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{{Short description|Early German axial turbojet engine}}
{{More citations needed|date=September 2011}}
{{infobox aero engine
| name = BMW 003
| image = File:BMW 003 jet engine.JPG
| caption = BMW 003 engine at the [[Luftwaffenmuseum der Bundeswehr]]. Airflow from L to R.
 |engine_type= [[Turbojet]]
 |manufacturer= [[BMW]]
 |national_origin= Germany
 |first_run=August 1940
 |major_applications= [[Heinkel He 162]]
 |number_built = 3,500
 |developed_from =
 |developed_into = {{ubl | [[BMW 018]] | [[BMW GT 101]] | [[SNECMA Atar]] }}
 |variants_with_their_own_articles =
}}

The '''BMW 003''' (full RLM designation '''109-003''') is an early [[Axial engine|axial]] [[turbojet]] engine produced by [[BMW|BMW AG]] in Germany during [[World War II]]. The 003 and the [[Junkers Jumo 004]] were the only German turbojet engines to reach production during World War II.

Work had begun on the design of the BMW 003 before its contemporary, the Jumo 004, but prolonged developmental problems meant that the BMW 003 entered production much later, and the aircraft projects that had been designed with it in mind were re-engined with the Jumo powerplant instead. The most famous case of this was the [[Messerschmitt Me 262]], which used the 003 in two of the V-series prototypes and in the two experimental A-1b aircraft. The only production aircraft to use the BMW 003 were the [[Heinkel He 162]] and the later C-series, four-engined versions of the [[Arado Ar 234]].

About 3,500 BMW 003 engines were built in Germany, but very few were ever installed in aircraft.<ref>{{cite web |title=BMW 003 Turbojet Engine |url=https://airandspace.si.edu/collection-objects/bmw-003-turbojet-engine/nasm_A19670125000 |website=airandspace.si.edu |access-date=10 November 2021}}</ref> The engine also formed the basis for turbojet development in [[Japan]] during the war, and in the [[Soviet Union]] following the war. A larger derivative was the [[BMW 018]], but only three prototypes had been built by the end of the war.

==Design and development==
The practicality of jet propulsion had been demonstrated in Germany in early 1937 by [[Hans von Ohain]] working with the [[Heinkel]] company. Recognising the potential of the invention, the [[Ministry of Aviation (Nazi Germany)|Reich Air Ministry]] ({{langx|de|Reichsluftfahrtministerium}}, abbreviated RLM) encouraged Germany's aero engine manufacturers to begin their own programmes of jet engine development, offering contracts to both Junkers and BMW for an engine capable of {{convert|690|kg|lb|abbr=on|order=flip}} [[thrust|static thrust]].<ref>Christopher, John.  ''The Race for Hitler's X-Planes'' (The Mill, Gloucestershire: History Press, 2013), p.60.</ref>

The BMW 003 began development as a project of the [[Brandenburgische Motorenwerke]] ([[Brandenburg]] Motor Works, known as "''Bramo''"), under the direction of [[Hermann Östrich]] and assigned the RLM designation '''109-003''' (using the RLM's "109-" prefix, common to all jet and rocket engine projects). Bramo was also developing another turbojet, the 109–002. In 1939, BMW bought out Bramo, and in the acquisition, obtained both engine projects. The 109-002 had a very sophisticated [[contra-rotation|contra-rotating]] [[Gas compressor|compressor]] design intended to eliminate [[torque]], but was abandoned in favour of the simpler engine, which in the end proved to have enough development problems of its own.

