Junkers Jumo 211

Junkers Motoren

Industry	Aero engine manufacturing
Founded	1935
Headquarters	Dessau, Magdeburg , Germany
Products	Jumo 211 aircraft engine

The Jumo 211 was an inverted V-12 aircraft powerplant developed in Germany and served as Junkers Motoren's principal aero engine throughout World War II. It was designed as a direct rival to the Daimler-Benz DB 601, with both engines evolving along similar timelines. Whereas the Daimler-Benz unit was predominantly installed in single- and twin-engine fighter aircraft, the Jumo 211 found its main application in bombers, including Junkers' own Ju 87 and Ju 88, as well as Heinkel's H-series variants of the Heinkel He 111 medium bomber. It holds the distinction of being the most extensively produced German aircraft engine during the conflict, with nearly 70,000 units manufactured.

Design and development

Conceived by Dr. Franz Josef Neugebauer, the Jumo 211 was an enlarged evolution of the earlier Jumo 210. The Jumo 210 represented Germany’s first contemporary aviation engine, featuring three valves per cylinder, a cast crankcase, and a standard supercharger. When introduced in the early 1930s, its output of approximately 700 PS was typical for the era, serving as a foundational powerplant for many pre-war German designs. Progressing through development, the 210G variant incorporated piston-driven direct fuel injection, enabling it to fully realize its performance potential.

During the rapid advancement of aircraft capabilities and size throughout the 1930s, a new demand emerged. In 1934, prior to completion of acceptance testing for the Jumo 210, the RLM issued a requirement for a new engine delivering around 1,000 metric horsepower (740 kW) and weighing close to 500 kg (1,100 lb). Both Junkers and Daimler-Benz submitted proposals. To expedite deployment ahead of the forthcoming Daimler-Benz DB 600, Junkers opted to base their new design closely on the then-experimental 210H model.

The Jumo 211 prototype was constructed at Junkers’ Dessau facility in 1935 and commenced testing by April 1936. Retaining features from the 210H, it employed a mechanical direct fuel injection system actuated by small pistons linked to the crankshaft, three valves per cylinder, and an inverted V configuration. Its cooling system operated on an open cycle at atmospheric pressure. Limited production of the initial Jumo 211A variant began in April 1937 at Dessau, yielding just over a thousand units before full-scale manufacturing shifted to Magdeburg in July.

Three distinct variants were offered with different settings for their two-speed supercharger, optimized for performance variations between low and high altitudes. The first aircraft equipped with the Jumo 211A prototype appeared by late 1937. Development progressed with the 211B model released in 1938, featuring an increased maximum RPM of 2,400 that raised output to approximately 1,200 PS (1,184 HP). Subsequent versions 211C and 211D mainly differed in propeller gear ratios and additional refinements.

File:Junkers Jumo 211BD.JPG

Junkers Jumo 211B/D engine displayed at the Luftwaffenmuseum der Bundeswehr

The Daimler-Benz DB 600 shared many design elements but initially lacked direct fuel injection. Following RLM directives mandating this feature for all future engines, Daimler introduced the DB 601 in late 1937 incorporating mechanical direct injection.

In 1940, Junkers initiated a significant upgrade by integrating a pressurized cooling system into the Jumo 211. Pressurizing increased water’s boiling point, permitting higher operating temperatures and enabling more heat energy to be dissipated with less coolant volume. This advancement allowed elevated power outputs while utilizing smaller radiators. The 211E variant demonstrated enhanced tolerance for higher power settings without overheating and was succeeded swiftly by the 211F, which included a reinforced crankshaft and an improved supercharger. Operating at up to 2,600 RPM, the 211F delivered 1,340 metric horsepower (990 kW), while the 211J—a 211F equipped with an intercooler—produced 1,420 metric horsepower (1,040 kW). Further refinements yielded the 1,450 metric horsepower (1,070 kW) 211N and 1,500 metric horsepower (1,100 kW) 211P models by 1943; these maintained similar configurations to the F/J series but featured slight increases in boost pressure and ran up to 2,700 RPM. The ongoing evolution of this engine family culminated in development of the Jumo 213.

File:Bundesarchiv Bild 146-1989-039-16A, Schwerer Bomber Me 264.jpg

The Me 264 V1 Amerika Bomber contender equipped with four unitized Jumo 211 engines identical to those used on Ju 88As

Throughout World War II, the Jumo 211 emerged as a principal bomber engine largely due to Junkers producing many of Germany’s frontline bombers. Although final engine selections were made by Luftwaffe authorities after competitive evaluations involving prototypes such as the Dornier Do 217, several factors influenced widespread adoption: limited manufacturing capacity for each type; suitability of the Jumo for bomber installations; and its competitive or superior performance characteristics compared to alternatives. The Daimler-Benz engines held advantages in lightweight single-engine fighters, leaving bombers primarily powered by Jumo units. Nevertheless, demand eventually exceeded supply capacity for both inline engines leading to increased deployment of radial engines like the BMW 801, often alongside Jumo and Daimler-Benz powerplants in multi-engine configurations.

Cumulative production of all Jumo 211 variants reached approximately 68,248 units—including over one thousand prototypes and developmental engines—with peak output hitting around seventeen hundred engines monthly during autumn of 1942. Between initial production in 1937 through mid-1944 manufacturing took place at facilities located in Magdeburg, Köthen, Leipzig, Stettin, and Strasburg. This made it Germany’s most-produced aero engine during World War II and likely one of the first German aviation engines adapted into a Kraftei modular "power egg" format—pre-packaged units exemplified by those used on Ju 88A aircraft were also installed on experimental platforms such as the Messerschmitt Me 264 V1 competing for the Amerika Bomber contract in December 1942.

Variants

The power outputs and rotational speeds listed correspond to take-off conditions at sea level.

Engine variant	Power (PS)	Power (hp)	Power (kW)	RPM at power
A (initial)	1,000	986	736	2,200
A (later)	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

Applications

• Avia S-199
• Dornier Do 217 – utilized as a single-engine test platform
• Focke-Wulf Ta 154
• Heinkel He 111E, H and Z variants
• IAR 79
• Junkers F 24 – served as a testbed for the Jumo 211 engine
• Junkers Ju 87
• Junkers Ju 88
• Junkers Ju 90
• Junkers Ju 252
• Messerschmitt Me 264 (only the V1 prototype equipped; later replaced by four BMW 801 engines)
• Messerschmitt Me 323 (used solely for testing purposes)
• Savoia-Marchetti SM.79 (Romanian-produced versions)

Specifications (Jumo 211Ba / 211Da)

File:Jumo 211F front.jpg

Jumo 211F

External links

• Photographs of two Jumo 211A engines recovered from Lake Jonsvatnet, Trondheim, Norway, in 2004 (Adresseavisen)
• Illustration from the UK Flight Magazine, mid-November 1939, depicting the Kraftei-integrated Jumo 211 featuring an annular radiator, as installed on the Ju 88A