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…
raptop has joined #principia
raptop has quit [Ping timeout: 190 seconds]
raptop has joined #principia
<queqiao->
⟨.popvapor⟩ Is there any mod that allows you to set auto/unattended course corrections?
<queqiao->
⟨test_account9540⟩ no, because in the presence on principia, nothing can move the unloaded vessel except principia itself
<queqiao->
⟨test_account9540⟩ (but even without principia it's totally unclear how to correctly use engines and spend fuel when the vessel is unloaded, meaning it's parts are not available to that mod)
<queqiao->
⟨test_account9540⟩ * mod. One can't fire the engine of an unloaded vessel.)
<queqiao->
⟨test_account9540⟩ * a mod can
<queqiao->
⟨test_account9540⟩ * which means
<queqiao->
⟨.popvapor⟩ Yeah but aren't orbital parameters just a line in a config file somewhere?
<queqiao->
⟨.popvapor⟩ Couldn't a mod "cheat" by calculating how much fuel would be required for a certain manuever, then editing the orbital parameters and deleting the fuel?
<queqiao->
⟨kuzinat0r⟩ Just cheat yourself into the target orbit then
<queqiao->
⟨kuzinat0r⟩ * then, if you don't wanna play the game
<queqiao->
⟨iso12⟩ Awesome, I love Julia+JuMP - amazingly flexible and easy to use different solvers.
<queqiao->
I have some sequential convex programming codes if you are interested where I've used JuMP for solving low-thrust trajectory optimization problems really quickly. I have to think SCP codes could be quite useful for the ascent guidance problem. Essentially what I think you are doing in mechjeb-like ascent guidance is an MPC-like controller where every few seconds the OCP is resolved to include any perturbations etc. With SCP once the initial...
<queqiao->
... reference solution is found this should allow for warm starting subsequent solves. I'd expect it to converge in a single iteration and be very fast. Have you explored the possibility of using such methods for these problems?
<queqiao->
⟨.popvapor⟩ There's a difference between what I'm talking about and cheating
<queqiao->
⟨Joshua Wood⟩ wooaa careful, around here anything that makes your life easier is synonymous with cheating 🤣
<queqiao->
⟨.popvapor⟩ It's impractical to manage the orbits of a large number of satellites for large solar-system spanning comms networks
<queqiao->
⟨.popvapor⟩ Thats why in real life satellites can do course corrections autonomously
<queqiao->
⟨test_account9540⟩ the game is just not made for that
<queqiao->
⟨test_account9540⟩ when you are in the space center, no physics are calculated for anything beyond the basic orbital movment
<queqiao->
⟨test_account9540⟩ no engines, no fuel, no collisions, no nothing
<queqiao->
⟨Joshua Wood⟩ Fuel is
<queqiao->
⟨test_account9540⟩ Fuel is not spent by engines. Do you mean boiloff? It's a weird workaround
<queqiao->
⟨Joshua Wood⟩ +(fuel cells and boiloff
<queqiao->
⟨Joshua Wood⟩ * boiloff)
<queqiao->
⟨test_account9540⟩ fuel cells, well, not sure how they work
<queqiao->
⟨.popvapor⟩ I mean I know what I'm talking about is possible in KSP, but it's not neccecary since 2-body gravitation will keep orbital parameters the same. I just don't know if orbital parameters in principia are stored the same way
<queqiao->
⟨.popvapor⟩ +stock
<queqiao->
⟨nazfib⟩ > calculating how much fuel would be required for a certain manuever,Difficult, but doable
<queqiao->
> then editing the orbital parametersQuite doable; Principia basically already does this to implement its physics
<queqiao->
> and deleting the fuel?_Extremely_ hard; almost surely never going to happen in Principia. Kerbalism tries to do something like this for electricity, and it makes a whole bunch of simplifying assumptions that don't apply in this case.
<queqiao->
⟨test_account9540⟩ there are no stored orbital parameters in principia
<queqiao->
⟨nazfib⟩ +(it sets the position and veloctity, and KSP calculates the osculating orbital parameters from those)
<queqiao->
⟨test_account9540⟩ just like they don't exist in real life, it's a result of calculations and they are approximate
<queqiao->
⟨Joshua Wood⟩ there has to be some stored somewhere otherwise saving and loading wouldn't work xd
<queqiao->
it has to enter the ram somewhere to be able to be displayed
<queqiao->
you'd need some kind of kerbalism hook to use it's resource consumption system to consume the fuel, similar to fuel cells
<queqiao->
⟨ezsnack⟩ the only thing stored is position and velocity right?
<queqiao->
⟨test_account9540⟩ what is stored is not orbital parameters, it's the positions, masses and velocities of celestials and vessels
<queqiao->
⟨Joshua Wood⟩ all you want to change is the velocity
<queqiao->
⟨.popvapor⟩ that's all you need... velocity is a vector
<queqiao->
⟨test_account9540⟩ yes, principia does that, and it kind of takes over the process so that no other mod can touch it
<queqiao->
⟨test_account9540⟩ we also need to change mass to account for the spent fuel (unless you are doing solar sail...)
<queqiao->
⟨nazfib⟩ The problem is not the updating of the velocity and position, that is actually quite a manageable project (as a part of Principia).
<queqiao->
What is difficult is updating the fuel-containing parts in the vessel; that is something the Principia devs have repeatedly said they're not at all interested in trying to do; you'd need to write a Kerbalism-like mod for that.