Construction began late in the same year and the engine ran for the first time in August 1940,<ref>Gunston 1989, p.27.</ref> but produced only {{convert|150|kg|lb|abbr=on|order=flip}} thrust, just half what was desired.<ref>Christopher, p.60.</ref> The first flight test took place in mid-1941, mounted underneath a [[Messerschmitt Bf 110]] testbed airframe. Problems continued, however, so delaying the program that while the Me 262 V1 prototype airframe (the first aircraft intended to use the engine) was ready for flight-testing, there were no power plants available for it and it actually began flight tests with a supplementary, conventional [[Junkers Jumo 210]] piston engine in the nose. It was not until November 1941 that the Me 262 V1 was flown with BMW engines, which both failed during the test.<ref>Christopher, p.61.</ref> The prototype aircraft had to return to the airfield on the power of the piston engine, which was still fitted.<ref>{{Cite book |url=https://books.google.com/books?id=dSLBdP22fq0C&pg=PA31 |title=The Jet Race and the Second World War |first=Sterling Michael |last=Pavelec |publisher=Greenwood Publishing Group |year= 2007 |isbn=978-0-275-99355-9}}</ref><ref>{{Cite book |last1=Radinger |first1=Will |first2= Walter |last2=Schick |title=Me262 (in German) |location=Berlin |publisher=Avantic Verlag GmbH |year=1996 |isbn=978-3-925505-21-8 |page=23 }}</ref>

The general usage of the BMW powerplant was abandoned for the Me 262, except for two experimental examples of the plane known as the Me 262 A-1b. The few ''Messerschmitt Me 262 A-1b'' test examples built used the more developed version of the 003 jet, recording an official top speed of {{convert|800|km/h|mph|abbr=on|order=flip}}. The Me 262A-1a production version used the competing Jumo 004, whose heavier weight required the wings to be swept back in order to move the [[center of gravity]] into the correct position. Work on the 003 continued anyway, and by late 1942 it had been made far more powerful and reliable. The improved engine was flight tested under a [[Junkers Ju 88]] in October 1943 and was finally ready for mass production in August 1944. Completed engines earned a reputation for unreliability; the time between major overhauls (not technically a [[Time between overhaul|TBO]]) was about 50 hours.<ref name="Christopher, p.76">Christopher, p.76.</ref> (The competing Jumo 004's was between thirty and fifty, and may have been as low as ten.)<ref name="Christopher, p.76"/> Through 1944 the 003's reliability improved, making it a suitable power plant for air frame designs competing for the [[Emergency Fighter Program|''Jägernotprogramm'']]’s [[light fighter]] production contract. which was won by the Heinkel He 162 ''Spatz'' design.

Developments of the engine included the 003C, which raised thrust to {{convert|900|kg|lb|abbr=on}} — in the same thrust class as the competing Jumo 004B, but some {{convert|136|kg|lb|abbr=on}} lighter in weight; and the 003D, which raised it to nearly {{convert|1100|kg|lb|abbr=on}},<ref>{{cite web |url=http://legendsintheirowntime.com/LiTOT/Content/1946/Av_4603_DA_BMW003.html |title=Design Analysis of BMW 003 Turbojet - "Gas Turbine Units Developed by BMW - Model Designation: BMW 003D" |last1=Schulte |first1=Rudolph C. |date=1946 |website=legendsintheirowntime.com |publisher=United States Army Air Force - Turbojet and Gus Turbine Developments, HQ, AAF |access-date=September 3, 2016 |quote=Static SL thrust 2,420 lb @ 10,000 rpm |archive-date=September 29, 2018 |archive-url=https://web.archive.org/web/20180929074301/http://legendsintheirowntime.com/LiTOT/Content/1946/Av_4603_DA_BMW003.html |url-status=dead }}</ref> which added one extra compressor stage beyond the seven of the earlier designs, and an extra turbine stage,<ref>Christopher, p.73.</ref> with the thrust-weight ratio of 16.58 N/kg for the 003D at only {{convert|649|kg||abbr=on|order=flip}} in weight, being some 30% greater than the {{convert|12.63|N/kg||abbr=on|order=flip}} figure for the {{convert|950|kg|adj=on}} [[Heinkel HeS 011]]A.

Only two German production aircraft used the 003. The first was the [[Heinkel He 162]]A ''Spatz'' (since the ''Volksjäger'' light fighter design competition mandated its use),<ref>Christopher, John.  ''The Race for Hitler's X-Planes'' (The Mill, Gloucestershire: History Press, 2013), p.145.</ref> with the ''Spatz'' utilizing an 003E version, designed to possess ventral mounting points to allow it to be mounted atop the fuselage of an aircraft. The other was the four-engined [[Arado Ar 234]]C reconnaissance-bomber variants, which were designed to use what was supposed to be the "more available" engine,<ref>Christopher, pp.73–74.</ref> despite its primary allocation for the He 162A.

