Junkers Jumo 211

The Jumo 211 was an inverted V-12 aircraft engine, Junkers Motoren's primary aircraft engine of World War II. It was the direct competitor to the famous Daimler-Benz DB 601 and closely paralleled its development. While the Daimler-Benz engine was mostly used in fighters and destroyers, the Jumo engine was primarily used in bombers such as Junkers' own Ju 87 and Ju 88.

Design and development

The Jumo 211 was developed by Dr. Neugebauer as scaled-up successor to the earlier Jumo 210. In 1934, even before the new Jumo 210 had completed its acceptance tests, the RLM sent out a request for a new 1,000 hp-class engine of about 500 kg weight. Both Jumo and Daimler-Benz responded, and in order to reach service before the new Daimler-Benz DB 600, the Jumo team decided to make their new design as similar as possible to their 210H model, currently in testing.

The resulting Jumo 211 was first prototyped at Jumo's Dessau plant in 1935 and started testing in April 1936. Like the 210H, it featured a direct fuel injection system powered by small pistons driven off the crankshaft, three valves per cylinder, and an inverted V layout. Limited production of the 1,100 hp Jumo 211A started in April 1937 at Dessau, with just over 1,000 completed before full production was started at Magdeburg in July. Three models were provided with varied settings for its two-speed supercharger, tuned for different low- "versus" high-altitude performance. The first aircraft powered by the 211A arrived that November.

But by this time the DB 600 had finally arrived. Unlike the 211, the 600 was an all-new design that introduced a number of new features. Notably, it used a pressurized water cooling system that allowed it to use much less water inside the engine, and resulted in a smaller and lighter engine and radiator. Additionally, the higher pressures allowed the water to remain a liquid at all altitudes, allowing it to keep the engine cool at higher power settings. The 211's unpressurized cooling system had to lower the temperature of the coolant as the aircraft climbed in altitude and the boiling point dropped. Combined with a more powerful supercharger, the 600 was able to outperform the 211 at medium and high altitudes, relegating the 211 to lower altitude roles. Although many designs had already been drawn up using the 211, including fighters like the Bf 109 and Bf 110, these quickly moved to the 600 (and later the DB 601). The 211 became the major bomber engine of the war, in no small part due to Junkers also building most of the bombers then in use.

Development of the 211 continued with the 211B being released in 1938, with a slightly increased maximum RPM of 2,400 which boosted power to 1,200 hp. The later 211C and 211D differed primarily in the propeller gear ratios and other features.

A major upgrade was started in 1940 in order to better compete with the 601, following in its footsteps with a pressurized cooling system. The resulting 211E proved to be able to run at much higher power settings without overheating, so it was quickly followed by the 211F which included a strengthened crankshaft and a more efficient supercharger. Running at 2,600 RPM the F and similar J engines delivered a much improved 1,350 hp. Further improvements to this basic line led to the 1,425 hp 211N and 1,475 hp 211P. Continued development of the 211 line ended in favor of the re-named 213.

Total production of the 211 series amounted to 68,248 engines with a production peak of 1700 engines per month in the autumn of 1942.

Variants

* Jumo 211 A
* Jumo 211 Ba
* Jumo 211 Da
* Jumo 211 H, G
* Jumo 211 F (L, M, R)
* Jumo 211 J
* Jumo 211 N
* Jumo 211 P
* Jumo 211 Q

pecifications (Jumo 211 C)

pistonspecs

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type=Twelve-cylinder supercharged liquid-cooled 60-degree inverted V piston aircraft engine
bore=150 mm (5.91 in)
stroke=165 mm (6.5 in)
displacement=34.99 l (2,135.2 in³)
length=1,768 mm (69.61 in)
diameter=
width=804 mm (31.65 in)
height=1,050 mm (41.34 in)
weight=585 kg (1,290 lb)
valvetrain=Overhead camshafts
supercharger=Two-speed centrifugal type supercharger with automatic boost control
turbocharger=
fuelsystem=Carburetor
fueltype=87 octane rating gasoline
oilsystem=
coolingsystem=Liquid-cooled, ethylene glycol
power=
* 736 kW (1,000 PS or 986 hp) at 2,200 rpm for takeoff
* 754 kW (1,025 PS or 1,011 hp) at 2,200 rpm at 1,710 m (5,610 ft), first supercharger speed (bmep = 172.5psi)
* 718 kW (975 PS or 962 hp) at 2,200 rpm at 4,200 m (13,780 ft), second supercharger speed
specpower=21.54 kW/l (0.47 hp/in³)
compression=6.5:1
fuelcon=
specfuelcon=322-335 g/(kW•h) (0.53-0.55 lb/(hp•h))
oilcon=11-16 g/(kW•h) (0.28-0.42 oz/(hp•h))
power/weight=1.29 kW/kg (0.78 hp/lb)
reduction_gear=Spur, 1.55:1

Applications

*Avia S-199
*Focke-Wulf Ta 154
*Heinkel He 111
*IAR 79
*Junkers Ju 87
*Junkers Ju 88
*Savoia-Marchetti SM.79

ee Also

*Jumo 213

References

* "Jane's Fighting Aircraft of World War II". London. Studio Editions Ltd, 1989. ISBN 0-517-67964-7

External links

* [http://www.adressa.no/bildegallerier/article.jhtml?articleID=509630 Photos of two Jumo 211A engines raised from Lake Jonsvatnet, Trondheim, Norway, in 2004] (Adresseavisen)