http://www.flightsafetyaustralia.com/2016/09/positive-charge/

extrait

If you were designing a light aircraft from a truly blank sheet, what propulsion system would you choose? One that needs no air for its operation, giving full power at every altitude; one that is inherently quiet and produces no exhaust emissions; one that is simple to operate and reliable because of its few moving parts; and one that is perfectly scalable allowing one large engine or several smaller engines?