Jakob Ackeret

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Jakob Ackeret (born March 17, 1898 in Zurich ; † March 27, 1981 in Küsnacht ) was a Swiss aerodynamicist .


Jakob Ackeret was born in Zurich in 1898 as the son of a master locksmith. After taking the high school diploma in 1916, he enrolled in mechanical engineering at the ETH Zurich in October of the same year . After graduating in March 1920, he took up a position as assistant for caloric machines at Aurel Stodola on October 1, 1920 . In the autumn of 1921 Ackeret went to Ludwig Prandtl in Göttingen. The study visit, originally planned for one year, lasted until 1927. In Göttingen, he mainly worked in the field of aircraft aerodynamics, with a particular interest in the problems of high-speed flight. In the years 1925–1926 he headed the expansion of the newly founded Kaiser Wilhelm Institute for Flow Research . Ackeret returned to Switzerland in 1927 and took up the position of chief hydraulic engineer at Escher Wyss AG in Zurich. In 1928 he completed his habilitation with the paper About air forces at very high speeds, especially in flat currents, and was appointed as a private lecturer at the ETH Zurich. In his habilitation thesis he suggests the concept of the Mach number . In 1931 he was appointed associate professor and finally in 1934 full professor and head of the Institute for Aerodynamics at the ETH Zurich, a position he held until his retirement in 1967.

Scientific achievements

Jakob Ackeret's main area of ​​work was fluid dynamics . Important theoretical foundations originate from him, the applications of which in mechanical engineering and aviation he promoted. He was also interested in other problems such as cavitation in water turbines, wind pressure on buildings and the ventilation of tunnels.

The aerodynamic investigation methods he introduced are an important means of improving steam and gas turbines . They were also used in the investigation of the Tacoma Bridge collapse (1940).

His most important work includes research on supersonic flight . During his time in Göttingen, in 1925, he applied the linearized theory, which is now named after him, to supersonic flows on profiles with sharp leading and trailing edges. In his contribution to the handbook of physics , supersonic flows are treated for the first time.

Ackeret developed a variable-pitch propeller for ships, the further development of which was later also used in aircraft such as the Swiss C-36 fighter aircraft and Morane D-3802/03.

Together with Curt Keller from the research department at Escher Wyss, he developed a closed aerodynamic steam turbine, the so-called AK system.

Under the direction of Ackeret, a subsonic and a supersonic wind tunnel were built at the Institute for Aerodynamics . The investigations carried out in the wind tunnel are of great interest to the Swiss military and the aircraft industry. The supersonic wind tunnel was recreated in Italy in 1935.


Memorial plaque for Jakob Ackeret and other scientists at the DLR entrance, Göttingen, Bunsenstrasse 10

The Swiss Association for Aviation Sciences has awarded the Jakob Ackeret Prize since 2006.


Manuscripts and autographs from the ETH Library


  • Festschrift Jakob Ackeret. For his 60th birthday on March 17, 1958. Journal for Applied Mathematics and Physics (ZAMP). Vol. IXb, no. 5-6, pp. 9-25, Basel 1958, ISSN  0044-2275
  • Georges Bridel: Jakob Ackeret. In: Swiss Pioneers of Economy and Technology Vol. 67, Association for Economic History Studies, Meilen 1998, pp. 73–92.
  • Fritz Dubs: Nekrolog Jakob Ackeret. In: Swiss engineer and architect. 30-31, 1981, pp. 679-680
  • Thomas Fuchs: Ackeret, Jakob. In: Historical Lexicon of Switzerland .
  • N. Rott: Jakob Ackeret and the history of the Mach number. In: Annual Review of Fluid Mechanics Vol. 17, 1985, pp. 1-9.
  • Fritz Schultz-Grunow: J. Ackeret: Personal memories. In: Swiss engineer and architect. Volume 21, 1983, pp. 587-594

Web links

Individual evidence

  1. Jakob Ackeret: About cavitation in water turbines. In: Escher-Wyss Mitteilungen. Volume 1, 1928, pp. 40-45
  2. Jakob Ackeret: Wind pressure studies on a gas container model. In: Escher-Wyss Mitteilungen. Volume 7, 1934, pp. 124-129
  3. Jakob Ackeret: The wind pressure on chimneys with a circular cross-section. In: Schweizer Bauzeitung. Volume 108, 1936, p. 25
  4. Jakob Ackeret, F. Stüssi: On the collapse of the Tacoma suspension bridge. In: Schweizerische Bauzeitung. Volume 117, 1941, pp. 137-140
  5. Jakob Ackeret: Air forces on wings that are moved with greater than the speed of sound In: Zeitschrift für Flugtechnik. Vol. 16, 1925, pp. 72-74
  6. Jakob Ackeret: Gas dynamics. In: Handbook of Physics. , Vol. VII, Chap. 5, pp. 289–342, Springer Verlag, Berlin 1927
  7. Jakob Ackeret: controllable pitch propellers for ships. In: Escher-Wyss Mitteilungen. Volume 8, 1935, pp. 63-67
  8. ^ The Swiss variable pitch propeller for aircraft. In: Neue Zürcher Zeitung. Technical supplement, November 5, 1941
  9. Jakob Ackeret, Curt Keller: Aerodynamic heat engine with closed circuit. In: Journal of the Association of German Engineers. Volume 85, 1941, pp. 491-500
  10. Jakob Ackeret: Report on the activities and development of the Institute for Aerodynamics ETH, in 1934. (Online) ( Memento of the original from June 11, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (pdf, 1 MB) @1@ 2Template: Webachiv / IABot / www.ethbib.ethz.ch
  11. Jakob Ackeret: Report on the activity and development of the Institute for Aerodynamics ETH, in 1935.
  12. Jakob Ackeret: Gallerie aerodinamiche per old velocita. Relazione presentata al V Convegno Volta su le alte velocita in aviazione, Roma 1935, In: L'Aerotecnica. Volume 16, 1936, pp. 885-925