Most armoured aircraft of the era carried protection as dead weight — plates added on top of a conventional structure. Ilyushin inverted the idea. The Il-2’s forward fuselage was a single moulded shell of hardened steel, commonly cited between roughly 4 and 12 mm thick depending on location, that enclosed the Mikulin engine, the radiators, the fuel and the pilot, and simultaneously served as primary structure. Because the armour did double duty as skin and frame, the aircraft carried far more protection for a given weight penalty than a bolt-on scheme would allow — commonly cited at several hundred kilograms of steel.

The trade-off was performance: the Il-2 was heavy, and never fast or agile. But over the battlefield that mattered less than survivability. Returning Sturmoviks were routinely counted with dozens of hits, and accounts describe individual aircraft absorbing very large numbers of strikes and still flying home — figures that should be read as illustrative of its reputation for toughness rather than precise engineering data.

The PTAB (protivotankovaya aviabomba) was a small shaped-charge bomblet weighing about 1.5 kg. A single Il-2 could carry hundreds of them in its bomb bays and scatter them across an area, so that even near-misses could pierce the thinner armour on a tank’s engine deck and turret roof. First used in strength at the Battle of Kursk in July 1943, they let the Sturmovik attack massed armour far more effectively than free-fall bombs or cannon alone. Il-2 units also flew the “krug smerti” or circle of death — a rotating wheel of aircraft in which each covered the tail of the one ahead while taking turns to dive on the target. Soviet claims of tanks destroyed at Kursk were very high and are now regarded by historians as inflated, but the psychological and disruptive effect on German armour was real.

To wring more speed and range out of the design, the Il-2 entered service as a single-seater. It was well protected from the front and below, but had nothing covering its tail — and German fighter pilots soon learned to attack from behind and slightly below, into the aircraft’s blind spot. Loss rates in 1941–42 were punishing. The fix was to restore the rear gunner that early prototypes had carried, armed with a 12.7 mm UBT machine gun, from late 1942. The gunner sat behind the armoured tub with much less protection than the pilot, and gunner casualties were heavy — but the two-seat Il-2 could finally defend its tail, and survivability improved markedly.

The Il-2 was a wartime Soviet state product, built to a planned economy’s output targets rather than sold on an open market, so there is no meaningful flyaway dollar price or cost-per-flight-hour figure for it. What the record does make clear is that it was designed to be cheap and fast to build — using wood in the rear fuselage and outer wings to spare scarce aluminium, and simple enough that factories could turn out thousands per month at the production peak. That affordability, as much as its armour, is why roughly 36,000 were built. Any precise cost figure attached to the type should be treated as an estimate.