Accession Number : ADA301811

Title :   Sensitivity of Aircraft Runup/Community Noise Predictions to Excess Ground Attenuation.

Descriptive Note : Technical rept.,

Corporate Author : BOLT BERANEK AND NEWMAN INC CANOGA PARK CA

Personal Author(s) : Dunderdale, Thomas C.

PDF Url : ADA301811

Report Date : DEC 1977

Pagination or Media Count : 28

Abstract : This study examines the sensitivity of aircraft ground runup noise predictions to the accuracy of excess ground attenuation algorithm presently used in NOISEMAP. Day/Night Level (DNL) noise exposure contours were computed for one hour of single engine military power ground runup activity by F-4, C-l3l and C-S aircraft. These aircraft were chosen since they have straight jet, low bypass ratio fan, and high bypass ratio fan engines, propagation algorithms studied were: no excess ground attenuation, standard NOISEMAP excess attenuation, and NOISEMAP excess attenuation plus and minus one standard deviation of the field test data used to develop the present NOISEMAP algorithm. The results showed DNL 65 area changes of approximatelv +-4O percent for the straight jet, + 30 percent for the low bypass ratio fan jet, and up to 10 percent for the high bypass ratio fan jet due to + one standard deviation changes in the attenuation algorithm. Assuming no excess ground attenuation, the results showed the DNL 65 area increased approximately 100- for both the F-4 and C-141 type engines and 4% for the C-S type engines. This study clearly substantiates the need for further field measurements planned by AMRL in 1977 and 1978 to refine or modify the ground propagation algorithm and establish confidence in its accuracy.

Descriptors :   *NOISE POLLUTION, *AIRCRAFT NOISE, MATHEMATICAL MODELS, ALGORITHMS, COMMUNITIES, EXPOSURE(GENERAL), ACCURACY, MATHEMATICAL PREDICTION, WAVE PROPAGATION, ACOUSTIC MEASUREMENT, JET FIGHTERS, JET TRANSPORT AIRCRAFT, ACOUSTIC ATTENUATION, SOUND WAVES, RANGE(DISTANCE), AIRPORTS, RADIATED NOISE, AIRCRAFT ENGINE NOISE, HIGH BYPASS TURBOFANS, LOW BYPASS TURBOFANS.

Subject Categories : Acoustics
      Noise Pollution and Control
      Attack and Fighter Aircraft
      Transport Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE