Mini RPV Engine Noise Reduction

Abstract

The purpose of this effort was to investigate the reduction in radiated acoustic noise associated with two types of engines considered for power plants in small (75-100 lb.) remotely piloted vehicles (Mini RPV) in the class of the Praeire and Calere Aircraft. The two engines considered are approximately 5 HP; the first a rotary combustion (RC), the second a two stroke cycle reciprocating (P). The sound pressure levels were recorded using a semicircle arrangement of microphones in a free field and with various engine noise reduction devices installed. The engines were rotated such that a spherical definition of the acoustic pressures were made. From these data the sound power levels and directional characteristics were determined. Aural detection analyses are performed for the most desirable noise reduction cases. The computed aural detection altitudes and the most significant sources of noise were defined.

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 1976
Accession Number
ADA027638

Entities

People

  • Davey L. Smith
  • Ralph M. Shimovetz

Organizations

  • Flight Dynamics Laboratory

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Absorption Coefficients
  • Acoustic Measurement
  • Acoustics
  • Aircrafts
  • Atmospheric Attenuation
  • Attenuation
  • Background Noise
  • Band Spectra
  • Combustion
  • Data Acquisition
  • Detection
  • Engine Mufflers
  • Engine Noise
  • Noise Reduction
  • Remotely Piloted Vehicles
  • Sound Pressure
  • Temperature Gradients

Readers

  • Acoustics.
  • Aerospace Engineering