MW 50
Encyclopedia
MW 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-detonant
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.
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%. This increased the cooling performance but made it easier to freeze, the mixture intended to be used for lower-altitude missions. EW 30 and EW 50 mixtures also existed, which substituted methanol with ethanol
; in emergency, pure water could be used.
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 100 hp on the BMW 801
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 500 hp. At sea level
, this allowed the 1600 hp engine to run at over 2000 hp. MW 50 was fully effective up to about 6000 m (19,685 ft), above which it added only about 4% extra power, due largely to charge cooling.
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. 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
missions. 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
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 reduce non-boosted performance and tune the supercharger for higher altitudes.
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 (the Erhöhte Notleistung [Increased Emergency Performance] system), in place of the MW 50. While this was not as effective, it did increase boost without the complexity of the additional tanking and plumbing. Additionally, many of the late-war engines also included a system for high-altitude boost, GM-1
, which was intended to add oxygen to the fuel/air mix by injecting nitrous oxide
into the supercharger instead of employing higher boost levels.
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
and water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
(German: Wasser) that was often sprayed into the supercharger
Supercharger
A supercharger is an air compressor used for forced induction of an internal combustion engine.The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally aspirated engine, which allows more fuel to be burned and more work to be done per cycle,...
of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
aircraft engines primarily for its anti-detonant
Engine knocking
Knocking in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.The...
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.
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%. This increased the cooling performance but made it easier to freeze, the mixture intended to be used for lower-altitude missions. EW 30 and EW 50 mixtures also existed, which substituted methanol with ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
; in emergency, pure water could be used.
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 100 hp on the BMW 801
BMW 801
The BMW 801 was a powerful German air-cooled radial aircraft engine built by BMW and used in a number of German military aircraft of World War II. The engine's cylinders were in two rows of seven cylinders each, the bore and stroke were both 156 mm , giving a total capacity of 41.8 litres...
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 500 hp. At sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
, this allowed the 1600 hp engine to run at over 2000 hp. MW 50 was fully effective up to about 6000 m (19,685 ft), above which it added only about 4% extra power, due largely to charge cooling.
The increased power could be used for a maximum of 10 minutes at a time, much like the American war emergency power
War emergency power
War Emergency Power is an American term for the throttle setting on some World War II military aircraft engines. For use in emergency situations, it produced more than 100% of the engine's normal rated power for a limited amount of time, often about five minutes...
setting for their own aircraft, with at least five minutes between each application. 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
Interceptor aircraft
An interceptor aircraft is a type of fighter aircraft designed specifically to prevent missions of enemy aircraft, particularly bombers and reconnaissance aircraft. Interceptors generally rely on high speed and powerful armament in order to complete their mission as quickly as possible and set up...
missions. 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
Messerschmitt Bf 109
The Messerschmitt Bf 109, often called Me 109, was a German World War II fighter aircraft designed by Willy Messerschmitt and Robert Lusser during the early to mid 1930s...
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
Junkers Jumo 213
|-See also:-Bibliography:* Jane's Fighting Aircraft of World War II. London. Studio Editions Ltd, 1989. ISBN 0-517-67964-7-External links:*...
, which relied on it to reduce non-boosted performance and tune the supercharger for higher altitudes.
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 (the Erhöhte Notleistung [Increased Emergency Performance] system), in place of the MW 50. While this was not as effective, it did increase boost without the complexity of the additional tanking and plumbing. Additionally, many of the late-war engines also included a system for high-altitude boost, GM-1
GM-1
GM-1 , colloquially known as Haha-Gerät was a system for injecting nitrous oxide into aircraft engines that was used by the Luftwaffe in World War II. This increased the amount of oxygen in the fuel mixture, and thereby improve high-altitude performance...
, which was intended to add oxygen to the fuel/air mix by injecting nitrous oxide
Nitrous oxide
Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...
into the supercharger instead of employing higher boost levels.