Physics transfers fuel inside carbon nano tube - fuel into space

GCNRevenger · 2004-03-11 15:03:58

Rockets do blow up, but not that often (Delta-II has a 297 for 300 reccord I think), and if they blow up... who cares? If your tube fails, even once, then all that work and expense is for nothing. Rockets like the DC-X or spaceplanes like the X-30 NASP could also accomplish an order of magnetude improvement in the cost per pound.

Also, considering the charge barrier system that protects the tube from interacting with the gas particles, it will actually be as heavy or more than a true space elevator, especially since you have to go up all the way to Geosynchronous orbit to mount the counterweight, and I think that the gas liquification station at 400km will be extremely heavy.

Solar power isn't free... the cost of making & installing the equipment, such as a huge solar farm for the multimegawatt energies needed, spread over the life of the system is just as real an expense as the maintenance and operations. Again, solar power isn't free, or else we'd all be using it...

Second, batteries are not practical to store multimegawatt energies for many hours a day, every day. They are not that efficent, and they would wear out quickly.

Third, you cannot simply shut down the tube whenever is nessesarry, because of the high energies involved in the ionization chaimber and that you can't have alot of free particles inside the tube that may come back down on you.

ERRORIST · 2004-03-11 15:47:10

1% rocket failure is pretty bad especially if people are in them.
How many have gone astray, and had to be destroyed? The space elevator also has a counter weight in Geosynchronous orbit, and it is much more massive. The solar farm doesn't have to be as large as it used to be since the panels are alot more smaller and effiecent today.At any given time there is not that much volume of paticles in the tube.,

SBird · 2004-03-11 20:29:54

Egads, I can't believe that I'm letting myself get dragged into this discussion...

Anyways, ERRORIST, your fuel tube is going to be far more massive than the space elevator. They both have to be the same length. The whole reason that the space elevator is 36,000 miles long with a counterweight at the end is that's what's required for centrifugal force to hold the elevator up. Unless you want your fuel straw to fall down to the ground, it's got to have the exact same arrangement as the space elevator. Furthermore, the space elevator is just a ribbon that has to be strong enough for stuff to climb up. Your design has to be a tube that can carry fuel, and hold up some sort of pumping station. Not to mention the massive amount of weight of the electrostatic shielding, micrometorite protection, etc. Your tube will probably outmass the elevator by at least a factor of 5. Even carbon nanotubes don't have enough strength to work in this situation.

ERRORIST · 2004-03-11 21:17:21

The ion pump is down below at sea level or on land. The weight of it does not have to be supported by the tube. The weight of the ions in the tube at any one time is not that great since it is a ionized gas. The tube diameter is very small.
600Kpa is the theoretical strength for nanotube material. 60kpa is what is projected for the space elevator. We have material now at 120Kpa. BTW the tube could also be built from the ground up to space?????

GCNRevenger · 2004-03-11 23:19:49

Rocket failure rate and crew survival have only become the same figure with the insane Space Shuttle, and its zero crew escape capabilities... Nor do people need to ride the rocket, the DC-X and X-33 were planned to operate unmanned.

The fuel station, the thing that captures the ions and compresses/liquifies the extremely thin gasses in orbit, will have to be supported by the entire length of cable from the 400km up to the 36,000km counterweight, which I imagine will have to be quite strong, especially since the fuel station would be in a artifical orbit.

No, the cable must be dropped from orbit... you don't try to climb a moutain by throwing a rope to the top.

And finally the unavoidable issue, is that this system simply cannot move substantial masses without becoming unreasonably large. This thing would have to be Star Wars proportioned to have any hope of moving more than a single ton of hydrogen a year, a fraction what even a cheap comm sat. launcher can handle.

ERRORIST · 2004-03-12 00:17:24

The fuel station, the thing that captures the ions and compresses/liquifies the extremely thin gasses in orbit, will have to be supported by the entire length of cable from the 400km up to the 36,000km counterweight.

Not exactly, it doesn't have to be attached to the structure?

A carbon nonotube structure can also be built from the ground up. It is well within the tensile strength of the molecule.

Aside from the inital cost of solar panels and maintenance on them power comes pretty darn cheap. Also,a new type of electrical power generation is coming out. Basically the sun warms air over a large area of land, and it flows very fast though a tall stack. Figures show it can produce 200 Mws of power.They say it is a reliable energy source near the equator. Both sources are very cheap.

GCNRevenger · 2004-03-12 00:37:48

Yes it does have to be attached to the structure, because if you look straight down from Geosynchronous orbit were the counterweight must be, which by the way must be very heavy to counter the weight of the fuel station, all orbits directly below GEO that stay alligned with the cable are moving too slowly to maintain orbit, so the cable itself must support most of the weight of the fuel station.

Edit: Oh yes, and even though the CNT material may be strong enough, no known building method can build straight up that far while still keeping the CNT cable/tube straight up. It must be lowerd from orbit.

You understimate the cost of building such a power plant... if the entire system will last for fifty years and haul 10 tons a year of ANY fuel and cost $20 billion to build (a small figure by my estimate) and be FREE to operate, thats still quadruple the cost of launching a Delta-IV HLV rocket every other year with fuel.

Two technical concerns you have not yet addressed...
1: Low flow rate, that even best-case will likly move less than even a ton a year of hydrogen, which is 1/20th of a large rocket's capacity, and still not competitive with rockets for Xenon or other ion fuels.
2: Energy transmission to the cable's beam guide system and liquification plant.

ERRORIST · 2004-03-12 00:59:07

The fuel station can maintain its orbit like the shuttle does.A high volume low velocity ion pump can be built easy. All you need is cheap power to run it, and it comes from solar energy or from that thermal tower.Removable links are very flexable and make good connections. They are very common for comercial generators.

GCNRevenger · 2004-03-12 01:11:33

Even with an ion pump that produces a hundred times that of the biggest ion drive, you are still talking only hundreds of kilograms of hydrogen over the course of months or a year, where a launch or two on a commertial rocket can match or best that without spending a dime on development or construction costs, and with a RLV rocket or true space elevator would blow away even this price... and as mentioned before, there is no good reason to move vast masses of ion engine fuel, since you don't need large masses.

The fuel station can maintain its orbit with a large chemical engine... but the amount of fuel it uses would be astronomical per year, far exceeding the amount of fuel you actually send up the tube.

And "cheap power" I remind you must take into account the construction costs of the generator over the lifespan, which will be quite large, and is not a trivial factor as you insist.

As far as links, I am not talking about the structural requirements for the power lines, I am talking about the resistance to current that several hundred miles of wire poses while it is at high temperatures in full unfilterd sunlight.

GCNRevenger · 2004-03-12 01:16:03

To put some numbers on the table...

Lets say that your ion pump can move ten thousand times the number of moles as your 20g/day Xenon ion engine example... Since hydrogen weighs 1/132nd as much per mole, thats a grand total of 553 kilograms a year. Total. Only half a ton. You could launch this much to GEO using a cheap satelite launcher for under $100M, perhaps less than $50M counting tankage.

ERRORIST · 2004-03-12 01:27:57

Here is an ion pump that may do the job, and it is variable also. I have heard of this before.

[http://www.space.com/businesstechnology … 807-1.html]http://www.space.com/busines....-1.html

GCNRevenger · 2004-03-12 01:35:36

The VASIMR engine? Problem: It uses extremely high temperature plasma, not positivly charged hydrogen nucleii, which the charged tube cann't contain and would immediatly burn through.

ERRORIST · 2004-03-12 01:45:09

Could it be modified?

GCNRevenger · 2004-03-12 01:49:12

The only way would be to string magnetic rings up the whole length of the tube which would require ungodly amounts of power and weigh a terrible mass, and the radiative energy from the plasma would still scorch the tube until it disintigrated.

Answer: No.

ERRORIST · 2004-03-12 01:50:24

I'll figure it out.

GCNRevenger · 2004-03-12 01:56:07

I really think this is a dead end of an idea... there is just no way that this concept - a pipeline to the sky - could possibly be competitive with conventional launch methods taken to the next generation, if even that.

If you haven't noticed, gravity really sucks.

ERRORIST · 2004-03-12 02:03:06

actually space does.

ERRORIST · 2004-03-12 02:14:37

Can anion resin beads give H2 atoms a positive charge?

SBird · 2004-03-12 02:33:18

Using an ionized gas inside a carbon nanotube will not work. The ionization energy of Hydrogen is over 1.3 keV. This is an energy level that is orders of magnitude greater than the C-C bond energy of the carbon atoms in the nanotube. What will happen is your ionized hydrogen will strip electrons off of the carbon atoms and destroy your nanotube. Basically, the ionized hydrogen will burn your nanotubes up. And no, before you ask, there is NO way to prevent this.

FYI, the numbers you are giving arent kPa(kilopascals), those numbers should be GPa(gigapascals). An object within the kilopascal tensile strength range is about as strong as a rubber band. The 600 GPa figure is a purely theoretical one which has little basis in reality. The 120-150 GPa figure comes from measurements of isolated flaw-free single walled nanotubes that whose stiffness was measured by measuring their vibration harmonics. These tubes are difficult to make and have never been made more than a few microns in length. The bulk nanotubes that are used for most fabrication are multi-walled nanotubes that have MUCH lower strength. Furthermore, the cables that have been made are a bunch of nanotubes that are basically glued together. The best figures I've seen for these are in the range of 100 MPa - 6000 times weaker than what is required for a space elevator. There is no such thing as a long carbon nanotube and it is highly unlikely that there ever will be - these cables are basically the equivalent of a bunch o tiny nanotube fiber lint that's been glued together - your hydrogen will be lucky to make it a single millimeter before it just gets stuck in the glue.

Tensile strength is a material's strength in *tension* not compression. A rope has high tensile strength but if you try to push a rope up into the sky, you won't get very far. A nanotube 'rope' would be less floppy than a regular rope but you'd be lucky to get it 20 feet off the ground before it just flopped over.

Additionally, solar cells, although having gotten cheaper in the last few decades are still a very expensive method of energy generation. Even the best solar cells are still twice as expensive as regular fossil fuel power because of the high cost of the panels. Plus, the kinds of power you are talking about would require a solar cell array the size of a city. Remember that at noon at the equator on a cloudless day, you are pulling about 1500 watts/square meter in solar power. The best commercial solar cells only get about 12% efficiency. Therefore, you get about 180 watts per square meter. At current market prices, the solar cells for 100 MW of power are going to cost you over $200 million. Projected improvements over the next decade might bring that number down to $75 million but you get the idea - solar power is by no means free.

I'm familiar with the new solar/wind generation method you mention. The problem is that noone's ever built one of these. Furthermore, the complexity of making a mile high concrete tube is not simple. Don't count on that technology until you actually see a working model.

SBird · 2004-03-12 02:37:27

Anion resin beads cannot give H2 a positive charge. In fact, chemistry tetbooks that show H+ ions are actually incorrect. The free energy of an H+ ion is gargantuan and could never be created by a chemical reaction. H+ in water (as an acid) is always H3O+ or some variant therof. At the most, an ion exchange resin can pull or push electrons with 1eV or less of potential. To ionize hydrogen, you need >1300 eV.

GCNRevenger · 2004-03-12 09:36:01

No no an ion exchange resin only works well with a solvent (water) which the tube won't have, and as Sbird has mentioned the ionization energy to put a charge on Hydrogen is pretty extreme (one reason why it isn't used for ion fuel) and is usually done by in particle accelerator.

