Ground-based Acoustic Measurements of Small Multirotor Aircraft

Experimental procedures are developed for the measurement and characterization of noise from small multirotor aircraft. These procedures are applied to measure the noise of the Tarot X8. The acoustic characteristics of the Tarot X8 are evaluated for a number of level flight flyover conditions. Both tonal and broadband noise is found to be significant, but the relative importance depends on the angle of observation. Variability in noise is assessed both across repeated runs of the same condition and within a run using an array of microphones parallel to the flight track. Variability is found to increase as the distance between the microphone and aircraft increases. Variations within a run are significant (on the order of 2 dBA), but do not explain the greater variation (on the order of 5 dBA) in levels between runs.