Editing Wankel engine (section)

==Non-road vehicle applications==

===Aircraft===
{{Multiple image
| direction = vertical
| width = 250
| header = Aircraft rotary engines
| image1 = Wankel RC2-60 Rotary Engine.jpg
| caption1 = '''Figure 28.'''<br/>Wankel RC2-60 Aeronautical Rotary Engine
| image2 = ARV Midwest.pdf|thumb|right
| caption2 = '''Figure 29.'''<br/>ARV Super2 with the British [[MidWest AE series|MidWest AE110]] twin-rotor Wankel engine
| image3 = Diamond-Katana-DA20-Wankel.jpg
| caption3 = '''Figure 30.'''<br/>[[Diamond DA20]] with a Diamond Engines Wankel
| image4 = Cypher-UAV.JPG
| caption4 = '''Figure 31.'''<br/>[[Sikorsky Cypher]] Unmanned aerial vehicle (UAV) powered with a UEL AR801 Wankel engine
| image5 = Citroën RE-2.jpg
| caption5 = '''Figure 32.'''<br/>Citroën RE-2 helicopter in 1975
}}

Rotary engines are well suited for light aircraft, being light, compact, almost vibrationless, and with a high [[power-to-weight ratio]]. Further aviation benefits include:

# The engine is not susceptible to ''shock-cooling'' during descent;
# The engine does not require an enriched mixture for cooling at high power;
# Having no reciprocating parts, less vulnerability to damage occurs when the engine revolves at a higher rate than the designed maximum.

Unlike cars and motorcycles, a rotary aero-engine can be sufficiently warm before full power is applied because of the time taken for pre-flight checks. Also, the journey to the runway has minimum cooling, which further permits the engine to reach the operating temperature for full power on take-off.<ref name="H8TbB">MidWest Engines Ltd AE1100R Rotary Engine Manual</ref> A Wankel aero-engine spends most of its operational time at high power outputs, with little idling.

Since rotary engines operate at a relatively high [[rotational speed]], at 6,000{{nbsp}}rpm of the output shaft, the rotor spins only at about one-third of that speed. With relatively low torque, propeller-driven aircraft must use a [[propeller Speed Reduction Unit|propeller speed reduction unit]] to maintain propellers within the designed speed range. Experimental aircraft with Wankel engines use propeller speed reduction units; for example, the [[MidWest AE series|MidWest]] twin-rotor engine has a 2.95:1 reduction gearbox.

The first rotary engine aircraft was in the late-1960s in the experimental [[Lockheed Corporation|Lockheed]] [[Q-Star]] civilian version of the [[United States Army]]'s reconnaissance [[Lockheed YO-3 Quiet Star|QT-2]], essentially a powered [[Schweizer Aircraft Corporation|Schweizer]] [[sailplane]].<ref>{{cite web |title=Lockheed QT-2 / Lockheed Q-Star |url= http://all-aero.com/index.php/contactus/53-planes-l-m-n-o/6207-lockheed-qt-2--q-star |website=all-aero.com |access-date=19 January 2023}}</ref> The plane was powered by a {{convert|185|hp|abbr=on}} [[Curtiss-Wright]] RC2-60 Wankel rotary engine.<ref name="airandspace.si.edu">{{cite web |title=Wright Aeronautical (Wankel) RC2-60 Rotary Engine |url= https://airandspace.si.edu/collection-objects/wright-aeronautical-wankel-rc2-60-rotary-engine/nasm_A19870228000 |work=National Air and Space Museum |access-date=19 January 2023}}</ref> The same engine model was also used in a Cessna Cardinal and a helicopter, as well as other airplanes.<ref name="PS-April-1966"/><ref name="kza2k">{{Citation |title=A Survey of Curtiss-Wright's 1958–1971 Rotating Combustion Engine Technological Developments |series=SAE |format=PDF |url= http://papers.sae.org/720468 |number=720468 |first1=Charles |last1=Jones |place=Detroit, IL, USA |date=May 1972| volume=1 |doi=10.4271/720468 |url-access=subscription }}</ref><ref name="PTyY3">{{cite web |url= http://www.der-wankelmotor.de/Motoren/Curtiss_Wright/curtiss_wright.html |title=Curtiss & Wright |publisher= Der Wankelmotor |location=DE |access-date=2009-07-03}}</ref> The French company [[Citroën]] developed a rotary-powered {{Interlanguage link|Citroën RE-2|fr|3=Citroën RE-2|lt=RE-2}} [[helicopter]] in the 1970s.<ref name="PBoulay">{{cite book|language=fr|first1=Pierre|last1=Boulay|title=Les hélicoptères français|editor=Guides Larivière|year=1998|publisher=Larivière (Editions) |isbn=2-907051-17-2}}</ref> In Germany in the mid-1970s, a pusher ducted fan airplane powered by a modified NSU multi-rotor rotary engine was developed in both civilian and military versions, Fanliner and Fantrainer.<ref name="Popular Science p. 88">{{cite magazine |first1=Ben |last1=Kocivar |title=Wankel Fanliner |magazine=Popular Science |issn=0161-7370 |date=March 1977 |page=88}}</ref>

At roughly the same time as the first experiments with full-scale aircraft powered with rotary engines, [[Model engine|model aircraft]]-sized versions were pioneered by a combination of the well-known Japanese [[O.S. Engines]] firm and the then-extant German [[Graupner (company)|Graupner]] aeromodelling products firm, under license from NSU. The Graupner model Wankel engine has a chamber volume V<sub>k</sub> of 4.9&nbsp;cm<sup>3</sup>, and produces 460&nbsp;W at 16,000&nbsp;rpm<sup>&minus;1</sup>; its mass is 370&nbsp;g. It was produced by O.S. engines of Japan.<ref name="Bensinger 1973 p. 142">{{cite book |last1=Bensinger |first1=Wolf-Dieter |title=Rotationskolben-Verbrennungsmotoren |place=Berlin, Heidelberg, New York |date=1973 |isbn=978-3-540-05886-1 |oclc=251737493 |language=de |page=142}}</ref>

Rotary engines have been fitted in homebuilt experimental aircraft, such as the [[ARV Super2]], a couple of which were powered by the British [[MidWest AE series|MidWest]] aero-engine. Most are Mazda 12A and 13B automobile engines, converted for aviation use. This is a very cost-effective alternative to certified aircraft engines, providing engines ranging from 100 to {{convert|300|hp}} at a fraction of the cost of traditional piston engines. These conversions were initially in the early 1970s. Peter Garrison, a contributing editor for ''Flying'' magazine, wrote "in my opinion&nbsp;… the most promising engine for aviation use is the Mazda rotary."<ref name="kqNVP">"Revisiting Rotaries", Peter Garrison, ''Flying'', '''130''', #6 (June 2003), pp. 90 ff.</ref>

The [[glider (sailplane)|sailplane]] manufacturer [[Alexander Schleicher GmbH & Co|Schleicher]] uses an [[Austro Engine AE50R]] engine<ref name="Austro Engines AR50">{{cite web|url=https://www.austroengine.at/produkte |title=Produkte Kreiskolbenmotoren}}</ref><ref name="Austro Engines AR50 and IAE50R-AA">{{cite web|url=https://www.alexander-schleicher.de/en/austro-engine-verlaengert-wartungsintervalle-fuer-wankelmotoren/ |title =Austro Engine extends service intervals of rotary engines|date =26 November 2019}}</ref> in its self-launching models [[Schleicher ASK 21|ASK-21 Mi]], [[Schleicher ASH 26|ASH-26E]],<ref name="ASH26">{{cite web|url=http://www.postfrontal.com/PDF/prove_alianti/ASH26.pdf |title=A Flight Test Evaluation of the ASH-26E Self Launching 18-Meter Sailplane |access-date=31 August 2011 |last1=Johnson |first1=Richard |date=September 1995}}</ref> [[Schleicher ASH 25|ASH-25 M/Mi]], [[Schleicher ASH 30|ASH-30 Mi]], [[Schleicher ASH 31|ASH-31 Mi]], [[Schleicher ASW 22|ASW-22 BLE]], and [[Schleicher ASG 32|ASG-32 Mi]].

