Hot steam balloon

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A hot steam balloon is a balloon that uses hot steam from water as a lifting gas . Due to its lower molecular weight of 18 at atmospheric pressure, water vapor with a temperature well above 100 ° C has only about half the density of typical ambient air . According to Archimedes' principle, this difference in density leads to static buoyancy, as in gas or hot air balloons . The first test model of a hot steam balloon rose in Germany in 2006.

functionality

Aerostats experience a buoyancy because their lifting gas has a lower density than the surrounding air. For a load capacity of 1000 kg you need 877 m³ hydrogen , 947 m³ helium , 3633 m³ hot air at 100 ° C or 1567 m³ hot steam at 100 ° C. The latter has a load capacity that is more than twice as high as hot air and is a cost-effective alternative to helium. As a non-flammable gas, it is safer than hydrogen.

Technically, hot steam balloons are more demanding than conventional gas or hot air balloons. Heating is required for longer ascents, as the condensation of water vapor as a result of cooling must be prevented. Special requirements are also placed on the balloon envelope. It not only has to be tight, but also heat-resistant and offer strong thermal insulation . In addition, superheated steam is a reactive , corrosive gas that the balloon material has to withstand.

history

The idea of using water vapor as a lifting gas for balloons and airships was first formulated in 1818 by Sir George Cayley , an English engineer who had already studied flight in the first half of the 19th century. In 1908, the German chemist Hugo Erdmann protected the idea of ​​using superheated steam or a mixture of this and other gases as a lifting gas for aircraft . Erdmann wanted to use eiderdown for thermal insulation . He couldn't get beyond the first experiments.

The first free-flying steam balloon in the world was developed between 2003 and 2006 by Alexander Bormann and Stefan Skutnik at the Institute of Aerospace at the Technical University of Berlin under the name "HeiDAS UH", where HeiDAS stands for hot steam aerostat, UH for ultra hot. A prototype first rose in the laboratory on May 7, 2003. By 2006 an unmanned balloon with a diameter of 2.35 m and a capacity of 7 cubic meters of steam was built. The superheated steam reached a temperature of 150 ° C, which required a particularly temperature- resistant and solid cover material ( polyimide film reinforced with aramid filament yarn ). "HeiDAS UH" is based on the Rozière principle . The foil gas container is thermally insulated and a heat exchanger reduces the flow of heat. Like a hot air balloon or a Rozière, the “HeiDAS UH” has a burner that is used to control rising and falling, so that no extra ballast is required.

literature

Web links

Individual evidence

  1. ↑ a b Alexander Bormann, Jan Philipp Herrmann, Skutnik Stefan: Alternative Buoyancy Concepts: First Numerical and Experimental Results from a Hot Steam Balloon (HeiDAS) . AIAA's 3rd Annual Aviation Technology, Integration, and Operations (ATIO) Forum, Denver, Colorado, November 17, 2003. doi : 10.2514 / 6.2003-6840 .
  2. ↑ George Cayley: Aërial Navigation . In: The Philosophical Magazine and Journal . tape 47 , 1816, p. 81–86 ( limited preview in Google Book Search).
  3. ↑ Patent DE214019 : filling gas for aircraft. Registered on August 14, 1908 , published October 2, 1909 , inventor: Hugo Erdmann. ‌