sky hooks

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sky hooks

Postby nfullmer on September 25th, 2010, 5:51 pm 

I'm new to this site, first post, and new to the science community as well. I don't really know where to post this at so i will post it on here and if told to post it on another part of this site.

I was looking up some stuff online and found this.

en.wikipedia.org/wiki/Space_elevator

In this article on Wikipedia they talk about cables for elevators. Why not use a vacuum like elevator.

I will give an example. An elevator to the moon can be accomplished to my thinking and my reasoning. Start out with a non movable base on a mountain. Lets say Pikes Peak in Colorado as a base. Then have a tube made of steal or some other extra strength material for the base. Then as the tube goes up into the atmosphere have the the tube as a lighter weight material.

Then in stationary orbit have a platform or something such as the International Space Station to tether the tube from the earth to space (I will give a mental illustration, think of holding a string taunt with both hands. One hand being the base the other hand being the space station.) And on that platform have a really powerful vacuum to suck the cab or object up to said platform. That would be the first leg of the journey.

Now to come down let it just free fall with a very powerful fan at the base to slow its momentum as it nears the earth.

Second leg all you need is a tube that people can drive in connecting the first space station to a second station. Kind of like a high way. And so on an so forth till you reach the moon.

Now you ask about asteroids and other cosmic debris in space. That is on the other hand complicated. You would need a shield of some sort to protect the occupants in transit. either a shield or a net of some sort. Also to shield the occupants from radiation and other such dangers in transit use tons of sun screen! Na just kidding. But some kind of suite would work out just fine. Such as the suites worn by tons of researchers.

That is just an idea i have been bouncing around in my head. Like I said it is just my opinion. Feel free to criticize my opinion. Sorry for any misspelling and/or grammar errors.

Thanks for listening
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Re: sky hooks

Postby CanadysPeak on September 25th, 2010, 5:58 pm 

nfullmer wrote:I'm new to this site, first post, and new to the science community as well. I don't really know where to post this at so i will post it on here and if told to post it on another part of this site.

I was looking up some stuff online and found this.

en.wikipedia.org/wiki/Space_elevator

In this article on Wikipedia they talk about cables for elevators. Why not use a vacuum like elevator.

I will give an example. An elevator to the moon can be accomplished to my thinking and my reasoning. Start out with a non movable base on a mountain. Lets say Pikes Peak in Colorado as a base. Then have a tube made of steal or some other extra strength material for the base. Then as the tube goes up into the atmosphere have the the tube as a lighter weight material.

Then in stationary orbit have a platform or something such as the International Space Station to tether the tube from the earth to space (I will give a mental illustration, think of holding a string taunt with both hands. One hand being the base the other hand being the space station.) And on that platform have a really powerful vacuum to suck the cab or object up to said platform. That would be the first leg of the journey.

Now to come down let it just free fall with a very powerful fan at the base to slow its momentum as it nears the earth.

Second leg all you need is a tube that people can drive in connecting the first space station to a second station. Kind of like a high way. And so on an so forth till you reach the moon.

Now you ask about asteroids and other cosmic debris in space. That is on the other hand complicated. You would need a shield of some sort to protect the occupants in transit. either a shield or a net of some sort. Also to shield the occupants from radiation and other such dangers in transit use tons of sun screen! Na just kidding. But some kind of suite would work out just fine. Such as the suites worn by tons of researchers.

That is just an idea i have been bouncing around in my head. Like I said it is just my opinion. Feel free to criticize my opinion. Sorry for any misspelling and/or grammar errors.

Thanks for listening


The problem is that vacuums don't suck.

There are some good thoughts out there about space elevators and how it might happen. Do a little Googling and you should find a ton.
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Re: sky hooks

Postby nfullmer on September 25th, 2010, 6:58 pm 

CanadysPeak wrote:
The problem is that vacuums don't suck.

