<strong>Facing</strong> <strong>the</strong> <strong>Heat</strong> <strong>Barrier</strong>: A <strong>History</strong> of Hypersonics values using <strong>the</strong>ories that include only free-stream flow and ignore <strong>the</strong> boundary layer. This emphasized anew <strong>the</strong> importance of <strong>the</strong> boundary layer in producing hypersonic skin friction. 52 These results were fundamental, both for aerodynamics and for wind-tunnel design. With <strong>the</strong>m, <strong>the</strong> 11-inch tunnel entered into a brilliant career. It had been built as a pilot facility, to lay groundwork for a much larger hypersonic tunnel that could sustain continuous flows. This installation, <strong>the</strong> Continuous Flow Hypersonic Tunnel (CFHT), indeed was built. Entering service in 1962, it had a 31-inch test section and produced flows at Mach 10. 53 Still, it took a long time for this big tunnel to come on line, and all through <strong>the</strong> 1950s <strong>the</strong> 11-inch facility continued to grow in importance. At its peak, in 1961, it conducted more than 2,500 test runs, for an average of 10 per working day. It remained in use until 1972. 54 It set <strong>the</strong> pace with its use of <strong>the</strong> blowdown principle, which eliminated <strong>the</strong> need for costly continuous-flow compressors. Its run times proved to be adequate, and <strong>the</strong> CFHT found itself hard-pressed to offer much that was new. It had been built for continuous operation but found itself used in a blowdown mode most of <strong>the</strong> time. Becker wrote that his 11-inch installation “far exceeded” <strong>the</strong> CFHT “in both <strong>the</strong> importance and quality of its research output.” He described it as “<strong>the</strong> only ‘pilot tunnel’ in NACA history to become a major research facility in its own right.” 55 Yet while <strong>the</strong> work of this wind tunnel was fundamental to <strong>the</strong> development of hypersonics, in 1950 <strong>the</strong> field of hypersonics was not fundamental to anything in particular. Plenty of people expected that America in time would build missiles and aircraft for flight at such speeds, but in that year no one was doing so. This soon changed, and <strong>the</strong> key year was 1954. In that year <strong>the</strong> Air Force embraced <strong>the</strong> X-15, a hypersonic airplane for which studies in <strong>the</strong> 11-inch tunnel proved to be essential. Also in that year, advances in <strong>the</strong> apparently unrelated field of nuclear weaponry brought swift and emphatic approval for <strong>the</strong> development of <strong>the</strong> ICBM. With this, hypersonics vaulted to <strong>the</strong> forefront of national priority. 20 First Steps in Hypersonic Research 1 Anderson, <strong>History</strong>, pp. 251-255. 2 Wegener, Peenemunde, pp. 23-24, 167; Von Karman and Edson, Wind, p. 221. 3 Wegener, Peenemunde, pp. 22-23; Neufeld, Rocket, pp. 87-88. 4 Neufeld, Rocket, p. 87. 5 Wegener, Peenemunde, pp. 24-25; Shapiro, Compressible, pp. 203-04. 6 See, for example, Miller and Durant, Worlds, pp. 9, 17, 23. 