A number of engines usable alone or in combination are taught herein. One engine comprises a housing, a drive shaft mounted within the housing, a first impeller and a second impeller mounted on the drive shaft for movement, and a combustion mediating hub between the second impeller and the first impeller and mounted for movement in both a clockwise and counter-clockwise direction with respect to the drive shaft, where the hub includes an annular plate, a first plurality of blades mounted on a first surface of the annular plate and facing the second impeller and a second plurality of blades mounted on a second, opposing surface of annular plate and facing the first impeller. An ignition source and a fuel source extend through the housing into an area between an outer peripheral wall of the annular plate and an inner wall of the housing.