Rotary engines (also known as Wankel engines and Wankel rotary engines) are quite different from piston or "reciprocating" engines. One of the distinguishing features is that they don't need valves to ...

The rotary valve also means that the blockages caused by conventional poppet valves are not an issue as poppet valves are not needed in Alpha-Otto’s design. As the cylinder drops during combustion, ...