I’m not sure what you would call it, but what I’m thinking about is a synthesis of several machines that gives you a “repulsor” type effect. It’s about as stable as trying to float one magnet atop another (which is to say… very unstable). It is what I think the notsee bell device was, and amounts to a lawn mower engine connected to a wimshurst machine to an “alternator” (not in the automotive sense, but in the selecting alternating charge sense). There are hints of this effect from the 1800’s, and in the less-heralded details of the bob lazar story.