raptop changed the topic of #principia to: READ THE FAQ: http://goo.gl/gMZF9H; The current version is Fréchet. We currently target 1.5.1, 1.6.1, and 1.7.x. <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-_>
Sage. — will mechjeb perform manoeuvres made using the flight planner?
<discord-_>
lpg. — not in any helpful way
<discord-_>
lpg. — MJ presumes the maneuver time is "in the middle" of the maneuver, but flight planner places it at the start
<discord-_>
Sage. — I see, what about using smart a.s.s. to hold attitude while performing the burn manually?
<discord-_>
lpg. — you can tell principia to plot it as an "instantaneous maneuver" which matches MJ's expectations better; but then principia instadeletes the maneuver as soon as that time is past, and MJ don't like that
<discord-_>
lpg. — yes _that_ works fine
<discord-_>
lpg. — personally I use krpc to perform the burn, to get more precise start & stop times than I can do manually. kOS works well too
<discord-_>
Sage. — After spending the whole day fiddling with principia I can't say it improved my experience, in any way :/
<discord-_>
lpg. — it's awful until it clicks
<discord-_>
lpg. — then it's amazing and you (by which I mean I) never want to go back
<discord-_>
egg. — if some of those for whom it has clicked want to write some guides, that might be helpful
<discord-_>
Sage. — this ^
<discord-_>
egg. — I can review them for obvious wrongness, but I am the worst possible person to write an introductory guide
<discord-_>
egg. — what with knowing how the sausage is made
<discord-_>
lpg. — I really don't think the click can be explained
<discord-_>
egg. — like teaching a cat how to use a catflap
<discord-_>
egg. — just keep shoving it through until it clicks
<discord-_>
lpg. — though honestly, it's a misrepresentation to refer to a single click. I still don't know wtf to do with the navball
<discord-_>
Sage. — I haven't even tried to understand the navball, atm I can't even understand the reference frames, I somehow managed to plot a free return trajectory, using earth moon barycenter, happy with myself I perform my burn only to end up making a new crater on the moon
<discord-_>
lpg. — there was a conversation sometime in the past 48 hours, which I think can be summarized as "the ... barycenter frames aren't actually useful"
<discord-_>
egg. — you want to use a moon-centred frame to see where you are with respect to the moon
<discord-_>
egg. — moon-centred earth-aligned most likely
<discord-_>
egg. — in EMB, both the earth and the moon move
<discord-_>
egg. — it is a very useless frame, and I plan to get rid of it because it confuses people
<discord-_>
lpg. — good show on plotting a free-return trajectory in any case. took me ~10 careers to get confident enough to try
<discord-_>
Sage. — I literally followed the tutorial on the wiki to get to the Mun
<discord-_>
egg. — yeah, that is a bit out of date unfortunately
<discord-_>
RurouniDonut. — Lpg, is it easier to execute a burn in krpc compared to kos?
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lpg. — eye of the beholder, I think
<discord-_>
lpg. — I had an easier time of it with kOS, but absolutely _hated_ the "period computer" conceit
<discord-_>
lpg. — with krpc I ran into a weird problem where setting the throttle just didn't work
<discord-_>
lpg. — and hacked around it by, basically, driving the MJ node executor "manually". don't ask, I couldn't explain it
<discord-_>
RurouniDonut. — How did it handle ullage?
<discord-_>
lpg. — not great
<discord-_>
RurouniDonut. — Actually, can a crafts attitude while preparing for a burn impact the final trajectory much?
<discord-_>
lpg. — mostly it hasn't been an issue because the 'swing into the right orientation' maneuver takes care of ullage, but that's not ideal
<discord-_>
lpg. — not in my experience
<discord-_>
lpg. — there's _always_ some finetuning needed after the burn, though
<discord-_>
Sage. — wait I can't use mechjeb to launch to target plane?
<discord-_>
Pteropodidae. — > Actually, can a crafts attitude while preparing for a burn impact the final trajectory much?
