Junkers Jumo 004
Encyclopedia
The Jumo 004 was the world's first turbojet engine in production and operational use, and the first successful axial compressor
jet engine ever built. Some 8,000 units were manufactured by Junkers in Germany
during late World War II
and powered the operational Messerschmitt Me 262
jet fighter, Arado Ar 234
jet reconnaissance / bomber, and prototypes of the Horten Ho 229
aircraft. Variants of the engine were produced in Eastern Europe in the years following the war.
working with the Heinkel
company. Most of the RLM
remained uninterested, but Helmut Schelp and Hans Mauch saw the potential of the concept and encouraged Germany's aero engine manufacturers to begin their own programmes of jet engine development. The companies remained skeptical and little new development was carried out. Eventually in 1939 Otto Mader, head of Junkers Motoren (Jumo), stated that even if the concept was useful, he had no one to work on it. Schelp responded by stating that Dr Anselm Franz
, then in charge of Junkers' turbo-
and supercharger
development, would be perfect for the job. Franz started his development team later that year, and the project was given the RLM designation 109-004 (the 109- prefix was common to all jet projects).
Franz opted for a design that was at once conservative and revolutionary. His design differed from von Ohain's in that he utilised a new type of compressor
which allowed a continuous, straight flow of air through the engine (an axial compressor
), recently developed by the Aerodynamische Versuchsanstalt (AVA - Aerodynamic Research Institute) at Göttingen
. The axial-flow compressor not only had excellent performance, about 78% efficient in "real world" conditions, but it also had a smaller cross-section, important for a high-speed aircraft design.
On the other hand, he aimed to produce an engine that was far below its theoretical potential, in the interests of expediting development and simplifying production. One major decision was to opt for a simple combustion area using six "flame cans", instead of the more efficient single annular can. For the same reasons, he collaborated heavily on the development of the engine's turbine
with Allgemeine Elektrizitäts-Gesellschaft
(AEG - General Electric Company) in Berlin
, and instead of building development engines, opted to begin work immediately on the prototype of an engine that could be put straight into production. Franz's conservative approach came under question from the RLM, but was vindicated when even given the developmental problems that it was to face, the 004 entered production and service well ahead of its more technologically advanced competitor, the BMW 003.
The first prototype 004A, which was constructed to run on Diesel fuel, was first tested in October 1940, though without an exhaust nozzle. It was benchtested at the end of January 1941 to a top thrust of 430 kgf (4,216.9 N), and work continued to increase the output, the RLM contract having set a minimum of 600 kgf (5,884 N) thrust.
Vibration problems with the compressor blades delayed the program at this point, until a new stator design by Max Bentele
solved the problem. The original alloy compressor blades were replaced with steel ones and with the new stators in place the engine developed 5.9 kN (5,900 N) in August, and passed a 10-hour endurance run at 9.8 kN (9,800 N) in December. The first flight test took place on March 15 1942, when a 004A was carried aloft by a Messerschmitt Bf 110
to run up the engine in flight.
On July 18, one of the prototype Messerschmitt Me 262
s flew for the first time under jet power from its 004 engines, and the 004 was ordered into production by the RLM to the extent of 80 engines.
The initial 004A engines built to power the Me 262 prototypes had been built without restrictions on materials, and they used scarce raw materials such as nickel
, cobalt
, and molybdenum
in quantities which were unacceptable in production. Franz realized that the Jumo 004 would have to be redesigned to incorporate a minimum of these strategic materials, and this was accomplished. All the hot metal parts, including the combustion chamber, were changed to mild steel protected by an aluminum coating, and the hollow turbine blades were produced from folded and welded Cromadur alloy (12% chromium, 18% manganese, and 70% iron) developed by Krupp
, and cooled by compressed air "bled" from the compressor. The engine's operational lifespan was shortened, but on the plus side it became easier to construct.
The first production model of the 004B weighed 220 lb (99.8 kg) less than the 004A, and in 1943 had passed several 100 hour tests, with a time between overhauls of 50 hours being achieved.
Later in 1943 a series of engines suffered vibration problems which dragged on. Eventually, in December, blade-vibration specialist Max Bentele
was once again brought in during a meeting at the RLM headquarters, and the problem was solved by raising the blades' natural frequency by increasing their taper, shortening them by 1 millimeter, and reducing the operating speed of the engine from 9,000 to 8,700 rpm.
It was not until early 1944 that full production could finally begin. These setbacks were the principal factor delaying the Luftwaffe's introduction of the Me 262 into squadron service.
Given the lower-quality steels used in the 004B, these engines typically only had a service life of some 10-25 hours, perhaps twice this in the hands of a skilled pilot. Another shortcoming of the engine, common to all early turbojets, was its sluggish throttle response. Worse, it was fairly easy to inject too much fuel into the engine by throttling up too quickly, allowing heat to build up before the cooling air could remove it. This led to softening of the turbine blades, and was a major cause for engine failures. Nevertheless, it made jet power for combat aircraft a reality for the first time.
The exhaust area of the 004 featured a variable geometry nozzle, which had a special restrictive body nicknamed the Zwiebel (German for onion, due to its shape when seen from the side) which had roughly 40 cm (16 inch) fore-and-aft travel to vary the jet exhaust's cross-sectional area for thrust control, as the active part of a pioneering "divergent-convergent" nozzle format.
One interesting feature of the 004 was the starter system, which consisted of a Riedel 10 hp (7 kW) 2-stroke motorcycle
engine hidden in the intake. A hole in the extreme nose of the centrebody contained a pull-handle which started the piston engine, which in turn spun up the turbine. Two small gasoline tanks were fitted in the annular intake.
The Jumo 004 could run on three types of fuel:
, designated M-04, to power the Avia S-92 which was itself a copy of the Me 262. Jumo 004 copies were also built in the Soviet Union
as the RD-10 engine, where they powered the Yakovlev Yak-15
as well as many prototype jet fighters.
In France
, captured 004s powered the Sud-Ouest SO 6000 Triton and the Arsenal VG-70.
for increased thrust, but was not built. The 004D improved fuel efficiency with a two-stage fuel injector, and introduced a new throttle control that avoided dumping too much fuel into the engine during throttle-ups. The 004D had passed testing and was ready to enter production in place of the 004B, when the war ended. The 004E was a 004D model with an improved exhaust area for better altitude performance.
A much more advanced model based on the same basic systems was also under development as the Jumo 012. The 012 was based on a "two-spool" system, in which two turbines, spinning at different speeds, drove two separate sections of the compressor for more efficiency. In a jet engine the compressor typically uses up about 60% of all the power generated, so any improvements can have a dramatic effect on fuel use. Plans were also underway to use the 012's basic concept in an engine outwardly identical to the 004, known as the 004H, which improved specific fuel consumption from the 004B's 1.39 kg/(daN*h) to a respectable 1.20 kg/(daN*h), a decrease of about 15%.
Layout: ax=axial flow compressor stages, in=individual combustion chambers, tu=turbine stages.
, the engine was used to power the experimental Junkers Ju 287
, and prototypes of the Horten Ho 229
and Heinkel He 280
. There were plans to install it in the Heinkel He 162
as well as the Focke-Wulf Ta 183
and Henschel Hs 132
then under development.
Axial compressor
Axial compressors are rotating, airfoil-based compressors in which the working fluid principally flows parallel to the axis of rotation. This is in contrast with other rotating compressors such as centrifugal, axi-centrifugal and mixed-flow compressors where the air may enter axially but will have...
jet engine ever built. Some 8,000 units were manufactured by Junkers in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
during late 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...
and powered the operational Messerschmitt Me 262
Messerschmitt Me 262
The Messerschmitt Me 262 Schwalbe was the world's first operational jet-powered fighter aircraft. Design work started before World War II began, but engine problems prevented the aircraft from attaining operational status with the Luftwaffe until mid-1944...
jet fighter, Arado Ar 234
Arado Ar 234
The Arado Ar 234 was the world's first operational jet-powered bomber, built by the German Arado company in the closing stages of World War II. Produced in very limited numbers, it was used almost entirely in the reconnaissance role, but in its few uses as a bomber it proved to be nearly impossible...
jet reconnaissance / bomber, and prototypes of the Horten Ho 229
Horten Ho 229
The Horten H.IX, RLM designation Ho 229 was a late–World War II prototype fighter/bomber designed by Reimar and Walter Horten and built by Gothaer Waggonfabrik...
aircraft. Variants of the engine were produced in Eastern Europe in the years following the war.
