The Jumo 210 was Junkers Motoren's first production inverted V12 gasoline aircraft engine, first produced in the early 1930s. Depending on the version it produced between 610 and 730 PS and can be considered a counterpart of the

Rolls-Royce Kestrel The Kestrel or type F is a 21 litre (1,300 in³) 700 horsepower (520 kW) class V-12 aircraft engine from Rolls-Royce, their first cast-block engine and the pattern for most of their future piston-engine designs. Used during the interwar ...

in many ways. Although originally intended to be used in almost all pre-war designs, rapid progress in aircraft design quickly relegated it to the small end of the power scale by the late 1930s. Almost all aircraft designs switched to the much larger Daimler-Benz DB 600, so the 210 was produced only for a short time before Junkers responded with a larger engine of their own, the

Junkers Jumo 211 The Jumo 211 was a German inverted V-12 aircraft engine, Junkers Motoren's primary aircraft engine of World War II. It was the direct competitor to the Daimler-Benz DB 601 and closely paralleled its development. While the Daimler-Benz en ...

Design and development

The first gasoline-burning aviation power plants that the Junkers Motorenwerke ever built were the L1 and L2 single overhead camshaft (SOHC) liquid-cooled

inline-six The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine bala ...

aviation engines of the early and mid-1920s. Development of this line led up through the L8. All of these were developments of the

BMW IIIa BMW IIIa was an inline six-cylinder SOHC valvetrain, water-cooled aircraft engine, the first-ever engine produced by Bayerische Flugzeugwerke AG, who, at the time, were exclusively an aircraft engine manufacturer. Its success laid the foundatio ...

inline-six SOHC German World War I aviation engine, which BMW allowed as they were no longer interested in development of their WWI designs. The Junkers L55 engine, however, was the very first V12 layout aviation powerplant of any type created by the Junkers firm, using a pair of the earlier straight-six L5 engines as a basis for an "upright" liquid-cooled V12 aviation engine, as the contemporary

BMW VI The BMW VI was a water-cooled V-12 aircraft engine built in Germany in the 1920s. It was one of the most important German aero engines in the years leading up to World War II, with thousands built. It was further developed as the BMW VII and ...

engine already was. Development of the Jumo 210 itself started in 1931 under the designation L10. The L10 was Germany's first truly modern engine design, featuring three valves per cylinder, an inverted-V layout, a

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. The current categorisation is that a supercharger is a form of forced indu ...

as standard equipment, and a cast cylinder block. The 210 was odd in that the cylinders were machined into a block along with one side of the crankcase, two such parts being bolted together side-by-side to form the engine. Normal construction techniques used three parts, two cylinder blocks and a separate crankcase. The L10 was first ran in static tests on October 22, 1932. With the official formation of the RLM in 1933, numerical engine designations by manufacturer was rationalized with Junkers receiving the "200 block", the L10 becoming the 210. Type approval was achieved in March 1934, and it first flew on July 5, 1934 installed in a Junkers W33. The design had initially aimed for 700 PS, but the prototypes delivered only about 600 PS, so there was some disappointment in the industry. Nevertheless, almost all German aircraft designs of the era were based on the 210, which is why they were so small compared to other countries' efforts. Initial production of the 610 PS (602 hp, 449 kW) Jumo 210A started in late 1934. Further development led in 1935 to the 640 PS (631 hp, 471 kW) 210B and 210C. Both added a new

for improved performance, along with a dump valve to avoid overboost. The B model had its propeller geared at 1:1.55 (prop:engine rpm) for high-speed use, while the C model was geared at 1:1.63 for slower flying speeds. In 1936 the new 670 PS (661 hp, 493 kW) 210D and 210E were introduced, which had the same gearing as the B and C but used a new two-speed supercharger to increase takeoff power and altitude performance. The Jumo 210G had a direct injection system developed by August Lichte. The Jumo system used a small pump piston positioned beside each of the main cylinders, driven off the crank shaft. The injector used a simple check valve to prevent internal pressure from blowing back into the fuel line, and the pump was timed to inject at the proper point in the intake cycle. Inclusion of the injection system increased takeoff performance by about 20 PS without increasing boost rates and it also reduced fuel consumption. For those reasons most newer German engine types were set up with fuel injection systems. The Jumo 210G was rated at 730 PS (720 hp, 534 kW) and was only available for fast aircraft like the

Bf 109 The Messerschmitt Bf 109 is a German World War II fighter aircraft that was, along with the Focke-Wulf Fw 190, the backbone of the Luftwaffe's fighter force. The Bf 109 first saw operational service in 1937 during the Spanish Civil War an ...

and Bf 110 but not for slow aircraft like the

Ju 87 The Junkers Ju 87 or Stuka (from ''Sturzkampfflugzeug'', "dive bomber") was a German dive bomber and ground-attack aircraft. Designed by Hermann Pohlmann, it first flew in 1935. The Ju 87 made its combat debut in 1937 with the Luftwaffe's Con ...

. Further developments were planned as Jumo 210F and 210H, but never built. In 1935 the Jumo 210H, with twin exhaust valves for each cylinder, was used for development of the Jumo 211. The Jumo 210-S was a special development by the DVL with rotary disc valves, as used in KM-8 torpedo engine. Production of the Jumo 210 came to an end in about 1938.

Applications

* Arado Ar 68 - only in Ar 98E *

Focke-Wulf Fw 159 The Focke-Wulf Fw 159 was an experimental German fighter of the 1930s, designed by Kurt Tank which never reached production, as it was considered inferior to the He 112 and Bf 109. It was a heavier variant of the Focke-Wulf Fw 56, with several ...

* Focke-Wulf Fw 187 * Heinkel He 112 * Junkers Ju 87 - only in Ju 87A * Messerschmitt Bf 109 - only in Bf 109 A-D * Messerschmitt Bf 110 - only in Bf 110 A/B *

Messerschmitt Me 262 The Messerschmitt Me 262, nicknamed ''Schwalbe'' (German: " Swallow") in fighter versions, or ''Sturmvogel'' (German: " Storm Bird") in fighter-bomber versions, is a fighter aircraft and fighter-bomber that was designed and produced by the Ge ...

V1 - only in first test flight, prototype's BMW 003 axial-flow jet engines failed shortly after takeoff, aircraft brought around and back on the nose-mounted Jumo 210's power alone.

Specifications (Jumo 210)

References

Bibliography

* * * * *''A History of Aircraft Piston Engines'', Herschel Smith
The Hugo Junkers Homepage-engines section on L-series engines

External links