PADIS is the acronym for the ‘procedure for analysing the design of interactive solutions ’.

If one may use the noun ‘paradigm ’ to mean that way of looking at a problem that permits a solution to that problem to be found, PADIS is both a paradigm for the design process, and a practical system of design management based on that paradigm, enabling important benefits to be realised.

Study of the requirements for a design management system had been under way since 1970, but after the fortuitous discovery of the paradigm early in 1977 it became possible to carry out focusing development, and in a succession of small scale experiments a much deeper understanding of the problem was obtained.

In the past, it has been generally accepted internationally that in order to land aircraft in runway visual ranges below 400 metres—ICAO Category 3 conditions—a fail operational automatic landing system is required. The Trident aircraft with its triplex system is of course an example of this philosophy. However, the overall system requirements for such operations were specified nearly a decade ago and considerable advances have been made since then on such aspects as understanding fog characteristics, avionic system design, visual aids and of course, airline experience of all-weather operations. Consequently, there is now a world-wide interest in trying to ease the system requirements without jeopardising safety, for example, by considering the use of less complex fail-passive autopilots. If feasible, this would allow existing suitably equipped aircraft to operate to lower minima and hopefully, widen the spectrum of aircraft capable of being equipped, with overall benefits in terms of increased regularity and hence revenue.

The continuation of mass travel over long distances, is inconceivable if the world really runs short of energy. Thus, looking at the year 2000 we have two alternatives:

either: fuel will be strictly rationed and reserved for essential purposes, which certainly would not include long-distance mass-travel,

or: fuel will continue to be freely available to the airlines at some price.

In the first scenario, there is no future for civil aviation as we know it and the aerospace industries must turn to new fields of endeavour.

In the second scenario, we have to answer the question: ‘what fuel at what price?'. This has to be answered because, if the price were to rise sufficiently, then the result would be similar to that of the first scenario as the present travelling public could no longer afford to buy airline tickets.

The discovery of the essential logic of engineering design through the development of the ‘procedure for analysing the design of interactive solutions’ (PADIS) has made it possible to prepare authoritative flowcharts for the design process. This deeper understanding has revealed that, for the design task overall, there is no unique flowchart but many. Each project study is inspired by a combination of up to five types of inspiration, and by appropriately combining the flowcharts given here, an individual flowchart can be determined for each design task undertaken.

At subordinate levels of design, it is true, the design process is normally stereotyped, but if invention or new knowledge encourages redesign there may be need to adopt different procedures.

Bell's Model 222 is an 8-10 place helicopter powered by two Lycoming LTS101-650C2 engines. It is the result of extensive engineering design studies. These studies considered several configurations including fore and aft engines, laterally disposed engines, two across seating, fixed landing gear, skid landing gear and JetRanger growth versions. Two full-scale mockups were built and thoroughly evaluated prior to selecting the final configuration. The mockup selected was used extensively for evaluation by Bell and by commercial customers resulting in additional refinements. The final configuration is shown in flight in Fig. 1.

The helicopter industry has been experiencing a dramatic conversion from a market which was almost completely dominated by the military, to one in which the civil customer is playing an ever increasing role. As part of this change there is an increasing demand for vehicles whose interior noise levels are substantially lower than those of their predecessors.

One of the most significant recent events in the area of helicopter noise has been an impending regulatory action, rather than a technological breakthrough. This action is the development of helicopter noise standards which are currently being considered simultaneously by the International Congress of Aeronautical Organisation's (ICAO) and by the Federal Aviation Administration (FAA) in the United States. Up to the present time the specification of external noise limits, if any, were either made by individual customers, based on a particular need, or by the designer and manufacturer who might try to forecast how noisy the aircraft could be and still meet market requirements. It is highly probable that the effect of the new standards will be to require future helicopters to be substantially quieter than many of the current models.

It is said that 1978 was a great year for the consumer: IATA's face was pushed in the mud; President Carter had a great new freedom of the skies policy; and the CAB had a new deregulation policy. At long last the consumer benefited from the massive new spread of low fares.

This is a gross exaggeration; low fares have been around for a long, long time. European inclusive tours, for instance, through the fifties, sixties and seventies, through trials and disasters, have grown to be a new way of life for the holidaymaker and vacationer from Northern Europe, who vacates Northern Europe en masse in the spring, in the summer, through the autumn and goes to the Mediterranean. No other way could that have been done without the promotion of low fares as part of a total package.

The discovery of oil in the North Sea has resulted in a rapid expansion of helicopter operations in the United Kingdom.

