A Space Elevator Draft

[FallingPhoenix]

And then people who have no understanding of the subject and who think that "theoretical" means that they can make up any old bullshit started making excuses and claiming that they knew better than scientists.

Maybe they've just read different papers than you have?

 

[Tenacious-Techhunter]

NASA has never tested “space tethers”, because the basic material limitations were simply impossible to implement at the time; they knew the math didn’t work out yet, but might in the future. Now we have carbon nanotubes, and we’ll see how that goes.

You haven't met a fact you didn't like and tried to discredit someone have you?

Deployed as secondary payloads on GPS launches - http://www.nasa.gov/centers/marshall/pdf/337451main_Tethers_In_Space_Handbook_Section_1_2.pdf

STS-75 space electricity experiment - http://www-spof.gsfc.nasa.gov/Education/wtether.html

And hey, whaddya know, a whole Wikipedia page listing a bunch of space tether experiments, from Gemini, through the Shuttle and beyond - https://en.wikipedia.org/wiki/Space_tether_missions.

So.... please tell us again how NASA has never tested these? Early experiments didn't use carbon nanotubes. They were experiments, they used existing materials such as kevlar or other currently available materials. The biggest problem they faced (or would, with long-term exposure) is that objects in low-earth orbit degrade faster due to things like UV exposure, atomic oxygen, ionizing radiation, etc. In fact, NASA experimented with this, too. Now please tell me NASA never deployed the Long Duration Exposure Facility. Carbon nanotubes should not have these same issues. However, until we have more experiments to prove out these theories, we don't truly know.

They weren’t testing the tethers... they were using the tethers for a purpose unrelated to space elevators. Just like they weren’t testing airbag lithobraking on Mars; they were just using it. The tethers, in those cases, were merely a mechanism being used for their intended purpose. None of it had anything to do with space elevators. It’s a complete red-herring not applicable to this argument.

 

[Tenacious-Techhunter]

There's an entire sub-set of engineering principles that had to be created to help counter-act the swaying (they are called mass dampers). I forget which building in Chicago has it, but it's mass damper is a just a giant block of steel that is set on top of a liquid and as the building shifts one way, it shifts the other. It's very simple, but very neat.

Mass-dampers are a red-herring here; as you say, they are designed to prevent swaying; but the point here is that the cable must sway; the mechanics involved don’t allow for a rigid member.

 

[Tenacious-Techhunter]

You pointed out tether wasn't the right term... You continue to try (and fail) to attack others positions and statements by trying to split hairs and not actually addressing the question (which, by the way, was directed towards TT who incorrectly said NASA had never done any space experiments with tethers).

You tried to state that NASA had experimented with Space Elevator Tethers before. You were flat out wrong, and I said so. Then, you tried to move the goalposts so you could still be correct about something, in spite of being dead wrong about the original point. You’re just a coward that can’t admit when he’s been called out for his bull@^*%.

You have not cited any facts in your rebuttal (for instance a Canadian company has an actual patent on a 12mile space elevator. Did you even know that?)

In order to have a Patent, they have to have a working example. At most, they can have their Patent be “pending”...

I was defending Shawn him here because he isn't terribly off base with what he's putting out there.

Yes, yes it is. It’s a solid structure that would fracture before it would reach a height useful for its intended purpose. The shear loads would outright kill it.

His illustrations aren't terribly different than others that have come before him.

Yes, his perpetuation of ignorance is exactly the problem. That’s why we’re telling him to stop it.

 

[Tenacious-Techhunter]

And then people who have no understanding of the subject and who think that "theoretical" means that they can make up any old bullshit started making excuses and claiming that they knew better than scientists.

Maybe they've just read different papers than you have?

Maybe they just google “NASA” and “tether”, and post references without actually reading them.

 

[phavoc]

And then people who have no understanding of the subject and who think that "theoretical" means that they can make up any old bullshit started making excuses and claiming that they knew better than scientists.

