§ 62. Mr. Biffenasked the Secretary of State for Trade and Industry to what extent the noise level of Concorde engines has been or is expected to be reduced by the application of spade silencers; and if 283W he will make a statement on this aspect of the development costs of the aircraft.
§ Mr. Michael HeseltineThe spade silencers have been found to be ineffective. Other features affecting Concorde's noise are still under investigation. The manufacturers remain confident that Concorde will achieve noise levels comparable with existing subsonic aircraft such as the Boeing 707 and VC10. So far over £40 million has been devoted to the investigation of Concorde's noise, but it is not possible to distinguish such specific items as the spade silencers.