In 1942, the Luftwaffe command realized the insufficient effectiveness of standard bombs against the ever-increasing tank armor. And if at the beginning of the war the effectiveness of conventional bombs was quite acceptable, then by the beginning of 1943 they were practically useless against the growing number of T-34 medium tanks. A direct hit of the bomb on the tank was necessary. But diving into each individual tank with a 250-kg bomb was not possible. There aren't enough bombs, and it's hard to hit. It was necessary to counter the emerging threat with some new, more advanced weapon. It was proposed to use the upgraded 37-mm Flak 18 anti-aircraft gun in this capacity. Alteration of the gun was reduced to changing the muzzle brake, reducing the barrel length and changing the recoil and bolt mechanisms. The whole structure was placed in a streamlined container. So the VK 3.7 sm aircraft gun was born. The ammunition load of the gun was 12 shells (usually armor-piercing) in narrow box magazines.
Only two modifications of the Stuka received this anti-tank weapon - the Ju 87G-1, converted from the D-3 (about 100 copies were produced in total) and the Ju 87G-2, created on the basis of the D-5 (174 vehicles). On some "Gustavs" they retained the usual offensive weapons, which were used for sighting.
In December 1942, the new version was tested at the Rechlin training ground and ... were satisfied. No one really bothered to answer the question of how the Gustav pilot should fight in a car, under the wing of which bulky pieces of iron stick out, each of which weighed more than 300 kg. The new attack aircraft had such a low speed that it barely overtook the old reconnaissance aircraft Hs 126, contemptuously referred to in the Red Army as a “crutch”, the new Ju 87 also earned many nicknames: “Cannon bird” (Kanonenvogel) or “Thing with long sticks” (Stuka mil den Langen Stangen).