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Old 11-17-2017, 03:41 PM   #1
kreios
 
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Default [Blog] n-Body Politics

https://nbodypolitics.gitlab.io/

Finally starting a blog on the setting I had in mind for some time. I will also include corresponding rules, examples, and thoughts on GURPS rules related to sci-fi.

Starting with the first post:

Quote:
Originally Posted by https://nbodypolitics.gitlab.io/2017/11/17/introduction.html
For quite some time, I have worked on/thought about/written some things down on a setting I have preliminarily called n-Body Politics. Themes and ideas have changed over the last years, but the basics have remained the same - itís supposed to be a fairly hard science-fiction setting concentrating on themes of politics, humans, and space.

For inspiration, look at Transhuman Space, the Expanse, or 2300 AD - this is not Star Warís slow spaceships and fighters. Itís Newtonian movement (Einsteinian movement will probably not be attained), space combat with kinetics and lasers, and most crucially without energy shields.

But itís not supposed to be about war (though the technology and military positions shape arguably do shape the world) - itís about the people living in it. And yes, itís also about conflicts on a state/nation level.
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Old 11-18-2017, 04:33 AM   #2
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Default Re: [Blog] n-Body Politics

/me warily wonders if the politics will be optimistic like THS, or follow the lead of grim darkness of the Expanse . . .
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Old 11-18-2017, 07:54 AM   #3
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Default Re: [Blog] n-Body Politics

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Originally Posted by vicky_molokh View Post
/me warily wonders if the politics will be optimistic like THS, or follow the lead of grim darkness of the Expanse . . .
I'm actually not sure whether the Expanse is that much darker than THS.

No, wait, hear me out!

Spoilers follow, but I'm trying to mark at least those for the later books.

I'd argue that much of the Expanse's less optimistic parts stem from the two factors of essentially only having a bipolar world and weapon yields. Note that I'm only looking at the Protomolecule as a generic catalyst of tension; the same might have been achieved by new technology.

Now, much of the tension comes from the fact that there are essentially only two main factions (Earth and Mars) plus the Third-World-equivalent (the Belt). This means that your conflicts are immediately much bigger, and escalation (coupled with the high weapon yields) much more dangerous.

However, I'd argue that THS, were it a bipolar world, could easily see something like that. The Pacific War can be compared to any of the Earth/Mars conflicts in the Expanse, except it actually went hot even on Earth. It just wasn't as destructive because the two factions didn't cover half a globe. Or look at the Andes War.

We also, in THS, tend to concentrate on the fifth-wave nations and on space (which has to have a high TL). The Expanse, on the other hand, looks at the proverbial underbelly of the system. What do you know about Earth? That there are 30 billion people who, according to Martian propaganda, consume free drugs and get a basic income. That suggests an acceptably high planetary income, but we almost never visit those places.

Spoiler for Nemesis Games
Spoiler:  


In summary, I'd actually say that the differences come more from a concentration on the poorer areas, only two main powers, and a higher "vulnerability" of the whole setting and situation - a necessity if you want to have those high-stakes stories. THS is still more optimistic, though.

But don't worry, I plan to be inspired much more by THS.
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Old 11-18-2017, 12:40 PM   #4
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Default Re: [Blog] n-Body Politics

Quote:
Originally Posted by vicky_molokh View Post
... grim darkness of the Expanse . . .
In the grim darkness of the Expanse there is only Protomolecule!
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Old 11-22-2017, 12:47 PM   #5
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Default Re: [Blog] n-Body Politics

Quote:
Originally Posted by https://nbodypolitics.gitlab.io/2017/11/22/ftl_travel.html
Having done the introduction, the next logical step is to look at how the setting differs from today. And the main difference is - quite obviously - space. In itself, we can look at space technology in three different perspectives: Faster-than-light travel, STL travel and interface (or surface-to-orbit) travel. Weíll start with the FTL travel.

One might argue that one of the main setting decisions is which FTL drive to use. We need an FTL drive to get to other planets (the Space in our Space Opera) - and any restriction and attribute of the FTL drive shapes our setting.
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Old 11-22-2017, 05:44 PM   #6
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Default Re: [Blog] n-Body Politics

--Thoughts on FTL system--

Overall, your hyperdrive looks good. I'm confused, though. What is the range on your FTL drive? Or have you not come up with a specific number yet?

Note that your FTL design hasn't eliminated the potential for c-fractional (i.e. relativistic) projectiles. If you can drop out of hyperspace around asteroids, what is stopping you from dropping out at an asteroid in interstellar space? That would give you enough range to reach c-fractional velocity if you have a reactionless drive. If you're going to include reactionless STL drives, preventing this kind of abuse requires the FTL drive to be limited to the main part of a system or have sensors capable of detecting ships traveling at FTL at interstellar ranges.

