Here’s yet another tiny masterpiece by master model maker Ron Colonna: a World War I-era Gnome rotary aircraft engine in 1:5 scale. And like all his creations, it runs like a fine watch.  

The rotary engine—sometimes called a radial rotary to distinguish it from modern rotaries like the Wankel—is among the strangest internal combustion engines ever conceived. At a superficial glance, a rotary looks much like a radial engine as commonly used in piston-era aircraft, with the same starfish-like cylinder layout, but there’s an important difference. In a rotary, the crankshaft is stationary and the cylinders and crankcase rotate, driving a propeller or output shaft. (There are a number of other peculiar features owing to this layout, but we’ll stop there for now.)

This may seem like an absurd way to configure an engine, but in the early days of piston engines, when fuels, lubricants, and materials were primitive compared to today, the rotary actually solved more problems than it created. Thanks in part to sure starting and a superior power-to-weight ratio, rotaries were extremely effective in World War I combat aircraft. Indeed, few were more effective than the nine-cylinder, 100-horsepower Gnome Monosoupape, which powered dozens of aircraft types in the Great War, including the Sopwith Camel of song and story.

Regular readers of Mac’s Motor City Garage are familiar with the exquisite work of master model maker Ron Colonna. Previously, we’ve featured his tiny Flathead V8, his four-cylinder Offy, and his Harley-Davidson Panhead. (Visit his website here.) This engine is an authentic 100 hp Gnome in 1:5 scale, which makes it roughly the same diameter as a man’s outstretched palm. And like all of Mr. Colonna’s creations, the miniature Gnome is beautifully constructed and runs like a fine watch. Watch this.