09 July 2001

Slowing down faster could win aero-engineers £50,000

A team of engineers from Bombardier Aerospace in Belfast has been shortlisted for the UK's biggest engineering prize for their success in developing a new aircraft thrust reverser. Mike Hatrick, Keith Campbell, Edwin Beattie, Finbarr McEvoy and Joel Bennett have taken an idea patented by their peers in the 1970's and used it to create a thrust reverser that is more reliable and efficient than previous designs.

Several types of thrust reverser are used for jet engines, depending on the kind of aircraft and engine involved. All work by reversing the air flow using components in the nacelle - the cowling wrapped around the engine. Thrust reversers come into their own on wet runways, when the wheel brakes are not enough to slow the plane down as it lands, and during aborted take-offs when very little runway is left in which to stop.

The team started to develop their new thrust reverser in 1994 for Bombardier Aerospace's new CRJ-700 regional jet. This would use engines similar to those on the Challenger business jet from which it was derived, but the team had to come up with a new nacelle design to meet customer concerns over maintenance time as well as thrust reverse performance. In a globe-trotting design effort rotating between Belfast, Montreal, Boston and Cincinnati they have done just that. The new nacelle has already been used on Bombardier's CRJ-700 aircraft as well as the CRJ-900 and is in operation with regional airlines in Europe and North America.

Instead of relying on the conventional "blocker door" principle, in which a number of separate hinged doors inside the nacelle have to move to block the air flow, the new nacelle cleverly uses part of the nacelle cowling itself to reverse the thrust. This works because the team redesigned the nacelle fan duct into an "S" shape facilitating an elegant "natural" thrust reverse action free of many extra hinges and doors required in the conventional design. Fewer components means more reliable operation plus less maintenance and money saved.

Another problem the team has solved is access for maintenance: it took over 24 hours to change an engine with the original nacelle. With the new design this takes less than eight hours, thanks to an ingenious mounting arrangement that means the cowls that form the nacelle automatically find their own interfaces on the engine and line up correctly when they are closed. This saves hours of adjustment by trial-and-error. The cowlings are also counterweighted so that one person can open them easily, halving the time to access the engine. The two halves of the nacelle are mirror images of one another, so they can be used on left or right engines, thus minimising tooling costs and the number of spare parts required.

"We have commercialised the 'natural blockage' concept for thrust reversal for the first time," says Principal Powerplant Specialist Mike Hatrick. "It has been designed with both customer and environmental needs in mind. It is simpler than the old design, which improves reliability and maintainability. It also delivers 10 per cent more stopping force so the engines can run slower but give the same braking power. This is a great benefit as it reduces both environmental noise and wear and tear on the engine."

The Bombardier team will receive a MacRobert Award finalist certificate from HRH the Duke of Edinburgh on Monday 9 July at the Academy's AGM in London.

ends

Notes for editors

1. Britain's biggest engineering prize, the Royal Academy of Engineering MacRobert Award, is worth £50,000 and the MacRobert gold medal to the ultimate winner, who will be announced in November.
   
2. Bombardier Aerospace in Northern Ireland is one of three finalists for this year's MacRobert Award - the other two are Middlesex-based Sensaura Ltd for 3D audio and Brighton-based Southern Water plc for a novel separator for sewage treatment.
   
3. Bombardier Aerospace is the global leader in regional and business aircraft, and the world's third largest civil aircraft manufacturer. Its Northern Ireland facility is a centre of excellence for the design and manufacture of fuselages, nacelle systems and other aircraft components.
   
4. The Royal Academy of Engineering honours the UK's most distinguished engineers and aims to take advantage of the enormous wealth of engineering knowledge and experience that its one thousand Fellows possess. It exists to pursue, encourage and maintain excellence in the whole field of engineering to promote the advancement of the science, art and practice of engineering for the benefit of the public.

For more information please contact:

Jane Sutton at the Royal Academy of Engineering tel. 020 7227 0536 / 07989 513045

or

Helen Gregory at Bombardier Aerospace tel. 028 9046 2463

Links:

www.bombardier.com

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