Maybe they've just read different papers than you have?

Maybe they just google “NASA” and “tether”, and post references without actually reading them.

Or maybe you are just too arrogant and self centered yo realize that you haven't a clue?

The point is you were flat out wrong and proof was provided. You cant accept being wrong.

You also make wild statements with no evidence to back them up.

And your pathetic attempts at being a cyber bully fail time and again. It's probably time to change your handle, again.

And you flat out make assumptions about people you kow nothing about their background, experiences or education.

Yep, it's a simple waste of time and text debating wirh you. Back on to ignore you go!

 

[phavoc]

And then people who have no understanding of the subject and who think that "theoretical" means that they can make up any old bullshit started making excuses and claiming that they knew better than scientists.

Maybe they've just read different papers than you have?

Maybe they just google “NASA” and “tether”, and post references without actually reading them.

Or maybe you are just too arrogant and self centered yo realize that you haven't a clue?

The point is you were flat out wrong and proof was provided. You cant accept being wrong.

You also make wild statements with no evidence to back them up.

And your pathetic attempts at being a cyber bully fail time and again. It's probably time to change your handle, again.

And you flat out make assumptions about people you kow nothing about their background, experiences or education.

Yep, it's a simple waste of time and text debating wirh you. Back on to ignore you go!

 

[phavoc]

So maybe if we said "That's a pretty sweet picture, if you're interested, here's some cool information on space elevators that I really like and might help your concept" and then let it go, it would inspire people to want to learn more.

That's exactly what I did. And then people who have no understanding of the subject and who think that "theoretical" means that they can make up any old bullshit started making excuses and claiming that they knew better than scientists.

But whatever. Do whatever the hell you want.

Again, attacks, yet no actual point. You've yet to discredit anything anyone else has said. Oh, right, you cited "that's not science"

Put your science up dude. Cite something other than your opinion.

See a person who had an argument would counter with facts. You've yet to do so. Instead you try and bully others and nobody cares.

Oh, you did use the classic playground comeback "whatever". Nice....

 

[Tenacious-Techhunter]

Maybe they've just read different papers than you have?

Maybe they just google “NASA” and “tether”, and post references without actually reading them.

Or maybe you are just too arrogant and self centered yo realize that you haven't a clue?

The point is you were flat out wrong and proof was provided. You cant accept being wrong.

You also make wild statements with no evidence to back them up.

And your pathetic attempts at being a cyber bully fail time and again. It's probably time to change your handle, again.

And you flat out make assumptions about people you kow nothing about their background, experiences or education.

Yep, it's a simple waste of time and text debating wirh you. Back on to ignore you go!

Guess I called it. You just don’t read, do you?

I wasn’t wrong, you just moved the goalposts so that you could be right about something.

If I thought a backed up statement mattered to Driscoll, I would have backed it up with facts. But then someone else comes in and backs it up for me, and you give him nothing but grief. Bravo.

I’m not trying to bully anyone; I’m trying to extinguish ignorance. People are not entitled to remain ignorant. The moment they are confronted by an undeniable fact, they must acknowledge it and move on. But you prefer the comfort of your ignorance, so you see it as bullying.

This is the only handle I’ve ever used here. If you think I’m someone else, that’s your own malfunction.

 

[FallingPhoenix]

I’m not trying to bully anyone; I’m trying to extinguish ignorance. People are not entitled to remain ignorant. The moment they are confronted by an undeniable fact, they must acknowledge it and move on. But you prefer the comfort of your ignorance, so you see it as bullying.

The problem seems to me to be that, to you, current theory is "undeniable fact", whereas others seem to want to keep their options open and want working examples before they consider it "undeniable fact".

I don't see why one position has to be "right" and the other "wrong", especially in the context of science fiction.

