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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Reply to "ezsnack: You cant read it is what it is"
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<Kaga> I did as followed and wanted it to get closer after the 1 minute coast to correction burn
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<Kaga> Not sure what i misread cuz i followed as told..?
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<egg> two days seems to be rather larger than one minute
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Reply to "ezsnack: step by step. right after TVI cuts off, reset the flight plan to blank and rebase set man..."
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<Kaga> This one
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<ezsnack> step by step.
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<ezsnack> right after TVI cuts off, reset the flight plan to blank and rebase
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<ezsnack> set maneuvering frame to ECI and reference frame to VCI/VSO
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<ezsnack> set the timing of the node to 1 minute away or w/e it takes your craft to rotate to aim it.
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<ezsnack> only change prograde and retrograde to get the lowest PE at venus that you can.
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<ezsnack> let the optimizer do the rest.
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<ezsnack> (if the optimizer adds too much radial component at this point it means that your burn was too late or early)
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Reply to "egg: two days seems to be rather larger than one minute"
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<Kaga> I already did 1 minute burn
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<Kaga> This is after
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Reply to "Kaga: I did as followed and wanted it to get closer after the 1 minute coast to correction burn"
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<Kaga> Read?
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<Kaga> TVI burn -> 1 minute coast and adjust. -> optimizerGot 300dv at cheapest hour
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<egg> The idea is that after the correction burn which is one minute after your TVI, you are the trajectory you want. Why do you have a second correction two days afterwards?
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Reply to "egg: The idea is that after the correction burn which is one minute after your TVI, you are on..."
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<Kaga> To get closest encounter, 200km above venus
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<egg> Why did you not achieve that with your earlier correction?
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<Kaga> At its cheapest
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Reply to "egg: Why did you not achieve that with your earlier correction?"
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<Kaga> Because it went to 500
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<egg> Where did the planned TVI (before you executed it) actually get you?
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Reply to "egg: Where did the planned TVI (before you executed it) actually get you?"
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<Kaga> 2,000,000,km
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<Kaga> With adjustments without getting absurdly expensive
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<egg> Then your plan was bad, and you are paying for that?
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Reply to "egg: Then your plan was bad, and you are paying for that?"
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<Kaga> I plotted at the time to burn what TWP shows in orbit and adjusted as I pleased, how did i plan bad?
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<Nazfib> The manœuvre TWP(2) gives you, is just an approximation (especially with Principia). You need to adjust it to actually get close to Venus.
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<ezsnack> wrong manoeuvreing frame also :||||||||
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Reply to "Nazfib: The manœuvre TWP(2) gives you, is just an approximation (especially with Principia). You ..."
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<Kaga> So its normal to get 300dv adjustment for closest approach?
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<egg> And the adjustments you made are nowhere near good enough if they get you to 2 000 000 km when you want 200.
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Reply to "ezsnack: wrong manoeuvreing frame also :|||"
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<Kaga> I already told u, i did ECI for ejection, and VSO for correction
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Reply to "Kaga: So its normal to get 300dv adjustment for closest approach?"
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<egg> NO, your plan is bad. You must not do what TWP tells you without fixing it first.
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<egg> If you do what TWP tells you and what TWP tells you gets you to the wrong place, then you will have to break the bank to undo the bad plan.
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Reply to "Kaga: I already told u, i did ECI for ejection, and VSO for correction"
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<ezsnack> i dont understand whats hard in following a step by step guide lolz
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Reply to "Kaga: So its normal to get 300dv adjustment for closest approach?"
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<Nazfib> To get from a 2 000 000 km, to a 200 km trajectory, I'm not surprised that it takes that much Δv. Adjust your TVI burn (from what TWP gives you) to get 200 km before doing your escape burn.
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Reply to "ezsnack: i dont understand whats hard in following a step by step guide lolz"
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<Kaga> I did follow it, tf was i doing the past few days?
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<egg> You must not start your engines for TVI until the plan for TVI gets you to 200 km.
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<egg> and yes, the manœuvre frame should be ECI for both burns, but that is secondary to the fact that if you make a bad burn, there is no recovering from that cheaply.
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Reply to "egg: You must not start your engines for TVI until the plan for TVI gets you to 200 km."
