The advent of the high altitude supersonic aircraft has brought in its train a whole host of complex control problems. As far as the engine manufacture is concerned, these are perhaps best indicated in the diagrammatic layout shown in Fig. 1

It is not my intention however, to go into the question of multiplicity of controls and their proper co-ordination, nor will I venture into the abstruse province of stability. I should like instead to concentrate on the fuel system itself, i.e. the supply and control of fuel to the main engine combustion chamber.

The effects of aviation on the environment are becoming increasingly important. The world's airlines already have thousands of aircraft serving the passenger and freight markets and the market demand is still increasing. Unless steps are taken to address the problems created by aircraft noise and emissions, the future progress of the air transport industry will be inhibited.

The seriousness of the topic and the factual nature of the Technology Sub Group report are the reasons why this special issue of The Aeronautical Journal is being devoted to “Greener by Design”. Although the report has been carefully read by a number of people outside the Sub Group, it has not been refereed in the normal way (though a number of minor numerical changes have been made to the tables and text of the original report, partly to correct errors and partly for internal consistency). The reports from the other two Sub Groups, covering operations and market-based options, together with the Summary for Policymakers of the Technology Sub Group, will be issued shortly in a single volume but will not necessarily be published in The Aeronautical Journal.

The paper reviews the development of amphibious hovercraft and considers the noise emission levels of current types of in-service craft. A brief reference is also made to side wall hovercraft and hover barges.

An outline of suggested methods for quantitative measurement of noise level and format is given, should legislation be deemed necessary at some future date.

Finally recommendations are made for further research and development programmes aimed at achieving significant improvement in the next generation of hovercraft.

This paper describes the current status of knowledge regarding the impact of aviation on the atmosphere. The growth of the aviation industry is likely to continue in the future and at present there are significant concerns that this will adversely affect climate and local air quality in the vicinity of airports. Indeed, it is possible that air quality may become a constraint to increased capacity of some large hub airports. Currently the radiative forcing impact from aircraft emissions, other than CO2, are not accounted for in the International Civil Aviation Organization emission trading scheme proposals. Taking only this approach, emissions trading could, in theory, increase the radiative forcing, rather than decrease it. The study of improved ‘environmentally friendly’ flight is still in its infancy, however any proposed and actual new developments, in terms of technology and operational practice, should include an environmental assessment.

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.

The Paper describes a metal and composite recurrent cost model of a large civil aircraft wing structure for a multidisciplinary design, analysis and optimisation (MDO) environment. The work was part of a recent European MDO project (BE95-2056) which investigated methods for the integration of structures, aerodynamics, dynamics and manufacturing cost at the preliminary design stage.

The paper discusses the cost modelling approach, which is based on parametric and process cost model methods, and the integration of the cost models into an MDO process. Results for the cost models are shown.

A framework has been successfully developed which allows the incorporation of manufacturing cost models into an MDO environment. It allows a designer to evaluate cost changes with respect to specific design changes such as rib pitch, stringer pitch, wing area and wing sweep.

Three subjects have been selected for discussion in this paper, each of which has a major influence on aircraft design and operating economics. These subjects are airfield performance, noise and aircraft utilisation.

For an aircraft to have good operating economics it must be able to operate with a high load factor over a large percentage of the routes on which it is to be used. The permissible take-off or landing weight, and hence the payload, can be limited by any one of many airworthiness requirements. These include take-off distance and climb, landing distance and climb, and obstacle clearance in the vicinity of the airport.

This paper relates to a recent project in which the aim was to devise a procedure that could be used to identify the linearised transfer functions of the longitudinal motion of the solar powered airship Lotte from flight test data.

Using a non-linear mathematical model of the Airship, a linearised state space model was derived numerically and this was used to derive the response transfer functions, which formed the theoretical results. A test procedure was then developed to identify the transfer functions experimentally from frequency response data obtained in simulated flight tests. Initially, the linearised model was used and the test procedure was refined until a suitable level of coherence between the experimental and theoretical results was observed. The test procedure was then applied to simulated flight test data from the non-linear model, and finally sensor noise was added in order to represent actual flight test conditions as closely as possible. Unfortunately, the results were inaccurate and in some cases, they were unacceptable. When the test procedure was applied to the non-linear model, significant errors were seen in all the results. The addition of sensor noise led to heavily distorted results and a further degradation of the resulting transfer function estimates.

