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
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<discord->
scimas. — An improvement (at least seems like an improvement for now) request similar to the delete flight plan request: Can the rebase extend the flight plan till the same timestamp rather than the same flight plan duration? For example, consider a 3 manoeuvre, 4 day duration flight plan. The first manoeuvre is only a couple minutes or so in the future, 2nd is 3d 22h in the future and 3rd is 3d 23h in the f
<discord->
egg. — I suspect you are timing out instead of reaching your desired final time
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<discord->
scimas. — It wasn't timing out, but I'm fairly certain that the flight plan length was far longer after the second rebase that I'd expect. I will check again tomorrow (later today, actually).
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<discord->
lamont. — @egg how do you do strongly typed vectors and reference frames in principia?
<discord->
egg. — like the quantities, template magic
<discord->
egg. — instead of being templatized on the exponents for mksA etc. the multivectors are templatized on their rank (vector vs. bivector) and frame
<discord->
egg. — each frame is a distinct type wherein we shove some known properties (is it inertial? does it rotate? what is its handedness? etc.)
<discord->
egg. — and then we have a host of compile-time checks accordingly: you cannot construct a rotation that converts vectors in F1 to vectors in F2 if F1 and F2 differ in handedness, you can only talk about Kepler orbits if your coordinates are nonrotating, etc.
<discord->
lamont. — yeah i'm going to have to look at this tomorrow, too late, too tired.
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<_whitenotifier-9244>
[Principia] eggrobin opened pull request #2654: Accept other Visual Studio versions, except when releasing - https://git.io/JJ8FX
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<discord->
Ripper2900. — Geez that video is nice! It must take forever to make those. I just spent ~5 hours even just _plotting_ a trajectory to Mars, and even that was not good enough to not require a 280 m/s adjustment down the trajectory.
<discord->
Ripper2900. — How DO ppl do these transfers? Is it also an all-nighter?
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<discord->
Zeusbeer. — Is reach even on this discord? Or is he just flexing on us mortals outside here?
<discord->
Zeusbeer. — @Ripper2900 how does it take you 5 hours? For me its like 15 minutes at most with the right launch window
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<discord->
Zeusbeer. — Egg? If you recreate a real life mission, is it plausible to launch at the exact same date as in real life in RSS?
<discord->
egg. — yes, things should be where they are in real life if you use Principia
<discord->
egg. — (if you don’t they won’t ; for instance the motion of the Moon is highly perturbed so there is no way to make it accurate without Principia)
<discord->
Zeusbeer. — Yes, I'll try to reacreate new horizons' flight plan then
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<discord->
Zeusbeer. — Why did he only upload on chinatube?
<discord->
egg. — he used to only do videos there, and started using YouTube later on
<discord->
Zeusbeer. — Interesting
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<discord->
Zeusbeer. — would the standard huge antenna with SMURFF be enough for communications with earth
<discord->
Zeusbeer. — would the standard huge antenna with SMURFF be enough for communications with earth? (edited)
<discord->
Zeusbeer. — would the standard huge antenna with SMURFF be enough for communications with earth from pluto system? (edited)
<discord->
Anomaly. — Wrong channel?
<discord->
Zeusbeer. — yes excuse me
<discord->
Butcher. — I'm liking solid lines for planning.
<_whitenotifier-9244>
[Principia] pleroy edited pull request #2654: Accept other Visual Studio versions, except when releasing - https://git.io/JJ8FX
<discord->
Butcher. — @egg would having this configurable be something you'd be interested in?
<discord->
egg. — I need to think about it
<discord->
Ripper2900. — @Zeusbeer well, obviously I'm not using the right tools here... Or methodology. Any hints?
<discord->
Ripper2900. — I was trying MJs transfer planner to give me a hint as to the general maneuver, but entering those values in principia didn't give nearly a goodish encounter, so tweaking resetting, trying other planners, game crashing etc. I took hours!