<discord-_>
Pteropodidae. — Depends on how unbalanced your RCS is
<discord-_>
lpg. — > wait I can't use mechjeb to launch to target plane?
<discord-_>
lpg. — no that should work ok
<discord-_>
Pteropodidae. — If you have nice and balanced RCS that doesn't have any net translational force, then just rotating shouldn't have a significant effect on your trajectory
<discord-_>
lpg. — (supposing the target plane is reachable. if the target is the moon, that can be tricky)
<discord-_>
Sage. — why is the moon a special targer?
<discord-_>
Sage. — why is the moon a special target? (edited)
<discord-_>
Sage. — and what is an unreachable target plane? Mechjeb used to do dogleg ascents into lower inclination than the launch site like a bauss
<discord-_>
lpg. — it's not, as such. it is, compared to what you may be used to in RSS without principia
<discord-_>
lpg. — because without principia, moon's inclination is fixed. with principia, as in the real world, it wobbles
<discord-_>
lpg. — sure, so long as the dogleg isn't too far away
<discord-_>
lpg. — compensating for a 10-degree misalignment is a dv killer
<discord-_>
egg. — 🐶🍗
<discord-_>
Sage. — so the inclination of the moon wobbles, I launch from Kourou which has a 5 degree inclination, it should be able to launch to whatever inclination the moon is at that time, but it just sits on the launch pad
<discord-_>
lpg. — launching from kourou won't be a problem
<discord-_>
lpg. — launching from KSC cold be
<discord-_>
lpg. — launching from KSC could be (edited)
<discord-_>
lpg. — oh I do remember MJ 'launch into plane' not actually _starting_ the launch
<discord-_>
lpg. — if that's what you're talking about, hitting spacebar when the timer reaches 0 should be all you need
<discord-_>
lpg. — (never bothered digging into why that happened)
<discord-_>
Sage. — I don't think that's my problem, in my launch, mechjeb was stuck on Initializing, funny thing is it staged by itself to start the engines, but wouldn't throttle up
<discord-_>
lpg. — if it's stuck in initializing, it means it's having trouble coming up with a way to hit the target orbit
<discord-_>
lpg. — that probably has nothing to do with 'launch into plane' as such
<discord-_>
lpg. — (or with principia)
<discord-_>
Sage. — well I'll try again tomorrow, I guess even mechjeb needs some rest
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<discord-_>
Butcher. — > Actually, can a crafts attitude while preparing for a burn impact the final trajectory much?
<discord-_>
Butcher. — @RurouniDonut yes, it can.
<discord-_>
Butcher. — I was considering writing a manoeuvre executor for rcs that didn't do alignment, it just thrust in the right direction. For small mid course corrections.
<_whitenotifier-d13c>
[Principia] pleroy assigned issue #2531: Make orbital analysis window available in tracking station - https://git.io/Jff6n
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<_whitenotifier-d13c>
[Principia] pleroy opened pull request #2536: Display the flight planner and the orbit analyser in the tracking station - https://git.io/JfJFt
<_whitenotifier-d13c>
[Principia] pleroy synchronize pull request #2536: Display the flight planner and the orbit analyser in the tracking station - https://git.io/JfJFt
<_whitenotifier-d13c>
[Principia] eggrobin labeled pull request #2536: Display the flight planner and the orbit analyser in the tracking station - https://git.io/JfJFt
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<_whitenotifier-d13c>
[Principia] pleroy synchronize pull request #2536: Display the flight planner and the orbit analyser in the tracking station - https://git.io/JfJFt
<kmath>
YouTube - Kerbal Space Program - Principia |Minimus Lagrange Point L5 | Real Physics in KSP
<_whitenotifier-d13c>
[Principia] pleroy closed issue #2531: Make orbital analysis window available in tracking station - https://git.io/Jff6n
<_whitenotifier-d13c>
[Principia] pleroy closed pull request #2536: Display the flight planner and the orbit analyser in the tracking station - https://git.io/JfJFt
<_whitenotifier-d13c>
[Principia] pleroy pushed 6 commits to master [+0/-0/±17] https://git.io/JfUfm
<_whitenotifier-d13c>
[Principia] pleroy aa1917e - Make the display logic in OrbitAnalyser similar to that in FlightPlanner. This avoids creating a little window stump in the tracking station.
