The torsional and bending deflection of full-scale aluminum-alloy propeller blades under normal operating conditions

Hartman, Edwin P Biermann, David
naca-report-644
1938


The torsional deflection of the blades of three full-scale aluminum-alloy propellers operating under various loading conditions was measured by a light-beam method. Angular bending deflections were also obtained as an incidental part of the study. The deflection measurements showed that the usual present-day type of propeller blades twisted but a negligible amount under ordinary flight conditions. A maximum deflection of about 1/10 degree was found at a v/nd of 0.3 and a smaller deflection at higher values of v/nd for the station at 0.70 radius. These deflections are much smaller than would be expected from earlier tests, but the light-beam method is considered to be much more accurate than the direct-reading-transit method used in the previous test.

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