7 Neufeld, Rocket, pp. 86, 88-91 (quote, p. 89). Zeppelin: Wattendorf, German, p. 19. 8 Wegener, Peenemunde, photos following p. 84. 9 Von Karman and Edson, Wind, pp. 218-19. 10 Dornberger, V-2, pp. 122-23, 127-28. 11 Hallion, Hypersonic, pp. xvi, xviii; Neufeld, Rocket, pp. 248-50, 283. 12 Neufeld, Rocket, pp. 250-51; Dornberger, V-2, p. 268. 13 Neufeld, Rocket, p. 250. 14 NASA SP-4303, pp. 77, 316, 330. 15 Wegener, Peenemunde, p. 70. 16 Lukasiewicz, Experimental, pp. 71-76. 17 Wegener, Peenemunde, pp. 70-71. 18 Neufeld, Rocket, p. 87; Wegener, Peenemunde, p. 24; Wattendorf, German, p. 4. 19 Wegener, Peenemunde, pp. 32, 75, photos following p. 84. 20 Wattendorf, German, p. 4. 21 Spaceflight, May 1973, pp. 166-71 (quotes, pp. 168, 170); Huxley, Brave, pp. 58, 59, 61. 22 Spaceflight, May 1973, pp. 166, 171-72 (quote, p. 166); Ley, Rockets, pp. 533-537. 23 Spaceflight, May 1973, pp. 171-72, 175-76; Ley, Rockets, pp. 533-34, 535; Ordway and Sharpe, Rocket Team, pp. 327-28. 24 Spaceflight, May 1973, pp. 168-69. 25 Ley, Rockets, pp. 514-19, 524; Allen and Polmar, Downfall, pp. 103, 226. 26 Ordway and Sharpe, Rocket Team, p. 329; Jenkins, Space Shuttle, p. 2. 27 “Sänger.” MBB brochure, August 1986. 28 Boyne, Arrow, p. 139. 29 Speer, Inside, pp. 364-66. 30 Anderson, <strong>History</strong>, p. 435; NASA: SP-440, pp. 51-52; SP-4305, p. 467. 31 NASA: SP-440, p. 52; SP-4302, pp. 63-64. 32 AIAA Paper 79-0219, pp. 3-4. 33 Journal of <strong>the</strong> Aeronautical Sciences, July 1947. pp. 373-409 (Stack quote, p. 406). 34 Hermann, “Supersonic,” p. 439; Anspacher et al., Legacy, pp. 209-10. 35 Becker: Professional resume; NASA SP-4305, p. 54. R-2800 engine: “Dependable Engines” (Pratt & Whitney). 21
<strong>Facing</strong> <strong>the</strong> <strong>Heat</strong> <strong>Barrier</strong>: A <strong>History</strong> of Hypersonics 36 Memo, Becker to Chief of Research, 3 August 1945 (includes quotes); see also NASA SP-4305, pp. 344-346. 37 John Becker interview by Walter Bonney, March 1973 (quotes, p. 4). NACA budget: NASA SP-4305, p. 428. Project approval noted in memo, Becker to Stack, 16 January 1946. 38 Memo, Becker to Stack, 16 January 1946 (includes quotes). 39 Journal of Applied Physics, July 1950, pp. 619-21; NACA TN 3302. Air heater: NASA SP-4305, p. 471. 40 Becker, memo for record, 23 January 1948. 41 AIAA Paper 88-0230, p. 6. 42 NACA TN 2171, p. 3. 43 Ibid., pp. 6, 21 (quotes, pp. 1, 19). 44 NACA TN 2223 (quote, p. 11); AIAA Paper 88-0230, pp. 6-7. 45 Shapiro, Compressible, pp. 59-68. Photos by Mach and Meyer: Anderson, <strong>History</strong>, pp. 376, 382. 46 Shapiro, Compressible, table, p. 620. 47 Journal of Applied Physics, July 1950, pp. 619-28 (quote, p. 621). 48 Ibid. (quote, p. 622). 49 230,000 feet: Shapiro, Compressible, table, pp. 612-13. Mach 13.8: calculated from Shapiro, Compressible, eq. 4.14b, p. 83. 50 NACA RM L51J09 (quotes, p. 19). 51 NACA RM L51D17; Journal of <strong>the</strong> Aeronautical Sciences, October 1951, pp. 641-48 (quote, p. 648). 52 NACA TN 2773. 53 AIAA Paper 88-0230, pp. 8-9; NACA: SP-440, pp. 94-95; TM X-1130, p. 27. 54 AIAA Paper 88-0230, p. 7. 55 Becker, handwritten notes, January 1989 (includes quotes); NASA: SP-4305, p. 471; RP-1132, p. 256. 22