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Investigation of the NACA 4-(3)(8)-045 Two-blade Propellers at Forward Mach Numbers to 0.725 to Determine the Effects of Compressibility and Solidity on PerformanceAs part of a general investigation of propellers at high forward speeds, tests of two 2-blade propellers having the NACA 4-(3)(8)-03 and NACA 4-(3)(8)-45 blade designs have been made in the Langley 8-foot high-speed tunnel through a range of blade angle from 20 degrees to 60 degrees for forward Mach numbers from 0.165 to 0.725 to establish in detail the changes in propeller characteristics due to compressibility effects. These propellers differed primarily only in blade solidity, one propeller having 50 percent and more solidity than the other. Serious losses in propeller efficiency were found as the propeller tip Mach number exceeded 0.91, irrespective of forward speed or blade angle. The magnitude of the efficiency losses varied from 9 percent to 22 percent per 0.1 increase in tip Mach number above the critical value. The range of advance ratio for peak efficiency decreased markedly with increase of forward speed. The general form of the changes in thrust and power coefficients was found to be similar to the changes in airfoil lift coefficient with changes in Mach number. Efficiency losses due to compressibility effects decreased with increase of blade width. The results indicated that the high level of propeller efficiency obtained at low speeds could be maintained to forward sea-level speeds exceeding 500 miles per hour.
Document ID
19930092056
Acquisition Source
Legacy CDMS
Document Type
Other - NACA Technical Report
Authors
Stack, John (National Advisory Committee for Aeronautics. Langley Aeronautical Lab. Langley Field, VA, United States)
Draley, Eugene C (National Advisory Committee for Aeronautics. Langley Aeronautical Lab. Langley Field, VA, United States)
Delano, James B (National Advisory Committee for Aeronautics. Langley Aeronautical Lab. Langley Field, VA, United States)
Feldman, Lewis (National Advisory Committee for Aeronautics. Langley Aeronautical Lab. Langley Field, VA, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1950
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
NACA-TR-999
Accession Number
93R21346
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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