egg changed the topic of #principia to: Logs: https://esper.irclog.whitequark.org/principia | <scott_manley> anyone that doubts the wisdom of retrograde bop needs to get the hell out | https://xkcd.com/323/ | <egg> calculating the influence of lamont on Pluto is a bit silly…
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<queqiao-_> ⟨O​slov⟩ Ironically, I am looking at patching abandoned or authorabsent mods right now to work with this new celestial. I must love punishing myself.
<queqiao-_> ⟨O​slov⟩ Not principia though. Even if it were possible, I am pretty sure that is the only mod that is legit scarier to work on than Kopernicus. Mad respect to you guys.
<queqiao-_> ⟨O​slov⟩ Not principia though. Even if it were possible or needed, I am pretty sure that is the only mod that is legit scarier to work on than Kopernicus. Mad respect to you guys. (edited)
<queqiao-_> ⟨O​slov⟩ Since we are talking cats, my cat legit won't eat anything but canned food. She thinks kibble is rocks or something
<queqiao-_> ⟨P​aculino (ŝi/ri/she/they)⟩ So, now you are the linuxgamerguru of planet pack patches?
<queqiao-_> ⟨O​slov⟩ Taking up the reigns of Kopernicus painted a target on my head yes
<queqiao-_> ⟨O​slov⟩ I'm still wondering why I did it, beyond the "so I can play my game" reason
<queqiao-_> ⟨O​slov⟩ I did not think the day would come when I'd break something this badly though. Adding a celestial, even when it's removed from the local bodies list, messes with any mod that looks at celestials. Who would've guessed.
<queqiao-_> ⟨O​slov⟩ I mean that's almost reasonable
<queqiao-_> ⟨P​aculino (ŝi/ri/she/they)⟩ How much stuff did you try before you found out that this worked?
<queqiao-_> ⟨O​slov⟩ A lot... We got so far to determine the origin of the bug is somewhere in the making history mission editor, which makes about as much sense as it sounds
<queqiao-_> ⟨O​slov⟩ which is why MakingLessHistory fixes it
<queqiao-_> ⟨O​slov⟩ I have about 1 whole year of research and various tests involved in that one bug
<queqiao-_> ⟨P​aculino (ŝi/ri/she/they)⟩ So it does not affect installs without making history?
<queqiao-_> ⟨O​slov⟩ no, it doesn't. Well, usual floating point weirdness still, but not the particular "anything beyond 10x rescale eeloo range" bug
<queqiao-_> ⟨O​slov⟩ which is about where things start getting odd
<queqiao-_> ⟨O​slov⟩ and I mean, I understand why I can't use yottameters and such. That's just asking too much of this game
<queqiao-_> ⟨O​slov⟩ if you do, floating point errors get so bad you sink into the launchpad because PhysX is basically dead
<queqiao-_> ⟨O​slov⟩ If you have a kerbal exit, they are usually poofed or kraken'd into hyperspace. But yeah that's just typical "way too big to represent with the variable type" errors and not related to this bug
<queqiao-_> ⟨O​slov⟩ I determined with this fix the effective workable range is about 1/100th of a yottameter, which is plenty good IMO.
<queqiao-_> ⟨e​gg⟩ (note to self: there the ULP of a (binary64, binary32) pair—which is what KSP effectively works with—is a handful of centimetres.)
<queqiao-_> ⟨e​gg⟩ (contrast the millimetric binary64 ULP at the distance of the test case.)
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<queqiao-_> ⟨Z​eusbeer⟩ Can she smell things properly?
<queqiao-_> ⟨Z​eusbeer⟩ Our cat was a bit sick, just completely sneezing and stuff, had the same issue, then after healing with some antibiotics she started smelling and eating literally everything
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<queqiao-_> ⟨K​obymaru⟩ I have question about the Voyager 1/2 "Grand Tour" trajectory, is this the right place to ask?
<queqiao-_> ⟨Z​eusbeer⟩ depends on the question
<queqiao-_> ⟨Z​eusbeer⟩ if its about the trajectory, yes
<queqiao-_> ⟨K​obymaru⟩ it is
<raptop> It's difficult to say without additional context, but it should be doable in Principia, possibly including the alternate trajectory that would take Voyager 1 to Pluto
<queqiao-_> ⟨K​obymaru⟩ I've done it in principia a few years ago, but this time I'm having trouble
<queqiao-_> ⟨Z​eusbeer⟩ As long as you get the launch window right (which is freaking huge) you should be fine
<queqiao-_> ⟨K​obymaru⟩ so the IRL probes launched 1977. I seem to recall that the window for the great tour trajectory stretches pretty much through the whole 70s, is that correct?
