Correcting for ground reflections when measuring overall sound power level and acoustic radiation efficiency of rocket launches

• DOI: 10.1121/2.0001733
• Publication Date: 2023-04-07T00:30:05Z
• Authors: Grant W. Hart; Kent L. Gee
• Keywords: Rocket (weapon); Effective radiated power; Reflection; Radiation impedance

Historically the radiation efficiency of a rocket plume has been assumed to be 0.5%, but recent measurements have thrown this into some doubt. Determining sound power level is first step in characterizing its efficiency. Because from launch vehicle anisotropic, well-calibrated ground measurement stations are used, along with trajectory data, obtain power. Historically, effect reflections appears largely neglected literature, despite potential inflate overall levels (OAPWL) and therefore This study investigates likely finite-impedance on spectra, pressure (OASPL), levels. A single-parameter reflection model used an estimate for change OASPL spectrum based measured space launches. When correction applied OAPWL it produces nearly 3dB reduction, reducing by factor two. indicates probability that rockets past too high.