 

[Tenacious-Techhunter]

I’m not trying to bully anyone; I’m trying to extinguish ignorance. People are not entitled to remain ignorant. The moment they are confronted by an undeniable fact, they must acknowledge it and move on. But you prefer the comfort of your ignorance, so you see it as bullying.

The problem seems to me to be that, to you, current theory is "undeniable fact", whereas others seem to want to keep their options open and want working examples before they consider it "undeniable fact".

I don't see why one position has to be "right" and the other "wrong", especially in the context of science fiction.

It’s purely a matter of the physical constraints involved. The shear stresses from atmosphere pushing and pulling on the cables laterally in different directions depending on altitude, the tension, relaxation, and shear stresses from minor orbital drifts and corrections, the need to correct for harmonic resonances, all these things lead to a necessarily flexible design. A rigid design just wouldn’t work; the choice of materials is simply irrelevant, because they just don’t match the design constraints.

If there were any grey area here, there would have been designs to that effect; not merely because NASA engineers are creative, but because they start from the design constraints. They know what fits before they start, and they work within those limits. “Use Carbon Fiber” isn’t a design constraint; using “a connector material with at least this much tensile strength and at least this much shear strength” is. You don’t need to ship something to space to test for that; you test for that on the ground, know it isn’t good enough, and move on to the next thing. We have never had a material suitable for space elevators before; and, in terms of manufacturability at least, we still don’t. Regardless, any design that doesn’t at least respect the concept of those constraints is done in ignorance. Better to acknowledge that, and either correct it, or acknowledge that its relevance to a given game is limited.

Ships and technology built with an understanding of the design constraints involved are simply more relevant to more games; and relevance is a legitimate critique.

 

[FallingPhoenix]

I’m not trying to bully anyone; I’m trying to extinguish ignorance. People are not entitled to remain ignorant. The moment they are confronted by an undeniable fact, they must acknowledge it and move on. But you prefer the comfort of your ignorance, so you see it as bullying.

The problem seems to me to be that, to you, current theory is "undeniable fact", whereas others seem to want to keep their options open and want working examples before they consider it "undeniable fact".

I don't see why one position has to be "right" and the other "wrong", especially in the context of science fiction.

It’s purely a matter of the physical constraints involved. The shear stresses from atmosphere pushing and pulling on the cables laterally in different directions depending on altitude, the tension, relaxation, and shear stresses from minor orbital drifts and corrections, the need to correct for harmonic resonances, all these things lead to a necessarily flexible design. A rigid design just wouldn’t work; the choice of materials is simply irrelevant, because they just don’t match the design constraints.

If there were any grey area here, there would have been designs to that effect; not merely because NASA engineers are creative, but because they start from the design constraints. They know what fits before they start, and they work within those limits. “Use Carbon Fiber” isn’t a design constraint; using “a connector material with at least this much tensile strength and at least this much shear strength” is. You don’t need to ship something to space to test for that; you test for that on the ground, know it isn’t good enough, and move on to the next thing. We have never had a material suitable for space elevators before; and, in terms of manufacturability at least, we still don’t. Regardless, any design that doesn’t at least respect the concept of those constraints is done in ignorance. Better to acknowledge that, and either correct it, or acknowledge that its relevance to a given game is limited.

Ships and technology built with an understanding of the design constraints involved are simply more relevant to more games; and relevance is a legitimate critique.

Okay, I can see that. Then again, like was said earlier, if you showed certain modern aircraft to an aeronautics engineer from the 1910s, I have a feeling they'd think you were ridiculous, given the design constraints, and I think that's where phavoc was coming from.

 

[ShawnDriscoll]

But whatever. Do whatever the hell you want.

I have permission. Thank the Gods.

 

[Tenacious-Techhunter]

Okay, I can see that. Then again, like was said earlier, if you showed certain modern aircraft to an aeronautics engineer from the 1910s, I have a feeling they'd think you were ridiculous, given the design constraints, and I think that's where phavoc was coming from.

