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->
⟨Jexa Jexins⟩ Anyone got any good tutorials for principia? just started wanting to go beyond LEO and when i watch people they dont really explain what they are doing so i have no clue
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⟨Stonesmile⟩ What exactly is it you want to do?
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⟨Jexa Jexins⟩ im trying to plot a flyby/ impact got 3.2k dleta but cant select it or anything and not sure how to calculate lan etc
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⟨Stonesmile⟩ I would use the LunarTransferplanner (on CKAN) to get the launch time and use PVG for the ascent as normal with the time/inclination that gives you
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⟨Stonesmile⟩ * LunarTransferPlanner
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⟨Jexa Jexins⟩ okay so that will get me into orbit at the correct inclantion what about getting to the moon?
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⟨Stonesmile⟩ Create a manoeuvre with 3150 m/s prograde and tune the time to get an impact
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⟨Stonesmile⟩ +(in the normal reference frame)
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⟨Jexa Jexins⟩ will the patched conics come up?
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⟨Stonesmile⟩ patched conics? You create the burn in Earth Inertial and then switch to Lunar to see the approach and tune it
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⟨Jexa Jexins⟩ intersting let me get to a specifid orbit and ill see what i can see
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⟨test_account⟩ Whatever you do, don't use the patched conics. They can be switched on in principia, but don't
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⟨test_account⟩ They can only mislead, use principia orbit history to see what the orbit looks like and trajectory forecast (magenta) / plan (dashed line) to see where the ship is going to
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⟨Cirelion⟩ Would the principia stock tutorial be worthwhile in order for me to learn prinicipia in RP-1? Or is there another place I should check out for a starter guide?
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⟨test_account⟩ Principia is the same in stock and RP1, so yes, it should be a good starter guide
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⟨Stonesmile⟩ maybe? A good idea might be to do stuff in sandbox before doing it in a RP-1 save
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⟨Jexa Jexins⟩ okay what does this mean?
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⟨Cirelion⟩ I don't really enjoy sandbox, I like to have a clear goal. I'll just play fast and loose with saves for my first runthrough I think.
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⟨test_account⟩ flight time means how long until you reach the moon, default is 4 days and usually shouldn't be changed
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⟨test_account⟩ then you just press warp or add alarm and launch due east at that time
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⟨Stonesmile⟩ ⟪Jexa Jexins⟫ okay what does this mean? ⮪ If you launch now, set inclination to -45°. If you want to launch directly east; wait for 7h9m (that's the alarm/warp)
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⟨Jexa Jexins⟩ okay ill give it a go, can i use mechjeb pvg?
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⟨Jexa Jexins⟩ just lauch at current inc?
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⟨Stonesmile⟩ Yep, PVG current inclination after 7h
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⟨Jexa Jexins⟩ can you guess a menuver or do you need some sort of planning via a node to get a decent encounter? like aim at the moon and go is not a viable solution for early goes?
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⟨Kalpyy⟩ Create the manuever, add 3150 m/s, and then just increase/decrese the manuever start time untill you get the moon periapsis you want
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⟨Kalpyy⟩ and make sure to increase the plan lenght to 5-6 days so you can actually see what you aer doing
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⟨Jexa Jexins⟩ but what if you cant creat manuevers yet...
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⟨Jexa Jexins⟩ caveman style
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⟨Jexa Jexins⟩ but what if you cant create manuevers yet...
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⟨Cirelion⟩ Quick save quick load lol
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⟨test_account⟩ Actually you can create a maneuver in Principia even if you don't have the tracking station upgrade (or mission control)
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⟨test_account⟩ The only issue is that it won't be shown on the navball
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⟨test_account⟩ However, if the maneuver is only prograde (no other components), it's also not a big issue
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⟨test_account⟩ You'll have to execute such a maneuver manually though, caveman style 😛
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⟨Jexa Jexins⟩ interesting ill give it a go...
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⟨Kalpyy⟩ and make sure you're using MEO so you can actually see your trajectory wrt to the moon
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⟨test_account⟩ Be careful with this. First of all there is plotting frame and maneuvering frame, and maneuvering frame should be ECI. Second, it might be better to start rough planning in ECI and then switch to MEO or MCI for precise tuning.
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⟨Jexa Jexins⟩ can create node by clicking on the line??
