This is the Megola motorcycle. It’s powered by a five-cylinder 650cc radial engine. In the front wheel.
The Megola was built in Germany in the ’20s. It used a radial-rotary engine similar to those found in WWI biplanes. The engine works like a radial, but the crankshaft remains stationary while the engine spins around it. In biplanes, the engine was attached to the propeller. In the Megola, it’s attached to the font wheel. This mind-boggling configuration required no transmission and could propel the bike to a psychotic 52 mph top speed. Hit the jump for a video of the bike in action.
And here’s a video of a Gnome rotary-radial biplane engine running on a stand.
To get a real sense of how this thing works, check out the animation here.