ANCORA · ANotec-COmoti Rotorcraft Acoustics initiative for preliminary acoustic flight tests for the tuning of simplified rotorcraft noise models

One of the objectives of GRC5 is to implement a tool for the minimisation of noise impact on the ground, capable of being executed on-board “on-the-fly”, providing flight directives to the FMS of the helicopter. To this end reliable and fast noise predictions will have to be made, based on actual flight conditions. The envisaged semi-emperical model to be used for this purpose requires information to be derived from experimental data.The main objective of ANCORA is to determine the transfer function between the noise measured on-board the helicopter, close to the noise sources, and the noise received on the ground by a grid of microphones, during a flight test campaign.ANCORA will investigate the application of surface microphones on the helicopter fuselage and will subsequently use this knowledge for the flight test campaign.ANCORA will deliver a robust and reliable mobile noise measurement system, easily scalable and optimised for minimum deployment time and cost.During the test campaign a large number of steady-state conditions and manoeuvres will be flown over a grid consisting of 31 microphones.ANCORA will develop an advanced method for the determination of the transfer functions between on-board and ground microphonesAll results from the flight tests and data analysis (raw data, 1/3 octave spectra, transfer functions) will be made available through a data repository.""