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How to build a floating city.
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eripe
Mar 19, 2013, 12:51:26 AM3/19/13
to
Just had an idea to make foam with a density of say 0,2 kg/m3 and a compression strength of 0,2 MPa.
(it gives a specific strength of 1, by comparison, carbon fibers are at 2,5 so it is theoriticaly possible with current day materials even though the fabrication method is handwaving)
This foam can now be coated with airtight paint and the air sucked out to make a vacuum. The structure will now lift as if filled by helium, only better.
There is no particular requirement as to the shape so anything and pretty much any zize will float.
But before I dream of cruising the world in 2 km long Star Destroyer replica, does anyone see any problems with it?
(it gives a specific strength of 1, by comparison, carbon fibers are at 2,5 so it is theoriticaly possible with current day materials even though the fabrication method is handwaving)
This foam can now be coated with airtight paint and the air sucked out to make a vacuum. The structure will now lift as if filled by helium, only better.
There is no particular requirement as to the shape so anything and pretty much any zize will float.
But before I dream of cruising the world in 2 km long Star Destroyer replica, does anyone see any problems with it?
Andrew Plotkin
Mar 19, 2013, 1:44:51 AM3/19/13
to
Here, eripe <erip...@gmail.com> wrote:
> Just had an idea to make foam with a density of say 0,2 kg/m3 and a
> compression strength of 0,2 MPa.
>
> (it gives a specific strength of 1, by comparison, carbon fibers
> are at 2,5 so it is theoriticaly possible with current day materials
> even though the fabrication method is handwaving)
>
> This foam can now be coated with airtight paint and the air sucked
> out to make a vacuum. The structure will now lift as if filled by
> helium, only better.
Helium is way cheaper than unobtainium, and lifts nearly as well as
> Just had an idea to make foam with a density of say 0,2 kg/m3 and a
> compression strength of 0,2 MPa.
>
> (it gives a specific strength of 1, by comparison, carbon fibers
> are at 2,5 so it is theoriticaly possible with current day materials
> even though the fabrication method is handwaving)
>
> This foam can now be coated with airtight paint and the air sucked
> out to make a vacuum. The structure will now lift as if filled by
> helium, only better.
vacuum.
If you pay attention to materials, you can probably use hydrogen.
(Sure, it gets a bad rap, but you want to avoid setting your vehicle
on fire *anyway*.)
--Z
--
"And Aholibamah bare Jeush, and Jaalam, and Korah: these were the borogoves..."
*
eripe
Mar 19, 2013, 10:49:01 AM3/19/13
to
>
> Helium is way cheaper than unobtainium, and lifts nearly as well as
>
> vacuum.
>
Not unobtanium - If you wind basalt fibers into a 180 mm wide pipe with a 1,5 mm thick shell, this pipe can support 4 sqm of vacuum pressure. If you put pipes like this in a tetrahedron spaceframe 2 meters on the side, you can make a vacuum balloon.
> Helium is way cheaper than unobtainium, and lifts nearly as well as
>
> vacuum.
>
Its a lot of work though, thats why i prefer someone to make a foam you can just stack up and paint.
>
>
> If you pay attention to materials, you can probably use hydrogen.
>
> (Sure, it gets a bad rap, but you want to avoid setting your vehicle
>
> on fire *anyway*.)
Wayne Throop
Mar 18, 2013, 11:02:04 PM3/18/13
to
: eripe <erip...@gmail.com>
: If you wind basalt fibers into a 180 mm wide pipe with a 1,5 mm thick
helium, why not use tension instead of compression, and thus a lifting
gas instead of foam-and-vacuum? If it performs "as if filled by helium",
why not use helium? You say "only better", but what's better about it?
What if something bumps into it and scuffs the paint, or hits it hard
enough to poke a hole into the foam (of various depths)? I suppose
the notion is to compartmentalize as with dirigibles, but still,
what makes it better?
Usually, vacuum doesn't lift enough better than hydrogen or helium
to make much difference. What makes this application different?
"Tenser" said the tensor! Tenser said the tensor!
Compression, apprehension and dissension have begun!
: If you wind basalt fibers into a 180 mm wide pipe with a 1,5 mm thick
: shell, this pipe can support 4 sqm of vacuum pressure. If you put
: pipes like this in a tetrahedron spaceframe 2 meters on the side, you
: can make a vacuum balloon.
The question is, why make a vacuum balloon which performs no better than
: pipes like this in a tetrahedron spaceframe 2 meters on the side, you
: can make a vacuum balloon.
helium, why not use tension instead of compression, and thus a lifting
gas instead of foam-and-vacuum? If it performs "as if filled by helium",
why not use helium? You say "only better", but what's better about it?
What if something bumps into it and scuffs the paint, or hits it hard
enough to poke a hole into the foam (of various depths)? I suppose
the notion is to compartmentalize as with dirigibles, but still,
what makes it better?
Usually, vacuum doesn't lift enough better than hydrogen or helium
to make much difference. What makes this application different?
"Tenser" said the tensor! Tenser said the tensor!
Compression, apprehension and dissension have begun!
Lars Kecke
Mar 19, 2013, 11:49:07 AM3/19/13
to
Am 19.03.2013 05:51, schrieb eripe:
> Just had an idea to make foam with a density of say 0,2 kg/m3 and a
> compression strength of 0,2 MPa.
>
> (it gives a specific strength of 1, by comparison, carbon fibers are
> at 2,5 so it is theoriticaly possible with current day materials even
> though the fabrication method is handwaving)
>
> This foam can now be coated with airtight paint and the air sucked
> out to make a vacuum. The structure will now lift as if filled by
> helium, only better.
The lift per volume is not much better (something like 28/24 compared to
> Just had an idea to make foam with a density of say 0,2 kg/m3 and a
> compression strength of 0,2 MPa.
>
> (it gives a specific strength of 1, by comparison, carbon fibers are
> at 2,5 so it is theoriticaly possible with current day materials even
> though the fabrication method is handwaving)
>
> This foam can now be coated with airtight paint and the air sucked
> out to make a vacuum. The structure will now lift as if filled by
> helium, only better.
Helium), and it will probably be a pain to suck the air out of the foam.
> There is no particular requirement as to the shape so anything and
> pretty much any zize will float.
>
> But before I dream of cruising the world in 2 km long Star Destroyer
> replica, does anyone see any problems with it?
Catch a gust and your whole ship breaks under the shear force.
Lars
Greg Goss
Mar 19, 2013, 1:04:34 PM3/19/13
to
Andrew Plotkin <erky...@eblong.com> wrote:
>Helium is way cheaper than unobtainium, and lifts nearly as well as
>vacuum.
Aren't there serious concerns about running the helium supply to
>Helium is way cheaper than unobtainium, and lifts nearly as well as
>vacuum.
zilch? I've seen articles that the current helium pricing depends
largely on US war-blimp supplies being run to zero since we no longer
use such things.
--
I used to own a mind like a steel trap.
Perhaps if I'd specified a brass one, it
wouldn't have rusted like this.