It was concluded that meaningful results could not be achieved unless frequency response data with a higher resolution could be obtained and the effects of sensor noise could be reduced. Presently, no test procedure has been developed that would be of any use in a practical situation. However, a number of ways of possibly improving the test procedure or otherwise improving the quality of the results were conceived near the end of the project. It is therefore the purpose of this paper to account for the shortcomings that were encountered in the project and to introduce briefly the unexplored remedies, in the hope that these may be of some benefit to future identification studies.

— A great deal of publicity has been given in recent years to the problems caused by microbiological attack on aviation fuels, although there had been considerable experience of the subject before the first serious problems arose in aviation. Intensive studies of the nature of the attack have shown that although limited use of biocides has been successful, the best control is by the elimination of stagnant water from the fuel supply system and the aircraft fuel system.

Today we speak of the quality of life and the need to improve the quality of the environment. The removal of all kinds of pollution from our environment is a laudable aim and for some types of pollution positive action and an awareness of the problem can make improvements with a minimum of cost. However, in the case of most forms of pollution, and this includes noise, improvement in the quality of the environment can only proceed at a price. Thus there is considerable need for phased reductions in pollution and future planning with imposed realistic targets is paramount. In this region of social planning the problem of cost benefit analysis cannot always be applied and pressures are exerted to directing funds for economic gains and combating other pressures in national and international life in directions which lead away from pollution control. Nevertheless improvements to the environment dependent on the supply of finance can only be achieved, all other things being equal, when the economic state of a country is stable and attention of governments is directed with a willingness to achieve what at first sight is a downright impossibility.

The development of the jet engine produced jet noise problems. Most of the understanding of jet noise was and is performed in universities. The fundamental and quite exceptional work of Lighthill was followed by that of Curie. Powell and Ffowcs Williams at Southampton in the early 1950s and was paralleled by experimental investigations on noise suppression by for example. Lilley at Cranfield. This university work was used to form the basis of a programme of research into jet engine noise at Ministry of Aviation establishments with considerable university inputs which established a commanding lead for the United Kingdom in the understanding of jet noise.

The formation of the Institute of Sound and Vibration Research at the University of Southampton under the inspiration of Professor E. J. Richards was a step which placed university research at a different level to that usually observed in the United Kingdom by concentrating in one place some 40-50 people all devoted to research and postgraduate education.

What do we mean by reliability? Mathematically, it is the probability that a piece of equipment will be capable of working when called upon to do so for the time required and under the environment specified, and, if we know the mean time between failures and make certain assumptions about the randomness of the failures, we can derive expressions that will give numerical values of inherent reliability.

In layman's terms, we can say that it is the ability of a piece of equipment, whether it be a small component or a complete aircraft, to be ready to work and to continue to work in the environment for which it has been designed, for as long as the specification requires it to do so and to do this with the minimum amount of maintenance.

The aviation industry plays a critical role in modern society, supporting global, regional and local economies and facilitating long distance travel for business and leisure. However the environmental impact of the industry is significant and this threatens the sustainability of future growth and the consequential benefits which could arise from it. Technological, operational and infrastructure improvements designed to reduce emissions and noise from aircraft are continually being eroded by the rapid growth of the industry, with the result that the environmental impact of air travel is increasing. Consequently, the sustainable development of the aviation industry will require that in future, technological innovation and fleet replacement continues at a rapid pace and that the highest priority is given to achieving a ‘step change’ in aircraft technology.

More than ten years of development have gone into the Rolls-Royce wide-chord fan, which will provide a 2½ per cent fuel saving when it enters service in 1984. This new and highly efficient fan is one of the advanced features of the 535E4 engine, which will have a fuel consumption 10 per cent better than that of the initial Rolls-Royce engine for the Boeing 757, the 535C.

How has this advanced fan been developed and what are its advantages? This article surveys the reasons for its development and the factors involved in this technical advance pioneered by Rolls-Royce.

A new semi-empirical one-dimensional approach for the prediction of aeroengine combustor emissions is presented. The model features a high level of versatility, resulting in a remarkable correlation quality of measurement data of different combustors. This combustion model was modified to reflect the design characteristics of staged combustors. After implementation in an optimisation procedure it was used for staged combustor design studies. For a typical aeroengine application an optimised combustor design was derived with respect to a predefined criteria. Potential exchange rates of combustion efficiency versus NOx emissions by rematching the fuel split for different operating conditions at extreme points of the environmental envelope (ISA/hot day/cold day) of a modern commercial aircraft were investigated. Conclusions regarding the suitable operation of the combustor were drawn. Finally the effect of changed design constrains on the optimisation result was investigated.

