All quiet on the airport front

Researchers at Cambridge University and the Massachusetts Institute of Technology are to co-operate on a project to design the world’s quietest passenger jet.

UK and US researchers are to co-operate on a project to design the world’s quietest passenger jet.

Aircraft noise is now a major concern for the aerospace industry as more international airports impose local noise restrictions. The number of people seriously affected by aircraft noise in the UK is set to double over the next 30 years to 600,000, as airport capacity around London is expanded.

So far decibel levels have been tackled mainly by improving aircraft engine technology. While engineers at Cambridge University and Massachusetts Institute of Technology plan to continue this research, more importantly they will make noise reduction a criterion in the design of the whole aircraft, said Ann Dowling, professor of mechanical engineering at Cambridge University.

‘This will be the first time that anyone has really brought noise into the design of the aircraft,’ she said. ‘Much has already been done to cut noise levels but the aim of this project is to see how far we can go towards creating a silent aircraft.

‘We want to open up the design space and ask ourselves what the silent aircraft should look like.’

While a totally silent aircraft is unlikely, Dowling said it would be possible to create a passenger jet that was significantly less noisy than those flying today.

The project, which also involves Rolls-Royce and British Airways, will run for three years and investigate the possibility of mounting engines on top of the aircraft, which would necessitate a new airframe design.

The team will also look at the possibility of jets deploying their undercarriage as late as possible, as this adds to noise levels as they land.

High bypass ratios in turbofan engines will be investigated too. These offer quieter, more efficient performance but the high-diameter fans associated with these engines pose significant packaging and installation challenges. ‘We will also look at how you operate such an aircraft and what the business case is for developing it,’ said Dowling.

The project is waiting for funding clearance from Cambridge University and MIT, which is due in the next few weeks.