Personal flying machines are a standard dream of the future. Hoverboards, promised in 1985's Back To The Future Part II lifted their riders off the ground and carried them on a thin cushion of air through the world. We have many more hoverboard-like devices now, but most are on wheels, or levitate over special magnetic railings. Zapata Industries' Flyboard aircraft is, as the name suggests, a board that actually flies. And now a major security company plans to buy it, and maybe even sell it to the military.