Junkers Jumo 211
|Jumo 211D engine, mounted upside-down in this photo|
|Type||Piston V-12 aero-engine|
|Major applications||Avia S-199
Heinkel He 111H
Junkers Ju 87B-G
Junkers Ju 88A/C
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, and Heinkel's H-series examples of the Heinkel He 111 medium bomber. It was the most-produced German aero engine of the war, with almost 70,000 examples completed.
Design and development
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 mechanical direct fuel injection system using small pistons driven off the crankshaft, three valves per cylinder, and an inverted V layout. It also had an open-cycle cooling system, not pressurized, as was the case on the later 213. Limited production of the 1,000 PS (990 hp; 740 kW) 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 prototype aircraft powered by the 211A appeared in late 1937.
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 1200 PS (1184 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 211F delivered 1,340 PS (1,320 hp; 990 kW) and the 211J (a 211F with intercooler) 1,420 PS (1,400 hp; 1,040 kW). Further improvements to this basic line led to the 1,450 PS (1,430 hp; 1,070 kW) 211N and 1,500 PS (1,500 hp; 1,100 kW) 211P in 1943, they were equivalent to the 211F/J but with slight boost increases and running at up to 2,700 rpm. Continued development of the 211 line evolved into the Jumo 213.
The Jumo 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. Of course, since it was the Luftwaffe that selected the final engine to be used after competitive testing on prototypes (such as the Dornier Do 217), there is certainly more to it. Limited production capacity for each type, and the fact that the Jumo was perfectly capable (if not superior) in a bomber installation meant that it made sense to use both major types to the fullest; since the Daimler had a slight edge in a lightweight, single-engine application, that left the Jumo to fill in the remaining roles as a bomber engine. Even this wasn't enough in the end, and radial engines like the BMW 801 were increasingly put into service alongside the Jumo and DB series, most often in multi-engine installations like the Jumo. 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 Strasburg. It was the most-produced German aviation engine of the World War II years, and was quite likely to have been the first model of German aviation engine selected for "unitizing" as a Kraftei pre-packaged "engine module" — such Kraftei units for the Ju 88A were, as one example, used as the initial quartet of powerplants to power the Messerschmitt Me 264 V1 Amerika Bomber contract competitor into the air in December 1942.
Powers and rotational speeds are for take-off at sealevel.
|Engine model||Power in PS||Power in hp||Power in kW||power at rpm|
- Avia S-199
- Dornier Do 217 - single engine test aircraft
- Focke-Wulf Ta 154
- Heinkel He 111E, H and Z
- IAR 79
- Junkers F 24kai Jumo 211 test bed
- Junkers Ju 87
- Junkers Ju 88
- Junkers Ju 90
- Junkers Ju 252
- Messerschmitt Me 264 (V1 prototype only, replaced with four BMW 801s)
- Messerschmitt Me 323 (only for tests)
- Savoia-Marchetti SM.79 (Romanian variants)
Specifications (Jumo 211 C)
Data from 
- 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)
- Width: 804 mm (31.65 in)
- Height: 1,050 mm (41.34 in)
- Dry weight: 585 kg (1,290 lb)
- Valvetrain: Overhead camshaft, 3 valves per cylinder
- Supercharger: Two-speed centrifugal type supercharger with automatic boost control
- Fuel system: direct fuel injection
- Fuel type: 87 octane rating gasoline
- Cooling system: Liquid-cooled, ethylene glycol
- Reduction gear: Spur, 1.55:1
- Power output:
- 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
- 718 kW (975 PS or 962 hp) at 2,200 rpm at 4,200 m (13,780 ft), second supercharger speed
- Specific power: 21.54 kW/l (0.47 hp/in³)
- Compression ratio: 6.5:1
- Specific fuel consumption: 322-335 g/(kW•h) (0.53-0.55 lb/(hp•h))
- Oil consumption: 11-16 g/(kW•h) (0.28-0.42 oz/(hp•h))
- Power-to-weight ratio: 1.29 kW/kg (0.78 hp/lb)
- Kay, Antony (2004). Junkers Aircraft & engines 1913-1945. London: Putnam Aeronautical Books. pp. 271–2. ISBN 0-85177-985-9.
- Christopher, John. The Race for Hitler's X-Planes (The Mill, Gloucestershire: History Press, 2013), p.78.
- Tsygulev (1939). Aviacionnye motory voennykh vozdushnykh sil inostrannykh gosudarstv (Авиационные моторы военных воздушных сил иностранных государств) (in Russian). Moscow: Gosudarstvennoe voennoe izdatelstvo Narkomata Oborony Soyuza SSR. Archived from the original on 2009-03-24.
|Wikimedia Commons has media related to Junkers Jumo 211.|