AIRFRAME NOISE OF THE DC-9-31

Airframe noise measurements are reported for the DC-9-31 aircraft flown at several speeds and with a number of flap, landing gear, and slat extension configurations. The data are corrected for wind effects, atmospheric attenuation, and spherical divergence, and are normalized to a 1 meter acoustic range. The sound pressure levels are found to vary approximately as the fifth power of flight velocity. Both lift and drag dipoles exist as a significant part of the airframe noise. The sideline data imply that a significant side-force dipole exists only for the flap- and gear-down configurations; for others, the data imply the existence of only the lift and drag dipoles. The data are compared with airframe noise predictions using the drag element and the data analysis methods. Although some of the predictions are good, further work is needed to refine the methods, particularly for the flap- and gear-down configurations.

  • Corporate Authors:

    Douglas Aircraft Company, Incorporated

    3855 Lakewood Boulevard
    Long Beach, CA  United States  90801
  • Authors:
    • Bauer, A B
    • Munson, A G
  • Publication Date: 1978-7

Media Info

  • Pagination: 54 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00185779
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: NASA-CR-3027 Final Rpt.
  • Contract Numbers: NAS1-14696
  • Files: TRIS
  • Created Date: Dec 29 1979 12:00AM