<queqiao-_> ⟨Z​eusbeer⟩ just try to set up the maneuver to Jupiter and the rest is easy
<queqiao-_> ⟨K​obymaru⟩ well here's the thing about that
<queqiao-_> ⟨Z​eusbeer⟩ IRL it used 200-400 m/s DV for corrections
<queqiao-_> ⟨Z​eusbeer⟩ which is a lot
<queqiao-_> ⟨Z​eusbeer⟩ go to jupiter first, set it up so that it is as close as possible to saturn
<queqiao-_> ⟨Z​eusbeer⟩ correct once you passed jupiter so you are onto a saturn -> close to uranus trajectory
<queqiao-_> ⟨Z​eusbeer⟩ etc
<queqiao-_> ⟨K​obymaru⟩ This is what I got now
<queqiao-_> ⟨K​obymaru⟩ So far I've only got the jupiter encounter, and it is as close as possible to jupiter as I can get without exploding (1500km), so this is already "maximum bend" at jupiter
<queqiao-_> ⟨K​obymaru⟩ that "bend" is still not enough to bend me to Saturn
<queqiao-_> ⟨Z​eusbeer⟩ This looks incorrect, you shouldn't be requiring such a big correction between Earth and Jupiter
<queqiao-_> ⟨Z​eusbeer⟩ the burn from Earth should already bring you super close to Jupiter
<queqiao-_> ⟨K​obymaru⟩ The correction is simply a planning utility, because the departure burn is extremely sensitive. Rest assured that it still doesn't work with no correction
<raptop> Pioneer 11 launched over a year later, so wouldn't have had to bend so much for the Jupiter -> Saturn part
<queqiao-_> ⟨Z​eusbeer⟩ Yes I would tweak the launch window a little bit
<queqiao-_> ⟨Z​eusbeer⟩ 1972 seems quite arbitrary
<queqiao-_> ⟨K​obymaru⟩ So my theory why this trajectory is wrong is: it's simply too early, and the angle between jupiter and saturn is quite high, and I just don't have enough "bend" for it
<queqiao-_> ⟨Z​eusbeer⟩ maybe you can get to uranus from jupiter?
<queqiao-_> ⟨Z​eusbeer⟩ that might be fun to try
<queqiao-_> ⟨K​obymaru⟩ well it's the earliest time I could do it with my current career. I thought the window was supposed to be all of the 70s, but now I'm not so sure anymore
<queqiao-_> ⟨l​pg⟩ given that you already have a good idea of dates and travel times, this seems like an idea case to feed to KSPTOT and see what comes out
<queqiao-_> ⟨Z​eusbeer⟩ It is a big window for sure, but the optimal window is at 1 specific point
<queqiao-_> ⟨l​pg⟩ "the window" isn't a magical binary thing. the farther out you are from the center, the more the dv requirements are likely to vary too
<queqiao-_> ⟨K​obymaru⟩ Is KSPTOT still close enough for Pricnipia? Because it had n-body gravity support theoretically, but I could never get it to work
<queqiao-_> ⟨l​pg⟩ yes
<queqiao-_> ⟨K​obymaru⟩ I have "loads" of dV, but if I add more dV, I actually lose bendiness at jupiter
<queqiao-_> ⟨l​pg⟩ given that you already have a good idea of dates and travel times, this seems like an ideal case to feed to KSPTOT and see what comes out (edited)
<queqiao-_> ⟨K​obymaru⟩ so the problem becomes even worse
<raptop> I'm guessing "too early" in part because apparently Pioneer 11's flyby was like 1.6 Jupiter radii at perijove
<queqiao-_> ⟨K​obymaru⟩ hm ok, I'll give it a try then
<queqiao-_> ⟨S​umguy⟩ try a burn at Jupiter periapsis
<queqiao-_> ⟨l​pg⟩ you can't _just_ add dv
<queqiao-_> ⟨Z​eusbeer⟩ I have not tried KSPTOT with principia and barely got it working 'close enough' with stock
<raptop> yeah, what sumguy typed would be interesting
<queqiao-_> ⟨Z​eusbeer⟩ I would suggest just waiting 1 to 7 years
<queqiao-_> ⟨Z​eusbeer⟩ the voyager 2 window is fantastic
<queqiao-_> ⟨l​pg⟩ everything feeds into everything else, LAN, departure time, dv, travel time...
<queqiao-_> ⟨K​obymaru⟩ I've used TWP for all that, picking a point with 8300 m/s (my upper stage dV), and tried that as well. Do you use KSPTOT or TWP for this?
