content: The idea is 60 years old. The best usage for the MHD is combined with a turbo reactor. You transform part of the energy provided by the reactor to produce electricity. This energy is used to remove the friction from the air. At really high machs, the benefit is huge, and it's the only way to go past 7 machs whith a regular turbo reactor. Since you are covered with plasma, you are also undectable by radars. It's the technology used by the top secret aircraft aurora.