German Wind Power Museum Adds Voith Blade from the Early 80s

By Paul Gipe

Arne Jaeger reports that the Deutsches Windkraftmuseum (the German Wind Power Museum) has obtained one of the two blades used on the Voith 520 wind turbine developed in Germany during the late 1970s and tested in the early 1980s.

The turbine followed Ulrich Hütter’s design aesthetic by using a downwind, two-blade teetered rotor. The 52-meter diameter Hütter-Voith experimental turbine was more than twice the size of Hütter’s StGW-34 (2,100 m² vs 908 m²) and was one of the giants of its day.

For comparison, the Hütter-Voith 520 was only slightly smaller than Tvind’s 54 meter diameter turbine of 1978 that was designed to be larger than the famed 53.4-meter diameter Smith-Putnam turbine of 1941.

In a novel departure for Hütter, the Voith 520 brought mechanical power down to ground level where it was used to drive a vertically-mounted generator. This was similar to the transmission concept used by Dimitri Stein’s Norwind on the island of Neuwerk in the North Sea that Hütter was familiar with.[1]

Like Hütter’s other prototypes, the Voith 520 was tested at the University of Stüttgart’s test field near Stötten-Schnittlingen in the Schwabian Alps.

And like Hütter’s other designs, the turbine operated at a very tip speed, 100 m/s, and a very high tip-speed ratio of nearly 12. Other wind turbines of the period operated at 40-70 m/s with tip-speed ratios of 5-7.

Further reflecting Hütter’s philosophy that wind turbines should be designed for low to moderate winds, the Voith 520 was rated at only 270 kW in a wind speed of 8.5 m/s, thus giving the wind turbine a specific area of nearly 8 m²/kW. This result was comparable to his Allgaier design (10 m²/kW) of the early 1950s and his StWG-34 (9.1 m²/kW) of the late 1950s. Wind turbines with such high specific areas were not seen again until the 2010s.

The blades were built by aerospace giant MBB (Messerschmidtt-Bölkow-Blohm) in München out of carbon fiber. However, during hard braking the blade tips split apart and the blades were later shortened to give the turbine a 45-meter diameter.

Other Turbines from Stötten-Schnittlingen Test Field

Jaeger notes that there were a number of other turbines tested at Schnittlingen during the 1980s.[2]

  • Aerodynamik Consult FLAIR 8kW
  • Dornier 30kW
  • MAN Aeroman 12/20
  • Uni Karlsruhe Windftower 5,5kW
  • Uni Stuttgart OPTIWAlUNIWEX 45kW
  • Voith DEBRA-25
  • Voith WEC 520
  • WKZ ElektrOmat 20kW

The Flair turbine would be an extremely valuable addition to the museum’s collection if Jaeger can find an example. Hütter taught for many years at the University of Stuttgart’s Institute of Aircraft Design, alongside Professor Franz Wortman, himself well known for airfoil sections at the Institute of Aerodynamics. Wortman and his students pursued Hütter’s minimalist design philosophy to its logical conclusion: the one-blade FLAIR or Flexible Autonomous 1-Bladed Rotor.

Originally developed for the German washing machine company Böwe, FLAIR was subsequently sold to MBB. From it, MBB developed the Monopteros series of one-bladed wind turbines of the 1980s.[3]

The Dornier turbine was a 5.3-meter diameter, three-bladed Darrieus turbine installed in 1978 and would be another rare find.[4]

The Aeroman, ElektrOmat, and Debra 25 were all commercialized in the early days of the German wind industry. There may be examples of these turbines extant as well because several were used at the Kaiser-Wilhelm-Koog test site in northern Germany.

Among the turbines installed at Kaiser-Wilhelm-Koog in the late 1980s was the 25 meter diameter, 165 kW Adler 25. The three-blade, downwind turbine was developed from the work of Jens-Peter Molly on the DEBRA-25 (Deutsche Versuchsanstalt für Luft und Raumfart, DFVLR) research turbine. The Adler 25 was built by Köster Maschinenfabrik in Heide and named after a famous German engineer and wind turbine designer of the 1920s.

Jaeger and the Deutsches Windkraftmuseum would have quite a collection if it can get more examples of these early wind turbines of the modern era.

[1] Handschuh, Karl. Windkraft gestern und heute: Geschichte der Windenergienutzung in Baden-Württemberg. Staufen bei Freiburg: Ökobuch Verlag, 1991. pp. 74-75.

[2] Jaeger, Arne. “Rotorblatt Voith WEC 520: Grossexponat aus deutscher Forschung übernommen.” Windkraft Journal, 2022.

[3] Gipe, Paul. Wind Energy for the Rest of Us: A Comprehensive Guide to Wind Power and How to Use It., 2016. p. 96.

[4] Handschuh, Karl. p. 77.

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  • Who Was Dimitri Stein and was He the First with Wind in Post War Germany?
  • Operation of Ulrich Hütter’s StGW-34 at a test site in the Schwabian Alps
  • Photos of Kaiser-Wilhelm-Koog by Paul Gipe