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THE HIGH SPEED
FRONTIER
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- Chapter 4: The High-Speed
Propeller Program
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- FULL-SCALE PROPELLERS IN THE
16-FOOT HIGH-SPEED TUNNEL
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- [125] The primary
source of full-scale high-speed propeller data was the NACA
16-foot tunnel program on related 10-foot propellers....
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- [126] FIGURE 31.-The
2000-hp Propeller Dynamometer in the 16-Foot High-Speed
Tunnel.
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- ....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.
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- 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.
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- 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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