Space Elevator Car - First Draft

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Space Elevator Car - First Draft

Postby CoffeeBot » Sun Jul 31, 2005 12:00 am

Here's what chuck and I have come up with this delightful little design for the space elevator car. The original design sketch is posted here.

My biggest beef is with how the metal textures came out...not all of the effects on them came out equally sized, so you can really see a difference in pieces. Also, I'm not keen on how the windows turned out (there's too many, for one). Need to work on that.

It should also be noted that the post running through the center is a guide post, used only when the car is docking at it's desitnation. It runs on a series of nanotube ribbons. As chuck described them:
chuck_starchaser wrote:They'd be very sheer, like pantyhose. The color of nanotube fabric, I'm not sure; I think they come in a variety of colors depending on the molecule type --there are various numbers of carbon atoms per turn, and "twist" numbers that make different molecules, which are all still called nanotubes, but should have all kinds of colors, so I'd pick one at random.

I think the random color we had spoken of in another thread was a reddish color...but it's not set in stone. So, envision eight misty, thin, pantyhose-like ribbons running through the slots along the sides of the car (those red-capped nodes with the divots along the body are where the ribbons would pass through).

But, here's the pics:

A close up of the cargo doors
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A close up of the livestock and people doors
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A view from above
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The crappy windows of which I spoke
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Full view on the X axis
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A closer view along the X

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Postby cshank4 » Sun Jul 31, 2005 12:14 am

The windows look fine for VS, espeically considering we'd probably not see them from too close. Overall though, good job, maybe dirty up the texture a wee bit to make it look like it goes through the atmosphere a lot.
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Postby tiny paintings » Sun Jul 31, 2005 3:54 am

Nice :)
Make a few windows dark and it'll look much better.
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Postby chuck_starchaser » Sun Jul 31, 2005 8:48 am

tiny paintings wrote:Nice :)
Make a few windows dark and it'll look much better.


Actually, the subtle light and dark pattern agrees with what's behind the windows: Not individual rooms but annular walking and sight-seeng areas. What I suggested to CoffeeBot is making the windows a bit bigger and rectangular, and to make the light inside whiter.

Just for the public record, I'm speechless about the job CoffeeBot's done. Not only did he seem to read my mind about details I left out in my original drawing, but he actually solved some engineering issues I had. And he must be "in the zone" or something: I stated in a note in my drawing that the outer casing also served as a heat-radiating surface for engine cooling. And did not specify material.
The obvious material I should have specified, barring "isometal" would have been titanium. And it so happens that when you heat up titanium in the presence of oxygen it forms thin layers of varius oxides, not just one; giving it a subtle "rainbow" appearance. Well, the "metal" pattern CoffeeBot created for texturing just happens to have that very look :) Almost chilling!
Not to speak of the sporty paint job, which makes the space elevator suddenly feel like the every-day occurrence it should feel like 1000 years from now; --just like we look at commercial airliners today and make nothing of it to the point of "caring" about the paintings on them as much as the plane itself. Wonder if an "spaceliner" logo might not be fitting as well, say "ALBATROSSpace" or whatever :D

Anyhow, maybe someone here with more knowledge of materials can answer this nagging question for me: "How fast can we go?"
The elevator car has a fusion engine, so energy is not the problem; but rather how fast rollers can spin.

The general issue is, for Earth, GEO is 43,000 km up; --bit longer than the distance around the equator (40,000 km). If we averaged Mach 10 (3.3 km/sec) 43,000/3.3=13,030sec=217minutes= 3.6 hours. Of course, in single player mode we can just compress the trip time and show a little movie, but time compression doesn't square up with multiplayer, in general, as CoffeBot pointed out to me. Not that there couldn't be fellow travellers to meet, magazines to read, or other things to do during the trip... ;-) But the question remains, how fast can we realistically go?

(By the way, the car would slow down to below mach speed before entering the atmosphere, we already decided; that's why the aerodynamic shrouds aren't there anymore; they were originally intended to allow supersonic penetration.)

My finger calculations are as follows:
If the rollers are, say, 1 meter in diameter, outer perimeter is 3.1415 meters.
Mach 10, or 3300 m/s divided by 3.1415 = 1050 revolutions per second = 63,000 RPM. Fighter jet engines I believe spin at like 100,000 RPM, and there the blades have to contend with hot exhaust as well as centrifugal force, so, seems to me it would be no rocket science to have this baby go at mach 20 even. But my question remains, can we go mach 50 or 100? "How fast can we go, realistically?"

