Accession Number : AD0695409

Title :   UNDERWATER SOUND SIGNATURES OF FLIGHT VEHICLES.

Descriptive Note : Status rept. no. 3,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK ORDNANCE RESEARCH LAB

Personal Author(s) : Baker,W. L. ; Macaluso,J. A.

Report Date : 20 SEP 1969

Pagination or Media Count : 31

Abstract : A report is given on the development of a model and the analytical procedures that will permit accurate calculations of the characteristics of the underwater sound field of flight vehicles operating over typical sea surfaces. A description is given of the design and verification of a general mathematical model and computational procedure that may be used to compute sound transmission through a 'rough' interface separating two fluids. Agreement between theory and experiment is good for the case of sound transmitted from a loudspeaker source in air through several types of stationary corrugated boundary surfaces to an underwater receiver. The theory appears inaccurate, as expacted, when applied to surfaces of very steep slope (i.e., greater than that expected in ocean waves) or when applied in situations wherein the acoustic wavelength in either medium is large with respect to the principal physical features of the surface. A description is also given of a model helicopter rotor designed to provide laboratory data on the behavior of actuator discs near rigid or semirigid (water) boundaries. (Author)

Descriptors :   (*AIRCRAFT NOISE, UNDERWATER), ACOUSTIC SIGNALS, UNDERWATER SOUND, MATHEMATICAL MODELS, WATER WAVES, SOUND TRANSMISSION, HELICOPTER ROTORS

Subject Categories : Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE