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Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Inflatable towers in Venus

Also remember half of the Sun's disk would be below the horizon at all times as the disk of the Sun slowly moves eastward along the horizon, it might even be cooler at the 55 km altitude at 1 atmosphere of pressure. I think the Sun would appear rather red as it does along our horizon. If the balloon is not tethered, it could use propellers to move away from the Sun, and thus make it appear to set, so there could be night, then it would turn around and head back towards the Sun for a Sunrise, that way we could have a normal 24-hour diurnal cycle. Maybe that's worth considering.

Doesn't say how fast these things move. I wonder how fast this airship would have to move to get the entire disk of the Sun below the horizon?

These folks may have to be couch potatoes. I wonder if they could have exercise equipment behind those chairs. I think a treadmill would be nice, they'd need a lavatory, and maybe a small kitchen in the back. Also when they flushed the toilet, where do you suppose the water would go? Probably get recycled I imagine, if the equipment to do that wasn't too heavy. The engines that propel the airship would be electrical, they would probably hear a whirr sort of like a giant fan. Do you think there would be handholds along the sides of the airships so astronauts can climb to the top of the gas bag in protective suits? If the airship climbs high enough, they can get a good view of the stars at night, as there never is a Moon to drown them out. Maybe they can set up a telescope on the top and look at the Earth.

Terraformer

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From: Ceres

Registered: 2007-08-27

Posts: 3,817

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Re: Inflatable towers in Venus

What? There's plenty of room within the envelope, you just have to use Nitrox instead of Helium.

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"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony

Tom Kalbfus

Banned

Registered: 2006-08-16

Posts: 4,401

Re: Inflatable towers in Venus

What? There's plenty of room within the envelope, you just have to use Nitrox instead of Helium.

Well instead of having volume limits you have weight limits as nitrogen and oxygen don't produce as much lift as Helium and hydrogen. You would have to have a lot of empty space with nothing but air inside and only a tiny portion of the interior volume could have something besides air in it. I think if you tethered a Hydrogen balloon to the air balloon, you could put more stuff in the air balloon. Another thing you could do is anchor it to the ground, and use the airflow around it to generate even more lift. The anchor cables would have to be 55+ km long, anchoring it to the top of Maxwell Montes might give you another 10 km and thus cooler atmosphere around it. So what would the air pressure and temperature be at 65 km? I think less than a Third of a bar of atmospheric pressure, judging from Mount Everest on Earth, which is about 8 km above sea level.

Void

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Registered: 2011-12-29

Posts: 7,093

Re: Inflatable towers in Venus

Just on the side,

I think if you did have a Hydrogen balloon, and imposed a minus electrical charge inside of it, and a relative plus electrical charge outside of it, you might be able to encourage wayward Hydrogen atoms trying to escape through the pores to stay inside that balloon envelope.

Obviously you would not want such a charge magnitude that it would burn holes in the balloon.

This device would also serve as a capacitor, for what that is worth.  Not a very strong one however.

If it were me, I would consider an envelope containing N2 or HE, and inside of that multiple Hydrogen envelopes.

I am sure that for Venus, every trick in the book will have some use at some time for some purpose, as far as lighter than "Air" methods go.

Last edited by Void (2015-08-26 16:50:19)

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Done.

Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Inflatable towers in Venus

I think the hydrogen envelope should not be inside a breathable air envelope because leaked hydrogen can burn in that atmosphere and we're back to the Hindenburg problem. the hydrogen balloons should be separate and surrounded by atmosphere they can't burn in. Nitrogen and Oxygen has its own lifting power, hydrogen balloons simply supplement it. I think the top of the cloud layer would be the best place to locate a floating city.

here is an altitude vs temperature plot. As you can see from the chart the temperature at the cloud tops is around -13 degrees centigrade, and would probably be even colder at the South Pole, the altitude is 58 km.

Here is an altitude vs pressure plot. the chart indicates that at the level of 60 km we have a pressure of 200 mbars, so about one fifth the pressure of the air on Earth. The Earth's atmosphere is one fifth oxygen, so we could breath that air if it were 100% oxygen, this is also an air pressure of 2 tons per square meter both inside and outside the balloon, 100 mbars of nitrogen plus trace amounts of carbon-dioxide and water vapor and we can grow plants inside, the outward pressure would thus be 1 ton per square meter, any leaks would leak outward. Composition would be 66% oxygen ad 32% nitrogen, the remaining 1% would be carbon-dioxide and water vapor. Since were above the clouds, we'd get direct sunshine 100% of the time. I think the Sun would appear red since it would be on the horizon. We could call this "Twilight City".

We can also see that if we fly below the clouds the air pressure is 2 atmospheres and the temperature is at 350 K or about 73 degrees centigrade.

Last edited by Tom Kalbfus (2015-08-30 21:16:55)

Antius

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From: Cumbria, UK

Registered: 2007-05-22

Posts: 1,003

Re: Inflatable towers in Venus

Hydrogen would be a difficult lifting gas to use on Venus.  In Zeppellins, the gas tended to diffuse out of the envelopes and these had to be refilled and purged at the end of each trip.  That was a non-trivial expense for the Germans, even on a planet with plenty of hydrocarbons and water.  Nitrogen may be the best we can do on Venus.

