Kerbal Space Program - Principia - Doing Gravity Properly
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- Опубліковано 27 сер 2024
- Kerbal Space Program uses only single gravitating bodies in its physics model this is a pretty good approximation for most things, but for those that want more realism there's Principia.
forum.kerbalspa...
Jesus. I vastly underestimated how much KSP simplifies orbital mechanics.
Here I was all proud of learning real space sciences.
+Edouard Dubois Don't worry, Whilst KSP does neglect full n-body physics. Patched conics predictions (how KSP does orbits) are really used in actual human spaceflight. Depending on the mission ofcourse.
So don't worry, although simplified, you're still learning real space sciences :)
+Edouard Dubois
Don't feel too bad. We flew Apollo to the Moon on KSP-style one-body patched conic orbits, and Earth-Moon space is where multi-body physics matters more than anywhere in the Solar System.
You actually learned real space science. You just haven't learned *all* of it.
Also, I think the way KSP scales down all its bodies and distances but them makes them very dense so the gravity works means the multi-body corrections are bigger. In the real solar system, things don't wobble around nearly that much.
Eldritch
Hmm. So we need Real-Scale Solar System + Principa
*cracks whip
Mod makers! Quickly, to work!
+Eldritch Oh man you made me feel way better, that time lapse at the end of the vid totally looked unrealistic and nearly destroyed my world view, if it was really like that then we'd surely have no moons around any body in our solar system...
As he said, it's because the patched conics visual lines were calculated *relative to Jool* and not *relative to the Jool-system's Barycenter*. In real life, if you viewed something like the Jupiter system with patched conics predictions relative to Jupiter itself, and not it's barycenter, you'd see similar wobbling (Just not has profuse).
Ok, since we got that, now it's time for non-spherical gravity fields. Sun-synchronous orbits, unstabe low moon orbits and all that. Oh and also high atmospheres, solar radiation pressure and relativistic effects. Let's go crazy!
+Anton Gromov Yep, non spherical gravity fields are possible in the RSS version.
+Anton Gromov Yeeeaah... My CPU is barely keeping up alreay.
My poor AMD FX6300 will die if that happens :P
+Anton Gromov I'm all in for Radiation pressure. let us make real solar sails!
+Scott Manley RSS version?
The real question is...
CAN YOU DE-ORBIT A MOON NOW???
Yep, tylo kicks another moon around Duna (correct me if I got the wrong planet) out to deep space, and currently crashes the game :( luckily, that takes a "while" so not a major problem!
+Damien W I remember now, Jool not Duna
+Damien W That's pretty cool
YES
oh man, I want to see it happen! I will absolutely try
So Lagrange points are now a thing?
+SkulShurtugalTCG Well, he did mention it ;)
Now see, this? This is what people need see to understand why Rocket Science is a euphemism for "something very difficult". I have to adjust my communication satellites orbits occasionally with single-body physics just because of floating point errors. If I have to worry about Mun or Jool knocking the orbits about... I'd need computers aboard the satellites that can run in the background while fast-forwarding to perform station keeping maneuvers.
And a supercomputer to handle all the calculations.
And Rich Purnell to find the courses.
+1 for astronaut saving
Rich Purnell manuever best manuever
Rich Prunell is a steely eyed missile man.
kOS does not run on ships that don't have current focus, so no it can't handle background n body stationkeeping.
haha martian reference go brrrt
Great, now ksp actually needs a supercomputer to run on.
+PhazonSouffle I just learnt that KSP does not support multithreading. Sad times.
+Energy Core KSP supports multi threading, but the CPU use is dominated by Unity's physics engine which is single threaded.
Yeah, i've been reading up on the matter for the last half hour. It's really a shame because it kicks hardware scalability out of the game. I hear Unity uses PhysX, so maybe a GPU with a suitable architecture can accelerate the processing?
I really hope the game will be able to handle huge couple thousand part ships at 60FPS in the future. Cheers.
The new version of unity is actually really good. I'm downloading it right now.
