The up-to-date engineer or scientist would not challenge the growing importance of the modern large-scale digital computer in research and development. Yet, while we all agree that computers are important and useful, we disagree from one discipline to another and often within the same discipline on just what the computer contributes or can possibly contribute to research and development endeavours. The difference in approach to computer usage is more one of philosophy than of technique. Indications are given from our recent work that some philosophies of computer utilisation may be more fruitful than others. The availability of the large-scale digital computer has not only facilitated, but directly inspired and shaped the matrix methods for analysis of continuous media and structures, both in the linear and non-linear regimes. Without the availability of a modern computer all this work is literally meaningless.

Any system for controlling the airworthiness of aircraft engines in service should meet the following conditions:

• (a) it should be such that the incidence of in-flight shut-downs is kept to an acceptably low level;

• (b) it should ensure that aircraft are not flown with engines delivering significantly lower power than that used in establishing the scheduled Flight Manual performance; and

• (c) it should provide maximum protection against failures of a potentially catastrophic nature, regardless of probable incident rate.

In this paper, the foregoing principles are discussed in relation to experience with turbine engines in transport aircraft. Particular emphasis is placed on the importance of monitoring, by which is meant any procedure or device that can be used to determine engine condition in flight or on the ground. Some current trends in turbine engine overhaul policies are also reviewed briefly.

I would like to thank the directors of British Aircraft Corporation (Operating) Ltd for permission to give this lecture, but I must emphasise that the opinions expressed are my own. I would also like to acknowledge the considerable contribution that has been made by every Value Engineer in BAC to the pioneering work of introducing Value Engineering into our Corporation, and thank all those, both in BAC and in other aerospace companies in this country and in the United States, with whom I have discussed Value Engineering, and whose ideas have contributed to this paper.

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.

In the past few years, man powered flight has become a reality. The remarkable achievements in England by the Hatfield Man Powered Flight Group prove that man may take off and fly with his own muscle power without external aid.

Such a possibility seemed very remote to the early pioneers of man powered flight in the late thirties in Germany and Italy. Even after the Second World War, some of the designers of these pre-war aircraft still believed that the take-off of a man powered aircraft would never be possible without some outside assistance.

Present aerospace development work is done in an environment which demands success. This has stimulated interest in methods of planning and controlling project development and costs more positively.

While some developers continue to hold the view that planning other than in the broadest terms is not compatible with high novelty development, the importance of new planning attitudes has been recognised. However, the very magnitude of a major aerospace project is such that the application of new planning and control procedures may in itself constitute a significant development programme, and it is not surprising that the industry has shown caution in introducing major changes of method.

I had the privilege and pleasure of working directly under Roy Chad wick from 1942 until the time of his death in 1947. I use the word “pleasure” advisedly, for he seemed at that time to be the most unreasonable of men. At one moment he would be full of charm and consideration, and at the next a martinet who drove us well beyond what we mistakenly thought to be the limits of human endurance. I well remember standing in Oldham Street on a cold Manchester war-time morning, having missed all reasonable buses to Chadderton, to be picked up by Chadwick in a shiny Armstrong-Siddeley. All the way out to the factory he talked about the good old days of aviation, and the challenge of my chosen profession. At the front door we were welcomed by the commissionaire, and I went to my desk confident that God was in his Heaven and all right with the world. Within ten minutes the telephone—Miss Jackson summoning me to Mr. Chadwick's presence. As I entered his office he scowled at me and started in—“Lindley —you were late this morning ….”.

The Society holds the view that the greatest source of weakness in the conduct of British aerospace affairs is the lack of continuous comprehensive co-ordination of the planning of the programme. Planning is proceeding in various ways in Ministries, industry, airlines and elsewhere. These efforts are inadequately co-ordinated and are incomplete especially in relation to the long term future. What is required is the gathering together, efficiently, of all the results of the planning by the customers and the industry, the filling of gaps in this planning and the moulding of all these into a rational, comprehensive and acceptable whole.

