Motorenfabrik Oberursel
Encyclopedia
Motorenfabrik Oberursel A.G. was a German manufacturer of automobile, locomotive
and aircraft engines situated in Oberursel (Taunus), near Frankfurt (Main), Germany. During World War I it supplied a major 100 hp-class rotary engine
that was used in a number of early-war fighter aircraft
designs. In 1921 the company merged with Deutz AG
, and then again in 1930 with Humboldt-Deutz Motoren, and finally in 1938 with Klöcknerwerke AG. From this point on they were known as the Klöckner-Humboldt-Deutz Oberursel factory, known primarily for their locomotive engines. Today they are part of Rolls-Royce plc
, and produce one family of their jet engine
s.
The factory in Oberursel is claimed to be the oldest surviving aircraft engine factory in the world.
system and produced a small one-cylinder stationary engine of about 4 hp, which he called the Gnom.
The following year he founded Willy Seck & Co. to sell the design, which became famous around the world. The engine was improved to achieve more power, but in 1897 the shareholders refused to allow Seck to develop a Gnom-powered car and he left the company. The company was reorganized as Motorenfabrik Oberursel the next year, and by 1900 had built 2,000 engines.
The same year the company granted a license to the Seguin brothers in Lyon to produce the Gnom in France. Sold under the French name Gnome
, the engine became so successful that they renamed their company to the same name. In 1908 they developed a rotary version of the basic Gnome system as the Gnome Omega
aircraft engine, and from there a series of larger versions of the same basic design. The new Gnome engines were wildly successful, powering many of the early record breaking aircraft.
In 1913 Motorenfabrik Oberursel took out a license on the French Gnome engine design and the similar Le Rhône 9C
. They produced both, the Gnomes as the U-series, and the Le Rhônes as the UR-series.
The Gnome Lambda
seven-cylinder 80 hp rotary engine was also produced by the Oberursel firm as the Oberursel U.0 Umlaufmotor (the generic German term for a rotary engine) as their first-ever powerplant for German military aircraft, and was used on the initial versions of the famous Fokker Eindecker
fighter, the Fokker E.I
.
of 100 hp, a clone of the Gnome Monosoupape
100 hp rotary, had the best power-to-weight ratio
of any German engine. It went on to power most of the early German fighters, such as the Fokker and Pfalz E-series monoplanes.
Oberursel also built a copy of Gnome's 14-cylinder Double Lambda
two-row rotary. This 160 hp (120 kW) engine, designated U.III in Germany, was difficult to build and quickly wore out in service. It was used on the Fokker E.IV and D.III designs.
The 110 hp Oberursel UR.II, the clone of the Le Rhône 9J
of the same power output, was the next major success. Fokker
bought the company in 1916 in order to guarantee supplies of the UR.II. This acquisition proved advantageous because Fokker was partial to rotary powered designs, and because supplies of the Mercedes D.III
engine were limited. The UR.II was used in the Fokker Dr.I
and Fokker D.VI
.
By 1917, the UR.II had been rendered obsolete by its relatively low power and poor performance at altitude. An 11-cylinder development, the UR.III, was not used operationally. Indeed, by 1918, rotary engines had largely fallen from favor with the Idflieg
and with pilots. The lack of castor oil
and the poor quality of the mineral oil substitute "Voltol" severely reduced engine life and reliability. Nevertheless, in the summer of 1918, the UR.II was intalled in the Fokker D.VIII
. The light weight and aerodynamic cleanliness of the D.VIII allowed it to achieve excellent performance even with the outdated UR.II.
After the war the company was purchased in 1921 by Gasmotorenfabrik Deutz, another gasoline engine manufacturer, who moved their two-stroke diesel
manufacturing to the Oberursel factories. In 1930 they merged with Humboldt-Deutz, but with only one product line. The factory was eventually closed in 1932 during the Great Depression
, reopening in 1934 for small-scale production.
, the DZ 710
16-cylinder boxer engine, and the DZ 720 32-cylinder H-block
made from twinned 710's. None of these designs reached operational use by the end of the war, when the factory was occupied by US troops.
In 1956 the factories were returned to Klöckner-Humboldt-Deutz, and from then on have been used primarily for gas turbine
development and production. For the next twenty years they produced a variety of designs, typically under license from other companies. In 1980 they were renamed KHD Luftfahrttechnik GmbH.
In 1990 the company was sold to what was then BMW Rolls-Royce. The new owners decided to use the Oberursel plants to produce an entirely modern engine for the "small end" of the aviation market, and started development of the Rolls-Royce BR700
family in 1991. The engines have since gone on to power a number of aircraft including Bombardier
, Gulfstream V
and the Boeing 717
.
