Two-rotor Wankel Engine

The Wankel rotary engine is a type of internal combustion engine that uses a triangular rotor spinning inside an oval-shaped chamber instead of pistons moving up and down, making it compact, smooth, and capable of high rpm. It was developed by German engineer Felix Wankel, with early ideas dating back to the 1920s and a first patent in the 1930s, then it was tested in working form in the late 1950s and commercialized in the 1960s, most notably by NSU and later Mazda.