) which left only one undetermined function in one of the variables. This unknown function could then be found through the solution to an ordinary differential equation. He then constructed a second approximation by introducing two unknown functions which led to the solution of two simultaneous differential equations. Again the accuracy of the solution was dependent on the initial choice for part of the function; so also was the rate of convergence.
Compounded Normal Modes of Free Vibration of Cantilever Plates
Authors: Kirk C. L.
Published: July 2016

In the vibration of isotropic rectangular plates, the phenomenon of the simultaneous excitation of two separate modes having equal frequencies is well known. Wallerobserved complex nodal patterns on isotropic rectangular plates, and she stated that such combinations were possible because of the internal damping of the plates, which reduced the sharpness of resonance.

Warburton considered the existence of modesm/n±n/mfor a clamped plate and showed that when a plate is square, for the mode 4/2 + 2/4, the nodal lines do not lie parallel to the edges of the plate. Furthermore, it was proved that for a square clamped plate, the modesm/n±n/mhave discrete frequencies.
National Aerospace Planning
Authors: Caplan H.
Published: July 2016

Summary:—There is no doubt of the need for strong central planning of aeronautical research and development as advocated by the Post-Plowden Working Party of the Royal Aeronautical Society (pp. 391-392 June 1967 “Journal“).

But there are many other problems in the efficient use of aerospace resources which are equally in need of attention by the Society. Among the most important are:

The complementary role of improved industrial and project management.

The need to deal separately with the distinct problems of Defence, Civil Aviation and Space—in particular the improvement of Defence procurement methods.

The need to discover the correct commercial and engineering bases (as distinct from political bases) for European collaboration.

The need to complement the work of a strong planning organisation by providing facilities for high-level and informed technical debate, wherever possible in public.
Engine Development and Manufacture in Sweden
Authors: Gudmundson Gustaf
Published: July 2016

From the very start of aviation a suitable engine has been the basic pre-requisite for successful flight.

The first known Swedish proposal for a heavier-than-air flying machine was made in 1716 by the scientist and philosopher Emanuel Swedenborg. A steam engine, invented by him in 1714, was to provide the propulsion. His superior, “Royal Mechanicus” Christoffer Polhem, opposed the idea, and the project was abandoned without any attempt being made. More than 150 years later, in 1877, another Swede—Carl Rickard Nyberg, well-known inventor of the blow-lamp and other gas-producing devices using liquid fuel—presented a design for a helicopter and 20 years later still, for a steam-engine-driven aeroplane. The engine weight problem was to be solved by using a light tubular steam boiler, invented by him. Several prototypes were produced during the years 1899 to 1910 without being really flyable since the steam engine gave only 10 hp compared with the estimated 40 hp required.
Application of Film Cooling Theory to the Cooling of Aircraft Gas Turbine Chambers
Authors: Sturgess G. J.
Published: July 2016

Film cooling performance expressed in the terms of film effectiveness, is divided into initial and final regions containing respectively, the potential core and transition lengths and, the main decay region. The theory of Kutateladze and Leont'ev, which is representative of present approaches, is presented and shown not to apply to the film initial region. To resolve the questions, what is the minimum acceptable value of effectiveness in a given situation, and, what proportion of the resulting maximum permissible cooled distance is initial region, the film cooling of a hypothetical turbojet engine to power a Mach 2-2 cruise supersonic air liner is examined. Experimental data from cooling devices representative of current European practice are used in the analysis to give realistic results.
The Use of a Digital Computer for On-Line Control of a Jet Engine
Authors: Eccles E. S.
Published: July 2016

Some of the unusual factors influencing the choice of digital computer control systems for jet engines are discussed first. The conditions differ in various practical respects from conventional process control applications. Having several identical plants in a typical aircraft and the need for flexibility to keep pace with engine development are of particular importance. Approaching digital control with the traditional process control background may be restrictive in selecting potential applications for the technique.

Techniques which can be used with computers to simplify and speed up three aspects of the realisation of a practical system are described briefly. The first of these is the measurement of the actual plant characteristics needed in the analysis of the control system requirements. The second is a method of obtaining good response in the synthesis of a non-linear control function. The third is a technique for programme writing and for simulation used in the verification of the control system behaviour.