Rolls-Royce aero engines are used by 200 airlines, 300 corporate customers and 77 armed forces. To date 34 000 aeroplane engines have been built and, in the time that it has taken you to read this far, 10 aircraft propelled by Rolls-Royce engines have taken off.

The business is located in Scotland, England and Ireland and in England stretches from Bristol to North Yorkshire with the main head office at Derby.

Theoretical reaction rate considerations normally require homogeneity of the mixture supply. An attempt—necessarily crude by reason of the analytical difficulties—is made here to cater for the case of non-uniform fuel distribution. Assuming a point-source injector in a parallel pipe, the “loss” in reaction rate is calculated for a limited number of specimen cases.

The aeronautical industry has set for itself important environmental goals, creating the need of improved tools for measuring the polluting emissions generated by fuel burn. This paper describes a new method to estimate the fuel burn and the pollution generated by a landing approach and also for a missed approach procedure. Fuel emission estimations can be used to compare the costs of different routes. The method developed in this paper uses the Emissions Guide Book developed by the European Environment Agency as the needed database for the computations. This method gives estimations of the fuel burn and emissions, including the amounts of CO, NOx, HC, EICO, EINOx and EIHC for a given flight as its output. The flight computation is divided into two sections: one section for the aircraft's travelled distance and a second section for the time an aircraft flies under certain flight modes. Since this method computes the missed approach fuel and emissions contribution, it computes the burn for a given descent approach for a successful landing, as well as for the same descent approach with a missed approach procedure followed by a successful landing. These two landings are verified in a complete flight to study the missed approach contribution for a conventional mid-range flight. The results show that a descent with the missed approach procedure requires 5.7 times more fuel than a normal, successful descent. This extra fuel burn increases the pollution released to the atmosphere and would impact the airlines’ profit margin due to the added fuel costs and longer flight times, as well as any future economic measures imposed on the increased air and noise pollution.

The International Civil Aviation Organization (ICAO) Circular Cir 337 is the first step towards ICAO establishing an Aeroplane CO2 Emissions Standard to form part of Annex 16, Volume III to the Chicago Convention. It describes itself as ‘a work in progress’. This paper reviews Cir 337 against the background of flight physics, the published literature on aircraft fuel burn and CO2 emissions and the current practices of the aircraft and engine manufacturers and the airline operators. We have taken, as our starting point, the aim of ICAO to reduce the fuel used per revenue tonne-kilometre performed and argue that the Breguet range equation, which captures all the relevant flight physics, should be the basis of the metric system underpinning the standard. Our overall conclusion is that Cir 337 provides an excellent basis for the initial regulation of aviation's CO2 emissions and, further in the future, for developing measures to increase the fuel efficiency of the operational side of civil aviation. Our main criticism of the circular in its current form is that it does not address the ICAO goal of reducing fuel used per revenue tonne-kilometre performed and makes no reference to payload. This defect could be eliminated simply by omission of the exponent 0.24 of the Reference Geometric Factor (RGF) in the formula for the metric given in Chapter 2 (paragraph 2.2) of the circular. Retaining the RGF to the power unity in the metric and multiplying it by an appropriate value of the effective floor loading would convert it to what the 37th Assembly of ICAO called for – a statement of fuel used per revenue tonne-kilometre performed. Finally, correlating the amended metric against design range, as determined from the measured specific air range and the key certificated masses, provides a sound scientific basis for an initial regulation to cap passenger aircraft emissions.

This paper is intended as a general introduction to the requirements for future passenger aircraft design. The needs of the 21st century are addressed to meet the important requirements of the customer airlines as well as those of the general public. In particular, the impact on two traditional major requirements are reviewed, the Design Mission and the operating costs. The effect of aircraft on the environment and the increases in the cost of fuel will have a substantial effect on the way future aircraft are optimised. These demands are summarised before moving on to the basic equations affecting how the aircraft design must respond. Very similar targets driving research work have been set in both Europe and the United States, and some of the new technologies that we can expect to be incorporated are outlined. Finally, a glimpse is given of the possible future aircraft configurations we may see in the skies in response to the new demands.