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[WIP][1.8.1, 1.9.1, 1.10.1] Principia—version Гельфанд, released 2020-11-15—n-Body and Extended Body Gravitation, axial tilt


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8 hours ago, R-T-B said:

Actually, Principia is pretty amazingly optimized as it stands.  It even multithreads when possible, I believe.

The issue is, the math it is trying to solve, known as the "n-body problem" has no closed form solution known to man.  Thus, it is inherently a slow and difficult simulation to run.  There isn't any answer known to modern science to make it cheaper than they have really.

So if you are having trouble running it I would advise either you upgrade, or don't run it.  Don't expect miracles sadly.

Thank you. I tried. 4GB works.

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On 9/17/2020 at 3:48 PM, eggrobin said:

For the new moon (lunation number 256), the new release (Gateaux) is out.

  • Support for 1.10.1 has been added. Note that the behaviour of Principia in the presence of comets is hard to test; users who encounter problems when comets are present are invited to report bugs.

See the change log for more details.

For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.

yes!!!!!! 

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  • 3 weeks later...

I am having a problem with RSS and Principia. I uninstalled RSS and Principia worked fine, but as soon as I install RSS the game crashes if I try to create or load a game.

This is what I found in the log...

Log file created at: 2020/10/08 20:03:29
Running on machine: DESKTOP-GLNTJ9D
Log line format: [IWEF]mmdd hh:mm:ss.uuuuuu threadid file:line] msg
    @   00007FF90DAD6360      google::LogMessageFatal::~LogMessageFatal [0x00007FF90DAD635F+47]
    @   00007FF8DECB5754      principia__VesselVelocity [0x00007FF8DECB5753+310387]
    @   00007FF8DED9013F      principia__VesselVelocity [0x00007FF8DED9013E+1205854]
    @   00007FF8DEC3E9A0      principia__UpdateCelestialHierarchy [0x00007FF8DEC3E99F+383]
    @   000001F1EF2BD3E6      (No symbol) [0x000001F1EF2BD3E5]
F1008 20:03:29.855654  7504 map_util.hpp:58] Check failed: it != collection.end() Map key not found: 31

 

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5 hours ago, taiwanluthiers said:

I am having a problem with RSS and Principia. I uninstalled RSS and Principia worked fine, but as soon as I install RSS the game crashes if I try to create or load a game.

FWIW, tracked in #2757.

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Ok, I got a question now...

Before Principia I can choose a target and then base my maneuver around this, but now that's not possible.

So I would have to make burns prograde, retrograde, normal, etc. and hope the pink line will intersect my target. This wastes fuel like crazy. And since I can't point the SAS at target anymore I have no idea how to get close to target, let alone dock with it.

Worse problem is doing Trans Lunar Injection. Now I got close to the moon but no way I can ever actually orbit around a moon or whatever.

MechJeb doesn't work because you can't target anything anymore.

So how am I supposed to dock with anything or make interplanetary transfers?

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18 hours ago, taiwanluthiers said:

Ok, I got a question now...

Before Principia I can choose a target and then base my maneuver around this, but now that's not possible.

So I would have to make burns prograde, retrograde, normal, etc. and hope the pink line will intersect my target. This wastes fuel like crazy. And since I can't point the SAS at target anymore I have no idea how to get close to target, let alone dock with it.

Worse problem is doing Trans Lunar Injection. Now I got close to the moon but no way I can ever actually orbit around a moon or whatever.

MechJeb doesn't work because you can't target anything anymore.

So how am I supposed to dock with anything or make interplanetary transfers?

You can select the reference frame, that is to say the body that your trajectory is projected around, in a menu option of a similar name. Trans-lunar injections are best done in the fourth option of that menu (with the Moon selected), which draws the orbits in relation to an imaginary Earth-Moon line. If you have a maneuver in the flight plan, you can simply move it around a bit until the trajectory lines up with the Moon. From there is basically the same as stock KSP - execute the maneuver, (go into the inertial Moon reference frame), wait and then perform the capture. Intersecting another vessel essentially the same, Principia offers a frame relative to your target vessel.

In general, the documentation for Principia is a good place to start. It provides explanations and examples, including a Mun transfer to help explain the basics of how to play with the mod.

Edited by Delay
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Update on inter-body transfers with Principia.

Mechjeb can work, but you have to watch it. It helps by allowing you to automate some of the more mundane stuff (like playing guessing games with which way to go!). But you use the feature to allow you to target planets, you can use Mechjeb as usual but you must fine tune it

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For the new moon (lunation number 257), the new release (Gauss) is out.

  • A bug that would occasionally lead to crashes when parts exploded has been fixed (#2716).

See the change log for more details.

For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.

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  • 2 weeks later...

