raptop changed the topic of #principia to: READ THE FAQ: http://goo.gl/gMZF9H; The current version is Galileo. We currently target 1.5.1, 1.6.1, 1.7.x, 1.8.1, and 1.9.1. <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… | <egg> also 4e16 m * 2^-52 is uncomfortably large
<discord->
egg. — (if it’s that there is a GameEvent for it)
<discord->
siimav. — I know there's a field for checking whether the easing is in progress...
<discord->
egg. — yeah
<discord->
siimav. — Happen to remember where it is? 🙂
<discord->
egg. — in VesselPrecalculate
<discord->
egg. — isEasingGravity
<discord->
egg. — now of course there are multiple thing, the gravity easing, and the surface ease-in
<discord->
egg. — now of course there are multiple things, the gravity easing, and the surface ease-in (edited)
<discord->
siimav. — `isEasingGravity` is false
<discord->
egg. — OK so that’s not it…
<discord->
egg. — ah but KJR does a physics easing, too, right ?
<discord->
egg. — but that seems to work based on isEasingGravity…
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<discord->
siimav. — Hmm, `Vessel.packed` is true for ~60 fixedupdates
<discord->
siimav. — Tried around 65 now and it worked fine
<discord->
DRVeyl. — Not quite sure if state = PRELAUNCH or not at that point
<discord->
egg. — oh, a packed vessel is probably going to mess with things, yes
<discord->
siimav. — Events aren't really useful for me because I need to clobber the state on each frame
<discord->
egg. — because a growly Principia is ready to pounce on the plane should Prelaunch fail to be set even for a split second
<discord->
egg. — because a growling Principia is ready to pounce on the plane should Prelaunch fail to be set even for a split second (edited)
<discord->
siimav. — I think waiting until Vessel.packed turned false did the trick
<discord->
siimav. — I think waiting until Vessel.packed turns false did the trick (edited)
<discord->
egg. — So there seems to be some sort of underlying eggsplanation even
<discord->
egg. — if we pick up the vessel when it is packed, we are going to pick up a lot of unphysical things
<discord->
Conventia. — Is galileo getting updated or do the fixes wait for the next lunar release? And I'm curious about these user facing features that were mentioned? 😛
<discord->
egg. — we don’t update release
<discord->
egg. — we don’t update releases (edited)
<UmbralRaptop>
Everyone knows egg's solution to the Чебышёв problem right?
<discord->
DanieI. — whats a frenet frame
<discord->
DanieI. — can i delete history
<discord->
DanieI. — my save is getting unwieldy
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<discord->
m_. — I was about to ask a related question. I was wondering why going into/out of the Tracking Station was taking 60s + 2GB, tracked it down to the save time of 50 years.
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<discord->
DanieI. — How did you delete your history
<discord->
Anomaly. — You use the KSP cheat menu and hack gravity.
<discord->
Anomaly. — That erases Principia history by temporarily switching it off for the craft in question.
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<discord->
m_. — Can I do something about these long loading times, though? This happens in new saves as well, I just have to speed through a few decades to notice it.
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<discord->
Anomaly. — Not speed through a few decades
<discord->
Zeusbeer. — Egg goes on past midnight
<discord->
Standecco. — a frenet frame is a frame formed by the tangent, normal and binormal vector of a curve in 3d space
<discord->
Standecco. — in the case of an orbit, tangent = prograde, normal = radial in, binormal = normal
<discord->
Standecco. — in the case of an orbit and KSP's maneuver nodes, tangent = prograde, normal = radial in, binormal = normal (edited)
<discord->
m_. — ... That was a simple reproduction case. I'm asking if there's anything I can do about the load times, since it's a problem in my actual save game.
<discord->
Standecco. — you probably have many vessels. Trajectory History is saved for every vessel, so deleting the oldest ones should result in a much smaller save file (and thus shorter loading times)
<discord->
Standecco. — unless it happens even without vessels
<discord->
Zeusbeer. — Anyone knows if the UT time values for flyby finder work for newer versions of KSP?
