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…
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<queqiao-> ⟨TheSquirrelPatrol⟩ So someone said something to the effect of "Use ECEF and burn retrograde" which would appear to be the same as the combined ECI prograde/normal burn. Can someone explain that to me in small words? And how would you know? For example for the Venus transfer I'm doing, I know how to set it up with the plotting frame set to a venus frame and the manuever set to ECI, but no clue if the manuever is set to the venus mode..
<queqiao-> ⟨Quadrupole⟩ For the first part, you know in ECEF a GEO satellite would be stationary, so all you need to do is to cancel out its velocity at the correct altitude in this frame.
<queqiao-> ⟨Quadrupole⟩ Which is to burn retrograde in ECEF.
<queqiao-> ⟨Quadrupole⟩ I don't quite understand the second part though. Are you trying to find a way to plan your TVI maneuver in a Venus-related frame?
<queqiao-> ⟨TheSquirrelPatrol⟩ I'm trying to plan a TVI, yes. I started with ECI to make sure I was burning at the more or less right time, then swapped to HCI to see my solar orbit, then finally swapped to VSO to fine tune. But the whole time I kept the manuever frame set to ECI
<queqiao-> ⟨TheSquirrelPatrol⟩ Is that a good method, or should I have done something different?
<queqiao-> ⟨egg⟩ the manœuvre frame for the ejection burn should be ECI, you are correct
<queqiao-> ⟨egg⟩ The manœuvre frame for the capture burn should probably be VCI. Note that each manœuvre has its own manœuvre frame.
<queqiao-> ⟨TheSquirrelPatrol⟩ I got my flyby encounter, but it cost me nearly 800m/sec more than transfer window planner told me it should
<queqiao-> ⟨TheSquirrelPatrol⟩ But I assume that's just me not picking the trajectory TWP had in mind
<queqiao-> ⟨Quadrupole⟩ We can't really tell without looking at a few screenshota
<queqiao-> ⟨Quadrupole⟩ * screenshots
<queqiao-> ⟨Kirk (He/Him)⟩ If this is the correct version of TWP, that sounds like incorrect LAN
<queqiao-> ⟨TheSquirrelPatrol⟩ I ended up spending a lot more, and getting a transfer that took nearly twice as long, so clearly I did not do what TWP expected me to
<queqiao-> ⟨TheSquirrelPatrol⟩ or wait no, I did it in less time, not more
<queqiao-> ⟨TheSquirrelPatrol⟩ but I assume I didn't eject at the correct time/angle
<queqiao-> ⟨TheSquirrelPatrol⟩ I used the "moonlaunchwindow" kos script, but swapped Venus as the target body in the script, and then did about 3 orbits to let my engine cool, and then plotted my node
<queqiao-> ⟨Kirk (He/Him)⟩ That is not how you use any of those things?
<queqiao-> ⟨Kirk (He/Him)⟩ TWP gives you a LAN
<queqiao-> ⟨Kirk (He/Him)⟩ Just launch to the inclination and LAN it tells you
<queqiao-> ⟨TheSquirrelPatrol⟩ So for this Mars mission coming up:
<queqiao-> ⟨TheSquirrelPatrol⟩ Launch to 31.98 degrees inclination to LAN 341.53?
<queqiao-> ⟨TheSquirrelPatrol⟩ Do I want to try and time my TMI to that UT, or is that launch time?
<queqiao-> ⟨Quadrupole⟩ Exact time does not matter. Within a day or two you are good to go
<queqiao-> ⟨Quadrupole⟩ It's your ejection phase that matters, that you get from tuning maneuver time
<queqiao-> ⟨Quadrupole⟩ * angle that matters, which you get from tuning maneuver start
<queqiao-> ⟨TheSquirrelPatrol⟩ Is that value shown somewhere in principia or mechjeb?
