Junkers setbacks with crashes of prototypes in 1937 and 1938. Further refinements enabled certification in 1939 and spurred South African Airways to make an initial order for two aircraft fitted with US-built Pratt & Whitney engines. Just as the aircraft was being readied for its first commercial flights, World War II began. With the outbreak of hostilities, all models were requisitioned by the Luftwaffe for military air-transport roles, and later, long-range maritime patrol. Military aircraft production was begun by the company in the 1930s and eventually monopolized all its resources. Perhaps the most notable design was the Junkers Ju 87 "Stuka"
Junkers described by a Ju number, e.g. Ju 21. Data from Kay, 2004, pp. 257–278 All Junkers diesel engines were two stroke, opposed piston designs, an arrangement he invented in the early 1890s. It was intended to provide an alternative to Nicholaus Otto's patented four stroke which would run on low grade fuels such as blast furnace waste gases. By 1896 Junkers engines were generating electrical power in steelworks. Junkers Junkers Flugzeug- und Motorenwerke AG (JFM, earlier JCO or JKO in World War I), more commonly Junkers, was a major German aircraft and aircraft engine manufacturer. It produced some of the