Acoustical Measurements of Static Tests of Clustered and Single-Nozzled Rocket Engines

Abstract

The predictions of the acoustic effects of the static firing of large rocket engines have usually been based upon such engine parameters as specific impulse, nozzle diameter, etc. However, the recent development of large clusters of smaller engines have introduced a new possible variant. Tests were performed using two 1.5-million-pound-thrust rocket systems—one with a single engine and one with a cluster of eight smaller rockets. The two systems, NASA's F-1 and Saturn S-1, use the same liquid fuel and were fired on the same test stand. It was also possible to equate most of the other engine parameters so to effect a comparison of the acoustical effects resulting from static tests of clustered and single-nozzled rockets. Acoustical data are presented in this paper, showing both the over-all and octave-band acoustic-power levels for both test configurations. The differences in near- and far-field directivities and in mechanical-to-acoustical conversion efficiencies are presented.