1. Interview with C. Branson Smith. National Science Foundation, Washington, 14 Mar. 1974. Mr. Smith also loaned the author his work logs, notebooks, and other pertinent papers of the period Aug. 1953 to Aug. 1957.
2. C. Branson Smith, "Rocket Motors," TDM 1331, rev. 1. 31 July 1956, an internal document of Pratt & Whitney Aircraft Div. of United Aircraft.
3. C. B. Smith to P. W. Pratt, "Review of Our Position in the Rocket Propulsion Field," 10 July 1957, an intemal Pratt & Whitney document.
4. Minutes of 14 Nov. 1956 Meeting of the Fuels and Propulsion Panel of the USAF Scientific Advisory Board; excerpts declassified for the author by USAF.
5. Air Force response to Fuels and Propulsion Panel of the USAF Scientific Advisory Board regarding recommendations made at its 14 Nov. 1956 meeting, 6 Dec. 1957.
6. Perry W. Pratt to Commander, ARDC, 4 Mar. 1958. The author has not seen this source, but it is one of five references cited in a later, undated document, "Proposal for the Development of a Hydrogen-Oxygen Rocket Engine," PWA (preliminary). The references and attachments are dated from 4 Mar. 1958 to 18 July 1958; the undated proposal was probably written close to the latter date.
7. Interviews with: Col. Norman C. Appold (USAF ret.), Lockheed Georgia Co., Marietta, GA, 4 Jan. 1974; Col. John D. Seaberg (USAF ret.), Washington, 22 Aug. and 23 Nov. 1973; Col. Alfred J. Gardner (USAF ret.), Washington, 19 Sept. 1973; and Col. Jay R. Brill, Air Research and Development Command Hq., Andrews AFB, MD, 16 Jan. 1974. These men were the Suntan management team.
8. Interviews with Seaberg, 22 Aug. and 23 Nov. 1973, and Brill, 16 Jan. 1974. Both men recalled the letter and believed it to be in USAF files. Seaberg, now a civilian working for the Air Force, and Brill, on active duty and a Brigadier General, instituted separate searches within the USAF, including the Archives of the History Office, Hq. ARDC, but the key letter was not located.
9. Interview with Seaberg, 22 Aug, 1973; interview with Richard Horner, Washington, 13 Mar. 1974 (Horner did not recall the specific meeting but conceded that his reported action was reasonable and possible); interview by Schweibert of Col. N. C. Appold, Lt. Col. J. D. Seaberg, Maj. A. J. Gardner, and Capt. J. R. Brill, 9 Feb. 1959, released with portion excised by Air Force, 16 Sept. 1976; R. B. Canright to Monte D. Wright, NASA History Office, 1 Feb. 1976.
10. "Proposals for the Development of a Hydrogen-Oxygen Rocket Engine," PWA (preliminary) with specification no. 2208 attached and dated 18 July 1958.
11. Interview with Krafft Ehricke, Rockwell International, El Segundo, CA. 26 Apr. 1974.
12. Ibid.; Wemher von Braun to Monte D. Wright, NASA History Office, 29 Dec. 1975.
13. A. G. Negro, "Small High Energy Rocket Engines," PDM 57-45, 27 May 1957, and "Small High Energy Rocket for Satellite Vehicle," PDX1 57-132, 31 Oct. 1957, both internal documents of the Rocketdyne Div, of Rockwell International.
14. Statement of Krafft A. Ehricke. Advanced Studies. General Dynamics/ Astronautics, on 18 May 1962 before Subcommittee on Space Sciences of the Committee on Science and Astronautics, House of Representatives, 87th Congress, 2d sess., 15-18 May 1962.
15. "Minutes of Meeting (Amended) Informal Technical Advisory Committee for Propulsion, NASA-ARPA-ARDC, 7 August 1958," by A.O. Tischler, 20 Aug. 1958, Tischler's retired files.
16. "Minutes of Second Meeting (Amended) Informal Technical Advisory Committee for Propulsion: ASA-ARDC-ARPA-AOMC. 14 August 1958," by A. O. Tischler, 4 Sept. 1958, Tischler's retired files.
17. "Minutes of Third Meeting (Amended) Informal Technical Advisory Committee for pulsion: NASA-ARPA-USAF-AOMC, 28 Aug. 1958," by A.O. Tischler, 18 Sept. 1958, Tischler's retired files.
