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…
_whitelogger has joined #principia
<queqiao--> <K​ag​a> now im able to bring TLI liquid engines to LEO, do i still use instant impulse as the option for burn? https://media.discordapp.net/attachments/480397772248580098/1369125506955477142/image.png?ex=681ab8fd&is=6819677d&hm=04ef7c6eca7646b0e68d71035a59d7a1b5f622818bdb2c44f5a2c7f890d78827&
<queqiao--> <J​ak​at​ha​n> No, liquid engines you can use the actual burn integrator
<queqiao--> <K​ag​a> I just have to “execute node” and it should work right?
<queqiao--> Reply to "b​eb​: y'all ever code a ground tracks sim to plan out your molniya constellations"
<queqiao--> <T​iv​ec​> No but now I kind of want it 😄
<queqiao--> Reply to "K​ag​a: accidentally made a sun synchronous-ish orbit on the moon"
<queqiao--> <T​iv​ec​> I want those orbit properties
<queqiao--> Reply to "K​ag​a: I just have to “execute node” and it should work right?"
<queqiao--> <T​iv​ec​> Yes but to have «active engine» working you must have it staged active.
<queqiao--> <T​iv​ec​> How hard is Earth-Moon L2 to achieve, and what kind of precision are we talking here? Is it stable-ish or will it drift out of the orbit often?
<queqiao--> <T​iv​ec​> i was thinking about setting one up as a relay for the dark side of the moon
<queqiao--> Reply to "T​iv​ec​: I want those orbit properties"
<queqiao--> <K​ag​a> its by accident but the orbital inc is retrograde like 110deg
<queqiao--> Reply to "K​ag​a: its by accident but the orbital inc is retrograde like 110deg"
<queqiao--> <T​iv​ec​> accidental orbits are best orbits 😄
<queqiao--> Reply to "T​iv​ec​: accidental orbits are best orbits 😄"
<queqiao--> <K​ag​a> sadly this is only sim so, i might not be able to replicate it again
<queqiao--> <T​iv​ec​> my french is unfortunately... lacking
<queqiao--> <T​iv​ec​> but i did manage to set up a L2 capture, though I don't know how to get it to "stick", it goes out of there immediately after like one or two orbits unless i constantly adjust. https://media.discordapp.net/attachments/480397772248580098/1369201174187741235/image.png?ex=681aff76&is=6819adf6&hm=8c430a4901d55aaa1641534c1910f679e3d8543d3911a4190697171a9a133b76&
<queqiao--> <T​iv​ec​> it's not quite L2 though
<queqiao--> Reply to "T​iv​ec​: my french is unfortunately... lacking"
<queqiao--> <T​iv​ec​> so moon L2 is almost impossible to maintan?
<queqiao--> <e​gg​> (From the pinned book.)
<queqiao--> <e​gg​> Who said anything about L2? This is about a sun-synchronous orbit.
<queqiao--> <T​iv​ec​> ohhh
<queqiao--> <T​iv​ec​> i read "J2" and thought that was L2.. my brain is dumb today
<queqiao--> <e​gg​> As for trajectories around L1, L2, or L3, those are unstable, so fundamentally they won’t stick.
<queqiao--> <T​iv​ec​> right, but it's possible to create an L2 orbit that last for a while at least. then i can plan the next station keep manoeuvre and add that to the alarm clock
<queqiao--> <T​iv​ec​> bloody heck, i wish i had enabled stage lock
<queqiao--> Reply to "T​iv​ec​: right, but it's possible to create an L2 orbit that last for a while at least. then i can..."
<queqiao--> <D​am​ie​n> It varies a bit but you're looking at stationkeeping once a month in EML2
<queqiao--> <D​am​ie​n> And once every 1-2 years in Sun- Earth L2
<queqiao--> <D​am​ie​n> Same figures for L1
<queqiao--> <T​iv​ec​> not too shabby then. but i do need to have reaction wheels on this satellite core, it's way too fidgety using RCS to rotate...
<queqiao--> <T​iv​ec​> though i don't understand where on the orbit i'm supposed to do the station keep burns
<queqiao--> <K​ag​a> Are lagrange points meant for some sort of special mission in the game or is it just there as a feature
<queqiao--> <e​gg​> The question is strange. They just are there, because they are a consequence of the laws of physics. We couldn’t prevent them from being there if we wanted.
<queqiao--> <e​gg​> They are not a separate feature. Now, the reference frame with the equipotentials that makes them easier to see, that is a feature. But the points themselves just fall out of the equations.
<queqiao--> <K​ag​a> Why is it strange? I just wanna know when to use lagrange points for some types of missions/ what case/scenario should i use it for
<queqiao--> <e​gg​> The strangeness is in the use of the verb to mean, and of the noun feature. You just cannot help but have them if you have 𝑛-body gravitation, they are not somehow a separate feature.