<queqiao-_> ⟨l​pg⟩ I've only ever done one gravity assist, so neither. but I have no doubt that TWP is completely the wrong tool for it
<queqiao-_> ⟨l​pg⟩ TWP is great at finding least-dv transfers, which gravity assists basically never are
<queqiao-_> ⟨Z​eusbeer⟩ I am an absolute caveman and use flyby finder for stuff like this 👺
<queqiao-_> ⟨Z​eusbeer⟩ But flyby finder is just so weird and buggy to use
<queqiao-_> ⟨Z​eusbeer⟩ It's a shame they never updated it, it still somewhat works for the latest ksp versions
<queqiao-_> ⟨Z​eusbeer⟩ I believe senpai Reach used it for his flyby of everything video
<queqiao-_> ⟨K​obymaru⟩ Helps a tiny bit, but I only brought 200 m/s because the plan was to freefall pretty much everything
<queqiao-_> ⟨l​pg⟩ also worth bearing in mind that there's very little that's intuitive here. it's entirely possible that "maximum bend" isn't what you want
<queqiao-_> ⟨K​obymaru⟩ if I use less bend, I get even further from Saturn
<queqiao-_> ⟨l​pg⟩ doesn't mean anything. the _direction_ of the bend is more important than the amount
<queqiao-_> ⟨l​pg⟩ you could be approaching jupiter from completely the wrong side, or anywhere in between
<queqiao-_> ⟨l​pg⟩ my point is that I wouldn't even bother _trying_ to logic it out. use the tools
<queqiao-_> ⟨Z​eusbeer⟩ I think you guys have different definitions of bend
<queqiao-_> ⟨Z​eusbeer⟩ LPG is correct though
<queqiao-_> ⟨l​pg⟩ if ksptot tells you "forget it", then forget it. if it finds a way, _then_ you can start wondering about what you're doing wrong
<queqiao-_> ⟨K​obymaru⟩ that part is pretty intuitive actually. I can see the trajectory going away from saturn if I increase the Perijove
<queqiao-_> ⟨l​pg⟩ you've found one local minimum, congrats
<queqiao-_> ⟨l​pg⟩ how many others are there that you haven't found?
<queqiao-_> ⟨Z​eusbeer⟩ try approaching from the other side of jupiter
<queqiao-_> ⟨Z​eusbeer⟩ the polar sides
<queqiao-_> ⟨Z​eusbeer⟩ using the moons can also help
<queqiao-_> ⟨Z​eusbeer⟩ it's one big puzzle
<queqiao-_> ⟨K​obymaru⟩ OK so while the departure obviously has a lot of parameters, ( LAN, departure time, dv, travel time...) and all that, a gravity assist is still a gravity assist and not magic.
<queqiao-_> ⟨K​obymaru⟩ "Pass in front of a celestial body to brake and behind a celestial body to accelerate"
<queqiao-_> ⟨K​obymaru⟩ I want to accelerate, so I pass in front
<queqiao-_> ⟨K​obymaru⟩ I want to accelerate, so I pass in ~~front~~bach (edited)
<queqiao-_> ⟨Z​eusbeer⟩ I mean you have a maneuver planner, you can easily try different approaches to see what they dio
<queqiao-_> ⟨Z​eusbeer⟩ I mean you have a maneuver planner, you can easily try different approaches to see what they do (edited)
<queqiao-_> ⟨K​obymaru⟩ I want to accelerate, so I pass in ~~front~~back (edited)
<queqiao-_> ⟨Z​eusbeer⟩ as long as your game doesn't crash 👺
<queqiao-_> ⟨K​obymaru⟩ Well so far it's running at around 3 FPS thanks to #3035
<queqiao-_> ⟨K​obymaru⟩ but its running
<queqiao-_> ⟨l​pg⟩ unfortunately, this is the sort of gross oversimplification that amounts to magical thinking
<queqiao-_> ⟨Z​eusbeer⟩ Just program a multiple shooting algorithm with KoS and use that to find the optimal flyby 👺
<queqiao-_> ⟨l​pg⟩ ugh. the moons of Uranus going retrograde is freaking me out every time I see one zoom by
<raptop> distant retrograde orbits strike again?
<queqiao-_> ⟨K​obymaru⟩ Of course the exact numbers differ significantly, but I believe the basic principle still applies. Can you point out the oversimplifications that break it?
<queqiao-_> ⟨K​obymaru⟩ I think it's really just too early, and Jupiter is in the wrong spot. If the phase angle to Saturn would be smaller, it should be possible to use with the amount of "bend" i have available
<queqiao-_> ⟨K​obymaru⟩ The amount of "bend" would be the bend angle from this answer:
<queqiao-_> ⟨K​obymaru⟩ https://space.stackexchange.com/a/6510
<queqiao-_> ⟨K​obymaru⟩ The amount of "bend" would be the bend angle δ from this answer:
<queqiao-_> ⟨K​obymaru⟩ https://space.stackexchange.com/a/6510 (edited)
<queqiao-_> ⟨K​obymaru⟩ According to this, the bend angle δ depends on the incoming velocity and the approach radius r which is (body radius+perijove)
<queqiao-_> ⟨K​obymaru⟩ So if I go slower, I get a higher δ.