The BMW 003 proved cheaper in materials than the company's own [[BMW 801|801]] [[radial engine|radial]], {{Reichsmark|12,000|link=yes}} to {{Reichsmark|40,000}}, and cheaper than the [[Junkers Jumo 213]] inverted V12 piston engine at {{Reichsmark|35,000}}, but slightly more costly than the competing Junkers Jumo 004's {{Reichsmark|10,000}}.<ref name="Christopher, p.74">Christopher, p.74.</ref> Moreover, the 004 needed only 375 hours to complete (including manufacture, assembly, and shipping), compared to 1,400 for the 801.<ref>Christopher, p.75.</ref> At Kolbermoor, location of the [[Heinkel]]-[[Hirth]] engine works, the [[Fedden Mission]], led by Sir [[Roy Fedden]], found jet-engine manufacturing was simpler and required lower-skill labor and less sophisticated tooling than piston engine production; in fact, most of making of hollow turbine blades and [[sheet metal]] work on jets could be done by tooling used in making automobile [[Quarter panel|body panel]]s.<ref>Christopher, pp.74–75.</ref> The lifetime of the combustion chambers was estimated at 200 hours.<ref name="Christopher, p.76"/>

[[File:BMW 003 Riedelanlasser.jpg|thumb|right|Preserved BMW 003 with Riedel flat-twin mechanical APU fitted]]

The BMW 003 utilized nearly the same starting method as its slightly more powerful Jumo 004 competitor: one of [[Norbert Riedel]]'s 10 PS flat-twin two-stroke engines, installed within the engine's intake diverter as a mechanical [[auxiliary power unit|APU]], to get the 003's central shaft rotating for operation. An American military-authored post-war review of the BMW 003 stated that an electric starter of some sort was used to "turn over" the Riedel APU, with no existing photos of either wartime or restored BMW 003s showing the "D-shape" pull handle so prominent on the noses of many museum-preserved Jumo 004's intake diverters.<ref>{{cite web |url=http://legendsintheirowntime.com/LiTOT/Content/1946/Av_4603_DA_BMW003.html |title=Design Analysis of BMW 003 Turbojet - "Starting the Engine" |last1=Schulte |first1=Rudolph C. |date=1946 |website=legendsintheirowntime.com |publisher=United States Army Air Force - Turbojet and Gus Turbine Developments, HQ, AAF |access-date=September 3, 2016 |quote=Starting procedure is as follows: Starting engine is primed by closing electric primer switch, then ignition of turbojet and ignition '''and electric starting motor''' of [[Norbert Riedel|Riedel engine]] are turned on (this engine can also be started manually by pulling a cable). After the Riedel unit has reached a speed of about 300 rpm, it automatically engages the compressor shaft of the turbojet. At about 800 rpm of the starting engine, starting fuel pump is turned on, and at 1,200 rpm the main (J-2) fuel is turned on. The starter engine is kept engaged until the turbojet attains 2,000 rpm, at which the starter engine and starting fuel are turned off, the turbojet rapidly accelerating to rated speed of 9,500 rpm on the J-2 fuel |archive-date=September 29, 2018 |archive-url=https://web.archive.org/web/20180929074301/http://legendsintheirowntime.com/LiTOT/Content/1946/Av_4603_DA_BMW003.html |url-status=dead }}</ref>

==="Mixed-power" upgrade===

One late version of the engine added a small [[rocket]] motor (the [[BMW 109-718]]) at the rear and usually just above the exhaust of the engine, which added some {{convert|1250|kg|lb|abbr=on}} thrust each for three to five minutes, for take off and short dashes.<ref>Christopher, p.124.</ref> In this configuration, it was known as the BMW 003R and was tested, albeit with some serious reliability problems, on single prototypes for advanced models of the Me 262 (the Me 262C-2b ''Heimatschützer II'' [Home Defender II]),<ref name="Christopher, p.125">Christopher, p.125.</ref> and He 162 (He 162E). Both prototypes flew under hybrid jet/rocket power during March 1945,<ref name="Christopher, p.125"/> though records do not indicate the results of testing with the 162E.

