Editing Wankel engine (section)

==Concept==
{{Multiple image
| direction = vertical
| width = 250
| header = Rotary engine types
| image1 = DrehkolbenmotorDKM54.JPG
| caption1 = '''Figure 2.'''<br/>The first DKM Wankel engine designed by [[Felix Wankel]], the DKM 54 (''Drehkolbenmotor''), at the Deutsches Museum in [[Bonn]]
| image2 = Wankel-1.jpg
| caption2 = '''Figure 3.'''<br/>A Wankel engine with its rotor and geared output shaft
| image3 = Wankelmotor-KKM57P.jpg
| caption3 = '''Figure 5.'''<br/>The first KKM Wankel Engine based on a design by Hanns-Dieter Paschke, the [[NSU Motorenwerke|NSU]] KKM 57P (''Kreiskolbenmotor''), at Autovision und Forum
| image4 = NSU-Spider-Motorraum.jpg
| caption4 = '''Figure 6.'''<br/>First production Wankel engine; installed in an [[NSU Spider]]
}}
The Wankel engine is a type of rotary piston engine and exists in two primary forms, the '''''Drehkolbenmotor''''' (DKM, "rotary piston engine"), designed by Felix Wankel (see Figure 2.) and the '''''Kreiskolbenmotor''''' (KKM, "circuitous piston engine"), designed by Hanns-Dieter Paschke<ref name="Norbye 1971 p. 357">{{cite book |last1=Norbye |first1=J.P. |title=The Wankel Engine: Design, Development, Applications |publisher=Chilton |year=1971 |isbn=978-0-8019-5591-4 |page=357}}</ref> (see Figure 3.), of which only the latter has left the prototype stage. Thus, all production Wankel engines are of the KKM type.

* In a '''DKM engine''', there are two rotors: the inner, trochoid-shaped rotor, and the outer rotor, which has an outer circular shape, and an inner figure eight shape. The center shaft is stationary, and torque is taken off the outer rotor, which is geared to the inner rotor.<ref name="Hege 2015 p. 56">{{cite book |last1=Hege |first1=J.B. |title=The Wankel Rotary Engine: A History |publisher=McFarland |series=EBL-Schweitzer |year=2015 |isbn=978-0-7864-8658-8 |page=56}}</ref>
* In a '''KKM engine''', the outer rotor is part of the stationary housing (thus not a moving part). The inner shaft is a moving part with an eccentric lobe for the inner rotor to spin around. The rotor spins around its center and around the axis of the eccentric shaft in a hula hoop fashion, resulting in the rotor making one complete revolution for every three revolutions of the eccentric shaft. In the KKM engine, torque is taken off the eccentric shaft,<ref name="Hege 2015 p. 53">{{cite book |last1=Hege |first1=J.B. |title=The Wankel Rotary Engine: A History |publisher=McFarland |series=EBL-Schweitzer |year=2015 |isbn=978-0-7864-8658-8 |page=53}}</ref> making it a much simpler design to be adopted to conventional powertrains.<ref name="Hege 2015 p. 54">{{cite book |last1=Hege |first1=J.B. |title=The Wankel Rotary Engine: A History |publisher=McFarland |series=EBL-Schweitzer |year=2015 |isbn=978-0-7864-8658-8 |page=54}}</ref>