<_whitenotifier-d13c>
[Principia] pleroy ec545bb - Restructure window rendering to factor out access to the active/predicted vessel.
<discord-_>
dkavolis. — I0418 20:35:03.851507 61100 interface.cpp:647] Principia version 2020032409-Frobenius-107-g380dfa10d826f7e06b8fc1fee414698e3a9d0601-dirty built on 2020-04-18T19:41:03Z by Clang-cl version Clang 10.0.0 for Windows x86-64
<discord-_>
dkavolis. — ```
<discord-_>
dkavolis. — Protobuf had a few issues and zfp would not build with vectorcall
<discord-_>
dkavolis. — Also, ninja has issues with unicode characters in file names
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<discord-_>
Falcon. — ahh, gotcha. Because it had worked fine with Principia for awhile actually, only the most recent update put it out of wack
<discord-_>
egg. — yes, the latest update takes over its functionality essentially
<discord-_>
egg. — (but does it correctly)
<discord-_>
egg. — (which took us about a year to get right, so it is understandable that PersistentRotation would be incorrect)
<discord-_>
Falcon. — neato, i remember reading the patch notes, or *some* of them saying that the bug where when switching SOI, it messed up the orientation, so i figured it also did more in regards to how bodies interact with the spacecraft
<discord-_>
egg. — have you considered rereading the patch notes more carefully :-)
<discord-_>
Falcon. — I would lose 40 seconds out of my day, I cant afford that :p
<discord-_>
Falcon. — i have actually become *better* at reading them
<discord-_>
Falcon. — but i am still bad at it
<discord-_>
Falcon. — probably wouldnt do me any good with how fast i forget stuff
<discord-_>
egg. — > After nearly a year of work, Principia now implements the rotational motion of vessels. This makes the physical simulation more correct in the following areas:
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egg. — >
<discord-_>
egg. — > Angular momentum is now preserved and the vessel obeys Euler's equations for the motion of rigid bodies https://en.wikipedia.org/wiki/Euler%27s_equations_(rigid_body_dynamics). This remains true if the geometry or the distribution of mass in a vessel changes over time.
<discord-_>
egg. — > Vessels properly rotate during warp, and rotation is continuous when warping/unwarping.
<discord-_>
egg. — > Rotational motion brings more realism to the game: please take a moment to watch two short videos which illustrate interesting phenomena:
<discord-_>
egg. — >
<discord-_>
egg. — > The figure skater effect https://youtu.be/jy-_AUxAA7c: Transferring fuel from one tank to another causes the angular velocity to change in the same manner that figure skaters control their speed.
<discord-_>
egg. — > Note that the implementation uses closed-form formulæ so its CPU cost is virtually zero even at the highest warp speed, and there is no accumulation of errors or drifts.
<discord-_>
egg. — >
<discord-_>
egg. — > If you have been using PersistentRotation, we recommend that you uninstall it as the two mods would fight each other and PersistentRotation is not physically correct anyway.
<discord-_>
dkavolis. — Got cmake to generate full project files so that I didn't have to build everything in source
<discord-_>
egg. — > After nearly a year of work, Principia now implements the rotational motion of vessels. This makes the physical simulation more correct in the following areas:
<discord-_>
egg. — >
<discord-_>
egg. — > Angular momentum is now preserved and the vessel obeys Euler's equations for the motion of rigid bodies https://en.wikipedia.org/wiki/Euler%27s_equations_(rigid_body_dynamics). This remains true if the geometry or the distribution of mass in a vessel changes over time.
<discord-_>
egg. — > Vessels properly rotate during warp, and rotation is continuous when warping/unwarping.