Oberursel U.I
Oberursel U.II
Oberursel U.III
Oberursel Ur.II
Oberursel Ur.III
Locomotive
A locomotive is a railway vehicle that provides the motive power for a train. The word originates from the Latin loco – "from a place", ablative of locus, "place" + Medieval Latin motivus, "causing motion", and is a shortened form of the term locomotive engine, first used in the early 19th...
and aircraft engines situated in Oberursel (Taunus), near Frankfurt (Main), Germany. During World War I it supplied a major 100 hp-class rotary engine
Rotary engine
The rotary engine was an early type of internal-combustion engine, usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary and the entire cylinder block rotated around it...
that was used in a number of early-war fighter aircraft
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
designs. In 1921 the company merged with Deutz AG
Deutz AG
Deutz AG is an engine manufacturer, based in Cologne, Germany.-History:The company was founded by Nikolaus Otto, inventor of the four-stroke internal combustion engine, in 1864 as N. A...
, and then again in 1930 with Humboldt-Deutz Motoren, and finally in 1938 with Klöcknerwerke AG. From this point on they were known as the Klöckner-Humboldt-Deutz Oberursel factory, known primarily for their locomotive engines. Today they are part of Rolls-Royce plc
Rolls-Royce plc
Rolls-Royce Group plc is a global power systems company headquartered in the City of Westminster, London, United Kingdom. It is the world’s second-largest maker of aircraft engines , and also has major businesses in the marine propulsion and energy sectors. Through its defence-related activities...
, and produce one family of their jet engine
Jet engine
A jet engine is a reaction engine that discharges a fast moving jet to generate thrust by jet propulsion and in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets...
s.
The factory in Oberursel is claimed to be the oldest surviving aircraft engine factory in the world.
Early years
The company had its origins in 1891, when Willy Seck invented a new gasoline fuel injectionFuel injection
Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....
system and produced a small one-cylinder stationary engine of about 4 hp, which he called the Gnom.
The following year he founded Willy Seck & Co. to sell the design, which became famous around the world. The engine was improved to achieve more power, but in 1897 the shareholders refused to allow Seck to develop a Gnom-powered car and he left the company. The company was reorganized as Motorenfabrik Oberursel the next year, and by 1900 had built 2,000 engines.
The same year the company granted a license to the Seguin brothers in Lyon to produce the Gnom in France. Sold under the French name Gnome
Gnome et Rhône
Gnome et Rhône was a major French aircraft engine manufacturer. Between 1914 and 1918 they produced 25,000 of their 9-cylinder Delta and Le Rhône 110 hp rotary designs, while another 75,000 were produced by various licensees, powering the majority of aircraft in the first half of the war on...
, the engine became so successful that they renamed their company to the same name. In 1908 they developed a rotary version of the basic Gnome system as the Gnome Omega
Gnome Omega
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6....
aircraft engine, and from there a series of larger versions of the same basic design. The new Gnome engines were wildly successful, powering many of the early record breaking aircraft.
In 1913 Motorenfabrik Oberursel took out a license on the French Gnome engine design and the similar Le Rhône 9C
Le Rhône 9C
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6....
. They produced both, the Gnomes as the U-series, and the Le Rhônes as the UR-series.
The Gnome Lambda
Gnome Lambda
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6....
seven-cylinder 80 hp rotary engine was also produced by the Oberursel firm as the Oberursel U.0 Umlaufmotor (the generic German term for a rotary engine) as their first-ever powerplant for German military aircraft, and was used on the initial versions of the famous Fokker Eindecker
Fokker Eindecker
The Fokker Eindecker was a German World War I monoplane single-seat fighter aircraft designed by Dutch engineer Anthony Fokker. Developed in April 1915, the Eindecker was the first purpose-built German fighter aircraft and the first aircraft to be fitted with synchronizer gear, enabling the pilot...
fighter, the Fokker E.I
Fokker E.I
|-See also:-References:NotesBibliography* Boyne, Walter J. The Smithsonian Book of Flight for Young People. Washington, DC: Smithsonian Institution, 1988. ISBN 0-689-31422-1....
.
World War I
When World War I started the following year the Oberursel U.IOberursel U.I
The Oberursel U.I was an early German aircraft engine that powered many German fighter aircraft in the first part of World War I. It was a 9-cylinder air-cooled rotary engine, a licence-built copy of the Gnome Monosoupape that Oberursel was producing under licence before the war...
of 100 hp, a clone of the Gnome Monosoupape
Gnome Monosoupape
The Monosoupape , was a rotary engine design first introduced in 1913 by Gnome Engine Company...
100 hp rotary, had the best power-to-weight ratio
Power-to-weight ratio
Power-to-weight ratio is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power sources...
of any German engine. It went on to power most of the early German fighters, such as the Fokker and Pfalz E-series monoplanes.
Oberursel also built a copy of Gnome's 14-cylinder Double Lambda
Gnome Lambda
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6....
two-row rotary. This 160 hp (120 kW) engine, designated U.III in Germany, was difficult to build and quickly wore out in service. It was used on the Fokker E.IV and D.III designs.
