The preceding symposium papers have indicated the saleable developments on offer in the constituent parts of the civil transport system and their collective impact in aircraft project terms is covered in the paper by Brown and Lawson.

As the aircraft industry matures performance gains come less readily and costs have become a much greater determinant of progress. This paper therefore considers some of the fundamentals of cost reduction. This topic cannot be considered in isolation; cost reductions must be balanced against product effectiveness and there are major interactions between possible cost levels and sales volume. Thus, it is necessary to treat the subject in the broader framework of commercial viability. This paper attempts this task. It starts with the more direct cost questions, considers market interaction factors and concludes on a positive note by a critical review of the investment decisions needed, many of which are urgent and of critical importance to the future of the industry.

It has been known for many years that the rectangular wing stalls first in the central region, burbling spreading gradually tipwards with further increase of incidence. This phenomenon is useful in connection with lateral control, because this control is retained for a while (though reduced) past the stall. Increased use of the1 tapered wing to-day raises the question of whether this phenomenon holds good with tapered wings. There is already some doubt on this score.

These notes are intended to summarise for the benefit of aeronautical students the basic requirements of nose-wheel steering hydraulic systems. The various factors which have to be considered are listed and representative solutions given.

Through an analysis of TAWS/FMS data collected and registered during the last minute of TU-154M aircraft flight from Warsaw to Smolensk, we show the value and existence of space for undertaking research works on enhancing standard functionality of TAWS/FMS systems to enable their effective use in examination of the course and causes of air accidents. The flight ended up in the total destruction of the aircraft and the death of all passengers and crew on board. The TAWS/FMS flight altitudes and spatio-temporal data, i.e. geographical location and speed of the aircraft motion, were inspected for their internal and external consistency with the data from the ATM QAR service recorder. Using the data from ATM QAR, records from the cockpit voice recorder (CVR), jointly with data from the TAWS/FMS systems, it was possible to reconstruct the most probable horizontal and vertical trajectory of the TU-154M aircraft during the last minute of flight before its complete destruction, as well as the likely scenario of accompanying events. The data available from recorders enabled the authors to gain information on the preliminary stage of the course of accident, and the first phase of the aircraft's destruction, resulting in serious damage of the left wing of the aircraft. Enhanced standard functionality of TAWS/FMS systems, incorporating use of their data in the post-accident situations examination, would have improved results and simplified the present analysis considerably.

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.

Two philosophies for the attitude control of space vehicles with flexible appendages have appeared in the literature, these are:

1. (i) control of the rigid centre body to lie within some bounded region while the flexural vibrations are allowed to behave in an uncontrolled manner;

2. (ii) control of all plant states to some finite value as time tends to infinity.

The former method does not require flexural information and therefore avoids the on-board computational burden associated with state estimation, or the cost of additional instrumentation. However, attitude degradation has been observed and reported indicating a clear need to compensate for structural vibrations.

No one denies that speed is an essential to air travel. It seemed curious to me that air liners were operating at speeds varying from 100 to 150 miles an hour, and some months ago I set out to find a logical basis for determining the most economical speed of flight. I did not expect to arrive at an exact solution; but, rather to my surprise, I satisfied myself that I could give a general answer to most of the problems that interested me. I ventured to submit my calculations in a short memorandum to the Aeronautical Research Committee, and I had the privilege of meeting a sub-committee with whom I discussed my ideas. It was suggested that some further calculations on the same lines would be of interest, and it was proposed by Mr. Tizard, the Chairman of the main committee, that I should send a communication on the subject to the Aeronautical Society. The paper that I am reading to-night is the result of this suggestion.

A consideration of the factors suggesting that new types of flying instruments are becoming necessary.

To safeguard the aircraft and crew against the danger of excessive speed and normal acceleration loads, until recently it was considered sufficient to provide for the pilot an airspeed indicator and to fix in the aircraft a plate giving the maximum safe speeds permitted for diving, without and with external stores, flaps and undercarriage down and so on. In the case of Service aircraft these limitations are usually published in Pilot's Notes for the type. Based on design data these speeds are those at which, allowing suitable factors of safety, the stresses in the appropriate parts of the aircraft's structure are calculated to reach the maximum safe limits.

Dr. Rockey, in his interesting paper on the design of vertical stiffeners for shear webs, perpetuates the idea of Timoshenko (Theory of Elastic Stability, McGraw-Hill, New York, 1936) that for stiffener rigidities above a certain value the stiffeners remain straight and the rigid stiffener buckling load is reached. It is my opinion that this is only so when the stiffeners happen to be placed along a straight node of one of the harmonics of the buckling pattern of the unstiffened plate. With unstiffened plates under shear loads, the nodes are not straight and consequently the buckling load will theoretically always increase with increase of stiffener rigidity, i.e. no buckling mode exists such that stiffeners of finite rigidity remain straight. It is suspected that Timoshenko was led to his conclusion by over-estimated buckling loads obtained by energy methods.

When I was invited to deliver this paper it was suggested that I should adopt the title “Standards and Objectives for Air Safety”. I welcomed this idea because I think that now is an appropriate time to review our approach to air safety and I would like to discuss some of the modern developments in standards. On reflection, however, I felt that I should really make a small change to the title to put the objectives before the standards and I hope my hosts will forgive me for taking this liberty. I must confess that there have been many cases where the standards got written first and the objectives were worked out afterwards. But I would like to treat them here in the order in which I think they should appear.

I have been concerned for much of my working life with that part of safety called “airworthiness” but, as you probably know, it has been proposed that the ARB should now become part of a very much larger bureaucracy and so I hope my future colleagues will forgive me if I anticipate the merger with them and deal with safety in a rather broader sense.

Measurements of static pressure across the boundary layer on the wall of a circular cylinder with flow parallel to its axis display wall-interference effects which exceed corrections due to turbulence by almost an order of magnitude. Two different types of static pressure probe were investigated and gave different pressure distributions in the same boundary layer.

A commercial aircraft programme has always been an undertaking with significant risk. Accurately estimating potential sales and production costs of these aircraft is an essential part of containing this risk. This paper addresses the cost estimating process and cost management of the latest Boeing programme — the 757.

Substantial resources are required for a new programme. The number of people involved, of course, varies with the stage of production, but Boeing will employ approximately 10,000 at peak production rates. In a typical Boeing programme, a network of over 1000 suppliers of material, parts and equipment will employ another 20 000 people at peak production so that total employment is in the 30 000 range.

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

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

A linearised theory for the subsonic, lifting surface problem is formulated in terms of Fourier integral solutions to Laplace’s equation. The symmetric and anti-symmetric problems of the first kind are solved explicitly, while the problems of the second kind depend on the solution of dual integral equations. The antisymmetric problem of the second kind is cast in a variational form, from which certain well-known theorems may be deduced.

The development of aerodynamical research into the usefulness of wing profiles of various types for aerofoils of high aspect ratio lends special interest to new results in two-dimensional hydrodynamics relating to the motion of a perfect fluid in the presence of a cylindrical body, especially in the case when the curve of cross-section of the body possesses only a smali amount of camber and is cusped at one end and rounded at the other.

The possibility of formulating a theory which represents with reasonable accuracy the actual motions of aerofoils of high aspect ratio in a stream of air, when the air it taken to be inviscid, depends, of course, essentially in the first place on finding motions in which there is a force on the body at right angles to the direction of streaming. No theory which omits to produce this lifting force can give an account of the actual motions of aerofoils which is even approximately satisfactory.