FYS: Updated Ring Size

[jeriendhal]

Okay, going by cdk's suggestions, I'm going to increase the radius of the Ring to a nice even 100,000 km. This gives us a circumference of 628,318 km and allows the 1,000 km width I'd wanted without putting a permanent sunshade over the Earth. Total surface area counting oceans works out to a roomy 628 million sq km, not counting an approximately 10 km thick base for ocean depth and infrastructure.

As far as gravity goes, ignoring the mass of the Ring itself (since I have no idea what it would be) the rotational speed to maintain 1G would be 112,736 km/hr, making a full rotation around the Earth around ten times an hour. Which means, if it wasn't obvious before, the Ring is going to have to built of some kind of Unobtainium to hold together at that velocity.

As a side note, that definitely means the space elevators can't be physically connected to the Ring. I imagine there's some kind of anchoring platforms connected magnetically to the Roof, like a titanic maglev train. Moving people and cargo from the elevator's top and accelerating them to match the speed of the Ring's rotation would be pretty impressive.

Even more impressive would be how the Ring got moving that fast in the first place. I think it would involve a lot of ion engines running for a long time.

Comments

[resonant.livejournal.com]

I found the formula for gravity inside a ring, but my calculus is too rusty to try to figure it out.

[jeriendhal.livejournal.com]

I cheated and used this page

[lilfluff.livejournal.com]

Um...

When I put a 100,000,000 meter (100,000 kilometer) diameter ring spun to produce 1G into that calculator it says 0.00299 rotations per minute, or 0.17943 rotations per hour. (I do get the same rotational speed)

Considering that the bots had everyone on ice during construction, what's another few centuries waiting while an absurd number of ion drives mounted to the ring get it up to speed. Or a few solar powered mass driver tunnels inside the ring with weights spun in the opposite direction. Slow, but again with the Earth's population on ice there's plenty of time. Whatever was used is probably still used to help maintain stability.

I don't recall at the moment what they're called but smaller rings have been proposed for space colonies. (Does a quick trip to Wikipedia) Ah, Bishop Ring Habitats, which call for 1000 km radius and 500 km wide rings. Which gives 500,000 square kilometers of surface.

[jeriendhal.livejournal.com]

Rechecking I got the 0.00299, but multiplying by 60 to get per hour works out to 0.13794 rotations. Weird.

I do like the idea of using mass drivers for spinning up the Ring. More elegant (and less radioactive) than the ion drive, and with a little wiggle room built in they could probably be used for station-keeping.

Actually they're part of the design already, figuring in the transfer system to move things to and fro between the beanstalks and the Ring.

[mmegaera.livejournal.com]

And this is why I don't write science fiction [g].

[jeriendhal.livejournal.com]

OTOH I probably couldn't walk though Yellowstone's geyser fields blindfolded like you can. :)

[mmegaera.livejournal.com]

ROFL If I did that I might fall in!