eggrobin

[WIP][1.5.1, 1.6.1, 1.7.x] Principia—version פרנקל, released 2019-11-26—n-Body and Extended Body Gravitation, axial tilt

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I'm just saying, maybe a wild guess/downscale from RSS might be better than not having any gravitational quadrupoles in the Kerbol system at all.

It would, but it's somebody else's problem. :)

Nope :P. You've spent so much time doing gravity stuff in inertial reference systems that you totally forgot about the rules that apply on the surface of rotating bodies (no offense :)). Kerbin should be oblate because it's rotating, but it is not because SQUAD simplified things. In real-life, if Earth was suddenly spherical, all oceans would flow towards the equator until Earth has returned to its proper oblate shape. This effect can be measured in-game, because the centrifugal force is simulated properly by the engine. At 45 deg N on a sphere it has equal upwards and southwards components, so the effective gravity vector is not perpendicular to the surface.

Ah, on the surface, yes. :)

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gimme gimme gimme, where can i ger this!

- - - Updated - - -

I do offer the mod as a download, just go on the IRC channel and ask for it. :)

You're probably asking why I don't simply put the link on the forum though.

Well, this:

In particular, there are some atypical considerations (bugreporting is different than for other mods, we have our own logs and our main failure mode is crashing, you need different builds for different platforms, you need to have the proper C++ runtime for your build).

More generally, I'm afraid of this place turning into the FAR or MechJeb thread while this mod is under heavy development; I'd rather spend my time writing the mod than managing a messy forum thread, especially since it tends to take me a while to write a post (this one took me 25 min).

Drag is mentioned in the OP, in the "Further modding" section, however it will be a while before we add that. When using RSS with Bourbaki, you already get interesting precession of low or medium Earth orbits due to oblateness, which requires you to either correct every now and then, or to pick stable orbits (üþûýøѠorbits are fun!).

Edit:

Oh, I had entirely forgotten this "prototype useless for gaming purposes" thing. I wrote that back in the days of the C# prototype in February 2014, that plugin ignored thrust (and was ridiculously slow)...

I should probably remove that, considering I always play with principia. :P

where and how can i log on to IRC

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Are there any tutorials to put a probe in L1?

EDIT: Or is there any way to put a probe in a Kerbol-Synchronous orbit?

Edited by nicogusuarez
Kerbol not sun

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Yes, but funniness may happen as you progress through time and your new planets start to affect the existing planets. Also, the new planets may not actually be in realistic orbits to begin with, so you may find them rapidly falling out of place. But that's because it works with mods that add planets. :)

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Are there any tutorials to put a probe in L1?

EDIT: Or is there any way to put a probe in a Kerbol-Synchronous orbit?

Kerbol-synchronous orbits are not currently possible as I understand it because of no J2 moments for the Kerbin system. For RSS and sun-synchronous orbits around Earth, you have this: https://en.wikipedia.org/wiki/Sun-synchronous_orbit with a formula for the inclination with a given semi-major axis. For L1, I suggest playing around in cis-lunar or cis-munar space for a while with a ship that has lots of fuel available as you build intuition. Beyond the lagrange points, distant retrograde orbits are also fun to play with.

I have a question myself: since planetary orbits are integrated just like spacecraft orbits, is it possible to move small moons around with a big enough ship?

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I have a question myself: since planetary orbits are integrated just like spacecraft orbits, is it possible to move small moons around with a big enough ship?

I think the answer is in the FAQ:

Do you simulate the gravity of player-created vessels and asteroids?

I'll let ferram4 answer that one.

Umm... Yes, actually! It's only a few μm/s2 from most vessels, but we do simulate it. Really. It actually doesn't cost any overhead at all!

On a more serious note, no. And we will not.

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Although, applying sufficiently ridiculous amounts of thrust to a planetoid should change its orbit. It would be so tiny a change as to beggar the imagination, but you could. Theoretically, at least. Because nothing is on rails.

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Although, applying sufficiently ridiculous amounts of thrust to a planetoid should change its orbit. It would be so tiny a change as to beggar the imagination, but you could. Theoretically, at least. Because nothing is on rails.

A re-enactment of Scott Manley's attempt to deorbit the Mun would be very amusing to replicate :)

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Kerbol-synchronous orbits are not currently possible as I understand it because of no J2 moments for the Kerbin system. For RSS and sun-synchronous orbits around Earth, you have this: https://en.wikipedia.org/wiki/Sun-synchronous_orbit with a formula for the inclination with a given semi-major axis. For L1, I suggest playing around in cis-lunar or cis-munar space for a while with a ship that has lots of fuel available as you build intuition. Beyond the lagrange points, distant retrograde orbits are also fun to play with.