The 110 hp Oberursel UR.II, the clone of the Le Rhône 9J
Le Rhône 9J
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6....
of the same power output, was the next major success. Fokker
Fokker
Fokker was a Dutch aircraft manufacturer named after its founder, Anthony Fokker. The company operated under several different names, starting out in 1912 in Schwerin, Germany, moving to the Netherlands in 1919....
bought the company in 1916 in order to guarantee supplies of the UR.II. This acquisition proved advantageous because Fokker was partial to rotary powered designs, and because supplies of the Mercedes D.III
Mercedes D.III
The Mercedes D.III, or F1466 as it was known internally, was a six-cylinder, liquid cooled inline aircraft engine built by Daimler and used on a wide variety of German aircraft during World War I. The initial versions were introduced in 1914 at 160 hp, but a series of changes improved this to...
engine were limited. The UR.II was used in the Fokker Dr.I
Fokker Dr.I
The Fokker Dr.I Dreidecker was a World War I fighter aircraft built by Fokker-Flugzeugwerke. The Dr.I saw widespread service in the spring of 1918...
and Fokker D.VI
Fokker D.VI
-Bibliography:* Gray, Peter and Owen Thetford. German Aircraft of the First World War. London: Putnam, 1962. ISBN 0-93385-271-1* Taylor, Michael J. H. Jane's Encyclopedia of Aviation. London: Crescent Books, 1993. ISBN 0-51710-316-8....
.
By 1917, the UR.II had been rendered obsolete by its relatively low power and poor performance at altitude. An 11-cylinder development, the UR.III, was not used operationally. Indeed, by 1918, rotary engines had largely fallen from favor with the Idflieg
Idflieg
The Idflieg was the bureau of the German War Office that oversaw German military aviation prior to and during World War I....
and with pilots. The lack of castor oil
Castor oil
Castor oil is a vegetable oil obtained from the castor bean . Castor oil is a colorless to very pale yellow liquid with mild or no odor or taste. Its boiling point is and its density is 961 kg/m3...
and the poor quality of the mineral oil substitute "Voltol" severely reduced engine life and reliability. Nevertheless, in the summer of 1918, the UR.II was intalled in the Fokker D.VIII
Fokker D.VIII
-See also:-References:* Weyl, A.R. Fokker: The Creative Years. 1988. ISBN 0-851778-17-8....
. The light weight and aerodynamic cleanliness of the D.VIII allowed it to achieve excellent performance even with the outdated UR.II.
After the war the company was purchased in 1921 by Gasmotorenfabrik Deutz, another gasoline engine manufacturer, who moved their two-stroke diesel
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
manufacturing to the Oberursel factories. In 1930 they merged with Humboldt-Deutz, but with only one product line. The factory was eventually closed in 1932 during the Great Depression
Great Depression
The Great Depression was a severe worldwide economic depression in the decade preceding World War II. The timing of the Great Depression varied across nations, but in most countries it started in about 1929 and lasted until the late 1930s or early 1940s...
, reopening in 1934 for small-scale production.
World War II
In 1940 during World War II all diesel research was relocated to Oberursel, where Dr. Ing. Adolf Schnürle led the development of much larger and more advanced engines for aircraft use. This led to the Klöckner-Humboldt-Deutz DZ 700 8-cylinder radial engineRadial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders point outward from a central crankshaft like the spokes on a wheel...
, the DZ 710
Klöckner-Humboldt-Deutz DZ 710
The Klöckner-Humboldt-Deutz DZ 710 was a German aircraft engine manufactured by Motorenfabrik Oberursel A.G. in the early 1940s. It was a 16-cylinder horizontally-opposed, two cycle diesel engine...
16-cylinder boxer engine, and the DZ 720 32-cylinder H-block
H engine
An H engine is an engine configuration in which the cylinders are aligned so that if viewed from the front, they appear to be in a vertical or horizontal letter H....
made from twinned 710's. None of these designs reached operational use by the end of the war, when the factory was occupied by US troops.
Post-World War II
For a short period in 1946 the factories were used as a tank repair depot.In 1956 the factories were returned to Klöckner-Humboldt-Deutz, and from then on have been used primarily for gas turbine
Gas turbine
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between....
development and production. For the next twenty years they produced a variety of designs, typically under license from other companies. In 1980 they were renamed KHD Luftfahrttechnik GmbH.
In 1990 the company was sold to what was then BMW Rolls-Royce. The new owners decided to use the Oberursel plants to produce an entirely modern engine for the "small end" of the aviation market, and started development of the Rolls-Royce BR700
Rolls-Royce BR700
-External links:* * *...
family in 1991. The engines have since gone on to power a number of aircraft including Bombardier
Bombardier Aerospace
Bombardier Aerospace is a division of Bombardier Inc. and is the third-largest airplane manufacturer in the world. It is headquartered in Dorval, Quebec, Canada.- History :...
, Gulfstream V
Gulfstream V
The Gulfstream V is a business jet aircraft produced by Gulfstream Aerospace. It is also used by the US military under the designation C-37A. The G500 and G550 are improved versions which are currently in production...
and the Boeing 717
Boeing 717
The Boeing 717 is a twin-engine, single-aisle jet airliner, developed for the 100-seat market. The airliner was designed and marketed by McDonnell Douglas as the MD-95, a third-generation derivative of the DC-9. Capable of seating of up to 117 passengers, the 717 has maximum range of...
.
Engines
Oberursel U.0Oberursel U.I
Oberursel U.II
Oberursel U.III
Oberursel Ur.II
Oberursel Ur.III