Lighter than Air?

[YT2095]

I have a Hypothesis, that to ME makes perfect sense, let me begin by assuming we all now WHY and HOW a hot-air balloon works and rises in our atmosphere.

 

now with that established, couldn`t some sort of solid structure be made from light alloys such as Beryllium types, and then have a vacuum created inside it sufficient that the air molecules removed it greater in mass than the structural mass + load, and then let Free, it should Also Rise shouldn`t it?

 

I personally can`t see any reason why in principal it shouldn`t work, maybe I`v missed something?

[swansont]

In principle, yes it would work. In practicality, making a very light material that can stretch and provide compression is possible, while making a light material rigid to resist compression is difficult.

[D H]

The Mythbusters recently floated a lead balloon.

.

[swansont]

But the lead balloon did not rely on a vacuum.

[John Cuthber]

I have wondered about the idea of vacuum baloon before too. It clearly needs a rigid shell.

I also wondered if you could make the rigid shell by putting two balloons together one inside the other, tying the two together with (radial) threads then inflating the space between the 2 "skins".

I think that all designs of balloons become more efficient as they get larger (the weight of the "skin" gets bigger as the square of the radius but the lift ges bigger as the cube, so the net lifting power increases with the size). If that's right then, for a big enough balloon, it should work.

[chemkid]

Perhaps if one worked on the roman arch concept except made it into a sphere? But casting all those tiny wedges perfectly would sure be a pain.

[Mr Skeptic]

I've considered building a non-rigid vacuum-based balloon, using tensile material and compressed air. However, I calculated that the compressed air would outweigh the vacuum's buoyancy. Scaling it up didn't help. That was quite a while ago, so I don't remember the details, and I may have miscalculated it since it was a bit over my head.

 

I don't know about a rigid one, but "rigid" probably takes on a different meaning at such sizes. The structural strength would have to incerase more rapidly than the square of the size if it is to work.

 

In any case, a vacuum-based balloon would be incredibly unsafe, as even a small leak would have horrendous consequences. You'd probably be better off using hot hydrogen.

[DrDNA]

A problem would be engineering enough strength to hold the vacum and the bigger the structure, the more strength that would be necessary.

Perhaps a bunch of tiny little structures coupled together, sort of like a sol gel.......but not porous and not made out of silicon......

[Mr Skeptic]

Now there's an idea. I understand that they have made some aerogels that are (barely) lighter than air when evacuated. If you got a really big one and put a skin on it, it would be an all-solid lighter-than-air craft. However, aerogel is incredibly expensive.

[YT2095]

However, aerogel is incredibly expensive.

 

so were Video recorders, DVD players, Digital watches and clock radios when they 1`st came out, now you can`t Give them away

[CaptainPanic]

The Dutch wikipedia states that researchers have actually made an aerogel with a density of 1 kg/m3 (air is 1.2 kg/m3). It is stated explicitly on the wikipedia site that this aerogel is lighter than air.

 

http://nl.wikipedia.org/wiki/Aerogel

 

The researchers who accomplished this work at the Lawrence Livermore National Laboratory.

 

From their own website (quoted): "We make silica aerogels in a patented process that begins with a partially hydrolyzed silica solution to which we add water, a solvent, and a basic catalyst to form a gel. We then remove the solvent by supercritical conditions in an autoclave and replace it with air. LLNL's process takes a few hours; other methods can take days or weeks. Moreover, the process is flexible enough to let us produce aerogels with a wide range of densities�from 0.7 to 0.001 g/cm3."

 

https://ipo.llnl.gov/technology/profile/aerogel/Terms/index.php

[swansont]

so were Video recorders, DVD players, Digital watches and clock radios when they 1`st came out, now you can`t Give them away

 

You can give me a DVD player. In the interests of empirical data to falsify a hypothesis, of course.

[YT2095]

I have 2 here you`re welcome to, anytime ya wanna pick em up dude

[ydoaPs]

It clearly needs a rigid shell.

 

Wouldn't a rigid frame(shaped like a buckyball, perhaps) with a lightweight airtight skin work just as well as a rigid shell?

[swansont]

Wouldn't a rigid frame(shaped like a buckyball, perhaps) with a lightweight airtight skin work just as well as a rigid shell?

 

Deja vu

[ydoaPs]

Deja vu

 

You should know by now I just read random bits and pieces of random posts