In 2013, [[e-Go]] airplanes, based in [[Cambridge]], United Kingdom, announced that a rotary engine from Rotron Power will power its new single-seater canard aircraft.<ref name="q17tm">{{cite web|url= http://www.e-goaeroplanes.com/the-aeroplane/introduction/ |title=GioCAS 2017 – Aeronautical Consultancy |website=e-goaeroplanes.com}}</ref>

The DA36 E-Star, an aircraft designed by [[Siemens]], [[Diamond Aircraft Industries|Diamond Aircraft]] and [[EADS]], employs a [[series hybrid]] powertrain with the propeller being turned by a Siemens {{convert|70|kW|abbr=on}} electric motor. The aim is to reduce fuel consumption and emissions by up to 25%. An onboard {{convert|40|hp|abbr=on}} [[Austro Engine]] engine and generator provide the electricity. A propeller speed reduction unit is eliminated. The electric motor uses electricity stored in batteries, with the generator engine off, to take off and climb reducing sound emissions. The series-hybrid powertrain using the Wankel engine reduces the plane's weight by 100&nbsp;kg relative to its predecessor. The DA36 E-Star first flew in June 2013, making this the first-ever flight of a series-hybrid powertrain. Diamond Aircraft claims that rotary engine technology is scalable to a 100-seat aircraft.<ref name="RcilK">{{cite web |url= http://green.autoblog.com/2011/07/03/siemens-diamond-aircraft-eads-unveil-worlds-first-serial-hybr/ |title=Siemens, Diamond Aircraft, EADS unveil world's first serial hybrid aircraft |website=green.autoblog.com |date=2011-07-03 |access-date=2011-07-03 |archive-date=2011-07-07 |archive-url= https://web.archive.org/web/20110707025157/http://green.autoblog.com/2011/07/03/siemens-diamond-aircraft-eads-unveil-worlds-first-serial-hybr/ |url-status=dead}}</ref><ref name="SmURs">{{cite web|url= http://www.greencarcongress.com/2013/06/eads-21030618.html |title=EADS and Siemens enter long-term research partnership for electric aviation propulsion; MoU with Diamond Aircraft |website=greencarcongress.com |date=2013-06-18 |access-date=2014-02-01}}</ref>

===Trains===
Since 2015, a total of 60 trains in Germany have been equipped with Wankel-engined auxiliary power systems that burn diesel fuel. The locomotives use the WST KKM 351 Wankel diesel fuel engine.<ref name="auto"/>

===Other uses===
[[File:UAV-741-F.jpg|thumb|'''Figure 33.'''<br/>UEL UAV-741 Wankel engine for [[AAI RQ-7 Shadow]] [[UAV]]]]

The Wankel engine is well-suited for devices in which a human operator is close to the engine, e.g., hand-held devices such as chainsaws.<ref name="Ansdale Keller 1971 p. 214">{{cite book |last1=Ansdale |first1=R.F. |last2=Keller |first2=H. |title=Der Wankelmotor: Konstruktion und Wirkungsweise |place=Stuttgart| publisher=Motorbuch-Verlag |year=1971 |language=de |page=214}}</ref> The excellent starting behavior and low mass make the Wankel engine also a good powerplant for portable fire pumps and portable power generators.<ref name="Ansdale Keller 1971 p. 215">{{cite book |last1=Ansdale |first1=R.F. |last2=Keller |first2=H. |title=Der Wankelmotor: Konstruktion und Wirkungsweise |place=Stuttgart| publisher=Motorbuch-Verlag |year=1971 |language=de |page=215}}</ref>

Small Wankel engines are being found in applications such as [[kart racing|go-karts]], [[personal watercraft]], and [[auxiliary power unit]]s for aircraft.<ref name="o4ITr">{{cite web|url= http://www.der-wankelmotor.de/Motoren/UAV/Pats/pats.html |title=Pats APU |publisher=Der Wankelmotor |location=DE |access-date= 2009-07-03}}</ref> [[Kawasaki Heavy Industries|Kawasaki]] patented mixture-cooled rotary engine (US patent 3991722). Japanese diesel engine manufacturer [[Yanmar]] and [[Dolmar|Dolmar-Sachs]] of Germany had a rotary-engined chain saw (SAE paper 760642) and outboard boat engines, and the French Outils Wolf, made a lawnmower (Rotondor) powered by a Wankel rotary engine. The rotor was in a horizontal position to save on production costs, and there were no seals on the downside.

