THE HIGH SPEED FRONTIER
 
 
Chapter 4: The High-Speed Propeller Program
 
FULL-SCALE PROPELLERS IN THE 16-FOOT HIGH-SPEED TUNNEL
 
 
 
[125] The primary source of full-scale high-speed propeller data was the NACA 16-foot tunnel program on related 10-foot propellers....
 

photo of propeller dynamometer
 
[126] FIGURE 31.-The 2000-hp Propeller Dynamometer in the 16-Foot High-Speed Tunnel.
 
....conducted from 1945 to 1958. This was the program which had started to take shape in the thirties but had been long delayed pending the design and procurement of the 16-foot high-speed tunnel and the 2000-hp dynamometer. The staff of 16-foot comprised ex-PRT engineers almost exclusively, and most of them retained the conservative, practical attitudes toward propeller research which had characterized the PRT managements of Donald Woods and David Biermann. When I arrived at 16-foot in the summer of 1943, I soon learned that the staff regarded the emergency propeller program with its 4-foot "model" propellers in the 8-foot tunnel with considerable skepticism; the meaningful data would come later from the full-scale tests in 16-foot, conducted by men who understood propellers. None of us realized then that the 8-foot tunnel high-speed program would skim much of the cream, so to speak, leaving the 16-foot force-test programs of the forties to supply data which in most cases differed only in detail from the so-called "model" propeller tests.
 
The propeller program at 16-foot was supervised by B. W. Corson, Jr., a studious researcher who made many personal contributions, both analytical [127] and inventive, in addition to his management activities. With only one or two exceptions, his colleagues were engineers and experimentalists. J. D. Maynard, a meticulous hard-working senior member of the staff, is credited with contributions to the dynamometer development in addition to the prolific production of precision propeller data evidenced by his publications.
 
Following shake-down testing and several important modifications and improvements, the 2000-hp dynamometer (fig. 31) began producing useful data in 1945 (ref. 143). It measured directly the thrust and torque of propeller plus spinner. Deducting the spinner forces yielded the characteristics; of the propeller itself, free from the body-drag changes included in the "propulsive" characteristics determined in the 8-foot tunnel tests. The close agreement for most operating conditions between the 10-foot propeller data and much of the 4-foot "propulsive" data implies that both the scale effects and the propeller/nacelle interference effects were small. By mid-1948, the systematic force testing of the related 10-foot propellers on the 2000-hp dynamometer had been completed (refs. 144, 145, 146).
 

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