Some field propulsion systems are based on the solution of General Relativity Theory and are related to the connection between gravity and electromagnetic field. For example, Robert Forward proposed a gravity machine working according to the Einstein's General Relativity Theory, which requires ultra dense matter with the density of a dwarf star to produce useful thrust, but the proposed theoretical scheme cannot be realized by conventional technologies. The authors propose several concepts of a gravity machine utilizing an intense electromagnetic field that produces sufficient thrust to propel the spaceship, in accordance with Einstein's General Relativity Theory.