egg changed the topic of #principia to: READ THE FAQ: http://goo.gl/gMZF9H; The current version is Cardano. We currently target 1.2.2. <scott_manley> anyone that doubts the wisdom of retrograde bop needs to get the hell out | https://xkcd.com/323/
<UmbralRaptor>
I'm moderately certain that the sun doesn't have enough energy available to do this.
<UmbralRaptor>
er, wait. Maybe I thought through it wrong. Just need to fuse/expel 1.5 to 3.5% of the sun's mass.
<UmbralRaptor>
!wa mass of jupiter / mass of sun
<Qboid>
UmbralRaptor: M_♃/M_☉ (Jupiter mass per solar mass): 9.5458×10^-4
<UmbralRaptor>
Yep, there's not enough material in solar system to drop pellets on the sun.
<egg>
UmbralRaptor: but I don't think it's the pellets that you use as reaction mass
<egg>
it's the sun
<egg>
you use the pellets to somehow make the sun asymmetric and have it shove you in the right direction
<UmbralRaptor>
Well, if you're blowing off chunks of the sun, you'll get stuck with much lower Ve...
<egg>
depends how much you block off...
<UmbralRaptor>
Maybe there's a useful tradeoff to maximize momentum for energy?
<UmbralRaptor>
egg: What, like a shkadov thruster?
<egg>
UmbralRaptor: pretty much
<UmbralRaptor>
(2500 years imposes strict limits if you're trying to move an entire star around.)
<egg>
hmm
<egg>
UmbralRaptor: yeah, so then just blow off bits of sun
<egg>
not too much
<UmbralRaptor>
If I had half a million years, this would be way easier.
<UmbralRaptor>
(Yep, the #kspacademia is leaking)
<egg>
GregroxMun: how goes the TRAPPIST
<GregroxMun>
Not much, I've been talking with my mother about irl stuff for the past many minutes
<GregroxMun>
Definitely going to want to put some asteroids and asteroid belts in the system. Partially to add some early-career destinations and partially to add fueling stops.
<GregroxMun>
A couple of asteroids should be able to be placed in the main inner system, and then a couple of big icy lumps further out. A couple comets, a couple KBO-type things. Maybe a few dwarf planets.
<GregroxMun>
Things which don't exist in the real TRAPPIST-1 as far as observations suggest, but which aren't unlikely to be there.
<egg>
not sure they'd be stable in that mess
<egg>
twould be interesting
<GregroxMun>
I tried to model it in US^2 but the system falls apart anyway.
<egg>
uh
<egg>
that's odd
<GregroxMun>
yes it is.
<egg>
they tend to do things right
<egg>
did you screw up typing a number
<egg>
that can happen
<GregroxMun>
It's worth noting that it's possible I did my calculations for TRAPPIST-1 wrong.
<GregroxMun>
I define surface gravity and radius in the config.
<GregroxMun>
172 gee is what I have. But this isn't that surprising because it's Jupiter-like radius but many times more massive.
<egg>
uuuh
<GregroxMun>
wait no.
<GregroxMun>
Shit.
<GregroxMun>
That's not right is it.
<egg>
GregroxMun: it's less than the sun's
<egg>
irl
<egg>
yours is an order of magnitude too big
<egg>
it's pretty much just 10x too big
<GregroxMun>
Oh damn I really screwed that up big time.
<egg|zzz|egg>
GregroxMun: ah, yes, forcing axial tilt with principia is hard
<egg|zzz|egg>
GregroxMun: the initial state will have to be tuned to get the correct periods
<GregroxMun>
axial tilt?
<egg|zzz|egg>
s/axial tilt/tidal locking/
<Qboid>
egg|zzz|egg meant to say: GregroxMun: ah, yes, forcing tidal locking with principia is hard
<egg|zzz|egg>
brain no worky
<egg|zzz|egg>
it's ten to three
<GregroxMun>
fair enough.
<GregroxMun>
:)
<egg|zzz|egg>
so yeah, the rotation is off, which means that the period is wrong, which means that manual tuning needs to be done until the period is right
<egg|zzz|egg>
this is hard
<egg|zzz|egg>
and I don't have a good answer for it aside from "try nudging the sma repeatedly"
<egg|zzz|egg>
start from the inner planets
<egg|zzz|egg>
I mean this could be done programmatically I guess but that's also differently tedious, maybe you can find something decent by hand
<egg|zzz|egg>
see whether the planet orbits too fast or too slow, correct, retry
<GregroxMun>
Wouldn't the planet still get out of lock by perterbations from the other planets?