Andrew Plotkin
Mar 19, 2013, 3:47:57 PM3/19/13
to
Here, Greg Goss <go...@gossg.org> wrote:
> Andrew Plotkin <erky...@eblong.com> wrote:
>
> >Helium is way cheaper than unobtainium, and lifts nearly as well as
> >vacuum.
>
> Aren't there serious concerns about running the helium supply to
> zilch?
Yes. But it's still better than the scrith supply. :)
> Andrew Plotkin <erky...@eblong.com> wrote:
>
> >Helium is way cheaper than unobtainium, and lifts nearly as well as
> >vacuum.
>
> Aren't there serious concerns about running the helium supply to
> zilch?
(Yeah, I saw that you don't actually need scrith for this. Still.)
eripe
Mar 19, 2013, 9:05:29 PM3/19/13
to
>
> The question is, why make a vacuum balloon which performs no better than
>
> helium, why not use tension instead of compression, and thus a lifting
>
> gas instead of foam-and-vacuum?
"Its gonna hang there the same way a brick dosent"
If it performs "as if filled by helium",
>
> why not use helium? You say "only better", but what's better about it?
>
> What if something bumps into it and scuffs the paint, or hits it hard
>
> enough to poke a hole into the foam (of various depths)? I suppose
>
> the notion is to compartmentalize as with dirigibles, but still,
>
> what makes it better?
If you are quick, you can even get down to the hole and slap a patch on.
(In both cases its still better than a plane with a hole in it.)
>The lift per volume is not much better (something like 28/24 compared to
>Helium), and it will probably be a pain to suck the air out of the foam.
Anyway, that pain comes nowhere near the pain you feel when paying for a boatload of Helium, and will have to keep paying to keep up with leakage.
> The same thing that killed the R38, the R101, the Akron and the Macon.
The gas boat just has a thin shell to cary all the wind load, I have a solid, it will be orders of magnitude stonger.
Wayne Throop
Mar 19, 2013, 11:17:06 PM3/19/13
to
: eripe <erip...@gmail.com>
: If you poke a hole in a gas boat, you loose your shape immidiatly and
don't work after all?
: The gas boat just has a thin shell to cary all the wind load, I have a
: If you poke a hole in a gas boat, you loose your shape immidiatly and
: go down like a rock.
Really? You mean the multiple lifting cells dirigibles had
don't work after all?
: The gas boat just has a thin shell to cary all the wind load, I have a
: solid, it will be orders of magnitude stonger.
I doubt the square-cube law can be escaped so easily.
Mark Zenier
Mar 19, 2013, 11:38:44 PM3/19/13
to
In article <aqrk4v...@mid.individual.net>,
set up in the Texas natural gas fields to lift the blimps of WW II.
And the free market fundamentalists in the Republican party just cannot
tolerate that.
Don't expect your MRI scans to get any cheaper.
Mark Zenier mze...@eskimo.com
Googleproofaddress(account:mzenier provider:eskimo domain:com)
Greg Goss <go...@gossg.org> wrote:
>Andrew Plotkin <erky...@eblong.com> wrote:
>
>>Helium is way cheaper than unobtainium, and lifts nearly as well as
>>vacuum.
>
>Aren't there serious concerns about running the helium supply to
>zilch? I've seen articles that the current helium pricing depends
>largely on US war-blimp supplies being run to zero since we no longer
>use such things.
The problem is that the best helium supply comes from a socialist system
>Andrew Plotkin <erky...@eblong.com> wrote:
>
>>Helium is way cheaper than unobtainium, and lifts nearly as well as
>>vacuum.
>
>Aren't there serious concerns about running the helium supply to
>zilch? I've seen articles that the current helium pricing depends
>largely on US war-blimp supplies being run to zero since we no longer
>use such things.
set up in the Texas natural gas fields to lift the blimps of WW II.
And the free market fundamentalists in the Republican party just cannot
tolerate that.
Don't expect your MRI scans to get any cheaper.
Mark Zenier mze...@eskimo.com
Googleproofaddress(account:mzenier provider:eskimo domain:com)
John F. Eldredge
Mar 20, 2013, 2:44:45 PM3/20/13
to
separate it out from natural gas supplies elsewhere (more expensive,
since it is at lower concentration elsewhere), or to separate it out from
the atmosphere (even more expensive, as helium has the lowest boiling
point of any element).
--
John F. Eldredge -- jo...@jfeldredge.com
"Reserve your right to think, for even to think wrongly
is better than not to think at all." -- Hypatia of Alexandria
Sea Wasp (Ryk E. Spoor)
Mar 20, 2013, 3:04:34 PM3/20/13
to
On 3/20/13 2:44 PM, John F. Eldredge wrote:
> Once this particular helium supply is exhausted, the choice will be to
> separate it out from natural gas supplies elsewhere (more expensive,
> since it is at lower concentration elsewhere), or to separate it out from
> the atmosphere (even more expensive, as helium has the lowest boiling
> point of any element).
>
Why is it that that particular field has a lot of helium in it and
> Once this particular helium supply is exhausted, the choice will be to
> separate it out from natural gas supplies elsewhere (more expensive,
> since it is at lower concentration elsewhere), or to separate it out from
> the atmosphere (even more expensive, as helium has the lowest boiling
> point of any element).
>
others don't? Does anyone know? My first reaction would be that it would
indicate a HELL of a lot of radium, or some other alpha emitter, right
inside or below the gas field.
--
Sea Wasp
/^\
;;;
Website: http://www.grandcentralarena.com Blog:
http://seawasp.livejournal.com
John F. Eldredge
Mar 20, 2013, 11:34:38 PM3/20/13
to
On Wed, 20 Mar 2013 15:04:34 -0400, Sea Wasp (Ryk E. Spoor) wrote:
> On 3/20/13 2:44 PM, John F. Eldredge wrote:
>
>> Once this particular helium supply is exhausted, the choice will be to
>> separate it out from natural gas supplies elsewhere (more expensive,
>> since it is at lower concentration elsewhere), or to separate it out
>> from the atmosphere (even more expensive, as helium has the lowest
>> boiling point of any element).
>>
>>
> Why is it that that particular field has a lot of helium in it and
> others don't? Does anyone know? My first reaction would be that it would
> indicate a HELL of a lot of radium, or some other alpha emitter, right
> inside or below the gas field.
Yes, I have wondered what the radon content of that natural gas flow is.
> On 3/20/13 2:44 PM, John F. Eldredge wrote:
>
>> Once this particular helium supply is exhausted, the choice will be to
>> separate it out from natural gas supplies elsewhere (more expensive,
>> since it is at lower concentration elsewhere), or to separate it out
>> from the atmosphere (even more expensive, as helium has the lowest
>> boiling point of any element).
