Nearfield directivity analysis during the NG-19 launch

In August 2023, the Antares 230 launched successfully for the NG-19 resupply mission to the International Space Station. Acoustic measurements were taken at various locations around the launch pad, ranging from 60 to 200 m away from the vehicle. The analysis focused on azimuthal and polar angles to investigate the vehicle's sound directivity during the launch. Spectral data were evaluated as functions of frequency, angular position around the pad, and orientation relative to the vehicle. A spatio-spectral analysis was conducted to interpret the data effectively. Initial findings reveal that maximum sound levels are associated with wider angles relative to the plume for stations closer to the source. The peak frequency at all stations was observed to be between 20 and 60 Hz, which is common for vehicles of this size. Although proximity to the rocket complicates distinguishing between angles, making directivity analysis challenging, a spatio-spectral analysis best reveals the spectral features of the noise.