<egg|zzz|egg>
GregroxMun: that's the thing, you need to take that into account
<egg|zzz|egg>
so that on average over many years it's the right period
<egg|zzz|egg>
you need an average period
<egg|zzz|egg>
KSP doesn't do that, we do slightly better but we don't really do that either
<egg|zzz|egg>
GregroxMun: and US2 probably doesn't do that, so that may explain thing, you may have encountered the same thing
<GregroxMun>
I'm fairly certain US2 does something to preserve tidal locks.
<egg|zzz|egg>
that's not the question
<egg|zzz|egg>
it may have tides
<egg|zzz|egg>
but the initial state doesn't yield the right average periods
<egg|zzz|egg>
the tidal locking is cosmetic, it's just a witness to a real problem with the periods
<egg|zzz|egg>
if the orbital periods are wrong the system doesn't have the dynamical properties of the real one
<egg|zzz|egg>
and the periods you want are the average ones
<egg|zzz|egg>
setting the average period is hard, because, well, you have to average :-p
<egg|zzz|egg>
but it's the one that matters
<egg|zzz|egg>
not the osculating period
<egg|zzz|egg>
the osculating period is just a clumsy way of giving a position and a velocity
<egg|zzz|egg>
but it doesn't describe any actual orbit in a real-life system
<egg|zzz|egg>
that osculating orbit keeps changing
<egg|zzz|egg>
because real life isn't Kepler
<egg|zzz|egg>
it's close enough, so there is *some* orbit that approximates
<egg|zzz|egg>
but it's hard to set the initial state so that the actual orbit is approximated by the desired conic
<egg|zzz|egg>
maybe I'll look into that but it sounds like a lot of work
<GregroxMun>
I have another system that I'm sure has at least one point of near certain apocalypse.
<GregroxMun>
I haven't tried it in an N-Body simulation yet.
<lamont>
well i got the deps built on my mac
<egg|phone|egg>
Nice ! But Zzzzzz?
<lamont>
ah, `make` explodes in a nice fire though
<egg|phone|egg>
Hah
<egg|phone|egg>
Is it warm at least
<egg|phone|egg>
Lamont: make an_apple_pie
<lamont>
i’m been dealing with jenkins fires all day at work, so this is a pretty seamless transition really...
icefire has quit [Read error: -0x1: UNKNOWN ERROR CODE (0001)]
Jesin has joined #principia
sdrodge has quit [Ping timeout: 200 seconds]
sdrodge has joined #principia
MrSavage has quit [Read error: Connection reset by peer]
Bigcheese has quit [Read error: Connection reset by peer]
Bigcheese has joined #principia
Rokker is now known as RokkerSleep
Jesin has quit [Ping timeout: 180 seconds]
Wetmelon has quit [Ping timeout: 206 seconds]
ferram4 has quit [Ping timeout: 200 seconds]
maccollo has quit [Quit: Web client closed]
maccollo has joined #principia
<egg|zzz|egg>
!wpn maccollo
* Qboid
gives maccollo a Helmholtz cohomology
<egg|zzz|egg>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor a radio base
<GH>
[Principia] eggrobin opened pull request #1295: Correctly read the NavigationFrameParameters in the ReferenceFrameSelector (master...1293) https://git.io/vS3X7
<GH>
[Principia] pleroy commented on issue #1293: The fix will be in Cartan, to be released around the new moon of April. In the meantime, don't use the reference frame fixing the centre of a celestial and the line towards another celestial (e.g. Earth-Centred Sun-Aligned, ECSA). https://git.io/vS37g
Thomas|AWAY is now known as Thomas
<GH>
[Principia] eggrobin commented on issue #1293: More specifically, don't use this frame for manœuvres, and don't create a manœuvre when this frame is selected as the plotting frame. Using it as a plotting frame is otherwise fine. https://git.io/vS35D
<maccollo>
hmmm
<maccollo>
tried to have ago at sending a probe to duna again
<maccollo>
but when I leave kerbin SOI I crash into the sun
<egg|zzz|egg>
that's odd O_o
<egg|zzz|egg>
I'll have to try doing that, I don't think I tried it
<egg|zzz|egg>
well I did try it in RSS, I flew to venus
<egg|zzz|egg>
this is all very odd
<maccollo>
made a quick save this time
<maccollo>
so far it happened twice in a row
<egg|zzz|egg>
hm
<maccollo>
time warping across the SOI boundry fast appears to be the the only way to consistently trigger it
<egg|zzz|egg>
hmm
<egg|zzz|egg>
what is KSP doing to me again >_>
<maccollo>
yeah, that appears to be it
<maccollo>
warping at a slower rate so the automatic slowdown mechanic has enough time to step down the warp gets me past the soi change without problem
<egg|zzz|egg>
maccollo: I think we disable the automatic slowdown mechanic
<egg|zzz|egg>
the idea being that (unless KSP does screwy things to us, which it may well do), we know the position of everything regardles of SOI, and can tell KSP about it no matter what happened SOI-wise
<egg|zzz|egg>
I'll have to look into that bug
<egg|zzz|egg>
maccollo: can you open an issue, add as much reproduction steps as you can, ideally a save (with stock parts would be best)
RokkerSleep is now known as Rokker
<maccollo>
gonna try to play around with it a bit more
<maccollo>
no crash when entering duna's SOI at high warp
<egg>
good news! :D
<maccollo>
is it really? Wouldn't be better if it was super easy to replicate?
