Rotor performance characteristics from an aeroacoustic helicopter wind-tunnel test program

Abstract : An investigation of helicopter rotor noise at model scale has been conducted in the Langley 4- by 7-Meter Tunnel. Two rotor systems were used in this program to examine the main-rotor-only noise characteristics in preparation for a complete main rotor/tail rotor interaction study. Each rotor system had several tip configurations in order to select at least one appropriate configuration to use for the main and tail rotor tests. The rotor systems were tested at various operating conditions particularly designed to evaluate the acoustic characteristics of each rotor/tip configuration. Both acoustic and aerodynamic data were acquired during this test; however, only aerodynamic data are presented herein. The acoustic data have been reported elsewhere and properly referenced within.