| Jumo 211 | |
|---|---|
| Jumo 211D engine, mounted upside-down in this photo | |
| Type | Piston V-12 aero-engine |
| Manufacturer | Junkers |
| First run | 1936 |
| Major applications | Junkers Ju 87 Junkers Ju 88 |
| Number built | 68,248[1] |
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 single-engined and twin-engined fighters, the Jumo engine was primarily used in bombers such as Junkers' own Ju 87 and Ju 88.
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The Jumo 211 was developed by Dr. Franz Josef 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 PS-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 1,000 PS 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 Messerschmitt Bf 109 and Bf 110, these retained the Jumo 210 and moved to the DB 601 once it was available. The 211 became the major bomber engine of the war, in no small part due to Junkers also building a majority 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 PS. 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 211F delivered 1,340 PS and the 211J (a 211F with intercooler) delivered 1,420 PS. Further improvements to this basic line led to the 1,450 PS 211N and 1,500 PS 211P. Continued development of the 211 line evolved into the 213.
Total production of the 211 series amounted to 68,248 engines, including 1,046 prototypes and development engines, with a production peak of 1700 engines per month in the autumn of 1942. From 1937 to mid-1944, production was spread between factories in Magdeburg, Köthen, Leipzig, Stettin and Strassburg.[1]
Powers and rotational speeds are for take-off at sealevel.[1]
| Engine model | Power in PS | Power in hp | Power in kW | power at rpm |
|---|---|---|---|---|
| A (early) | 1,000 | 986 | 736 | 2,200 |
| A (late) | 1,100 | 1,085 | 809 | 2,300 |
| B,C,D,H,G | 1,200 | 1,184 | 883 | 2,400 |
| F,L,M,R | 1,340 | 1,322 | 986 | 2,600 |
| J | 1,420 | 1,401 | 1,044 | 2,600 |
| N | 1,450 | 1,430 | 1,067 | 2,700 |
| P | 1,500 | 1,479 | 1,103 | 2,700 |
Data from [2]
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