<discord->
Zeusbeer. — for simplicity, I like using kerbal alarm clock for roughly the right times for transfer, where you can plan an alarm for a launch window
<discord->
Zeusbeer. — it's not perfectly accurate, but works most of the time
<discord->
Zeusbeer. — then for the manouver, just do the normal high prograde/tangent burn till sun orbit, then switch the a sun centered view and look if it's close to the target bodies orbit
<discord->
Zeusbeer. — say Mars is your target body, switch to Mars and the bottom frame of reference
<discord->
Zeusbeer. — then go from a topdown view of mars and get 1 of the planner lines to go perfectly trough mars
<discord->
Zeusbeer. — after that you can plan a mid-course correction with binormal (radial in stock I think, the purple one) to lower the closest approach
<discord->
Zeusbeer. — with the right launch window, you should be able to get really close with just using prograde and time changes
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<discord->
Butcher. — Can you tell what the plan is for?
<discord->
Damien. — geosat phasing?
<discord->
Butcher. — Bingo.
<discord->
Zeusbeer. — your getting her into a liberation point?
<discord->
Butcher. — In hindsight I should have done my GTO at the ascending node instead of descending as that would have put me much closer sooner.
<discord->
Butcher. — I'm getting it to approximately over KSC.
<discord->
Butcher. — By KSC I mean Vandenburg.
<discord->
Zeusbeer. — I really dislike new rule one, let me react with single word comments 😦
<discord->
Butcher. — I'll probably try to sit it at the 104.9W stable point.
<discord->
Damien. — I doubt the odd one word reply is a crime so long as it's not a pattern
<discord->
Butcher. — As that's approximately correct for west coast N America. This thing has quite a wide cone anyway.
<discord->
Damien. — also this channel is a lot more casual
<discord->
Butcher. — Single word replies as an occasional thing isn;t an issue - we had problems with people only typing 1-2 word replies for like 20 messages straight.
<discord->
Damien. — yeah if your reply is one word, fine. if it's 10 words on 10 lines then no
<discord->
Butcher. — Sat is now on RCS for final orbit tweaking, so I only have 202 m/s to play with.
<discord->
Zeusbeer. — geostationary sats are so much easier to do with principia
<discord->
Zeusbeer. — stock is actually a joke
<discord->
Zeusbeer. — It's just annoying that principia eats up my pc in RSS
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<discord->
egg. — @Damien yes, in particular wrt rule #7 it should be understood that pictures of cats on astronomy papers & textbooks are on-topic for this channel :-p
<_whitenotifier-9244>
[Principia] eggrobin synchronize pull request #2654: Accept other Visual Studio versions, except when releasing - https://git.io/JJ8FX
<discord->
Butcher. — Sorry my cats just keep throwing themselves in their food bowls and such. No textbooks.
<discord->
Zeusbeer. — so how do you do this practically? is there an ingame menu?
<discord->
DRVeyl. — Egg, is that integration paid each time a save loads? Not on scene switch, I imagine.
<discord->
DRVeyl. — And can you extract an initial state config? Ie current start, warp to some point, then ask principia "if I want to start right now, what should my state look like?" ... Or is it trivial to just go to JPL?
<_whitenotifier-9244>
[Principia] eggrobin synchronize pull request #2654: Accept other Visual Studio versions, except when releasing - https://git.io/JJ8FX
<discord->
egg. — @DRVeyl scene switch is a save load. We have some tooling to build an initial state from JPL data; building tooling to do what you suggest would be actual work so let’s not go there.
<discord->
Zeusbeer. — where do you change "solar_system_epoch" ?
<discord->
egg. — @Zeusbeer changing it without changing the corresponding data is meaningless; it is the timestamp of the initial positions and velocities used by Principia.
<discord->
Zeusbeer. — so it's basically impossible to do?
<discord->
egg. — fetching the data from JPL by email is very tedious, but we have fetched things at various points in time already; creating cfgs from that simply requires building the principia tools
<discord->
Zeusbeer. — because I feel my ryzen 2600 isn't enough for any work outside of the 4 inner planets (edited)
<discord->
Zeusbeer. — maybe I need to increase the step size
<discord->
Butcher. — i7-8565U
<discord->
Butcher. — This thing is not really fast enough.