>>
>>
> Why is it that that particular field has a lot of helium in it and
> others don't? Does anyone know? My first reaction would be that it would
> indicate a HELL of a lot of radium, or some other alpha emitter, right
> inside or below the gas field.
eripe
Mar 29, 2013, 9:58:25 PM3/29/13
to
On Wednesday, March 20, 2013 10:17:06 AM UTC+7, Wayne Throop wrote:
>
> : If you poke a hole in a gas boat, you loose your shape immidiatly and
>
> : go down like a rock.
>
>
>
> Really? You mean the multiple lifting cells dirigibles had
>
> don't work after all?
I was thinking of a smaller size blimp. For multi cell bodies you would retain your shape like you say.
>
> : If you poke a hole in a gas boat, you loose your shape immidiatly and
>
> : go down like a rock.
>
>
>
> Really? You mean the multiple lifting cells dirigibles had
>
> don't work after all?
But if you do get a hole and loose your helium your helium, the only way to replace it is a new supply, which might be hard to get in the middle of desert. With vacuum you patch it up, suck out the air and are ready to go. All you need is power for the pump, which should be plentyfull from solar power.
(I suppose a landing in the ocean could produce Hydrogen for replacement, but you need some serious water treatment to do that.)
>
>
>
> : The gas boat just has a thin shell to cary all the wind load, I have a
>
> : solid, it will be orders of magnitude stonger.
>
>
>
> I doubt the square-cube law can be escaped so easily.
The difference in bending resistance is 1/4*r/t
r - radius of boat
t - thickness of skin
So for the Goodyear blimp with a radius of 7500 mm and a fabric thickness of 0,09 mm the foam would be 20800 times more resistant.
The fabric (polyurethane) is about 200 times stronger than my foam, but the vacuum boat would still be 100 times stronger.
If that is not enough, I can coat it with a thin layer of glass fiber reinforced polyester, which is at least 10 times stronger than than blimp fabric.
The main advantage however is the ease of fabrication. Stack, extrude, cut or blow the foam into the shape you like, coat it, suck, and off you go. If its of balance you add or remove some where it is needed.
You can even have your compartments inside the body, just dig a tunnel and mine your cave, then give a coat of paint.
Remus Shepherd
Apr 2, 2013, 9:49:32 AM4/2/13
to
Lars Kecke <lars...@googlemail.com> wrote:
> Am 19.03.2013 05:51, schrieb eripe:
> > This foam can now be coated with airtight paint and the air sucked
> > out to make a vacuum. The structure will now lift as if filled by
> > helium, only better.
> The lift per volume is not much better (something like 28/24 compared to
> Helium), and it will probably be a pain to suck the air out of the foam.
You grow the foam in orbital vacuum and ship the lighter-than-air hulls
> Am 19.03.2013 05:51, schrieb eripe:
> > This foam can now be coated with airtight paint and the air sucked
> > out to make a vacuum. The structure will now lift as if filled by
> > helium, only better.
> The lift per volume is not much better (something like 28/24 compared to
> Helium), and it will probably be a pain to suck the air out of the foam.
down.
We've talked about vacuum balloons/dirigibles on this newsgroup many times
before. The consensus always seems to arrive at the opinion that they're
feasible but not viable for economic reasons.
> > There is no particular requirement as to the shape so anything and
> > pretty much any zize will float.
> >
> > But before I dream of cruising the world in 2 km long Star Destroyer
> > replica, does anyone see any problems with it?
> The same thing that killed the R38, the R101, the Akron and the Macon.
> Catch a gust and your whole ship breaks under the shear force.
oblong, hull shapes. They can be arbitrarily large, however -- or at least
to the point where you start worrying about stress due to thermal factors.
... ...
Remus Shepherd <re...@panix.com>
New Webcomic: Genocide Man http://www.genocideman.com/
Life is funny. Death is funnier. Mass slaughter can be hilarious.
Doc O'Leary
Apr 2, 2013, 11:53:18 AM4/2/13
to
In article <kjenlc$pcr$1...@reader1.panix.com>,
be more of a pain. Has anyone even tried to deorbit any sort of balloon
yet? My assumption is that the larger structure is more fragile, and
the stresses will be higher despite it being lighter than air, but it
isn't quite intuitive that that is true.
Fragility would also be a serious factor in every day use. There will
inevitably be punctures, and it's unlikely you're going to send it back
into space just for repairs. There's really no avoiding on-planet
construction.
--
iPhone apps that matter: http://appstore.subsume.com/
My personal UDP list: 127.0.0.1, localhost, googlegroups.com, theremailer.net,
and probably your server, too.
Remus Shepherd <re...@panix.com> wrote:
> Lars Kecke <lars...@googlemail.com> wrote:
> > Am 19.03.2013 05:51, schrieb eripe:
> > > This foam can now be coated with airtight paint and the air sucked
> > > out to make a vacuum. The structure will now lift as if filled by
> > > helium, only better.
>
> > The lift per volume is not much better (something like 28/24 compared to
> > Helium), and it will probably be a pain to suck the air out of the foam.
>
> You grow the foam in orbital vacuum and ship the lighter-than-air hulls
> down.
Orbiting raw materials and deorbiting the finished product is likely to
> Lars Kecke <lars...@googlemail.com> wrote:
> > Am 19.03.2013 05:51, schrieb eripe:
> > > This foam can now be coated with airtight paint and the air sucked
> > > out to make a vacuum. The structure will now lift as if filled by
> > > helium, only better.
>
> > The lift per volume is not much better (something like 28/24 compared to
> > Helium), and it will probably be a pain to suck the air out of the foam.
>
> You grow the foam in orbital vacuum and ship the lighter-than-air hulls
> down.
be more of a pain. Has anyone even tried to deorbit any sort of balloon
yet? My assumption is that the larger structure is more fragile, and
the stresses will be higher despite it being lighter than air, but it
isn't quite intuitive that that is true.
Fragility would also be a serious factor in every day use. There will
inevitably be punctures, and it's unlikely you're going to send it back
into space just for repairs. There's really no avoiding on-planet
construction.
--
iPhone apps that matter: http://appstore.subsume.com/
My personal UDP list: 127.0.0.1, localhost, googlegroups.com, theremailer.net,
and probably your server, too.
Remus Shepherd
Apr 2, 2013, 9:44:22 PM4/2/13
to
Doc O'Leary <drolear...@1q2013.subsume.com> wrote:
kilometer across you could plate it in ten-centimeter steel; the total
density will still be lighter than helium.
Note also that punctures don't matter much. It's a foam of carbon
nanotubes. At most you'll lose the lift from whatever material you gouge
out of it, although that wound will then be vulnerable to further damage
until you bolt more steel over it.
> Remus Shepherd <re...@panix.com> wrote:
> Orbiting raw materials and deorbiting the finished product is likely to
> be more of a pain. Has anyone even tried to deorbit any sort of balloon
> yet? My assumption is that the larger structure is more fragile, and
> the stresses will be higher despite it being lighter than air, but it
> isn't quite intuitive that that is true.
> Fragility would also be a serious factor in every day use. There will
> inevitably be punctures, and it's unlikely you're going to send it back
> into space just for repairs. There's really no avoiding on-planet
> construction.
