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Artificial Gravity

Posted by: SuperShuki - Tue Feb 21, 2006 1:51 pm
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Artificial Gravity 

Could a pod/ spacecraft, attached to a long arm with a smaller weight at the end, be spun around an axis closer to the pod, thereby giving a smaller rate of rotation (allowing easier docking) while giving the same artificial gravity?
Yes 17%  17%  [ 1 ]
No 0%  0%  [ 0 ]
Maybe 83%  83%  [ 5 ]
Total votes : 6

Artificial Gravity 
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Post Artificial Gravity   Posted on: Tue Feb 21, 2006 1:51 pm
Could a pod/ spacecraft, attached to a long arm with a smaller weight at the end, be spun around an axis closer to the pod, thereby giving a smaller rate of rotation (allowing easier docking) while giving the same artificial gravity?

This is not a trick queestion- I don't know the answer (although I suspect yes)

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Post    Posted on: Tue Feb 21, 2006 3:17 pm
Yes and no.

Yes if you are planning to dock at the axis, because the RPM (Revolutions Per Minute) is lower.

No if you are planning to dock directly at the pod/spacecraft, because the pod is moving faster.

Gory details follow.

The formula for the magnitude of the centrifugal or centripetal acceleration is A=V^2/R, where A is the acceleration, R is the distance from the axis to the pod and V is the speed of the pod. Solving for V gives V=SQRT(A*R)

The circumference of a circle is 2*pi*R.

Assume you want A=9.8 m/s^2, which is about 1g. R will be the length of that part of the arm between the axis and pod. Here are two examples:

1)
Short arm, R=100 meters, V=SQRT(9.8*100) ~=31 m/s
Circumference of circle is 2*pi*100 ~=628 meters.
At ~31 m/s it takes 628/31 ~=20 seconds to go once around.

2)
Long arm, R=10,000 meters, V=SQRT(9.8*10,000) ~=313 m/s
Circumference of circle is 2*pi*10,000 ~=62,832 meters.
At ~313 m/s it takes 62,832/313 ~=200 seconds to go once around.

So the longer arm makes the RPM lower but the speed of the pod higher.


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Post    Posted on: Wed Feb 22, 2006 5:43 am
Ah ha :!: Another of those intuitive questions. Easy to set up a model to test as well so actually not as bad as the last effort about orbital mechanics if I remember correctly Super'. :) and having done just that rather than test the math, I'll agree with campbelp2002.

As an accountant, I'm used to getting people to tell me what they want 1+1 to equal rather than the other way around. :lol:

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Post    Posted on: Wed Feb 22, 2006 5:44 am
Ah ha :!: Another of those intuitive questions. Easy to set up a model to test as well so actually not as bad as the last effort about orbital mechanics if I remember correctly Super'. :) and having done just that rather than test the math, I'll agree with campbelp2002.

As an accountant, I'm used to getting people to tell me what they want 1+1 to equal rather than the other way around. :lol:

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Post    Posted on: Wed Feb 22, 2006 3:53 pm
You can say that again. :lol:


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Post    Posted on: Sun Apr 02, 2006 3:54 pm
The Wirtschaftswoche-article I already mentioned in another thread today is also reporting about special piezo-electric fiberswhich transmit impact-energy to a microprocessor. The processor generates a counter-oscillation within five milliseconds and thus reudces the impact.shock by more than 50%. It is used in the haft of tennis rackets.

Could that be used to to do the reverse in micro-gravity - so that it provides the effects upon feet, legs,..., the whole body which are provided by gravity normally?



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Post Yeah at the axis   Posted on: Sun Apr 02, 2006 5:47 pm
Yeah, at the axis. I was trying to find a solution to not having a spacecraft need to spin itself too much (if at all) when docking.

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Post    Posted on: Mon Apr 03, 2006 5:50 am
No Ekkehard, the effect would be just transitory, I imagine it partly cancels out a shock wave.

To produce artificial gravity, you need to produce a constant acceleration, to replicate the constant acceleration a body experiences in a gravity field. Our feet on the ground resist that aceleration, giving us weight.

The ways to replicate that in space are:

1) Firing your rocket engine. Unfortunately you run out of fuel in at most 20 minutes, and you end up going some where, really fast.

2) Spinning your vehicle/station to create centripetal acceleration. Unfortunately spin rates more than 2 revs per minute produce varying degrees of vertigo. and coriolis effects make walking in line with spin difficult. So a spin radius of more than 40 m is required for reasonable G, with minimal side effects. With current boosters, that means a lot of on-orbit construction of very strong & heavy modules.

3) Magnetic belts. An oldie but a goodie. Hard to manage due to the inverse square law. 1 G standing up, becomes 4 sitting down, becomes 100 laying on the deck. You wouldn't want to fall over! Astronauts with wheeled, granny, walking frames?

4) Gravity control device. Perfect solution. Unfortunately no one has figured out how to make one yet, (apart from possibly the recent trillionth of a G superconductor tests).


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Post    Posted on: Mon Apr 03, 2006 7:00 am
Hello, WannabeSpaceCadet,

my thought, my question merely was if the fibers could be used to achieve an effect revers to that used at the tennis-rackets and so to remove the need or requirement of artificial gravity.

To me it is clear that the fibers never will generate artificial gravity and that acceleration is required to create artificial gravity - I myself said it in 2004 in quite another thread here.

The idea is if the fibers might be used as something between the methods used to counteract the bad effects of microgravity and weightlessness on the body and artificial gravity.



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)


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