<discord->
egg. — i7 920
<discord->
egg. — i7 920 on my Zürich desktop (edited)
<discord->
egg. — i7-6600U on my laptop
<discord->
Butcher. — When I'm back in the office I'll be on a 2950X.
<discord->
egg. — i7-6600U on my laptop (that one does not like running RSS) (edited)
<discord->
Butcher. — Bigger bonus there though is 64GB ram. That really helps with RSS>
<discord->
Butcher. — Bigger bonus there though is 64GB ram. That really helps with RSS. (edited)
<discord->
Zeusbeer. — I just use all my lifes savings and buy a 3950x lmao
<discord->
egg. — a xeon phi, to integrate all your vessels in parallel 🙃
<discord->
Zeusbeer. — might aswell steal a supercomputer at that point
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<discord->
DRVeyl. — > scene switch is a save load
<discord->
DRVeyl. — That doesn't seem right. It also can come with a shortcut that time doesn't change from one scene to the next, so your state when you exit a scene is the same as when you enter the next.
<discord->
DRVeyl. —
<discord->
DRVeyl. — Tho if the computation just for the bodies isn't actually expensive, then I suppose it doesn't matter. I don't know how much time scene switches take in principia when UT is large.
<discord->
DRVeyl. — > scene switch is a save load
<discord->
DRVeyl. — That doesn't seem right. It also can come with a shortcut that time doesn't change from one scene to the next, so your state when you exit a scene is the same as when you enter the next.
<discord->
DRVeyl. —
<discord->
DRVeyl. — Tho if the computation just for the bodies isn't actually expensive, then I suppose it doesn't matter. I don't know how much (additional) time scene switches take from principia when UT is large. (edited)
<discord->
Zeusbeer. — had a jupiter encounter and was tweaking it to get to pluto and then BSOD
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<_whitenotifier-9244>
[Principia] pleroy labeled pull request #2654: Accept other Visual Studio versions, except when releasing - https://git.io/JJ8FX
<discord->
egg. — @DRVeyl the goal as part of 2400 is to save the ephemeris instead of recomputing it. Right now this is infeasible because the ephemeris is big (and in ksp saves big is slow, but here this is so big that it ooms on naive save anyway)
<discord->
egg. — The first step in 2400 is thus to make things smaller by orders of magnitude
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<discord->
scimas. — @egg Can confirm that my report wasn't false. The rebase does preserve the flight plan duration rather than flight plan end timestamp, I have fresh screenshots
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<discord->
scimas. — After 2nd manoeuvre execution, but before rebase
<discord->
scimas. — Yeah, the code egg linked to me does seem to have the intention of preserving the end time rather than duration, but it just isn't working like that.
<discord->
Zeusbeer. — Rebase is for if you failed a manouver right?
<discord->
DRVeyl. — Understand. Wasn't so much asking about 2400. More your comment about being at, or starting at, a future time. If there isn't a noticable performance cost to playing eg 30 years after epoch in general, it definitely doesn't matter.
<discord->
Stonesmile. — @Zeusbeer rebase deletes past time and recalculates the prediction from the new initial state
<discord->
Zeusbeer. — Cool
<discord->
Butcher. — Rebase is very useful.
<discord->
scimas. — @Zeusbeer You're always going to "fail" to execute manoeuvres perfectly, that kind of control just isn't available. Rebase is "I know my execution wasn't perfect, so the rest of the flight plan is technically invalid. But I'm going to want to perform similar manoeuvres anyway, so discard the current prediction, recalculate it based on the current state of the vessel and add the manoeuvres on top of
<discord->
Zeusbeer. — ))))))
<discord->
Zeusbeer. — so if you have like 2 manouvers ready
<discord->
Zeusbeer. — and you slightly miss the first one, you hit rebase and the second manouver should calculate again on the current flight plan?
<discord->
scimas. — Yes, the manoeuvres will have the exact same dV values and the flight plan will change accordingly.
<discord->
egg. — > Understand. Wasn't so much asking about 2400. More your comment about being at, or starting at, a future time. If there isn't a noticable performance cost to playing eg 30 years after epoch in general, it definitely doesn't matter.
