1. Telephone interviews with Harvey Hall, 31 Oct., 6 Nov. 1973; interview with Robert Gordon, Azusa, CA, 23 Apr. 1974.

2. Telephone inter-view of Abraham Hyatt by R. Cargill Hall, 21 Jan. 1970; interview with Hyatt, El Segundo, CA, 26 Apr. 1974; F. Zwicky, "Report on Certain Phases of War Research in Germany," Summary Report F-U-3RE, Hq., Air Materiel Command, Wright Field, Jan. 1947.

3. Beacon Desk, Identification Sect. Elect. Mat. Br., to Head, Special Weapons Sect., Elect. Mat. Br., Engineering Div., Bureau of Aeronautics, Navy Dept., Washington, by R. P. Haviland, 10 Aug. 1945, NASA History Office.

4. F. Zwicky et al., "Final Report as of December 31, 1944, to the Bur. of Aero., Navy Dept., on Contract NOa(s)-3055," Report R-50, Aerojet Engineering Corp., Pasadena, 31 Dec. 1944.

5. Interview with Gordon, 23 Apr. 1974.

6. George H. Osborn, Robert Gordon, and Herman L. Coplen, "Liquid Hydrogen Rocket Engine Development, 1944-1950," XXI International Astronautical Congress. Constance, West Germany, 9 Oct. 1970. Hydrogen research at Aerojet before 1945 has not been documented. Interview with George James, NSF, Washington, 19 July 1973.

7. Head, Special Weapons Sect. (R&E Elect. Mat. Br.) to Head, Experiments and Development Br., Bur. of Aero., Navy Dept., by J. A. Chambers, 25 Aug. 1945, NASA History Office; Dep. Dir. of Engineering (R&D) to Head, Experiments and Development Br., et al., Bur. of Aero., Navy Dept., by R. S. Hatcher, 30 Oct. 1945, NASA History Office; Minutes of 1st Meeting of Space Rocket Committee, 8 Oct. 1945, by Lt. (jg) Max, NASA History Office.

8. Minutes of 2d Meeting of Space Rocket Committee, 15 Oct. 1945, by Lt. (jg) Max, NASA History Office.

9. Minutes of 3d Meeting by Lt. (jg) Max, 22 Oct. 1945, with addendum by Harvey Hall. NASA History Office.

10. Minutes of Fourth Meeting, Space Rocket Committee, 29 Oct. 1945, by Lt. (jg) Max. NASA History Office.

11. O. E. Lancaster and J. R. Moore, "Investigation on the Possibility of Establishing a Space Ship in an Orbit above the Surface of the Earth," A.D.R. report R-48, Nov. 1945, Bur. of Aero., Navy Dept.

12. The JPL study, with all reports referenced, is summarized by H. J. Stewart, "A Summary of Performance Studies for a High Altitude Orbiting Missile," report 8-5, JPL-GALCIT, Pasadena, 10 July 1946.

13. F. J. Malina "and Martin Summerfield, "The Problem of Escape from the Earth by Rocket," Publication 5, JPL-GALCIT, Pasadena, 23 Aug. 1946. Malina and Summerfield presented a paper with same title at Sixth International Congress for Applied Mechanics (Sec. 11), Paris, 22-29 Sept. 1946; also Journal Aeronautical Sciences 14 (1947): 471-80.

14. Eugene M. Emme, Aeronautics and Astronautics: An American Chronology of Science and Technology in the Exploration of Space, 1915-1960 (Washington: NASA, 1961), P. 51.

15. R. Cargill Hall, "Earth Satellites, A First Look by the United States Navy in the 1940s," presented at XXI International Astronautics Congress, Constance, West Germany, 9 Oct. 1970.

16. As quoted by R. Cargill Hall, "Early U.S. Satellite Proposals," Technology and Culture 4 (Fall 1963): 411.

17. J. C. Hunsaker, "Jet Propulsion," an address before the National Academy of Sciences, 23 Apr. 1946, NASA History Office.

18. Cargill Hall, "Early U.S. Satellite Proposals," p. 414.

19. Excerpts from "Project RAND, First Quarterly Report," RA-15000, June 1946, NASA History Office.

20. "Preliminary Design of an Experimental World-Circling Spaceship," report SM-11827, Project RAND, Douglas Aircraft Co., Santa Monica, CA, 2 May 1946; "First Quarterly Report," RA-15000, Project RAND, Santa Monica, June 1946.

