US Patent 7165388 Propulsion device with enclosed plenum

A propulsion device contains a working mass within an enclosed plenum, where the working mass is circulated through the plenum to produce a net force vector. The working mass is accelerated around a first bend or change in direction within the plenum by a working mass driver. The temperature of the working mass is then reduced and the working mass is slowed. The working mass is then accelerated around a second bend or change in direction within the plenum resulting in two opposing force vectors. When combined, the two opposing force vectors produce a net force, and thus, acceleration of the propulsion device.