GM-1

from Wikipedia, the free encyclopedia

GM-1 was a process for increasing the performance of aircraft engines above full pressure altitude by injecting nitrous oxide (laughing gas), which was used by the German Air Force during the Second World War .

The injection of nitrous oxide as a means of increasing performance was based on a proposal submitted by Otto Lutz to the German Research Institute for Aviation in 1939 . The first development and testing took place at the Rechlin E3 test center in cooperation with the Lower Saxony device construction company . The first flight tests were carried out with a Bf 109 E with a DB 601 A engine. In the course of the tests, the good applicability and efficiency of the system proved.

The aim was to compensate for the lack of oxygen above full pressure by injecting oxygen or even to achieve an increase in performance above normal performance. The injection of pure oxygen was found to be damaging to the engine due to the strong tendency to knock during combustion and severe corrosion of the hot, metallic combustion chamber wall. The process using an oxygen carrier, which was developed in the German Reich and successfully used in several German aircraft, has proven itself excellently in the war effort. Nitrogen monoxide (chemical formula N 2 O, laughing gas) was used as the oxygen carrier, from which the mixture was initially listed under the code name “HA-HA”. It later became known as the so-called Göring Mixture GM 1 .

The gain in performance can be attributed to three engine-related improvements:

  1. The charging of the engine improves its volumetric efficiency .
  2. The cooling of the charge air by evaporating the liquid gas increases its thermodynamic efficiency .
  3. Replacing air with nitrous oxide increases the calorific value .

While pressure-liquefied N 2 O was initially used (necessary pressure for liquefaction 80 bar), from 1941/42, due to the bombardment sensitivity of the containers, cold liquefied laughing gas (boiling temperature −90 ° C) was used. For this purpose, heat-insulated containers had to be developed for use and transport.

The injection pressure was 4 bar. With some models like the Jumo 213E, the injection quantity could be regulated in three stages of 60, 100 and 150 g / s. With maximum injection, a performance gain of up to 400 HP could be achieved depending on the engine type at the operating altitude. With a Bf 109 G-1 / R2 with a GM-1 system, 100 km / h speed gains could be achieved at an altitude of 12,000 m and a peak height of 13,800 m. When used in high-altitude reconnaissance aircraft Ju 88 T with BMW-801 -G-2 engines, the performance, which in these machines dropped from 1730 to 880 hp at an altitude of 10,000 m, was increased to 1430 hp by the GM-1.

literature

  • Dietmar Hermann: With oxygen to better performance - doping for the engine . In: Flugzeug Classic, 6/2017, pp. 30–35.

Web links

Individual evidence

  1. ↑ a b c Kyrill Gersdorff, Kurt Grasmann, Helmut Schubert: Aircraft engines and jet engines. Development history of German aviation engines from the beginnings to the international joint developments. (German aviation; Vol. 2). 3rd edition. Bernard & Graefe Verlag, Bonn 1995, ISBN 3-7637-6107-1 , pp. 160-162.
  2. ^ Karl R. Pawlas: Increase in performance through additional injection. In: Ders .: Aviation Lexicon. Entry ID 8061-100-1.