The solution to the problem of preventing the ionized hydrogen from eating the tube walls is to generate a positive electric field around the inside of the tube, which in theory would work, but would weigh an ungodly amount and require gobs of power I would think.

And finally, you have to actually get power to the gas liquification station, which will either need very large solar pannels, a nuclear reactor, or somthing to power it.

The possibility of contiguous single-wall CNTs of arbitrary length and near-perfect ordering really depends on nanotechnology I think; the ability to manipulate individual carbon atoms into place could do the job perhaps, but as of now its looking like a 50/50 "maybe" that single atom manipulation is possible.

ERRORIST · 2004-03-12 10:07:33

I think the tube at first may need a large supply of electrical power but once it has the + charge in about 1/10 of second it should remain like a capacitor, and may need topping off from time to time.

GCNRevenger · 2004-03-12 10:24:05

I doubt that very much, especially since your tube will be traveling through the magnetosphere, and you are still talking about creating a powerful electric charge along a several hundred mile length.

Again, electricity supply is only peripherally important, and even if you have all the free electricity you want, the ion pump and liquification station are still limiting factors.

ERRORIST · 2004-03-12 10:34:14

Here is a 2500 watt ion engine. How many watts would one need to do the job of pumping ions up the tube?

[http://science.nasa.gov/newhome/headlin … pr99_2.htm]http://science.nasa.gov/newhome/headlin … pr99_2.htm

GCNRevenger · 2004-03-12 10:44:05

A little comparison shopping time... remember that 20g/day Xenon ion thruster? Lets see how much you would have to scale it up to make it competitive with a hypothetical cargo systems yearly on a mole-equivilent basis...

DC-Y SSTO RLV reuseable cargo rocket: 7,200kg of LH2 with 20% tankage penalty (9,000kg total) launched weekly: 374,300kg yearly. Tube capacity multiple requirement: 6,768,164 times.

Boeing Delta-IV HLV expendable cargo rocket: 22,000kg with a 15% tankage penalty (25,800kg total) launched every two months: 131,580kg yearly. Tube capacity multiple requirement: 2,379,255 times.

Nasa/United Space "Shuttle Z" SDV HLLV expendable cargo rocket: 108,000kg with 10% tankage penalty (120,000kg total) launched thrice yearly: 324,000kg yearly. tube capacity multiple requirement: 5,858,630 times.

I assume you should now be able to see a pattern.

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#201 2004-03-11 15:03:58

Re: Physics transfers fuel inside carbon nano tube - fuel into space

#202 2004-03-11 15:47:10

Re: Physics transfers fuel inside carbon nano tube - fuel into space

#203 2004-03-11 20:29:54

Re: Physics transfers fuel inside carbon nano tube - fuel into space

#204 2004-03-11 21:17:21

Re: Physics transfers fuel inside carbon nano tube - fuel into space

#205 2004-03-11 23:19:49

Re: Physics transfers fuel inside carbon nano tube - fuel into space

#206 2004-03-12 00:17:24

Re: Physics transfers fuel inside carbon nano tube - fuel into space

#207 2004-03-12 00:37:48

Re: Physics transfers fuel inside carbon nano tube - fuel into space

#208 2004-03-12 00:59:07

Re: Physics transfers fuel inside carbon nano tube - fuel into space

#209 2004-03-12 01:11:33

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#210 2004-03-12 01:16:03

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#211 2004-03-12 01:27:57

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#212 2004-03-12 01:35:36

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#213 2004-03-12 01:45:09

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#214 2004-03-12 01:49:12

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#215 2004-03-12 01:50:24

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#216 2004-03-12 01:56:07

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#217 2004-03-12 02:03:06

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#218 2004-03-12 02:14:37

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#219 2004-03-12 02:33:18

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#220 2004-03-12 02:37:27

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#221 2004-03-12 09:36:01

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#222 2004-03-12 10:07:33

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#223 2004-03-12 10:24:05

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#224 2004-03-12 10:34:14

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#225 2004-03-12 10:44:05

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