<discord-_>
egg. — > Rotational motion brings more realism to the game: please take a moment to watch two short videos which illustrate interesting phenomena:
<discord-_>
egg. — >
<discord-_>
egg. — > The figure skater effect https://youtu.be/QWiRvKfe3SE: Transferring fuel from one tank to another causes the angular velocity to change in the same manner that figure skaters control their speed.
<discord-_>
egg. — > Note that the implementation uses closed-form formulæ so its CPU cost is virtually zero even at the highest warp speed, and there is no accumulation of errors or drifts.
<discord-_>
egg. — >
<discord-_>
egg. — > If you have been using PersistentRotation, we recommend that you uninstall it as the two mods would fight each other and PersistentRotation is not physically correct anyway. (edited)
<discord-_>
Falcon. — also, really good work egg
<discord-_>
dkavolis. — In addition, it can also handle all your separate scripts
<discord-_>
Falcon. — it is insane how much you guys devote to this mod ❤️
<discord-_>
egg. — @dkavolis yeah that is really not a direction we want to go in re. the build system
<discord-_>
egg. — we rather like the hand-rolled props
<discord-_>
lpg. — on the rotation topic...PR had a useful gameplay feature: if SAS was on and rotation "slow enough" when activating time warp, rotation would go to zero. Essentially compensating for the fact that one can't rcs under warp. I'm guessing Principia doesn't do anything of the kind?
<discord-_>
egg. — nope
<discord-_>
Falcon. — that was what was causing me issues i guess
<discord-_>
egg. — we could try thinking of something, but then you have the question of specifying the orientation you want and its reference frame, etc.
<discord-_>
Falcon. — when i would go to time warp, my craft would start moving all over the place even though it was basically stopped
<discord-_>
dkavolis. — You can still control all the options and it works cross-platform
<discord-_>
Falcon. — so i had to spin stabilize everything
<discord-_>
Falcon. — and for stuff that couldnt spin stabilize, oh well
<discord-_>
egg. — @dkavolis more importantly, we are not really interested in adding more setups
<discord-_>
Falcon. — but i will try it out with just principia now to see how it is
<discord-_>
egg. — as long as we have a setup where we can build on the three platforms and it works, maintaining build environments is not interesting
<discord-_>
egg. — nor is understanding the shiny new tool for build environment
<discord-_>
egg. — nor is understanding the shiny new tool for build environments (edited)
<discord-_>
egg. — (and it goes without saying that a thing that has issues with Unicode filenames is not fit for purpose here :-p)
<discord-_>
badgermasher. — Question for more veteran users of Principia with RSS. I'm planning a polar launch from the Cape for a lunar impactor. I think I have a plan worked out but I'm curious what dV range you all plan for with your polar TLI.
<discord-_>
badgermasher. — Not sure if I'm being exceedingly wasteful or not, seems about the best I can do is ~3380 m/s. I've not done polar launches before and I'm new to principia, so it's a bit of a head scratcher for me.
<discord-_>
Falcon. — it is about the same as regular TLI, you just need an extra 500-700 m/s to get into that polar orbit
<discord-_>
Falcon. — and about 3400 m/s for TLI seems right
<discord-_>
badgermasher. — Not sure if I'm being exceedingly wasteful or not, seems about the best I can do is ~3380 m/s. I've not done polar launches to TLI before and I'm new to principia, so it's a bit of a head scratcher for me. (edited)
<discord-_>
Falcon. — that is what i about did for my first launches to the moon because i didnt know how to launch into the plane of the moon with PVG at first
<discord-_>
Falcon. — are you completely off the table for doing a 28 degree TLI?