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<Kaga> When i did my plotting in ECI, getting to venus 200km took 5000,dv on the spot it says
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<Kaga> I tried my best to plot cheaply man, i am not stupid
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<Kaga> Or a moron
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<Nazfib> Could you share a screenshot with the TVI burn planned, and with TWP(2) open, and with some way to show your current (i.e. before TVI) orbit's inclination and LAN?
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<Kaga> I will when i get home, every second of proof.
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<ezsnack> cant you just go watch a video of carnasa doing it or something lol
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Reply to "ezsnack: cant you just go watch a video of carnasa doing it or something lol"
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<Kaga> I am not familiar who that is :v
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<Nazfib> If your TVI burn takes 5000 m/s instead of TWP(2)'s prediction of ~3900 m/s, then something is really wrong.
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<egg> ezsnack, yes, but let’s please not focus on your instructions for planning a correction when the main issue is that the TVI itself is incorrigible to start with, this discussion is confused enough as it is.
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<ezsnack> this is just a misplaced correction, after the correction he would be on the right arrival timing, only 2 days off
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Reply to "Kaga: The vso is there to see venus PE. I use ECI for adjustment."
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<ezsnack> manoeuvreing frame and reference frame ARE NOT the same thing
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Reply to "ezsnack: you cant fix 1000dv off course with less than 1000dv (and a lot more if you are burning i..."
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<egg> Can we please try to figure out why the initial plan starts being 1 km/s off, instead of why Kaga cannot follow your instructions for doing something that is doomed to fail because the plan is broken to start with?
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Reply to "Nazfib: Could you share a screenshot with the TVI burn planned, and with TWP(2) open, and with so..."
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<egg> This would be what we need to figure out what on earth is going on.
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<ezsnack> the inital plan is correct, he has a 5k transfer for some reason, dont ask why but the time of travel matches 😐
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<egg> I am asking why. That is the only interesting question.
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Reply to "ezsnack: the inital plan is correct, he has a 5k transfer for some reason, dont ask why but the ti..."
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<Kaga> IF i adjusted it during TVI
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<Vlood> Obvious sanity check: does the parking orbit as flown correspond with the one given by TWP for that specific transfer?
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Reply to "Vlood: Obvious sanity check: does the parking orbit as flown correspond with the one given by TW..."
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<Kaga> Yes
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<egg> (Also, while I am being grumpy on the internet, can you all please stop using dv as a unit? Δv is a quantity which is a speed. The unit is m/s or km/s.)
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Reply to "Kaga: IF i adjusted it during TVI for 200km"
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<ezsnack> Mmm you are plotting tvi eith vso manouvering frame i guess too ahahahah
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<ezsnack> So wasting radial component to wrong timing
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<ezsnack> but you dont think its radial because you are only adjusting prograde, which doesnt mean anything as you are orbiting earth
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Reply to "ezsnack: Mmm you are plotting tvi eith vso manouvering frame i guess too ahahahah"
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<egg> While we are on terminology, plotting is the term we use for the plotting frame , the reference frame you use to look at things. You mean planning.
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Reply to "ezsnack: manoeuvreing frame and reference frame ARE NOT the same thing"
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<egg> And here you mean plotting frame , not reference frame.
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<ezsnack> ill try to be more accurate :v
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Reply to "egg: And here you mean plotting frame , not reference frame."
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<ezsnack> i actually didnt know the correct name for this
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<egg> (If I were snarky I might point out that you need only read it from the UI, where it says « Plotting frame selection ».)
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<ezsnack> i dont think i ever read the ui accurately XD
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Reply to "ezsnack: but you dont think its radial because you are only adjusting prograde, which doesnt mean ..."
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<kuzinat0r> I often find interplanetary burns not accurate enough. Usually mechjeb overshoots, so it's better to cut off manually
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Reply to "kuzinat0r: I often find interplanetary burns not accurate enough. Usually mechjeb overshoots, so it'..."
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<Nazfib> That's interesting. I'm just now doing a test launch (Atlas-Agena, 230 kg to Venus), and MJ overshot the manœuvre by less than 0.5 m/s. It cannot get much more accurate than that — and it didn't even have prograde RCS, this was all done by timing the engine shutdown.
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<ezsnack> I find that with rd0105 you need to delay the node by 2s to get it within 5ms
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<ezsnack> And reduce prograde by 1ms
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Reply to "ezsnack: none of these 4 things are correct in this screenshot, how can you say you are doing ever..."
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<egg> That is not the actual parking orbit, that is where TWP tells you to go. What do the orbit analyser and the osculating elements from MJ say after launch?
