Rotary engine
（重定向自Rotary piston engine）
![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.](/Images/godic/202502/08/Le_Rhone_9C2119.jpg")
![Animation of a seven-cylinder rotary engine with every-other-piston firing order.](/Images/godic/202502/08/Rotary_engine_-_animation_slower2119.gif")
2119.jpg")
![An 1897 Félix Millet motorcycle.](/Images/godic/202502/08/Felix_Millet2119.jpg")
The rotary engine was an early type of internal-combustion engine, usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary in operation, with the entire crankcase and its attached cylinders rotating around it as a unit. Its main application was in aviation, although it also saw use before its primary aviation role, in a few early motorcycles and automobiles.