The pilots currently flying to and from oil rigs have either VFR ratings only or hold Certificates of Instrument Flying Competence. With the congestion of traffic in the North Sea area, there is clearly a requirement for increasing safety without further increases to traffic from training flights.

According to Flight (2nd September 1978), legislation is to be introduced to establish an Instrument Rating (Helicopters) with effect from April 1979. Many of the pilots now flying will need further training to achieve this rating.

British Airways Helicopters have installed a simulator for the Sikorsky S61N helicopter at Dyce airport, Aberdeen to facilitate training of pilots to fly the aircraft most commonly used for oil rig work. The simulator will be used for many aspects of training including instrument training.

Prior to 1937, responsibility for civil aviation in the UK, including airworthiness and operation of airships, was vested in the Air Ministry, a Government department, and it was only in 1937 that it was devolved to an independent authority, the Air Registration Board, which is now the Airworthiness Division of the CAA.

The first involvement of the CAA with airships occurred early in the present decade when it was confronted firstly with an extremely unorthodox configuration of airship. The Skyship project (Fig. 1) was 720 ft in diameter, 48 million cu ft in volume, and 400 tons pay-load capacity.

Even with today’s computers, a wind tunnel is an essential tool in engineering, both for model tests and basic research. Since the 1930s, when the strong effect of free-stream turbulence on shear layers became apparent, emphasis has been laid on wind tunnels with low levels of turbulence and unsteadiness. Consequently most high performance wind tunnels were designed as closed-circuit types (Fig. 1(a)) to ensure a controlled return flow. However, as will be seen below, it is possible with care to achieve high performance from an open-circuit tunnel, thus saving space and construction cost. ‘Blower’ tunnels (with the fan at entry to the tunnel, Fig. 1(b)) facilitate large changes in working section arrangements; to cope with the resulting large changes in operating conditions, a centrifugal fan is preferable to an axial one. For ease of changing working sections the exit diffuser is often omitted from small blower tunnels, at the cost of a power factor greater than unity. This paper concentrates on the design of small blower tunnels but most of the information is applicable to wind tunnels in general.

Previous papers, described the blast loads measured on a long, flat plate near the muzzle of an isolated rifle mounted in a wind tunnel at subsonic and supersonic speeds. For this idealised configuration, these measurements confirmed the validity of the approximate theory due to Frank Smith to predict the level of the blast loads from guns mounted on static or moving aircraft.

However, for real aircraft the gun is generally installed in a blister or fairing and the fuselage adjacent to the muzzle may have considerable curvature. These features, which are different for every installation, modify the blast wave in a way not easily amenable to calculation.

In the present paper the blast loads on the fuselage of a typical fighter aircraft near the muzzle of a cannon were measured in flight at subsonic, transonic and supersonic speeds.

Future developments and trends in the data processing industry will have an earlier and stronger impact on aerospace than upon any other segment of industry. The use of data processing by aerospace in scientific, administrative and automation applications typically precedes and anticipates that of society and industry at large. My discussion, therefore, will focus on the total use of data processing and its technologies in our industrial-based societies. First, I will present an overview of data processing in terms of usage and dollars, then look at the world of computers a decade hence from a user's and administrator's point of view. Then I will offer a view of that world of computers from a technologist's point of view, and finally, discuss the impact of such a scenario on our society.

The term data processing industry, as I will use it, includes all those who are involved in providing data processing capabilities: equipment and software manufacturers, programming and operations staffs of user installations, professional data processing organisations, and university and research computer science groups. In short, those who design and produce our computer-based systems and services.

One of the more important objectives of research in aerodynamics is drag reduction. In this paper we consider one part of the drag problem, the forebody pressure drag, and enquire about the lower limit to which it may theoretically be reduced by elimination of flow separation. It is customary to decompose the total drag force into two parts: pressure drag and friction drag, represented by force coefficients CD and CF, respectively. The ratio of these two forces may be taken as a convenient criterion to decide whether a body is ‘streamlined’ or ‘bluff’:

At high enough Reynolds numbers many bodies of interest are (according to this definition) bluff bodies, i.e. their pressure drag is much larger than the friction drag. This analysis is most relevant for bluff bodies where one needs to be concerned only with the pressure drag.

