A fairly strange comment. 1) Engines requiring "tons of mercury" (and, presumably, more tons of thorium etc. dissolved in it) are likely to be heavier than com

A fairly strange comment. 1) Engines requiring "tons of mercury" (and, presumably, more tons of thorium etc. dissolved in it) are likely to be heavier than competing technologies. For aircraft use, it's a significant drawback. 2)An engine that is based on heavy spinning parts might perhaps drive propellers, but military propeller aircraft have stopped being secret futuristic tech between 80 and 100 years ago. 3) Thorium is quite stable. How could its decay be exploited as a power source? Other radioactive elements, like the plutonium isotopes used in space probes (for heat production) offer a better compromise between stable enough to store and use as fuel and unstable enough to be weight-efficient. 4) Patent US20120105181A1 is illustrated with an actual Levitron toy. I'd assume it's a joke, but US20130175895A1 by the same author is a bit more interesting and along the same lines, and it has the appearance of egregious crackpot material (competing in the prestigious free energy/perpetual motion division).