Editing Aircraft engine (section)

====Wankel engine====
{{main|Wankel engine}}
[[File:WankelPP.jpg|thumb|upright|right|Powerplant from a [[Schleicher ASH 26]]e self-launching [[motor glider]], removed from the glider and mounted on a test stand for maintenance at the [[Alexander Schleicher GmbH & Co]] in [[:de:Poppenhausen (Wasserkuppe)|Poppenhausen]], [[Germany]]. Counter-clockwise from top left: propeller hub, mast with belt guide, radiator, Wankel engine, muffler shroud.]]

The [[Wankel engine|Wankel]] is a type of rotary engine. The [[Wankel engine]] is about one half the weight and size of a traditional [[four-stroke cycle]] [[piston engine]] of equal power output, and much lower in complexity. In an aircraft application, the power-to-weight ratio is very important, making the Wankel engine a good choice. Because the engine is typically constructed with an aluminium housing and a steel rotor, and aluminium expands more than steel when heated, a Wankel engine does not seize when overheated, unlike a piston engine. This is an important safety factor for aeronautical use. Considerable development of these designs started after [[World War II]], but at the time the aircraft industry favored the use of [[turbine]] engines. It was believed that [[turbojet]] or [[turboprop]] engines could power all aircraft, from the largest to smallest designs. The Wankel engine did not find many applications in aircraft, but was used by [[Mazda]] in a popular line of [[sports cars]]. The French company [[Citroën]] had developed Wankel powered {{Interlanguage link|Citroën RE-2|fr|3=Citroën RE-2|lt=RE-2}} [[helicopter]] in 1970's.<ref name="PBoulay">{{Cite book|language=fr|first=Pierre|last=Boulay|title=Les hélicoptères français|editor=Guides Larivière|year=1998|publisher=Larivière (Editions) |isbn=978-2-907051-17-0}}</ref>

In modern times the Wankel engine has been used in [[motor glider]]s where the compactness, light weight, and smoothness are crucially important.<ref>{{cite web
|url = http://www.alexander-schleicher.de/englisch/produkte/ash26/e_ash26_main.htm
| publisher = Alexander Schleicher | title = ASH 26 E Information
|access-date = 2006-11-24 | location = DE
|archive-url = https://web.archive.org/web/20061008125929/http://www.alexander-schleicher.de/englisch/produkte/ash26/e_ash26_main.htm |archive-date = 2006-10-08}}</ref>