By early 1943 the Luftwaffe, or rather the whole German army at the Eastern Front, faced a critical problem fighting Soviet armoured forces. The equipment intended to stop the "Russian steam roller" included a special anti-tank version of the Stuka that appeared in late 1943.
The first anti-tank variant, the Ju.87G-1, was based on the Ju.87D-3 variant. The main distinction of the G-1 was that it had two containers fitted under the wings to house 37 mm Bordkanone BK 3.7 cannons (an airborne version of the Rheinmetall Flak 18 anti-aircraft gun), with 6 rounds each. The shells were kept in magazines protruding beyond the sides of the container. The long-barrelled anti-aircraft gun brought the tungsten-core sabots to an initial velocity of 1,170 m/s, allowing the gun to be fired at a distance of about 800 m. This was quite sufficient to pierce the rear or upper plating of the T-34 tank.
When D-3s were converted to G-1s, the wing-mounted machine guns and the bomb racks were removed. The aircraft's armour was weakened. Unlike those on the standard Ju.87D-3, the radio operator/gunner's station, the fuel tanks in the centre wing section, and the radiator were not armoured on the anti-aircraft Stuka.
Tests showed that the Ju.87G-1's speed was reduced by 30-40 km/h and its maneuverability was noticeably impaired, which, in addition to its weakened armour and poor defensive armament, made the machine almost a perfect target for fighter attacks. Due to the aircraft's poor longitudinal stability, it was difficult to aim. The BK 3.7 cannon had quite a low rate of fire and a low reliability as far as its automatic equipment was concerned. In fact, for a Ju.87G, success on the battlefield was possible only if it was flown by an experienced pilot and only if enemy anti-aircraft gunners and fighters provided little opposition.
However, if operated by an experienced gunner, the Gustav was able to hit the tank's most vulnerable parts, such as its engines, fuel tanks, and ammunition stowage bins. This was the reason why the Ju.87G-1's tests were considered successful, and the military came to the conclusion that the prospect of its use in combat was reasonable, since the situation was hopeless otherwise, as there were no other aircraft anywhere near suitable for fighting tanks.
Production Ju.87D-3s were converted to G-1s on site by the troops. For this conversion, the cannon-housing containers could be easily removed and replaced with standard bomb racks. None of the aircraft had dive flaps, but the brackets to fit them remained. A total of about 40 machines were converted in this fashion.