Assessing Prediction and Reduction Technique of Lift-off Acoustics Using Epsilon Flight Data

Acoustic design of launch pad and prediction of full-scale acoustic environment are carried out by the numerical simulation and 1/42-scale model test for the Epsilon launch vehicle. Post-flight acoustic analysis of the Epsilon’s first flight is conducted. It is found that the acoustic level inside and outside the payload fairing satisfies the design requirement. The overall sound pressure level inside the payload fairing is achieved to be 132.3 dB without water injection system. Acoustic level outside the payload faring is reduced by 10 dB in compared with the former M-V launcher through the modification of the launch pad. The flight result reveals the effectiveness of the acoustic design methodology developed by the authors for acoustic attenuation at lift-off. Accuracy for predicting full-scale launch environment based on the results of the subscale model test and the numerical simulation is also assessed in this study.