Aeroacoustic Measurements of the Bell 699 Rotor on the Tiltrotor Test Rig in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel

Abstract

The Tiltrotor Test Rig (TTR) with the Bell 699 Rotor was tested in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel from 2017 to 2018. The primary goal of the test was to understand the operational capabilities of the TTR while also acquiring research data, including acoustic data. A data quality study revealed that the NFAC 40- by 80-Foot Wind Tunnel is an adequate acoustic environment to test the Bell 699 Rotor for helicopter, conversion, and airplane configurations. Representative acoustic data are presented, and selected acoustic data and corresponding test conditions are included