I have a question myself: since planetary orbits are integrated just like spacecraft orbits, is it possible to move small moons around with a big enough ship?

Okay, thanks. Ill try to fool around with Lagrange points in the Kerbin-Mun system!

Will post pics if succeeded.

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A re-enactment of Scott Manley's attempt to deorbit the Mun would be very amusing to replicate :)

Someone strap a few orion drives to the mun and do this.

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Someone strap a few orion drives to the mun and do this.

please someone do this and post a video. or ask the great scott (pun absolutely, shamelessly, intended) himself to try!

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Although, applying sufficiently ridiculous amounts of thrust to a planetoid should change its orbit. It would be so tiny a change as to beggar the imagination, but you could. Theoretically, at least. Because nothing is on rails.
A re-enactment of Scott Manley's attempt to deorbit the Mun would be very amusing to replicate :)
Someone strap a few orion drives to the mun and do this.
please someone do this and post a video. or ask the great scott (pun absolutely, shamelessly, intended) himself to try!

Thrusting does not move planets (it doesn't in stock, and we just grab the change in velocity from what the stock game does). Even if we handled thrust ourselves, it would be significantly more convenient to ignore the effects of thrust on celestials: their orbits are (since Bourbaki) precomputed by the Ephemeris class, allowing us to use a larger timestep for that, as well as compute it only once. Ephemeris then provides functions to integrate the trajectories of massless bodies within the system (optionally with some proper acceleration), and that is what we use for vessels (stock's asteroids are vessels too).

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Thrusting does not move planets (it doesn't in stock, and we just grab the change in velocity from what the stock game does). Even if we handled thrust ourselves, it would be significantly more convenient to ignore the effects of thrust on celestials: their orbits are (since Bourbaki) precomputed by the Ephemeris class, allowing us to use a larger timestep for that, as well as compute it only once. Ephemeris then provides functions to integrate the trajectories of massless bodies within the system (optionally with some proper acceleration), and that is what we use for vessels (stock's asteroids are vessels too).

Oh well, would have been a fun thing to do.

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Oh well, would have been a fun thing to do.

Fortunately, there is a steady supply of fun things to do (although they will be far more accessible once we get manœuvre nodes working). :)

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[quote name='eggrobin'](although they will be far more accessible once we get manœuvre nodes working). :)[/QUOTE]

Please say that will be available soon.

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Wow, I am surprised. I came here to ask if heliosynchronous orbits are possible (well, precession of orbits due to ellipsoidal shape of bodies really) is possible and if you would consider it for implementation.. and it is already in by looking at your last change-log! I am blown away by that to be honest! I never really understood these orbits, they seem like wizardry. I am very much looking forwards to your mod!

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The physics are super jumpy when landing on bodies, i landed on minimus, and well, Jeb ,bill and bob don't have a ship anymore, it seems like the rocket is acting like its hitting minimus at orbital speeds, even though i was only going 1.2 m/s , i don't mean that its exploding, its sort-of , rubber-like, its very springy like when a part is scraping the ground, or a broken rover wheel, except im only touching the ground, oh and the kerbals get KO'd when i touch the ground, other than that, this mod is a work of beauty i love messing with it too! great job, your a true physicist.

On 11/18/2015 at 3:47 PM, jkortech said:

Does this work in KSP 1.0.5?

yes it does, im testing it currently

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1 hour ago, Mods_o_joy said:

So, has anyone made a video or something because i have No F^#& Idea what this is other than the fact that it changes physics(COME AT ME KRAKEN!)

Short explanation: It changes the way orbits are calculated. It does away with spheres of influence as hard-shell balls around objects in space inside which only the dominant object has sway, but rather, as in real life, models gravity as a combination of forces applied by all nearby objects (i.e. if you're halfway between Kerbin and Mün - or Earth and the Moon - expect both to pull at you, and your orbit to shift accordingly). As such, orbits that are stable over time become harder (so you'll need to do stationkeeping), but things like Lissajous orbits (around Lagrange points) and suchlike become possible, opening new doors in the game.

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On 3.2.2016 at 11:53 AM, Mods_o_joy said:

So, Real life physics?, How much will this Kill my FPS, Drop from 20 normal down to 1 is what im expecting

 

Didn't drop the framerate for me.

As long as I didn't activate the 3D "orbital lines" (Haven't played in a while. Can't remember how they are named. But the 2D versions worked without dropping the framerate).

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@eggrobin Is this the mod that repeatedly destroyed the Joolian system? Damn Tylo...

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