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Artificial Gravity


mEarly1102
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Wernher von Braun proposed the wheel a long time ago in 1952. http://antwrp.gsfc.nasa.gov/apod/ap980328.html A ship would land by matching the rotational motion to the wheel and dock at its center hub.

 

I know it would take many many years to do, but how "simple" the idea is. The tube parts would be built on earth, or better yet, the moon, and hauled into space. The beauty of the wheel is in its construction. It can be built in sections with each section exactly the same. It would simply be joined in space.

 

In the beginning, it could be just a + ...four spokes with a section on each end and a center. Once spinning, gravity would be free. It could be added to as time permitted. As years go by, another "floor" could be added to it like a double decker.

 

God, I with they would start something like this now.

 

Bettina

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Wernher von Braun proposed the wheel a long time ago in 1952. http://antwrp.gsfc.nasa.gov/apod/ap980328.html A ship would land by matching the rotational motion to the wheel and dock at its center hub.

 

I know it would take many many years to do' date=' but how "simple" the idea is. The tube parts would be built on earth, or better yet, the moon, and hauled into space. The beauty of the wheel is in its construction. It can be built in sections with each section exactly the same. It would simply be joined in space.

 

In the beginning, it could be just a + ...four spokes with a section on each end and a center. Once spinning, gravity would be free. It could be added to as time permitted. As years go by, another "floor" could be added to it like a double decker.

 

God, I with they would start something like this now.

 

Bettina[/quote']

 

 

There would be signifigant engineering difficulties with that. The ISS is overly expensive and not overly useful as it is, nobody is going to build another one unless there is actually a decent reason to do so, which there is not. It would just be too expensive.

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Many experiments on the already breaking-down ISS require 0G to see what happens to certain things in microgravity. Adding artificial gravity means you'd need some way to have a section that was not spinning-which is hard enough. Stick with what you've got.

 

You could always have what you got for those experiments parked next to that wheel. ;)

 

Bettina

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  • 2 weeks later...

Just a note that centrafrugal force does not exist, i know, wierd right? What you are talking about it centropetal force, which is the attraction of an orbiting mass around a point mass.

 

This would have the desired result of creating an 'outward' force which in turn would allow the occupants to work more efficiently. This force would mean that their muscles/bones would not waste as they would have a 'load' on them.

 

The trouble is getting the rotation speed correct and stable. Also would your 'spinning' craft be an unsuported ring such as 'O' or would it be connected to a central object which causes the motion. If the latter it would be very hard to keep the craft stable as the ring and object would act on each other, pulling it out of orbit or off course.

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Wasn't DS9 a large cylindrical tube?

 

It appeared to be several miles in diameter and was rotating. All of the rooms and buildings were laid out on the inside of the tube and because of the rotation, that provided the artificial gravity.

 

If we built something like that, say 4 miles in diameter and 10 miles long, how fast would it hafta rotate to achieve 1G?

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No.

 

DS9' date=' and all of the Cardassian and Starfleet vessels, used artificial gravity generated by a grid of devices beneath the deck plating. And it wasn't miles in diameter; just over a kilometre if memory serves.[/quote']

 

I know that is true of the starships, but I was under the impression that the station was centrifugal.

 

Where does one access the technical specfications of DS9? :)

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Just a note that centrafrugal force does not exist' date=' i know, wierd right? What you are talking about it centropetal force, which is the attraction of an orbiting mass around a point mass.

 

This would have the desired result of creating an 'outward' force which in turn would allow the occupants to work more efficiently. This force would mean that their muscles/bones would not waste as they would have a 'load' on them.

 

The trouble is getting the rotation speed correct and stable. Also would your 'spinning' craft be an unsuported ring such as 'O' or would it be connected to a central object which causes the motion. If the latter it would be very hard to keep the craft stable as the ring and object would act on each other, pulling it out of orbit or off course.[/quote']

 

The central object you speak of would not be causing the motion. It would be just a hub connecting the four or more tubes to the outer ring. Much like I showed here in my earlier post.

 

http://antwrp.gsfc.nasa.gov/apod/ap980328.html

 

Another purpose of the hub would be to contain a large rocket engine that would be used to maintain the proper distance from earth.....not being fired very often if at all. This of course would be mounted underneath. The main purpose of the hub would be as a recreation center, etc, and quick access to any portion of the ring. I'm thinking this wheel would be HUGE. The concept is great because it could be added to in stages. It doesn't have to be a complet wheel right away....like I said before....just a +.