The techniques described are not in themselves necessarily confined to use with digital control systems and should have value in general use.
Centre-Body Nozzles for Supersonic Transport Aircraft
Authors: Herbert M. V.
Published: July 2016

In a supersonic transport aircraft, the propelling nozzle is required to operate at high efficiency over a wide range of conditions — typically a five to ten-fold variation of exhaust pressure ratio. This paper offers some discussion around the problems of geometry which such requirements entail, and explains the reasons for which a nozzle of centre-body form with parallel outer shroud appears an attractive solution. In support of the claims for this arrangement of nozzle, test data are presented from both single and twin models under representative conditions of external flow. (The tests were made at the National Gas Turbine Establishment between 1960 and 1965.)
Torsional Stress Concentration Factors for Grooved Shafts
Authors: Rushton K. R.
Published: July 2016

This paper describes a preliminary investigation of the torsional stress concentration factors for circular shafts containing grooves determined using an analogue computer. The range covered by this analysis is for grooves which increase in depth from a minimum of 0·05 of the diameter of the shaft, with radii which vary from 0·5 to 0·05 of the diameter at the minimum section. Results are presented in the form of a data sheet, and a comparison is made with the approximate expression of Neuber. An investigation is also made of the modifications to the stress concentration factor if the flank is not perpendicular to the centre-line of the shaft.
A Note on the “Isentropic Ramp” Intake Diffuser in the Mach Number Range 6 to 10
Authors: Bergstrom E. R.
Published: July 2016

A need exists for empirical criteria by which the behaviour of hypersonic boundary layers flowing in adverse pressure gradients can be predicted, thereby placing the design of high Mach number intake/diffuser systems on a rational basis.

The main results of the inviscid flow performance analysis of a two-dimensional “isentropic ramp” intake diffusing to supersonic Mach numbers over the free stream Mach number range 6 to 10 are presented. Limitations on the degree of diffusion, and hence geometry, have been deduced in terms of the combustion length requirements of an idealised hydrogen/air combustion process with com-bustor inlet conditions given by the intake. The analysis can be considered as a first order approximation defining the ranges of continuous pressure gradients and oblique shock wave strengths relevant to the experimental investigation of boundary layer flow in the mixed adverse pressure gradients associated with hypersonic intakes.
The Static Hole Pair as a Skin Friction Meter
Authors: Duffy J. , Norbury J. F.
Published: July 2016

In a recent technical note Rajaratnam has pointed out the possibility of using the pressure difference measured between two static pressure holes of different diameter as a means of determining skin friction. The device exploits the fact that for any hole there is an error in measurement of static pressure which depends both on the hole diameter and on local skin friction, as Shaw has demonstrated. Consequently the difference in pressure measured between two adjacent holes of different diameter will be a function of the skin friction. In this note the device will be called a “static hole pair”. The larger hole will be referred to as the “test” hole, and the smaller hole as the “reference” hole.
Recent Developments in Titanium
Authors: Shaw H. W.
Published: July 2016

The intention in presenting this paper is to outline the main trends in recent alloy development and to indicate the current state of the art as far as the user is concerned, particularly on the behaviour of the new products in the problem areas so designated by the engineering metallurgists and materials specialists in the industry.

In reviewing recent alloy development it is convenient to identify two main lines in terms of the metallurgical structures involved, since these tend to define the more appropriate areas for design interest.
Low Speed Handling with Special Reference to the Super Stall
Authors: Trubshaw E. B.
Published: July 2016

The title of this paper was chosen some time ago. In view of events experienced over the past three years on some modern civil jet transports, I propose to devote the time available to the subject of stall characteristics, together with some of the associated problems and with the methods of solution.

Before anyone else raises the point, I wish to point out that the term “Super Stall” is nothing more than popular jargon and is equally as objectionable to the purists as “Deep Stall” or “Stable Stall”. It will, I hope, become clearer later as to what particular characteristics these terms apply.
Some Aero Engine and other Reminiscences 1905-1918
Authors: Verney R. H.
Published: July 2016

I have always been an enthusiast for engines, even before 1913 when after a flight with Geoffrey de Havilland in a BE2a, I took my ticket in a Caudron biplane at Hendon, enjoying a little thrust, and much castor oil from the “Y” Anzani engine. When I completed my figure of eight, nose well down on the turns, the only engine control—the switch—failed, so I foreshadowed my technical future by kicking off the petrol tap! Before that I Was acquainted with engines in the motor trade. I was mechanic in the Maudslay car in the first Tourist Trophy Race of 1905; our engine ran well till it became a bit short of petrol and ate its butterfly throttle. But, in 1907, I drove their first live axle car in the Scottish Reliability Trials, obtaining a gold medal for a non-stop run.
The Fifth Halford Memorial Lecture
Authors: Harper R. H. T.
Published: July 2016