<discord->
Anomaly. — Could you clarify what you mean by that?
<discord->
Butcher. — > ... That was a simple reproduction case. I'm asking if there's anything I can do about the load times, since it's a problem in my actual save game.
<discord->
Butcher. — @m_ Running forward 50 years causes slow scene changes.
<discord->
Butcher. — Lots of vessels also causes slow scene changes for *different* reasons.
<discord->
Zeusbeer. — can confirm no
<discord->
Zeusbeer. — took a starting day of 5119200 seconds UT for a kerbin -> eve -> moho flyby
<discord->
Zeusbeer. — took a starting day of 5119200 seconds UT for a kerbin -> eve -> moho flyby from the software (edited)
<discord->
Zeusbeer. — setting up a flight plan showed the launch window was really far off towards eve
<discord->
Zeusbeer. — wait maybe I setup the alarm wrong
<discord->
Zeusbeer. — I'll give it another shot
<discord->
Butcher. — @egg think I broke my principia build:
<discord->
Zeusbeer. — history is a very nice feature
<discord->
Zeusbeer. — )))
<discord->
DanieI. — can i see other bodies positions relative to my craft at certain points in its history
<discord->
egg. — by using reference frames centred on those bodies
<discord->
Zeusbeer. — yes that reference frame is the absolute best
<discord->
Zeusbeer. — it's like the most bottom option and sometimes you could use the one above that
<discord->
egg. — I should remove the third option, it is useless
<discord->
Zeusbeer. — what is it's use?
<discord->
DanieI. — whats the third option again?
<discord->
egg. — barycentric rotating
<discord->
egg. — I used to think this was useful for Lagrange points
<discord->
egg. — it is not
<discord->
Zeusbeer. — I use it for lagrange points
<discord->
egg. — what you need for Lagrange points is the rotating-pulsating frame
<discord->
Zeusbeer. — :magic:
<discord->
DanieI. — rotating pulsating frame
<discord->
egg. — but the rotating-pulsating frame is weird
<discord->
DanieI. — what even
<discord->
egg. — and to be honest, the bottommost frame will do just fine for Lagrange points
<discord->
Zeusbeer. — he's flexing on us mortals again with his extended knowledge )))
<discord->
egg. — the rotating-pulsating frame fixes both bodies at the same time
<discord->
DanieI. — i use barycenter for transfers
<discord->
Zeusbeer. — Bottom option is the best for transfers
<discord->
Zeusbeer. — imo
<discord->
egg. — yeah
<discord->
egg. — Zeusbeer is correct
<discord->
Zeusbeer. — I only really use the second option and the last option
<discord->
egg. — you may ask: what happens if the bodies move apart or towards each other in the rotating-pulsating frame?
<discord->
Zeusbeer. — don't know what the first and the third ones are used for
<discord->
egg. — well, the reference frame stretches
<discord->
egg. — @Zeusbeer first is when you care about the surface: landing, low flight, surface observation & comms
<discord->
Zeusbeer. — maybe instead of removing them hide them behind an "advanced user" button
<discord->
egg. — flying a plane is not really an advanced feature
<discord->
egg. — the first reference frame is very useful
<discord->
egg. — the third one is just utterly pointless
<discord->
DanieI. — keep it anyway
<discord->
Zeusbeer. — how do you abuse the first one then?
<discord->
DanieI. — add 5th option
<discord->
egg. — yes because clearly Principia is too easy to use and confuses nobody, and its UI is too small, so we should keep useless crud around :-p
<discord->
Zeusbeer. — You should make a "simple option"
<discord->
DanieI. — the last option makes my original orbit look like spiral
<discord->
Zeusbeer. — where instead of complex names you just have "transfer view" and "normal view"
<discord->
Zeusbeer. — and surface view
<discord->
egg. — @Zeusbeer no
<discord->
Zeusbeer. — xd
<discord->
egg. — I should, on the other hand, rename the fourth frame to be in line with actual usage
<discord->
Zeusbeer. — a "simple mode" sounds like an easy if statement button
<discord->
egg. — geocentric ecliptic, Jupiter Sun Orbit, etc.