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⟨Jexa Jexins⟩ * cant
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⟨Jexa Jexins⟩ ive upgraded my tracking center now
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⟨Jexa Jexins⟩ nvm found "flight plan"
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⟨test_account⟩ clicking on the line doesn't work, only thing you can do is right click periapsis or other such points on the line to make them stick
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⟨test_account⟩ i just right clicked the periapsis on the magenta line
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⟨test_account⟩ * apoapsis
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⟨Jexa Jexins⟩ ohh i see what your saying
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⟨test_account⟩ you will see a lot of useful info
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⟨Jexa Jexins⟩ only 26 overbudget which i can do with rcs
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⟨Jexa Jexins⟩ nvm changing time now only 3
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⟨Jexa Jexins⟩ dope i get it now
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⟨test_account⟩ with that normal component you'll need maneuver nodes to execute the maneuver
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⟨test_account⟩ but you have it, so click "show on navball"
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⟨Jexa Jexins⟩ should i aim to burn 50% each side aswell?
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⟨Jexa Jexins⟩ if the burn is 40seconds should i aim to burn 20s eahch side of the node
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⟨test_account⟩ no
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⟨Stonesmile⟩ No. Principia nodes are from when ignition should happen to when you should shut it off
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⟨Jexa Jexins⟩ right so on 0
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⟨test_account⟩ "to when you should shut it off" is not precise due to variance, only the starting time is precise
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⟨Stonesmile⟩ ⟪test_account⟫ "to when you should shut it off" is not […] ⮪ Correct. There is likely some small variance so looking at the map view is best
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⟨Jexa Jexins⟩ yeah was gonna say as my solid has burn time of 44 but pincipia is saying 32 seconds...
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⟨test_account⟩ solids are pain to use with principia
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⟨test_account⟩ First of all, principia can only plan the active engine, but how can you make a solid engine active?
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⟨Jexa Jexins⟩ yeah im seeing the pain bit rn...
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⟨test_account⟩ (i think pressing activate will make it burn)
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⟨test_account⟩ second, solid burn time is reported differently in MJ and elsewhere, due to thrust curve I suppose
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⟨Stonesmile⟩ For solids the usual way is to use "instant impulse" and burning half of the time before the node
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⟨test_account⟩ But half of which time?
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⟨test_account⟩ I had to record solid burn in mechjeb flight recorder and find the midpoint in terms of dV expended for my unguided TLI probes
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⟨test_account⟩ Then there is also a small issue that principia instant impulse isn't instant, it can be 2 seconds or so, so this also needs to be taken into account
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⟨test_account⟩ So it's not easy to hit the moon unguided with solids
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⟨Kalpyy⟩ ⟪Jexa Jexins⟫ yeah was gonna say as my solid has burn […] ⮪ move the node back/forward and increase dV to make it accurate to what you have, although as I understand it this only really creates a buffer of like 5-10 m/s
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⟨Jexa Jexins⟩ missed with my solid but no too far off
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⟨test_account⟩ that's the expected result )
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⟨test_account⟩ hitting with a solid is unexpected
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⟨nvv⟩ Hi, I'm trying to do a free return trajectory (to the moon), but I couldn't find any resources except a thread that I didn't find that helpful. If anyone can help me out a bit I'll appreciate it
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⟨Itspats (solid lv enthusiast)⟩ ⟪nvv⟫ Hi, I'm trying to do a free return […] ⮪ same
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⟨itsRyan⟩ What part are you having trouble with? The basic idea is to aim in front of the Moon's path and then tweak your trajectory until it throws you back to the desired Earth Pe. Switching reference frames between MCI and ECI is helpful. MEO can also be helpful, but I don't believe that one gives you precise Pe for the Earth return.
<queqiao->
⟨itsRyan⟩ One thing that might be tripping you up is that a typical free-return from the Moon is too high for the flyby contract. The real life Apollo missions course corrected out of a free return trajectory after TLI.
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⟨nvv⟩ ⟪itsRyan⟫ What part are you having trouble with? […] ⮪ How far in front of the moon would the trajectory normally be?
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⟨itsRyan⟩ It's been a while since I've done one, but as I recall if you're close to in plane, with a 7-8 day round trip, it would be about a 15 Mm perilune.
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⟨itsRyan⟩ But there are lots of factors, so you'll just have to play with it in your game.