Very old technologies

[Helioaeolian]

First-time poster anywhere. Sorry if this runs long, but I've been digesting everything that went before.

I've got a suggestion for making metal float that comes from a 17th century illustration I saw in a history of flight. It showed a wooden boat suspended from four copper spheres that enclosed a vacuum. It's the Archimedes principle. A steel ship floats by displacing water with air, so an airship should hover by displacing air with a vacuum.

The problem, of course, is atmospheric pressure. A metal sphere strong enough to enclose that much vacuum is too heavy to float. Unless you could make it out of a super-light metal. Something like titanium foam. Like styrofoam is to styrene, so titanium foam is to titanium. Stronger than steel, but lighter that balsa wood.

You can't make this stuff on earth because of the effects of gravity. But you can in space. Forge your tank in orbit, enclose enough vacuum to make it float, then re-enter the atmosphere and bring it down to earth. The whole thing hovers, and without fuel.

And this adds an extra bonus for the modeler: A scorched heat shield.

Foam the titanium with helium. The armor's still lighter than air, and because helium's an inert gas, it extinguishes shaped charges.

Fill the enclosed space with hydrogen. It's still lighter than air, and there's your fuel for the cold fusion engine.

And all of it is basic physics.

[Dr. Yo]

Venting and ballasting might present problems, but in all, its a neat
concept. Welcome to the boards!

[Andrew Gorman]

Here a CGI vacuum airship from Russia if anyone needs some inspiration:
http://www.rusring.net/~levin/levin3d/dz.htm

[publiusr]

Here is the initial concept
http://en.wikipedia.org/wiki/Vacuum_airship
http://www.hovertech.com/home/research/ ... blimp.html
http://forums.theregister.co.uk/post/267049
http://www.settledistrictu3a.org.uk/dh/ ... 5.600.html
http://www.aoi.com.au/Originals/VacuumBalloon.pdf

Discussion on the Russian design
http://www.airshipmodeler.com/forums/ar ... t-366.html

Nice designs
http://tvtropes.org/pmwiki/pmwiki.php/M ... otherWorld
http://vacuadirigibles.com/default.aspx
http://tmp2.wikia.com/wiki/Aquarian_Airship
http://airshipworld.blogspot.com/2007_0 ... chive.html

The strato-cruiser
http://www.dezeen.com/2007/10/08/strato ... l-j-brown/

Model
http://www.etsy.com/listing/35202931/st ... -dirigible

This opens a file
sci.esa.int/science-e/www/object/doc.cfm?fobjectid=46147 · Cached page

Alabama Statellite
http://www.space.com/businesstechnology ... 00520.html


Umm...
http://guthvenus.tripod.com/airship-02.htm
http://www.bing.com/search?q=vacuum+air ... FORM=PERE3