Distinction between "rotary" and "radial" engines
A rotary engine is essentially a standard Otto cycle engine, with cylinders arranged radially around a central crankshaft just like a conventional 展开

Millet
Félix Millet showed a 5-cylinder rotary engine built into a bicycle wheel at the Exposition Universelle in Paris in 1889. Millet had patented the … 展开

Besides the configuration of cylinders moving around a fixed crankshaft, several different engine designs are also called rotary engines. The most notable pistonless rotary engine, the Wankel rotary engine has been used by NSU in the Ro80 car, … 展开

• Paris Musee de l'Air combination of "rotary" and "radial" engine-function kinetic display
• Smithsonian NASM Gnôme Omega No.1 page
• Smithsonian NASM Le Rhône 9J page 展开

Monosoupape rotaries
It is often asserted that rotary engines had no throttle and hence power could only be reduced by 展开

Although rotary engines were mostly used in aircraft, a few cars and motorcycles were built with rotary engines. Perhaps the first was the 展开

• Petrol engine
• Monosoupape engine
• Manly–Balzer engine
• Nutating disc engine
• Quasiturbine 展开