Two-cycle, single vane impeller, hinged hub rotary engines are simple embodiments of a new class of engines. The 2-cycle, hinged hub rotary engines have dependently rotating impellers with, interdigitated, alternating hub sections, a hinge like rotation joint. These 2-cycle engines have expansion and exhaust cycles. The intake and compression cycles are performed by a synergistic air compressor (fan or piston type). Fuel and oxidizer (e.g. compressed air, from a synergistic air compressor,) are injected, to create combustion mixtures, and spontaneously ignited to start the expansion cycle in the minimized expansion sector(s).