Pilot Zak Johns checks out a hexacopter before its flight over the acoustics array (in foreground). (NASA/David C. Bowman)

Microphones strung together on an unmanned aircraft system runway were used to record the sounds of remotely piloted aircraft flying overhead as part of a NASA project to measure full-scale aircraft noise. The work is part of research to reduce airplane noise and make the skies more environmentally friendly, especially around airports.

To assess the performance of the array in real-world outdoor conditions, researchers used a variety of small, unmanned aircraft — from vertical take off and landing (VTOL), six-rotor hexacopters to remotely piloted jets. Researchers will use the data to improve computer noise models of small vertical lift aircraft — an area of research that may be especially critical as UAS use becomes more common.

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