SILENCE(R) brings together a wide-ranging consortium to address the issue of aircraft noise, a major cause of concern around European airports. First, partners will carry out a large-scale validation programme, focusing on noise reduction technologies whose development was initiated by EU and National projects in 1998. Then, an assessment will be made of the applicability of these technologies within the European aeronautics industry, including their effects on cost, weight and performance. Finally, the associated achievable noise reduction will be evaluated.

Novel concepts to be validated are to include low-noise fans, LP turbines, scarfed intakes, novel intake liners, bypass and hot-stream liners, nozzle jet noise suppressors, active control techniques and airframe noise reduction technologies.

"The launch of the SILENCE(R) project is a clear sign of the European aeronautics industry's commitment to a quieter environment," says project co-ordinator Eugene Kors. "Increasing air traffic means more jobs and a stronger economy for Europe, and this project will help us to minimise the environmental downside."

"All of the major European air engine and airframe manufacturers are involved in the project," says Kors, "as well as the major research institutes and a number of universities. We have also been successful in including SMEs from around Europe. It was quite a task getting everyone together on this," he adds. "We now have companies working together which would normally be fierce commercial competitors."

SILENCE(R) is linked to X-Noise, a European Thematic Network on external aircraft noise and builds upon the results of other projects carried out under the Fourth and Fifth Framework Programmes, including: DUCAT, investigating computational methods for the propagation and radiation of turbofan noise; JEAN, concerned with the prediction of jet exhaust noise; RAIN, reducing airframe and installation noise; RANNTAC, developing low-noise turbofan engine nacelles; RESOUND, reducing noise within the engine itself; SOURDINE, proposing noise-reducing measures around airports; TURBONOISECFD, using Computational Fluid Dynamics (CFD) software to predict engine noise during the design phase. Together, these complementary projects represent a well-rounded programme aimed at reducing aircraft noise.

The air transport industry, over its history, has already achieved major reductions in the noise made by typical commercial jet aircraft. An aircraft entering the fleet today is typically 20dB quieter than a comparable aircraft of 30 years ago. In practice this corresponds to a reduction in noise annoyance of around 75%, with modern turbojets generating only 1% of the acoustic energy generated by the first commercial designs. Current research programmes are expected to deliver the technology for a further 10dB reduction within the next decade. A reduction of 10dB is perceived by the human ear as a halving of the noise experienced.

On 17 January 2001 in Montreal, the Committee on Aviation Environmental Protection (CAEP) of the International Civil Aviation Organization (ICAO) developed a comprehensive series of recommendations to reduce the environmental impact of aircraft noise. CAEP endorsed a balanced approach to noise mitigation, consisting of four distinct and complementary elements, including reduction of noise at source, and a new noise standard which is 10dB lower, on a cumulative basis, than the current standards.

Seen in this context, the SILENCE(R) project would seem to be an appropriately bold response, going a long way towards answering the call for the quieter aircraft of the future. The project's kick-off meeting took place in Copenhagen last April and was capped by a public session involving presentations by the European Commission and major industrial partners on the objectives and technical content of the project.

For information: Contact the X-Noise/SILENCE(R) communication manager Dominique Collin at dominique.collin@x-noise.net