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. Nitrous oxide, also known as dinitrogen oxide or dinitrogen monoxide, is a chemical compound with chemical formula N2O. Under room conditions it is a colourless non-flammable gas, with a pleasant slightly sweet odor. ... The term aircraft engine, for the purposes of this article, refers to aircraft reciprocating, or rotary, internal combustion engines as opposed to jet engines or turboprops. ... The Luftwaffe (literally, air weapon, pronounced looft-vaaf-feh) is the air force of Germany. ... Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km into the air. ...

GM-1 was developed in 1940 in order 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 liquified nitrous oxide gave better performance due to improved charge cooling and also could be stored and handled more conveniently. (Bf 109 was the official Reichsluftfahrtministerium designation, though some late_war aircraft actually carried the Me 109 designation stamped onto their aircraft type plates. ...

Initially intended as standard equipment for the Luftwaffe, it was soon found that in operational service, GM-1 had some drawbacks, such as the additional weight of the equipment and the requirement to keep it at a low temperature once the aircraft had been filled up, and it was only used for certain mission types where its advantages outweighed its disadvantages. GM-1 also was became less attractive than originally imagined when in 1943, the previous trend towards ever increasing combat altitudes ended.

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. The development of a continously variable injection system was considered, but apparently it never saw operational use.

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 late in the war, also received a GM-1 system to provide it with superior performance at high altitude. The Focke-Wulf Ta 152 was a WW2 Luftwaffe fighter aircraft. ...