Accession Number:

ADA801336

Title:

Comparison of Sound Emission from Two-Blade, Four-Blade, and Seven-Blade Propellers

Descriptive Note:

Technical note

Corporate Author:

NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS LANGLEY FIELD VA LANGLEY AERONAUTICAL LABORATORY

Personal Author(s):

• Hicks, Chester W.
• Hubbard, Harvey H.

Report Date:

1947-07-01

Pagination or Media Count:

41.0

Abstract:

Appreciable sound-pressure reduction may be realized by changing from two blades to seven blades for comparable operating conditions. Small reduction in intensity may be realized by increasing propeller diameter for same tip speed and power absorbed. AT fixed pitch setting, sound-intensity levels expressed in decibels are approximately a linear function of tip speed for test Mach number range for all propellers tested. For same tip speed and power absorbed, seven blades are only slightly less loud than two blades at distances greater than 400 ft even though difference in sound pressure is large.

Descriptors:

• *PROPELLER BLADES
• *AERIAL PROPELLERS
• DIAMETERS
• PITCH(INCLINATION)
• COMPARISON
• MACH NUMBER
• SOUND PRESSURE
• FUNCTIONS(MATHEMATICS)
• EMISSION
• TEST AND EVALUATION
• LINEARITY

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE