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Methods and results of acoustical measurements made of a Delta IV Heavy launch

2021; Acoustical Society of America; Volume: 45; Linguagem: Inglês

10.1121/2.0001580

1939-800X

Grant W. Hart, Logan T. Mathews, Mark C. Anderson, J. Taggart Durrant, Michael S. Bassett, Samuel A. Olausson, Griffin Houston, Kent L. Gee,

Experimental and Theoretical Physics Studies

On April 26, 2021 the Brigham Young University (BYU) acoustics research group made a number of acoustic noise measurements during the launch of a Delta IV Heavy rocket from Vandenberg Space Force Base in California. The sensors ranged in distance from 330 m to 19 km from the launch site. Some sensors were arranged in a rough arc of 1-2 km radius and others were placed along both an east-west line and a north-south line. This enabled the measurement of the distribution of the noise in the different directions and at different distances. Two of the sensors were 5-meter radius, 4-microphone intensity probes. Using these probes it was possible to track the trajectory of the rocket ascent; the acoustically traced trajectory agrees well with the trajectory data obtained from Vandenberg. The measurements showed that the peak directivity of the launch vehicle noise was at 70.4±2.1 degrees relative to the plume direction. The total acoustic power level was found to be 197 dB re 1 pW. This represents an acoustic radiation efficiency of about 0.3%, somewhat lower than is normally assumed.