An armoured bath with wings, built in greater numbers than any other military aircraft in history.
1941·Il-2M3·410 km/h·36,183·Mikulin AM-38F V-12, 1,720 hp·5 to 12 mm, ~700 kg·AM-38, 1,600 hp, 455 km/h
1· THE STORY
A bath of steel with wings
The Il-2 went into action in the first weeks after Germany invaded the Soviet Union in June 1941, and the Red Army never had enough of them. It was built around a bath of armour plate that carried the engine, the fuel, the radiators and the pilot inside it, and it flew at tree-top height straight into the flak, firing cannon and rockets and dropping bombs on tanks. Stalin told the factories it was as necessary to the army as bread. More than 36,000 were built, and around 10,000 were lost — it was hard to kill, not impossible.
410 km/hTop speed (M3)36,183Built (all versions)
2· WHY IT MATTERED
Armour as structure
Most aircraft bolt armour plate onto a light frame. The Il-2’s forward fuselage was the armour: a welded shell of 5 to 12 mm steel weighing about 700 kg, roughly a seventh of the aircraft, that was the structure. It shrugged off rifle-calibre bullets and shell fragments that would have finished a fighter; a 20 mm hit was another matter, and the bath was never proof against one. The gunner, added back in 1942 after single-seaters were slaughtered from behind, sat outside the bath with far less protection and was killed or wounded several times as often as the pilot in front of him.
At Kursk in 1943 the Il-2 opened four containers under its wings and let go of 192 small shaped-charge bombs, each 2.5 kg, that fell in a strip a few hundred metres long. No precise aiming was needed: a tank inside the strip stood a fair chance of a hit or two on its thin engine deck, which a shaped charge that small could still burn through. How many were really knocked out is argued over; dispersion, duds and overlapping strips all mattered.
4· WHY IT MATTERED
Built for one height
Everything about the Il-2 was tuned to the fifty metres above the battlefield. Its engine was geared for low altitude, its guns were for soft vehicles and its armour faced the ground. Its service ceiling, about 4,500 m for the loaded two-seater, would have been useless in the West; in the East nobody needed it.
5· THE ENGINE
The biggest V-12 of the ten, geared for tree-top height
The AM-38 was a fighter engine, the AM-35, deliberately made worse at altitude: its supercharger was geared down so that all of its air went in at low level, and its compression ratio was dropped to six to one so that it ran without knocking on the Soviet 78-octane grade the front actually had. At 46.7 litres it was the largest engine in this list, heavy and cheap, with a ten-minute emergency rating the pilots used to get over the last line of flak. Forty-three thousand were built.
Il-2 (1941): Mikulin AM-38 · V-12 · 46.7 L · single-speed supercharger geared for low altitude · 1,600 hp boosted · Il-2M (1942) and M3 (1943): AM-38F, 1,720 hp take-off, 1,500 hp at 750 m
Two 23 mm cannon and two of the fastest-firing machine guns of the war put about 4.6 kg of metal a second into whatever was ahead, for fifteen seconds of cannon fire. Under the wings hung rockets or bombs; from 1943 the four containers of PTAB shaped-charge bomblets were the weapon that mattered. None of it was accurate by modern standards. Numbers were.
7· TRY IT
An engine that only breathes low down
The lab runs the AM-38F against altitude: enormous power at the height of the battlefield and a curve that collapses above 2,000 m. Switch on the Spitfire Mk I’s Merlin III for comparison and the reason for the Il-2’s low ceiling is on the chart.
At 1,500 m: 1,585 hp in total, true airspeed 410 km/h.
Readout
Power1,585 hp
Per engine1,585 hp
True airspeed410 km/h
Service ceiling4,525 m
A simplified model calibrated to the published rating and top speed — the shape of the curve is the point, not the third decimal.
Ilyushin Il-2 Shturmovik, 4 of 10
Deep dive · The armoured bath· opened from Ilyushin Il-2 Shturmovik
Seven hundred kilograms of steel that was the aircraft, not bolted onto it.
5–12 mm AB-1 steel·~700 kg·36,183·~10,700
01The idea
A welded shell of 5–12 mm armour steel around engine, fuel, radiators and pilot
Armour is heavy, and an aircraft that carries it as dead weight bolted to a light frame pays for it twice: once in the plate and once in the frame that holds the plate. Ilyushin’s answer was to make the armour the frame. The forward fuselage of the Il-2 was a bath of welded armour steel, 5 mm on the sides and up to 12 mm where the fire came from, and the engine, the fuel tanks, the radiators and the pilot sat inside it. It weighed about 700 kg, and it was the reason an aircraft slower than everything that shot at it kept coming back.
02Why it matters
Where the plate is thick
Ground fire arrives from below and ahead, at a shallow angle. Plate met at a glancing angle behaves as if it were thicker — a 20 mm shell hitting 8 mm of steel at 60° has to get through about 16 mm of it. The bath was thickest where the geometry could not help and thinnest on top, where nothing much arrived.
03Why it matters
The gunner outside the bath
The first production Il-2 was a single-seater, the gunner’s position having been deleted to save weight, and German fighters killed it from behind at will. The gunner came back in 1942, sitting behind the bath with a heavy machine gun and a sheet of thin plate, and was killed or wounded several times as often as the pilot in front of him.
04Why it matters
Hard to kill is not impossible
More than ten thousand Il-2s were lost, a third of those built. Flak, fighters and the ground itself took them; the rear fuselage was often wood and burned. What the bath bought was not invulnerability but survival often enough for numbers to matter, and the Soviet Union built numbers.
05Try it
Plate at an angle
Tilt the plate and see how much steel a shell has to pass through.
Readout
Steel on the path8.5 mm
Times the plate× 1.41
At this anglehas to punch through
Geometry only. A 20 mm armour-piercing round from a fighter defeated roughly its own calibre of plate at right angles and close range; the Il-2’s 5–12 mm sides, sloped, were meant to be more than that on the paths that mattered.