Editing Pistonless rotary engine (section)

==Pistonless rotary engines==
A pistonless rotary engine replaces the linear reciprocating motion of a piston with more complex compression/expansion motions with the objective of improving some aspect of the engine's operation, such as: higher efficiency [[Thermodynamic cycle|thermodynamic cycles]], lower [[Stress (mechanics)|mechanical stress]], lower vibration, higher [[Compression ratio|compression]], or less mechanical complexity. {{As of|2006}} the Wankel engine is the only successful pistonless rotary engine, but many similar concepts have been proposed and are under various stages of development. Examples of rotary engines include:

'''Production stage'''
*[[Wankel engine]]
*[[LiquidPiston]] engine
* Beauchamp Tower's nineteenth century [http://www.douglas-self.com/MUSEUM/POWER/tower/tower.htm spherical steam engine] (in actual use as a steam engine, but theoretically adaptable to use internal combustion)

'''Development stage'''
*[[Angelo Di Pietro (inventor)#Di Pietro Motor|Engineair engine]]
*[[Hamilton Walker (New Zealand)|Hamilton Walker]] engines
*Libralato rotary [[Atkinson cycle]] engine
*[[Nutating disc engine]]
*[[RKM engine]], {{langx|de|RotationsKolbenMaschine}}
*[[Sarich orbital engine]]
*[[Swing-piston engine]], Trochilic<!-- see talk page -->
*[[Wave disk engine]]

'''Conceptual stage'''
*[[Gerotor]] engine
*Internally Radiating Impulse Structure: [[IRIS engine]]