<discord->
egg. — @Zeusbeer OK I am going to ask you to stop making statements about what is easy and hard
<discord->
DanieI. — jupiter sun orbit?
<discord->
Zeusbeer. — yes I don't know about anything
<discord->
Zeusbeer. — I can only program a bit in php/html/mysql/python
<discord->
Zeusbeer. — but very little
<discord->
DanieI. — i know modern c++ and c# hire me
<discord->
egg. — Jupiter-Sun-Orbit is the name that people actually use for what Principia currently calls Jupiter-Centred Sun-Aligned
<discord->
DanieI. — whats it for
<discord->
Zeusbeer. — the name that people actually use makes more sense yes
<discord->
egg. — transfers/rendez-vous, orbits synchronous with the parent (e.g., sun-synch orbits for a planet)…
<discord->
DanieI. — why use jupiter sun for a rendezvous instead of just jupiter centered
<discord->
egg. — because you are coming from an orbit around the Sun
<discord->
Zeusbeer. — so if you are planning a transfer Earth -> Jupiter
<discord->
Zeusbeer. — you would use Jupiter-Earth-Orbit
<discord->
Zeusbeer. — ?
<discord->
egg. — that is not a thing
<discord->
DanieI. — how would that even work
<discord->
egg. — Jupiter does not orbit the Earth
<discord->
DanieI. — center the line between jupiter and earth lol
<discord->
egg. — yeah that would be very pointless
<discord->
Zeusbeer. — lol I misunderstood
<discord->
DanieI. — i understand
<discord->
Zeusbeer. — I'll stick to my brainlet 2 reference frames
<discord->
DanieI. — huh yeah you're right egg
<discord->
DanieI. — 3rd frame is useless
<discord->
egg. — @Zeusbeer I mean, the surface frame is quite obvious
<discord->
DanieI. — my eye open
<discord->
egg. — just fly a plane
<discord->
Zeusbeer. — will try maybe yes
<discord->
egg. — (it even has the same navball as stock)
<discord->
Zeusbeer. — does it help for flying landers aswell?
<discord->
DanieI. — also useful for geosynchronous right
<discord->
egg. — sure, because you can see where you will land in map view
<kmath>
<eggleroy> Michel Capderou (2012), Satellites : de Kepler au GPS. https://t.co/vAqW1Adq8Z
<discord->
DanieI. — how does a stretched frame work
<discord->
egg. — the problem is our framework for geometry and physics does not like stretchy frames
<discord->
DanieI. — i dont either
<discord->
Zeusbeer. — your cat truly enjoys the book!
<discord->
egg. — (another problem is that a stretchy frames would be very likely to confuse users)
<discord->
DanieI. — rotating frames already melt my brain
<discord->
Zeusbeer. — I really enjoy the rendezvous target centered frame
<discord->
Zeusbeer. — out of all the things in principia
<discord->
egg. — (there is an English translation of this book if you prefer that to French: *Satellites, from Kepler to GPS*)
<discord->
DanieI. — the rendezvous target centered frame also melts my brain
<discord->
Zeusbeer. — I manged to intercept an astroid 3 days ahead coming from a solar orbit into kerbin
<discord->
Zeusbeer. — in 300 meters
<discord->
Zeusbeer. — lol
<discord->
DanieI. — barycentric is still the next best thing we have for lagrange points until we get a pulsating frame?
<discord->
egg. — @Butcher did you manage to rebuild the thing with your fix?
<discord->
Zeusbeer. — how would a pulsating frame view look for a lagrange point?
