GM 1
GM 1 was a system for injecting nitrous-oxide into aircraft engines that was used by the Luftwaffe in World War II to boost the high-altitude performance of their aircraft. Without this system the Germans were severely disadvantaged above about 8 km (24,000 ft), because their lower-octane gasolines would not allow them to apply as much supercharger boost as their Allied counterparts. During 1943 and 1944 the Germans were countering USAAF air raids by the B-17 which generally flew at about 25,000 ft. Although the resonably good supercharger in the Daimler-Benz DB 601 allowed the Messerschmitt Me 109 operate with some effectiveness, this design from the early 1930s was no longer competitive. The Focke-Wulf FW 190 was considerably more capable, notably in warload, but it's BMW 801's single-stage supercharger left it robbed of power above 19,000 ft. When fighter met fighter, the German designs were always at a disadvantage. The "obvious" solution would to the improve the supercharger on the BMW 801, and several attemps along these lines were being made. However the Luftwaffe already had thousands of FW 190's in service, most of which were equipped with a system originally intended for low-altitude boost, MW 50. Adapting the existing plumbing with a new set of tanks containing nitrous-oxide resulted in the GM 1, also known under the code name "ha-ha" for laughing gas. On the 801D GM 1 resulted in an improvement of about 300 hp over 8 km. In alternate terms it boosted the altitude performance of the aircraft by about 2 km; whereas the engine would normally generate 1,000 hp at 9.8 km, with GM 1 turned on this power point was raised to 12 km. This allowed the aircraft to maintain some semblance of control at bomber altitudes, although the overall effect was minimal when the P-51 Mustang appeared. GM 1 was also fitted to a number of other engines which had also been originally fitted for MW 50, including the Junkers Jumo 213.
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