Junkers Jumo 210
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The Jumo 210 was Junkers Motoren's first production gasoline aircraft engine, produced just before the start of World War II. It produced about 650hp in common versions, and can be considered a counterpart of the Rolls-Royce Kestrel 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.
Development of the Jumo 210 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 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, 22nd 1932. With the official formation of the RLM in 1933, engine naming 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 5th 1934 on a Junkers W33. The design had initially aimed for 700hp, but the prototypes delivered only about 600 hp, 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 country's efforts.
Initial production of the 610hp Jumo 210A started in 1934. This model was quickly replaced by the 635hp 210B and 210C, differing only in the propeller gearing. Both added a new supercharger for improved performance, along with a waste gate to avoid overboost. The B model was geared at 0.57 for high-speed use, while the C model was geared at 0.62 for slower flying speeds. These models were in turn replaced by the 640hp 210 D and 210E, which had the same gearing as the B/C. A new two-speed supercharger resulted in the Jumo 210Da/Ea which had higher takeoff power.
The Jumo 210G was the world's first engine with direct fuel injection, developed by Dr. 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 is said to have increased takeoff performance by about 50hp, which is why it quickly became a feature of almost all German engines. Jumo 210Ga had a different supercharger gear ratio. The airscrew drive was 0.57. The G model became the most built subtype of the Jumo 210 and was used on the Bf 109, He 112, Me 110, and Junkers Ju 87.
Further developments were planned as Jumo 210F and 210H, but never built. In 1935 the Jumo 210H was used for development of the Jumo 211. A Jumo 210S was a special development of the DVL with special regulation mechanisms. Production of the Jumo 210 came to an end in about 1938.
[edit] References
- A History of Aircraft Piston Engines, Herschel Smith
- - this source claims the 210 remained in production until 1942
