Use of the bertin aérotrain for the investigation of flight effects on aircraft engine exhaust noise

A prototype of the Aérotrain has been modified by SNECMA and Société Bertin to investigate flight effects on jet noise and jet suppressor performance. To this end, special attention was given to the reduction of parasitic noise from the vehicle and internal noise from the GE-J85 turbojet engine which powers the Aérotrain. The vehicle, its performance, the operational techniques, the measurement and analysis procedures used are fully described, together with the results of the calibration tests of this unique and very flexible facility which presents many advantages compared to aircraft in flight. Typical results, consistent with the trends shown by clean aircraft noise data, are presented.