On 21st July 1941 the lead designer of the IL-2 Sergey Ilyushin sent a request to the People's Minister of Aviation, calling for improvement of the IL-2 by upgrading the engine to a 1,675-HP M-82 and increasing the aircraft's armour. The request was extremely urgent, considering that the rapidly advancing German troops at the time threatened serial production of the engines then used on the IL-2. Several influential Party members also called for upgrading the IL-2's engine. Another crucial change, in conjunction with the engine, called for converting the aircraft into a two-seater, based on combat experience. The second crewman would mainly deal with protecting the rear section of the Sturmovik from aerial attack, making it, in the designer's opinion, "nearly invincible". An aft fuel tank, previously installed behind the pilot in the armoured tub, was replaced with a gunner compartment under a stretched canopy, armed with a 12.7mm (.50-cal) UBT machine gun with 280 rounds of ammunition. The gunner position, just like the pilot's, was well armoured.
Once the prototype was tested, all test pilots concluded that flight performance of the new variant was worse than that of the earlier IL-2 AM-38 variant; however no changes in overall behaviour were noted, the armour was very effective, and no shortcomings that made flying dangerous were uncovered. Therefore, the new prototype was accepted for serial production.