Having the exclusion zone scale with mass seems more plausible than it scaling with diameter. That is a little more cumbersome than just using the diameter of the object. But on par with the math you would need to use the reaction drives from Spaceships.

However, I find it hard to believe that the arrival zone has a hard boundary. I'd allow daring captains to jump in closer. But I can't figure out an astrogation penalty scheme that is light enough to make this plausible without making it so easy that everyone would risk it to cut right to the recharge zone. So never mind.

Speaking of which, what is being recharged at these pit stops?

--Other Thoughts--

Does FTL communication exist in this setting? Or is communication limited to ship speeds?
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Old 11-23-2017, 11:29 AM   #7
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Default Re: [Blog] n-Body Politics

Quote:
Originally Posted by Emerald Cat View Post
--Thoughts on FTL system--

Overall, your hyperdrive looks good. I'm confused, though. What is the range on your FTL drive? Or have you not come up with a specific number yet?
Both, actually: The FTL drive has a certain range defined (1/5th of the distance between habitable planets, and about one jump per unimportant system), but not in LY yet. If we take the average density of stars near Earth, then the range is about 6-8 LY.

Quote:
Note that your FTL design hasn't eliminated the potential for c-fractional (i.e. relativistic) projectiles. If you can drop out of hyperspace around asteroids, what is stopping you from dropping out at an asteroid in interstellar space? That would give you enough range to reach c-fractional velocity if you have a reactionless drive. If you're going to include reactionless STL drives, preventing this kind of abuse requires the FTL drive to be limited to the main part of a system or have sensors capable of detecting ships traveling at FTL at interstellar ranges.
Very good point. It does at least make acceleration-FTL-undetected annihilation impossible. But, spoilers, I'll not take reactionless drives.

Quote:
However, I find it hard to believe that the arrival zone has a hard boundary. I'd allow daring captains to jump in closer. But I can't figure out an astrogation penalty scheme that is light enough to make this plausible without making it so easy that everyone would risk it to cut right to the recharge zone. So never mind.
Actually, this is an interesting idea. I had an idea about the recharge limit as a more flexible boundary (which roughly scales like a sigmoid function, meaning you don't have to get closer to the main star if you're willing to wait for a few weeks). I'll keep it in mind for a revision.

Quote:
Speaking of which, what is being recharged at these pit stops?
Space Magic. Maybe the FTL core is starting to get decoherent during jumps and needs gravity to regenerate. I'll have to think about an in-universe reason.

Quote:
--Other Thoughts--

Does FTL communication exist in this setting? Or is communication limited to ship speeds?
I don't think it will, and neither will FTL sensors. However, I'll decide in the future.

Also, thank you for the interest!
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Old 11-24-2017, 12:05 PM   #8
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Default Re: [Blog] n-Body Politics

They start at rest with regards to the object? Ok, that took guts to go for. It also means that if your STL light drives fails, you face certain death after a FTL jump.

5 kps is a huge delta-V cost, particularly if you make it apply both ways. with 10 kps I can get into orbit from earth's surface. And I can't just use an efficient Ion drive, because I'll slam into the earth first. So it looks like I'm going to have to spend large parts of my ship either storing fuel or massing three rocket engines to get the acceleration I need. Its not as bad as planetary take-off, fortunately, because falling is an option, and because you don't need to accelerate quite as fast, but it still places restricting demands on the drives.

So I wanted to know how different sizes of planet act with these rules, and what minimal spacecraft engines look like. And you made me spend an hour doing math. Hopefully some of it will be useful to you:

if you don't use engines after appearing around earth, you have a little less than 8 hours before you impact. using 1.11 * (R^3/(GM))^.5 gives the time to the center of the body. I figured the actual numbers, but those equations are nasty, and this gives pretty good results.

Resting time to impact simplifies down to about 35 * (GM)^.25 if you use .1 newtons instead of .01G

Engines need to be .015 G's or greater in order to make orbital velocity before the powered crash time is up. This is constant regardless of the body you are orbiting. the actual minimum is something else, but it lower, depends on the mass and radius of the orbiting body, and this is probably a good rule of thumb. It's also interesting, because a lot of rocket engines play just above or just below this values.

The KPS for the resting orbit of a body is (GM)^.25

the resting orbit for a body is (GM)^.5

* I am sorry for liberally mixing earth gravity with the gravitational constant, both represented by G. If the G has an M next to it, its the gravitational constant.

On minimally viable objects, all the planets have a recharge zone, the Galileans and Titan have recharge zones, but Pluto and Ceres do not, reinforcing the categorization of them as dwarf planets. Earth's moon does have a recharge zone, and in fact bodes like it take less fuel to use as stopping places. The cheapest place to stop in the solar system is Europa, but the next is earth's moon, both being about of third of what you'd spend to land on earth. There are probably some kuiper belt objects that can be used as rechargers, but we haven't found any in the solar system, which means they may very well be secrets well guarded by militaries, guilds, and smugglers. Or valuable waypoints through gaps in a network.