We're talking about a structure of arbitrary size. If it's a sphere one
> Orbiting raw materials and deorbiting the finished product is likely to
> be more of a pain. Has anyone even tried to deorbit any sort of balloon
> yet? My assumption is that the larger structure is more fragile, and
> the stresses will be higher despite it being lighter than air, but it
> isn't quite intuitive that that is true.
> Fragility would also be a serious factor in every day use. There will
> inevitably be punctures, and it's unlikely you're going to send it back
> into space just for repairs. There's really no avoiding on-planet
> construction.
kilometer across you could plate it in ten-centimeter steel; the total
density will still be lighter than helium.
Note also that punctures don't matter much. It's a foam of carbon
nanotubes. At most you'll lose the lift from whatever material you gouge
out of it, although that wound will then be vulnerable to further damage
until you bolt more steel over it.
Greg Goss
Apr 3, 2013, 1:48:06 AM4/3/13
to
>Fragility would also be a serious factor in every day use. There will
>inevitably be punctures, and it's unlikely you're going to send it back
>into space just for repairs. There's really no avoiding on-planet
>construction.
With readily-available vacuum, you can use micro-pressure to generate
>inevitably be punctures, and it's unlikely you're going to send it back
>into space just for repairs. There's really no avoiding on-planet
>construction.
CLOSED-CELL foams. So are you building a container for the vacuum, or
a substance that IS the container.
If a puncture takes out an ounce or two of your lift, do you even
notice? Or does the lift gracefully degrade over a period of years?
I'm not commenting on the rest of the proposal, but just this bit.
Doc O'Leary
Apr 3, 2013, 11:55:23 AM4/3/13
to
In article <kjg1hm$fbo$1...@reader1.panix.com>,
balloon. It would take some incredible logistics to manage the
construction you describe, never mind the *use* of such a beast. In the
end, if it's not worth the troubles, it won't be built (commercially, at
least).
> Note also that punctures don't matter much. It's a foam of carbon
> nanotubes. At most you'll lose the lift from whatever material you gouge
> out of it, although that wound will then be vulnerable to further damage
> until you bolt more steel over it.
It's easy to handwave the problems away when we're dealing with fiction,
but the reality might be quite different. Weathering, even in small
amounts, may rapidly degrade the foam if it is fragile enough. What
might a lightning strike do to such a craft even without the hull being
breached?
So while it's a nice, steampunk-ish, grand idea, I'm going to wait until
we have something that looks workable on a smaller scale before I get
under a 1km steel structure waiting to pancake. Or on top of it. Or,
really, anywhere near it.
Remus Shepherd <re...@panix.com> wrote:
> We're talking about a structure of arbitrary size. If it's a sphere one
> kilometer across you could plate it in ten-centimeter steel; the total
> density will still be lighter than helium.
Arbitrary doesn't mean practical. I'm reminded of the MythBuster's lead
> We're talking about a structure of arbitrary size. If it's a sphere one
> kilometer across you could plate it in ten-centimeter steel; the total
> density will still be lighter than helium.
balloon. It would take some incredible logistics to manage the
construction you describe, never mind the *use* of such a beast. In the
end, if it's not worth the troubles, it won't be built (commercially, at
least).
> Note also that punctures don't matter much. It's a foam of carbon
> nanotubes. At most you'll lose the lift from whatever material you gouge
> out of it, although that wound will then be vulnerable to further damage
> until you bolt more steel over it.
but the reality might be quite different. Weathering, even in small
amounts, may rapidly degrade the foam if it is fragile enough. What
might a lightning strike do to such a craft even without the hull being
breached?
So while it's a nice, steampunk-ish, grand idea, I'm going to wait until
we have something that looks workable on a smaller scale before I get
under a 1km steel structure waiting to pancake. Or on top of it. Or,
really, anywhere near it.
Wayne Throop
Apr 3, 2013, 1:03:52 PM4/3/13
to
:: Remus Shepherd <re...@panix.com>
:: Note also that punctures don't matter much. It's a foam of carbon
: It's easy to handwave the problems away when we're dealing with
such structures of arbitrary size. I suspect you can't get away from
square-cube problems that easily, and in any event, the interior isn't
floating on air, each bit of interior is having more and more for placed
upon it by scaling up the size (making the amount of material above it
larger; that goes as cube), which it can only distribute over it's area
(which goes up as the square).
Bottom line, I doubt such structures can be made arbitrarily large;
there'd be problems much before tidal forces became a factor...
probably before you get to kilometer sizes.
: So while it's a nice, steampunk-ish, grand idea, I'm going to wait
buckysphere, wrap it in saran wrap, heat the air inside modestly (venting
excess), and you get enough lift to loft an arcology you put inside.
I'm not sure where I read about that one. One of Forward's essays maybe,
or maybe even soembody like Freeman Dyson.
Anyhoo... I'll wait for other folks to live there first.
(Though I do think, in the steampunk (or as they prefer, "gaslight")
genre, it would have been nifty if that's how Baron Wulfenbach implemented
Castle Wulfenbach (first introduced in Agatha Heterodyne and the Airship
City). In fact, it'd be even more steampunky-looking than arbitrary
foam shapes, or even airships. But I suppose it'd be too anachronistic
or something.)
"It's absolutely stupid that we live without an ozone layer.
We have men, we've got rockets, we've got saran wrap - fix it!"
--- Lewis Black
:: Note also that punctures don't matter much. It's a foam of carbon
:: nanotubes. At most you'll lose the lift from whatever material you
:: gouge out of it, although that wound will then be vulnerable to
:: further damage until you bolt more steel over it.
: Doc O'Leary <drolear...@2q2013.subsume.com>
:: gouge out of it, although that wound will then be vulnerable to
:: further damage until you bolt more steel over it.
: It's easy to handwave the problems away when we're dealing with
: fiction, but the reality might be quite different. Weathering, even
: in small amounts, may rapidly degrade the foam if it is fragile
: enough. What might a lightning strike do to such a craft even without
: the hull being breached?
Somewhere upthread, I vaguely recall somebody saying th at you can make
: in small amounts, may rapidly degrade the foam if it is fragile
: enough. What might a lightning strike do to such a craft even without
: the hull being breached?
such structures of arbitrary size. I suspect you can't get away from
square-cube problems that easily, and in any event, the interior isn't
floating on air, each bit of interior is having more and more for placed
upon it by scaling up the size (making the amount of material above it
larger; that goes as cube), which it can only distribute over it's area
(which goes up as the square).
Bottom line, I doubt such structures can be made arbitrarily large;
there'd be problems much before tidal forces became a factor...
probably before you get to kilometer sizes.
: So while it's a nice, steampunk-ish, grand idea, I'm going to wait
: until we have something that looks workable on a smaller scale before
: I get under a 1km steel structure waiting to pancake. Or on top of
: it. Or, really, anywhere near it.