Let’s have a look at that. Let’s kidnap Glenn Curtiss, and have him knock some plane ideas around, before we show him an F-22.

We tell him the performance requirements we want, ask him to design a plane that meets those requirements according to the physics that he knows, and see what we get.

Well, one thing he doesn’t know is the Whitcomb Area Rule, as that relates to supersonic aircraft; by extension, he doesn’t know about laminar flow, or even about the sound barrier, and associated shockwaves; he won’t even know about NACA’s research into airfoils. But he will know it has to have a narrow cross-section, that the wings won’t need to be particularly big to provide the necessary lift (and if they were bigger they would be more prone to breaking), and that it would be stronger, and much heavier, than he would be used to, and probably, somehow, made of lots of aluminum. He would also know that no engine he’s ever seen could run it, and that it would probably require quite a bit of mechanical engineering to have the required structural integrity, and may even need some materials in places he doesn’t know of.

Would he then, upon seeing the F-22, have a lot of questions? You betcha. But would he have been in the completely wrong ballpark? No. He’d nod, and go, “That’s about right.”.

See, the overall cross-section is a function of the available thrust at the desired speed, because of drag. The wing area is a function of the lift at that speed. The shape of the wing is a function of the diminishing returns on rigidity the further out along a spar you get. And what is left is more a less a box through the middle that you want to have a narrow cross-section, so it would be really long.

Now, admittedly, his design would have some shortcomings due to those things that were scientific discoveries after we kidnapped him. But it would more accurately match a Bachelor’s Degree Aerospace Mechanical Engineer’s attempt than you originally thought.


But what about the Space Elevator? What remains to be discovered there?
The Space Elevator problem is constrained by wind drag. Is there something we don’t know about wind drag we don’t know? Maybe, but probably not.
It’s also constrained by orbital mechanics. Is there something we don’t know about orbital mechanics? Maybe, but probably not.

The constraints on the problem are well-known. Just like Glenn Curtiss would have gotten the general shape right, in spite of not knowing how it would be powered, we can get certain general characteristics right, in spite of not knowing how to tether the thing to ground and space securely. Now, at this point, you might go, “But what about some awesome rigid super-material that has the required strengths? That would be a match for those fancy aerodynamics things that Curtiss didn’t know, right?”; well, then it would be some crazy big lever trying to wedge its way through the soft crust of the Earth; the mechanical complexity of the base would skyrocket. A flexible tether would just plain be easier. Those constraints the NASA engineers built their designs to exist for a reason.

 

[Condottiere]

I read somewhere that carbon nanotube aren't strong enough, so it won't be tech level eight.

Maybe spidersilk, we can have a hive of cyberspiders building one for us.

 

[Tenacious-Techhunter]

I was trying to find a comparison on the strength differences between carbon nanotube threads and spider silk threads, but, apparently, my searches are instead flooded with efforts to combine the two. So... yeah.

 

[phavoc]

I resumed work on my space elevator last night. It was modeled in Hexagon 1.21 using a repeated stack of links. I think it's 12km tall. Might be more than that. So I can repeat what I've built onto further stacks until it reaches some orbit height somewhere. But for close shots, I had enough of the elevator to work from for this Vue scene.

The longest part was just deciding how big the anchor should be and what that all looks like. I still have a lot of structure to add around the ground connection. I'm thinking of having the elevator go down a ways into the ground. But I still need something in the ground for the elevator shaft to hang onto. So that is being worked out.

This shot could be of a new (found) world. Vacant. For reasons, an elevator was approved first before any starport construction. Maybe the starport will be pre-fabbed on the spot, depending on what materials are left behind when the elevator is completed. If in twenty years, this world is expected to be a busy place, a class A starport will be attached near the base, along with a highport at the other end. Otherwise, it will default to a class C with just drones roaming the wastes until someone wants to make something out of the world.

