![cover image](https://wikiwandv2-19431.kxcdn.com/_next/image?url=https://upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Le_Rhone_9C.jpg/640px-Le_Rhone_9C.jpg&w=640&q=50)
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.
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Le_Rhone_9C.jpg/640px-Le_Rhone_9C.jpg)
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/2/21/FAAM_-_Le_Rh%C3%B4ne_9C_Sopwith_Pup_-_141213.jpg/640px-FAAM_-_Le_Rh%C3%B4ne_9C_Sopwith_Pup_-_141213.jpg)
Note the narrowness of the mounting pedestal to the fixed crankshaft (2013), and the size of the engine
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6f/MHV_Megola_01.jpg/640px-MHV_Megola_01.jpg)
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.