MW50
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MW 50 (Methanol-''Wasser'' 50) was a 50-50 mixture of
methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often ab ...
and
water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
(German: ''Wasser'') that was often sprayed into the
supercharger In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement (engine), displacement. It is a form of forced induction that is mechanically ...
of
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
aircraft engines An aircraft engine, often referred to as an aero engine, is the power component of an aircraft Air propulsion, propulsion system. Aircraft using power components are referred to as powered flight. Most aircraft engines are either Reciprocating ...
primarily for its anti-detonation effect, allowing the use of increased boost pressures. Secondary effects were cooling of the engine and charge cooling. Higher boost was only effective at altitudes below the full-throttle height, where the supercharger could still provide additional boost pressure that was otherwise wasted, while the smaller secondary effects were useful even above that altitude.


Composition

MW 50 is something of a misnomer, as it is actually a mixture of three fluids: 50% methanol acting primarily to achieve optimum anti-detonant effect, secondarily as an anti-freeze; 49.5% water; and 0.5% ''Schutzöl'' 39, an oil-based anti-corrosion additive. The similar MW 30 increased the water to 69.5% and decreased methanol to 30%.Bridgeman 1989, p. 296. This increased the cooling performance but made it easier to freeze at -18 degrees C as opposed to -50 C for MW 50). As a result, this mixture was intended to be used for lower-altitude missions. EW 30 and EW 50 mixtures also existed, which substituted methanol with
ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...
; in emergency, pure water could be used.


Effect

The effect of MW 50 injection could be dramatic. Simply turning on the system allowed the engine to pull in more air due to the charge cooling effect, boosting performance by about on the
BMW 801 The BMW 801 was a powerful Nazi Germany, German Air-cooled engine, air-cooled 14-cylinder-radial engine, radial aircraft engine built by BMW and used in a number of German Luftwaffe aircraft of World War II. Production versions of the Radial e ...
and DB 605. However, the MW 50 also allowed the supercharger to be run at much higher boost levels as well, for a combined increase of . At
sea level Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...
, this allowed the engine to run at over . MW 50 was fully effective up to about , above which it added only about 4% extra power, due largely to charge cooling.


Time limits

The increased power could be used for a maximum of 10 minutes at a time, much like the American war emergency power setting for their own aircraft, with at least five minutes between each application.Bridgeman 1989, p. 297. Aircraft generally carried enough MW 50 for about two ten-minute periods of use, allowing them to increase their climb rate and level speed in combat for
interception In Ball game, ball-playing Competitive sport, competitive team sports, an interception or pick is a move by a player involving a pass of the ball—whether by foot or hand, depending on the rules of the sport—in which the ball is intended for ...
missions.


Applications

Fittings for MW 50 first appeared on the BMW 801D in 1942, but it never went into production for this engine because the cylinder heads developed micro-cracks when MW 50 was used. Instead, the DB 605-engined later versions of the
Messerschmitt Bf 109 The Messerschmitt Bf 109 is a monoplane fighter aircraft that was designed and initially produced by the Nazi Germany, German aircraft manufacturer Messerschmitt#History, Bayerische Flugzeugwerke (BFW). Together with the Focke-Wulf Fw 190, the ...
were fitted with an MW 50 injection system, beginning in early 1944. Later engine designs all included the fittings as well, notably the Junkers Jumo 213, which relied on it to increase non-boosted performance and tune the supercharger for higher altitudes.


Other systems

MW 50 was not the only charge cooling system to be used by the Germans. Some engines dedicated to high altitude included an intercooler instead, as they would be needing the cooling for longer periods of time. The 801D also included the ability to spray gasoline into the supercharger instead of MW 50. (The ''Erhöhte Notleistung'' ncreased Emergency Performancesystem.) While this was not as effective, it did increase boost without the complexity of the additional tanking and plumbing. Many of the late-war engines also included a system for high-altitude boost, GM-1, which added oxygen to the fuel/air mix by injecting
nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or factitious air, among others, is a chemical compound, an Nitrogen oxide, oxide of nitrogen with the Chemical formula, formula . At room te ...
into the supercharger instead of employing higher boost levels.


See also

*
Water injection (engines) In internal combustion engines, water injection, also known as anti-detonant injection (ADI), can spray water into the incoming air or fuel- air mixture, or directly into the combustion chamber to cool certain parts of the induction system where ...
* War emergency power


References


Notes


Bibliography

* Bridgman, L, (ed.) (1989) ''Jane's fighting aircraft of World War II.'' Crescent. {{refend Aircraft engines fr:Injection d'eau-méthanol