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Junkers Jumo 213The Jumo 213 was a World War II-era V-12 liquid cooled aircraft engine, a development of Junkers Motoren's earlier design, the Jumo 211. The design added two features, a pressurized cooling system that required considerably less cooling fluid that allowed the engine to be built smaller, and a number of improvements that allowed it to run at higher RPM. Although these changes sound fairly minor, they boosted power by over 500 hp, making it one of the most sought-after engine designs in the late-war era. When the Jumo 211 entered production in the late 1930s it used a normal liquid cooling system based on an "open cycle". Water was pumped through the engine to keep it cool, but the system as a whole operated at outside air pressure, or slightly greater. Since the boiling point of water is effected by pressure, this meant that as the aircraft climbed the temperature of the cooling water had to be kept quite low to avoid boiling. This meant that the water removed little heat from the engine before having to be move to the radiator to cool it. In contrast, the Daimler-Benz DB 601 used a pressurized system that ran at the same pressure at all altitudes, and actually had a boiling point of about 110C. This allowed it to use considerably less water, and the engine itself to be smaller. Although otherwise similar in most respects, the 601 was smaller and lighter than the 211, making it popular in fighter designs. The 211 was relegated to "secondary" roles in bombers and transports. Junkers was not happy with this state of affairs, and started their own efforts to produce a pressurized cooling system as early as 1938. Experiments on the 211 proved so successful that it became clear that not only could the engine be built smaller, but could be run at higher power settings without overheating. Additional changes to strengthen the crankshaft, add a fully-shrouded supercharger for increased boost resulted in the Jumo 211F model, which delivered 1,400 hp at 2,400 RPM, up from 950 hp at 2,200 RPM. But this was only the beginning. After redesigning the engine casing to a smaller size to suit the increased cooling power, increasing boost settings on the supercharger the new 213A model was able to deliver a whopping 1,750 PS (metric hp) at 3,250 RPM. Specifications - Configuration: Twelve-cylinder inverted-Vee liquid-cooled (pressurized water up to 120C)
- Bore by stroke: 150 by 165 mm
- Displacement: 35 litres
- Compression ratio: 6.5:1 (B4 fuel, 87 octane)
- Power: 1,750 PS (1287 kW) at 3,250 rpm for takeoff
- Supercharger: Two-stage (213A,C), three-stage two-speed (213E)
- Rated altitude: 6,000 m (213A,C), 9,600 m (213E)
- Dimensions: Length: 2.266 m
- Weight: 920 kg (213A,C), 940 kg (213E)
Jumo 213 versions - 213A: First version, 1,750 PS (2,100 PS with MW50 boost) take-off power
- 213B: Project, a 213A with C3 fuel (100 octane) and up to 2,000 PS take-off power
- 213C: Optimized 213A, re-arranging of secondary equipment allowed mounting of a cannon firing through the propeller axis
- 213E: High altitude version of 213A with 1,750 PS (2,050 PS with MW50 boost) take-off power
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