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…
<queqiao-_>
⟨TurboEJ20⟩ So hey all, coming from using mechjeb for like the last 6 years for everything....how do i do precise burns in principia. If i have Mechjeb do the burn the bar does not go down. What are we supposed to be doing to be accurate?
<queqiao-_>
⟨Paculino (ŝi/ri/she/they)⟩ you can manually start and end it and take the spool up time of about one or two seconds into account
<queqiao-_>
⟨Paculino (ŝi/ri/she/they)⟩ Better Time Warp slow motion helps with precision very well
<queqiao-_>
⟨Paculino (ŝi/ri/she/they)⟩ And you can always fine tune with rcs later if you are just barely off
<queqiao-_>
⟨SpaceFace545⟩ Mechjeb can execute principia nodes
<queqiao-_>
⟨SpaceFace545⟩ The bar won’t go down because principia overrides the stock node editor
<queqiao-_>
⟨SpaceFace545⟩ Principia runs off a burn time system instead of delta v expenditure
<queqiao-_>
⟨TurboEJ20⟩ So does MJ still burn for the Dv target or does it just go forever
<queqiao-_>
⟨TurboEJ20⟩ im just trying to stay launching from Florida and get my first moon impact and stuff, but with single burn engines its proving very difficult. I can do the math and execute it manually which i did on my first fly by. But after that i would rather the computer system made for it execute it for me.
<queqiao-_>
⟨egg⟩ There is Principia support in MechJeb (though it doesn’t account for spool-up). If your thing is burning forever, you are misusing MechJeb.
<queqiao-_>
⟨TurboEJ20⟩ roger, so it should get close and i can just RCS adjust from there
<queqiao-_>
⟨TurboEJ20⟩ let me be more clear
<queqiao-_>
⟨egg⟩ (there should be a button that says « execute Principia manœuvre » or something along those lines)
<queqiao-_>
⟨TurboEJ20⟩ yea
<queqiao-_>
⟨TurboEJ20⟩ so once i hit that
<queqiao-_>
⟨TurboEJ20⟩ even tho the bar does not go down, Mechjeb will still burn for the indicated Dv target correct?
<queqiao-_>
⟨egg⟩ MechJeb will ignite when Principia says the ignition should happen, and cut off when it says it should cut off.
<queqiao-_>
⟨egg⟩ There is no measuring of the actual Δv going on.
<queqiao-_>
⟨TurboEJ20⟩ based on time right?
<queqiao-_>
⟨TurboEJ20⟩ rgr
<queqiao-_>
⟨egg⟩ in particular, spool-up time will result in burning under target.
<queqiao-_>
⟨egg⟩ any sub-nominal thrust due to :agathorn: will likewise result in burning under target. MechJeb will not care about that, and cut off on time.
<queqiao-_>
⟨TurboEJ20⟩ gotcha, thanks
<queqiao-_>
⟨Falcon⟩ Question, how accurate is Principia compared to the software NASA uses for their mission planning, if Egg has been able to compare or see i suppose
<queqiao-_>
⟨Quadrupole⟩ 1) The interplanetary trajectories are both *ab initio*, so Principia and NASA's program (e.g., GMAT) should be equally accurate.
<queqiao-_>
⟨Quadrupole⟩ 2) Principia has fewer terms in geopotential models (e.g., 30th-order for the moon), whereas GMAT has up to 165th-order. So if you are planning a lunar orbiter that will orbit the moon for ten years, there might be some deviation from reality for Principia.
<queqiao-_>
⟨Quadrupole⟩ Of course, the integrator and integration length of Principia and NASA's program could be different, but that depends on how much computational resources you are willing to invest.
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<queqiao-_>
⟨D0m1nu2⟩ Hey, does anyone also have problem with sunflare after installing latest version of Principia?
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<queqiao-_>
⟨sichelgaita⟩ Things that Principia doesn't do that NASA probably cares about:
<queqiao-_>
⟨sichelgaita⟩ For celestials: axial precession, general relativity, electrodynamic effects.
<queqiao-_>
⟨sichelgaita⟩ For vessels: orbital decay, radiation pressure.
<_whitenotifier>
[Principia] pleroy opened pull request #3170: Convert mathematica, physics, astronomy and testing_utilities to DiscreteTraject0ry - https://git.io/JiGoA
<queqiao-_>
⟨Soviet Onion⟩ Google Translate time !
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<_whitenotifier>
[Principia] pleroy closed pull request #3170: Convert mathematica, physics, astronomy and testing_utilities to DiscreteTraject0ry - https://git.io/JiGoA
<_whitenotifier>
[Principia] pleroy pushed 8 commits to Ondelette [+0/-0/±62] https://git.io/JiZXr
<_whitenotifier>
[Principia] pleroy 9133942 - DiscreteTraject0ry in mathematica.
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[Principia] pleroy 8f87728 - DiscreteTraject0ry in physics.
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[Principia] pleroy 72e52ca - A few code cleanups.
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[Principia] ... and 5 more commits.
<queqiao->
⟨sichelgaita⟩ For the poor souls who don't understand French, here is my translation of the bottom strip:
<queqiao->
⟨sichelgaita⟩ Here is Earth, which, as we know, is a flat disk having Bagdad as its centre.
<queqiao->
⟨sichelgaita⟩ Here is the canopy of heaven, which rotates on itself, and on which the celestials are pinned. The canopy is made of velvet, of course.
<queqiao->
⟨sichelgaita⟩ With an appropriate fuel I have found a way to send the machine to the most distant celestials.
<queqiao->
⟨sichelgaita⟩ For the poor souls who don't understand French, here is my translation of the bottom strip:
<queqiao->
⟨sichelgaita⟩ Here is Earth, which, as we know, is a flat disk having Baghdad as its centre.
<queqiao->
⟨sichelgaita⟩ Here is the canopy of heaven, which rotates on itself, and on which the celestials are pinned. The canopy is made of velvet, of course.
<queqiao->
⟨sichelgaita⟩ With an appropriate fuel I have found a way to send the machine to the most distant celestials. (edited)
<queqiao->
⟨egg⟩ or perhaps pinned to the vault of heaven which is made of velvet (edited)
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