<maccollo>
anyway, just gonna test escaping from duna at high warp aswell
<maccollo>
no crash
<egg>
maccollo: well, good news from the gameplay sense :-p
<maccollo>
hmm
<maccollo>
it seems the game slowdown mechanic overpoweres my attempt to keep the warp factor at maximum
<maccollo>
is there a way to disable it?
<egg>
maccollo: the slowdown on SOI change? I thought we disabled that
<egg>
maccollo: or do you mean the slowdown at low altitudes
<maccollo>
slowdown from SOI change is still active
<egg>
maccollo: is there something spamming in the INFO log?
<egg>
try Cardano first, it's possible that we broke the clang build since then
<egg>
lamont: if that doesn't work, maybe clang on mac has a different opinion of what's legal; strange things can happen :-p
<lamont>
mac clang is different
<egg>
hah
<egg>
yeah
<lamont>
but it looks like it should be based off of 3.9.0 and should fully implement c++14
<lamont>
ah, cardano tag works better
<egg>
yeah, we may have broken the build in 2 days :D
<lamont>
w00t
ferram4 has joined #principia
<maccollo>
don't see any spam about warp
<egg>
that's odd...
<egg>
maccollo: any other mods installed?
<maccollo>
only KER and a few visual mods
<egg>
hmm
<maccollo>
there we go!
<maccollo>
crash
<maccollo>
only managed to trigger it once though
<egg>
blarg
<egg>
well, I know it's there, maybe I'll look into it, but don't waste too much time on it I guess
<teabot>
Wastea.
<egg>
yes teabot
<maccollo>
it's actually kind of tricky, because I have to somehow get an increase warp command in there between where the game slows down and the crossing of the SOI
<egg>
it's very odd that it slows down
<egg>
I disabled it...
<egg>
maccollo: can you send me your INFO log?
<maccollo>
sure
<maccollo>
you know what I am getting though?
<maccollo>
well, maybe it doesn't say much
<maccollo>
but it says reinstating stock gravity
<maccollo>
right where the vessel is destroyed
<egg>
yeah, that means you no longer have an active vessel packed in space
<GH>
[Principia] eggrobin opened pull request #1296: Use Trajectory in BodyCentredBodyDirectionDynamicFrame (master...evaluate-discrete) https://git.io/vSsQu
Wetmelon has quit [Ping timeout: 206 seconds]
ferram4 has joined #principia
<egg>
maccollo: nice duna approach btw :D
<egg>
unfortunate control issues after reentry :-p
<egg>
maccollo: feel free to make more of these n-body videos, it's nice to see it in practice
<egg>
(though maybe next time try not to crash :-p)
HypergolicSkunk has joined #principia
technicalfool has joined #principia
maccollo has quit [Quit: Web client closed]
ferram4_ has joined #principia
ferram4 has quit [Read error: -0x1: UNKNOWN ERROR CODE (0001)]
regex has quit [Remote host closed the connection]
GregroxMun has joined #principia
<GregroxMun>
o/
<UmbralRaptor>
\o
<GregroxMun>
For the principia patch for HSoC, I'll probably have to adjust the orbits of the Drurian moons. The culprit is the large ocean moon Eckel.
<egg|phone|egg>
?
MrSavage has joined #principia
<GregroxMun>
I don't actually have a good link for HSoC so I can't give an answer to that ?
<GregroxMun>
it's a planet mod that I've been working on since ~October off and on
<GregroxMun>
A classical planetary system for the most part.