Only about 500 examples of the BMW 003 were built,<ref name="Christopher, p.74"/>{{Verify source|date=November 2021|reason=Smithsonian link says 3500}} but the Fedden Mission postwar estimated total German jet engine production by mid-1946 could have reached 100,000 units a year, or more.<ref name="Christopher, p.76"/>

The 003 was intended for export to Japan, but working examples of the engine were never supplied. Instead, Japanese engineers used cross-section drawings to design an indigenous turbojet, the [[Ishikawajima Ne-20]].<ref name="Edwin1 (2009)">Edwin 2009, p. 312-314.</ref>

===Turboshaft development===

The 003 was selected as the basis for a [[gas turbine]] development project for the German military's anticipated need for what is today called a [[turboshaft]] powerplant for multiple needs — this project was called the [[GT 101]], using the 003 axial-flow turbojet as the starting point in mid-November 1944. Its original purpose would have been to re-engine the [[Panther tank]] with a turboshaft-based power system capable of up to a 1,150 PS usable shaft horsepower rating into an [[Armored fighting vehicle|AFV]]'s drivetrain, from an engine weight of only {{convert|450|kg|lb|abbr=on|order=flip}}, giving it a 27&nbsp;hp/ton [[power-to-weight ratio]] — just over twice the factor that the Panther's original gasoline-fueled [[Maybach HL230|Maybach V12 piston engine]] provided.<ref>{{cite book |last=Kay |first=Antony |date=2002 |title=German Jet Engine and Gas Turbine Development 1930-1945 |location=Shrewsbury, UK  |publisher=Airlife Publishing |isbn=9781840372946 }}</ref>

===Post-war use===
Following the war, two captured 003s powered the prototype of the first [[Soviet Union|Soviet]] jet, the [[Mikoyan-Gurevich MiG-9]]. Blueprints for BMW engines had been seized by Soviet forces from both the Basdorf-Zühlsdorf plant near Berlin and the notorious [[Mittelwerk]] slave labor facility near [[Nordhausen, Thuringia|Nordhausen]]. Production of the 003 was set up at the "Red October" GAZ 466 (''Gorkovsky Avtomobilny Zavod'', or Gorky Automobile Plant) in [[Leningrad]] and in Kuznetsov along KMPO, where the engine was mass-produced from 1947 under the designation RD-20 (''reactivnyi dvigatel'', or "jet drive").<ref>{{cite book | last = Albrecht | first = Ulrich | title = The Soviet Armaments Industry | publisher = Routledge | date = 1994 |isbn = 978-3-7186-5313-3}}</ref>

After the Allied occupation of Germany, [[Marcel Dassault]] assisted Hermann Östrich in moving from the [[Allied Occupation Zones in Germany#American Zone of Occupation|American Zone]] of occupied Germany into the [[Allied Occupation Zones in Germany#French Zone of Occupation|French Zone]]. Within a couple of years, he was working for [[Voisin (aircraft)|Voisin]], a division of [[SNECMA]], France's state-owned aircraft engine company. Using the basic design of the 003, he produced the larger [[SNECMA Atar|Atar]] jet engine that powered Dassault's [[Dassault Ouragan|Ouragan]], [[Dassault Mirage III]] and [[Dassault Mystère|Mystère]] fighters.<ref>{{cite book | last = von Wogau | first = Karl | title = The Path to European Defence | publisher = Maklu | date = 2004 |isbn = 978-90-6215-923-9}}</ref>

