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Airship to Orbit question
I was reading about the airship to orbit idea, and how it is probably
impossible. This got me to thinking, are there any materials like carbon nanotubes that could concievably be used produce a large volume vacuum container or "balloon"? I recently asked one of those ask-a-physicist sites and was told that an airtight "ballon" with a volume of near vacuum should float even higher than a hydrogen balloon, but that no existing materials are at the same time strong enough and light enough to ever produce such a device. Such a device should be much simpler and cheaper to create than a space elevator, and could (hopefully) be mass produced. So is this is just a crazy idea, or is it possible? |
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Airship to Orbit question
Chance wrote: So is this is just a crazy idea, [[a vacuum-filled balloon]] or is it possible? It's neither. It's not crazy and it's not possible with any balloon current flight profile. Vacuum is cheaper than helium. But most people don't realize the implosive force of one bar on a vacuum container. A bar is 14.7 pounds per square inch, multiplied by the hundreds of thousands of square inches on the surface of a large lifting tank. So, the reinforced, honeycombed vacuum container would have to be lifted to the stratosphere and then vacuumed-out where it could rise to near space but not, of course, to space, which is a vacuum itself. Similar to a two stage rocket, this would be a "two-stage balloon." In practice, a partial vacuum would be drawn slowly during ascension so as to maintain a safe pressure differential on the vacuum tank. |
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Airship to Orbit question
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1 In article .com, "beanstalkr" writes: It's neither. It's not crazy and it's not possible with any balloon current flight profile. Vacuum is cheaper than helium. But most people don't realize the implosive force of one bar on a vacuum container. A bar is 14.7 pounds per square inch, multiplied by the hundreds of thousands of square inches on the surface of a large lifting tank. It also doesn't help much --- hydrogen has about 1/18 the density of air at a given pressure. Vacuum, of course, has 0/18 the density of air. So by using a vacuum balloon, you end up making your life considerably more complex for only an extra 6% boost in lifting capability. - -- +- David Given --McQ-+ | | Quidquid latine dictum sit, altum viditur. | ) | +- www.cowlark.com --+ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFDqB4rf9E0noFvlzgRAtg0AJ9XeyJdkKrmHDA4T22r2U x9MeNJIgCgk5oM qEBYGp+Hx1pgvNLsyIF7wCk= =AHSN -----END PGP SIGNATURE----- |
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Airship to Orbit question
Thanks all for the replies. =-) I see, so the extra 6% boost doesn't
get you high enough to make the scheme practical. (if it was even possible). So, what altitude would it be necessary to achieve in order for electric propulsion to overcome drag? |
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