<queqiao-_> ⟨K​obymaru⟩ I'm pretty much limited with the approach velocity because my upper stage has 8500 m/s of dV, but I think IRL Voyager had even less than that
<queqiao-_> ⟨P​aculino (ŝi/ri/she/they)⟩ Are you sure you are planning the launch at the best time?
<queqiao-_> ⟨K​obymaru⟩ and I can only change the approach direction by choosing launch windows in different years. There's nothing I can do with my Escape trajectory to change that.
<queqiao-_> ⟨K​obymaru⟩ Well, I'm finding that apparently, I am not. I need to wait a few more years.
<queqiao-_> ⟨K​obymaru⟩ Welp, changing craft name to "Pioneer 10" or something, lol
<queqiao-_> ⟨K​obymaru⟩ and I can only change the approach direction by choosing launch windows in different years. There's nothing I can do with my Escape trajectory to change that.
<queqiao-_> ⟨K​obymaru⟩ So I have limited bend angle δ available, and the angle to Saturn is just too much. (edited)
<queqiao-_> ⟨K​obymaru⟩ That looks... almost useful actually
<queqiao-_> ⟨l​pg⟩ when I spoke of KSPTOT, I had the Multi-Flyby Maneuver Sequencer in mind
<queqiao-_> ⟨l​pg⟩ no idea if this would be viable for the 'grand tour' aspect, but just considering earth-jupiter-saturn and hunting around for a <6y mission spits this out
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<queqiao-_> ⟨O​slov⟩ well that's interesting. Principia indeed works fine with faraway bodies, the bug is in the stock code. Specifically a method that is using an OR operator where it should be using and AND... this simple typos screws up the celestialbodies list sorting and leads to the weird bug (as well as our even weirder fix of just stacking a celestial on the list). I've punted this patch over to KSPCommunity
<queqiao-_> ⟨O​slov⟩ well that's interesting. Principia indeed works fine with faraway bodies, the bug is in the stock code. Specifically a method that is using an OR operator where it should be using an AND... this simple typos screws up the celestialbodies list sorting and leads to the weird bug (as well as our even weirder fix of just stacking a celestial on the list). I've punted this patch over to KSPCommunityF
<queqiao-_> ⟨O​slov⟩ If anyone is curious the exact place this happens, I can talk those details in private. I don't like to blatantly violate the EULA in public... lol
<queqiao-_> ⟨O​slov⟩ If anyone is curious the exact place this happens, I can talk those details in private. I don't like to blatantly violate the forum rules in public... lol (edited)
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<queqiao-_> ⟨A​l2Me6⟩ So, no more `KopernicusWatchdog`?
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<queqiao-_> ⟨r​ocketman⟩ That trajectory makes little sense unless the earth is a point mass where you can dive close to its core
<raptop> Tired: spherical cows
<raptop> Wired: pointlike cows
<queqiao-_> ⟨r​ocketman⟩ Fired: the trajectory planner
<queqiao-_> ⟨l​pg⟩ if you're referring to that top SMA, it's just nonsense
<queqiao-_> ⟨r​ocketman⟩ this
<queqiao-_> ⟨r​ocketman⟩ that angle of deflection is _sharp_
<queqiao-_> ⟨l​pg⟩ that would be Jupiter, yes
<queqiao-_> ⟨r​ocketman⟩ ah, so this is possible?
<queqiao-_> ⟨r​ocketman⟩ ah, so this is possible? 🤔 (edited)
<queqiao-_> ⟨l​pg⟩ that's not even hard for Jupiter
<queqiao-_> ⟨r​ocketman⟩ I see
<queqiao-_> ⟨l​pg⟩ that dotted line could be falling straight into the sun if I wanted it to
<queqiao-_> ⟨r​ocketman⟩ what would have to be the altitude of perigee?
<queqiao-_> ⟨r​ocketman⟩ what would have to be the altitude of perijov? (edited)
<queqiao-_> ⟨r​ocketman⟩ what would have to be the altitude of perijove? (edited)
<queqiao-_> ⟨l​pg⟩ pretty high, actually. I don't recall
<queqiao-_> ⟨l​pg⟩ probably not gigameters, but certainly tens of megameters at least
<queqiao-_> ⟨l​pg⟩ (it's really not a sharp angle if one were to zoom in enough)
<queqiao-_> ⟨r​ocketman⟩ true I suppose
<queqiao-_> ⟨r​ocketman⟩ I'm just used to seeing assists off less massive inner solar system planets maybe
<raptop> Jupiter is far too fluffy, can we make it be held up entirely by electron degeneracy?
<queqiao-_> ⟨O​slov⟩ doggie ded