Although I deem it a great honour to have been asked to give this lecture I will be perfectly honest and tell you that for a long time I resisted. 1964 is an important landmark in the Hatfield Branch history. It has been in existence for a quarter of a century and the developments which have taken place during this period in the Aeronautical World have been remarkable. The lecture also ranks as a Halford Memorial Lecture and so I felt that someone far better qualified than myself was needed in order to do justice to the joint occasion. However, I finally agreed and I would like you to know that this was not because some sudden inspiration gave me confidence that I was the man for the job, but rather because I felt that as the Hatfield Branch had done so much for me I should try and do something in return.
Evaluation of the Heat Dissipated inside Compartments by Internal Structural Members on High Speed Aircraft
Authors: Le Claire R.
Published: July 2016

This note deals with an extension of the basic fin theory, as found in refs. 1 and 2, suitably modified to estimate the heat dissipated by internal structure such as consoles, floors, bulkheads, and so on. It also outlines the electrical analogy method applied to complex structures.
Aircraft
Authors: James D.
Published: July 2016

An Examination of the available data on aircraft unreliability, whether on civil or military aircraft shows quite clearly that the systems engineering is more troublesome than the structural engineering.

The statistics show that landing gear, brakes, hydraulics, fuel and air conditioning systems are all at fault to approximately the same degree. In addition equipments for which the airframe manufacturer is not directly responsible, are a frequent cause of trouble.

The aircraft manufacturers’ contribution to improving reliability must come from three directions.
Contracting in the Civil Fields—The Influence of Competition
Authors: Beverley E. L.
Published: July 2016

Three of the tenets of a Contracts Manager are (a) that he should not be seen, (b) he only speaks if spoken to, and (c) he ensures that every answer he gives is capable of being interpreted in three different ways. You can imagine, then, how embarrassing it is for me to make what is supposed to be a forthright statement to an audience which I imagine contains a number of customers and potential customers.

I suppose one of the most ulcer-making things that can happen to an airline management is to see a piece of brand new and expensive aircraft machinery sitting on the tarmac unserviceable. With the increasing cost of civil aircraft, profits can only be made by keeping them in the air at a high degree of utilisation.
Potential Traffic Demand in the London Area
Authors: Watson A. H.
Published: July 2016

The June 1963 Report of the Inter-Departmental Committee on the Third London Airport concluded that a third London Airport would be required in the early 1970's, and possibly a fourth soon after 1980. It also brought out that because of the large amounts of air space required for the sequencing areas and approach paths of each airport, and because of limitations imposed by the positioning of the main air traffic routeings, the choice of possible sites within reasonable distance of Central London for the third airport was severely restricted. In a postscript to the Report, it was recognised that after the third airport has taken over a further block of air space, the difficulty of siting a fourth airport would be even more severe.
Is the Aeronautical Industry Making the Best Use of its Graduates? A Discussion
Authors: Lickley R. L.
Published: July 2016

Summary:—

The question, as phrased, suggests there is an optimum method of using graduates; this in turn suggests that all graduates have untapped resources and are ready to learn all that can be put before them.

In my view, it can always be said of any industry that it does not make the best use of any specific grade of labour; good managements, of course, make much more effective use of their labour force than the bad ones.

Graduates vary tremendously in previous training, from say, a mathematics graduate straight from school and college, to a specialist aeronautical graduate with works experience in addition.
The Measurement of Peak Strain
Authors: Howard H. B.
Published: July 2016

It is shown that, in regions near peak strains, improved accuracy of measurement with a strain gauge or extensometer, can be obtained by taking readings over more than one distance including each point. A better estimate of the true strain can then be derived than will be given by a single reading. Peak errors in the region of 8 to 10 per cent can thus be reduced to 1 or 2 percent.

