Can a vacuum balloon be built with current material technologies?

Perhaps the goal should be to achieve the best of both worlds. Design the vacuum balloon portion to operate at an altitude where thermal balloons won't. At those altitudes crushing force won't be near as big a problem (I'm guessing). In a way trying to make it work from sea level up would be like trying to make a pool float that could survive being under a mile of seawater.

We live in a dynamic environment, and at the pressure range we typically live at, barring the development of cheap super materials, thermal aircraft are just more suited. That said, I don't see any reason why a staged construction wouldn't be possible. Something that converts from thermal to vacuum at a certain altitude, much like how the F14 changes geometry for different speeds.

One way would just be a folding craft, or maybe a launching craft kind of design. One stage carries the second stage which then launches. It could parachute back down while the first stage could simply land.

This might also be done more simply by designing the shell to accept both vacuum and heated air. Also pumping out air and heating it can both be accomplished electrically. This opens the door for a solar powered craft. Something that would climb through the lower atmosphere like a weather balloon and then gradually pump out the hot air as the pressure drops.

However, I don't know the math. It may be that no such bootstrapping is possible on the grounds that the gains of vacuum are too far away from a thermal craft's maximum altitude. Or put differently it may be that even at max hot air altitude any currently possible vacuum craft would still be too fragile under pressure at that altitude.

Bottom line: The real advantage of vacuum craft is the theoretical ability to float to the very top of the atmosphere; trying to build a pure vacuum craft may be a waste.

Step one in my opinion should be to make a craft that reaches the thermal ceiling and then go from there. According to wiki: On November 26, 2005, Vijaypat Singhania set the world altitude record for highest hot air balloon flight, reaching 21,290 m (69,850 ft). That's 13.2 miles, that's well into the stratosphere, and that was carrying a considerable load. So maybe we should be asking if a vacuum balloon possible at 13.2 miles altitude.

Answer with a question, right?  That's science. :-)
Question: what's the advantage?
What does a cc of hydrogen weigh at sea-level versus a cc of vacuum?
(hint: vacuum weighs zero)
So how does that scale to a cubic meter?  Cubic kilometer?
What's the difference in lift?  Sea-level might not be a practical application but higher up those collapsing forces drop.  How's that change things?
Heck you can hold up anything with a strong enough magnetic field but you'd be better off just building a rail gun if you had all that juice.
Could you ever get enough lift to create a super-high-altitude deck for launching payloads into low-Earth orbit?  Might even be able to do that with hydrogen.
Hey, how about hydrogen/aluminum foam created in a zero-G environment.
Maybe even on the moon.  Lots of H and Al there.
Hydrogen/titanium?  Hydrogen/carbon?
What ever it is, if you make it please promise to give me a ride on it!
Thanks!

A more apt answer might be this: It isnt worth it In effect what you will be doing is getting rid of the weight of the hydrogen and replacing that weight with the material you use to hold out the atmosphere. Plus of course one tiny failure in that system would be catastrophic where a failure in a gas balloon isnt.

The larger you make the balloon, or polyhedron, the greater your displacement to surface area ratio. This means you can make you walls, columns, whatever, thicker and heavier as a percent of it's size. Volume is the third power(cubed) of the radius. Surface area is the second power(squared) of the radius.

You may wish to look at our US patent application 20070001053 (11/517915) (at http://portal.uspto.gov/external/portal/pair enter the verification code and then 11/517915). We propose an evacuated sandwich spherical shell with two thin face sheets and a light core between them. Finite element analysis confirmed that the structure using commercially available materials (e.g., boron carbide face sheets and aluminum honeycomb core) can be light enough to float in air and strong enough to withstand the atmospheric pressure with decent safety factors for strength, buckling, and intracell buckling. Actual manufacturing, while definitely possible, is not easy.

I talked about this with a friend of mine back on Turkey Day. He's a PhD student majoring in Physics at U. W. And like Putzer, my friend likes Buckyballs. Apparently, as the construction material gets heavier, the size must increase to overcome the weight. So use aluminum for minimal weight and maximum stiffness. Skin the thing in whatever you like, and paint it black to absorb thermal energy from the sun. It will lift itself. For further research, take a look at Buckminster Fuller, Buckyballs, Dimaxian House, and geodesic dome.

The simple answer is "no". Using modern materials, a balloon-shaped object containing a vacuum would be too heavy to be lifted.

Maybe if it was made of a light weight, yet rigid enough plastic that would not succumb to atmospheric pressure.

Perhaps buckyballs?

it has been suggested that plasma fields or magnetically held metal can be used. but plasma is complicated and relies on enormous amounts of electricity to contain them, and the magnet thing is complicated and has never been attempted