Editing Wankel engine (section)

===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>