Junkers Ju 87 Stuka (1939): dive-bombing the Blitzkrieg

1939·410 km/h·up to 1,800 kg·Jumo 211J inverted V-12, 1,400 hp·1,535 km·~6,500

· THE STORY

Artillery that fell out of the sky

The Stuka is the sound of the first year of the war. In Poland, Norway and France it flew ahead of the tanks as artillery that could be anywhere in minutes: it rolled over, pointed its nose almost straight down at a bridge or a gun position, and released its bomb from a few hundred metres up. It was slow, and once the fighters it needed were gone it was shot out of the sky over England — but it fought to the last day in the East, and for one year it changed how wars were fought.

410 km/hTop speedup to 1,800 kgBomb load

· WHY IT MATTERED

Accuracy from a dive, not a bombsight

Level bombers of 1939 missed by hundreds of metres. A Stuka pilot lined the target up through red lines painted on his canopy at 60°, 75° and 80°, and dived at it: the bomb left the aircraft already pointed at the target, and hit within tens of metres. That is why a squadron of them could take out a bridge the whole artillery had missed.

GO DEEPERHow dive-bombing works →

· WHY IT MATTERED

The machine did the recovering

Pulling out of a 550 km/h vertical dive takes about 6 g, enough to grey a pilot out. So the Stuka did it itself: pressing the bomb release also triggered an automatic pull-out through the elevator trim. A contact altimeter lit a lamp at the preset release height — around 450 metres at the lowest — because below that there was no room left to recover.

· WHY IT MATTERED

Only as good as the air around it

At 400 km/h with a fixed undercarriage the Stuka was easy meat for a Spitfire or a Hurricane, and the Battle of Britain stopped its daylight career in the West within weeks. In the East, where the Luftwaffe kept air superiority longer, it went on — the Ju 87 G with two 37 mm cannon became the most effective tank-killing aircraft of the war in the right hands.

· THE ENGINE

An inverted V-12 that could fly upside down

The Jumo 211 hangs its twelve cylinders below the crankshaft — an inverted V — which gave the pilot a better view over the nose and made the guns and exhausts easier to package. More important for a dive-bomber, it was fuel-injected from the start: a carburettor engine coughs or cuts when the aircraft rolls inverted and the float chamber empties, and the Stuka rolled inverted into every attack. A two-speed supercharger gave it one gear for low altitude and one for high, the simplest way of matching an engine to the thin air it breathes higher up.

Junkers Jumo 211J · inverted V-12 · 35.0 L · direct injection · two-speed supercharger · 1,400 hp

GO DEEPEROpen the full demo →

· WEAPONS AND SPECIALITY

Bombs first; the guns were for the way home

The Stuka B carried one 250 kg bomb under the fuselage and four 50 kg bombs under the wings; the later D took a single 1,000 kg bomb. Its two forward machine guns fired about 0.5 kg of bullets a second between them — nothing by fighter standards — and the gunner behind had a twin gun for the fighters that would come. The famous siren, a small propeller-driven whistle on each leg, cost 20–25 km/h and crews often took it off. The Ju 87 G swapped the bombs for two 37 mm cannon with tungsten-cored shells, six rounds each side, and went hunting tanks.

· TRY IT

Its engine, live: 1,400 hp against thin air

The lab runs the Jumo 211J’s two-speed supercharger against the atmosphere: the power it makes falls as the air thins, jumps when the blower changes gear, and the aircraft’s speed follows. The Stuka rarely climbed high — the dive started from 4,000 m or so — which is why two gears were enough.

Readout

Power1,253 hp

Per engine1,253 hp

True airspeed410 km/h

Service ceiling7,300 m

A simplified model calibrated to the published rating and top speed — the shape of the curve is the point, not the third decimal.