I needed a real basic image like this for artifact use in a one-shot. Maybe two one-shots ago. So now I made time to make one for show-n-tell with players for the next time. Depending on how that elevator holds up, more stuff may get added to it for another possible one-shot.

Getting back to your original design...

The use of a hexagonal pattern is not a bad idea. A space elevator is going to have multiple cars traveling up/down simultaneously, therefore you will can utilize the square footage for the cars. Some designs have the elevator ending at a LEO position, while others extend all the way up to a geostationary position. The cable would most likely disappear into a base of some sorts. You are going to have loading/unloading area for the cars - who would be most likely unloaded elsewhere -. Depending on what kind of traffic is expected to traverse the tether, there should always be something loaded and waiting to be sent up. Especially if you have six tracks.

There have been some who cannot get into their head that science <> engineering (or theory vs. applied). To wit, using the miracle materials of the future doesn't preclude you from building a semi-rigid structure that can move as necessary. Or, from your illustration, you could easily have a cable at each corner of the hexagon that has a lateral brace (or another cable) connecting it to the other cables. This would provide even more support against wind shear. Engineers take what scientists create and discover and build actual things from it - and often they come up with uses and issues the scientists did not.

The only thing I would say about your idea is that I don't think anyone would expend resources to build this without first having someone there to utilize it. It would be a massive engineering effort and unless it's being built by von neumann machines in advance of colonization, it's just doesn't make fiscal sense.

 

[Tenacious-Techhunter]

The use of a hexagonal pattern is not a bad idea. A space elevator is going to have multiple cars traveling up/down simultaneously, therefore you will can utilize the square footage for the cars. Some designs have the elevator ending at a LEO position, while others extend all the way up to a geostationary position.

Counterweighting necessarily must extend past geostationary range; geostationary range is the point at which the centrifugal force stops being countered by gravity and the total force becomes zero; points beyond that, the centrifugal force becomes greater, and allows the tether to have a counterweight, which is necessary to keep it off the ground. If you need to lay cable that far anyway, you may as well make it useful.

There have been some who cannot get into their head that science <> engineering (or theory vs. applied). To wit, using the miracle materials of the future doesn't preclude you from building a semi-rigid structure that can move as necessary. Or, from your illustration, you could easily have a cable at each corner of the hexagon that has a lateral brace (or another cable) connecting it to the other cables. This would provide even more support against wind shear. Engineers take what scientists create and discover and build actual things from it - and often they come up with uses and issues the scientists did not.

This is not a matter of “engineering vs. science”; at some point, this thing needs to attach to the face of the planet, composed of purely natural materials. A rigid structure would just become some massive lever arm that wedges the planet’s crust open. So it simply has to be flexible, on account of the purely natural limitations of the planet itself. Better materials don’t change the underlying physical principles that constrain this design.

 

[FallingPhoenix]

There have been some who cannot get into their head that science <> engineering (or theory vs. applied). To wit, using the miracle materials of the future doesn't preclude you from building a semi-rigid structure that can move as necessary. Or, from your illustration, you could easily have a cable at each corner of the hexagon that has a lateral brace (or another cable) connecting it to the other cables. This would provide even more support against wind shear. Engineers take what scientists create and discover and build actual things from it - and often they come up with uses and issues the scientists did not.

This is not a matter of “engineering vs. science”; at some point, this thing needs to attach to the face of the planet, composed of purely natural materials. A rigid structure would just become some massive lever arm that wedges the planet’s crust open. So it simply has to be flexible, on account of the purely natural limitations of the planet itself. Better materials don’t change the underlying physical principles that constrain this design.

I took 'semi-rigid structure' to mean something like six cables bound by the hexagons to keep them from crashing into each other, which seems to me like it would act (on the large scale) a lot like a single (non-rigid) cable.

 

[ShawnDriscoll]

The draft has seven cables. The "hexes" can move up/down along the six outer cables. They don't touch the cables all that much, like how a maglev train doesn't touch its rails.