You CAN use a star directly, but you'll want really big fuel tanks to pull that off. A minimal red dwarf requires 50 kps to stabilize, and twice that if you ever want to leave. The sun requires 107 kps to stabilize. I think the minimum vessel I'd try jumping to a star would have 3 Advanced pulsed fusion drives, 2 fusion engines, and 11 tanks of fuel at TL9. The remaining fifth of the ship is probably shielding, control, life support, and living quarters for the nuts trying this out. And two weeks worth of food.
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Old 11-26-2017, 06:39 AM   #9
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Default Re: [Blog] n-Body Politics

Quote:
Originally Posted by ericthered View Post
They start at rest with regards to the object? Ok, that took guts to go for. It also means that if your STL light drives fails, you face certain death after a FTL jump.
It's actually not that different from any other method: If your main drive fails, you'll either crash into something or will be on a month-long journey for which your supplies probably won't hold. (Excepting things like a free return trajectory).

Quote:
5 kps is a huge delta-V cost, particularly if you make it apply both ways. with 10 kps I can get into orbit from earth's surface. And I can't just use an efficient Ion drive, because I'll slam into the earth first. So it looks like I'm going to have to spend large parts of my ship either storing fuel or massing three rocket engines to get the acceleration I need. Its not as bad as planetary take-off, fortunately, because falling is an option, and because you don't need to accelerate quite as fast, but it still places restricting demands on the drives.
Agreed, and this is something we'll see in the next post.

Quote:
if you don't use engines after appearing around earth, you have a little less than 8 hours before you impact. using 1.11 * (R^3/(GM))^.5 gives the time to the center of the body. I figured the actual numbers, but those equations are nasty, and this gives pretty good results.

Resting time to impact simplifies down to about 35 * (GM)^.25 if you use .1 newtons instead of .01G

Engines need to be .015 G's or greater in order to make orbital velocity before the powered crash time is up. This is constant regardless of the body you are orbiting. the actual minimum is something else, but it lower, depends on the mass and radius of the orbiting body, and this is probably a good rule of thumb. It's also interesting, because a lot of rocket engines play just above or just below this values.
Quite interesting, and I didn't actually compute that myself - I had just assumed that a sufficiently strong engine (which I've already defined) would be available. I'll definitely have to spend another post later on on a few more options and math.

Quote:
On minimally viable objects, all the planets have a recharge zone, the Galileans and Titan have recharge zones, but Pluto and Ceres do not, reinforcing the categorization of them as dwarf planets. Earth's moon does have a recharge zone, and in fact bodes like it take less fuel to use as stopping places. The cheapest place to stop in the solar system is Europa, but the next is earth's moon, both being about of third of what you'd spend to land on earth. There are probably some kuiper belt objects that can be used as rechargers, but we haven't found any in the solar system, which means they may very well be secrets well guarded by militaries, guilds, and smugglers. Or valuable waypoints through gaps in a network.
Also very interesting. My assumption is that the range is sufficiently high that there's almost always going to be a few stars in range, and that brown dwarfs would be too inefficient to stop at for a commercial route.
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Old 11-27-2017, 09:15 AM   #10
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Default Re: [Blog] n-Body Politics

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Originally Posted by ericthered View Post
You CAN use a star directly, but you'll want really big fuel tanks to pull that off. A minimal red dwarf requires 50 kps to stabilize, and twice that if you ever want to leave. The sun requires 107 kps to stabilize. I think the minimum vessel I'd try jumping to a star would have 3 Advanced pulsed fusion drives, 2 fusion engines, and 11 tanks of fuel at TL9. The remaining fifth of the ship is probably shielding, control, life support, and living quarters for the nuts trying this out. And two weeks worth of food.
I just realized what this ship is: its a surveyor. Detecting planets around stars from light years away is something of a hit and miss proposition that takes big equipment and a ton of analysis. If you're in the system, it becomes much easier. So you send a ship to the next star you need mapped, it maps everything, and you can extend your charts with only a week or two of effort. You need to stay for about that amount of time to calculate the orbits of the moons in sol system anyway, unless you have really good gear (which is heavy, and you probably have to stay that long anyways).

Unless there is a way to fire the FTL twice in quick succession. Then that might become the best way to do surveys.

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Originally Posted by kreios View Post
Also very interesting. My assumption is that the range is sufficiently high that there's almost always going to be a few stars in range, and that brown dwarfs would be too inefficient to stop at for a commercial route.
Brown dwarfs are a pretty expensive option, yeah. Its actually shorter to use the moon 10 times than to use jupiter once. I wasn't thinking of brown dwarves. I was thinking of some Icy body like Pluto or Eris orbiting a star at long distance. Eris is within 20% gravity of letting you recharge your drive. Such a body is going to be hard to find and cheap to travel to: great for smugglers, pirates, and military forces.
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