18. In interviews with Silverstein, Tischler, Cesaro, and Canright, the author attempted to verify whether the NASA meeting was the catalyst for action. Memories varied slightly, but there was general agreement between Silverstein, Tischler, and Canright. Cesaro neither confirmed nor denied this account, but said that the Centaur program started before the NACA-NASA got involved. While this is true, it does not rule out the competitive nature of the August 1958 meetings and actions. Interviews with Silverstein, Washington, 22 Nov. 1971, and Cleveland, 29 May 1974; Tischler, NASA, Washington, 25 June 1974; Canright, 7 Mar. 1974; and Cesaro, 12 Mar. 1974. In a letter to Monte D. Wright, NASA History Office, 1 Feb. 1976, Canright backed off somewhat, stating that ARPA orders generally took about a week to release after the technical staff defined the proper scope of work. He did not remember anything different about Order 19-59. J. D. Seaberg, in a letter to Wright, 29 Mar. 1976, pointed out the earlier negotiations between the Air Force and ARPA with Pratt & Whitney and General DynamicsAstronautics. Seaberg felt that the NASA meeting was a coincidence. None of these later comments negate the view that the NACA-NASA sponsored meeting spurred ARPA to faster action.
19. Lt. Col. John D. Seaberg, "USAF Participation in Project CENTAUR," 1962, copy to author by Seaberg.
20. A. O. Tischler, "Minutes of Fourth Meeting (Revised) Informal Technical Advisory Committee for Propulsion: NASA-USAF-AOMC, 11 Sept. 1958," 29 Sept. 1958, Tischler's retired files.
21. Tischler, "Minutes of Fifth Meeting (Revised) Technical Advisory Committee for Propulsion: NASA-ARPA-USAF-AOMC, 25 Sept. 1958," 15 Oct. 1958, Tischler's retired files.
22. Tischler's retired files; interview with Alfred M. Nelson, Bethesda, MD, 8 Mar. 1974. Nelson prepared the document on propellant selection data, 8 Oct. 1958; it bears WADC identification 58WCLP-8970: "Some Thoughts on the Next Decade of Space Exploration," 21 Nov. 1958. Reprinted as document II-4 of "Documents in the History of NASA: An Anthology," NASA History Office, 1975. NASA Administrator Glennan sent the document to Congress and to the President "on behalf of Drs. Hugh L. Dryden, Abe Silverstein, John Hagen, Homer Newell and myself."
23. Logbook of Cell 22, Rocket Laboratory, NACA Lewis Flight Propulsion Laboratory, Cleveland (files of Frank J. Kutina, NASA-Lewis); H. W. Douglass, G. Hennings, and H. G. Price, Jr., "Experimental Performance of Liquid Hydrogen and Liquid Fluorine in Regeneratively Cooled Rocket Engines," TM X-87 (NASA, 1959); William L. Jones, Carl A. Aukerman, and John W. Gibb, "Experimental Performance of a HydrogenFluorine Rocket Engine at Several Chamber Pressures and Exhaust-Nozzle Expansion Area Ratios," TM X-387 (NASA, 1960). For more on the simulated altitude testing technique, see Anthony Fortini, "Performance Investigation of a Nonpumping Rocket Ejector System for Altitude Simulation," TN D-257 (NASA, 1959); Joseph N. Sivo and Daniel J. Peters, "Comparison of Rocket Performance Using Exhaust Diffuser and Conventional Techniques for Altitude Simulation," TM X-100 (NASA, 1959).
24. Logbook of Rocket Test Facility (South 40), files of Frank J. Kutina, Lewis.
25. Edward A. Rothenberg, Franklin J. Kutina, Jr., and George R. Kinney, "Experimental Performance of Gaseous Hydrogen and Liquid Oxygen in Uncooled 20 000-Pound Thrust Rocket Engines," memo 4-8-59E (NASA, 1959).
26. William A. Tomazic, Edward R. Bartoo, and R. James Rollbuhler, "Experiments with Hydrogen and Oxygen in Regenerative Engines at Chamber Pressure from 100 to 300 Pounds per Square Inch Absolute," TM X-253 (NASA, 1960).
27. Sloop to Assoc. Dir., Lewis, "Accomplishments of Rocket Systems Branch in 1959," 8 Mar. 1960; work diary of C. Branson Smith, PWA, for a visit ca. 1957; interview with C. H. King, Jr., NASA, Washington, 18 Mar. 1974.
28. Seaberg, "USAF Participation in Project CENTAUR"; T. Keith Glennan, NASA Administrator, to Donald A. Quarles. Dep. Sec. of Defense, 6 May 1956, files of Abraham Hyatt, NASA History Office.
29. Abraham Hyatt, Asst. Dir. for Propulsion, to Glennan, "Centaur Project Management 21 May Arrangements, 21 1959; R. E. Horner to Herbert F. York, 10 June 1959; J. B. Macauley to R. E. Horner, 19 June 1959; Horner to York, 23 June 1959, all in files of Abraham Hyatt, NASA History Office.