<queqiao--> <e​gg​> Now, what are they good for is a different question.
<queqiao--> <e​gg​> Which is not that much, really. But they are a useful landmark when planning low-energy transfer.
<queqiao--> Reply to "b​eb​: y'all ever code a ground tracks sim to plan out your molniya constellations"
<queqiao--> <C​la​ye​l> woah, pretty cool! send source!
<queqiao--> <B​ut​ch​er​> I tried E-M L2 commsats for a while but they're finicky because of the instabilities.
<queqiao--> <B​ut​ch​er​> DRO seemed like a more stable long term far side solution, if not quite as high availability.
<queqiao--> <T​iv​ec​> DRO?
<queqiao--> <e​zs​na​ck​> Distant retrograde orbit
<queqiao--> <T​iv​ec​> how do you reach that kind of orbit
<queqiao--> <e​zs​na​ck​> I think its just a retrograde orbit at high altitude
<queqiao--> <h​ay​so​x> Regarding station keeping, do people just use the predicted trajectory and then set an alarm or something for when you need to go back in and adjust the orbit?
<queqiao--> <e​zs​na​ck​> i never needed it once so far lol
<queqiao--> <T​iv​ec​> i'm trying to do a suicide burn style brake on moon impact, and the burn finishes at like 5km up, which means it takes a lot more than 200m/s to brake and land safely. any recommendations here? how do i manage the planning for it?
<queqiao--> <e​zs​na​ck​> aim for 0m/s impact
<queqiao--> <T​iv​ec​> will i have time to zero out the horizontal speed though?
<queqiao--> <e​zs​na​ck​> and increase the prediction accuracy on the flight plan to atleast centimeters
<queqiao--> <T​iv​ec​> oh, that is probably a good plan
<queqiao--> Reply to "T​iv​ec​: will i have time to zero out the horizontal speed though?"
<queqiao--> <e​zs​na​ck​> idk what you mean, your braking stage should take all your speed and leave you at a standstill as close to the surface as possible :v
<queqiao--> <e​zs​na​ck​> then you do terminal descent on generics
<queqiao--> <T​iv​ec​> i do come in at a bit of an angle though, so...
<queqiao--> <e​zs​na​ck​> it doesnt matter, you are burning retrograde in mcmf
<queqiao--> <e​zs​na​ck​> aka you are canceling all your velocity relative to the surface
<queqiao--> <T​iv​ec​> right
<queqiao--> <T​iv​ec​> okay, we'll see with 25m/s
<queqiao--> <e​zs​na​ck​> Btw to get 0 just alternate messing with the timing and the dv
<queqiao--> <T​iv​ec​> dropped me at 4.4km
<queqiao--> <e​zs​na​ck​> You stopped moving so high? :v something is definitely off
<queqiao--> <T​iv​ec​> i think i can tune it with more tweaking, i just didn't have much time 😄
<queqiao--> <e​zs​na​ck​> It should not be off by that much tho
<queqiao--> <T​iv​ec​> i might have something wrong, let me play with the node a bit
<queqiao--> <T​iv​ec​> it's just that my save is 2 minutes before burn 😄 don't have that much time to play around
<queqiao--> <T​iv​ec​> i wouldn't call it periapsis 😄
<queqiao--> <T​iv​ec​> but i'll roll with it
<queqiao--> <T​iv​ec​> nope, that made things worse. dropped me at 5.7km and started spinning because speed was nulled out and the node decided to move heh
<queqiao--> Reply to "T​iv​ec​: it's just that my save is 2 minutes before burn 😄 don't have that much time to play ar..."
<queqiao--> <e​zs​na​ck​> You can plot with the game paused
<queqiao--> Reply to "T​iv​ec​: i wouldn't call it periapsis 😄"
<queqiao--> <e​zs​na​ck​> Tuat is a periapsis tho, it means that you are stopping before getting to the surface
<queqiao--> <T​iv​ec​> pausing brings up menus and makes it impossible to control camera...
<queqiao--> <e​zs​na​ck​> The menu can be moved and you can setup the camera in a comfortable place before pausing :v
<queqiao--> <T​iv​ec​> yeah
<queqiao--> <T​iv​ec​> seems like it wants to flip the thing over when i get to the hover point, have to hit abort node execution if i get to slow
<queqiao--> <e​zs​na​ck​> You need to fire manually
<queqiao--> <T​iv​ec​> right, okay. hopefully i'm exact enough...
<queqiao--> <e​zs​na​ck​> Also if you are late you can burn rcs to act as throttle. If you are early you cant do much
<queqiao--> <T​iv​ec​> i almost made it. 40m/s this time on impact, so.. will have to replan. again 😄
<queqiao--> <T​iv​ec​> how am i going to do this live and succeed...
