Space Elevators and Pipelines

John Creighton · 2004-11-26 18:01:50

http://earn.dlr.de/nea/01862.htm]here is some stuff on 1862 Apollo

This could be helpfull:
http://earn.dlr.de/nea/database.htm]Near Earth Asteroid Database

patrick · 2004-11-26 18:02:45

But the question is if the total area of horizontal cross section of the walls is less then 1/cm^2. Otherwise you pipe/cable will cost trillions to build.

The pressure from one pump to the next pump should be constant. The smaller the dimater the better because you can get away with a thinner wall thickness tube.

John Creighton · 2004-11-26 18:08:17

The smaller the dimater the better because you can get away with a thinner wall thickness tube.

That’s a good point. Of course it will come at the expense of increased viscous friction. But just maybe a high pressure narrow pipe is the way to go. Aim for about 80 pumping station, then it might be reasonable to target them with lasers. Each pumping station could have micrometer pumps in series to accumulate to a total pressure change of say 90 bars over a few meters.

John Creighton · 2004-11-26 18:10:15

The pressure from one pump to the next pump should be constant.

Why? I would think the pressure change at each pump or pumping station would be a parameter that would be later optimized.

John Creighton · 2004-11-26 18:11:16

Lets figure out the pipeline first then we can go to Eros?

Okay I am all ears.

patrick · 2004-11-26 18:27:44

The frictional loss can be compensated with higher discharge pressures between pumps.We did an experiment at work one day. We used Stainless Steel tubing 1/4 inch with a hydraulic hand held pump and tested the bursting pressure of the tubing. We pumped it up to over 22,000 pounds per square inch before it bursted. That wall thickness was less than 1/16 inch. If we had used 1 inch tubing it would have bursted much sooner.

John Creighton · 2004-11-26 18:33:25

The frictional loss can be compensated with higher discharge pressures between pumps.

Okay but if we want to keep the number of pumping stations down we are talking thousands of km between pumping stations. The cumulative effect of friction over these distances will be huge with any kind of flow rate. There is a limit in how high you can have the discharge pressure before the pipes start breaking down mechanically or chemically. We should look at some common gasses like air, hydrogen, methane and ammonia and ask how high can we raise the pressure before bad things start to happen inside the carbon nano tubes.

patrick · 2004-11-26 18:35:43

How about Nitrogen? Inert Gas.

John Creighton · 2004-11-26 18:36:17

We used Stainless Steel tubing 1/4 inch with a hydraulic hand held pump and tested the bursting pressure of the tubing. We pumped it up to over 22,000 pounds per square inch before it bursted. That wall thickness was less than 1/16 inch. If we had used 1 inch tubing it would have bursted much sooner.

Cool you actually work with this stuf. What do you do?

John Creighton · 2004-11-26 18:38:28

How about Nitrogen? Inert Gas.

Good point. As long as it doesn't leak through the pipe you should be able to get much higher pressures with nitrogen. We still need carbon though to make more pipes. That is why I asked about methane (CH4). We will need nitrogen on the moon and sense you can probably pump it to a higher pressure may it should have its own pipe.

patrick · 2004-11-26 19:00:30

I used to be a control room operator at a fossil power plant in Florida for FP&L.

John Creighton · 2004-11-26 19:05:03

Lets see the strength of carbon nanotubes is 150*10^9 N/m^3 so what is a reasonable load for it to support we don’t want anyone to pull to hard and bring the who thing down. Lets say at the minimum 100 kg. Probably one tone is a safer number but lets work with the minimum for now. To support 100 kilograms we would need an area of:
100 kg/(150*10^9 N/m^2)/(9.8 m/s^2)= 6.8027e-011 m^2*((1e6 um)^2/(1m^2))
=68.0270 square micro meters. Okay lets make the pipe a few hundred micro meters in diameter. At most a millimeter.

patrick · 2004-11-26 19:13:29

Don't know the math. I just know they say the material is strong enough. How thick does it have to be? How about the same thickness as the Stainless Steel tubing? How much pressure would that withstand? If it is alot then you don't need as many pumps???? Also, I am ERRORIST and am visiting my sister in Fla now.

