A rotary internal combustion engine includes outer and inner housings defining an enclosure therebetween, and first and second side housings disposed on opposite sides of the outer housing. The inner housing is rotatable relative to the outer housing and at least two barriers divide the enclosure into a combustion chamber and an exhaust chamber. At least one barrier is rotatable relative to at least one other barrier and at least one barrier comprises a retractable barrier mounted along a pivot axis and is pivotable between an extended position and a retracted position. An intake port, exhaust port, and ignition source are also provided. The rotary internal combustion engine further includes a cylindrical stationary shaft disposed inside the inner housing and oriented substantially coaxially with the inner housing. The stationary shaft has an intake opening configured to be intermittently fluidly connected with the intake port.