Antius

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From: Cumbria, UK

Registered: 2007-05-22

Posts: 1,003

Re: Inflatable towers in Venus

I think the hydrogen envelope should not be inside a breathable air envelope because leaked hydrogen can burn in that atmosphere and we're back to the Hindenburg problem. the hydrogen balloons should be separate and surrounded by atmosphere they can't burn in. Nitrogen and Oxygen has its own lifting power, hydrogen balloons simply supplement it. I think the top of the cloud layer would be the best place to locate a floating city.
http://adamant.typepad.com/photos/uncat … enus_2.gif
here is an altitude vs temperature plot. As you can see from the chart the temperature at the cloud tops is around -13 degrees centigrade, and would probably be even colder at the South Pole, the altitude is 58 km.
http://www.astro.wisc.edu/~townsend/res … enus-p.gif
Here is an altitude vs pressure plot. the chart indicates that at the level of 60 km we have a pressure of 200 mbars, so about one fifth the pressure of the air on Earth. The Earth's atmosphere is one fifth oxygen, so we could breath that air if it were 100% oxygen, this is also an air pressure of 2 tons per square meter both inside and outside the balloon, 100 mbars of nitrogen plus trace amounts of carbon-dioxide and water vapor and we can grow plants inside, the outward pressure would thus be 1 ton per square meter, any leaks would leak outward. Composition would be 66% oxygen ad 32% nitrogen, the remaining 1% would be carbon-dioxide and water vapor. Since were above the clouds, we'd get direct sunshine 100% of the time. I think the Sun would appear red since it would be on the horizon. We could call this "Twilight City".

We can also see that if we fly below the clouds the air pressure is 2 atmospheres and the temperature is at 350 K or about 73 degrees centigrade.

73C may be workable as the effective lift at 2bar is double (almost) what it would be at 1bar.  I say almost because the higher temperature means slightly lower air density.  But an air source heat pump may be sufficient to keep habitation spaces cool and at 340K the COP is still reasonable.

Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Inflatable towers in Venus

73C may be workable as the effective lift at 2bar is double (almost) what it would be at 1bar.  I say almost because the higher temperature means slightly lower air density.  But an air source heat pump may be sufficient to keep habitation spaces cool and at 340K the COP is still reasonable.

At that level, the habitat would be able to see the ground below, and there would be a yellow sky above consisting of nearby sulfuric acid clouds. I think at this level, we would still get occasional scalding sulfuric acid rain hitting the surface of the habitat, as it hasn't completely evaporated away at this point. At the higher altitude of around 60 km, the atmospheric pressure would be one fifth of sea level Earth, we would have a blue sky above during the day, and a view of the stars at night. At the poles would would have a perpetual twilight, as the Sun would bob above and below the cloudy horizon due to the slight axial tilt of Venus. When the Sun was half above and half below the horizon, we would get about as much Sunlight as the Polar region of Earth when the Sun is just above the horizon, the Sun at this shallow angle would appear red as the blue light is scattered through this thick atmosphere. It would be nice to get a good optical look at the surface below at the lower level however, as the observation post would supposedly be there to study the planet Venus after all!

Antius

Member

From: Cumbria, UK

Registered: 2007-05-22

Posts: 1,003

Re: Inflatable towers in Venus

73C may be workable as the effective lift at 2bar is double (almost) what it would be at 1bar.  I say almost because the higher temperature means slightly lower air density.  But an air source heat pump may be sufficient to keep habitation spaces cool and at 340K the COP is still reasonable.

At that level, the habitat would be able to see the ground below, and there would be a yellow sky above consisting of nearby sulfuric acid clouds. I think at this level, we would still get occasional scalding sulfuric acid rain hitting the surface of the habitat, as it hasn't completely evaporated away at this point. At the higher altitude of around 60 km, the atmospheric pressure would be one fifth of sea level Earth, we would have a blue sky above during the day, and a view of the stars at night. At the poles would would have a perpetual twilight, as the Sun would bob above and below the cloudy horizon due to the slight axial tilt of Venus. When the Sun was half above and half below the horizon, we would get about as much Sunlight as the Polar region of Earth when the Sun is just above the horizon, the Sun at this shallow angle would appear red as the blue light is scattered through this thick atmosphere. It would be nice to get a good optical look at the surface below at the lower level however, as the observation post would supposedly be there to study the planet Venus after all!

Maybe a good early choice for space tourism.  As all of your resources would need to be brought in from outside, it is a good idea to have a good source of outside revenue as well.  Let's say 1000 rich tourists each paying $100,000 a week?  That's 5.2Bn a year.

SpaceNut

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Registered: 2004-07-22

Posts: 28,866

Re: Inflatable towers in Venus

Why towers are a problem on planets of mars to earth sizing.....