Article - Issue 15, February/March 2003

Long-term planning in aerospace technology

Dr Mike Howse OBE FREng

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Few businesses have to plan their future development over such long time scales as the aerospace industry. Rolls-Royce has looked closely at the planning of its future strategy. Here Dr Mike Howse describes its approach.

In industries with a very long view such as aerospace, acquiring the right technologies at the right time is a business skill of vital importance to all the companies involved. Customers’ requirements change markedly over time according to market demands, corporate social responsibility in terms of the environment, and the increasingly stringent statutory requirements laid down by national and international legislation.

Long-term investment and long-range planning are vital, so Rolls-Royce has mapped out its research strategy, grouping technology acquisition within three broad time bands – up to around five years, around ten years, and up to 20 years and beyond. This it calls its Vision 5, Vision 10 and Vision 20 programmes.

The short term

Vision 5 includes near-term development such as that under way on the Trent 900 programme for the Airbus A380, but also embodies the improvement of existing products by incorporating new but proven technologies into them. An example is the insertion of the Trent high-pressure/ combustion module into the RB211 engine to enhance fuel efficiency and lower emissions.

A strategy of putting technologies ‘on the shelf’, available for use in new products, has already proved highly effective. It is a fundamental pillar in the ‘Derwent Process’, which Rolls-Royce applies when introducing all new products. Technologies finding their way onto ‘the shelf’ also carry the benefit of potential dual use. While developed for a particular purpose, a technology used initially in a civil engine may have equal or wider potential application in defence products – or vice versa.

Economies of scale accrue from concentrating on technologies offering the broadest overall benefits. Such an example would be the wide-chord fan blade, pioneered on the civil range of RB211 and Trent engines, but now applied to the latest military products – including the fan for the powerful engine used in the Joint Strike Fighter, on which the company collaborates with General Electric.

The medium term

Vision 10 technologies are those being validated for use in tomorrow’s engine products – such as metal matrix composites in compressor discs, which offer large weight savings, and which are already being manufactured and tested. An important part of the approach is to have a range of technology demonstration programmes aimed at delivering these ‘packages’ of technology: it is a low-risk approach that leads to products with market-leading performance, reliability and cost benefits.

Much Vision 10 effort is geared towards fuel efficiency, environmental improvements and life-cycle costs – gains that will result in a more competitive, and acceptable, product for the broader market. Rolls-Royce has declared targets to reduce fuel burn by 10%, reduce oxides of nitrogen (NOX) by 50% of the current legislative standard and reduce noise by 10 dB (effectively halving today’s levels) by 2010. This is ambitious when the aviation industry has already made such giant strides in reducing emission and noise levels since the jet age dawned little more than half a century ago. Engines are 70% more efficient, proportionally four times quieter and cleaner than they were then. To make further step-change improvements, the whole industry has to meet the challenges together. This collaborative approach has already begun in some areas.

Reducing emissions

Future emissions improvements will be developed and generated through the international ANTLE demonstrator (Advanced Near-Term Low Emissions) programme, supported by European Union funding, co-funded by industry and led by Rolls-Royce. This full-engine demonstrator will look at a wide variety of areas within the engine, mitigating risks associated with new technology acquisition. ANTLE will include further combustion technology research, continuing the development of staged combustor systems. The approach uses a direct injection, lean-burn single annular configuration, which delivers staged combustion but optimises the use of cooling air. The system is designed to more than double the air going into the primary zone of the combustor, resulting in reduced peak temperatures that will reduce NOX to 40% of current regulations.

Reducing noise

Noise-reduction initiatives have been undertaken with airframe and engine partners. These include SILENCE(R), a joint programme with Airbus, SNECMA and MTU. SILENCE(R) incorporates a negatively scarfed intake, optimised acoustic liners, nozzle-lip treatment, and designs of fan, turbine and outlet guide vane profiled for low noise. Many of these technologies will be progressively proven in ground-based tests on rigs, and on ANTLE, based on the Trent 500 engine. Others will ultimately be proven in a flight test programme.

Testing on a program with Boeing has been undertaken with modified engine exhaust nozzles and an advanced acoustic lining within the intake cowl. Static testing at the Rolls- Royce Hucknall facility proved successful and flight testing on a Boeing 777 showed significant reductions, exceeding expectations.

Other technologies

‘More electric’ technologies provide potentially increased functionality with reduced mechanical complexity, giving significant cost, weight and reliability benefits. Cabin air would be provided by a dedicated electrical system, replacing the engine bleed off-take. Conventional lubrication systems would be discarded in favour of oil-less magnetic bearings. These, together with a generator mounted directly onto the fan shaft to provide power for aircraft systems, encourage researchers to believe an airframe-integrated system could make significant reductions in fuel consumption. Further weight could be saved by avoiding the need for a separate emergency generator system and by moving to a distributed control system, incorporating local intelligent devices, coupled through digital technology to pylon-mounted systems away from the engine itself.