<discord->
egg. — @DanieI no, for L1 and L2 the fourth frame (secondary-centred orbit) is strictly better
<discord->
egg. — @Zeusbeer the Lagrange points are defined in that frame; they don’t move in that frame
<discord->
DanieI. — in that frame what would l1 and l2 look like?
<discord->
Zeusbeer. — woah I think I see what you mean
<discord->
egg. — in all the current frames, Lagrange points move around as the bodies move apart and towards each other
<discord->
Zeusbeer. — it's basically seeing the lagrange orbit in the center and you can see how everything moves around it
<discord->
egg. — Lagrange Orbit? that is not a thing
<discord->
Zeusbeer. — well no indeed
<discord->
Zeusbeer. — it's basically seeing the lagrange point in the center and you can see how everything moves around it (edited)
<discord->
egg. — well, no, *all five* Lagrange points would be fixed in such a frame
<discord->
egg. — they would not really be in the centre though
<discord->
egg. — but they would not move
<discord->
egg. — (nor would the two massive bodies)
<discord->
Zeusbeer. — sicc
<discord->
egg. — just look it up
<discord->
Damien. — @egg do you have any WIP implantation of such a frame or is it purely theoretical at this point?
<discord->
DanieI. — halo orbits are what lagrange points look like in secondary centred orbit right
<discord->
Damien. — @egg do you have any WIP implementation of such a frame or is it purely theoretical at this point? (edited)
<discord->
egg. — @Damien this is largely theoretical, because there are fundamental obstacles to implementing that given the way the libraries are structured
<discord->
egg. — and there are more amusing things to do
<discord->
egg. — and cats to pet
<discord->
Damien. — @DanieI you can see the orbit around the Lagrange point in the child centred parent aligned frame yes
<discord->
egg. — yeah, ultimately it is not too far off from the rotating-pulsating frame
<discord->
egg. — unless the main bodies are in a very eccentric orbit
<discord->
Zeusbeer. — what is the biggest thing getting added to principia in the future?
<discord->
egg. — dealing with 2400 sounds big
<discord->
egg. — will take a while
<discord->
Zeusbeer. — 2400? Bugs?
<discord->
egg. — saves being big and slow
<discord->
egg. — (the solution will be to be clever in the way we store the past)
<discord->
Damien. — @Zeusbeer @egg will say it's working on save history size but we all know that the orbiter-lander bug is the highest priority
<discord->
Damien. — We're just waiting on nasa supercomputer time
<discord->
Zeusbeer. — how is the orbiter lander bug such a high priority?
<discord->
egg. — no, this is a recurring joke
<discord->
Zeusbeer. — xdd
<discord->
egg. — it is not actually a priority
<discord->
Zeusbeer. — I'm personally fixing the big save file problem getting a new ssd in the future
<discord->
Zeusbeer. — )))
<discord->
egg. — that will fix the size issue, but not the time issue
<discord->
egg. — KSP is stupidly slow when it deals with large saves, and there is also the recomputation of solar system history which can take a while if you are in the 200s
<discord->
DanieI. — so is it impossible to get a still lagrange point without a pulsating frame
<discord->
egg. — KSP is stupidly slow when it deals with large saves, and there is also the recomputation of solar system history which can take a while if you are in the 2000s (edited)
<discord->
egg. — indeed
<discord->
egg. — the Lagrange points will be moving a little bit
<discord->
Zeusbeer. — ;-;\
<discord->
Zeusbeer. — ;-; (edited)
<discord->
egg. — less so than the non-fixed planet though
<discord->
Zeusbeer. — wait if principia is multi threaded
<discord->
egg. — so in most situations it’s close enough
<discord->
Zeusbeer. — the slowness is fixed by just getting a threadripper cpu
<discord->
Zeusbeer. — smile
<discord->
Butcher. — > @Butcher did you manage to rebuild the thing with your fix?
<discord->
Butcher. — @egg yes but untested.