+PhazonSouffle that wouldn't help, as principia is nut currently multithreaded
I was really hyped for playing with this mod, until I saw this video and realised I'm not smart enough to properly use it.
+Giannis Pantazis Honestly I just shoot into the vicinity of the moon and hope fore a capture.
Scott Manley Welp, if you can't do it, there's no way I will. Besides, attempting to ise this on my coal-powered PC would probably make a bigger explosion than the N-1 disaster.
+Scott Manley Where can Ilearn to play ksp like an actual scientist?
+Scott Manley Would an Aldrin Cycler be possible with this mod?
+Johiah plays games from scott manley....
there is some de-orbiting many people want to see in the eve system.
+TheNerd484 Yeah I think thats a great idea, please make a video where you deorbit Gilly.
Totally!!
***** Well, the math is not nice if you want to do this without cheating.
+James Heineman but that was without principia, and he didnt say it was impossible, per say, just near-impossible. it would take insane ammounts of fuel and etc. but with principia it might be, if u have some cheats on maybe.
hm.... deorbit a multi kilometer wide asteroid into a unsuspecting planet? SURE! unfortunately if hyperedit is to be believed the two bodies would just faze through each other :/
Now I can see why they only model one gravitational body in the vanilla game XD
Still, looks pretty cool
It's like Ferram for space.
Years later, Principia works fine on Linux and Mac, has its own download (from a Google Drive) and a thread on the KSP Forums. I wouldn't even consider running Realism Overhaul without it.
Finally, n-body physics!
+OtakuMage dont you mean: oh god, n-body physics!
Azivegu no, I mean "yay, n-body physics and working Lagrange Points! Now I can set up my replica of Sides 1-5 and re-enact the One Year War in KSP!"
I'll stick to my single-body physics, thank you.
+clamchowder138 ...along with a lot of other UA-cam commenters.
You couldn't enjoy getting to Mun with less than 800 m/s of delta-v
I'd love to see more videos with this mod, illustrating the wrong intuitions we get from standard KSP, and exploring different things that are only possible with it, like the use of the "interplanetary transport network."
as a college freshman intending to study engineering, I must say that the vast amount of knowledge you have in real life physics and science is so inspiring! keep up the amazing work!
Hows that engineering going
"Doing Gravity Properly" is a pretty hefty claim if you think about it. I don't think Einstein would approve!
+pseudocoder78 Well, more properly than some sort of arbitrary SoI system.
+pseudocoder78 at least it's better than kepler
No, but Newton would approve. In some way, though, if he was aware of KSP, that would mean, he also knows about Einstein and relativity, hell, he would happily learn about QED, string theory or quantum mechanics too!
This mod needs to be added to Serious Business.
I understand this doesn't have a stable release yet, but when it does, I think it would deserve its own video series.
Yes, this is me begging.
Pretty please?
I think that is the most awesome mod I have seen now.
I'm really glad they've made progress on this, hopefully we will see a full release soon.
+Grim187 Yea please
For my Masters Thesis I worked out how to use the Martian L points to do a low energy transfer to Mars. ~20% fuel saving for an double the flight time.
Cool! I wonder will NASA look at your papers and use them?
+Io That would be really cool, but isn't the main concern the high radiation that astronauts have to deal with? I think it's a little higher than the ISS plus however long they stay on Mars.
Io I didn't get a chance to publish unfortunately, left my masters and went straight into a PhD in a different subject.
gajbooks totally correct, my thesis presented it as an option for supply missions or science missions where flight time is less of a factor. No good for human space flight.
+Io Getting there is one of the most dangerous part. (Great landing is a requirement, good will leave you stranded )
You want to get there as fast as possible while keeping cost down. Double the flight time seriously impacts the risk of life-support failure or a CME from our thermonuclear fun ball cooking them alive. Sorry, somehow turned this into a meat sack lead endeavor.
I am in awe. I have been waiting and wishing for something like this to be available for KSP. I think I may challenge myself to visit each Lagrangian point. The criteria for "visit" will have to be defined of course.
