Streamlined designs

September 25, 1998

University researchers are working with aerospace firms to bring aircraft to market more quickly and efficiently by improving knowledge-sharing and design, reports Kam Patel

Few industries are as brutally competitive as aerospace. And as aerospace firms push to produce better, more cost-effective products quicker, one of the most important, costly and demanding aspects of producing aircraft, engineering design, is coming under the spotlight.

The recently announced Pounds 1.5 million link-up between researchers at the universities of Sheffield, Southampton and Cambridge and aerospace giants Rolls-Royce and British Aerospace to develop an engineering design framework for the 21st century signals the two companies' serious intent to revamp the way they go about the business of design.

Ken Wallace, chairman of Cambridge's engineering design centre, one of the project partners, recites a litany of increasing pressures facing aerospace engineers: globalisation, shrinking product life cycles, rapidly changing technology and expanding knowledge base, increasing product complexity, rising customer expectations and soaring liability in terms of product liability and environmental issues.

Many industrial companies realise how crucial engineering design is to product development long-term profitability. He says: "It is estimated that 80 per cent of the costs of developing a product are committed after only 20 per cent of the total development costs have been spent. Design is one of the first stages of product development. Not surprisingly, there is growing interest in design research around the world."

Work at Cambridge will focus on computer-based systems for capturing, storing and sharing the knowledge accumulated by aerospace engineers through successive projects. But creating a system that can handle the vast amount of information is just one challenge for Wallace's team: "There are different ways in which the data is held, and yet we will need to have a common structure that everybody is familiar with and from which they extract information at the right time and in the right format - even the right language."

The system also has to help harness the creativity of designers, not stifle flair and imagination. "We would not want to get into a situation where the system inadvertently seduces designers into accepting past solutions to problems without them thinking about alternatives," Wallace says. "The challenge of coming up with new, elegant solutions to design problems must always be there."

BAe and Rolls-Royce are jointly backing the work of the university researchers because they face similar competitive and product development challenges from other firms. The overriding challenge for the early 21st century is to get aircraft to market quickly, says Richard Lees, research and technology project leader at BAe Airbus, the arm of the company involved in Europe's Airbus Industrie consortium.

But there are other benefits to be secured through slashing lead times, which for civil aircraft average about three years (down from five to six compared a decade ago) and about ten for military aircraft. "With reduced timescales we could in effect 'freeze' the design process much later in the production process, closer to the point where it is ready to go into service," Lees says. "This means we would be able to incorporate newer technology into aircraft designs much later than we are able to at the moment."

A novel inclusion in the research project is the expertise of a team of organisational psychologists at Sheffield University led by Chris Clegg. Based at the Economic and Social Research Council's centre for organisation and innovation, Professor Clegg's team will look at how the organisation of design teams at BAe and Rolls-Royce influences the adoption of new technologies and techniques and its impact on innovation of products, processes and working methods.

Professor Clegg says: "The introduction of new technology can disappoint because of organisational problems. Sometimes people get too much functionality and it overwhelms them, undermining the problems they were meant to alleviate. With a complex process, it is important to recognise that there are sociological as well as technical issues to be addressed."

Mr Lees also stresses the importance of creativity: "The emphasis in the past has been to minimise errors in the design process. While that remains crucial, what is increasingly being recognised is that we need to place just as much emphasis on creativity. I am not saying we would see revolutionary designs popping up all over the place if we did that, but at least the chances of some interesting and perhaps even radical solutions coming up would be that much greater."

Nofab_xy After a first in physics at King's London I began a PhD in rocket astronomy at the Mullard Space Science Laboratory of University College, London. I was involved in the planning, building, launch and analysis of data from instruments on two Skylark sounding rockets, which measured the smoothness of the cosmic X-ray background.

X-ray astronomy was very new, and I was fortunate to work on data from a small X-ray instrument package on the new Copernicus satellite soon after my PhD was finished. At Cambridge, I have built up a small group dedicated to the analysis and interpretation of X-ray astronomy data. My interests now concentrate on clusters of galaxies, active galactic nuclei and the X-ray background.

I have been intrigued by the X-ray emission peaks at the centres of many clusters of galaxies and the fact that the thermal energy of the 50 million degree hot gas there might be expected to be radiated away in a few billion years or less. This is less than the expected age of a cluster. The issue that I and others have been puzzling over for the past 20 years is what happens to the cooling gas. Recent data from the United States-Japanese satellite ASCA clearly shows cooler X-ray emitting components in these regions and the cooled gas. The rates at which the gas is inferred to cool mean that the halo of the massive galaxy at the centre of such a cooling flow may mostly be built out of the cooled gas. The problem is that we see little sign of the cooled gas in other wavebands. There is evidence for lots of mass in these regions, but it is mostly dark; we guess that the cooled gas forms some sort of dark matter.

Next January, a major Nasa X-ray satellite, AXAF, will be launched. I will use the AXAF telescope to examine cooling flows, the brightest extended extragalactic regions of X-ray emission. I anticipate spectacular results.

My other great interest is the search for black holes. Work in the radio and optical bands has shown compact masses that can only be black holes. But they probe only the regions beyond about 100,000 gravitational radii (the event horizon marking the extent of a non-spinning black hole is at 2 gravitational radii). The strength of the gravitational field there is not much greater than that on the Sun's surface, much less than the strong field in the near vicinity of the black hole. The variable X-ray emission from the nuclei of active galaxies has long been thought to come from the near region as the black hole accretes surrounding matter via a disk that gradually drains into the hole.

The key point for studying black holes is that X-ray irradiation of the material in the disk produces a fluorescent iron line at a particular wavelength. Doppler shifts, the special relativistic effects of aberration and time dilatation, and the general relativistic redshift combine to make the iron emission line seem to be broad and highly skewed toward the red. With others, I predicted the shape of the line over ten years ago and helped plan and analyse ASCA data, which clearly revealed it four years ago. The extent of the line shows that the emitting region is at about 6 to 20 gravitational radii, and possibly closer at times.

In about a year the European Space Agency will launch its big X-ray mission, and both Nasa and ESA plan larger instruments that will allow the broad iron line to be monitored as the X-rays flicker and flash, so mapping the immediate environment of a black hole. I am hopeful that strong gravity will then become an observational science.

A. C. Fabian is a Royal Society research professor in astronomy at the University of Cambridge.

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