<discord->
DanieI. — what if you store history in separate files
<discord->
DanieI. — at least for the planets
<discord->
egg. — then we have boring software engineering problems: making sure we maintain a mapping from the saves to the separately-stored cached histories, somehow garbage-collecting the histories so we don’t fill your disks with every save, your save is no longer self-contained so you can’t share it or send it on its own for a bug report
<discord->
egg. — instead we can have interesting astronomy and numerics problems
<discord->
DanieI. — hmm
<discord->
DanieI. — store them as patched conic segments?
<discord->
Butcher. — As an aside, what's the best way to get to say L4?
<discord->
DanieI. — nbody approximates to conics so you could split an nbody trajectory into a series of conics could you not
<discord->
DanieI. — and any conic can be uniquely defined by 5 points
<discord->
DanieI. — im not an astronomist, just a boring software engineer
<discord->
egg. — this is not too far from the general idea behind what we are doing (but the specifics don’t work). The idea is that, with the scheme we use (splines downsampled until they have the right accuracy), the costliest saves (the ones that need short polynomials) are the ones on the most boring trajectories (low orbits, which are not very perturbed)
<discord->
egg. — so the idea is indeed to have something which is good at representing orbits
<discord->
egg. — orbits, as in, highly-periodic trajectories
<discord->
egg. — and then it turns out that astronomers have come up with good representations for those, using what they call Poisson series
<discord->
DanieI. — Your work is so cool
<discord->
Zeusbeer. — yes
<discord->
Zeusbeer. — shame not alot of people actively play with principia
<discord->
Zeusbeer. — maybe I could make a tutorial series on doing basic stuff in ksp but with principia
<discord->
Zeusbeer. — but first I need to get perfect with it
<discord->
Zeusbeer. — and I still struggle doing gravity assists properly ;-;
<discord->
DanieI. — it's all about bending your trajectory
<discord->
DanieI. — Turn that pesky normal relative velocity into useful parent prograde
<discord->
egg. — @Butcher I would say eyeball and feeling for the gravitational field with the flight plan
<discord->
egg. — not a very satisfactory answer admittedly
<discord->
Zeusbeer. — there's a tutorial on it, but I suppose you already know how to do it
<discord->
egg. — but L4 is at least easy to spot by eye, being the third vertex of the equilateral triangle in the reference plane whose other two are the two bodies
<discord->
Butcher. — Is it normal to fly towards it and ballistic capture or to burn near the point to capture?
<discord->
Zeusbeer. — you can use a geometric tryangle to get the 60 degree angle needed
<discord->
Zeusbeer. — 😉
<discord->
Zeusbeer. — you can use a geometric triangle to get the 60 degree angle needed (edited)
<discord->
egg. — @Butcher hmm. I don’t think you can ballistic capture into that ? But I don’t know
<discord->
DanieI. — first time i used principia it was true
<discord->
DanieI. — cantor i believe?
<discord->
Zeusbeer. — I was just about to say that ^^^^
<discord->
DanieI. — this mod has grown so much im in love with it
<discord->
Zeusbeer. — it's turning easier than stock for some things
<discord->
Zeusbeer. — making me prefer principia over a normal stock install for missions
<discord->
Butcher. — Protractor is the semi circle one, triangle is a set square.
<discord->
DanieI. — barycenter centric is still best frame for l4, l5 and l3 right
<discord->
Zeusbeer. — Btw
<discord->
Zeusbeer. — I love the "random user comments" on the faq page
<discord->
egg. — updated
<discord->
Zeusbeer. — "I'd like the planets to follow their stock orbits"
<discord->
Zeusbeer. — lol
<discord->
Zeusbeer. — and "I'm using a custom solar system mod, why isn't it stable?
<discord->
Zeusbeer. — It all depends on whether your system was sanely designed. If it has 50 Duna-sized planets orbiting a Jool-sized body, many of these are going to interplanetary space today."
<discord->
egg. — @Butcher isn’t a set square any right-angled tool, regardless of containing markings for arbitrary angles inside ?