+Nolansykinsley visit could be placing a sattelite
+Danish Raven I have a feeling that they won't exactly be stable, satellites will not like to stay in place, most l points are only stable on one axis.
People saying your videos make them not feel so smart. This video (like many of your others) kicks up my enthusiasm for learning this stuff.
I so want this mod to play with now!
+lyianx If they feel inadequate, they are already connected to the internet which is near infinite knowledge. Why not delve into some astro physics?
so this is why NASA use super computers to calculate their orbital insertion burns.
+FLY Yeah, just doing a simulation in KSP isn't exactly accurate.
+FLY X Especially when you think about all the gravity assists they're building into the transfer orbits.
+Platinumcoated "...and besides - It Works In Kerbal Space Program!"
I mean, you can calculate it on your laptop with GMAT... most of the math isn't actually difficult. It just depends on how detailed you want to be and how accurate you want to be.
If you play real solar system with principia you can actually use GMAT to plan your missions. It's pretty cool.
I mean, we sent man to the moon with less computing power than some kitchen appliances have nowadays.
I would love to see a video with someone inserting a space station into a Lagrange point.
Hey Scott? Wink wink, nudge nudge?
+Xaios
L1, L2, and L3 points are "painful" as they require active stationkeeping. L4 and L5 (the "Trojan" points) though are stable. That's why Jupiter has a collection of asteroids in both of it's L4 and L5 points with the Sun.
#makegravitygreatagain
Can we now de-orbit a moon? Perhaps a 500,000 sub special?
+Gorgan184 Celestial bodies are still fixed on rails. This mod just makes it so that their respective gravities all affect your craft, insteasd of the current SoI affecting your craft. I'd be interested to see if this mod affects ALL crafts, not just your active one.
(Of course, if you make a moon out of parts.... :3)
+Gorgan184 All bodies are welded onto rails sadly, thou mods may help.
+Mach n' Grace 12:14 doesn't look like rails to me.
Trioct
"Mods may help"
LazyLife IFreak Luckily, I wasn't replying to you. ;)
Thanks Scott, been some time since you posted a video like this. This mix between videogames and education is why I subscribed in the first place. Keep it up :)
Every time I feel smart, I watch a Scott manly video and realize I'm not
+Itthumyir You could almost say...he's bringing you right back down to earth ( ͡° ͜ʖ ͡°)
+Tom Meakin slow clap
+Itthumyir Every time I look at the comment section, I realize compared to your average Joe, I'm intelligent .
+Thomas PlaysTheGames My name's not Joe
Checkmate
Time to look at the 2020 version of Principia Scott!
They should alter the integration jump value based on the change in the velocity vector of the previous integration point. That way, they can plan forwards in time far further than they would be able to before and you can have more interesting orbit planning.
Is it just me, or does it look like the Jool system will eventually tear itself apart with all those crazy oscillations? o.O
Awesome video, Scott, and awesome mod indeed. I'm not going to use it, but I'm definitely happy that something like this exists.
P.S. You do realize that you are going to have to put something in one of the Lagrange point now. You _know_ you want to.
Realistically Tylo would definately destroy the system. Most likely the innermost moon (forgot names cuz im a noob) will eventually be tugged out to intersect the second or third, similar to how mercury is going to hit either venus or earth in 3 billion years (tugs from venus and jupiter will increase eccentricity)
Now we just need a mod to derail the celestial bodies.
+Dr_Somgosomgo That’s what this does. None of those bodies are on rails.
+Nicholas Escalona I think you misunderstood my meaning of "derailing". I'm talking about derailing that allows de-orbiting Minmus or Gilly with a big enough rocket.
@@Somgosomgo Yes, you can do that with this mod.....
I'd love to see Scott revisit this mod, this is by far the best video demonstration/explanation of Principia around, but the mod has changed so much (recently it got a view for equipotentials, for example) that a lot of the limitations mentioned here no longer exist.
scott please try to put something in a Lagrange point :D
i would also love to see you use a rocket to drastically alter the orbit of ike
Gilly
Keyon Rosen
yes, gilly. i would be a touch harder
I would love a mod that extends the atmosphere, so you have to re boost your space stations like the ISS has too.
