Lighter than Air Craft Using Vacuum

Ever since his earliest times, man must have dreamed of copying the birds; of flying, of gaining mastery over the third dimension of space. The earliest practicable route to achieve the aim of flying was in the use of balloons. The first balloons were hot-air balloons; they relied on the lower density of hot air, compared to that of the surrounding air, to obtain the lift they needed. Balloons are, of course, an application of Archimedes Principle, which states that the upthrust exerted on a body by its surrounding medium is equal to the weight of the medium displaced. With a balloon, this upthrust must be greater than the weight of the balloon structure plus whatever the balloon contains, if the balloon is to rise. In the search for greater lift, the obvious method was to use a light gas. The lightest natural gases are hydrogen and helium. Hydrogen exists as a two-atom molecule with each atom having an atomic weight of 1, giving a molecular weight of 2, and helium as one-atom "molecules", each with an atomic and molecular weight of 4. As the molecular weight of a gas mostly determines its density, hydrogen has half the density of helium. Although hydrogen is lighter, the commercial choice between hydrogen and helium as a balloon lifting gas has been made on other considerations. Helium is non-inflammable, hence safe, but rarer than hydrogen and much more expensive. The airship Hindenburg used hydrogen partly because the Germans found it difficult to buy enough helium. The only lighter possibility in a gas would be monatomic hydrogen, with each hydrogen atom separate, rather than combined in a molecule; such a substance would have twice the lifting power of ordinary hydrogen. Unfortunately, hydrogen is so reactive that no way is known at present to keep it in a monatomic state. So, nothing gives more lift than hydrogen or helium. And in this last sentence is the clue to a possibility which could revolutionise many fields of human activity. This possibility is called the vacuum balloon. Suppose your balloon were filled, not with a light gas, but with a vacuum? In this case, the upthrust is equal to the entire weight of the displaced air, instead of the difference in weights of air and the light gas. This immediately gives a major advantage, in a lifting power greater than any other possible material (or, strictly, nonmaterial!). However, the greatest advantage of the vacuum balloon lies in the way it avoids one of the major limitations of conventional balloons. They leak. The