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.“

In trying to decide how best to lay out a paper for this Symposium one is conscious of a great deal of information lurking in the back of one's mind, resulting from the sort of discussion that we all have after flight, or on those frequent occasions when the weather or other exigencies delay us in our task, but I wonder just what real value would be served if too many of our contemporary problems were to be aired in public? I have no doubt that before the day is out a fair amount of soul searching will have to be done on all sides, but particularly at this time when, for one reason or another, the order books for significant British aeroplanes are far from full, I think it is a time to discuss our problems freely, but with a positive objective in sight, the furtherance of British Aviation in the world. If the symposium has brought people together who do not frequently meet “in mass” it could be that there might begin a better understanding between us, in which case our time today will have been well spent.

Progress in understanding the atmosphere heating problems of space vehicles at hyperbolic entry speeds is reviewed. The various sources of aerodynamic heating are discussed along with the response of suitable heat shield materials to these inputs. It is shown that even for optimum shaped vehicles the problems are formidable at entry speeds greatly in excess of Earth parabolic speed. Much additional research, particularly of ablation materials, will be needed to effect satisfactory designs for such craft.

In most one-parameter methods of calculating laminar boundary layers it is assumed that the non-dimensional parameters H=δ1/δ2, I=δ2τW/μu1 and L = 2{I−λ(H+2)}, depend only upon the pressure gradient parameter λ=u1δ22/v. In this paper it is shown theoretically that a more accurate, two-parameter representation is

L=F0(λ)−μG0(λ)

I2=F1(λ)−μG1(λ),

where μ=λ2U1U1/(U1)2. Careful examination of the available range of exact solutions of the boundary layer equations has enabled the four functions F0, G0, F1, G1, to be tabulated, and the above functional forms agree with the exact solutions to a remarkable accuracy.

In view of the fact that a reasonable first approximation to L is usually , we write

,

and it is then shown that the momentum integral equation becomes

This equation is easily solved by iteration, setting g=0 in the first approximation, and convergence is extremely rapid.

The method is, in effect, a refinement of that due to Thwaites, which is universally accepted as one of the better of the existing calculation methods. Detailed calculations made by the present method indicate that the errors are only 5% of those given by the Thwaites method.

The pattern of flow at low Reynolds Numbers about an aerofoil in a cascade has been illustrated by the hydrogen-bubble flow-visualisation technique. The method has also been adapted tor the accurate experimental determination of the position of boundary-layer separation. Results of the investigation are presented graphically together with photographs showing the general behaviour of the flow in the wake.

According to the Plowden report, the American worker has weekly earnings of 2 to 2 times those of the British worker. The report also stated that, for the same production run (of 100 aircraft), the average cost in the USA would be between 105 and 115 per cent of the British cost for the same aircraft. This means that the number of man-hours expended in Britain is of the order of 2 to 2 times the number of man-hours taken in the USA for the same job. Or, it means that, if we could make an aircraft in Britain for the same man-hours as in the USA, it could sell at only 40 to 50 per cent of the American equivalent. But bear in mind that the man-hours I refer to are for all employees, not just those usually charged direct.

The Death of Miss Bradfield on 26th February 1967 at her home in Swanage will be regretted by a wide circle of friends. There can be few in the aerodynamic world of her generation who have not been influenced by her in one way or another and many will remember her with deep gratitude.

Born in 1895, the daughter of an eminent Wesleyan minister, she spent her early years in Ilkley, Yorkshire, and Wesleyan thinking and Yorkshire attitudes were ever prominent in her life. She read Mathematics at Cambridge, graduating as a Senior Wrangler at a time when the University would not yet confer degrees on women. Many of her early papers, therefore, have “Math, and Nat. Sci. Tripos” after her name. This experience may account for the somewhat pugnacious element in a personality which so impressively, stood out among so many men.

Modern weapons are very powerful. They may be very spectacular. They make news.

They are also very complex. They cost a lot of money. This, too, makes news.

Doing something complex and expensive usually takes a long time. This is not news. It only becomes news, then, if something sudden or unexpected happens—like a crash or a cancellation.

Sometimes it seems that, for such projects, the press look on no news as bad news; and bad news is good news for a reporter.

The art of project management is to ensure that nothing is entirely unexpected. This may not be newsworthy, but it should be economic.

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.)

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.

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.