21. Cargill Hall, "Early U.S. Satellite Proposals," p. 423.

22. R. G. Wilson, "Structural Design Study-High Altitude Test Vehicle," report NA 46-758, North American Aviation, Inglewood, CA, 26 Sept. 1946.

23. "Second Quarterly Report," RA-15004, Project RAND, Santa Monica, Sept. 1946; Cargill Hall, "Early U.S. Satellite Proposals," pp. 22-23.

24. "Fourth Quarterly Report," RA-15033, Project RAND, Santa Monica, Mar. 1947.

25. "Contract NOa(s) -8496: Report of Progress during Period 27 September to 11 October 1946," Aerojet Engineering Corp., 17 Oct. 1946; Osborn, Gordon, and Coplen, "Hydrogen Rocket Engine."

26. Pedro C. Medina, "HATV-Summary Report," Engineering Report 2666, Glenn L. Martin Co., Baltimore, June 1947.

27. Robert Gordon, "Performance, Pressure Distribution. and Heat Transfer in a Water-Convection-Cooled Flared Tube Hydroxygen Motor of 400-lb Thrust," report RTM-34, 17 Mar. 1948.

28. "Contract NOa(s)-8496, Report of Progress during Period 27 Sept. to 11 Oct. 1946," Aerojet Engineering Corp., 17 Oct. 1946; "Report of Progress for the Month of May 1947, Contract NOa(s)-8496, Item 2," report R-78, Aerojet Engineering Corp., Azusa, 15 June 1947; and Robert Gordon, Herman L. Coplen, and David A. Young, "Final Report on Item 2, Contract NOa(s)-8496," report R-79, Aerojet Engineering Corp., Azusa, 15 July 1947.

29. R. Cargill Hall, "A Chronology of Some Events in Early United States Satellite Studies during the 1940s," JPL/HN-7, Jet Propulsion Laboratory, Pasadena, April 1970.

30. Cargill Hall, "Early U.S. Satellite Proposals," p. 427.

31. R. B. Canright, "The Relative Importance of Specific Impulse and Propellent Density for Large Rockets," report 4-29, Jet Propulsion Laboratory, Pasadena, 7 Jan. 1947. The von Braun, Hager, and Tschinkel report is a reference in Canright's report.

32. Under Contract NOa(s)-8496, Item 4 was the development of the rocket engine and Item 5 was the hydrogen liquefier. The Aerojet Engineering Corp. issued a variety of reports and memoranda. The following were used: "Progress for July 1947," R-80, 15 Aug. 1947; "Progress for Aug. 1947," R-81, 15 Sept. 1947; "Progress for Sept. 1947," R-83, 15 Oct. 1947; "Progress for Nov. 1947," R-85, 15 Dec. 1947; "Progress for Dec. 1947," R-87, 15 January 1948; "Semi-Annual Summary, 1 July-31 Dec. 1947," R-88, 30 Jan. 1948; "Progress for Jan. 1948," R-90, 15 Feb. 1948; "Quarterly Summary, Jan.-Mar. 1948," R-94, 30 Apr. 1948; "Semi-Annual Summary Report, 1 Jan.-30 June 1948," R-100, 20 Aug. 1948; "Quarterly Progress Report, 1 July-30 Sept. 1948," R-335, 13 Dec. 1948; "Semi-Annual Summary, 1 July-31 Dec. 1948," R-358, 25 Feb. 1949; George H. Osborn and Wayne D. Stinnett, "Development of a 3000-lb Thrust Liquid Hydrogen-Liquid Oxygen Rocket Motor," research technical memo. 54, 29 Aug. 1949; and David A. Young, "Research and Development of Hydrogen-Oxygen Rocket Engine, Model XLR 16-AJ-2, Final Report," R-397, 28 Sept. 1949. Other Aerojet reports are cited in Osborn, Gordon, and Coplen, "Hydrogen Rocket Development." These references are the sources for Aerojet technical results described in the remainder of the chapter.

33. Interview with Robert Gordon, 23 Apr. 1974.

34. Dwight I. Baker, "Regenerative Cooling Tests of Rocket Motors Using Liquid Hydrogen and Liquid Oxygen," report 4-53, Jet Propulsion Laboratory, Pasadena, 11 Aug. 1949.

35. Cargill Hall, "Early U.S. Satellite Proposals," p. 429.