My department's involvement in flight simulation started in the early 1960s under Professor Stephens. At that time, and even more so subsequently, what I think is an unusually high proportion of our staff had previous experience either as pilots, or in flight testing. Since 1965 we have operated our own light aircraft, primarily for flight test work at undergraduate level. In addition our links with the University Air Squadron are strong and the number of our students who are members is also exceptional. Every project described here, apart from one, was done by a pilot, or ex-pilot.

Our first project, for a PhD, was somewhat exploratory in nature, consisting as it did of three largely unrelated investigations. The first of these, suggested by two accidents involving aircraft on ground controlled approaches (GCA), was tackled using a fixed-base simulator consisting of a spring-loaded pitch control and throttle, and the usual flight instruments, all under a hood. I should explain that the GCA, particularly favoured by the military as an approach technique, consists of precision ground radar giving information of azimuth and elevation relative to the desired line of approach, to a ground controller. The ground controller then passes instructions to the pilot such as: ‘You are 30 ft below the glidepath. Adjust your rate of descent and turn left three degrees.’

The question posed by the symposium title is one of concern to many psychologists, especially those with interests in the study of high levels of human skill. The area of flight simulation does however present a number of challenges in terms of research questions, which are at present only partially answered.

There are at least three areas of simulator use where psychologists have interests and have a part to play:

• Man-machine system development

• Research simulators

• Training simulators.

The author and colleagues at the University of Sussex have been investigating technical problems related to the production of moving colour pictures representing real scenes in real-time. The object is to produce a visual system suitable for vehicle simulation. Flight simulation is generally the most difficult to achieve because of the need for freedom of movement and orientation in three-dimensional space coupled with a rapidly changing scene.

Such a system must therefore show smooth motion and reasonable realism. These factors imply a picture update rate of around 25 frames per second, the use of a wide range of colours and textures, a large terrain model, a picture generator capable of representing surfaces and a good mathematical aircraft performance model.

The relevance of this subject to the theme of today’s discussions lies in the fact that the universities play an important part in aerospace research and that significant research in the field of flight simulation can easily lead to the requirement for rather costly equipment which universities usually find difficult to obtain. This may well have been one of the major stumbling blocks preventing the universities from taking a more active part in flight simulation. The outsider may perhaps wonder why it seems to have been possible in the past to avoid some of these difficulties in the Netherlands.

Is flight simulation of academic interest? As we have a fairly substantial involvement at Cranfield, the answer must be ‘Yes'—although the amount of student involvement is small and our main activity is in contract work. This is explained later in the paper.

Most of the flight simulation work takes place in the Aeronautical Instrumentation and Data Processing Laboratories of the College of Aeronautics. Some takes place in the School of Electronic Systems Design.

Of all the branches of engineering, we regard aeronautical engineering as that which most needs simulation as an essential element of its constitution. Not even by choice may an aeronautical engineer be unfamiliar with simulation, for its advantages in the phases of design, production, and operation of aircraft are recognised by every aeronautical organisation, and its effectiveness, either in producing acceptable answers to flight problems, or in demonstrating flight characteristics, is the authority by which academics can insist upon the inclusion of the elements of simulation in their syllabuses. It is our belief that simulation has come to occupy this central position mainly as a result of the fundamental problems of safe flight.

The current decade has seen a major effort by European countries to achieve competitive status in the field of com-munication satellite systems. Effort and investment has been channelled by governments either nationally (the Italian Sirio Programme), bilaterally (the Franco-German Symphonie Programme) as well as through the multinational ESA, the European Space Agency (the OTS/ECS and Marecs Programmes). Europe is now at the crossroads of moving from the technological and preoperational phase, that has resulted from such programmes, to the implementation of operational systems responding to its own requirements. In addition, a technological base has been created in European industry capable of enabling it to compete for the worldwide market for regional and domestic systems that is now developing.

It was proposed in Ref. 1 that cryogenic temperatures can be achieved by the adiabatic isentropic expansion of a gas. The scheme is shown in Fig. 1. High pressure gas contained in A expands by means of valve 1 and cools. Valve 2 is then opened along with nozzle valve to push cold test gas through the working section.

In the ideal case the process is isentropic. To achieve reservoir conditions of T=120K and P = 4·4 bars, the initial pressure needed would be 110 bars. However, because of heat transfer from the walls of the tube, the process is not ideal and the actual initial pressure needed is higher. The main parameters which affect the heat transfer are the internal surface area of the tube, the rate of expansion governed by the size of valve 1 and the initial pressure of the gas.