Well, there's always the old "floating arcology" trick. You build a
: I get under a 1km steel structure waiting to pancake. Or on top of
: it. Or, really, anywhere near it.
buckysphere, wrap it in saran wrap, heat the air inside modestly (venting
excess), and you get enough lift to loft an arcology you put inside.
I'm not sure where I read about that one. One of Forward's essays maybe,
or maybe even soembody like Freeman Dyson.
Anyhoo... I'll wait for other folks to live there first.
(Though I do think, in the steampunk (or as they prefer, "gaslight")
genre, it would have been nifty if that's how Baron Wulfenbach implemented
Castle Wulfenbach (first introduced in Agatha Heterodyne and the Airship
City). In fact, it'd be even more steampunky-looking than arbitrary
foam shapes, or even airships. But I suppose it'd be too anachronistic
or something.)
"It's absolutely stupid that we live without an ozone layer.
We have men, we've got rockets, we've got saran wrap - fix it!"
--- Lewis Black
eripe
Apr 5, 2013, 11:06:37 PM4/5/13
to
On Wednesday, April 3, 2013 10:55:23 PM UTC+7, Doc O'Leary wrote:
> In article <kjg1hm$fbo$1...@reader1.panix.com>,
>
> Remus Shepherd <re...@panix.com> wrote:
>
>
>
> > We're talking about a structure of arbitrary size. If it's a sphere one
>
> > kilometer across you could plate it in ten-centimeter steel; the total
>
> > density will still be lighter than helium.
>
>
>
> Arbitrary doesn't mean practical. I'm reminded of the MythBuster's lead
>
> balloon. It would take some incredible logistics to manage the
>
> construction you describe, never mind the *use* of such a beast. In the
>
> end, if it's not worth the troubles, it won't be built (commercially, at
>
> least).
I think that accelerating all that material to orbital speed is too expensive yes, but it is possible to create vacuum on earth too. You would then get a block of foam out as big as your mould and then you can stack these up to your levitating house/city/Enterprise D.
> In article <kjg1hm$fbo$1...@reader1.panix.com>,
>
> Remus Shepherd <re...@panix.com> wrote:
>
>
>
> > We're talking about a structure of arbitrary size. If it's a sphere one
>
> > kilometer across you could plate it in ten-centimeter steel; the total
>
> > density will still be lighter than helium.
>
>
>
> Arbitrary doesn't mean practical. I'm reminded of the MythBuster's lead
>
> balloon. It would take some incredible logistics to manage the
>
> construction you describe, never mind the *use* of such a beast. In the
>
> end, if it's not worth the troubles, it won't be built (commercially, at
>
> least).
If those bricks are easy to make, it will be the cheapest way ever to get airborne!
(If I had as much steel in orbit as to cover a 1km sphere I would strap some rockets on that baby and go to Venus-Sun LaGrane point, shave it off in 0,01 mm thickness to make a sun shade, let Venus cool and start building houses)
>
> > Note also that punctures don't matter much. It's a foam of carbon
>
> > nanotubes. At most you'll lose the lift from whatever material you gouge
>
> > out of it, although that wound will then be vulnerable to further damage
>
> > until you bolt more steel over it.
But closed cell has passive safety, which is good... Just need to include some chambers for lift control.
Not sure how you will create a closed cell with nanotubes tho - but maybe graphene sheets, separated by nanotubes of large diameter would work. (take a strip of graphene and bend it around to make a short tube)
Once you have stack of spaced out sheets, you can close the top, bottom and sides to make a cube. Not sure how big those cubes can be made witout stuff ratling around inside...
>
>
>
> It's easy to handwave the problems away when we're dealing with fiction,
>
> but the reality might be quite different. Weathering, even in small
>
> amounts, may rapidly degrade the foam if it is fragile enough. What
>
> might a lightning strike do to such a craft even without the hull being
>
> breached?
>
>
>
> So while it's a nice, steampunk-ish, grand idea, I'm going to wait until
>
> we have something that looks workable on a smaller scale before I get
>
> under a 1km steel structure waiting to pancake. Or on top of it. Or,
>
> really, anywhere near it.
Doc O'Leary
Apr 6, 2013, 12:11:19 PM4/6/13
to
In article <2bc87152-a11a-476c...@googlegroups.com>,
underestimating how vulnerable exotic materials are to not-so-exotic
events. A lightning strike isn't merely a "coat of paint" nuisance.
> > So while it's a nice, steampunk-ish, grand idea, I'm going to wait until
> >
> > we have something that looks workable on a smaller scale before I get
> >
> > under a 1km steel structure waiting to pancake. Or on top of it. Or,
> >
> > really, anywhere near it.
>
> Well today we have 0,1 steel structures whizzing about everywhere at 900
> km/hour, sometimes the fall down. The giant ball above would fall very slowly
> - you be able to grab your hat and walk away (walk uphill - not downhill :) )
So you naively assume. I, on the other hand, have seen foams rapidly
degrade/melt in the presence of some agent/catalyst that undermines its
structure. If that happens in your vacuum-sealed container, it could
quite quickly turn into something that is just a big metal plate that
gravity is all too happy to drop straight onto your head.
Like I said, I'll need to see something that works on a smaller scale to
be convinced. We didn't start flying with big jet planes, you know.
eripe <erip...@gmail.com> wrote:
> On Wednesday, April 3, 2013 10:55:23 PM UTC+7, Doc O'Leary wrote:
> >
> > It's easy to handwave the problems away when we're dealing with fiction,
> >
> > but the reality might be quite different. Weathering, even in small
> >
> > amounts, may rapidly degrade the foam if it is fragile enough. What
> >
> > might a lightning strike do to such a craft even without the hull being
> >
> > breached?
> >
> A nice coat of paint - problem solved. A steel ship or a car wont last long
> without surface protection either.
Again, that's a nice handwave away of the issues, but I think you're
> On Wednesday, April 3, 2013 10:55:23 PM UTC+7, Doc O'Leary wrote:
> >
> > It's easy to handwave the problems away when we're dealing with fiction,
> >
> > but the reality might be quite different. Weathering, even in small
> >
> > amounts, may rapidly degrade the foam if it is fragile enough. What
> >
> > might a lightning strike do to such a craft even without the hull being
> >
> > breached?
> >
> A nice coat of paint - problem solved. A steel ship or a car wont last long
> without surface protection either.
underestimating how vulnerable exotic materials are to not-so-exotic
events. A lightning strike isn't merely a "coat of paint" nuisance.
> > So while it's a nice, steampunk-ish, grand idea, I'm going to wait until
> >
> > we have something that looks workable on a smaller scale before I get
> >
> > under a 1km steel structure waiting to pancake. Or on top of it. Or,
> >
> > really, anywhere near it.
>
> Well today we have 0,1 steel structures whizzing about everywhere at 900
> km/hour, sometimes the fall down. The giant ball above would fall very slowly
> - you be able to grab your hat and walk away (walk uphill - not downhill :) )
degrade/melt in the presence of some agent/catalyst that undermines its
structure. If that happens in your vacuum-sealed container, it could
quite quickly turn into something that is just a big metal plate that
gravity is all too happy to drop straight onto your head.