There are some good thoughts out there about space elevators and how it might happen. Do a little Googling and you should find a ton.



well if vacuums don't suck then what do they do?? Just a question not meant to be offensive in nature.
I am just trying to figure out what a vacuum does if it does not suck.
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Re: sky hooks

Postby CanadysPeak on September 25th, 2010, 7:05 pm 

Vacuums don't do anything. Whatever is outside the vacuum pushes in. The vacuum just allows that to happen.
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Re: sky hooks

Postby neuro on September 26th, 2010, 2:00 pm 

nfullmer,
maybe it is more clear to you if you consider that there is already vacuum out there...
the tip pf your tube would be empty of air - even without any pumping/sucking - so you cannot suck anything.

gravity keeps the air close to the earth in the atmosphere, and has no wish to float up there, otherwise there would not be any vacuum, would there?
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Re: sky hooks

Postby Natural ChemE on September 26th, 2010, 8:16 pm 

nfullmer,

Say you take a huge air-tight tube that goes from the surface of the Earth to deep in outer space. And say that it's structurally viable (i.e., it doesn't break down and such).

If you completely empty that air-tight tube out of any gas, then place an elevator car at the bottom of it which air can't pass, and then allow air to enter below that elevator car, the elevator car will go up. It'll pretty much go up to the point where its downward pressure due to gravity cancels out the pressure of atmosphere at that level. It won't go up at all if the elevator car exerts more pressure due to gravity than exists at the base, or about 1 atm.

There are problems with this design. They include:
1. The elevator would be unrealistically expensive.
2. Structural problems would likely destroy it.
3. It would only be able to move an object up to the point where it equals out with atmospheric pressure. (That's not very high, if at all, for most heavy things. It's still basically only the upper atmosphere for even light things.)
4. The cost of evacuating a tube that large would be huge, and it'd need to be done each time.

This design could readily be improved by implementing a system which closes the vent to atmosphere at the base when the elevator is as high as it can go. You could then use a pump to push it up further. However, due to compression within the tube and the high cost of pumping, the elevator would be very slow and fairly expensive to move.

As a side note, I'd point out that your idea of a space elevator shares conceptual similarities with the idea of a blimp.
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Re: sky hooks

Postby nfullmer on October 12th, 2010, 2:11 pm 

Sorry i have been away for a little while. Like i said in my first post. it was just an idea i had. It can be improved on but i just figured i would give it a good go around.

Another thing i have that i will tie into the elevator is power distribution. What do we have an over abundance of on earth that can supply power? To me that would be wind. We use windmills to power the elevator. That gives us the power and to me if it has its own power source then to me that would mean the power company would not need any money so that just cut the costs in half. (I know it will never work because the way the earth works or government works everything has a company behind it and everyone gets a share of the money) However wind could supply the power. Like i said just a thought. So it might be expensive to build but not expensive to operate.
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Re: sky hooks

Postby CanadysPeak on October 12th, 2010, 7:37 pm 

nfullmer wrote:Sorry i have been away for a little while. Like i said in my first post. it was just an idea i had. It can be improved on but i just figured i would give it a good go around.

Another thing i have that i will tie into the elevator is power distribution. What do we have an over abundance of on earth that can supply power? To me that would be wind. We use windmills to power the elevator. That gives us the power and to me if it has its own power source then to me that would mean the power company would not need any money so that just cut the costs in half. (I know it will never work because the way the earth works or government works everything has a company behind it and everyone gets a share of the money) However wind could supply the power. Like i said just a thought. So it might be expensive to build but not expensive to operate.

This is a good project for speculation. It's been suggested by a number of people over the years, and it appears to have merit in its goals if not in its methodology. Dig in, do your homework, work out the economics of such a venture. It's good practice.
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Re: sky hooks

Postby Charles miller on March 8th, 2011, 12:51 am 

Good first try. With all science and engineering projects, "the devils in the details". So you need to understand the details.

What you suggested was build a real long strong soda straw, then suck on the end. Anything at the bottom of the straw would soon pop out the top.

The problem: the top of the straw already exists at zero pressure. It is open to space, you can't get a better vacuum than that. So to get air to flow up through the tube you have to increase its pressure at the bottom with some kind of a pump, not suck it out at the top. Think about your soda straw. If you can't reduce the pressure at the top where will the level of liquid in the straw be?
That's right, it will be just about at the same level as the liquid outside the straw. Air in your space tube will rise just as high as the top of the natural atmosphere and no higher. That's about a hundred miles up. Geo synchronous orbit is at about 23000 miles up.

