Rotary engine

Internal combustion engine with cylinders rotating around a stationary crankshaft / From Wikipedia, the free encyclopedia

The rotary engine is an early type of internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration. The engine's crankshaft remained stationary in operation, while the entire crankcase and its attached cylinders rotated around it as a unit. Its main application was in aviation, although it also saw use in a few early motorcycles and automobiles.

An 80 horsepower (60 kW) rated Le Rhône 9C, a typical rotary engine of WWI. The copper pipes carry the fuel-air mixture from the crankcase to the cylinder heads acting collectively as an intake manifold.
This Le Rhône 9C installed on a Sopwith Pup fighter aircraft at the Fleet Air Arm Museum.
Note the narrowness of the mounting pedestal to the fixed crankshaft (2013), and the size of the engine
Megola motorcycle with rotary engine mounted in the front wheel

This type of engine was widely used as an alternative to conventional inline engines (straight or V) during World War I and the years immediately preceding that conflict. It has been described as "a very efficient solution to the problems of power output, weight, and reliability".[1]

By the early 1920s, the inherent limitations of this type of engine had rendered it obsolete.