Like I said, I'll need to see something that works on a smaller scale to
be convinced. We didn't start flying with big jet planes, you know.
eripe
Apr 12, 2013, 11:38:32 PM4/12/13
to
> I think you're
>
> underestimating how vulnerable exotic materials are to not-so-exotic
>
> events. A lightning strike isn't merely a "coat of paint" nuisance.
Well, any air vehicle or even large structure have the same problems... Lightning strike, windshear, sheet ice, snow buildup, waterfalls over the side, bird/plane/building impacts. There are many things to be anticipated in the design.
>
> underestimating how vulnerable exotic materials are to not-so-exotic
>
> events. A lightning strike isn't merely a "coat of paint" nuisance.
I, on the other hand, have seen foams rapidly
>
> degrade/melt in the presence of some agent/catalyst that undermines its
>
All I am saying is that a foam structure is much easier to build, can be built in any shape, and is stronger and safer than a gas boat, or a plane.
And yes. Dont build a full zise star destroyer replica first. Start with one that is 1 meter long and can zoom around your livingroom, then go from there.
Mark Zenier
Apr 14, 2013, 10:25:41 PM4/14/13
to
In article <kid14f$2if$1...@dont-email.me>,
Wasn't it Thomas Gold who claimed that some methane was non-biological,
ie. it comes from the primordial collection of planetoids that formed
the Earth. (Buzzwords: Deep Drilling, Siljan Ring Drilling Project in
Sweden). If so, the same would result in helium deposits, too. So maybe
this is just the residue of a particularly rich lump, or (more likely),
there was a less permeable than usual strata on top of the deposit.
Sea Wasp (Ryk E. Spoor) <sea...@sgeinc.invalid.com> wrote:
>On 3/20/13 2:44 PM, John F. Eldredge wrote:
>
>> Once this particular helium supply is exhausted, the choice will be to
>> separate it out from natural gas supplies elsewhere (more expensive,
>> since it is at lower concentration elsewhere), or to separate it out from
>> the atmosphere (even more expensive, as helium has the lowest boiling
>> point of any element).
>>
>
> Why is it that that particular field has a lot of helium in it and
>others don't? Does anyone know? My first reaction would be that it would
>indicate a HELL of a lot of radium, or some other alpha emitter, right
>inside or below the gas field.
(Oops. Forgot to check back on this thread).
>On 3/20/13 2:44 PM, John F. Eldredge wrote:
>
>> Once this particular helium supply is exhausted, the choice will be to
>> separate it out from natural gas supplies elsewhere (more expensive,
>> since it is at lower concentration elsewhere), or to separate it out from
>> the atmosphere (even more expensive, as helium has the lowest boiling
>> point of any element).
>>
>
> Why is it that that particular field has a lot of helium in it and
>others don't? Does anyone know? My first reaction would be that it would
>indicate a HELL of a lot of radium, or some other alpha emitter, right
>inside or below the gas field.
Wasn't it Thomas Gold who claimed that some methane was non-biological,
ie. it comes from the primordial collection of planetoids that formed
the Earth. (Buzzwords: Deep Drilling, Siljan Ring Drilling Project in
Sweden). If so, the same would result in helium deposits, too. So maybe
this is just the residue of a particularly rich lump, or (more likely),
there was a less permeable than usual strata on top of the deposit.
Martha Adams
Aug 1, 2013, 10:59:21 PM8/1/13
to
On 4/3/2013 1:48 AM, Greg Goss wrote:
> Doc O'Leary <drolear...@1q2013.subsume.com> wrote:
>
>> Fragility would also be a serious factor in every day use. There will
>> inevitably be punctures, and it's unlikely you're going to send it back
>> into space just for repairs. There's really no avoiding on-planet
>> construction.
>
> With readily-available vacuum, you can use micro-pressure to generate
> CLOSED-CELL foams. So are you building a container for the vacuum, or
> a substance that IS the container.
>
> If a puncture takes out an ounce or two of your lift, do you even
> notice? Or does the lift gracefully degrade over a period of years?
>
> I'm not commenting on the rest of the proposal, but just this bit.
=====================================================================
> Doc O'Leary <drolear...@1q2013.subsume.com> wrote:
>
>> Fragility would also be a serious factor in every day use. There will
>> inevitably be punctures, and it's unlikely you're going to send it back
>> into space just for repairs. There's really no avoiding on-planet
>> construction.
>
> With readily-available vacuum, you can use micro-pressure to generate
> CLOSED-CELL foams. So are you building a container for the vacuum, or
> a substance that IS the container.
>
> If a puncture takes out an ounce or two of your lift, do you even
> notice? Or does the lift gracefully degrade over a period of years?
>
> I'm not commenting on the rest of the proposal, but just this bit.
This interesting discussion doesn't reach out to the most interesting
possibility of using this tech to build a city floating in Venus'
atmosphere. I think I recall a story based on this idea, a few years
back in F&SF Mag. Is the floating city in Venus atmosphere, a
possibility? What would its economics be, to thrive there?
Titeotawki -- Martha Adams [Thr 2013 Aug 01]
Alie...@gmail.com
Aug 2, 2013, 5:56:18 AM8/2/13
to
Know of any planets that need xenoforming by sulfur-philes, and/or warming up in a hurry?
Wait, a quick Google shows that deuterium is more abundant on Venus than anywhere else in Sol system, so that could be a salable export.
Mark L. Fergerson
Martha Adams
Aug 2, 2013, 7:29:41 AM8/2/13
to
Hi, Mark. Yes, maybe deuterium. A research station, probably. Seems
to me, to build such a floating city, you'd want to start with a very
large truss structure suspended from several lighter-than-air balloons
like those so interestingly discussed up this thread. I think several
balloons above, because one or two balloons means too much hanging on
too few (do pass over the pun, this is very serious business). So if
you have the large truss you can distribute the responsibility for lift
over several resources. I don't think the fictional "floating city"
offers just the right image.
I wonder if you might assemble the basic structure in space, maybe even
in Terra not Venus orbit; then drop it down?
OK on the sulphurous atmosphere. But if they are manufacturing
sulphuric acid for export, how do you get it up to space? My thinking
is, that calls for another major technical challenge: a space elevator.
Which in turn, limits the floating city to an equatorial placement.
Titeotwawki -- Martha Adams [Fri 2013 Aug 02]
Greg Goss
Aug 2, 2013, 2:57:21 PM8/2/13
to
Martha Adams <mh...@verizon.net> wrote:
>>>> With readily-available vacuum, you can use micro-pressure to generate
>>>> CLOSED-CELL foams. So are you building a container for the vacuum, or
>>>> a substance that IS the container.
>>>> With readily-available vacuum, you can use micro-pressure to generate
>>>> CLOSED-CELL foams. So are you building a container for the vacuum, or
>>>> a substance that IS the container.
