Vacuum airship
Encyclopedia
A vacuum airship, also known as a vacuum balloon, is a hypothetical airship
that is evacuated
rather than filled with a lighter than air gas such as hydrogen or helium. First proposed by Italian monk Francesco Lana de Terzi
in 1670, the vacuum balloon would be the ultimate expression of displacement lift power.
operates on the principle of buoyancy
where air is the fluid in contrast to a ship
where water
is the fluid. The density of air
at standard temperature and pressure is 1.28 g/L and 1 L of displaced air has sufficient buoyant force to lift 1.28 g. Airships use an airbag to displace a large volume of air; the bag is usually filled with a lightweight gas such as helium
. The total lift generated by an airship is equal to the weight of the air it displaces, regardless of the materials used in its construction or the gas used to fill the airbag; However for flight it is necessary for the total lift capacity to exceed the ship's weight, which includes the weight of the gas used to fill the airbag
Using the molar volume
, the mass of 1 L of helium
(at 1 atmospheres of pressure) is found to be 0.18 g, since every displaced liter provides 1.28g of lift the effective lift is reduced by 14%.
Vacuum airships would theoretically replace the helium gas with a near-vacuum environment and would theoretically be able to provide the full lift potential of displaced air. The main problem with the concept of vacuum airships however is that with a near-vacuum inside the airbag, the outside pressure would exert enormous forces on the airbag and causing it to collapse if not supported. Though it is possible to reinforce the airbag with an internal structure, it is theorized that any structure strong enough to withstand the forces would invariably weigh the vacuum airship down and exceed the total lift capacity of the airship, preventing flight.
and Albert Francis Zahm
. De Bausset published a book on his design and offered $150,000 stock in the Transcontinental Aerial Navigation Company of Chicago. His patent application was eventually denied on the basis that it was "wholly theoretical, everything being based upon calculation and nothing upon trial or demonstration."
Airship
An airship or dirigible is a type of aerostat or "lighter-than-air aircraft" that can be steered and propelled through the air using rudders and propellers or other thrust mechanisms...
that is evacuated
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...
rather than filled with a lighter than air gas such as hydrogen or helium. First proposed by Italian monk Francesco Lana de Terzi
Francesco Lana de Terzi
Francesco Lana de Terzi was an Italian Jesuit, mathematician, naturalist and aeronautics pioneer...
in 1670, the vacuum balloon would be the ultimate expression of displacement lift power.
Principle
An airshipAirship
An airship or dirigible is a type of aerostat or "lighter-than-air aircraft" that can be steered and propelled through the air using rudders and propellers or other thrust mechanisms...
operates on the principle of buoyancy
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
where air is the fluid in contrast to a ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
where water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
is the fluid. The density of air
Density of air
The density of air, ρ , is the mass per unit volume of Earth's atmosphere, and is a useful value in aeronautics and other sciences. Air density decreases with increasing altitude, as does air pressure. It also changes with variances in temperature or humidity...
at standard temperature and pressure is 1.28 g/L and 1 L of displaced air has sufficient buoyant force to lift 1.28 g. Airships use an airbag to displace a large volume of air; the bag is usually filled with a lightweight gas such as helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
. The total lift generated by an airship is equal to the weight of the air it displaces, regardless of the materials used in its construction or the gas used to fill the airbag; However for flight it is necessary for the total lift capacity to exceed the ship's weight, which includes the weight of the gas used to fill the airbag
Using the molar volume
Molar volume
The molar volume, symbol Vm, is the volume occupied by one mole of a substance at a given temperature and pressure. It is equal to the molar mass divided by the mass density...
, the mass of 1 L of helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
(at 1 atmospheres of pressure) is found to be 0.18 g, since every displaced liter provides 1.28g of lift the effective lift is reduced by 14%.
Vacuum airships would theoretically replace the helium gas with a near-vacuum environment and would theoretically be able to provide the full lift potential of displaced air. The main problem with the concept of vacuum airships however is that with a near-vacuum inside the airbag, the outside pressure would exert enormous forces on the airbag and causing it to collapse if not supported. Though it is possible to reinforce the airbag with an internal structure, it is theorized that any structure strong enough to withstand the forces would invariably weigh the vacuum airship down and exceed the total lift capacity of the airship, preventing flight.
Arthur De Bausset
From 1886 to 1900 Arthur De Bausset attempted in vain to raise funds to construct his "vacuum-tube" airship design, but despite early support in the United States Congress, the public became skeptical after the idea was mathematically proved fallacious by Octave ChanuteOctave Chanute
Octave Chanute was a French-born American railway engineer and aviation pioneer. He provided the Wright brothers with help and advice, and helped to publicize their flying experiments. At his death he was hailed as the father of aviation and the heavier-than-air flying machine...
and Albert Francis Zahm
Albert Francis Zahm
Albert Francis Zahm was an early aeronautical experimenter, a professor of physics, and a chief of the Aeronautical Division of the U.S. Library of Congress....
. De Bausset published a book on his design and offered $150,000 stock in the Transcontinental Aerial Navigation Company of Chicago. His patent application was eventually denied on the basis that it was "wholly theoretical, everything being based upon calculation and nothing upon trial or demonstration."