From the Greenhouse into the Fighter Bomber: How ‘Metal Paper’ Became the World’s Thermal Insulator

Abstract

When the thermodynamicist Ernst Schmidt in Munich discovered aluminium foil’s properties as a thermal insulator in 1924, he first analysed it under both laboratory and product testing conditions at the polytechnic in Danzig (Gdańsk). The first findings that Schmidt gathered on aluminium foil, concerning its use as a thermal insulation material on a large scale, were gathered when the piping of Dresden’s municipal long-distance heating system was insulated with it. This application of aluminium foil as an insulating material affected energy efficiency in economic proportions for the first time. This contributed considerably towards the establishment of the professional discipline of thermal economics (Wärmewirtschaft) in Germany’s polytechnics at the end of the 1920s and later worldwide. When Schmidt was appointed director of the Institute for Engine Research at the Aeronautical Research Institute in Braunschweig in 1936, besides being involved in the development of liquid-propellant and solid-fuel rockets for military purposes, for the Wehrmacht and the Waffen-SS, he became increasingly occupied with the thermal insulation of those devices. Immediately after World War II, Schmidt was able to continue his research at Britain’s Royal Aircraft Establishment in Farnborough and later on at the universities in Braunschweig and Munich. His academic research particularly allowed him to continue to develop aluminium foils as insulation materials. This paper aims to retrace the path towards the exploration of aluminium foil as a thermal insulation material. It also shows how aluminium foil and its multifarious applications, more than other materials, emerged as a major economic factor in the twentieth century within the context of municipal and state energy economics. Civilian and military research projects that incorporated aluminium foil early on as a thermal insulator are also described.

Keywords:

• aluminium foil
• insulation
• materials science
• technical thermodynamics
• aircraft design
• rocketry
• jet engines
• turbines
• National Socialism

Acknowledgements

This paper was translated by Ann M. Hentschel, Stuttgart.

Notes

1. George E. Totten and D. Scott MacKenzie, ed., Handbook of Aluminium. Volume 1. Physical Metallurgy and Processes (New York: Marcel Dekker, 2003).

2. Catrin Kammer and Hans-Christof Wrigge, ‘Gewinnung von Aluminium (Bauxit),’ in Aluminium. 1. Grundlagen und Werkstoffe, ed. Catrin Kammer (Düsseldorf: Aluminium-Verlag, 2002), pp. 16–72.

3. Patent specification Gautschi & Jequier in Gontenswil (Switzerland). Verfahren zur Herstellung schmiegsamer Aluminiumfolie. Patentschrift Nr. 165965. 19 April 1905. Kaiserliches Patentamt.

4. Kelsey Hanlon and Hallie Forcinio, ed., Handbook of Package Engineering, 3rd edn (FL: CRC Press, 1998), pp. 99 ff.

5. Andreas Haka, Soziale Netzwerke im Maschinenbau an deutschen Hochschul- u. außeruniversitären Forschungseinrichtungen 1920–1970. Stuttgarter Beiträge zur Wissenschafts- und Technikgeschichte, ser. vol. 6 (Berlin: Logos Verlag, 2014), pp. 46ff.

6. Ernst Schmidt, ‘Wärmestrahlung technischer Oberflächen bei gewöhnlicher Temperatur’ (Habilitationsschrift, Munich, 1924).

7. Unpublished papers (= Nachlass, NL) of Prof. Dr. Ernst Schmidt (Historisches Archiv der Technischen Universität München [henceforth abbreviated as TUM.A.]: NL Ernst Schmidt, sequential no. B240, Wärmetechnik, Isoliermaterial, Erfindung der ALFOL [aluminum foil], E. Schmidt and E. Dyckerhoff).

8. Personnel file Rudolf Plank (Archiv des Karlsruher Institutes für Technologie): call number: 21011, 327.

9. Reichspatentamt (ed.) patent specs. no. 460419, 1925 (Deutsches Patentamt). Reichspatentamt (ed.), patent specs. no. 440 728, 1925 (Deutsches Patentamt).

10. TUM.A.: NL Ernst Schmidt, seq. no. B240, Wärmetechnik, Isoliermaterial, Erfindung der ALFOL [aluminum foil], E. Schmidt and E. Dyckerhoff).

11. Eidgenössisches Amt für geistiges Eigentum (ed.), no. 122135, 1927 (Deutsches Patentamt), Österreichisches Patentamt (ed.), patent specs. no. 1104 56, 1928 (Deutsches Patentamt), as well as notary list of ALFOL foreign patents dated 19 January 1928. (TUM.A.: NL Ernst Schmidt, seq. no. B241. Wärmetechnik. Isoliermaterial. Verbreitung der ALFOL. E. Schmidt and Dyckerhoff).

12. Correspondence between G. Schmaltz and Ernst Schmidt between April and June 1936 and between Ernst Schmidt and Fritz Kollmann (Ibid., seq. no. B221).