John Creighton · 2004-11-26 19:26:41

Don't know the math. I just know they say the material is strong enough. How thick does it have to be? How about the same thickness as the Stainless Steel tubing? How much pressure would that withstand? If it is alot then you don't need as many pumps?

Well lets see the tension in the walls of a cylinder is PR. If the pressure is 90 bars and the radius is 100 micro meters we have:

T=(90 Atmospheres*(101 e3 pa/atmosphere))*(100e-6 m)
=909 pa/m=909 N/m^3
The strength of carbon nanotubes is 150*10^9 N/m^2 so the thickness of the walls would be:
W=(909 N/m^3)/(105*10^9 N/m^2)= 8.6571e-009 m
Or 8.6571 nano meters.

Now clearly if the walls are that thin the gas will leak out. Make the pressure support part of the walls 1 micro meter and make the load supporting part of the walls with 86 micrometers squared of material. We are talking about a very small tube that can support much more then 90 bars.

John Creighton · 2004-11-26 19:27:55

Also, I am ERRORIST and am visiting my sister in Fla now.

Go figure.

patrick · 2004-11-26 19:30:49

How about a tube wall thickness of .333 and an inside tube diameter of 1/4 inch??

John Creighton · 2004-11-26 19:37:12

Oh wait with a radius of 100 micrometers and only using 86 m^2 to support the load the wall thinness of the load supporting part would be:
86/(100/2)=1.72 micro meters. I want the load supporting part to be at least 10 times as thick as the pressure supporting part. So the area of material for the load supporting par would be greater then 10 um*(100um/2)=1000m um^2. This is good because now are cable can support one tone of load on the ground. I must be making some mistake these dimensions sound too small. Can this stuff really be that strong? Anyway right now we are look at a tube 200 micrometers in diameter with pressure supporting part of the walls 1 micrometer thick and the load supporting part of the walls 10 micrometers thick. I will check these numbers later.

John Creighton · 2004-11-26 19:39:43

How about a tube wall thickness of .333 and an inside tube diameter of 1/4 inch??

It will weigh over 1000 tons and cost trillions to build. We have to think smaller for the first pipe.

patrick · 2004-11-26 19:42:06

Surely carbon is not that expensive??

John Creighton · 2004-11-26 19:48:55

Surely carbon is not that expensive??

There is currently no cheep way to get it into orbit. That is why I was asking about asteroids. Unfortunately most NEO are S type asteroids and not C type asteroids.

patrick · 2004-11-26 19:52:03

Well, the hyper X plane will be 100 times cheaper. Per pound.
Can you shoot it up in a particle beam?

John Creighton · 2004-11-26 19:57:20

Well, the hyper X plane will be 100 times cheaper. Per pound.

Okay well then we will have to wait for the hyper x plain to build your ¼ inch diameter pipeline. If we could build a small pipeline that pumped carbon to space then we might not have to wait for hyper x. Your choice. Or we could continuously make little pipelines out of the carbon pumped up into space. They could be woven together to increase there overall strength. They could share redundancies in the pumping station and we won’t have to wait for hyper x to build them(just incredible material science). The key is to try and achieve the greatest good in the shortest time.

John Creighton · 2004-11-26 20:00:57

Can you shoot it up in a particle beam?

Hmmm....I bet if GCNRevenger was following this he would of predicted you would suggest that. The problem with this method is you would need an incredibly huge apparatus to capture the particle beam. It is still going to be incredibly expensive to build. I may try and tackle this at a later time but not today and in another dissuasion.

patrick · 2004-11-26 20:01:35

Can we lower a small one from the ISS if it was in a geo. orbit?

John Creighton · 2004-11-26 20:03:48

Can we lower a small one from the ISS if it was in a geo. orbit?

What is the point of this comment. The ISS is not in GEO and we do not have such a cable in GEO. The key is to get such a cable to GEO cheaply. Lets not discuss ideas that aren’t real.

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