>>> This interesting discussion doesn't reach out to the most interesting
>>> possibility of using this tech to build a city floating in Venus'
>>> atmosphere. I think I recall a story based on this idea, a few years
>>> back in F&SF Mag. Is the floating city in Venus atmosphere, a
>>> possibility? What would its economics be, to thrive there?
>>> possibility of using this tech to build a city floating in Venus'
>>> atmosphere. I think I recall a story based on this idea, a few years
>>> back in F&SF Mag. Is the floating city in Venus atmosphere, a
>>> possibility? What would its economics be, to thrive there?
>sulphuric acid for export, how do you get it up to space? My thinking
>is, that calls for another major technical challenge: a space elevator.
> Which in turn, limits the floating city to an equatorial placement.
If you're building it onto a space elevator, you're wasting the
>is, that calls for another major technical challenge: a space elevator.
> Which in turn, limits the floating city to an equatorial placement.
balloons (or structural aeroless aerogel) . Just hang the whole thing
from your skyhook.
--
We are geeks. Resistance is voltage over current.
Wayne Throop
Aug 2, 2013, 3:26:44 PM8/2/13
to
:: sulphuric acid for export, how do you get it up to space? My
: If you're building it onto a space elevator, you're wasting the
synchronous but wouldn't a space elevator require prohibitively high
relative velocities between city and (corrosive) atmosphere?
Possibly, juxtaposition of "space elevator" and "skyhook" is confusing me.
The two are distinct in important ways. I'll assume a "space elevator"
is a spin-and-orbit synchronized skyhook, normally oriented tidewise.
So anyways... leave the city low-velocity wrt the atmosphere, and use
buoyancy. Have a skyhook be able to periodically lift payloads from
the city (how you reboost it's orbit is another issue, but there are
many ways). So, no space elevator, and no hanging anything from the
skyhook (permanently).
And the skyhook isn't limited to equatorial placement (though it does
make things more complicated and gives you lots of "windows" issues
for lifts and such.
:: thinking is, that calls for another major technical challenge: a
:: space elevator.
:: Which in turn, limits the floating city to an equatorial placement.
: Greg Goss <go...@gossg.org>
:: space elevator.
:: Which in turn, limits the floating city to an equatorial placement.
: If you're building it onto a space elevator, you're wasting the
: balloons (or structural aeroless aerogel) . Just hang the whole thing
: from your skyhook.
On *venus*? Doesn't the... hm... OK, so it doesn't have to be ground
: from your skyhook.
synchronous but wouldn't a space elevator require prohibitively high
relative velocities between city and (corrosive) atmosphere?
Possibly, juxtaposition of "space elevator" and "skyhook" is confusing me.
The two are distinct in important ways. I'll assume a "space elevator"
is a spin-and-orbit synchronized skyhook, normally oriented tidewise.
So anyways... leave the city low-velocity wrt the atmosphere, and use
buoyancy. Have a skyhook be able to periodically lift payloads from
the city (how you reboost it's orbit is another issue, but there are
many ways). So, no space elevator, and no hanging anything from the
skyhook (permanently).
And the skyhook isn't limited to equatorial placement (though it does
make things more complicated and gives you lots of "windows" issues
for lifts and such.
Martha Adams
Aug 3, 2013, 4:52:19 AM8/3/13
to
Hi, Greg. I suspect you aren't serious so why do you say this? If we
are somewhere near a context of what current or near-future tech can do?
Because, you seem to be saying that you'd hang a thousand tons or so off
the skyhook, but today, we can't even build a space elevator that can
hoist one single ton up to orbit. Yes, Venus gravity is less than Terra
gravity, but, *that much*? ??
When I write here I'm posting from a pov that we should be trying to get
to where we'd be if Apollo hadn't been killed to "save" money for
Vietnam (then) and for more wars since. I'm imagining we can get all
the politicians out of space work -- politicians make real bad
engineers. So I want to think not in blue-sky terms but not too
limited, for instance, I'd have said the flying crane to land a rover on
Mars, was too far out. But it wasn't: it worked. So "too far out"
isn't well defined, but I think your idea to hang a Venus city from a
skyhook / space elevator is in these days, too much.
Titeotwawki -- Martha Adams [Sat 2013 Aug 03]
Martha Adams
Aug 3, 2013, 5:01:40 AM8/3/13
to
Hi, Wayne. You've got a point there. I was thinking in terms of the
space elevator project here on Terra that would have had two or three
converted surplus oil tankers under a platform floating in the ocean
west of South America. Which ocean is nearly stationary; but the jet
stream overhead can be blowing 200 mph. (Jupiter's rings and that great
Spot there, also come to mind.) So I was wrong to not think, well, *how
fast* is the air over Venus' equator moving, at City level?
You can't have the City moving in the atmosphere, because that will
require energy to keep it moving.
Alie...@gmail.com
Aug 3, 2013, 11:03:10 PM8/3/13
to
http://en.wikipedia.org/wiki/File:Venusatmosphere.svg
wind speeds are about the same as at the cloud tops:
http://ase.tufts.edu/cosmos/view_picture.asp?id=1103
though recently they've sped up inexplicably:
http://www.astronomy.com/~/link.aspx?_id=f85066e3-4581-4de3-a39f-057cc0559ea2
to nearly 250mph relative to the surface.
> You can't have the City moving in the atmosphere, because that will
> require energy to keep it moving.
http://www.frc.ri.cmu.edu/~hpm/project.archive/1976.skyhook/papers/scasci.txt
I suppose he didn't know about buckminsterfullerenes.
Mark L. Fergerson
James Nicoll
Aug 4, 2013, 10:03:22 AM8/4/13
to
In article <VJednbMqJc97W2HM...@giganews.com>,
A space elevator from the surface to synchroneous orbit like the one
in FOUNTAINS OF PARADISE isn't really an option on Venus. Venus rotates
slowly and the elevator would be unmanagably long.
>You can't have the City moving in the atmosphere, because that will
>require energy to keep it moving.
The jet stream is moving at 300-400 km/h; that should move a floating city up
at the 50 km level (where temperatures are Earthlike) nicely.
--
http://www.livejournal.com/users/james_nicoll
http://www.cafepress.com/jdnicoll (For all your "The problem with
defending the English language [...]" T-shirt, cup and tote-bag needs)
in FOUNTAINS OF PARADISE isn't really an option on Venus. Venus rotates
slowly and the elevator would be unmanagably long.
>You can't have the City moving in the atmosphere, because that will
>require energy to keep it moving.
at the 50 km level (where temperatures are Earthlike) nicely.
--
http://www.livejournal.com/users/james_nicoll
http://www.cafepress.com/jdnicoll (For all your "The problem with
defending the English language [...]" T-shirt, cup and tote-bag needs)
Wayne Throop
Aug 4, 2013, 12:54:27 PM8/4/13
to
: jdni...@panix.com (James Nicoll)
: A space elevator from the surface to synchroneous orbit like the one
be anchored to the ground (just hang a plumb bob from it or whatnot).
It could just be a synchronous skyhook, and have any orbit period
you like.