<queqiao->
⟨nazfib⟩ * vessel. That
<queqiao->
⟨ezsnack⟩ Why doesnt mj smart ass integrate with principia? The stock sas works fine based on the current reference frame but smart ass aims based on current soi instead of selected reference frame
<queqiao->
⟨Joshua Wood⟩ I'd imagine a completely separate mod would be the best case scenario yeh, one that requires kerbalism and principia to run
<queqiao->
⟨test_account9540⟩ This topic is much larger than orbital corrections. It's the least important part of it.
<queqiao->
The really important missing part is persistent thrust, necessary for ion engines to function...
<queqiao->
Atmospheric drag has been repeateadly discussed, it falls to the same category.
<queqiao->
Solar sail too (not sure it was ever mentioned though)
<queqiao->
⟨Joshua Wood⟩ with certain parts that have a kerbalism consumer added to their configs, which handles removing fuel + mass changes etc.
<queqiao->
calculate dv from straight mass vs engineefficiency*fuel amount, which would be part of the kerbalism consumer attached to specific engines
<queqiao->
it's a whole large mod understaking, i imagine it's _possible_ just not _plausible_
<queqiao->
⟨Joshua Wood⟩ with certain parts that have a kerbalism consumer added to their configs, which handles removing fuel + mass changes etc.
<queqiao->
calculate dv from straight mass vs engineefficiency*fuel amount, which would be part of the kerbalism consumer attached to specific engines
<queqiao->
it's a whole large mod understaking, i imagine it's _possible_ just not _plausible_
<queqiao->
⟨Joshua Wood⟩ * engineefficiency x fuel
<queqiao->
⟨nazfib⟩ Sure, it can be extended much more. But if one's serious about trying to make such a mod, then performing pre-planned maneouvres in the background could be a good place to start. Then at least you don't have to implement trajectory optimization as well as all the other things.
<queqiao->
⟨nazfib⟩ * start experimenting.
<queqiao->
⟨vlood⟩ Talking about "cheaty" solutions on #principia is probably the easiest way to invoke an 🥚⛈️
<queqiao->
⟨kuzinat0r⟩ I know what you feel. That's why I abandoned my geostationary satellites network - they just don't wanna stay where I need them. But I managed to achieve the similar results with much lower orbit height.
<queqiao->
⟨Al₂Me₆⟩ _Petitions egg_unicode for "lightning-rod"_
<queqiao->
⟨Al₂Me₆⟩ * ":lightning-rod:"_
<queqiao->
⟨.popvapor⟩ Is there a guide somewhere for using the navball? I'm having a hard time understanding how to use it outside of a fixed-rotation earth reference frame
<queqiao->
⟨.popvapor⟩ * ecef
<queqiao->
⟨.popvapor⟩ There has to be some mechanism for this though -- because don't isru's already do unattended resource updating?
<queqiao->
⟨.popvapor⟩ Or am i remembering a feature from another mod?
<queqiao->
⟨.popvapor⟩ There has to be some mechanism for this though in stock ksp -- because don't isru's already do unattended resource updating?
<queqiao->
⟨nazfib⟩ They do not in stock KSP. Kerbalism does implement background processing for them, if I remember correctly.
<queqiao->
⟨nazfib⟩ * KSP, as far as I know.
<queqiao->
⟨.popvapor⟩ Gotcha, I must be remembering something else then
<raptop>
unironically, I feel like this is something you should poke the KSA devs about to see if station keeping operations can be added from the start?
<queqiao->
⟨.popvapor⟩ I mean, even if they were to make it a far down the line tech tree node, that would be awesome
<queqiao->
⟨.popvapor⟩ (Especially since truly automated station keeping is a fairly recent technology)
<queqiao->
⟨Joshua Wood⟩ well IRL they have whole teams of people dedicated to it
<queqiao->
lock it behind the 2nd mission control upgrade (level 3) and just say a team of people handles that lol
<queqiao->
⟨_zavian_⟩ If I were going to implement "automated station keeping" in an KSP-like game with an orbital model like KSPs SOI system (rather than a principia like model), I would simply detect this orbit is almost but not quite geo-stationary and correct it to be geo-stationary without bothering with anything like actual station-keeping manoeuvres.
<queqiao->
⟨.popvapor⟩ That's exactly what we've been discussing
<queqiao->
⟨Joshua Wood⟩ it's not needed without principia really :p
<queqiao->
you can get orbital periods within fractions of a second quite easily
<queqiao->
⟨.popvapor⟩ I don't want to do the math right now, but compared to stock ksp how much is n-body going to pull my satellites out of geostationary orbit?
<queqiao->
⟨Joshua Wood⟩ a lot afik xd
<queqiao->
⟨.popvapor⟩ Plus, isn't there gravity in principia due to the uneven shape of bodies (forgot what thats called)
<queqiao->
⟨.popvapor⟩ Pertubations i think
<queqiao->
⟨_zavian_⟩ No it isn't, since with principia, most geo-stationary orbits aren't actually stable and need station-keeping manoeuvres.
<queqiao->
⟨_zavian_⟩ But my point is KSA isn't likely to implement non-cheaty station-keeping manoeuvres. They would be much more likely to just cheat correct a near geo-stationary orbit to one which is geo-stationary, since they aren't likely to actually implement a principia level sim.
<queqiao->
⟨Joshua Wood⟩ i would have said the same about trajectories and FAR :p
<queqiao->
⟨nazfib⟩ The Sun and the Moon really strongly pull you out of the plane of the equator over time; GEO comm sats budget around 50 m/s of Δv per year on this. Besides this, the uneven gravity of the Earth pulls you in the East/West direction; the magnitude of this effect strongly depends on the longitude where you want to keep the satellite, but this can add another 10 m/s per year to your Δv budget.