<queqiao--> <e​zs​na​ck​> How far are you stopping from the surface is what matter, ideally sub 500m :v dont forget to set radar altitude instead of msl
<queqiao--> <T​iv​ec​> yeah, hoping for < 500m this time
<queqiao--> <T​iv​ec​> was at 1km, so i'm getting closer
<queqiao--> <T​iv​ec​> also, i think i need to have some engine that isn't ullaged for the brake stage :/
<queqiao--> <e​zs​na​ck​> Btw to get 0ms impact step by step:
<queqiao--> <e​zs​na​ck​> -Check the initial impact, create a braking node of exactly that much
<queqiao--> <e​zs​na​ck​> -Move the timing back and forth till you find the moment at which the impact speed is minimal
<queqiao--> <e​zs​na​ck​> -add this impact speed to your braking dv
<queqiao--> <e​zs​na​ck​> -rinse and repeat
<queqiao--> Reply to "T​iv​ec​: also, i think i need to have some engine that isn't ullaged for the brake stage :/"
<queqiao--> <e​zs​na​ck​> Just need strong enough thruster that the ullage in instantaneous
<queqiao--> <T​iv​ec​> right, thrusters are NOT strong enough lol
<queqiao--> <B​ut​ch​er​> I use Kos for all this. :lul: https://cdn.discordapp.com/emojis/911993888611393587.png
<queqiao--> <e​zs​na​ck​> You need a good script to automate this lol
<queqiao--> <T​iv​ec​> Can I hide the predicted impact and just show planned impact?
<queqiao--> Reply to "e​zs​na​ck​: You need a good script to automate this lol"
<queqiao--> <B​ut​ch​er​> https://youtu.be/0H6P1e7vwMU
<queqiao--> <B​ut​ch​er​> Seems to work.
<queqiao--> <e​zs​na​ck​> Pin the planned impact and then uncheck unpinned markers
<queqiao--> <T​iv​ec​> unfortunately if the planned impact becomes a periapsis, the other one disappears...
<queqiao--> Reply to "B​ut​ch​er​: https://youtu.be/0H6P1e7vwMU Seems to work."
<queqiao--> <e​zs​na​ck​> Impressive accuracy
<queqiao--> Reply to "T​iv​ec​: unfortunately if the planned impact becomes a periapsis, the other one disappears..."
<queqiao--> <e​zs​na​ck​> Yea thatsa annoying af 🤣 🤣
<queqiao--> Reply to "B​ut​ch​er​: https://youtu.be/0H6P1e7vwMU Seems to work."
<queqiao--> <e​zs​na​ck​> does it perform as good when the angle to the surface is less than 10deg tho? :v
<queqiao--> <T​iv​ec​> this time i had an expected periapsis at the predicted impact, 0m/s, and it still dropped me off at over 1km so uh... not sure how this is supposed to be done at all, heh.
<queqiao--> Reply to "T​iv​ec​: this time i had a planned periapsis at the predicted impact, 0m/s, and it still dropped m..."
<queqiao--> <e​zs​na​ck​> consider that the ullage is taking speed away and reducing the mass, so its effectively doing double work in changing the burn, so you need to delay a little bit, remember you can always burn rcs to compensate being late
<queqiao--> Reply to "e​zs​na​ck​: does it perform as good when the angle to the surface is less than 10deg tho? :v"
<queqiao--> <B​ut​ch​er​> Yeah works for most angles you can reasonably approach from
<queqiao--> <e​zs​na​ck​> the "active engines" button considers the active engine with the current craft mass, if the mass changes the prediction is not relevant anymore, its gonna be slightly off
<queqiao--> <B​ut​ch​er​> ullage shouldn't be that much difference tbh
<queqiao--> <T​iv​ec​> hrm, okay, will do a slighly later burn
<queqiao--> <T​iv​ec​> like, a second or so maybe
<queqiao--> Reply to "B​ut​ch​er​: ullage shouldn't be that much difference tbh"
<queqiao--> <e​zs​na​ck​> not that much but can be 500m tbf
<queqiao--> <B​ut​ch​er​> But also, I consider anything under 1 km at the end of main braking burn "good"
<queqiao--> <e​zs​na​ck​> i live on low margins so its 300-500 or bust xd
<queqiao--> <B​ut​ch​er​> Trying to stop your main engines at 50m is likely to cause lithobraking if the performance fluctuates at all.