+FLY X that should be in stock KSP for sure. it's odd that you can orbit just fine 1 m above the atmosphere and have a decay orbit 1 m below.
yeah, and as this video shows, it is possible to get around the 'on rails' orbiting system when you don't have the craft selected.
Only if there's also a mod to allow it to boost itself. Managing the extra delta V and planning out an engine to do that sounds cool but micro-managing who knows how many spacecraft you have up there sounds terribly tedious.
you could have it so only crafts over a certain part count are effected by it. and you could have an option to change the max part count before the mod/feature is effective.
+zelodec Well, I'm sure my CPU is happy that there is a clear limit cap the physics / aerodynamics bubble. Above the atmosphere KSP calculates a 'rail', a fixed parabola where the position of your ships have only one variable, namely the speed along the rail. This makes it possible to significantly increase time acceleration, as the position of your craft becomes a 'simple' equation.
In the atmosphere both aerodynamic, heating and structural calculations are performed. To my knowledge, physics acceleration is achieved by increasing the delta between the next iteration of calculation. This can cause slightly unstable situations (like the internal forces of your ship) to become unstable within a few calculation steps, exploding your ship.
Scott you should de-orbit gilly with this mod
This was really awesome to see! I'm an aerospace engineering student but I'm only in my first year so I haven't quite gotten to stuff like this, but I'm so excited for my classes that teach my how to mathematically model orbits like this..
This actually goes a long way to explain why orbital predictions in my current cs project sort of falls apart when I encounter my moon
+TAPE Gaming are you predicting the orbits or just doing it all real time.
xFIRSTx I'm calculating the orbit every frame
I've been waiting for a mod like this for a long time! Thanks!
Scott you CAN increase your plan length to see farther. It's the first slider
finally an N body mod man I have been looking for one for so long.
Will you be adding this to Spaceships Are Serious Business?
+Dominique-Antoine Rossi (domirossi)
this comment accually made me laugh pretty hard :D
I made an inefficient n-body gravity simulator in Unity. It was mesmerising to sit and watch how tiny changes in the objects starting conditions could yield completely different orbits and interactions.
This is running so well! Last time I checked (maybe half a year ago), the mod dev said something along the lines of "it doesn't run even close to playable speed yet even on a very good computer"
What an incredible mod, wish Ksp or Ksp 2 found a way to get Lagrange points
This mod is so cool and you demonstrate it really well.
So...
Does it model the gravitational pull of a spacecraft on objects? Because I really want to capture an asteroid with a gravity tractor.
at this stage of trying out Principia I can't even figure out how to get in to orbit without piloting manually... I'm sure I'll figure it out eventually but was looking here for info on how to use it.
Edit: MechJeb 2 lol. I also installed Realism Overhaul and Real Solar System, so now the learning curve really got steep lol. ;)
I saw you in the chat when I was downloading it a couple weeks back and have been waiting for this video ever since lol
Has anybody, anywhere, actually made some detailed tutorials on KSP with Principia? Subjects like Munar transfers and landings, interplanetary missions, typical KSP thoroughfare like that?
How did I miss this for four years? BTW the channel Reach has put a satellite in L3? orbit in KSP using this mod.
I'm so glad you looked at this mod! I love that this is a thing
In 23 years there'll be a video on the mod for ksp 3 called relativity which would use the einstein field equations (the system of 9 nonlinear partial differential equations) to model gravity lol
Dev notes on the Jool system:
“When using stock, the Jool system is modified, cancelling the apocalypse [github.com/mockingbirdnest/Principia/issues/631]. Specifically, we make the inner Jool system nonresonant, since we have been unable to replicate the results (Manley, priv. comm.) according to which some interpretations of the orbital elements yielded a stable Laplace resonance, despite systematic searches of the Jacobi osculating elements. In addition, at Scott Manley (@illectro)'s and @UmbralRaptor's suggestion, we put Bop in a surprisingly stable, though highly precessing, retrograde orbit [goo.gl/photos/xXh83HTejv8vo8daA]. The modified system is stable for upwards of a century.”