<discord->
Butcher. — Yes
<discord->
egg. — so I guess this is a combination protractor and set square
<discord->
Butcher. — There isn't a specific name for those with markings AFAIK.
<discord->
egg. — same in French tbh, this works as an équerre and rapporteur
<discord->
Butcher. — I mostly use a combination square.
<discord->
Zeusbeer. — protractor is actually the incorrect word for what I sent earlier
<discord->
DanieI. — or should I use body centric parent fixed
<discord->
Zeusbeer. — it's geo-triangle
<discord->
Butcher. — Is that not what I said? Protractor is semi circular.
<discord->
egg. — (why does it not have an English article)
<discord->
egg. — well it has no English article
<discord->
Damien. — @Butcher it depends on your orbit. If it's in plane with the moon-earth line then it will be occluded at least some of the time but it's a function of the size and shape of the orbit
<discord->
Damien. — An inclined orbit can be set to be never occluded
<discord->
Butcher. — I guess if you have a fairly loose orbit you will tend not to be occluded so much.
<discord->
Damien. — Yeah practically it's not an issue
<discord->
Butcher. — Not that I'm doing far side stuff yet, but it could be useful.
<kmath>
YouTube - Kerbal Space Program - Principia | Mun Lagrange Point L4 | Real Physics in KSP
<discord->
Zeusbeer. — Is it hard to get into solar-kerbin l1?
<discord->
Damien. — Not really no
<discord->
Damien. — Eject radially towards the sun with the right velocity and play with it until it loops
<discord->
Zeusbeer. — I see yes
<discord->
DanieI. — so is barycentric fixed best for l4, l5, and l3
<discord->
Damien. — Having some angle between your ejection direction and the sun can help because you'll loop to the side of the L point and slide into it
<discord->
Damien. — @DanieI No use child centred parent fixed
<discord->
Zeusbeer. — Solar l1 stable or not?
<discord->
siimav. — I submitted a PR to LGG to fix the airlaunch issue with Principia:
<discord->
Damien. — @DanieI I'm extremely mathematically challenged but this oval shaped lunatic here has had me reading astrodynamics research papers. for fun.
<discord->
DanieI. — can you pass them here
<discord->
DanieI. — id like to know what the hell is going on
<discord->
Damien. — do a search in here for files, pdfs if you can be that specific in searches
<discord->
egg. — see, J3 is clearly eggness
<discord->
egg. — (bottom-heaviness)
<discord->
Damien. — pretty much everything discussed here has been discussed before and will again
<discord->
Damien. — by 'read astrodynamics papers' I do mean 'kinda understand the diagrams maybe' admittedly
<discord->
DanieI. — i know math
<discord->
DanieI. — kinda
<discord->
Damien. — I know I've got a load of them saved on a hdd currently disconnected after a system reinstall
<discord->
Damien. — I'll get them together when I get time
<discord->
Damien. — they're mainly about weird low energy transfers
<discord->
Damien. — I've also got a copy of that michael capderou book egg loves that costs 💰
<discord->
DanieI. — horseshoe orbits confuse me
<discord->
Butcher. — What if the earth is actually a gömböc?
<discord->
Butcher. — @Damien I got as far as orbital guidance papers and then my brain was full.
<discord->
DanieI. — i want to understand periodic orbital peturbation
<discord->
egg. — then I recommend the relevant chapter of the Capderou book
<discord->
DanieI. — why does the moon cause vertical perturbations in a geostationary orbit
<discord->
DanieI. — how is still stable
<discord->
DanieI. — how is it still stable (edited)
<discord->
egg. — Chapter 6, *Satellite en orbite réelle (perturbée)*
<discord->
egg. — I can’t really summarize that usefully I’m afraid
<discord->
DanieI. — i will read
<discord->
DanieI. — first to learn french
<discord->
egg. — there is an English translation of that book
<discord->
Damien. — @DanieI moon above equator - satellite go up. Moon below equator - satellite go down