The original Il-2 had no rear gun position. However the plane was structally armoured (as opposed to armour added) which carried major parts of the structural functions. Armour was in pilot cockpit, engine, cooling system and internal bomb bays. The armour could withstand much ground fire allowing the pilots more time aiming while over target.
The plane could dogfight but lack of pilot training led to many losses as lessons had to be learnt on the battlefield. Experience is a hard teacher, it gives the test then teaches later.
In 1942 the Il-2 got its rear gun position in the IL-2M. Although before that some improvised adopting turrets from such planes as the old R-5. The gunner position was not armoured so life expectancy was 7 times less of that of the pilot, or plane.
The Il-2 Type 3 was further improved, making a more stable plane by reshaping the wings. As pilot skill improved and new tactics evolved the losses began to drop, and in 1943 only 2.8% IL-2s were lost during missions, with 50% coming home damaged. 90% were repaired at the front because of the simple design.
Some ground crews even complained because holes were sometimes 1 metre square, and that they could not repair it. 1 METRE SQUARE!!! No other plane was complained about like that.
36,163 were produced, maybe the biggest production run in history.
Il-2 Armament - 2*20mm ShVAK 500/gun
2*7.62mm ShKAS 700/gun
Bombs- 400 kg
Rockets - 8*RS-82mm or
8* RS-132mm
Il-2M - 2*20mm ShVAK 500/gun
or 2*23mm VYa 300/gun
2* 7.62mm ShKAS
Rear Defence - 12.7mm UBT
Bombs - 400 kg
Rockets- 4* RS-82mm or
4* RS-132mm
Il-2 Type 3 - 2*23mm VYa
2* 7.62mm ShKAS
Rear Defence- 12.7mm UBT
Bombs - 750kg
Rockets- 4* RS-82mm
or 4* RS-132mm
Il-2 Type 3M - 2*37mm NS-37
2* 7.62mm ShKAS
Rear Defence - 12.7mm UBT
Bombs - 600kg
Rockets- 4*RS-82mm or
4* RS-132mm
Those being standard armaments, other variation of armament include the rear-ward firing grenade launcher DAG-10 and 4 containers of 192 PTAB each.
That ladies and gentlemen is why the IL-2 Sturmovik aka. Concrete Plane is the greatest tank destroyer of World War 2. So there.
Needed that.