Obtainable Ringworld around the Earth?

--- In spacesettlers, "Lucio de Souza Coelho" wrote:

> Uh... If I understood correctly your explanation, the "railring"
> works as a kind of "counterweight" against the maglev ring. The
> maglevring would tend to rip itself apart outward, but the static
> (it would work better at zero speed instead of orbital speed) ring
> being attracted by Earth would press the thing inward.

Not exactly, though if that works, then I'm happy. The idea is that,
since the railring doesn't rotate (or at least doesn't rotate fast
enough to generate significant G's) you can make it as massive as you
like, until it's simply strong enough to resist the maglev ring's
efforts to rip itself apart.

You couldn't just rotate the whole thing, because as you beef it up to
make it stronger, you also beef it up and make it more massive. But
in this case, it can be as massive as you like.

> Yes, I think that would work without unobtanium. There would be moon
> and sun tides and stuff, by I guess that you can compensate that
> doing structures slightly flexible and with the orbital mechanics
> equivalent of "dilation gaps".

At this size, I suspect that a degree of flex is unavoidable.

> By the way, if that ring is constructed not at GEO but rather LEO,
> it would have an interesting property: the outer side of the
> "railring" would have natural gravity, close to 1g (say, 0.9 g or
> something), and pointing to the center of Earth. Both the outer and
> inner sides could be inhabited.

Now THIS is interesting! Cuts down on the living area, but...

But could it hold itself up at 0.9 G? That's why I had the thing at
orbital speed. But even if it is at orbital speed, why not have the
maglev ring inside zipping around in the direction opposite the
orbital? Then when it gets to exactly orbital speed in the opposite
direction, the maglev ring is stopped, and you have that 0.9 G for the
people living on it.