Design and development
The feasibility of jet propulsion had been demonstrated in Germany in early 1937 by Hans von OhainHans von Ohain
Hans Joachim Pabst von Ohain was a German engineer, one of the inventors of jet propulsion.Frank Whittle, who patented in 1930 in the United Kingdom, and Hans von Ohain, who patented in 1936 in Germany, developed the concept independently during the late 1930s...
working with the Heinkel
Heinkel
Heinkel Flugzeugwerke was a German aircraft manufacturing company founded by and named after Ernst Heinkel. It is noted for producing bomber aircraft for the Luftwaffe in World War II and for important contributions to high-speed flight.-History:...
company. Most of the RLM
Reich Air Ministry
thumb|300px|The Ministry of Aviation, December 1938The Ministry of Aviation was a government department during the period of Nazi Germany...
remained uninterested, but Helmut Schelp and Hans Mauch saw the potential of the concept and encouraged Germany's aero engine manufacturers to begin their own programmes of jet engine development. The companies remained skeptical and little new development was carried out. Eventually in 1939 Otto Mader, head of Junkers Motoren (Jumo), stated that even if the concept was useful, he had no one to work on it. Schelp responded by stating that Dr Anselm Franz
Anselm Franz
Dr. Anselm Franz was a pioneering Austrian jet engine engineer known for the development of the Jumo 004, the world's first mass-produced turbojet engine by Nazi Germany during World War II, and his work on turboshaft designs in the U.S...
, then in charge of Junkers' turbo-
Turbocharger
A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...
and 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,...
development, would be perfect for the job. Franz started his development team later that year, and the project was given the RLM designation 109-004 (the 109- prefix was common to all jet projects).
Franz opted for a design that was at once conservative and revolutionary. His design differed from von Ohain's in that he utilised a new type of compressor
Gas compressor
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...
which allowed a continuous, straight flow of air through the engine (an axial compressor
Axial compressor
Axial compressors are rotating, airfoil-based compressors in which the working fluid principally flows parallel to the axis of rotation. This is in contrast with other rotating compressors such as centrifugal, axi-centrifugal and mixed-flow compressors where the air may enter axially but will have...
), recently developed by the Aerodynamische Versuchsanstalt (AVA - Aerodynamic Research Institute) at Göttingen
Göttingen
Göttingen is a university town in Lower Saxony, Germany. It is the capital of the district of Göttingen. The Leine river runs through the town. In 2006 the population was 129,686.-General information:...
. The axial-flow compressor not only had excellent performance, about 78% efficient in "real world" conditions, but it also had a smaller cross-section, important for a high-speed aircraft design.
On the other hand, he aimed to produce an engine that was far below its theoretical potential, in the interests of expediting development and simplifying production. One major decision was to opt for a simple combustion area using six "flame cans", instead of the more efficient single annular can. For the same reasons, he collaborated heavily on the development of the engine's turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
with Allgemeine Elektrizitäts-Gesellschaft
AEG
Allgemeine Elektricitäts-Gesellschaft was a German producer of electrical equipment founded in 1883 by Emil Rathenau....
(AEG - General Electric Company) in Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
, and instead of building development engines, opted to begin work immediately on the prototype of an engine that could be put straight into production. Franz's conservative approach came under question from the RLM, but was vindicated when even given the developmental problems that it was to face, the 004 entered production and service well ahead of its more technologically advanced competitor, the BMW 003.
Technical description and testing
Vibration problems with the compressor blades delayed the program at this point, until a new stator design by Max Bentele
Max Bentele
Max Bentele was a pioneer in the field of jet aircraft turbines and mechanical engineering...
solved the problem. The original alloy compressor blades were replaced with steel ones and with the new stators in place the engine developed 5.9 kN (5,900 N) in August, and passed a 10-hour endurance run at 9.8 kN (9,800 N) in December. The first flight test took place on March 15 1942, when a 004A was carried aloft by a Messerschmitt Bf 110
Messerschmitt Bf 110
The Messerschmitt Bf 110, often called Me 110, was a twin-engine heavy fighter in the service of the Luftwaffe during World War II. Hermann Göring was a proponent of the Bf 110, and nicknamed it his Eisenseiten...
to run up the engine in flight.
On July 18, one of the prototype Messerschmitt Me 262
Messerschmitt Me 262
The Messerschmitt Me 262 Schwalbe was the world's first operational jet-powered fighter aircraft. Design work started before World War II began, but engine problems prevented the aircraft from attaining operational status with the Luftwaffe until mid-1944...
s flew for the first time under jet power from its 004 engines, and the 004 was ordered into production by the RLM to the extent of 80 engines.
