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Airbus’ “Silent Secret” to Engine-Noise Reduction

02 September 2005

One of the composite devices of engine-noise reduction used on the A380 is being employed on Airbus' newest aircraft family, the A350.

The Airbus patented composite inlet will further improve the A350’s engine noise to such an extent that it will surpass that of the already whisper-quiet A380.

The new composite inlet was first developed for the double-deck A380 and is installed inside the engine nacelle delivered by Aircelle (part of the SAFRAN group) to optimise the airflow control inside this component and to reduce engine noise. This inlet constitutes a significant breakthrough in the reduction of engine noise as it is manufactured as a single component. Existing inlets are also made of composites but they are typically constructed from three panels whose overlapping joints create additional acoustic distortion resulting in greater engine noise.

The single piece inlet, whose diameter is similar to that of an A320 fuselage on the A380, is not only more efficient at absorbing sound due to its homogenous surface but it also generates significant weight savings. Specially designed to meet the aggressive weight and acoustic performance targets for the A380, the single piece acoustic panel is only 38 millimetres thick and yet absorbs a significant part of the total noise attributed to the aircraft. It is also strong, water and corrosion-resistant.

The technology contributes to the very stringent QC2 noise target at London Heathrow International Airport, which was one of Airbus’ principal requirements for the A380. This new inlet is the result of five years’ research and development that principally started in 1999 and took place in both the France and the UK, where performance checks were carried out.

Twenty-seven patents have been lodged at the American and European Patent Offices as a result of this new component, five of which relate to new manufacturing machinery.

While composites are classically moulded with manually operated machinery, the perfect aerodynamic shape and homogeneity of this inlet required a brand new, digitally-commanded machine to be created, developed and produced.

The inlet is fitted as standard on the A380 and will be certified for use with both powerplants on the Rolls Royce Trent 900 engine and the Engine Alliance’s GP7200A.

The result is that when it enters into service in the second half of 2006 the A380 will be three decibels less than the 747.

With the A380 in its flight test campaign, the nacelle inlet team is already working on the inlet to be used on Airbus’ newest aircraft, the twin-aisle, twin-engine A350. In addition, although the inlet itself has advanced acoustic technology, the team is focussed on the further development on an inlet versatile enough to be compatible with future engine technologies.






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