<discord-_>
lpg. — I'm currently looking at previous career's first impactor, and for some reason I only gave it 3137. that feels short, so now I have to wonder what I've forgotten
<discord-_>
neph. — 🥚 🍞
<discord-_>
Falcon. — that is about the bare minimum lpg
<discord-_>
Falcon. — you can do it with that
<discord-_>
Falcon. — lowest i got was about 3135
<discord-_>
egg. — @neph well, sometimes I also make brioche, yes
<discord-_>
lpg. — but planning for the bare minimum wouldn't have been wise
<discord-_>
egg. — 🥚🧈🍞
<discord-_>
neph. — Does🥚🥐 ?
<discord-_>
Falcon. — what is the appeal to a polar TLI btw?
<discord-_>
egg. — I have been meaning to try making some, but time
<discord-_>
lpg. — trivial to time the launch. I still only have a very rough process for timing due-east launches
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<discord-_>
lpg. — had, rather. I bet I'll have forgotten it and have to reinvent it next time I need it
<discord-_>
Falcon. — are you opposed to using PVG to help with lunar launches?
<discord-_>
lpg. — no help at all. matching planes isn't an option
<discord-_>
Butcher. — @badgermasher I normally plan for 12.5k for direct ascent so that's about 3.3 for tli I guess?
<discord-_>
Butcher. — @Falcon my appeal for polar is that you don't need to plane match, which can be expensive if the moon is not at a convenient inclination.
<discord-_>
Falcon. — i almost always get a plane match from brownsville at 26 degrees from the equator
<discord-_>
lpg. — with principia, that's something that happens for a couple of years every 18
<discord-_>
lpg. — (is it 18?)
<discord-_>
Butcher. — Yeah around that. Last time I was doing lunar flights the moon was inclined 18° to the equator.
<discord-_>
egg. — yeah nodal precession is 18.6 years
<discord-_>
Butcher. — And I was launching from the Cape.
<discord-_>
Butcher. — This play I'm at Vandenburg so it'll be worse.
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<discord-_>
Falcon. — i dont know how PVG does it then
<discord-_>
Falcon. — because it gets me onto a really nice orbit with the moon every time
<discord-_>
Falcon. — and i dont mean just burning from the equator and ending up on some inclined orbit injection to the moon, it gets me on an orbit that allows me to inject straight to the equatorial plane of the moon with no extra deltaV needed for inclination change along the way
<discord-_>
lpg. — are you sure you're using principia?
<discord-_>
lpg. — "straight into the equatorial plane of the moon" doesn't sound right _at all_
<discord-_>
Falcon. — i will take a picture if you want when i do it again
<discord-_>
Falcon. — and yes i am sure i am playing principia
<discord-_>
egg. — @lpg I think I had some luck launching to a parking orbit in the plane of the moon with Principia using PVG a while back, but I do not recall the specifics and I do not have easy access to a machine that can run RSS/RO at a decent speed at this time
<discord-_>
lpg. — it's certainly possible when the calendar cooperats and the dv is sufficient
<discord-_>
egg. — yeah, don’t launch from the US, it’s a silly place :-p
<discord-_>
Falcon. — idk, i just know that my Rockets take off from Brownsville at about 28 degrees north
<discord-_>
Falcon. — at a specific time of day
<discord-_>
egg. — what is the year
<discord-_>
Falcon. — 1969
<discord-_>
egg. — 28°36′ is as far as it gets; since you are very close to that you will very quickly lose launch-overhead capability
<discord-_>
lpg. — that would be the ideal period
<discord-_>
egg. — so, enjoy it while it lasts :-p
<discord-_>
Falcon. — it is july of 69
<discord-_>
Falcon. — if that narrows it down any more
<discord-_>
Falcon. — so basically... right around apollo 11
<discord-_>
egg. — it will be gone before the decade is out :D
<discord-_>
Falcon. — ive been using PVG for lunar planes for... 2 years now?
<discord-_>
Falcon. — its been fine for the most part
<discord-_>
egg. — (not sure what the exact timespan is at your latitude, but you are on the more extreme end of things definitely)
<discord-_>
lpg. — > with principia, that's something that happens for a couple of years every 18
<discord-_>
Falcon. — so im at the very end? noooooo