The initial 004A engines built to power the Me 262 prototypes had been built without restrictions on materials, and they used scarce raw materials such as nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
, cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
, and molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...
in quantities which were unacceptable in production. Franz realized that the Jumo 004 would have to be redesigned to incorporate a minimum of these strategic materials, and this was accomplished. All the hot metal parts, including the combustion chamber, were changed to mild steel protected by an aluminum coating, and the hollow turbine blades were produced from folded and welded Cromadur alloy (12% chromium, 18% manganese, and 70% iron) developed by Krupp
Krupp
The Krupp family , a prominent 400-year-old German dynasty from Essen, have become famous for their steel production and for their manufacture of ammunition and armaments. The family business, known as Friedrich Krupp AG Hoesch-Krupp, was the largest company in Europe at the beginning of the 20th...
, and cooled by compressed air "bled" from the compressor. The engine's operational lifespan was shortened, but on the plus side it became easier to construct.
The first production model of the 004B weighed 220 lb (99.8 kg) less than the 004A, and in 1943 had passed several 100 hour tests, with a time between overhauls of 50 hours being achieved.
Later in 1943 a series of engines suffered vibration problems which dragged on. Eventually, in December, blade-vibration specialist Max Bentele
Max Bentele
Max Bentele was a pioneer in the field of jet aircraft turbines and mechanical engineering...
was once again brought in during a meeting at the RLM headquarters, and the problem was solved by raising the blades' natural frequency by increasing their taper, shortening them by 1 millimeter, and reducing the operating speed of the engine from 9,000 to 8,700 rpm.
It was not until early 1944 that full production could finally begin. These setbacks were the principal factor delaying the Luftwaffe's introduction of the Me 262 into squadron service.
Given the lower-quality steels used in the 004B, these engines typically only had a service life of some 10-25 hours, perhaps twice this in the hands of a skilled pilot. Another shortcoming of the engine, common to all early turbojets, was its sluggish throttle response. Worse, it was fairly easy to inject too much fuel into the engine by throttling up too quickly, allowing heat to build up before the cooling air could remove it. This led to softening of the turbine blades, and was a major cause for engine failures. Nevertheless, it made jet power for combat aircraft a reality for the first time.
The exhaust area of the 004 featured a variable geometry nozzle, which had a special restrictive body nicknamed the Zwiebel (German for onion, due to its shape when seen from the side) which had roughly 40 cm (16 inch) fore-and-aft travel to vary the jet exhaust's cross-sectional area for thrust control, as the active part of a pioneering "divergent-convergent" nozzle format.
One interesting feature of the 004 was the starter system, which consisted of a Riedel 10 hp (7 kW) 2-stroke motorcycle
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
engine hidden in the intake. A hole in the extreme nose of the centrebody contained a pull-handle which started the piston engine, which in turn spun up the turbine. Two small gasoline tanks were fitted in the annular intake.
The Jumo 004 could run on three types of fuel:
- J-2, its standard fuel, a synthetic fuelSynthetic fuelSynthetic fuel or synfuel is a liquid fuel obtained from coal, natural gas, oil shale, or biomass. It may also refer to fuels derived from other solids such as plastics or rubber waste. It may also refer to gaseous fuels produced in a similar way...
produced from coal. - Diesel oil.
- Aviation gasoline; not considered desirable due to its high rate of consumption.
Postwar production
Following World War II, Jumo 004s were built in small numbers by Malešice in CzechoslovakiaCzechoslovakia
Czechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992...
, designated M-04, to power the Avia S-92 which was itself a copy of the Me 262. Jumo 004 copies were also built in the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
as the RD-10 engine, where they powered the Yakovlev Yak-15
Yakovlev Yak-15
The Yakovlev Yak-15, NATO reporting name: Feather, USAF/DOD designation Type 2) was a first-generation Soviet turbojet fighter developed by the Yakovlev design bureau immediately after World War II. It used a reverse-engineered German Junkers Jumo 004 engine...
as well as many prototype jet fighters.
In France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, captured 004s powered the Sud-Ouest SO 6000 Triton and the Arsenal VG-70.