Wow, thanks Scott, either you saw my comment on one of your recent videos or we are on the same (de Broglie) wavelength!
KSP2 is adding interstellar travelling, which means MOAR physics like general and special relativity!
These things become more important than the Newtonian physics as you approach the light speed.
I actually learned a bit about space from this! It's weird how hard we consider orbits in the real world, despite all the physics acting out against this concept that space is consistent and likes to stay in the same place.
a great way to increase CPU usage to match the GPU usage of EVE Volumetric, Scatterer, Deferred, Parallax, etc
Wow, that is a really cool way of explane the gravity working, relating to a very small and known system - the kerbin-mun one. By the way, I really like the navball's colours and "font".
You should use this on your "kerbal spaceships are serious business" series!
Now i understand why the orbits in Universe Sandbox 2 were very different that the ones in KSP
This looks super cool.
Not sure if this is already an option but while they work on getting the solar system stable they should let you keep the planets and moons on rails but still apply all the gravity to your vessels.
Reminds me of my computational physics class, haha. All about that RK-4 method for Jupiter's effect on the Moon's motion around Earth yo.
Likely mod dev. opinions on the cap thing: "Gorramit, Scott, it's a videogame, not a physics simulator!"
You should totally do a Realistic Space Program mkII series with this mod added...
Would it not be better if the mod continued to have the planet on rails and instead just apply the new realistic forces on the spacecraft?
+Joachim Voldseth You're right I think, cause looking at that time lapse of Jool, after playing the game for 1 or 2 kerbal years i think most, if not all, of those moons would not be orbiting Jool.
Plus, the cpu savings.
That is a great mod, should be implemented in stock Kerbal asap! Maybe with some optimizations such as not considering the gravity of Moho when in orbit around Tylo etc.
the main reason I want this in the game is for those sweet, sweet, Lagrange points.
For staging rockets, you should use clamp-ottoman so you can later use the for in space use.
realism overhaul + principia + a satellite contract:
cmon morty we'll just send a probe to space, in and out 20 mins adventure
Amazing, I hope this gets integrated into the base game.
RIP CPU though.
This is useful for looking at how things work in real life (more or less), but it would be a disaster for the game if it was included in it. It's chaos in its physical sense. Dealing with that, predicting even the simplest things' outcomes, requires supercomputers. That's why we use those when working with real life spacecraft orbits planning.
In KSP, it would mess up a lot of things and it would not be fun. I'm speaking as someone who plays with realistic mods and was a strong advocate for including reentry heating when most of people were bitching against it.
This is going to be super popular.
+TheSpacecraftX I'd say it depends on the usability. For instance Scott does not mention how far you can plan ahead, that might be an issue.
DummyUrD He does mention that in the video. He says it is a bit limited and shows that limit in the video.
limited is a very vague term though
DummyUrD Watch the video he shows the limit of it I think.
+TheSpacecraftX I don't think so. Most will prefer simple orbits. People are outraged because half second imperfect satellite orbits in stock. with n-body any orbit is a mess More complexity not lead to wide popularity. But there definitely people who will like it
i wish this would get updated for the latest ksp version. i want to watch my massive planet mod pack with 107 bodies turn into a blender of a solar system.
I am super surprised the planets don't kick each other out the system relatively quickly
+Twitchi Does that happen in real life???
+Greg m Over huge amounts of time, various bodies get ejected out of orbits around other planets in our solar system, but the Kerbal Space Program system uses bodies that have an analogue mass to our solar system, but are 10x smaller, the orbits are also significantly closer. This could cause massive instability, I'm not really sure, but the mod makers probably toned the planets effecting eachother down a bit to follow the "10x smaller" thing.