EDIT:
One possible material for the rollers would be --again-- nanotubes, embedded in some epoxy, perhaps; would make the roller material so light and strong we might even be able to spin them at 1 million RPM and go Mach 150. In terms of acceleration, Mach 150 = 50,000 m/s. At 0.3 G it would take 4 hours and 40 minutes, so we are acceleration limited.
Okay, let's take it back to Mach 50:
330 m/s * 50 = 16,500 m/s
16,500 / 3.3 m/s^2 = 5000 seconds = 83.3 minutes = 1 hour, 23 minutes.
Distance travelled = 1/2 a t^2 = 0.5 * 3.3 * 25 * 10^6 = 41,250 km, so we'd better turn the equation around:
d = 1/2 a t^2 therefore t = sqrt( 2 * d / a ) where d is 43,000km/2, so,
half-time = sqrt( 2 * 0.5 * 43 * 10^6 / 3.3 ) = sqrt( 13M ) = 3600 seconds = 60 minutes = 1 hour accelerating to mid-point, another deccelerating to the finish.
I'd say this is our hard limit: 2 hours.

Why 1/3 of a G acceleration?
Because towards the end of the descent, decceleration is added to gravitational weight, and the cables would not be designed to take too much more weight than the car itself. Just economics: If you made the ribbons stronger, you'd probably want to send more cargo up or down, rather than increase the acceleration.

Finally, using the numbers above, maximum speed would be reached at mid point along the trip, and it would be equal to 3600 seconds times the acceleration of 3.3 m/s^2 = 12 km/s = 720 km/minute = 43,000 km/h ;-)
= Mach 36.4; and our 1 meter diameter rollers are spinning at 3820 revs per second, or 229,000 RPM.
Last edited by chuck_starchaser on Sun Jul 31, 2005 10:30 am, edited 1 time in total.
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Postby CoffeeBot » Sun Jul 31, 2005 10:25 am

chuck_starchaser wrote:...But the question remains, how fast can we realistically go?

(By the way, the car would slow down to below mach speed before entering the atmosphere, we already decided; that's why the aerodynamic shrouds aren't there anymore; they were originally intended to allow supersonic penetration.)

My finger calculations are as follows:
If the rollers are, say, 1 meter in diameter, outer perimeter is 3.1415 meters.
Mach 10, or 3300 m/s divided by 3.1415 = 1050 revolutions per second = 63,000 RPM. Fighter jet engines I believe spin at like 100,000 RPM, and there the blades have to contend with hot exhaust as well as centrifugal force, so, seems to me it would be no rocket science to have this baby go at mach 20 even. But my question remains, can we go mach 50 or 100? "How fast can we go, realistically?"


My thoughts would lie along the line of massive speeds in space, similar to starship travel, then slowing down to pass into the atmosphere (as chuck already stated), and then allowing gravity to pull the car the rest of the way. What would be this beastie's terminal velocity, how long would it take to reach it, and how hard would it be to stop it? But, then again, moving at those kinds of speeds would mean the passengers would most likely need to remain in harnesses, which isn't necessarily good.

Let's migrate this discussion back to the proper board, and keep this on topic about how we can improve the appearance of the car :)
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Postby chuck_starchaser » Sun Jul 31, 2005 10:44 am

True, I have sinned. But this little detour was actually relevant to the interior design of the car, when we get to it ...
Now we know that we'll spend the first hour of the trip down at 1/3 G, where Earth is "up", and the second hour of the trip at up to 1.3 G where Earth is "down"; which means we need sturdy sofas on the floors, and light chairs and tables on the ceilings, all permanently attached ;-)

Figures! This is even relevant to the exterior look! Maybe we should have a glass bottom, after all. During the first half of the trip, people would probably enjoy looking up to see Earth growing to twice its apparent size during that first hour...
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Postby CoffeeBot » Sun Jul 31, 2005 10:55 am

What if the human and livestock areas were built inside of a sphere, and placed on an axle? That way, no one would notice the sensation of the direction shift, and no one would be walking on the walls ;)

I think this would be similar to the "glass bottom" psychological effects. Could you honestly imagine being inside of a building with furniture on the floor and ceiling, not to mention the fact that the whole building seems to be turning upside down? I don't know about you, but it would drive me crazier than having nothing but glass below me :D
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Postby chuck_starchaser » Sun Jul 31, 2005 11:11 am

Myself, I'd find it exhilarating --can't wait to experience it in the game; and I hope I may convince you to do it as I just described: 2 sets of furniture.
Making the whole passenger area into a rotating structure would be an unconscionable expense and complication, unless, of course, some passengers are willing to pay double price for the fare... There could be special cars so designed.
Besides, if you notice in my original drawing, I have a shielded area for passage through the Van Allen belt, which I think is about mid-point, when the direction of gravity would be changing. So, passengers would move to this space, which could be low ceiling and have rotating chairs. By the time you're allowed to go back to the unshielded areas you'd be walking on the "floor side".
I'm not sure what the livestock will make of all this, though... :)
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Design Flaw?