You loose the free momentum transfer, and the air is *really* rushing
past the cable end, and you have problems keeping it boosted... but it's
doable, seems to me.
: The jet stream is moving at 300-400 km/h; that should move a floating
skyhook anchored to the city. 4e5 m/h should make the oribtal period
much better than one anchored to the surface. And... I suppose it also
gives you your free reboost; the coupling between the anchor and the
atmosphere is just a bit more... mushy than than between an anchor
and the ground. And you could hang out sails. Cool; wind-powered
space elevators!
Assuming the wind is dead reliable.
: A space elevator from the surface to synchroneous orbit like the one
: in FOUNTAINS OF PARADISE isn't really an option on Venus. Venus
: rotates slowly and the elevator would be unmanagably long.
Yah, that's what I started to say, until I realized it doesn't have to
: rotates slowly and the elevator would be unmanagably long.
be anchored to the ground (just hang a plumb bob from it or whatnot).
It could just be a synchronous skyhook, and have any orbit period
you like.
You loose the free momentum transfer, and the air is *really* rushing
past the cable end, and you have problems keeping it boosted... but it's
doable, seems to me.
: The jet stream is moving at 300-400 km/h; that should move a floating
: city up at the 50 km level (where temperatures are Earthlike) nicely.
Hm. I'm not sure what that would do to the length of a synchronous
skyhook anchored to the city. 4e5 m/h should make the oribtal period
much better than one anchored to the surface. And... I suppose it also
gives you your free reboost; the coupling between the anchor and the
atmosphere is just a bit more... mushy than than between an anchor
and the ground. And you could hang out sails. Cool; wind-powered
space elevators!
Assuming the wind is dead reliable.
Greg Goss
Aug 4, 2013, 1:29:22 PM8/4/13
to
jdni...@panix.com (James Nicoll) wrote:
>In article <VJednbMqJc97W2HM...@giganews.com>,
>Martha Adams <mh...@verizon.net> wrote:
>>On 8/2/2013 3:26 PM, Wayne Throop wrote:
>>> :: sulphuric acid for export, how do you get it up to space? My
>>> :: thinking is, that calls for another major technical challenge: a
>>> :: space elevator.
>>> :: Which in turn, limits the floating city to an equatorial placement.
>>>
>>> : Greg Goss <go...@gossg.org>
>>> : If you're building it onto a space elevator, you're wasting the
>>> : balloons (or structural aeroless aerogel) . Just hang the whole thing
>>> : from your skyhook.
>>>
>>> On *venus*? Doesn't the... hm... OK, so it doesn't have to be ground
>>> synchronous but wouldn't a space elevator require prohibitively high
>>> relative velocities between city and (corrosive) atmosphere?
>>>
>>> Possibly, juxtaposition of "space elevator" and "skyhook" is confusing me.
>>> The two are distinct in important ways. I'll assume a "space elevator"
>>> is a spin-and-orbit synchronized skyhook, normally oriented tidewise.
>In article <VJednbMqJc97W2HM...@giganews.com>,
>Martha Adams <mh...@verizon.net> wrote:
>>On 8/2/2013 3:26 PM, Wayne Throop wrote:
>>> :: sulphuric acid for export, how do you get it up to space? My
>>> :: thinking is, that calls for another major technical challenge: a
>>> :: space elevator.
>>> :: Which in turn, limits the floating city to an equatorial placement.
>>>
>>> : Greg Goss <go...@gossg.org>
>>> : If you're building it onto a space elevator, you're wasting the
>>> : balloons (or structural aeroless aerogel) . Just hang the whole thing
>>> : from your skyhook.
>>>
>>> On *venus*? Doesn't the... hm... OK, so it doesn't have to be ground
>>> synchronous but wouldn't a space elevator require prohibitively high
>>> relative velocities between city and (corrosive) atmosphere?
>>>
>>> Possibly, juxtaposition of "space elevator" and "skyhook" is confusing me.
>>> The two are distinct in important ways. I'll assume a "space elevator"
>>> is a spin-and-orbit synchronized skyhook, normally oriented tidewise.
>A space elevator from the surface to synchroneous orbit like the one
>in FOUNTAINS OF PARADISE isn't really an option on Venus. Venus rotates
>slowly and the elevator would be unmanagably long.
Neither I, nor the guys who criticised my comment, thought the
>in FOUNTAINS OF PARADISE isn't really an option on Venus. Venus rotates
>slowly and the elevator would be unmanagably long.
"skyhook" idea through properly.
Or at least he didn't express it properly to make me aware of the
problem.
eripe
Aug 4, 2013, 10:43:30 PM8/4/13
to
On Sunday, August 4, 2013 11:54:27 PM UTC+7, Wayne Throop wrote:
> : (James Nicoll)
BTW just saw this.
http://en.wikipedia.org/wiki/Terraforming_of_Venus
Seems like floating cities is a nice platform for building sunshade balloons and converting the CO2 atmosphere.
2CO2 + 2H2 -> 2H20 + O2 + 2C
Just add hydrogen.
I wonder how difficult it would be to convert CO2 -> 14H2
> : (James Nicoll)
>
>
> and the ground. And you could hang out sails. Cool; wind-powered
>
> space elevators!
>
>
> Assuming the wind is dead reliable.
Another way is to use propellars or jet engines mounted on the part of the skyhook that dips into the atmosphere. Then you could actively control the resulting forces. (Dont sway to either side and give a boost)
>
> and the ground. And you could hang out sails. Cool; wind-powered
>
> space elevators!
>
>
> Assuming the wind is dead reliable.
BTW just saw this.
http://en.wikipedia.org/wiki/Terraforming_of_Venus
Seems like floating cities is a nice platform for building sunshade balloons and converting the CO2 atmosphere.
2CO2 + 2H2 -> 2H20 + O2 + 2C
Just add hydrogen.
I wonder how difficult it would be to convert CO2 -> 14H2
John Meacham
Feb 27, 2014, 11:58:18 PM2/27/14
to
If you are willing to go arbitrarily large, you could use nitrogen as a lifting gas. There are aerogels that actually float in the air when impregnated with nitrogen. It is about 3% lighter than air. If you have a closed air supply for the city, the breathing air can actually be a lifting gas, just make it signifigantly warmer than ambient, which you may want to do for comfort anyway. Would be good practice for venus. You could even mix in helium or neon to some level and improve the odds without hurting the breathability.
I too was thinking of a closed cell foam created in vacuum but then wasn't sure what you would use as a foaming agent, as those are usually gasses to create the cells in the first place. maybe steam which then condenses to water once the foam has been made? or make it hydrogen permeable, use hydrogen as the foaming agent and let it sit in vacuum for a while til it all diffuses out.
I too was thinking of a closed cell foam created in vacuum but then wasn't sure what you would use as a foaming agent, as those are usually gasses to create the cells in the first place. maybe steam which then condenses to water once the foam has been made? or make it hydrogen permeable, use hydrogen as the foaming agent and let it sit in vacuum for a while til it all diffuses out.
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