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 aircraft engines, albeit in the absence of its founder, who had been removed by the Nazis in 1934. The history of Junkers aircraft production begins with the Junkers J 1 mid-wing monoplane (not to be confused with the later, all-metal sesquiplane ground attack aircraft with the "IdFlieg" designation J.I which had a factory designation of J 4). Research for this aircraft began in 1914 and was interrupted by the start of the First World War. The prototype aircraft, named the "Blechesel" (Tin or Sheet-metal Donkey), was completed in very late 1915 after the outbreak of the war. This aircraft is