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ghgh
Full Member
Still trying to make kinetics work.
Posts: 136
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Post by ghgh on Jul 14, 2018 0:41:47 GMT
So according to (http://www.calctool.org/CALC/phys/newtonian/centrifugal) centrifugal force calculator, spinning a 450m centrifuge at 1.45rpm is enough to simulate 1.06G of acceleration.
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Post by AtomHeartDragon on Jul 14, 2018 8:34:42 GMT
You probably don't want more than 1rpm, it tends to make people queasy.
Then again, you can probably do with less than 1G.
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ghgh
Full Member
Still trying to make kinetics work.
Posts: 136
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Post by ghgh on Jul 14, 2018 15:58:44 GMT
1 rpm would get you 0.5 G which is more than Mars (0.38G). On the other hand, going too low on gravity would cause bone/muscle/blood loss for prolonged periods of time, and we don't have enough data to know if humans can adapt to Mars gravity without serious health consequences (The Mars Gravity Biosatellite WOULD have provided us with this information but the program died in 2009.....). Looks like I need a wider diameter. At 10km I'd only need 0.3 rpm.
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Post by alias72 on Jul 15, 2018 14:26:45 GMT
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ghgh
Full Member
Still trying to make kinetics work.
Posts: 136
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Post by ghgh on Jul 15, 2018 15:16:28 GMT
That's a good calculator, seems a bit outdated though. The sources seem a bit suspect too especially when the author states;
"Hill & Schnitzer don’t explain their minimum limit of 0.035 g. Compared to the others, it’s an outlier that appears to be an arbitrary lower bound on their logarithmic graph."
or
"Gilruth doesn’t explain his maximum limit of 0.9 g. It may be to allow for additional Coriolis accelerations without exceeding a total of 1.0 g. This would be better addressed by minimizing the Coriolis accelerations, by maximizing the tangential velocity."
or
"I have no data on the upper limit of “comfortable” acceleration. I’ve guesstimated values at which the indicator should transition from green to yellow to red. You may think that I’ve set these limits too low."
His sources are Sci-fi authors who make arbitrary limits. I think this whole field of what amount of microgravity is comfortable just needs more data. Hopefully with all this talk about exploring Mars, people will start investing in centrifuges again.
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Post by apophys on Jul 17, 2018 8:30:18 GMT
You probably don't want more than 1rpm, it tends to make people queasy. Then again, you can probably do with less than 1G. People can adapt to 4-6 RPM without serious issues; testing has shown this. Additionally, queasiness is linked to having the otolith organs in the inner ear stimulated in complex ways, as a result of having a rotating test platform on a rotating Earth. Space habitats are expected to have reduced queasiness compared to experiments, due to not being on a rotating Earth.
On the other hand, there is basically no testing on the safe lower limit for gravity (or the safe upper limit, for that matter). All we really know is that 1 G is clearly fine, and 0 G is lethal in the long term. Moreover, a real colony will need to have pregnancy and childbirth taken care of on-site; having too low gravity could be disastrous for fetal and child development. So it makes sense to be conservative and aim for 1 G, even at the cost of a little short-term unpleasantness if necessary. Best guesses do not apply when the stakes are high and there is no data.
(might need to find a cached version if it's offline, like I'm seeing now)
6 RPM corresponds to a radius of 25 meters, for 1 G. So anything larger than a 25 meter radius is fine.
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ghgh
Full Member
Still trying to make kinetics work.
Posts: 136
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Post by ghgh on Jul 17, 2018 22:59:10 GMT
Well then I guess 1.4 RPM is fine then? Now that the station is livable, I need to find a reason why people would want to live in a cramped magnesium cylinder. I'm thinking cargo bays, lots and lots of cargo bays.
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