The Navy just got a patent for a very small fission reactor. It is designed to power the UFO-type craft that they patented a couple of months ago. It is VERY fast, travels under water, in the air, and in space. The craft doesn't experience the laws of physics, because it is surrounded by an electro-magnetic force field. It is an advancement of the system on the B2, where the e-m force field reduces the force of the drag from air molecules, so it is much more efficient than the older model aircraft.