Editing Pistonless rotary engine

{{short description|Internal combustion engine}}
{{About|pistonless design|other uses of this term|rotary engine (disambiguation)|the early piston design|rotary engine}}
{{more citations needed|date=April 2016}}
[[File:Rotary Engine Photo Sequence 01.gif|thumb|[[Libralato engine]] ]]

A '''pistonless rotary engine''' is an [[internal combustion engine]] that does not use [[piston]]s in the way a [[reciprocating engine]] does. Designs vary widely but typically involve one or more [[wikt:rotor|rotor]]s, sometimes called '''rotary pistons''', as described in QT-Wankel: Two Concepts 100 Years Apart.<ref>{{cite journal |author=Gilles Saint-Hilaire |author2=Roxan Saint-Hilaire |author3=Ylian Saint-Hilaire |author4=Françoise Saint-Hilaire |journal=International Journal of Science and Research |volume=14 |issue=2 |date=February 2025 |url=https://www.ijsr.net/archive/v14i2/SR25210033851.pdf |title=Comparative Analysis of Quasiturbine and Wankel Rotary Engine: Two Concepts 100 Years Apart |pages=723–743 |doi=10.21275/SR25210033851}}</ref> Although many different designs have been constructed, only the [[Wankel engine]] has achieved widespread adoption.

The term '''rotary combustion engine''' has been used as a name for these engines{{Citation needed|date=July 2010}} to distinguish them from early (generally up to the early 1920s) [[aircraft engine]]s and [[motorcycle engine]]s also known as ''[[rotary engine]]s''. However, both continue to be called ''rotary engines'' and only the context determines which type is meant, whereas the "pistonless" prefix is less ambiguous.

==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]]

==See also==
* [[Range extender (vehicle)]]

==References==
{{reflist}}

== Further reading ==
* Jan P. Norbye: 'Rivals to the Wankel: A Roundup of Rotary Engines', Popular Science, Jan 1967, pp 80–85. [https://books.google.com/books?id=CSEDAAAAMBAJ]
* [https://www.macsmotorcitygarage.com/ramblers-forgotten-1964-rotary-engine/?fbclid=IwAR2iWLJPySVAqwdxyR9EqQPKJxcsqfRTj7dNfLpcTo7aO2AvDdPR6xMqO-U Article referencing the October 1964 issue of Mechanix Illustrated and the AMC/Rambler rotary]
{{Heat engines}}

{{Authority control}}

[[Category:Pistonless rotary engine| ]]
[[Category:Proposed engines]]
[[Category:Engine technology]]

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