Abstract: A rotary internal-combustion engine having a pair of rotor elements fixed to parallel shafts extending coaxially in cylindrical cavities and confronting each other in an intersection region. Each of the rotor elements has a generally cylindrical outer surface spaced from the interior wall of the corresponding cylindrical cavity, and a plurality of sealing vane structures project radially outwardly from the cylindrical outer surfaces to sealingly confront the respective cylindrical cavity interior walls. Between adjacent sealing vane structures combustion charge interspaces and air charge interspaces are alternately defined. The rotor elements are synchronized with respect to each other such that the combustion charge interspaces of one of the rotor elements confront corresponding combustion charge interspaces of the other of the rotor elements. Similarly, the air charge interspaces of the one rotor element confront corresponding air charge interspaces of the other rotor element.