The Star Wars prequel movies featured various monowheel robots [3] andvehicles [4] amongst its various fantastical elements. After all, who in real life would be crazy enough to invent such impractical designs?
Why, the Nazis, of course!
The unique Kugelpanzer, or “ball tank”, was built in Germany and at some point shipped over to Japanese-occupied China. The sole prototype was then captured by the Russian Army in 1945 during its invasion of Manchuria. Plated in 5 millimeters of steel, the Kugelpanzer rolled on massive rollers 1.5 meters in diameter, manned by a single crew member sitting on motorcycle-style saddle. The driver could peer out into the battlefield through a narrow viewing slit and fire a single machine gun through a slot underneath the viewport.
A two-stroke 25 horsepower piston engine drove the bizarre conveyance, which was steered by a runner wheel on a tail extension which also must have contributed to stability. An article in Russian Popular Mechanicsestimates[8] the 1.8 ton Kugelpanzer wasn’t likely to win any races, rolling at a brisk jogging pace of 5 miles per hour.