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Figure 5. Left, a-h: noise maps superimposed on frames from an infrared camera, conventional beamform at 2 kHz; right: corresponding frames from a high-speed camera. Reproduced from Panda et al. (2013, Figure 11). See text for further explanation.
obvious difficulties in full-scale experiments, launch ve- hicle design is heavily reliant on scale-model testing, where the results can prove invaluable (Bies and Franken, 1961). A recent comparison between full-scale and model-scale data shows good correlation, indicating that scale data can be used with confidence (Giacomoni and Kenny, 2016). In- deed, a source localization and reconstruction technique has lately been employed to successfully analyze wall pressure measurements on a model launch vehicle (Casalino et al., 2012). Similarly, aerovibroacoustic methods are currently being developed for predicting the response of a rocket to the intense acoustic environment inside the nose cone used to protect the payload (Tsutsumi et al., 2016). Such research is of great importance in rocket design.
Recent efforts have also focused on collecting acoustic data from static-fire rocket tests in an attempt to characterize the full-scale rocket plume noise environment. The acous-
tic temperature has been measured in a rocket noise field and found to contribute significantly to the total tempera- ture variations (Giraud et al., 2010). Near-field vector inten- sity measurements on a model rocket motor indicate that as the frequency increases, the dominant source region contracts and moves upstream, with peak directivity occur- ring at greater angles from the plume axis (Gee et al., 2010). The noise source, conventionally assumed to be the rocket plume, is known to be directional and distributed and can be modeled by line arrays of monopoles that mimic the par- tially coherent nature of jet noise (Morgan et al., 2012). Re- cent work has shown that including source correlation and atmospheric turbulence in the model improves the predic- tions (Gee et al., 2014).
The first beamforming experiment conducted during an actual launch, in which microphones were placed on the rocket itself, confirmed the source distribution found dur-
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