Still the idea of pushing a light capsule up to the top of that very long tube using air pressure supplied from below has some advantages. All your heavy powerful machinery can be located solidly on the ground. There is no need for high strenght cables that we don't know how to make. We still would need to build the tube, that might require the same unavailable material but lets assume it does not. We know we can pump air. The question is how much energy will it require to pump it to the pressure needed. How high is that pressure? How much would a column of air 23000 miles long and one square inch in diameter, weigh? Is it possible to create that much air pressure and contain it within the materials we have? Have we come up against the problem of unavailable materials again? See? the devil truly is in the details.
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Re: sky hooks

Postby genemachine on March 9th, 2011, 8:06 pm 

We did an experiment in school on vacuums.

Given a large straw, we tried to suck water up to a third story window, but atmospheric pressure was not enough to push the water up the tube no matter how much we tried.
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Re: sky hooks

Postby Natural ChemE on March 9th, 2011, 9:01 pm 

genemachine wrote:We did an experiment in school on vacuums.

Given a large straw, we tried to suck water up to a third story window, but atmospheric pressure was not enough to push the water up the tube no matter how much we tried.


If you were able to suck hard enough to create a perfect vacuum, the water should've gone up the better part of 34 feet before the pressure equaled out (if you're at sea level). Still, I imagine that it'd be pretty tough to get such a strong vacuum going without using some sort of tool.

Since three stories probably equaled out to be around 34 feet, the vacuum pressure generated is about z/H atm, where z is the height the water went up and H was the height of the straw.
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Re: sky hooks

Postby CanadysPeak on March 10th, 2011, 4:45 pm 

Natural ChemE wrote:
genemachine wrote:We did an experiment in school on vacuums.

Given a large straw, we tried to suck water up to a third story window, but atmospheric pressure was not enough to push the water up the tube no matter how much we tried.


If you were able to suck hard enough to create a perfect vacuum, the water should've gone up the better part of 34 feet before the pressure equaled out (if you're at sea level). Still, I imagine that it'd be pretty tough to get such a strong vacuum going without using some sort of tool.

Since three stories probably equaled out to be around 34 feet, the vacuum pressure generated is about z/H atm, where z is the height the water went up and H was the height of the straw.


In fact, mechanical well pumps quit working at about 25 feet.
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Re: sky hooks

Postby genemachine on March 10th, 2011, 4:58 pm 

You americans and your crazy archaic units :)

It's been a while since I did this but I think this sum is correct..

1 atmosphere of pressure =~ 100,000Pa = 100,000 N/m2

gravitaional pull on 1kg (g) = 9.8 N (= 9.8 m/s2)

say our straw is 1m2 for simplicity

force of atmosphere = 100,000 N

can support 100,000/9.8 kg =~ 10000 kg

weight of 1mm of water in our giant straw = 1m*1m*1mm = 1,000,000 mm3 = 1kg

so we can support 10000mm of water = 10m
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Re: sky hooks

Postby Natural ChemE on March 10th, 2011, 6:52 pm 

Eq Ed Test 01.png


PS- Ick, didn't work out as well as I'd hoped. Ah wells; this is why God invented tests. Maybe I'll try splitting it up into a few shots or something next time.
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Re: sky hooks

Postby CanadysPeak on March 10th, 2011, 7:25 pm 

genemachine wrote:You americans and your crazy archaic units :)

It's been a while since I did this but I think this sum is correct..

1 atmosphere of pressure =~ 100,000Pa = 100,000 N/m2

gravitaional pull on 1kg (g) = 9.8 N (= 9.8 m/s2)

say our straw is 1m2 for simplicity

force of atmosphere = 100,000 N

can support 100,000/9.8 kg =~ 10000 kg

weight of 1mm of water in our giant straw = 1m*1m*1mm = 1,000,000 mm3 = 1kg

so we can support 10000mm of water = 10m


Keep giving us a hard time about units and I'll work it out in quintals per circular acre. :>)
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