Postby eddit » Sun Jul 31, 2005 2:55 pm

I don't mean to be critical, but I think that there's a design flaw with your elevator car. The key design issue is that you want to be able to remove vehicles from the elevator without disturbing the ribbon. So, either a) the whole vehicle spilts in half and clamps around the elevator cable, b) there's a slot halfway through the car where you can slide it on and off, or c) the ribbon attaches to the outside of the car.

The third option probably wouldn't be that great due the the stress you're going to put on the ribbon, unless you balanced it with another car on the other side.

What may ne a better design is an attachable trolly, which cars are attached to. You could even have four cars attaced to this to even the load.

Just my two cents
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Postby chuck_starchaser » Sun Jul 31, 2005 3:21 pm

You make a good point. The car, right now, cannot be detached from the ribbons for maintenance. I think the solution could be very simple, though: Just make the covers of the engines removable, and such that they come out with half the rollers, in one piece, or as the cover first, and the set of free-wheeling rollers second. Perhaps a seam on the texture around the engine covers is in order.
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Postby CoffeeBot » Sun Jul 31, 2005 10:03 pm

Heh. This is a big one that we missed. Even if the rollers opened so the ribbons could be removed, the car is too big to simply slide between two of them.

In some of the concept discussion, I think we mentioned that there would be ribbon slack at the asteroid end, and anchored planetside. A possible solution would be to use some sort of spindled anchor which allows the anchor point ribbons to be moved just enough to free the car. In other words, the objects on either end of the ribbons that dynamically adjust tension in the ribbons are vertically movable. The extension posts for the spindles would be located far enough away to allow the car to be trundled safely out. Or, make it simpler, and only move the base of two ribbons. This process can be done at either end of the track.

This also brings to mind certain safety features we haven't worked out. Sure, some high-powered energy weapons are mounted on the station to slag anyone that gets too close to the ribbons. But there are always freak accidents. What's saving lives, here?

Maybe we should start a "Space Elevator Safety Features" thread?
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Postby chuck_starchaser » Sun Jul 31, 2005 10:39 pm

Answers in reverse order:

The issue of safety is an ongoing discussion in the real world, and was discussed in this forum before your time. Basically: Freak accidents are possible but highly unlikely. Space is pretty big, and there are rules about where to fly, aren't there?... Well, there should be! :) And *intentional* damage to the cables is also very hard because the ribbons are hard to see in front of your face, let alone 100 kilometers off. And radar goes through them too. Bats might be able to find them in the atmosphere, but not in space. Also, nanotubes are SO strong it's hard to fathom. 100 or 200 times the strength of steel, and they are so light, and capable of stretching quite a bit. Basically, if a satellite hits a ribbon bang on, the ribbon might not even be damaged but just move with the satellite, gradually deccelerating it, until the satellite falls from its orbit. A ship getting a ribbon caught around a wing might be a different story.
In any case, one thing I was thinking we should have is propulsion jets at top and bottom, to correct the car's tilt, should one ribbon be lost or damaged, until the tension on the other ribbons can be rebalanced.

With regards to pulling the car off the ribbons, no sweat: The tension in the ribbons is in the order of dozens of tons, and parting them near either docking station would be pretty hard, but move a mile away, and you could push them apart by hand. I think the airline... er.. spaceline, would have a special vehicle to do this: A set of arms that push the ribbons apart, and another set of arms that grab the car from the end poles, then brings it back up to the station by using a bit of chemichal rocket fuel for propulsion.
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Postby cshank4 » Mon Aug 01, 2005 12:05 am

Hrm... safety... Man, back in my day, when our elevators crashed WE DIED. We didn't have your fancy, Emergancy Stop and Firefighter call buttons, we had TWO. Top Floor and Bend-Over-Kiss-Ass-and-Die button.


Seriously though.

I would think that in a COMPLETE emergancy that the car could be able to act as it's own station, cable get's busted it just gets to the end somehow... this would also help with maintenance, since you can do better stuff in Zero-G then in 1.0G.

I would definately put weaponry ON the car itself, point defense beams for taking out weaponry, flak for taking out fighets. Any ships bigger could probably be nailed by the Station's torpedo-bays.