Two methods are described: one in which measurements are made at equal intervals along a line, keeping the gauge length constant; the other using different gauge lengths centred on the point concerned, the latter being suitable where a grid can be marked on the surface.
Technology and Air Power
Authors: Cockburn Robert
Published: July 2016

It is a great privilege to have been invited to give the 1963 Trenchard Memorial Lecture, and I welcome the opportunity to pay tribute to the memory of a great soldier and airman. Lord Trenchard's deep understanding of the meaning of air power, his single-minded insistence on its proper use, and his dedicated leadership of the Royal Air Force during its formative years, will continue to inspire successive generations of airmen. It is appropriate that the Royal Aeronautical Society's Trenchard Memorial Lecture should be given here at Henlow before an audience of young airmen; for it will be their responsibility to master the new techniques on which will depend the continued evolution of air power.
The Design of Contra-Rotating Fans
Authors: Collar A. R.
Published: July 2016

Rather more than twenty years ago the writer published a report on the design of wind tunnel fans: a single fan was implied. The report assumed that the pressure increment appropriate to a given axial wind velocity was known, having been either measured (e.g. on a model), or estimated from data such as the power factor of the wind tunnel. A preliminary calculation to determine rotational speed and solidity was followed by a detailed calculation of the appropriate blade angles; the detailed calculation involved the evaluation of the rotational inflow factor (here called a: in Ref. 1 it was denoted a2). Now most of the quantities involved are functions, implicit or explicit, of the rotational inflow factor, and it is not possible to evaluate it in closed form: some method such as cross-plotting for ranges of a at each radius, or successive approximation by a convergent process, is required. Ref. 1 advocated the latter method.
Structural Design of the X-15
Authors: Schleicher R. L.
Published: July 2016

The 1346th Lecture to be delivered before the Society, “Structural Design of the X-15”, by Dr. R. L. Schleicher, was given on 18th April 1963 in the Society's Lecture Theatre with Mr. B. S. Shenstone, M.A.Sc, F.R.Ae.S., F.A.I.A.A., F.C.A.S.L, in the Chair. Introducing the lecturer, Mr. Shenstone said that Dr. Schleicher was Manager, Structures Engineering, at the Los Angeles Division of North American Aviation, Inc., and he had been with the firm since its inception in 1934. Dr. Schleicher was a graduate of Villanova University and held a degree of B.S. in M.E., and his D.Sc. had been conferred on him in 1957. He had nearly 34 years experience in aircraft structures engineering beginning in 1929. He had been Chief Structures Engineer at North American Aviation, Inc. on all the aircraft designed and built by the Los Angeles Division of that company and that included the X-15. He was a member of the Society for Experimental Stress Analysis and an Associate Fellow of the A.I.A.A. From 1943 to 1958 he had been a member of a number of NACA (now NASA) Committees and Sub-committees and had written a number of technical papers. He was currently serving on an Advisory Committee on Aircraft Structures for the U.S. Air Forces.

They were indeed grateful to Dr. Schleicher for coming all this way to lecture.
Flexural Vibration of Rectangular Plates with Stiffeners Parallel to the Edges
Authors: Mahalingam S.
Published: July 2016

The basis of the procedure described in the paper is the replacement of the stiffeners by an approximately equivalent system of line springs. One of two methods may then be used to determine the natural frequencies. A rectangular plate with edge stiffeners, point-supported at the four corners, is used to demonstrate the application of the Rayleigh-Ritz method. Numerical results obtained are compared with known approximate solutions based on finite difference equations. A Holzer-type iteration is employed in the case of a plate with parallel stiffeners, where the two edges perpendicular to the stiffeners are simply supported, the other two edges having any combination of conditions.
The Progress of European Air Transport 1946–1961 with Particular Reference to B.E.A.
Authors:   Lord Douglas of Kirtleside
Published: July 2016

I count it a great honour to have been asked by the Royal Aeronautical Society to deliver the Seventeenth British Commonwealth Lecture. Reading down the list of previous performers in this rôle one feels that it is indeed an election to a very select company.