13. Hermann Schlichting and Klaus Gersten, Grenzschichttheorie, 10th edn (Berlin: Springer Verlag, 2006), p. 320.

14. Dieter Baehr and Karl Stephan, Wärme- und Stoffübertragung (Heidelberg: Springer, 2010), pp. 94f., p. 414; Ernst Schmidt, ‘Der Stand der Forschung auf dem Gebiete der Wärmeübertragung,’ Z-VDI, 76 (42) (1932), 1025–32.

15. John D. Anderson, ‘Ludwig Prandtl’s boundary layer,’ Physics Today, December 2005, p. 44; Helmuth Trischler, ‘“Big Science” or “Small Science”? Die Luftfahrtforschung im Nationalsozialismus,’ in: Geschichte der Kaiser-Wilhelm-Gesellschaft im Nationalsozialismus, ed. Doris Kaufmann. Bestandsaufnahme und Perspektiven der Forschung. 2 vols (Göttingen: Wallstein Verlag, 2000), pp. 328–62.

16. Correspondence between Ernst Schmidt and Ludwig Prandtl 1931 (Archiv der Max-Planck-Gesellschaft Berlin: 1st div. rep. 44, file 1400–1429.

17. Ernst Schmidt’s AL FOL-Berichte no. 3 dated 19 September 1927, as well as Bericht no. 7 dated 3 November and no. 8 dated 18 November 1927 (TUM.A.: NL Ernst Schmidt, B255. Alfol-Isolierungen Versuche).

18. Hans-Liudger Dienel, Die Thermodynamik der Ingenieure und die Physik, 1860–1920 (Munich: Max-Planck-Institut für Wissenschaftsgeschichte, 1996), pp. 35ff, Preprint 31.

19. Bernhard M. Gerbel, Kraft- und Wärmewirtschaft in der Industrie (Berlin: Springer, 1927).

20. Gerold Ambrosius, ‘Von Kriegswirtschaft zu Kriegswirtschaft 1914–1945,’ in Deutsche Wirtschaftsgeschichte. Ein Jahrtausend im Überblick, ed. Michael North (Munich: Verlag C.H. Beck, 2005), pp. 287–355.

21. Pfützner, Gedenkrede für Geheimen Regierungsrat Prof. Dr.-Ing. h.c. Rietschel. Gesundheitsingenieur, 44 (43, 44) (1921), pp. 541–4 and 549–50.

22. Hermann Rietschel, Leitfaden zum Berechnen und Entwerfen von Lüftungs- und Heizungsanlagen. 1 vol (Berlin: J. Springer, 1894).

23. Personalakte 141: Ludwig Wahl (1870–1945). Wiss. Archiv der Polyhymnia Dresden.

24. H. Schiemann, ‘Sitzungsbericht der Bezirksvereine,’ Z-VDI, 46 (1) (1902), 26–7, p. 27.

25. Letter from E. Dyckerhoff to E. Schmidt dated 10 March 1927 about drawing up the project for ALFOL insulation of Dresden’s long-distance heating works (TUM.A.: NL Ernst Schmidt, seq. no. B240).

26. Ernst Schmidt, 1955. Rückblick und Ergebnisse aus dem Forschungsheim für Wärmeschutz (Ibid., seq. no. 3571).

27. Ian Kershaw, Hitler. 1889–1936 (Stuttgart: Deutsche Verlags-Anstalt, 1998).

28. Correspondence between Ernst Schmidt and Wolfgang Schurig of the Kriegsmarine (Konstruktionsamt der Marine) incl. from April, June and August 1935 (TUM.A.: NL Ernst Schmidt, seq. no. B220).

29. Ernst Heinrich Hirschel, Horst Prem, and Gero Madelung, eds., Aeronautical Research in Germany. From Lilienthal until Today (Berlin: Springer, 2003), pp. 325–345.

30. Correspondence between Ernst Schmidt and Adolf Baeumker dated 10 September 1937 (TUM.A.: NL Ernst Schmidt, seq. no. 3614, Institut für Motorenforschung Braunschweig, Luftfahrtforschung).

31. Ralf Schabel, Die Illusion der Wunderwaffen. Düsenflugzeuge und Flugabwehrraketen in der Rüstungspolitik des Dritten Reiches (Munich: Oldenbourg, 1993), p. 98.

32. Bundesarchiv [formerly BDC]. Ernst Schmidt. Reichsforschungsrat. personnel file; Der Reichsmarschall des Großdeutschen Reiches. Präsident des Reichsforschungsrates. Der Bevollmächtigte für Strahlvortrieb. Prof. Dr. Ing. Ernst Schmidt. Letter from Ernst Schmidt to Albert Betz, AVA Göttingen dated 8 September 1943 (TUM.A.: NL Ernst Schmidt, seq. no. 3612); Haka, pp. 122ff.

