>When moving circle is outside, its called Epitrochoid >https://en.wikipedia.org/wiki/Epitrochoid https://en.wikipedia.org/wiki/Epitrochoid The combustion cha

>When moving circle is outside, its called Epitrochoid >https://en.wikipedia.org/wiki/Epitrochoid https://en.wikipedia.org/wiki/Epitrochoid The combustion chamber of the Wankel engine is an epitrochoid. (From the above Wikipedia link.) I had read up about Wankel (and also the more conventional internal combustion) engines as a kid. Thought the Wankel engine idea was cool. It has both pros and cons. https://en.wikipedia.org/wiki/Wankel_engine https://en.wikipedia.org/wiki/Wankel_engine