The armor did not provide the IL-2 a reliable protection against neither large-caliber bullets nor anti-aircraft artillery shells. The only advantage of armor was better pilot survivability during emergency landings.
The distribution of armor thickness was not optimal, there were areas where there were no hits at all and vice versa, areas with a high percentage of hits had insufficient armor. Nearly every penetration of the cowl armor resulted in engine damage. Only the lower cowl armor provided sufficient protection.
In general, the IL-2 concept was very controversial - it was a bad idea to use a liquid-cooled engine on an attack aircraft. The result was a heavy, poorly maneuverable and rather vulnerable aircraft. I have to repeat: under the same conditions, obsolete fighters without armor used for ground attack suffered many times fewer losses. Yes, they were not as well armed as the Il, but nevertheless they could be very effective (for example, the I-207, which was not built in series, was highly appreciated). They also did not use the high-octane gasoline that the IL-2 required. There were other alternatives, starting with the very promising Vultee A-11.
The whole story of Soviet attack aircraft development is a clear illustration of the total inefficiency of the Soviet system.
The distribution of armor thickness was not optimal, there were areas where there were no hits at all and vice versa, areas with a high percentage of hits had insufficient armor. Nearly every penetration of the cowl armor resulted in engine damage. Only the lower cowl armor provided sufficient protection.
In general, the IL-2 concept was very controversial - it was a bad idea to use a liquid-cooled engine on an attack aircraft. The result was a heavy, poorly maneuverable and rather vulnerable aircraft. I have to repeat: under the same conditions, obsolete fighters without armor used for ground attack suffered many times fewer losses. Yes, they were not as well armed as the Il, but nevertheless they could be very effective (for example, the I-207, which was not built in series, was highly appreciated). They also did not use the high-octane gasoline that the IL-2 required. There were other alternatives, starting with the very promising Vultee A-11.
The whole story of Soviet attack aircraft development is a clear illustration of the total inefficiency of the Soviet system.