I have chosen as my subject for this lecture the post-war progress of air transport in Europe. The title may sound rather pedestrian, but I have two main reasons for choosing this theme. First there is the personal reason. I have been intimately associated with the development of air transport in Europe during the post-war period and I am very pleased to have an opportunity to set down a record of the developments which have taken place during those years. Moreover, my associations with European air transport go back to its very beginnings, as pilot of one of Europe’s—and the world’s—first scheduled air services in 1919. The second reason is broader. I welcome an opportunity to review the post-war progress of air transport in Europe because I think that this will show what a revolutionary change the industry has undergone within the relatively short space of fifteen years.
The Effects of Inlet Conditions on Incompressible Fluid Flow Through Conical Diffusers
Authors: Cockrell D. J. , Markland E.
Published: July 2016

In 1931 Peters showed that flow entry conditions had a marked effect on diffuser performance. Later, Winternitz and Ramsay indicated that the pressure recovery coefficient Cpof a conical diffuser might be regarded as a linear function of β(θ/d)ifor values of β(θ/d)iup to 0·1. This note draws attention to the fact that diffusers with much larger values of this parameter are of interest and presents some experimental and theoretical results. Work is continuing along the lines indicated.
Rectilinear Flight in a Non-Uniform Atmosphere
Authors: Annenberg R. H. W.
Published: July 2016

The equations showing how to correct for the effect of non-uniformity of the Atmosphere when computing the angle-of-climb (or descent) are well known and can be found in Refs. 1 and 2.

From Ref. 1, a climb at constant Mach number M implies a factor F on the Aircraft Weight to give the true angle-of-climbs (in our units for R) given by the expression
Cylindrical Bending of a Heated Long Rectangular Plate
Authors: Lieb Burton A.
Published: July 2016

The design of structures for operation at increasingly higher temperatures and under exposure to severe heating requires more detailed and more exact analysis to determine the most severe conditions under which a given structure is operationally effective. To meet this need, the following analysis has been devised, with the determination of stresses and deflections in plates due to non-uniform heating as its purpose. The analysis results also in the determination of the maximum loads which may be imposed on the supporting members by the plate due to its thermal deformations.
The State of the Art in Management Education Applicable to Aerospace Activities
Authors: East F. H.
Published: July 2016

The Aviation Group of the Ministry of Technology (formerly the Ministry of Aviation) is responsible for spending a large part of the country's defence budget, both in research and development on the one hand and production or procurement on the other. In addition, it has responsibilities in many non-defence fields, mainly, but not exclusively, in aerospace.

Few developments have been carried out entirely within the Ministry's own Establishments; almost all have required continuous co-operation between the Ministry and Industry. In the past the methods of management and collaboration and the relative responsibilities of the Ministry and Industry have varied with time, with the type of equipment to be developed, with the size of the development project and so on. But over the past ten years there has been a growing awareness of the need to put some system into the complex business of translating a requirement into a specification and a specification into a product within reasonable bounds of time and cost.
Aero-marine design and flying qualities of floatplanes and flying-boats
Authors: Stinton Darrol
Published: July 2016

Quite by chance after this lecture had been written I saw at first hand part of the fire-fighting operation in the Tanneron in the South of France using flying-boats. This provided an excellent point from which to begin.

On 23rd August 1986 a vast fire was started deliberately, it was alleged, in the valley of the River Siagne, between Grasse and Mandelieu. There was a strong mistral blowing at the time. It was brought under control two days later with the aid of a small force of around nine ‘Pelicans’: Canadair CL-215 flying-boats (Plate 1). Each aeroplane can scoop up over 5000 litres (more than five tons) of water, in 10 seconds while planing at 70 knots (Plate 2). At times three aircraft would land in loose formation to do so. In the end the fire, said to be the worst since 1706, was reported to have destroyed 10 000 hectares (say 25 000 acres) of farm, forest and homes. Four people died, 700 suffered from burns and asphyxia, 8000 were left homeless.
The Royal Aeronautical Society 1866 — 1966
Authors: Laurence Pritchard J.
Published: July 2016

Humanity with all its fearsWith all the hopes of future years,Is hanging breathless on thy Fate.Longfellow.

12th January 1966, is the one hundredth birthday of the Aeronautical Society of Great Britain.

The story of the first hundred years of the Aeronautical Society began with long data-less periods of unfulfilled hopes. Like the paradoxical supersonic aeroplanes which arrive at their destinations before they are timed to take off, the story of the Society was started fifty years before it began, by Sir George Cayley, who wrote a famous paper on Aerial Navigation, laying down the fundamental principles of heavier-than-air flight.
Some Airship Personalities
Authors: Cave-Browne-Cave T. R.
Published: July 2016

When Airship No. 1, which had been built at Barrow, was finally abandoned in 1912, her officers were sent to Farnborough as “The Naval Wing” to gain experience of the military airships and of the Royal Aircraft Factory where they were built. A German Parsival Airship, No. 4, and a French Astra Airship, No. 3, were bought by the Admiralty for the Naval Wing.

