Did you know Nazi Germany tried to build a coal-powered plane?

A (non-working) replica of the Lippisch P.13a
(Photo: Zackcbowen / Wikipedia)

The weird Wunderwaffen (“wonder-weapons”) were a staple of German weapons design during World War II, but it would be hard to find something stranger than this: a jet plane running on coal, taking down Allied bombers by ramming into them. And yet, the Lippisch P.13a would have been exactly that, had it ever been built (and had it worked).

Designer Alexander Lippisch originally proposed a flying wing with the pilot seated inside the oversized tail fin as a cheap and disposable weapon against the vast Allied bomber formations. The unarmed but reinforced plane would have simply rammed its targets, after which the pilot would have bailed out (though landing skids were added in a later version).

A Dornier Do 217 bomber carrying a Lorin ramjet engine, similar to the one intended for the Lippisch P.13a, for testing
(Photo: unknown photographer)

Germany was suffering from a crippling lack of fuel in the last years of the war, so Lippisch suggested using coal granules as fuel in a ramjet engine. The plane would have first needed to reach a certain speed (by being towed or catapulted) for the engine to kick in: air then would have been compressed and conducted to a combustion chamber through an opening in the plane’s nose. The burning coal, held in a rotating metal cage, would have heated up the cold compressed air, causing it to rapidly expand and blow out at the back, pushing the plane forward.

The glider used to test the plane’s shape
(Photo: Akaflieg München e.V.)

The idea sounds crazy, but would it have worked? We’ll never know for sure, as the war ended before a prototype could have been built. Ramjets do work, and some of them use solid fuel. A life-sized glider used as a model for the plane’s fuselage was largely built during the war, completed by the Allies and tested in a wind tunnel – the original design had some problems, but nothing that couldn’t be fixed. It’s extremely unlikely that the plane, built with mid-40s technology in war-torn Germany would have worked nearly as well as intended, but fundamental principles behind the bizarre idea were actually rather solid.