Junkers Ju 87 armoured protection of the Ilyushin Il-2 "Sturmovik" - a feature pioneered by the 1916-17 origin Junkers J.I all-metal sesquiplane of World War I Imperial Germany's Luftstreitkräfte - was copied to protect the crew from ground fire now that the Ju 87 would be required to conduct low level attacks. Hans-Ulrich Rudel, a Stuka ace, had suggested using two 37 mm (1.46 in) Flak 18 guns, each one in a self-contained under-wing gun pod, as the "Bordkanone BK 3,7", after achieving success against Soviet tanks with the 20 mm MG 151/20 cannon. These gun pods were fitted to a Ju 87
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