The simplicity of the rotary engine makes it well-suited for mini, micro, and micro-mini engine designs. The [[Microelectromechanical systems]] (MEMS) Rotary Engine Lab at the [[University of California, Berkeley]], formerly researched developing rotary engines down to 1&nbsp;mm in diameter, with displacements less than 0.1&nbsp;cc. Materials include silicon, and motive power includes compressed air. The goal of such research was to eventually develop an internal combustion engine with the ability to deliver 100 milliwatts of electrical power, with the engine serving as the rotor of the [[electric generator]], with [[magnet]]s built into the engine rotor.<ref name="zRdO7">{{cite journal |title=MEMS Rotary Engine Power System |journal=IEEJ Transactions on Sensors and Micromachines |volume=123 |issue=9 |pages=326 |publisher=University of California |location=Berkeley, California |date=2004-01-14 |bibcode=2003IJTSM.123..326F |last1=Fernandez-Pello |first1=A. Carlos |last2=Pisano |first2=Albert P. |last3=Fu |first3=Kelvin |last4=Walther |first4=David C. |last5=Knobloch |first5=Aaron |last6=Martinez |first6=Fabian |last7=Senesky |first7=Matt |last8=Stoldt |first8=Conrad |last9=Maboudian |first9=Roya |last10=Sanders |first10=Seth |last11=Liepmann |first11=Dorian |doi=10.1541/ieejsmas.123.326 |doi-access=free}}</ref><ref name="ZZSJW">{{cite web|url= http://www.me.berkeley.edu/cpl/media/memsff01.pdf |title=34474_2 |access-date=2010-12-20 |url-status=dead |archive-url= https://web.archive.org/web/20100710020103/http://www.me.berkeley.edu/cpl/media/memsff01.pdf |archive-date=July 10, 2010}}</ref> Development of the miniature rotary engine stopped at UC Berkeley at the end of the DARPA contract.

In 1976, ''Road & Track'' reported that [[Ingersoll-Rand]] would develop a Wankel engine with a chamber volume V<sub>k</sub> of {{cvt|25|dm3|in3|-2|order=flip}} with a rated power of {{cvt|500|hp|kW|0}} per rotor.<ref name="Road & Track 1976 p. 89">{{cite book |title=Road & Track |publisher=Bond Publishing |issue=Bd. 28 |year=1976 |page=89}}</ref> Eventually, 13 units of the proposed engine were built, albeit with a larger displacement, and covered over 90,000 operating hours combined. The engine was made with a chamber volume V<sub>k</sub> of {{cvt|2500|in3|dm3|0}}, and a power output of {{cvt|550|hp|kW|0}} per rotor. Both single, and twin-rotor engines were made (producing {{cvt|550|hp|kW|0}} or {{cvt|1100|hp|kW|0}} respectively). The engines ran on natural gas and had a relatively low engine speed due to its application.<ref name="The Rotary Combustion Engine: A Candidate for General Aviation 1978 p. 127">{{cite book |title=The Rotary Combustion Engine: A Candidate for General Aviation |editor=((National Aeronautics and Space Administration)) |series=NASA conference publication |year=1978 |page=127}}</ref>

[[Deere & Company]] acquired the Curtiss-Wright rotary division in February 1984, making large multi-fuel prototypes, some with an 11-liter rotor for large vehicles.<ref name=silvestri/><ref name="DgihD">{{Citation |title=Stratified Charge Rotary Engine Developments at JDTI (John Deere Technologies International) from 1984 to 1991 |first1=Charles |last1=Jones |year=1992}}</ref><ref>{{cite web |last1=Proft |first1=Bill |title=The John Deere Rotary Engine |url= https://greenmagazine.com/the-john-deere-rotary-engine/ |website=greenmagazine.com |date=9 October 2018}}</ref> The developers attempted to use a stratified charge concept.<ref name=silvestri>{{cite web |first1=William B. |last1=Silvestri |first2=Edward S. |last2=Wright |title=John Deere Score Engines in Marine Applications |url= https://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1986/79290/V002T03A005/2396441/v002t03a005-86-gt-256.pdf |publisher=American Society of Mechanical Engineers |date=1986 }}</ref> The technology was transferred to RPI in 1991.<ref>{{cite news |title=Deere Pulls Out of the Rotary Engine Race |url= https://www.chicagotribune.com/news/ct-xpm-1991-04-10-9102020081-story.html |newspaper=Chicago Tribune |date=10 April 1991 }}</ref><ref>{{cite web |last1=Gilboy |first1=James |title=The 11.6-Liter, Big-Block Diesel Rotary Was Just Too Good for This World |url= https://www.thedrive.com/news/36426/the-11-6-liter-big-block-diesel-rotary-was-just-too-good-for-this-world |website=thedrive.com |archive-url= https://web.archive.org/web/20210803024956/https://www.thedrive.com/news/36426/the-11-6-liter-big-block-diesel-rotary-was-just-too-good-for-this-world |archive-date=3 August 2021 |date=15 September 2020 |url-status=live}}</ref>

