Vacuum airship

First proposed by Italian Jesuit priest Francesco Lana de Terzi in 1670,[1] the vacuum balloon would be the ultimate expression of lifting power per volume displaced.

[2]) 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 general public was skeptical.

Illinois historian Howard Scamehorn reported that Octave Chanute and Albert Francis Zahm "publicly denounced and mathematically proved the fallacy of the vacuum principle"; however, the author does not give his source.

[3] De Bausset published a book on his design[4] and offered $150,000 stock in the Transcontinental Aerial Navigation Company of Chicago.

[5][6] 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.

"[7] In 1921, Lavanda Armstrong disclosed a composite wall structure with a vacuum chamber "surrounded by a second envelope constructed so as to hold air under pressure, the walls of the envelope being spaced from one another and tied together", including a honeycomb-like cellular structure.

[8] In 1983, David Noel discussed the use of a geodesic sphere covered with plastic film and "a double balloon containing pressurized air between the skins, and a vacuum in the centre".

[9] In 1982–1985 Emmanuel Bliamptis elaborated on energy sources and use of "inflatable strut rings".

[10] However, the double-wall design proposed by Armstrong, Noel, and Bliamptis would not have been buoyant.

In order to avoid collapse, the air between the walls must have a minimum pressure (and therefore also a density) proportional to the fraction of the total volume occupied by the vacuum section, preventing the total density of the craft from being less than the surrounding air.

[citation needed] In 2004–2007, to address strength to weight ratio issues, Akhmeteli and Gavrilin addressed choice of four materials, specifically I220H beryllium (elemental 99%), boron carbide ceramic, diamond-like carbon, and 5056 Aluminum alloy (94.8% Al, 5% Mg, 0.12% Mn, 0.12%Cr) in a honeycomb double layer.

[11] In 2021, they extended this research; a "finite element analysis was employed to demonstrate that buckling can be prevented", focusing on a "shell of outer radius R > 2.11 m containing two boron carbide face skins of thickness 4.23 x 10−5 R each that are reliably bonded to an aluminum honeycomb core of thickness 3.52 x 10−3 R".

The density of air at standard temperature and pressure is 1.28 g/L, so 1 liter of displaced air has sufficient buoyant force to lift 1.28 g. Airships use a bag to displace a large volume of air; the bag is usually filled with a lightweight gas such as helium or hydrogen.

The total lift generated by an airship is equal to the weight of the air it displaces, minus the weight of the materials used in its construction, including the gas used to fill the bag.

Vacuum airships would replace the lifting gas with a near-vacuum environment.

This enormous imbalance of forces would cause the airbag to collapse unless it were extremely strong (in an ordinary airship, the force is balanced by the pressure of the lifting gas, making this unnecessary).

Thus the difficulty is in constructing an airbag with the additional strength to resist this extreme net force, without weighing the structure down so much that the greater lifting power of the vacuum is negated.

[2][11] From the analysis by Akhmeteli and Gavrilin:[11] The total force on a hemi-spherical shell of radius

Pa, of the same order of magnitude as the compressive strength of aluminum alloys.

Substituting the earlier expression gives a necessary condition for a feasible vacuum balloon shell: The requirement is about

[11] A vacuum airship should at least float (Archimedes law) and resist external pressure (strength law, depending on design, like the above R. Zoelli's formula for sphere).

are pressure and density of standard Earth atmosphere at sea level,

are molar mass (kg/kmol) and temperature (K) of atmosphere at floating area.

Of all known planets and moons of the Sun system only the Venusian atmosphere has

In Edgar Rice Burroughs's novel Tarzan at the Earth's Core, Tarzan travels to Pellucidar in a vacuum airship constructed of the fictional material Harbenite.

In Passarola Rising, novelist Azhar Abidi imagines what might have happened had Bartolomeu de Gusmão built and flown a vacuum airship.

Spherical vacuum body airships using the Magnus effect and made of carbyne or similar superhard carbon are glimpsed in Neal Stephenson's novel The Diamond Age.

In Maelstrom[14] and Behemoth:B-Max, author Peter Watts describes various flying devices, such as "botflies" (named after the botfly) and "lifters" that use "vacuum bladders" to keep them airborne.

In Feersum Endjinn by Iain M. Banks, a vacuum balloon is used by the narrative character Bascule in his quest to rescue Ergates.

Vacuum dirigibles (airships) are also mentioned as a notable engineering feature of the space-faring utopian civilisation The Culture in Banks' novel Look to Windward, and the vast vacuum dirigible Equatorial 353 is a pivotal location in the final Culture novel, The Hydrogen Sonata.