Greg m oh hell yeah it happens.. the only reason our system look as stable as it is now is because all the bodies out of resonance got kicked out long ago.. probably during the heavy bombardment..
+Greg m
No, but the KSP solar system is also pretty wonky, because it was never designed with stability in mind. That doesn't happen *anymore* in the real solar system, because anything big that would have gotten kicked out has already been kicked out, but when it was just forming things were pretty chaotic. (It's currently thought, for instance, that our Moon formed when a body the size of Mars crashed into early Earth, and the Moon formed out of the stuff that got blown off.)
wow, I was wondering why our videos never showed in my subscription feed...I wasn't subscribed...fail!
So that's those 2 lines you see in movies when they show satellites on maps ! Like goldeneye for one , had a eureka moment haha
All of these mods adding to the game in incredibly impressive ways, yet no one has figured out orbital tilts yet?
wow thats awesome, thats how gravity should be calculated in the default game
I love how the past few years of KSP have changed and defeated expectations.
"We can never have multiplayer." Players mod in multiplayer.
"x64 for Windows will never be a priority" It's coming imminently.
"n-Body simulation in KSP is completely impossible" And now we've gotten an n-body simulating mod.
+Cleric This makes me excited for whatever "Impossible" thing will come to the game next thanks to modders and players!
Can't believe they got this to work! amazing
13464110.04162249 km should be the Kerbin-Kerbol L1 orbit. Assuming I didn't screw up somewhere.
+Timgor did you use equeisions or used machinary estimation too?
there should be a fifth-degree equesion that cannot show roots usually
orbitsimulator.com/formulas/LagrangePointFinder.html
Timgor
thanks for the link!
Could you make a video time lapsing the orbits of Jool's moons or the solar system? I would like to see planets kicked out into interstellar space.
@ScottManley, I would love a series of videos on this mod.
+Scot Manley Do you have tutorial videos showing us what mathematical equations we could use to planning launch ascents? Or how about showing us step by step how do you plan out a mission (payload mass, DV needed, type of launch system needed, etc)?
So does getting a geostationary orbit requires more speed to work? It seems that a distance of 5000 km (which IRL would be 50000 km) doesn't make the satellite rotate slowly enough to be geostationary, though in stock it's supposed to be even less than 3000 km.
Does Principia make object orbit faster than the vanilla game?
Will you be using this in your Serious business series? :) Very informative video as always.
I hope KSP 2 gets some great new features like this. I would love to have the option to turn this on just for the chaos factor.
Personally I'm all for Bop getting slingshot out into space. That'd make for an interesting timelapse.
+Energy Core Think about chasing it with a spaceship and landing on it! That would be pretty cool.
According to my calculations, if my sources are correct and if my calculations are not wildly off, the number of neutrons in the observable universe is 1.194x10^94. I did this by measuring the number of neutrons in the solar system, multiplying that by the number of stars in the galaxy, taking tha number and multiplying that by the number of estimated galaxies, and there you go. If there are 10^24 protons per gram of matter, than my calculations are at least in the ball park.
Give or take a few sextillion
If I had to guess, I would say that the reason for the path length limit is probably that N-body simulation eats CPU cycles like nobody's business.
Wow, looks like they know who they are hiring on for KSP 2.
Correct me if I'm Wrong but is this the reason the moon is moving away from the Earth?
You should do a video on the intraplanetary transport network.
wow this mod is awesome! Hope you can do more videos about this mod
If there are any planet pack makers here, I'd love it if you could make a doughnut planet with two moons. One floating in the middle and another with a figure-8 orbit through the middle
I have always wanted to orbit my spacecraft around Lagrange points in ksp. Now, I can.
Wait, Bop's on a retrograde orbit?!
The Jool-5 challenge just got a whole lot harder . . .
my god I want to install this mod so badly, but I guess I'd become so frustrated since I have no idea how to make space work...
this is really a mod for those space engineers that brings back work to their home, well now they can bring back work to their games.
I love it, but I'd totally suck at it :D