==Variants==
''Data from:''Aircraft Engines of the world 1946<ref name=Wilkinson>{{cite book|last=Wilkinson|first=Paul H.|title=Aircraft Engines of the world 1946|year=1946|publisher=Sir Isaac Pitman & Sons|location=London|pages=300–301}}</ref> and ''Design Analysis of BMW 003 Turbojet'' by Maj Rudolph C Schulte, Project Officer, Turbojet and Gas Turbine Developments, HQ, [[USAAF]]<ref>{{cite web |url=http://legendsintheirowntime.com/LiTOT/Content/1946/Av_4603_DA_BMW003.html |title=Design Analysis of BMW 003 Turbojet |last1=Schulte |first1=Rudolph C. |date=1946 |website=legendsintheirowntime.com |publisher=United States Army Air Force - Turbojet and Gus Turbine Developments, HQ, AAF |access-date=September 3, 2016 |archive-date=September 29, 2018 |archive-url=https://web.archive.org/web/20180929074301/http://legendsintheirowntime.com/LiTOT/Content/1946/Av_4603_DA_BMW003.html |url-status=dead }}</ref>
;BMW 003A-1 (TL 109–003):Prototype, {{convert|1,320|lbf|kN|abbr=on|2|order=flip}} / 8,000 rpm / sea level, weight of {{convert|609|kg|lb|abbr=on}}.
;BMW 003A-2 (TL 109–003):Initial production variant, {{convert|1,760|lbf|kN|abbr=on|2|order=flip}} / 9,500 rpm / sea level.
;BMW 003C (TL 109–003):Improved design, reduced weight A-2, {{convert|1,980|lbf|kN|abbr=on|2|order=flip}}, equal to Jumo 004B) / 9,500 rpm / sea level
;BMW 003D (TL 109–003):Improved design 003C, {{convert|2,420|lbf|kN|abbr=on|2|order=flip}} / 10,000 rpm / sea level, weight of {{convert|649|kg|lb|abbr=on}} [{{convert|301|kg|lb|abbr=on}} lighter than the HeS 011], one extra compressor and turbine stage added for higher thrust, only lengthening the engine by {{convert|11+15/16|in|abbr=on|order=flip}} overall compared to the A-2.
;BMW 003E :With ventral mounting points for use atop the fuselage, on the [[Heinkel He 162]] and [[Henschel Hs 132]].
;BMW 003R (TLR 109–003):An 003A-2 subtype turbojet with a [[BMW 109-718]] (RLM powerplant number 109-718) liquid-fuel rocket fixed permanently above the jet exhaust nozzle, running on a hypergolic combination of [[R-stoff]] (a.k.a. Tonka or TONKA-250, 50% [[triethylamine]] and 50% [[xylidine]]) for fuel and [[SV-Stoff]] (aka [[Red fuming nitric acid|RFNA]] propellants: 94% [[Nitric acid|HNO<sub>3</sub>]], 6% [[Dinitrogen tetroxide|N<sub>2</sub>O<sub>4</sub>]]) oxidizer, code-named ''Salbei'' (sage). The 003R delivered a combined thrust of {{convert|4,510|lbf|kN|abbr=on|2|order=flip}} for 3 minutes.

==Applications==
*[[Arado Ar 234]]V6, V8 prototypes and Ar 234C (four engines used)
*[[Heinkel He 162]] (single jet engine)
*[[Junkers Ju 287]] (two engines used for Ju 287 V2, six engines used for V3 and Ju 287A-1)
*[[Messerschmitt Me 262]] (A-1b test version, and ''Heimatschützer II'' experimental twin-BMW 003R powered interceptor only - all twin-engined)

