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THE HIGH SPEED
FRONTIER
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- Chapter 3
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- Transonic Wind Tunnel
Development (1940 -1950)
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- [61] In 1940 the
so-called "Transonic Barrier" was perceived primarily as a set of
adverse and uncertain aerodynamic effects including an
order-of-magnitude increase in drag coefficient, severe and
perhaps catastrophic buffeting, and abrupt changes in the
stability and control characteristics of the airplane. There was
no realistic possibility that the piston engine-propeller system
could ever be developed to produce the enormous powers required
for transonic flight, and in reality this was a more
substantial component of the "barrier" than the unknown
aerodynamics. The third major element of the problem was the
failure of the classical tools of aircraft development to function
at transonic speeds; conventional wind tunnels appeared to be
useless in the Mach number range from about 0.8 to 1.2, and flight
testing of military aircraft beyond about 350 mph could be
accomplished only by dives, which were extremely hazardous and in
any case could not exceed about Mach 0.8, the terminal speed in
vertical dives for typical 1940 drag-weight ratios.
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- We have already mentioned the advent of
the jet engines pioneered by the British and Germans, which
eliminated the propulsion barrier. The remaining aerodynamic and
facility "barriers" were dispelled by NACA programs of the forties
in one of the most effective team efforts in the annals of
aeronautics. These NACA achievements were recognized twice by
aviation's highest award, the Collier Trophy. The first award, for
the achievement of supersonic flight by the X-1, was presented in
1948 jointly to John Stack for the NACA contributions, to Lawrence
D. Ben the manufacturer, and to Charles E. Yeager the USAF pilot.
The second award, for the slotted transonic tunnel development,
was presented in 1952 to John Stack and Associates.
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- A few weeks before the second award was
presented to him by President Harry S. Truman on December 17,
1952, Stack appeared [61] unexpectedly
in my office in a state of considerable agitation. He had just
received notice of the award from J. F. Victory, chairman of the
committee for the Collier Trophy. Stack said he was reluctant to
accept the award as the sole recipient because so many others at
Langley had contributed importantly. He wondered how the others
would react. I believed they would feel as I did that he richly
deserved this recognition. Without his aggressive leadership and
promotional efforts there would have been no large transonic
tunnels at Langley at that time. But Stack was insistent that the
other principals should be included and we worked up a list of
some 19 names. After negotiation, the Trophy Committee agreed to
make the citation read, "to John Stack and Associates," but not to
name the associates as Stack had desired. To a degree, however, he
had the last word by issuing a press release at the time of the
award which included the names of the others and a brief
indication of their contributions (ref. 78). Stack also helped organize a recognition dinner
sponsored by local businessmen on January 17, 1953, at which he
introduced his associates.
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- Although the primary concern in this
chapter will be the events leading to the achievements of the
transonic wind tunnels, we will also
necessarily be dealing with the
development of new transonic flight techniques. In a sense, the
flight approaches were also transonic research "facilities." Of
particular interest are a number of strong interactions between
the flight and ground developments which influenced the course of
events.
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