‘Active Control Technology’ (ACT) is a jargon of the last few years describing the technological requirements which permit the earlier concept of the Control Configured Vehicle (CCV). The CCV idea was that by suitably driving specially arranged controls, various desirable aircraft characteristics, notaby stability and good handling, could be provided synthetically and as a result the tail and fin sizes could be reduced and the wing mounted in a more advantageous position on the fuselage: more freedom of choice was thus given the designer in settling his configuration. The technology to do this was barely ready at the time but meanwhile has been progressing apace in the form of minicomputers, electrical signalling, digital control systems and a deeper analysis of what is involved in a total system.

The dispersal of droplets sprayed from an aircraft, be it fixed or rotary winged, is affected by influences which can be placed in four categories:

• 1. Particle characteristics e.g. terminal velocity.

• 2. Aircraft wake.

• 3. Meteorology.

• 4. Nozzle or atomiser position.

Although all four categories combine to produce a particular application the relative importance of each influence varies with particular circumstances. Large particles for instance, are little influenced by air movement and so aircraft wake and meteorology are unimportant. Small droplets, on the other hand, have low terminal velocities and are more easily affected by air movements. Situations where wake predominates over meteorology are usually those where flying heights and wind speeds are low. For example, in Ultra Low Volume spraying, Lawson and Uk (1979) found wake effects at low flying heights.

1. The training of airmen for trades in the ground electronics engineering trade group of the Royal Air Force, and in the trade which maintains flight simulators and other synthetic aviation trainers, is carried out at No 1 Radio School which since the early 1950s has been based at RAF Locking near Weston-super-Mare, in the County of Avon. This paper explains the RAF's requirement for a trade dedicated to Synthetic Trainer maintenance and how the training of that trade was planned and implemented.

2. In the early days of flight simulators the equipment used—of the Link trainer variety—was relatively simple using electrical and electro-pneumatic techniques. Maintenance was undertaken by electricians who received specialist training on the type to which they were assigned. With the development of sophisticated aircraft electronic instrumentation, radar, communications and weapons systems after the Second World War, flight simulators increased in complexity and servicing tradesmen were drawn from a variety of trades which themselves gave experience in electronics which provided essential background to undertaking simulator maintenance. The seven trades which donated tradesmen are shown in Fig. 1 which illustrates the range of basic skills used.

The purpose of this paper is to give a brief introduction to the scope, flexibility and power of the British Aerospace Numerical Master Geometry (NMG) System, which is a computer aid for the design and manufacture of complicated three-dimensional curved surfaces. NMG is currently used at all ex-BAC sites within the Aircraft Group of British Aerospace for the purpose of generating and storing master computer models of the external shapes of aircraft or components. These master models may then be interrogated using a simple command language to derive information about the external shape for such diverse uses as aerodynamic analysis, detail structural design, numerically controlled machining and inspection. The use of such models means that everyone has access to the same basic information, and consistency is assured.

The views I am putting forward today are my own I and may not represent the views of other independent airlines.

Low fares are not a new feature of the Civil Aviation industry. After all, charter airlines have been providing low cost air transportation for the past three decades, and what a painful process the development of those services has been. For years scheduled airlines, backed by Government regulatory agencies, subscribed to the theory that charter services, if liberalised, could lead to the destruction of scheduled services and therefore scheduled services should be protected. In the UK, the growth of Inclusive Tour Charters to points in Europe was slowed down by capacity restrictions and by pricing policies designed to minimise diversion of traffic from scheduled services.

The present note is concerned with the flexural vibrations of a thin elastic plate with variable rigidity and having the form of a sector of a circular ring. Plates of this shape have been rather sparsely treated in the literature.

The problem of free vibration of sectorial plates with radial edges simply supported has been investigated by Ramiah and Vijaykumar and by Ramakrishnan and Kunnukkasseril. For the case of a plate having clamped radial edges and the circumferential edges having any combination of boundary conditions, an approximate solution has been obtained by Bhattacharya. The free vibration of annular plates for various boundary conditions are summarised by Leissa. All these are for plates of constant thickness only.

Fatigue is a problem which all designers have to face. If they are starting on the design of an aeroplane, they will work out all the high loading cases first, make sure that the design will be good enough to meet them, then they will turn their thoughts to the survival of the proposed structure within the lower stress levels of everyday operations.

Some parts may see one cycle, some hundreds, many will see thousands, some millions and millions. All should function without cracking from fatigue.

If fatigue cracks do appear after some time, this indicates that while the design was reasonably close to optimum, it needs a little more material adding locally. The operator will probably groan at the cost and disruption the beefing-up operation will require, and the designer will be tempted to overdesign in the first place to avoid this situation.