Junkers Ju 87 the opening day of the offensive, Hans-Ulrich Rudel flew the only "official" Ju 87 G, although a significant number of Ju 87D variants were fitted with the 37 mm (1.46 in) cannon, and operated as unofficial Ju 87 Gs before the battle. In June 1943, the RLM ordered 20 Ju 87Gs as production variants. The G-1 later influenced the design of the Fairchild Republic A-10 Thunderbolt II, with Hans Rudel's book, "Stuka Pilot" being required reading for all members of the A-X project. The Soviet Air Force practice of harassing German ground forces using antiquated Polikarpov Po-2 and R-5 biplanes
Junkers Ju 87 Secretary of State for Aviation Erhard Milch, feared that such high-level nerves and skill could not be expected of "average pilots" in the "Luftwaffe". Nevertheless, development continued at Junkers. Udet's "growing love affair" with the dive bomber pushed it to the forefront of German aviation development. Udet went so far as to advocate that all medium bombers should have dive-bombing capabilities, which initially doomed the only dedicated, strategic heavy bomber design to enter German front-line service during the war years — the 30-metre wingspan He 177A — into having an airframe design (due to Udet examining its design details in