This technology area is another equally applicable to military aircraft systems – or marine applications, where electric systems would facilitate advances in ship design by allowing more flexibility in locating the gas turbine generators, leading to reduced cost and noise, and improved manoeuvrability. Indeed, more electric ship demonstrators are already well on the way. For full ‘more electric’ benefits, aircraft design will need to incorporate the same principles. The Power Optimised Aircraft (POA) programme, launched earlier this year, aims to maximise gains in fuel burn, air quality and reduced or eliminated subsystems. This will include a specific engine demonstration of the latest electrical technologies.

Underpinning all Vision 10 and Vision 20 programmes is the industry-wide planning that decides in which direction the business is moving. Senior Rolls- Royce research staff have to establish the shape and size of the foundation – both within the company and through its external links – for acquiring the technologies and processes required to achieve those broader business goals.

The long term

Vision 20 embodies a range of technologies aimed at the future generation of products in a 20-year timeframe. They are at the strategic research stage – emerging or as yet unproven – but the product-focused approach promotes the development of specific technologies through the company’s extensive research base. Much of this technology will be applied right across the company’s portfolio, including marine and energy as well as civil and defence aerospace products. Vision 20 goals will need to dovetail with broader European initiatives such as those being pursed by the Advisory Council for Aeronautic Research in Europe (ACARE), in which Rolls-Royce is participating.

ACARE’s own 2020 Vision programme foresees cutting by half the current perceived average noise levels, reducing carbon dioxide by 50%, and reducing NOX (classed as one of the key greenhouse gases promoted by aerospace activity) by a massive 80%. The realisation of these goals will come only through a collaborative approach, with aircraft makers, airlines, air traffic management and the engine manufacturers all playing their part. Meeting such targets is likely to be mandatory as the broader community sets legislation for ‘greener’ and more environmentally acceptable products.

Collaborative research

There is in place a strong global network of collaborative research links and in the UK there are 19 University Technology Centres (UTCs) conducting fundamental research, working to specific Rolls-Royce goals on long-term funded contracts. These contracts address engineering subjects as varied as vibration, noise, transmission systems, power engineering, combustion, control systems, aerothermal, performance, materials damping, advanced materials and manufacturing technology. UTCs are funded over several years, have an academic director, research fellows and assistants, and a co-ordinator from Rolls-Royce who sets and reinforces the goals of the research being undertaken. The business focus thereby remains very sharp, and mutual industry/academic benefits are more concrete.

The first international UTC in Europe was recently launched at Chalmers University at Gothenburg in Sweden, studying hydrodynamics in support of the marine business in which Rolls-Royce is a world leader. The company has forged longstanding engineering links with ten other major institutes in Scandinavia and Germany. Collaborative research into areas such as turbo-machinery and high-temperature materials is also conducted with some of North America’s foremost academic centres of technological excellence including Purdue (where the first USTC was established this year), MIT, Georgia Tech, Stanford and Penn State. In Asia, several institutes in China, Japan and Singapore are working collaboratively in combustion, powerplant integration, diagnostic and new material disciplines.

This structured, product-focused ‘Vision’ for the future means Rolls- Royce can continue to offer market-leading products with the latest technology, introduced at minimum risk, ensuring the company and the UK engineering base have a strong future.

Keep it quiet!

Within its Vision10 and Vision20 programmes, Rolls- Royce is involved in various research programmes into reducing noise and emissions from air travel.

In the noise arena, SILENCE(R) is being run as a European collaborative programme comprising Airbus, SNECMA and MTU, as well as Rolls-Royce, among its partners. Launched in 2001, it is the third integration phase of the European aircraft noise reduction campaign, and is expected to be complete in around 2005.

SILENCE(R) incorporates a number of novel features, notably a negatively scarfed intake to direct noise upwards, plus hot stream liners, nozzle lip treatment and optimised acoustic liners.

Technologies such as low noise fans and vanes will be validated in rigs and demonstration vehicles such as ANTLE (see the main text), while other technologies including liners and treated nozzles would be validated in flight aircraft.

Complementary research has been conducted with Boeing which involved modifying a Trent 800 engine with a package of technologies – including modified nozzles and advanced acoustic linings over an increased area of the intake cowl.

Static testing took p lace at Rolls-Royce’s Hucknall specialist test facility in Nottinghamshire in 1999, followed by flight testing on a Boeing 777 in 2001.

Targets originally set for the flight test were reductions in jet noise of 3 dB and fan noise of 7 dB. In fact, the results were 4 dB and 13 dB, respectively, demonstrating the level of improvements that are possible.

Such programmes are further supported by work undertaken by the company’s dedicated University Technology Centre at Southampton University’s world-renowned Institute of Sound & Vibration Research (ISVR) – and its own group of specialist engineers who are leading experts in this field.

Dr Mike Howse OBE FREng
Director – Engineering and Technology, Rolls-Royce PLC

Dr Mike Howse is the Director of Engineering and Technology – Civil Aerospace at Rolls Royce overseeing the wide range of in-service engines and the introduction of new Trent and other variants. He has worked for the company for over 30 years and is also a visiting professor at Cranfield University. He was awarded the OBE for services to aerospace.

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