Variants
A number of more advanced versions were in development at the end of the war. The 004C included an afterburnerAfterburner (engine)
An afterburner is an additional component added to some jet engines, primarily those on military supersonic aircraft. Its purpose is to provide a temporary increase in thrust, both for supersonic flight and for takeoff...
for increased thrust, but was not built. The 004D improved fuel efficiency with a two-stage fuel injector, and introduced a new throttle control that avoided dumping too much fuel into the engine during throttle-ups. The 004D had passed testing and was ready to enter production in place of the 004B, when the war ended. The 004E was a 004D model with an improved exhaust area for better altitude performance.
A much more advanced model based on the same basic systems was also under development as the Jumo 012. The 012 was based on a "two-spool" system, in which two turbines, spinning at different speeds, drove two separate sections of the compressor for more efficiency. In a jet engine the compressor typically uses up about 60% of all the power generated, so any improvements can have a dramatic effect on fuel use. Plans were also underway to use the 012's basic concept in an engine outwardly identical to the 004, known as the 004H, which improved specific fuel consumption from the 004B's 1.39 kg/(daN*h) to a respectable 1.20 kg/(daN*h), a decrease of about 15%.
Variants table
| RLM Designation | Type | Layout | Thrust or power | Weight | Speed |
|---|---|---|---|---|---|
| 109-004B | Turbojet | 8ax 6in 1tu | 8.8 kN (1984 lbf) | 745 kg (1642 lb) | 8700 rpm |
| 109-004C | Turbojet | 8ax 6in 1tu | 10.0 kN (2238 lbf) | 720 kg (1588 lb) | 8700 rpm |
| 109-004D | Turbojet | 8ax 6in 1tu | 10.3 kN (2315 lbf) | 745 kg (1642 lb) | 10000 rpm |
| 109-004H | Turbojet | 11ax 8in 2tu | 17.7 kN (3970 lbf) | 1200 kg (2646 lb) | 6600 rpm |
| 109-012 | Turbojet | 11ax 6in 2tu | 27.3 kN (6130 lbf) | 2000 kg (4410 lb) | 5300 rpm |
| 109-022 | Turboprop | 11ax 8in 2tu | 4600 ehp (3.4 MW) | 2600 kg (5733 lb) | 5000 rpm |
Layout: ax=axial flow compressor stages, in=individual combustion chambers, tu=turbine stages.
Applications
Apart from the Me 262 and Arado Ar 234Arado Ar 234
The Arado Ar 234 was the world's first operational jet-powered bomber, built by the German Arado company in the closing stages of World War II. Produced in very limited numbers, it was used almost entirely in the reconnaissance role, but in its few uses as a bomber it proved to be nearly impossible...
, the engine was used to power the experimental Junkers Ju 287
Junkers Ju 287
-Bibliography:* Hitchcock, Thomas H. Junkers 287 . Acton, MA: Monogram Aviation Publications, 1974. ISBN 0-914144-01-4.-External links:*...
, and prototypes of the Horten Ho 229
Horten Ho 229
The Horten H.IX, RLM designation Ho 229 was a late–World War II prototype fighter/bomber designed by Reimar and Walter Horten and built by Gothaer Waggonfabrik...
and Heinkel He 280
Heinkel He 280
The Heinkel He 280 was the first turbojet-powered fighter aircraft in the world. It was inspired by Ernst Heinkel's emphasis on research into high-speed flight and built on the company's experience with the He 178 jet prototype. A combination of technical and political factors led to it being...
. There were plans to install it in the Heinkel He 162
Heinkel He 162
The Heinkel He 162 Volksjäger was a German single-engine, jet-powered fighter aircraft fielded by the Luftwaffe in World War II. Designed and built quickly, and made primarily of wood as metals were in very short supply and prioritised for other aircraft, the He 162 was nevertheless the fastest of...
as well as the Focke-Wulf Ta 183
Focke-Wulf Ta 183
The Focke-Wulf Ta 183 Huckebein was a design for a jet-powered fighter aircraft intended as the successor to the Messerschmitt Me 262 and other day fighters in Luftwaffe service during World War II. It was developed only to the extent of wind tunnel models when the war ended, but the basic design...
and Henschel Hs 132
Henschel Hs 132
-Note:There is a widely available image that purports to show the completed Hs 132V1 outside the Henschel plant. This is actually an artist's impression by Gert Heumann.-See also:-References:NotesBibliography...
then under development.