<queqiao--> <B​ut​ch​er​> That vid is 350m stop and needs a little over 30 m/s for final descent, I normally plan more like 100 m/s
<queqiao--> <e​zs​na​ck​> btw theres a trick that can be used together with eyeball mk2, the MJ landing prediction
<queqiao--> <e​zs​na​ck​> it is wildly wrong but you can try to converge the altitude going to 0 and the suicide burn timer going from negative to 0 to happen at the same moment by burning rcs
<queqiao--> <T​iv​ec​> wow. okay uh... so, i started ullage (which takes ~2 seconds) on burn time and that was the difference between 700m/s impact 😄
<queqiao--> <e​zs​na​ck​> (you still rely on principia to now when to ignite tho)
<queqiao--> <T​iv​ec​> so ullage at 2 seconds prior to ignition, and pray.
<queqiao--> <T​iv​ec​> oh btw, ignition. is that supposed to be "engine is now burning" or does that include spin up?
<queqiao--> <e​zs​na​ck​> ehehe good question, idk but it can definitely be off by 1-2 seconds
<queqiao--> <T​iv​ec​> well, now i don't start early enough at all..
<queqiao--> Reply to "B​ut​ch​er​: https://youtu.be/0H6P1e7vwMU Seems to work."
<queqiao--> <k​uz​in​at​0r​> Interesting solar panels orientation
<queqiao--> <T​iv​ec​> 520m this time, hit too hard and rolled, but hey
<queqiao--> Reply to "k​uz​in​at​0r​: Interesting solar panels orientation"
<queqiao--> <B​ut​ch​er​> Yeah, 😬
<queqiao--> Reply to "k​uz​in​at​0r​: Interesting solar panels orientation"
<queqiao--> <e​zs​na​ck​> oh my oh my i didnt even realize 🤣
<queqiao--> <T​iv​ec​> yikes, yes. those panels... Erika starts playing in the background
<queqiao--> <T​iv​ec​> i soft landed!
<queqiao--> <T​iv​ec​> so i think the best way for me on this is to plan for an impact with around 25m/s, seems to deposit me around 500m.
<queqiao--> <T​iv​ec​> so uhm... if i have loaded a sim save, how do i get back to VAB? or do i just hit space center when done, since i don't have a revery option now
<queqiao--> Reply to "T​iv​ec​: so i think the best way for me on this is to plan for an impact with around 25m/s, seems ..."
<queqiao--> <e​zs​na​ck​> dont forget that you can achieve 25m/s in more ways, it can be not enough braking dv and correct timing or correct dv and too early or too late timing :v
<queqiao--> <T​iv​ec​> true, but if i am off by too much time-wise i slam the surface,
<queqiao--> <e​zs​na​ck​> try also from a different angle to the surface of the moon to see if its still true :v
<queqiao--> <T​iv​ec​> right, sideways might not be the best option for me, for the actual mission i'm going to aim for a much more vertical approach, should help killing the speed too
<queqiao--> Reply to "e​zs​na​ck​: oh my oh my i didnt even realize 🤣 now i cant unsee"
<queqiao--> <B​ut​ch​er​> Nor did I when I built it. :p
<queqiao--> Reply to "T​iv​ec​: right, sideways might not be the best option for me, for the actual mission i'm going to ..."
<queqiao--> <e​zs​na​ck​> actually more horizontal is easier cuz timing is not critical, you can stop at any point that your trajectory is below 1km which is a bigger time window the more horizontal the trajectory is
<queqiao--> <T​iv​ec​> ah i see
<queqiao--> <T​iv​ec​> holy shoot, uncrewed moon landing is 250 applicants? don't mind if I do!
<queqiao--> Reply to "C​la​ye​l: woah, pretty cool! send source!"
<queqiao--> <b​eb​> https://youtube.com/@alfonsogonzalez-astrodynam2207?si=CX7JdCG3-hdlYDQr this guy's whole channel is a gold mine. I started my project heavily based off of his and then tweaked it for what I needed
raptop has quit [Ping timeout: 190 seconds]
raptop has joined #principia
_whitelogger has joined #principia
<queqiao--> <p​in​ec​on​ez​> very comfy kitty
<queqiao--> <M​ax​si​ma​l> Yeah he loves sleeping in the grandpa recliner.
<queqiao--> Reply to "k​uz​in​at​0r​: Interesting solar panels orientation"
<queqiao--> <s​ic​he​lg​ai​ta​> Must have been inspired by the movie Iron Sky.
<queqiao--> <M​ax​si​ma​l> Poor cats with eye infections, always feel so bad for them
raptop has quit [Ping timeout: 198 seconds]
raptop has joined #principia
<queqiao--> <B​ut​ch​er​> He's a bit feral
raptop has quit [*.net *.split]
raptop has joined #principia
raptop has quit [*.net *.split]
raptop has joined #principia
<queqiao--> Reply to "b​eb​: https://youtube.com/@alfonsogonzalez-astrodynam2207?si=CX7JdCG3-hdlYDQr this guy's whole ..."
<queqiao--> <C​la​ye​l> i meant like source code