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Keywords Aircraft engineering, Environmental issues, Design
A group including participants from every part of the aerospace industry, the Royal Aeronautical Society, environmentalists and government departments was formed in 2000 and became known as the Greener by Design Steering Group. Various sections were established; Operations, Technology, and Market-Based Options, of which Technology is significantly larger than the others and is the subject of this article.
Key questions are asked in the study on technology, which has been restricted essentially to subsonic jet transport aircraft. Its theme is the potential to mitigate the environmental impact of the continuing growth in air travel by the introduction of new technology and new design aspects. The environmental issues it addresses are noise, local air quality and climate change, the last named being taken as the most important in the long term. It has been addressed in the report by the creation of a set of 13 self-consistent aircraft design concepts, of differing levels of technology, which are compared in terms both of fuel burn and of radiative forcing of climate. The time horizon for the study is 2050. The main findings are outlined on each of the three issues.
Noise
Current noise regulation is contained in Chapter 3 of Annex 16 in ICAO, which specifies maximum noise levels at each of three defined measuring points: to the sideline of the runway at take-off; under the flight path at take-off; and under the flight path on final approach. At present some 90 per cent of the total civil fleet, passenger and freight, meet the Chapter 3 requirements. It is noteworthy that more than 20 per cent of the fleet, including all A340s and Boeing 777s, could meet a noise target l4dB below the Chapter 3 limits. Note that the rating is the sum of noise measurement at three points, so that, for example, a reduction of l4dB might be the sum of reductions of, say, 5db at the sideline and take-off flyover points and 4dB under the landing approach. In January 2001 CAEP/5 agreed on a total increase in stringency of 10dB, with a minimum of 2dB at each measuring point, to come into effect on new types certificated from 1 January 2006.
Since the beginning of the jet age, aircraft...