The Jumo 204 was an opposed-piston , inline, liquid-cooled 6-cylinder aircraft Diesel engine produced by the German manufacturer Junkers . It entered service in 1932. Later engines in the series, the Jumo 205 , Jumo 206 , Jumo 207 and Jumo 208 , differed in stroke, bore, and supercharging arrangements.
6-626: The Napier Culverin was a licensed built version of the Junkers Jumo 204 six-cylinder vertically opposed liquid-cooled diesel aircraft engine built by D. Napier & Son . The name is derived from the French word, culverin , for an early cannon or musket. First flown in 1938, the engine went into limited production, with testing carried out on a Blackburn Iris V biplane flying-boat aircraft and Fairey IIIF biplane. The six cylinders were arranged vertically. Two crankshafts were located at
12-459: Is typical of two-stroke designs, the Jumos used fixed intake and exhaust ports instead of valves, which were uncovered when the pistons reached a certain point in their stroke. Normally such designs have poor volumetric efficiency because both ports open and close at the same time and are generally located across from each other in the cylinder. This leads to poor scavenging of the burnt charge, which
18-419: Is why valve-less two-strokes generally run smoky and are inefficient. The Jumo 204 solved this problem to a very large degree through a better arrangement of the ports. The intake port was located under the "lower" piston, while the exhaust port was under the "upper". The lower crankshaft ran eleven degrees behind the upper, meaning that the exhaust ports opened first, allowing proper scavenging. This system made
24-602: The Reichsluftfahrtministerium (RLM), where the first number indicates the manufacturer; 2 – Junkers Motoren. These engines used a two-stroke cycle with six cylinders and twelve pistons, in an opposed piston configuration with two crankshafts, one at the bottom of the cylinder block and the other at the top, geared together. The pistons moved towards each other during the operating cycle. There were two cam-operated injection pumps per cylinder, each feeding two nozzles, totaling four nozzles per cylinder. As
30-536: The top and bottom of the engine and coupled together by gears. The inlet and exhaust ports were controlled by the pistons, as in a petrol-fuelled two-stroke engine . Data from Junkers Jumo 204 Development of the Junkers diesel engines started in the 1920s with the Junkers Fo3 and Junkers Fo4 / Junkers SL1 . The Fo4 was re-designated Junkers 4 , which in turn was re-designated Junkers Jumo 204 by
36-465: The two-stroke Jumos run as cleanly as four-stroke engines using valves, but with considerably less complexity. The Jumo 204 (originally designated Jumo 4 ) was test flown in early 1929 installed in a Junkers G 24 . The Jumo Fo3 and 204 were licensed to Napier & Son , who built a small number as the Napier Culverin just prior to the war. Late in the war, they mounted three Culverins in
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