Meh, just my ideas. Oh, with the cows and livestock and what not, just strap them down and sedate 'em.
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Postby chuck_starchaser » Mon Aug 01, 2005 1:18 am

Good point! MIGHTY good point!
Vegastrike is set at a time of war. And every time you leave from a base chances are 50% you get blown up in space (in my experience).
Why would anyone give a damn about "safety"?

R.e. Weaponry: Well, this is probably going to start another round of argument, but so be it! I'm up for it. The space elevator car has no need for weapons. Its weapon is acceleration. A mighty 0.3 G's that no ship can match. Now, you might say your llama can do 10 G's, but I say to you "Show me the technology that allows your llama to accelerate at 10 G's, and I'll put that technology in the car, and then it will accelerate at 70 G's". Fact is, having cables to push against, the car's engines are more efficiently utilized than any retro propulsion system you could ever muster. And if the powers that be at Vegastrike refuse to "show me the money", and insist on having "magical" engines capable of such accelerations, then I'll play magic against magic and just have the car keep ahead of any ship in its pursuit regardless of speed or acceleration.

And the same goes for landing on planets. Before you ask me "why take the elevator when I can land my ship in 2 minutes?", let me tell you no ship in the year 30,000,0000 ad will land on a planet in two minutes. It would take probably a couple of aerobraking passes to slow down enough for reentry, which is probably *days*, realistically; so if ships insist on being able to land in 2 minutes, I'll put a Dual Cam, Quad Warp, Hyperspatial Injection, Ultra-Turbo-SPEC engine on the car and have it reach the ground in 0.2 seconds flat.
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Postby smbarbour » Mon Aug 01, 2005 11:12 am

If it's on Earth and the car is below a certain point, it will easily pull 1g accelerations (just release the cable :)). Below that point the engines are actually reducing the acceleration.
I've stopped playing. I'm waiting for a new release.

I've kicked the MMO habit for now, but if I maintain enough money for an EVE-Online subscription, I'll be gone again.
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Postby smbarbour » Mon Aug 01, 2005 11:28 am

If it's on Earth and the car is below a certain point, it will easily pull 1g accelerations (just release the cable :)). Below that point the engines are actually reducing the acceleration.
I've stopped playing. I'm waiting for a new release.

I've kicked the MMO habit for now, but if I maintain enough money for an EVE-Online subscription, I'll be gone again.
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Postby CoffeeBot » Mon Aug 01, 2005 3:23 pm

chuck_starchaser wrote:...I'll put a Dual Cam, Quad Warp, Hyperspatial Injection, Ultra-Turbo-SPEC engine on the car and have it reach the ground in 0.2 seconds flat.


Can...can I get one of those for my plowshare? I promise I won't fly near the elevator. I, I won't even go NEAR other ships. I promise! Just run circles on the outer edges of the system. Honest! Please? Can I?
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Postby CoffeeBot » Mon Aug 01, 2005 3:29 pm

chuck_starchaser wrote:...I'll put a Dual Cam, Quad Warp, Hyperspatial Injection, Ultra-Turbo-SPEC engine on the car and have it reach the ground in 0.2 seconds flat.


Can...can I get one of those for my plowshare? I promise I won't fly near the elevator. I, I won't even go NEAR other ships. I promise! Just run circles on the outer edges of the system. Honest! Please? Can I?
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Postby chuck_starchaser » Thu Aug 04, 2005 10:24 am

Perhaps after you fly a few missions for me...
There is a corporation that produces key components that allow ships in Vegastrike to accelerate continuously at far beyond a reasonable fraction of a G. Besides technical knowhow, they count on the psychic powers one Voodoo/Black Magic sourcerer amongst their rank. His name is ******* and he flies a ******. I'll pay you 50,000 credits for ... ahem ... delivering a message...
:)
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Postby CubOfJudahsLion » Thu Aug 04, 2005 11:09 am

What's the orbital anchor gonna be like?
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Postby chuck_starchaser » Thu Aug 04, 2005 11:18 am

CubOfJudahsLion wrote:What's the orbital anchor gonna be like?


You mean the counterweight?, or the station? The counterweight will probably be an old and dusty asteroid. For a look at the station, check
this thread.
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Postby CubOfJudahsLion » Thu Aug 04, 2005 11:43 am

Nooooice. I couldn't post anything yesterday either, and I see you guys did not want to waste a second with this. I take it you dislike 'docking with the planet' as much as I do :D (if at least there was a trail of squares leading down instead of just one.) And since the elevator station is inherently a hub of commercial activity, things are bound to get interesting. Good luck with that.
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Postby chuck_starchaser » Thu Aug 04, 2005 12:15 pm

Thanks.
Yeah, now it's fast again; first time in probably 3 weeks. Wonder if there was a bug that got fixed. Let's hope it stays like this.
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