Acoustic Microphone Traverse 14-by 22-Foot Subsonic Tunnel

Developed in the late 1960's, the NASA Langley Research Center's 14-by-22-Foot Subsonic Tunnel was not originally conceived to test and evaluate the aeroacoustic characteristics of flight vehicles. However, sometime after the tunnel's inception, a need to do so developed. To facilitate acoustic measurements, a removable microphone traverse was designed and built. The implemented solution was functional yet time consuming to install and remove. Comprised of numerous interlocking parts, each installation of the system required three weeks of non-productive tunnel time, numerous personnel, and specialized equipment. A recently renewed focus on aeroacoustic testing brought about a desire to improve the operational efficiency of this type of testing in the 14-by 22-Foot Subsonic Tunnel. Specifically, a goal was established to reduce non-productive installation time from three weeks to just three shifts. In addition, no specialized equipment was to be required for installation and removal. Meeting these goals required the development of a new microphone traverse system. This presentation will provide details of the newly designed, built and commissioned traverse which meets the stated objectives.