==Specifications (BMW 003A-2)==
{{jetspecs
<!-- If you do not understand how to use this template, please ask at [[Wikipedia talk:WikiProject Aircraft]] -->
<!-- Please include units where appropriate (main comes first, alt in parentheses). If data are missing, leave the parameter blank (do not delete it). For additional lines, end your alt units with )</li> and start a new, fully-formatted line with <li> -->
|ref=Aircraft Engines of the world 1946<ref name=Wilkinson/>
|type=[[axial flow]] [[turbojet]]
|length={{convert|143|in|cm|abbr=on|order=flip}}
|diameter={{convert|27.2|in|cm|abbr=on|order=flip}}
|weight={{convert|1,375|lb|kg|abbr=on|1|order=flip}}
|compressor=7-stage axial
|combustion=1 [[annular combustor|annular]]
|turbine=single-stage axial
|fueltype=J-2 [[diesel fuel]] or [[gasoline]]
|oilsystem=Pressure feed at {{convert|85|psi|kPa|abbr=on|0|order=flip}}, dry sump with 4 [[scavenge pump]]s with [[annular tank]] and cooler, using oil grade 163 [[S.U. secs]] (35 [[Viscosity#Stokes .28unit.29|cSt]]) ([[D.T.D 44D]]) at {{convert|38|°C|°F}}
|power=
|thrust= {{convert|1,760|lbf|kN|abbr=on|order=flip}} at 9,500 rpm at sea level for [[takeoff]]
|compression=3.1:1
|bypass=
|aircon={{convert|42.5|lb/s|kg/s|abbr=on|order=flip}} at 9,500 [[rpm]]
|turbinetemp={{convert|1,418|°F|°C|order=flip}}
|fuelcon=
|specfuelcon={{convert|1.4|tsfc|si tsfc|order=flip}}
|power/weight=
|thrust/weight=1.13
*'''Normal, static:'''  {{convert|1,550|lbf|kN|abbr=on|2|order=flip}} / 9,000 rpm / sea level
*'''Military flight:''' {{convert|1,400|lbf|kN|abbr=on|2|order=flip}} / 9,500 rpm / {{convert|2,500|m|ft|abbr=on|0}} / {{convert|900|km/h|mph kn|abbr=on|0}}
*'''Normal, flight:''' {{convert|640|lbf|kN|abbr=on|2|order=flip}} / 11,500 rpm / {{convert|11,000|m|ft|abbr=on|0}} / {{convert|900|km/h|mph kn|abbr=on|0}}
}}

==See also==
{{aircontent
<!-- other related articles that have not already linked: -->
|see also=
<!-- designs which were developed into or from this aircraft: -->
|related=
* [[BMW 018]]
* [[BMW GT 101]]
* [[Snecma Atar]]
<!-- For aircraft engine articles. Engines that are of similar to this design: -->
|similar engines=
* [[Junkers Jumo 004]]
* [[Ishikawajima Ne-20]]
* [[Heinkel HeS 30]]
* [[Metropolitan-Vickers F.2|Metrovick F.2]]
* [[Westinghouse J30]]
<!-- relevant lists that this aircraft appears in: -->
|lists=
*[[List of aircraft engines]]
<!-- See [[WP:Air/PC]] for more explanation of these fields. -->
}}

==Notes==
{{Reflist}}

==Bibliography==
*{{cite book|last=Wilkinson|first=Paul H.|title=Aircraft Engines of the world 1946|year=1946|publisher=Sir Isaac Pitman & Sons|location=London|pages=300–301}}
* Dyer, Edwin M (2009). ''Japanese Secret Projects, Experimental Aircraft of the IJA and IJN 1939-1945''. Midland Publishing, 2009, {{ISBN|9781857803174}}
* Gunston, Bill. ''World Encyclopedia of Aero Engines''. Cambridge, England. Patrick Stephens Limited, 1989. {{ISBN|1-85260-163-9}}
* ''Jane's Fighting Aircraft of World War II''. London. Studio Editions Ltd, 1989. {{ISBN|0-517-67964-7}}
* Kay, Antony, ''German Jet Engine and Gas Turbine Development 1930–1945'', Airlife Publishing, 2002, {{ISBN|9781840372946}}

==External links==
{{Commons category|BMW 003}}

*[http://legendsintheirowntime.com/LiTOT/Content/1946/Av_4603_DA_BMW003.html USAAF Maj. Rudolph Schulte's ''Design Analysis of BMW 003 Turbojet''] {{Webarchive|url=https://web.archive.org/web/20180929074301/http://legendsintheirowntime.com/LiTOT/Content/1946/Av_4603_DA_BMW003.html |date=2018-09-29 }}

{{BMW aeroengines}}
{{RLM jet/rocket designations}}

[[Category:BMW aircraft engines]]
[[Category:1940s turbojet engines]]