Say I have a 800m-diameter, 200.000 Tons O'Neill cylinder that I want to make rotate at about 0.4 rev per minute.
How would I do that ? I'm talking about ways that already exist nowadays
>>7705520
easy, just attach it to the thumb you currently have jammed up your ass twisting uselessly..
>>7705520
>How would I do that ?
Rockets is the solution to anything that involves movement in space.
>>7705520
Attach to 8kw motor for 1 hour.
Add power corresponding to friction torque.
>>7705543
How would the motor work ? I'm thinking about a nuclear motor that would heat water. The steam would then lead to the movement of blades that would create a rotation power
>>7705520
it's probably in here m8:
http://www.nss.org/settlement/library.html
Of course, we need to know the moment of inertia to figure out what torque would need to be applied for so long.
Have a nice day.
>>7705739
This all depends on if this body is attached to a baseplate of some kind which is, heavier than 200 tons?
Shit son, if this is in space, you're gonna have to have some kind of massive source of compressed gas to release from points surrounding the center of mass of the system, facing specific directions.
Another way to get it to rotate is the Solar Wind, and big fat solar sails that also power whatever other shit you gotta power, ie test&measurement equipment.
I mean, sometimes, it could be useful to surmount the outer edge of that bigger ring with a strong toroidal electromagnet. This would definitely get both of them rotating at opposing rotational velocities, proportional to their masses. So your inner one would spin at 0.4 rev/min, while the outer one would be spinning considerably faster, due to its lower mass.
The only other way I could see getting this thing spinning would be with an EXTREMELY MASSIVE BASEPLATE and a steam-powered drivetrain.
Gotta think outside the box a little more OP.
Launched 2256
Decommissioned 2281
not worth the effort
>>7705520
stick some thrusters and a rocket on it and launch it into space
Thanks all.
In fact, it's already in space, and there's no bigger part like in >>7705766 "extremely massive baseplate"
I'm looking for a way to make it rotate for a long time. So no chemical propulsion
>>7705972
Then the winner would be either solar propulsion or electromagnetic propulsion, or some combination of both, but there is an easier way.
If you're in space, and there's no friction to worry about, a quick jettison of gas would honestly be the most efficient way to get that big of a thing moving.
Just get it in the right thrust vector (orthogonal to the axis of rotation) and let 'er rip, so to speak. The damn thing will spin until the tidal forces of larger bodies' gravitational influence change its angular velocity.
If you're looking for it to last longer than that, more jettisons may be required. In that case, a counter-rotational electromagnet powered by a solar sail could counterbalance this loss of angular momentum. Gas jets may still be needed to correct for gyroscopic instability, however.
If you really wanna get rid of any jets entirely, you'll have to exploit gyroscopic motion pretty heavily to keep the rotation stable over such a long period of time.
This thing may become gyroscopically unstable, and you will need to use either an asymmetry in the electromagnetic field of inductance, or a few weights positioned about the spin axis that can be transferred to different points that will influence the procession of rotation of the body.
Very complicated without jets.
>>7706015
Could ion thrusters be more powerful than just simple gaz jets ?
>>7705972
well you need something to press against to make it spin
An equivalent sized cylinder, end to end, being spun the opposite direction could suffice.
>>7706091
You would need an array of ion thrusters
And it would take some time, you would probably have to do the math on that.
>>7706091
Nope. Not in short term, not in long term.
Long term you would need to take advantage of other long-term energy sources, short-term, just kick-start it with a quick gas jet.
>>7705972
>I'm looking for a way to make it rotate for a long time. So no chemical propulsion
You only have to spin it up once. There's no drag in space, so it's not like you have to keep the motor running or it'll stop rotating.
You use chemical propulsion to get it up to speed, and then you turn off the rockets and you're done. If it does slow down for some reason, you turn them back on, and you're going to need to have chemical rockets anyway for station-keeping.
