{{unreferenced, date=September 2008
GM-1 (''Göring Mischung'' 1) was a system for injecting
nitrous oxide
Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...
(laughing gas) into aircraft engines that was used by the ''
Luftwaffe
The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabtei ...
'' in
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
. This increased the amount of
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
in the fuel mixture, and thereby improved high-altitude performance. GM-1 was used on a number of modifications of existing fighter designs in order to counter the increasing performance of Allied fighters at higher altitudes.
A different system for low-altitude boost known as
MW 50
MW 50 (Methanol-''Wasser'' 50) was a 50-50 mixture of methanol and water (German: ''Wasser'') that was often sprayed into the supercharger of World War II aircraft engines primarily for its anti-detonation effect, allowing the use of increased bo ...
was also used, although GM-1 and MW 50 were rarely used on the same engine. MW-50 was a '' methanol''-''
water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
'' injection system, which injected a mixture of methanol and water into the cylinders to cool the mix. Cooling causes the air to become denser, therefore allowing more air into each cylinder for a given volume. This is the same principle that intercoolers use.
GM-1 was developed in 1940 by Otto Lutz to improve high-altitude performance. It could be used by fighters, destroyers, bombers and reconnaissance aircraft, though its first use was in the Bf 109E/Z fighter. Originally, it was liquified under high pressure and stored in several high-pressure vessels until it was found that low-temperature liquefied nitrous oxide gave better performance due to improved charge cooling. It could also be stored and handled more conveniently and was less vulnerable to enemy fire.
GM-1 was typically sprayed in liquid form directly into the supercharger intake from two jets of different bore while at the same time, the fuel flow was increased to take advantage of the additional oxygen from the nitrous oxide. The jets could be operated individually or in combination, yielding three steps of power increase, for example 120/240/360 HP at different GM-1 flow rates (60, 100 and 150 grams/sec). The development of a continuously variable injection system was considered, but apparently it never saw operational use.
Initially intended as standard equipment for the ''Luftwaffe'', in operational service it was found that GM-1 had some drawbacks. The additional weight of the equipment reduced performance on all missions, while the system was only used in the cases where the aircraft went to very high altitudes. GM-1 also became less attractive than originally imagined when in 1943, the previous trend towards ever increasing combat altitudes ended.
While GM-1 saw little use in the second half of the war, the Focke-Wulf Ta 152H, which had been developed as a dedicated high-altitude interceptor, also received a GM-1 system to provide it with superior performance at high altitude. The Ta 152H was one of the few designs to support both GM-1 and MW 50.
Similar systems have been used in racing cars and hot rods.