Germany went into the Second World War without a modern four-engine heavy bomber, and it spent much of the war failing to build one. The aircraft meant to fix that — the Heinkel He 177 Greif — had four engines but only two propellers, a quirk that made it burst into flames so often the crews called it the Reichsfeuerzeug: the Reich’s cigarette lighter.

It is one of the great self-inflicted wounds of wartime aviation — a capable airframe ruined by a single stubborn requirement.

Four engines, two propellers

The engineering at the heart of the He 177 is the key to the whole story. To keep drag low, Heinkel did not hang four separate engines under the wings. Instead it bolted pairs of Daimler-Benz inverted-V12 engines together, side by side, each pair geared to a single propeller. So the He 177 had four engines but only two nacelles and two props — it looked like a twin, and flew like a very troubled one.

Cramming two hot engines into one tight nacelle, with oil and fuel lines running past red-hot exhaust manifolds, produced exactly what you would expect. Leaks dripped onto hot metal and caught fire. Six of the first eight prototypes were lost, most of them to engine fires.

The reason for this dangerous arrangement was a requirement that made no sense for a heavy bomber: the Luftwaffe insisted the He 177 be able to dive-bomb. Coupling the engines was meant to keep the airframe clean and strong enough for diving. Ernst Udet championed the idea; Heinkel’s pleas to simply use four separate engines were refused.

Even Hitler and Göring gave up on it

The fury inside the German high command was extraordinary. In August 1942, Hermann Göring vented about the coupled engines in language that needs no translation.

Hitler himself dismissed the entire programme, reaching back to the First World War for a precedent.

The dive-bombing requirement was finally dropped in September 1942, and later aircraft switched to the more powerful DB 610 coupled engines with redesigned nacelles, which reduced — but never entirely cured — the fires.

Too little, far too late

Between roughly 1,100 and 1,170 were built, but the Greif never became the war-winning weapon its potential suggested. It flew raids on England where crews aborted with overheating engines, hauled supplies on the Eastern Front, and was thrown into the doomed effort to keep Stalingrad alive. A version with four separate engines, the He 177B, finally flew in 1944 — long after German bomber production had been all but abandoned.

The tragedy of the He 177 is that the airframe was sound. Freed of the dive-bomber requirement and given four honest engines from the start, it might have been Germany’s Lancaster. Instead it became a cautionary tale about what happens when a single specification is allowed to set a whole aircraft on fire.

Sources: Defense Media Network; Wikipedia; Bundesarchiv.