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ReseaRch a n d developmenT In T h e aIR fo R c e 85
while engineers in the special projects branch examined the friction, oxidation,
and heating properties of alloy steel and ceramic bearings used in aircraft engines
and flight control assemblies. Meanwhile, the power plant laboratory operated
testing and calibration equipment to evaluate the operational performance of
aircraft engines produced by commercial manufacturers. Types ranged from
conventional piston engines to ramjets. In all cases, Aviation Week reported in
1953, “The [power plant] laboratory . . . reserves to itself the task of guiding and
evaluating the manufacturers’ development efforts and [the] solution of power
plant problems developing in field operations.” 52
Although it had been a center of power plant development and testing before
and during the war, the Wright Air Development Center was unable to fulfill
these functions as Air Force planners abandoned propeller-driven, reciprocating
engines in favor of much faster jet propulsion technologies. Consequently,
Wright ceded control of high-speed engine testing and evaluation to the Arnold
Engineering Development Center. 53 At this new facility in Tennessee—located
next to the town of Tullahoma, seventy-five miles southeast of Nashville—the
Air Force tested airframes, aircraft materials, and propulsion technologies
capable of operating at higher speeds, temperatures, and altitudes than their
wartime counterparts. “The emphasis on supersonic flight, guided missiles . . .
and electronic equipment has established requirements for a whole new set of
test facilities,” wrote General Craigie in March 1947. Beyond the sound barrier
(breached for the first time later that year), the air surrounding an airplane begins
to exhibit fluid-like characteristics. “The design of an aircraft that will fly in such
media,” Craigie predicted, “becomes quite an assignment.” 54 It was this and other
unknowns in aircraft performance that guided technical programming at the
Arnold Engineering Development Center during the 1950s.
The origins of the Tullahoma facility can be traced back to 1945, when Theodore
von Kármán and the Scientific Advisory Group conducted their survey of the
R&D laboratories that turned out jet engines, rocket motors, and other advanced
propulsion technologies for the German aircraft industry. Prompted by von
Kármán’s recommendation that similar R&D facilities should be built in the United
States, the AAF dismantled, shipped stateside, and reassembled at Tullahoma
the propulsion laboratory constructed by the Bayerischen Motoren Werke in
Munich in 1943 to develop jet engines for military aircraft. Also accompanying
the equipment were some of the German scientists who had operated it during the
52 A. McSurely, “WADC: $200-Million Research Key,” Aviation Week 59 (17 August 1953): 99, 102,
107–8 (quote on 108).
53 Putt, “Air Force Research and Development,” 42; Leggin, “Army Air Forces Research and
Development,” 2914. In 1948, the Wright Air Development Center’s largest wind tunnel operated at
a maximum sustained speed of 400 miles per hour, well below the speed necessary to break the sound
barrier. The power ratings of the tunnels at Wright did not exceed 40,000 horsepower. The wind tunnels
planned for the Air Engineering Development Division (later Arnold Engineering Development Center),
by contrast, were expected to operate at nearly four times that rating—150,000 horsepower. McLarren,
“Largest Aero Research Program,” 43; M. Dobert, “Home of the Impossible,” Flying 40 (March 1947): 34.
54 Craigie, “AAF Plans for Engineering and Research,” 20; Leggin, “Army Air Forces Research and
Development,” 2915.