§ LORD KENNET asked Her Majesty's Government:
§ What research into the reduction of aircraft engine noise has been carried out in the last two years at the National Gas Turbine Establishment at Pyestock, whether any forecasts of possible reductions have been made, and if made published, and if they have been made but not published, when they will be published.
§ LORD DRUMALBYN
My Lords, research on engine noise at the National Gas Turbine Establishment in the last two years has formed part of a continuing effort sustained over about fifteen years. Work is aimed at improving the appreciation of scientific principles and methods of prediction, and at solving the engineering problems involved. Topics studied in the last two years include all major sources of engine noise, including high speed jet noise and jet noise supressors; co-axial jet noise; compressor and turbine noise; tailpipe noise and appropriate absorbers for both tailpipe and intake noise; improved noise instrumentation. In addition, a new major acoustic test facility is nearing completion and part of it is now in use. The Establishment works in close co-operation with industry. Many people engaged in this and similar work have expressed personal opinions but the establishment has made no official forecasts of aero-engine noise reductions.