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->
⟨7x7 Mirror Cube (Level 15)⟩ ⟪Denwey⟫ wdym? 🤔 it's the truth and the Lord's […] ⮪ is mars flat too?
<queqiao->
⟨Denwey⟩ ⟪7x7 Mirror Cube (Level 15)⟫ is mars flat too? ⮪ uhh, eh, hmm...
<raptop>
1) The Lord's land is flat
<raptop>
2) Earth, Mars, and every other planet, asteroid, star, and the like we see are not
<raptop>
3) This is not a good place
<queqiao->
⟨Le Fishe⟩ ⟪7x7 Mirror Cube (Level 15)⟫ is mars flat too? ⮪ Unlike earth, it has been proven mars is round
<queqiao->
⟨7x7 Mirror Cube (Level 15)⟩ principia is confusing
<queqiao->
⟨Le Fishe⟩ That looks perfectly understandable to me
<queqiao->
⟨Al₂Me₆⟩ ⟪7x7 Mirror Cube (Level 15)⟫ principia is confusing ⮪ ...is that not from the Trajectories mod?
<queqiao->
⟨7x7 Mirror Cube (Level 15)⟩ ⟪Al₂Me₆⟫ ...is that not from the Trajectories […] ⮪ i didn't know it had that
<queqiao->
⟨egg⟩ don’t use Principia with Trajectories, you will be confused and misled by trajectories shown in the wrong frame and which do not accurately reflect the motion
<queqiao->
⟨egg⟩ Use Principia’s plotting frame selector if you want to look at your trajectory in a different reference frame instead.
<queqiao->
⟨Al₂Me₆⟩ I suppose it has some limited value for predicting the effect of atmospheric drag, but yeah even that needs to be used carefully...
<queqiao->
⟨Butcher⟩ I use it a little but it's trajectories off until you have an orbit that might intersect the atmosphere.
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⟨strelka ✩⟩ does principa show aerobraking in its predictions ?
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⟨Stonesmile⟩ No, hence the previous discussion about that being one of the few uses for the Trajectories mod with Principia
<queqiao->
⟨strelka ✩⟩ oh, I'm dumb I didn't even read up
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⟨Cirelion⟩ So it's not recommended at all, but for aerobraking it's essentially needed to get a accurate prediction? But it's also not accurate at all? I'm slightly confused, if it's inaccurate how is it only usefull for aerobraking? That is magically more accurate?
<queqiao->
Or is it that because it accounts for it at all while principia doesn't that it'll be more accurate than principia itself?
<queqiao->
⟨test_account⟩ aerobraking is not accurate
<queqiao->
⟨test_account⟩ accurate aerobraking is 🧀
<queqiao->
⟨strelka ✩⟩ there's no way some space agency out there doesn't have a good way of calculating semi-accurate aerobraking for flight plans ?? how is that cheese
<queqiao->
⟨strelka ✩⟩ it's not that asccurate anyways with trajectories since reentry profiles, lifting reentries, etc can change the aerobraking trajectory entirely
<queqiao->
⟨test_account⟩ on earth maybe, but afaik it has been done just once with the zond probes
<queqiao->
⟨test_account⟩ on other planets no
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⟨Cirelion⟩ So it's just never accurate then?
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⟨test_account⟩ it shouldn't be, the atmosphere varies
<queqiao->
⟨test_account⟩ the game doesn't model that so you can sim it until it's accurate
<queqiao->
⟨Cirelion⟩ Right, then why would Trajectories ever have a use? It seems like there's quite literally no point to using it right?
<queqiao->
⟨test_account⟩ for atmospheric landing I suppose
<queqiao->
⟨test_account⟩ if you need a more or less precise location
<queqiao->
⟨Vlood⟩ ⟪strelka ✩⟫ there's no way some space agency out […] ⮪ yup, just run a CFD simulation inside KSP, no big deal
<queqiao->
⟨strelka ✩⟩ ⟪Vlood⟫ yup, just run a CFD simulation inside […] ⮪ it's not like I can pre-plan it on the ground outside of simulating it a dozen times so I know the altitude/speed to get what I want
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⟨strelka ✩⟩ it feels just as cheese to quicksave a dozen or so times until you get it right
<queqiao->
⟨Vlood⟩ ⟪strelka ✩⟫ it feels just as cheese to quicksave a […] ⮪ That's what simming is for
<queqiao->
⟨strelka ✩⟩ that logic doesn't add up 🤷
<queqiao->
⟨Vlood⟩ You wanted a non-cheesy way of doing something over and over again, sims are just that
<queqiao->
⟨strelka ✩⟩ so what if you use the trajectory plugin _in_ sim and then using that info, use that for your flight plan
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⟨DRVeyl⟩ Mostly this conversation doesn't make sense.
<queqiao->
Precise aero breaking doesn't happen because the atmosphere is neither uniform with altitude nor consistent across time. Solar activity, for one, causes variation.
<queqiao->
Aero breaking IRL is more about gradually lowering energy/Ap across many passes. The individual variation doesn't matter because the precision of the result doesn't matter, and you can always measure the result and repeat or exit the loop.
<queqiao->
KSP doesn't model any of that. So you get perfectly predictable results. And this a mod like trajectories exists, and even has FAR integration.
<queqiao->
What it doesn't have is an idea of Principia. So when it tries to draw a path that doesn't hit the planet, it's going to be something wrong because it has no idea that Principia is also drawing things, modifying the trajectory outside of atmosphere, and further that it is drawing things in a frame of reference other than the stock one.
<queqiao->
⟨DRVeyl⟩ * thus
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⟨Cirelion⟩ Thanks for that explanation, helped clear out alot of the confusion for me. So essentially as long as you're within atmosphere it would work fine because principia doesn't really affect the trajectories there. But otherwise they don't know about each other and will therefore show incorrect results.
<queqiao->
⟨test_account⟩ it will only work fine if you set principia to the same reference frame that trajectories is using
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⟨test_account⟩ otherwise you will see a confilcting mess also when in the atmosphere
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⟨test_account⟩ * conflicting
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⟨Marsh⟩ I found it to be more trouble than it’s worth. It’s nice having guidance to follow for a runway shuttle landing, but like DRVeyl said, having this level of prediction and consistency isn’t very realistic
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⟨Cirelion⟩ It's more exciting to eyeball it anyway 😛
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<queqiao->
⟨DRVeyl⟩ Also that while within the atmosphere, the non uniform effects of gravity just don't play as significant of a role over such a short duration, usually.
<queqiao->
⟨DRVeyl⟩ +/ non 2-body
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⟨DRVeyl⟩ * n-body
<queqiao->
⟨DRVeyl⟩ They perturb, but generally much less than drag does.