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 J 2 fuselage framing, primarily as an engineering exercise, were finished shortly before the end of 1916. It is also thought that the contrasting promise of the advanced, low drag features of the Junkers monoplane aircraft designs, versus the Junkers firm's usage of experimental non-traditional sheet metal materials, and the firm's habit of almost constant experimentation obstructing any future hope of producing its advanced designs for the "Luftstreitkräfte", compelled "IdFlieg" to create the "Junkers-Fokker Aktiengesellschaft", abbreviated as "Jfa" and pronounced as if spelled "iefa" in German, on 20 October 1917, to allow Anthony Fokker, who even flew one of the J 2