33. Hariolf Grupp, Icíar Dominguez-Lacasa and Monika Friedrich-Nishio, Das deutsche Innovationssystem seit der Reichsgründung. Indikatoren einer nationalen Wissenschafts- und Technikgeschichte in unterschiedlichen Regierungs- und Gebietsstrukturen (Heidelberg: Physica-Verlag, 2002).

34. Record of a meeting at the conference on jet-pipe development, Arbeitstagung Strahlrohrentwickung on 9th and 10th of December 1944 at der LFA (TUM.A.: NL Ernst Schmidt, seq. no. 3600), on Peenemünde see: Tätigkeitsbericht by Otto Lutz, dated 13 May 1943 (Ibid., seq. no. 3596). An der TH Dresden bis zum Jahre 1945 durchgeführte wissenschaftliche Forschungsarbeiten, LFA to Walther Pauer (‘V2-Waffe’) (Universitätsarchiv der TU Dresden: Sig. 833, B 1.1 Rektorat 1945–68, Tätigkeit des Dolmetscherbüros 1946).

35. Correspondence between Ernst Schmidt and Olt. Dr. Wolf Trommsdorff or Major Dr. Götz von François (HWA) between 1943 and 1944 and Report by Ernst Schmidt from 1 November 1943 to 30 September 1944: Reisen und Besprechungen (TUM.A.: NL Ernst Schmidt, seq. no. 3612).

36. Haka, pp. 60ff.

37. Expert opinion by Adolph Nägel and Wilhelm Nusselt 1936 on the Institut für Motorenforschung at the DFL (TUM.A.: NL Ernst Schmidt, seq. no. 3614).

38. See Arbeitsberichte des Institutes für Motorenforschung der LFA of 1939, 1942–1943 (TUM.A.: NL Ernst Schmidt, seq. no. 3596).

39. Letter by Forschungsführung des Reichsluftfahrtministeriums dated 15 July 1944 (Ibid., seq. no. 3600).

40. Adam Tooze, Ökonomie der Zerstörung. Die Geschichte der Wirtschaft im Nationalsozialismus (Munich: Siedler-Verlag, 2008), pp. 561ff.

41. Tätigkeitsbericht zum Höhenprüfstand May 1944, correspondence between Ernst Schmidt and Wolf Trommsdorff from October 1943 until July 1944, Report by Ernst Schmidt for the Ministry of Supply dated 28 May 1948 (TUM.A.: NL Ernst Schmidt, seq. no. 3612).

42. See Bericht der Abteilung MU des Institutes für Motorenforschung for 1942 (Ibid., seq. no. 3596).

43. Account by Otto Föppl dated 12 July 1948 (Universitätsarchiv Braunschweig. TUBR: AI: 267, ‘Wöhler-Institut’ 1945–1949).

44. Arbeitsbericht des IMF der LFA for 1938 and 1943, commission by OKH Wa Prüf 6 from May and June 1943 (TUM. A.: NL Ernst Schmidt, seq. no. 3596, 3616, Institut für Motorenforschung Braunschweig).

45. See Arbeitsberichte des Institutes für Motorenforschung der LFA von 1939, 1942–1943 (Ibid., seq. no. 3596).

46. Andreas Haka, Wings of “Black Gold.” History of Fibre-Reinforced Materials,’ NTM. Journal of the History of Science, Technology and Medicine, 19 (1) (2011), pp. 76ff.

47. See Arbeitsbericht des Institutes für Motorenforschung of 1941 (1943 (TUM.A.: NL Ernst Schmidt, seq. no. 3596).

48. Entwicklungstagung vom 26. und 27. August 1944 in St. Aegyd am Neuwalde (Ibid., seq. no. 3600).

49. Haka, pp. 148ff.

50. Enclosure letter from SS-Obersturmführer Reischauer to Ernst Schmidt dated 2 September 1944 about the location of the outpost (TUM.A.: NL Ernst Schmidt, seq. no. 3600).

51. Bundesarchiv [formerly BDC], SSO, Neblich, Walter, 25.5.1895, Reichsführer-SS, SS personnel file.

52. Haka, pp. 148ff.

53. Letter from Ernst Schmidt to Hermann Göring dated 20 December 1944 (TUM. A.: NL Ernst Schmidt, seq. no. 3612), letter from Ernst Schmidt to Helmut Schelp dated 28 December 1944 (Ibid., seq. no. 3600).

54. Employment contracts (1958–1961) between Ernst Schmidt and the U.S. Navy Purchasing Office (Ibid., seq. no. 4082; research commission by U.S. Navy Purchasing Office, London [turbines]).

55. Information by Ernst Schmidt on the staffing form of the Military Government of Germany dated 6 November 1945 (Ibid., seq. no. 3776).

56. See correspondence between Ernst Schmidt and the ALFOL department of Dyckerhoff GmbH from 1956 (Ibid., seq. no. 3571).