Editing Rotary engine (section)

{{Short description|Internal combustion engine with cylinders rotating around a stationary crankshaft}}
{{About|an obsolete type of piston engine with a rotating crankcase|the pistonless Wankel engine|Wankel engine|other engines described as "rotary"}}
[[File:Le Rhone 9C.jpg|thumb|upright=1.14|An {{convert|80|hp}} 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]].]]
[[File:FAAM - Le Rhône 9C Sopwith Pup - 141213.jpg|thumb|right|This '''Le Rhône 9C''' installed on a [[Sopwith Pup]] fighter aircraft at the [[Fleet Air Arm Museum]].<br>Note the narrowness of the mounting pedestal to the fixed crankshaft (2013), and the size of the engine]]
[[File:MHV Megola 01.jpg|thumb|[[Megola]] motorcycle with rotary engine mounted in the front wheel]]

The '''rotary engine''' is an early type of [[internal combustion engine]], usually designed with an odd number of cylinders per row in a [[radial engine|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 [[motorcycle]]s and [[automobile]]s.

This type of engine was widely used as an alternative to conventional [[Inline engine (aviation)|inline engines]] ([[Straight engine|straight]] or [[V engine|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".<ref name="nahum40">{{cite book| last = Nahum| first = Andrew| title = The Rotary Aero Engine| year = 1999| publisher = NMSI Trading Ltd| isbn = 1-900747-12-X| pages = 40 }}</ref>

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