 

Also, mounted on the outer ring would be rocket engines to set the wheel in motion. Once spinning, the engines could be jetisoned and just small thrusters permanetly mounted on the ring would be enough to fine tune it now and then.

 

I don't understand your question of instability. Please explain that to me further.

 

Bettina

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i think quite applicable to this thread is severian's post #20 from the Why does rotation create gravity? thread which says:

 

Well, if we want the acceleration to be one standard gravity (9.81ms-2), and have one revolution per day (just like the Earth has):

 

The acceleration is 325cdaeb0632d9f677587c75ec162d53.gif where 6a810f92d35ac594e225156b0a137602.gif, then we need a radius of:

 

0d657affd39ec1a6633116902c3c7d52.gif

 

which for reference is about 1821 times the radius of the Earth....

 

 

If you want it to be the same radius as the Earth, 1e52d77cd034b12d18aa196ad587142d.gif then we need an angular velocity of:

 

05f3329a4600b798b64af8930cb628f9.gif which corresponds to a speed on the surface of f45c2cde3f788ef0a843d810e01809f2.gif which is roughly 24 times the speed of sound!

 

latex works... the quote looks good!!!!! :D

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i think quite applicable to this thread is severian's post #20 from the Why does rotation create gravity? thread which says:

 

 

 

now sadly our maths latex is not working *hint* admins! ;)... but' date=' well you should be able to get a rough idea of what's going on! or you could just look at the final figure![/quote']

 

When I was a kid, there was this ride at the county fair. You stood on a wheel with your back against a wall and the wheel started to rotate. As it rotated, the wheel was turned up on it's edge 90 degrees and the centrifugal force kept you from falling away from the wall, even when you were on the top and looking directly down. Wouldn't that be 1G?

 

We sure wasn't going as fast as the speed of sound because we could hear ourselves screaming.

 

Something is wrong with them figgers. :rolleyes:

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When I was a kid, there was this ride at the county fair. You stood on a wheel with your back against a wall and the wheel started to rotate. As it rotated, the wheel was turned up on it's edge 90 degrees and the centrifugal force kept you from falling away from the wall, even when you were on the top and looking directly down.

They still have that, I think it's called a gravitron.

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They still have that, I think it's called a gravitron.

 

As I understand the post by 5614, it would take a pretty fast rotation to simulate gravity by spinning a wheel as large as the Earth in diameter. Something like a surface speed of 24 times the speed of sound.

 

Did I get that right?

 

I recall that when they were training astranouts they used to put them through a certrafuge device where they spun them around in a chair on the end of an arm about 30 ft. long, and the got them up to several Gs and it looked like they were going around about 1 revolution pr. second, or 69 RPM.

 

I still say theres something wrong with them figgers.

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going around about 1 revolution pr. second' date=' or 69 RPM.

 

I still say theres something wrong with them figgers.

[/quote']

 

well i think there's a bigger problem with your conversion of 1 revolution per second into 69 RPM.... since when was there 69 seconds in a minute? ;)

 

i'll PM severian and get him to check those figures, i'll tell him to post here. i dont know all the maths to say its true, i just quoted him! but so far several people have looked at it and not said anything. but coming from severian, and Swansont, JaKiri & pmb all saw it, so i dunno... i'll PM him.

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I don't think there's anything wrong with the maths. Look at the statement before the figures.

Well, if we want the acceleration to be one standard gravity (9.81ms-2), and have one revolution per day (just like the Earth has):

The maths are for a space station that turns once per day.

 

In this debate there are two variables and one constant. The constant is of course the force needed to equal 1g. The two variables are dependent upon each other. The smaller the station, the faster it has to rotate.

 

The maths above is the answer to the question "How big would a station have to be to simulate gravity, if it turned once per day?"

 

Cheers.

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I don't think there's anything wrong with the maths. Look at the statement before the figures.

 

This is correct. As you say' date=' there are three unknowns, the accelaration (a), the radius ® and the angular velocity (omega, and related to that, v). Then there is one relation between them:

 

[math'] a = \omega^2 r[/math]

 

So if you want a for a specific omega, you must fix r, and if you want a for a specific r, you must fix omega. I was pointing out that the ring in Halo doesn't seem very realistic.

 

So, for the fairground ride, lets say it was 9.81m across (for obvious reasons ;) ), then for 1g

 

[math]\omega=\sqrt{\frac{a}{r}}=\sqrt{\frac{9.81 ms^{-2}}{9.81m}}=1 s^{-1}[/math]

 

In other words, you have to go round once a second, which corresponds to a speed of [math]v=\omega r = 9.81ms^{-1}[/math]

 

I don't think that is unreasonable...

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