[[Yanmar]] of Japan produced small, charge-cooled rotary engines for chainsaws and outboard engines.<ref name="JhAV3">{{cite web|url= http://www.der-wankelmotor.de/Motoren/Yanmar-Diesel/yanmar-diesel.html |title=Yanmar Diesel |publisher=Der Wankelmotor |location=DE |access-date=2010-12-20}}</ref> One of its products is the LDR (rotor recess in the leading edge of the combustion chamber) engine, which has better exhaust emissions profiles, and reed-valve controlled intake ports, which improve part-load and low rpm performance.<ref name="HMj5q">{{Citation |first1=Kojiro |last1=Yamaoka |first2=Hiroshi |last2=Tado |publisher=SAE |title=720466 |year=1972}}</ref>

In 1971 and 1972, [[Arctic Cat]] produced snowmobiles powered by Sachs KM 914 303-cc and KC-24 294-cc Wankel engines made in Germany.

In the early 1970s, [[Outboard Marine Corporation]] sold snowmobiles under the Johnson and other brands, which were powered by {{convert|35|or|45|hp|abbr=on}} OMC engines.

Aixro of Germany produces and sells a go-kart engine with a 294-cc-chamber charge-cooled rotor and liquid-cooled housings. Other makers include Wankel AG, Cubewano, Rotron, and Precision Technology.

===Non-internal combustion===
[[File:Wankel-Airco.jpg|thumb|'''Figure 34.'''<br/>Ogura Wankel Air conditioning system compressor]]

In addition to applications as an internal combustion engine, the basic Wankel design has also been used for [[gas compressor]]s, and [[supercharger]]s for internal combustion engines, but in these cases, although the design still offers advantages in reliability, the primary advantages of the Wankel in size and weight over the four-stroke internal combustion engine are irrelevant. In a design using a Wankel supercharger on a Wankel engine, the supercharger is twice the size of the engine.

The Wankel design is used in the [[seat belt]] pre-tensioner system<ref name="DT41N">{{cite web|url= https://patents.google.com/patent/US5485970 |title=TRW Wankel pre-tensioner system |access-date=2009-07-03}}</ref> in some [[Mercedes-Benz]]<ref name="HcEdw">{{cite web |url= http://www.mercedestechstore.com/pdfs/507%20Systems%20I/507%20HO%20SRS%20(GC%20ICC)%2010-30-02.pdf |title=Occupant Safety Systems |website=mercedestechstore.com |pages=11–12 |access-date=2007-12-31 |url-status=dead |archive-url= https://web.archive.org/web/20080228083751/http://www.mercedestechstore.com/pdfs/507%20Systems%20I/507%20HO%20SRS%20%28GC%20ICC%29%2010-30-02.pdf |archive-date=2008-02-28}}</ref> and [[Volkswagen]]<ref name="nVs9X">{{cite web |url= http://www.trw-eos.com/enG/about_us/trw_original_equipment.aspx |title=Original Equipment |website=trw-eos.com |access-date=2009-02-12 |archive-url= https://web.archive.org/web/20080311074151/http://www.trw-eos.com/enG/about_us/trw_original_equipment.aspx |archive-date=March 11, 2008}}</ref> cars. When the [[deceleration]] [[sensor]]s detect a potential crash, small explosive cartridges are triggered electrically, and the resulting pressurized gas feeds into tiny Wankel engines, which rotate to take up the slack in the seat belt systems, anchoring the driver and passengers firmly in the seat before a collision.<ref name="5FrID">{{cite web |url= https://patents.google.com/patent/US5485970 |title=Seat belt pretensioner |first1=Charles E. Jr. |last1=Steffens |access-date=2007-04-11}}</ref>