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Reply to "egg: That is not the actual parking orbit, that is where TWP tells you to go. What do the orbi..."
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<Kaga> like right now in transit or do i reset the launch again
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<egg> The question (which is Nazfib’s question from above) is about your parking orbit, the orbit you are in before you execute the TVI burn.
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<egg> Frankly, you can skip the whole part where you do the TVI burn, until we figure out why you can’t get it anywhere close to Venus without spending an additional 1.5 km/s, the rest is irrelevant.
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<Kaga> let me reset launch and check parking orbit LAN
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<egg> And also show us what TWP says about the 10th of November
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<Kaga> im doing that right now on the actual day, 10th november, gimme a bit
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<Kaga> i may have done the date wrong earlier, this should be more accurate now
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<Kaga> what causes this slight inaccuracy at launch?
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<ezsnack> what is goign on int he final to last screenshot? blind adjustment?
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<ezsnack> why do you switch the plotting frame back to eci lol
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Reply to "Kaga: TWP vs Orbit"
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<ezsnack> that the pvg prediction doesnt account for atmospheric losses, also the orbital elements given by mj are irrelevant with principia, your orbital elements are in the orbit analysis and map view
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Reply to "ezsnack: what is goign on int he 2nd to last screenshot? blind adjustment?"
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<Kaga> Not blind adjust, checked VSO and plotted the DV in ECI mode to see how close i got with adj. after that, all are pressed back to ECI frames
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<ezsnack> also you are 5 days off, just use twp to check the window again, dont focus on a single day since it will have shifted with principia
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Reply to "Kaga: Not blind adjust, checked VSO and plotted the DV in ECI mode to see how close i got with ..."
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<ezsnack> and you ahve no reason to switch the plotting frame back to eci, you are not seeing what your trajectory is doing with respect to venus
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<ezsnack> so a blind adjust
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Reply to "ezsnack: and you ahve no reason to switch the plotting frame back to eci, you are not seeing what ..."
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<Kaga> Thats… why i pressed VSO so i could see where?
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<ezsnack> after tvi starts you have no reason to ever switch back the plotting frame to eci
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<ezsnack> the manoeuvering frame on the other hand should always be relevant to what you are currently orbiting
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Reply to "Kaga: Not blind adjust, checked VSO and plotted the DV in ECI mode to see how close i got with ..."
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<egg> Please, please, use specific terminology, otherwise you are unintelligible and the conversation goes in circles. I have no idea what ECI mode is supposed to mean. There is a plotting frame, and there is a manœuvring frame, those are two distinct things, you should say which one you are setting to what if you want to be understood.
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<Kaga> earth centered inertialVenus sun orbit
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Reply to "Kaga: earth centered inertialVenus sun orbit"
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<egg> The problem is not the abbreviations!
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Reply to "Nazfib: That's interesting. I'm just now doing a test launch (Atlas-Agena, 230 kg to Venus), and ..."
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<kuzinat0r> Dunno, maybe it's because I'm using the release mechjeb. But it constantly overshoots. It probably spends the right amount of deltaV, but the resulted trajectory goes past the desired periapsis
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<egg> The problem is that there are two things that can be set to VSO or to ECI. Which one are you setting?
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<Kaga> maneouver frame is ECI, plotting frame is VSO, so i could see the flight path
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<egg> OK, good.
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<ezsnack> so the only thing lefts thats wrong is that you launched on a random date, when the window gets close use twp to see the plot again, the more you do it the more accurate
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Reply to "ezsnack: so the only thing lefts thats wrong is that you launched on a random date, when the windo..."
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<Kaga> is it even allowed to have 0.X deviation from planned LAN to actual LAN?
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<ezsnack> yes its not that deep
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<Pimiento> First time using Principia. So far I have my return trajectory to/from Moon and I need to execute the node. I see a button to warp to maneuver but I don't know how to execute it. I think Principia does not execute it, but I cannot find any option on Mechjeb (dev version) to do it either. (I used to execute maneuvers from the Maneuver Planner). Any tip? Thanks !!
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<Vector> thats the way you should be executing principia maneuvers
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<Pimiento> mmh, that is my question. I do not see the option to execute in Mechjeb Maneuver Planner (Only Create Node, and Create Node and Execute). I am restarting the mission again once I reach the same point I will take a screenshot. Thanks !