A symposium having AIDS as its topic must include descriptions of flight and ground hardware, software programmes, and logistic support. These are dealt with only incidentally in this paper which attempts to examine the role of AIDS in the total management programme of a major aircraft system—the propulsion system. It can be accepted without too much contention that AIDS equipment can now be adequately reliable and provide flight acquired data in virtually any desired form. It is the inventiveness and imagination of prime manufacturers and operators which is being challenged to make the best use of it. The carriage in flight of equipment which does not directly contribute to performance or payload, and can require anything up to its own weight in compensatory fuel, obviously needs careful examination; but knowledge and understanding of the propulsion system characteristics can be priceless in guiding a transport system or weapon system efficiently through its life cycle.

In the earlier military aircraft designed since the last war, equipments and systems were generally isolated, each performing its own function independently of the others. Methods of checking correct behaviour of the aircraft system were generally by means of switching on and operating the equipment under reasonably known conditions—that is, for example, observing that indicators showed the correct situation. The methods of flight testing where there was no ready display indication were simply go, no-go methods which generally speaking merely indicated that power was supplied to the equipment under examination. In the Canberra for instance although fairly reasonable space was available, airborne checking in-flight was fairly minimal, most of the system tests taking place prior to flight and in some cases prior to installation of the equipment. With the advent of more miniaturised electronics it was possible to achieve more integrated systems and also system testing, although the natural trend towards smaller and faster aircraft rendered space a premium and therefore such functions more difficult. In the Lightning aircraft there appeared for the first time a fully integrated flight control system which was potentially integrated with the radar system. Figure 1 is a flow diagram which shows a considerable amount of system inter-relationship. In addition there originated a requirement for an automatic test system which was developed and gave a first experience of the use of a complex computer in the testing field. The main problems associated with its use lay in the difficult and time-taking connection to the aircraft and the fact that build up of adverse tolerances in the equipment could result in the rejection of systems which were themselves flight worthy. These factors resulted in the system being only viable at second line. A considerable number of lessons were learnt, however, which have since been applied on a smaller but equally complex scale.

During the last 20 years flight simulation has become of increasing importance in commercial, military, and space applications because of the significant transfer of training experience to the actual flight task, and the economy in usage of equipments, personnel, and fuels. Simulation has also aided in the definition of man's capability to deal effectively with new and different flight control tasks especially in space flight. In the case of space flight no other means of astronaut training exists other than simulation for much of the mission, a fact that NASA recognised in the beginning of the space programme. As a result a major effort has been made to obtain the highest simulation fidelity possible to insure the safety of each 'one of a kind’ space mission carried out. Link has been actively involved in the US space programme since 1962 when it employed simulation techniques to aid in astronaut training for Gemini flights. Shortly thereafter Link built three command module simulators and two lunar module simulators in which Apollo astronauts trained for their successful moon missions. Subsequently Link was selected to build the simulator in which astronauts trained for the Skylab missions, and was awarded NASA contracts for an Orbiter aeroflight simulator and a Shuttle mission simulator. The Orbiter aeroflight simulator has been functional since 1976 and has been in continuous use in preparation for the recent orbiter aeroflight tests at Edwards AFB, CA. The Shuttle mission simulator has been in design and construction since April 1976, and is scheduled for a phased delivery beginning early in 1978. It represents a major milestone in mission simulators in terms of sophistication, completeness, and magnitude of systems simulated.

The Flight Simulation Facility at the Warton Division of British Aerospace provides support for the design and development of advanced military aircraft. In fulfilling this rôle, opportunities often arise for innovation in the required flight simulation equipment. The combat simulator which we will describe is a good example of such an opportunity.

The practice of using flight simulators for research and development is well established, and the range of problems which are solved by this means is continually growing. Computers, which are at the heart of all simulators, are being improved at a remarkable rate, and improvements in other areas—electronic, hydraulic and mechanical, all contribute to more effective simulators. At the same time, the demand for simulation increases because the cost saving trade-off improves as the cost of flight testing to the ever-more-stringent design goals increases.

When one sits down and considers the title of this paper and its implications, I have no doubt that for most people and certainly for me, the word responsibility must conjure up a host of meanings largely depending on what sort of person one is, and what one's experience of life has been.

There is not any point in my talking about the ‘permission’ I would have thought, except to say for anyone in this audience who is unaware, that each operating Ag company negotiates with the CAA, in my view in a somewhat tedious way, for the issuance of this document; in it is set down the way the operator intends to run his show, and in effect it constitutes the rule book. Anyone here who is interested can obtain from the Cheltenham Stationery Office a copy of the guide to the Permission. Hitherto the permission has been free, but for this season it will cost £500 plus £300 for each aircraft on the register, no less, in line with the CAA's campaign to cover its costs.

The demand for aerial spraying is determined by agricultural needs and timing. The degree to which an aerially applied compound is effective is governed by many factors, which exercise their influence both at the time the compound is applied and for some time before and after this event. The impact of the weather and its interaction with other factors may be felt at all stages of relevance to an aerial spraying operation—these stages, which are of course also relevant to ground based spraying operations, may be categorised as follows:

• (i) The long term pre-spraying environment (measured on a time scale of days or weeks).

• (ii) The immediate pre-spraying environment (measured on a time scale of hours).

• (iii) Conditions at the time of spraying.

• (iv) The immediate post-spraying environment.

• (v) The long term post-spraying environment.

Calculations of the aerodynamic loads on wings in atmospheric gusts are an essential part of aircraft design for three main reasons. Firstly, an estimate of the gust loads which the aircraft must withstand is an important element of the structural design calculations in terms of ensuring both static load bearing capability and an adequate fatigue life. Secondly, the calculated gust loads provide the input to a suitable mathematical model of the aircraft structure in order to arrive at an assessment of aircraft accelerations and ride behaviour in expected levels of atmospheric turbulence. This is particularly significant for high speed military aircraft operating at low altitudes. Thirdly, aerodynamic loads due to gusts can be viewed as perturbing influences to aircraft stability so that the performance of an active control, gust alleviation or ride control system has to be considered with a detailed knowledge of the time variance of aerodynamic gust loads in mind.

The work to be described was planned as the first stage of an investigation of the effects of streamwise vortices on base pressure. An axi-symmetric blunt-based body was used, consisting of a cylindrical portion with a semiellipsoidal nose. The intention was to mount strakes or semi-delta wings at incidence on the sides of the body to produce vortices and to measure the effects of these on the base pressure. The base of the body was fitted with 37 pressure tappings so that local variations of base pressure could be explored. It was found that for the body at zero incidence and yaw, without any strakes or wings, there was great difficulty in obtaining an axi-symmetric distribution of pressure on the base.