Some far-field acoustics characteristics of the XV-15 tilt-rotor aircraftFar-field acoustics tests have been conducted on an instrumented XV-15 tilt-rotor aircraft. The purpose of these acoustic measurements was to create an encompassing, high confidence (90 percent), and accurate (-1.4/ +1/8 dB theoretical confidence interval) far-field acoustics data base to validate ROTONET and other current rotorcraft noise prediction computer codes. This paper describes the flight techniques used, with emphasis on the care taken to obtain high-quality far-field acoustic data. The quality and extensiveness of the data base collected are shown by presentation of ground acoustic contours for level flyovers for the airplane flight mode and for several forward velocities and nacelle tilts for the transition mode and helicopter flight mode. Acoustic pressure time-histories and fully analyzed ensemble averaged far-field data results (spectra) are shown for each of the ground contour cases.
Document ID
19910027861
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Golub, Robert A. (NASA Langley Research Center Hampton, VA, United States)
Conner, David A. (NASA Langley Research Center Hampton, VA, United States)
Becker, Lawrence E. (NASA Langley Research Center Hampton, VA, United States)
Rutledge, C. Kendall (NASA Langley Research Center Hampton, VA, United States)
Smith, Rita A. (Lockheed Engineering and Sciences Co. Hampton, VA, United States)