Not sure if this is the correct place to ask, but is kOS (v1.2.1.0) compatible with Principia?  I have been having problems with maneuver node execution in my RP-1/RO playthrough.  I can list full set of mods, game version, etc. if that will be helpful.

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kOS and Principia don't do anything special for each other. So they are as compatible with each other as any two random mods are.

On 10/28/2020 at 9:04 PM, golfsoccer9 said:

I have been having problems with maneuver node execution in my RP-1/RO playthrough.

You will need to be more specific than that to get help. What kind of problems?

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I'm currently testing long-term stability of my system in Principia after preliminary success in US2, and I'm getting spammed with "apocalypse occured" errors, all on the exact same body, which hasn't deviated from its orbit at all in at least 1700 years. The first error occurs only a couple months in, and there seems to be a little over one a year. 

What exactly does this mean? Is it just a side effect of running at a very high timestep with a GPU and CPU that aren't really all that great?

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[Note: this was clarified over Discord; answering the questions asked here for posterity]

6 hours ago, WarriorSabe said:

I'm currently testing long-term stability of my system in Principia after preliminary success in US2, and I'm getting spammed with "apocalypse occured" errors, all on the exact same body, which hasn't deviated from its orbit at all in at least 1700 years. The first error occurs only a couple months in, and there seems to be a little over one a year. 

What exactly does this mean?

Your system is either unstable, or doing things too quickly for the default integration settings (« unstable » is just a special case of that, where close encounters happen too quickly; Principia doesn’t (yet) care about orbits nor whether things remain on them). US2 tends to be an unreliable predictor of what happens to a solar system with Principia (probably because of different conventions for the representation of the initial state, possibly of its choice of numerical methods and timesteps ).

Quote

Is it just a side effect of running at a very high timestep

Time warp does not affect the time step used by the integrator (this is why max time warp can be slow with Principia).

Quote

with a GPU and CPU that aren't really all that great?

Nor do your system settings matter for anything but performance.

You may want to look at https://github.com/mockingbirdnest/Principia/wiki/Principia-configuration-files#the-principia_numerics_blueprint-configuration and https://github.com/mockingbirdnest/Principia/wiki/Principia-configuration-files#annex-choosing-a-fixed-step-size-integrator.

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On 11/6/2020 at 3:45 AM, septemberWaves said:

Since stock-like "spheres of influence" aren't a thing with Principia, how are altitudes determined for high/low space science over a celestial body, and where are the limits set?

The stock spheres of influence do exist even with Principia, Principia just doesn't care about them. The stock science system uses those same SOIs for determining which experiments are available. In case of other planet packs, those limits are set by the respective planet packs, Principia doesn't meddle with it.

And anyway - with or without Principia - altitudes don't depend on the SOIs at all. Altitude is simply (distance from body center minus body radius). Conceptually, an altitude with respect to Mun still exists even if you're in the SOI of Jool.

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  • eggrobin changed the title to [WIP][1.8.1, 1.9.1, 1.10.1] Principia—version Гельфанд, released 2020-11-15—n-Body and Extended Body Gravitation, axial tilt

For the new moon (lunation number 258), the new release (Гельфанд) is out.

Performance of operations based on iteration over trajectories has been improved thanks to a contribution from @rnlahaye.

See the change log for more details.

For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.

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These are initial state files for use with RealSolarSystem https://drive.google.com/drive/folders/1iNlip4K66oaOQgPm7nDnpQxExuDmp6lu

Some people like to play or simply want to explore RSS in more recent years, rather than 1951 with which Principia starts by default. And of course you can timewarp to whatever year you want to. But until the devs complete their work on #2400 and related issues, it is going to remain a bit painful the further from 1951 you timewarp. The folder linked above contains initial states every 5 years from 1950 to 2020. So the initial state file for 2010 gives you a game that starts on 2011-01-01T00:00:00 UTC. Replace the initial state file in the Principia/real_solar_system folder with the one you want. Keep in mind that this will only have effect on new saves, an existing save won't magically timewarp into the future or past because you changed that file.

@eggrobin has done a cursory verification of the initial state files. But if you run into any inaccuracies, that's my responsibility, not his or @pleroy's.

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On 11/20/2020 at 1:47 AM, scimas said:

Some people like to play or simply want to explore RSS in more recent years, rather than 1951 with which Principia starts by default.

@scimas Thank you very much for sharing all that work!   Just tried your 2015 .cfg...I pulled a few vectors from jpl horizons to spot check your numbers, loaded it in KSP 1.9.1 & took a few screenshots of astronomical events...looks great!

with scimas' 2015 initial state vectors .cfg (KSP 1.9.1)
tLld4bL.png
Le8IcQe.jpg
8MWBBfj.jpg

 

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1 hour ago, AloE said:

... a few screenshots of astronomical events...

It's always eminently satisfying to see that Principia correctly simulates astronomical events.

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