In 1913 I succeeded in getting transferred to the Naval Wing and I found in the Naval Mess a most inspiring community. Lieut. Commander N. F. Usborne was the dominant spirit.
The Aeronautical Research Council
Authors: Nayler J. L.
Published: July 2016

The Royal Aeronautical Society may well be considered as one of the more important founders of the science and practice of aeronautics, bearing in mind at the same time the work of Sir George Cayley. Other early claimants in the history of aeronautics are the Royal Aero Club on the sporting side and the Royal Aircraft Establishment, the latter known formerly as the Balloon Factory. These date back many years but so also does the Aeronautical Research Council (ARC), originally called the Advisory Committee for Aeronautics (ACA), which although not so old as the other bodies mentioned above, has had an unbroken history of some fifty-seven years.
My Early Days at the Royal Aircraft Factory 1914 Onwards
Authors: Stevens H. L.
Published: July 2016

Some time in the May term in 1914, in my third year, my Supervisor of Studies told me that Mervyn O'Gorman, Head of the Royal Aircraft Factory, as it then was, would be visiting Cambridge and staying with Charles Darwin and might be looking for staff. He offered to arrange a meeting for me if I was interested. I had intended to be a civil engineer, but we agreed that aviation was a coming profession and it would be a good idea to get in more or less on the ground floor.

I went to see O'Gorman, and it was eventually agreed that if I got a good place in the tripos I would be taken on at the Factory at a salary of £1 per week and would report on the 1st August.
1908 Onwards—
Authors: Gordon England E. C.
Published: July 2016

In 1965 we see a world around us seemingly inharmonious and suffering from uncertainty in the regions of religions, politics, economics and culture. How different away back in 1908! Most people in those far off days had convictions and held them to be first principles.

They really did believe in the verity of the words of the hymn from which this phrase is quoted—“God made them high and lowly and ordered their estate.” People in 1908 saw nothing peculiar in holding such beliefs. This was the atmosphere in which the activities of the Society were being conducted and was largely the matrix of the thinking of its illustrious and inspired membership.
British Rotorcraft
Authors: Hafner Raoul
Published: July 2016

This brief historical note on British rotorcraft may be likened to the small visible part of a large iceberg and the reasons for it are these.

When I was asked to write this note for the Society's Journal I agreed to undertake the task with certain reservations. In the first instance there was very little time in which to do it. While it was relatively easy to collect the early history from well-established records this did not apply to the more recent developments and here the material needed to be collected from primary sources and to be collated.
Civil Airworthiness
Authors: Tye Walter
Published: July 2016

This account of the development of civil airworthiness comes from one who has been closely concerned. It is therefore a somewhat personal view. However, a tree in the heart of a wood must be forgiven if it knows best the trees in its immediate vicinity and if its perspective of the whole wood is restricted.

I have tended to relate the history of airworthiness to the development of airworthiness regulations, chiefly because these events are more clearly marked historically.
The Primary Effect: Preference Votes and Political Promotions
Authors: FOLKE OLLE , PERSSON TORSTEN , RICKNE JOHANNA
Published: July 2016

In this analysis of how electoral rules and outcomes shape the internal organization of political parties, we make an analogy to primary elections to argue that parties use preference-vote tallies to identify popular politicians and promote them to positions of power. We document this behavior among parties in Sweden's semi-open-list system and in Brazil's open-list system. To identify a causal impact of preference votes, we exploit a regression discontinuity design around the threshold of winning the most preference votes on a party list. In our main case, Sweden, these narrow “primary winners” are at least 50% more likely to become local party leaders than their runners-up. Across individual politicians, the primary effect is present only for politicians who hold the first few positions on the list and when the preference-vote winner and runner-up have similar competence levels. Across party groups, the primary effect is the strongest in unthreatened governing parties.
Explicit Bounds for Approximation Rates of Boundary Crossing Probabilities for the Wiener Process
Authors: Borovkov K. , Novikov A.
Published: July 2016

