Restoring a ring world?

[keynes2.0]

Part of what is causing the issue is your calculations are not taking into account the same gravity or rather simulated gravity everyone else is.

Artificial gravity is in fact the one and only factor I thought significant enough to include. The acceleration of artificial gravity would be 1 G in my reckoning. There are many things that can sustain a sheer force of 1 G. A simple wooden bridge sustains a force of 1 G. The effect is purely localized although the sheer force would be slightly greater in some locations because the design wouldn't be perfectly uniform.

Please tell me why you think there would be a force vastly in excess of 1 G.

 

[Aldregan]

Artificial gravity is in fact the one and only factor I thought significant enough to include. The acceleration of artificial gravity would be 1 G in my reckoning. There are many things that can sustain a sheer force of 1 G. A simple wooden bridge sustains a force of 1 G. The effect is purely localized although the sheer force would be slightly greater in some locations because the design wouldn't be perfectly uniform.

Please tell me why you think there would be a force vastly in excess of 1 G.

Based on hoop stress of a ring, the material needs to be able to withstand insane amount of ring stress. I don't have the formula handy but calculate the thin walled hoops stress of a ring with 149 million kilometer radius with a tangential velocity of 1,208,797 meters per second. Compression strength isn't an issue, its tensile strength.

 

[keynes2.0]

@Aldregan

Correct me if I'm wrong but hoop stress has to do with pressure such as that in a pipe carrying a high pressure fluid, not centrifugal acceleration.

 

[Aldregan]

Correct me if I'm wrong but hoop stress has to do with internal pressure such as that in a pipe carrying a high pressure fluid, not centrifugal acceleration.

It may be, I haven't done engineering in a decade. I do remember calculating the sheer stresses of a ringworld a long time ago. There was a reason Niven made up Skrith to be the base material since no known metal could withstand the forces required for the spinning ring. Your math works fine if the ring doesn't spin.

 

[keynes2.0]

Applying the wikipedia calculations for a flywheel to this situation seems to reduce down to

tensile stress = density*r*9.8

so that would mean that the stress is directly proportional to the radius. So I guess gravity by solar rotation is completely out.

 

[Aldregan]

Applying the wikipedia calculations for a flywheel to this situation seems to reduce down to

tensile stress = density*r*9.8

so that would mean that the stress is directly proportional to the radius. So I guess gravity by solar rotation is completely out.

For now. A smaller ring would bring it into the realm of reality, or we figure out how to make scrith

Ringworld by way of gravity fields is still on the table.

One thing about humans, once we get an idea in our head, we make it a reality even if physics screams no!

 

[Enkal]

There would be no need to "spin up the ring", it would be spinning from get go. Also the gravity of the sun would counteract some of the centrifugal forces, photon pressure would push on the structure as well though. One reason for consuming all planets in the system would be to avoid complicated gravitational forces on the structure.

When it comes to mining, with the tech levels we talk about you would just let lose self-replicating nanomachines that would consume the planets and then build the ring using the same machines. This game lacks all the interesting aspects of nano tech imho. At the far end of the research tree there should be "femto-tech" which is where you manipulate the elementary particles instead of complete atoms. I can think of a number of techs and events relating to these that could make the game much more interesting in the mid-end game.

 

[Cannes]

Pretty sure you can't keep the structure in a stable position without spinning it.

 

[Enkal]

Orbital mechanics dicates that it will be rotating anyway. Everything in orbit around a star will rotate around the star, does not matter if it is a planet or a ring-world.

 

[Cannes]

Rofl at whomever downrepped my above post!
To put some perspective on how utterly, ridiculously even, flimsy the proposed structure is:
If you build this ringworld with approx 1 au radius(Which according to the physicistd at pbs is way to close to be even remotely feasible.) 10km wide and 1km thick.
Scale this structure down to the size of a sportsarena and the 10km width becomes much less than the depth of the grooves in your fingerprint (Courtesy of Neil deGrasse Tyson) and 1km thickness becomes microscopic. Which brings me back to my original point some pages ago. You need way way more material than 2% of earths mass to even begin thinking of such a structure.

 

[Highlordelliot]

You can´t.

Restoring ring worlds also wouldn´t be worth it, they are just simple 4x25 slots gaiaworlds. The real value is that you find ancient factorys on them, which are better then anything you can ever build, and without it they are not really that usefull. If you really intended to repair one ringworld it would cost you so much minerals that you could just built a "conquer the whole galaxy doom stack" instead.

Perhaps my nation wants to use the vast resources at our disposal that seem practically endless to go on a massive vanity project such as this.[/QUOTE]

 

[keynes2.0]

Scale this structure down to the size of a sportsarena and the 10km width becomes much less than the depth of the grooves in your fingerprint (Courtesy of Neil deGrasse Tyson) and 1km thickness becomes microscopic.

So what?

 

[GloatingSwine]

Remember that the edges of the ring have 100km high walls to keep the atmosphere in. If you made it only 10km wide (not eg. 1.6 million km like the original Ringworld) you'd occlude most of the light from the surface (And maximising light to surface is one of the key reasons to build a megastructure like this).

 

[Talanic]

Assuming you manage to build your ringworld - with a radius of 1 AU and without destroying Earth - you're going to want to change how big it is.

Because otherwise, it's going to be run over by a planet. Or - assuming you have it at an offset angle, overlapping Earth's elliptical orbit only at two points - get messed up by Earth's gravity when the planet makes a close pass.

 

[Cannes]

So what?

There are no known materials that could cope with the stress of orbit in such a fashion.

 

[keynes2.0]

There are no known materials that could cope with the stress of orbit in such a fashion.

This is completely unrelated to the width. It's a function of the radius only.

Remember that the edges of the ring have 100km high walls to keep the atmosphere in.

Or a ceiling? Seems a lot more straightforward. You would have to keep replacing the glass panes taken out by meterorites but it's a lot less work then the 100km high walls.

 

[BlackUmbrellas]

Regardless of the science behind it (which is really rather irrelevant to Stellaris and its soft-scifi), I definitely think the ability to restore (or even build) ringworlds would be a nice addition to the game. I feel that an endgame civilization should have the potential to equal or exceed the Fallen Empires.

 

[Cannes]

This is completely unrelated to the width. It's a function of the radius only.

Wait... what? How the hell is the structural integrity of the entire structure unrelated to the stresses of orbiting a star?
Please take another look at the comparison I made. Just think about it for a minute. You have a HUGE ring around an entire star and you want to make it ultra thin...
It's really obvious how its never going to fly. Others have already pointed out that your structure could never cope with being rotated and you even agreed to it! Yet you still close your eyes to realities!
How would you even go about building it without orbiting? Build it somewhere else in the universe and then ferry it into place around the star?

If you somehow managed this ridiculous feat, then you will have to start dealing with the gravitational differences as the star moves and wobbles its way around the galactic center. Your flimsy structure would quickly tear itself apart even though as you point out the gravitaitonal force of a star at that difference seems small, when compared to gravity on the surface of earth, however when dealing with a megastructure like this those forces become massive. As soon as one single part of the structure fails the entire ring collapses directly into the star.

 

[keynes2.0]

Wait... what? How the hell is the structural integrity of the entire structure unrelated to the stresses of orbiting a star?

How the hell is that what I said?

 

[Cannes]

How the hell is that what I said?

I was very clearly talking about the dimensions of the proposed ringworld. And illustrating how thin and stretched out it would be. You don't think that plays a role in its structural integrity? We are most certainly not building wooden bridges on earth here...