<queqiao-> ⟨TheSquirrelPatrol⟩ I assume it must be
<queqiao-> ⟨Quadrupole⟩ you don't need the numerical value of ejection phase angle. You just optimize your ejection time once you are at the parking orbit
<queqiao-> ⟨Quadrupole⟩ Or, there should be a graphical display on TWP about where your ejection should be
<queqiao-> ⟨Quadrupole⟩ There should also be a graphical display of your parking orbit too
<queqiao-> ⟨TheSquirrelPatrol⟩ I don't see anything like that
<queqiao-> ⟨Quadrupole⟩ It's in map view
<queqiao-> ⟨TheSquirrelPatrol⟩ Ok I see that there are more buttons if I do this in the tracking center
<queqiao-> ⟨TheSquirrelPatrol⟩ That's cool, I had no idea that was there, thanks.
<queqiao-> ⟨Starscraper⟩ I also just noticed today that you can put up the burn markers with TWP while planning your approach - this is useful for if you capture into a highly elliptical orbit and want to put your Venusian periapsis as close to the "burn" marker as possible to make the return trip more efficient.
<queqiao-> (Note this screencap has a fatal mistake in it - the TWP burn/ejection angle markers are in inertial frames, and I'm plotting this in VSO - I need to plot it in VCI)
<queqiao-> Though for this particular launch/flight time, I wasn't able to line up the Pe with the burn marker. Maybe later I'll experiment some more with
<queqiao-> 1. shorter and longer flights to Venus, maybe changing the angle I approach from, and
<queqiao-> ⟨Starscraper⟩ I also just noticed today that you can put up the burn markers with TWP while planning your approach - this is useful for if you capture into a highly elliptical orbit and want to put your Venusian periapsis as close to the "burn" marker as possible to make the return trip more efficient.
<queqiao-> (Note this screencap has a fatal mistake in it - the TWP burn/ejection angle markers are in inertial frames, and I'm plotting this in VSO - I need to plot it in VCI)
<queqiao-> ⟨Starscraper⟩ Though for this particular launch/flight time, I wasn't able to line up the Pe with the burn marker. Maybe later I'll experiment some more with
<queqiao-> 1. shorter and longer flights to Venus, maybe changing the angle I approach from, and
<queqiao-> 2. playing with departure dates some more. The Manned Venus Orbiter study looked at departing Venus just 20-40 days after arriving. In my planning, here, I was looking at staying in Venusian orbit for over a year and returning on the next window. But that might be a fatal flaw.
<queqiao-> ⟨Starscraper⟩ Oh, whoops, sorry, wrong link on the webarchive. This is what I meant to link: https://web.archive.org/web/20100530041122/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670017910_1967017910.pdf
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<queqiao-> ⟨egg⟩ So, apparently GitHub now has a discussions thing, which I am told is a sort of stackoverflow-like thing you can put on your repo. I wonder if that could be used to deal with the common questions that get asked here or on the forums…
<queqiao-> ⟨egg⟩ (pinned messages are not the most effective thing, and the FAQ is a bit of an unmaintained mess tbh)
<queqiao-> ⟨egg⟩ (this thing https://docs.github.com/en/discussions)
<queqiao-> ⟨面条参考系⟩ Well you’re still assuming that a) people will find it and b) people will read it even if they find it
<queqiao-> ⟨egg⟩ True. People find their way here, not so much to the FAQ, so keeping things in one place may be useful even if the medium is suboptimal.
<queqiao-> ⟨egg⟩ (keeping an eye on QQ is already tricky, more things to forget is probably a bad idea…)
<queqiao-> ⟨egg⟩ (speaking of which, I should log into QQ…)
<queqiao-> ⟨Galactic Toast⟩ can mechjeb perform principia flight plans like it can perform maneuver nodes?
<queqiao-> ⟨Stonesmile⟩ Yes, there is a "perform Principia burn" button
<queqiao-> ⟨Galactic Toast⟩ thanks
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<NinjaPanda> Hi all, I'm having an issue where I cannot target anything from the map view. In the Principia menu under KSP Features there is only the option to display patched conics, and the target celestial option is missing. Anyone have any insight?
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<queqiao-> ⟨Stonesmile⟩ You might have to upgrade the tracking station, if you are in career
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