We give explicit upper bounds for convergence rates when approximating both one- and two-sided general curvilinear boundary crossing probabilities for the Wiener process by similar probabilities for close boundaries of simpler form, for which computation of the boundary crossing probabilities is feasible. In particular, we partially generalize and improve results obtained by Pötzelberger and Wang in the case when the approximating boundaries are piecewise linear. Applications to barrier option pricing are also discussed.
On Optimality of Bold Play for Primitive Casinos in the Presence of Inflation
Authors: Chen Robert W. , Shepp Larry A. , Yao Yi-Ching , Zhang Cun-Hui
Published: July 2016

Mr. G owes $100 000 to a loan shark, and will be killed at dawn if the loan is not repaid in full. Mr. G has $20 000, but partial payments are not accepted, and he has no other source of income or credit. The loan shark owns a primitive casino where one can stake any amount in one's possession, gaining r times the stake with probability w and losing the stake with probability 1 - w (r > 0, 0 < w < 1). Mr. G is permitted to gamble at the casino, but each time he places a bet, the amount of his debt is increased by a factor of 1 + α (α ≥ 0). How should Mr. G gamble to maximize his chance of reaching his (moving) target and thereby surviving? Dubins and Savage showed that an optimal strategy is to stake boldly if the primitive casino is subfair or fair (i.e. w(1 + r) ≤ 1) and the inflation rate α is 0. Intuitively, a positive inflation rate would motivate Mr. G to try to reach his goal as quickly as possible, so it seems plausible that the bold strategy is optimal. However, Chen, Shepp, and Zame found that, surprisingly, the bold strategy is no longer optimal for subfair primitive casinos with inflation if both r > 1 and α satisfies 1/r ≤ α < r. They also conjectured that the bold strategy is optimal for subfair primitive casinos with inflation if r < 1. It is shown in the present paper that this conjecture is true provided that w ≤ ½. Furthermore, by introducing an interesting notion of sharp strategy, additional results are obtained on optimality of the bold strategy.
Extinction Probability in A Birth-Death Process with Killing
Authors: Van Doorn Erik A. , Zeifman Alexander I.
Published: July 2016

We study birth-death processes on the nonnegative integers, where {1, 2,…} is an irreducible class and 0 an absorbing state, with the additional feature that a transition to state 0 may occur from any state. We give a condition for absorption (extinction) to be certain and obtain the eventual absorption probabilities when absorption is not certain. We also study the rate of convergence, as t → ∞, of the probability of absorption at time t, and relate it to the common rate of convergence of the transition probabilities that do not involve state 0. Finally, we derive upper and lower bounds for the probability of absorption at time t by applying a technique that involves the logarithmic norm of an appropriately defined operator.
Multitype branching processes observing particles of a given type
Authors: Ceci Claudia , Gerardi Anna
Published: July 2016

A multitype branching process is presented in the framework of marked trees and its structure is studied by applying the strong branching property. In particular, the Markov property and the expression for the generator are derived for the process whose components are the numbers of particles of each type. The filtering of the whole population, observing the number of particles of a given type, is discussed. Weak uniqueness for the filtering equation and a recursive structure for the linearized filtering equation are proved under a suitable assumption on the reproduction law.
The lifetime of a random set
Authors: Kiessler Peter C. , Nimitkiatklai Kanoktip
Published: July 2016

We consider the lifetimes of systems that can be modeled as particles that move within a bounded region in ℝ
n
. Particles move within the set according to a random walk, and particles that leave the set are lost. We divide the set into equal cells and define the lifetime of the set as the time required for the number of particles in one of the cells to fall below a predetermined threshold. We show that the lifetime of the system, given a sufficiently large number of particles, is Weibull distributed.
Transient solution to the time-dependent multiserver Poisson queue
Authors: Margolius B. H.
Published: July 2016

We derive an integral equation for the transient probabilities and expected number in the queue for the multiserver queue with Poisson arrivals, exponential service for time-varying arrival and departure rates, and a time-varying number of servers. The method is a straightforward application of generating functions. We can express p

ĉ−1(t), the probability that ĉ − 1 customers are in the queue or being served, in terms of a Volterra equation of the second kind, where ĉ is the maximum number of servers working during the day. Each of the other transient probabilities is expressed in terms of integral equations in p

ĉ−1(t) and the transition probabilities of a certain time-dependent random walk. In this random walk, the rate of steps to the right equals the arrival rate of the queue and the rate of steps to the left equals the departure rate of the queue when all servers are busy.