<discord->
egg. — @DRVeyl there is a noticeable cost unfortunately (because recomputing 30 years of solar system can take a few seconds)
<discord->
DRVeyl. — Ok. Will file it away, not an important issue currently as don't think there's a lot of Principia users playing games that far from epoch. (There's barely any RP-1 folks at least). Pap is making his way back and we've started talking about configurable game starts tentatively again. So might *eventually* be something to address.
<discord->
DRVeyl. — Also depends on the definition of "a few" there. ;)
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<discord->
egg. — @DRVeyl there is nothing to file, it is a known issue, it is part of 2400
<discord->
egg. — the start is configurable trivially by toying with `game_epoch`, the performance cost is 2400
<discord->
DRVeyl. — I keep reading 2400 as being about vessel histories, and not CelestialBody histories, but I see how solving it for vessels might also solve it for CBs. Not sure why that escaped me before.
<discord->
egg. — yeah it was originally about vessel histories, but we realized that it is the same problem
<discord->
egg. — (although those are currently implemented very differently, they should both fit in the shiny new world of Poisson series)
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<_whitenotifier-9244>
[Principia] scimas opened issue #2655: Flight plan rebase preserves plan duration instead of plan end time - https://git.io/JJ4uL
<discord->
lamont. — @egg so a general reference frame at a moment in time -- ignoring handedness -- can be defined by a transform (rotation plus translation plus scaling)
<discord->
egg. — No, you need it's derivative too
<discord->
egg. — Its
<discord->
egg. — Stupid phone
<discord->
lamont. — well you need the time evolution in general right for non-inertial frames?
<discord->
egg. — Yes but only the first derivative matters to transform instantaneous properties
<discord->
egg. — We call that RigidMotion
<discord->
egg. — And transform we call RigidTransformation
<discord->
lamont. — derivative needs to be smooth?
<discord->
lamont. — well, no derivative needs to be continuous?
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<discord->
egg. — [AFK a bit, will eggsplain later]
<discord->
Zeusbeer. — it's actually a joke how much Jupiter can just swing spacecrafts away
<discord->
Zeusbeer. — is principia in UTC?
<discord->
Zeusbeer. — is principia in UTC timezone? (edited)
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<discord->
Falcon. — anyone here know what the orbital velocity around Pluto is?
<discord->
Zeusbeer. — If it was easy to change the dates, my "new horizons" would be doing the actual new horizons mission instead of flying by jupiter to go to saturn like pioneer in 1973 (((
<discord->
itsRyan. — @Falcon It would depend on what the orbit looked like. One possible orbit is Charon at 210 m/s.
<discord->
Falcon. — if i was at 200 km above Plutos orbit, what would it be?
<discord->
scimas. — Look up Pluto's mass and radius, then calculating orbital speed is trivial with the vis-viva equation
<discord->
Zeusbeer. — Wow, I can slingshot from Saturn and go to Uranus aswell ❤️
<discord->
Falcon. — @scimas you can check me, but i got 800ish m/s at a 200 km orbit
<discord->
Falcon. — escape velocity of Pluto according to wiki is about 1.212 km/s
<_whitenotifier-9244>
[Principia] eggrobin labeled issue #2655: Flight plan rebase preserves plan duration instead of plan end time - https://git.io/JJ4uL
<_whitenotifier-9244>
[Principia] eggrobin assigned issue #2655: Flight plan rebase preserves plan duration instead of plan end time - https://git.io/JJ4uL
<discord->
itsRyan. — The relevant equation is V=sqrt(GM/r). G is the gravitational constant, M is the sum of both masses, r is the radius of the orbit (remember to add the radius of the body).
<discord->
itsRyan. — Yes, about 790 m/s for 200km+1180km
<discord->
itsRyan. — Yes, about 793.3 m/s for 200km+1180km (edited)
<discord->
Falcon. — yeah im trying to plan an orbiter... and it seems like 4 km/s is the optimal injection velocity for travel time compared to amount of fuel savings
<discord->
Falcon. — its about a 24 year trip to get something out there to burn about 3200 m/s to get into orbit
<discord->
Falcon. — that is with a Jupiter gravity assist