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…
<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
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<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
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<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
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<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
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<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
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<queqiao-> ⟨E​ggElectron⟩ How do you add a maneuver to the flight plan to be executed at the moment you cross the earth's equator in LEO?
<queqiao-> ⟨S​tonesmile⟩ By sliding the start time slider? There is currently no option to attach a manoeuvre to a point in the orbit
<queqiao-> ⟨S​tonesmile⟩ What is the goal of this manoeuvre?
<queqiao-> ⟨E​ggElectron⟩ Geostationary transfer
<queqiao-> ⟨S​tonesmile⟩ Ah, then it is easier to make sure that the Ap is at the An/Dn node, rather than the burn itself
<queqiao-> ⟨E​ggElectron⟩ I realized Mechjeb cant make a principia maneuver node at the ascending node, so was wondering if theres another way to get the node exactly at the right spot besides eyeballing it
<queqiao-> ⟨E​ggElectron⟩ yes! you are right
<queqiao-> ⟨E​louda⟩ you can just look at the time to the AN/DN node an enter that into the time field?
<queqiao-> ⟨E​ggElectron⟩ thats what I ended up doing just now in simulation. still kinda curious if theres a way to know how to put the node at the moment you cross the equator. If I didn't have a geostationary orbit contract, there would be no visual marker to line my ap with
<queqiao-> ⟨E​louda⟩ you can just look at the time to the AN/DN node and enter that into the time field? (edited)
<queqiao-> ⟨S​tonesmile⟩ An/Dn should still exist I think?
<queqiao-> ⟨E​louda⟩ it might not show them in some frames of reference
<queqiao-> ⟨E​louda⟩ but you should be able to get time to them from MJ or KER iirc
<queqiao-> ⟨E​louda⟩ the other way to do it is to open the orbit analyzer, and look at the post burn inclination as you adjust the time position until you find exactly what you want
<queqiao-> ⟨E​ggElectron⟩ I see the An of my current LEO but not necessarily the target GEO
<queqiao-> ⟨E​louda⟩ will be the same if you burn at AN/DN
<queqiao-> ⟨E​ggElectron⟩ ahhh, the orbit analyzer yes
<queqiao-> ⟨S​tonesmile⟩ Keep in mind that the burn isn't instant, so even with that time it is slightly wrong
<queqiao-> ⟨E​ggElectron⟩ how do you convert the t minus to time from initial
<queqiao-> ⟨E​ggElectron⟩ ?
<queqiao-> ⟨S​tonesmile⟩ There is no easy way, you have to simulate it to know for sure what will happen
<queqiao-> ⟨S​tonesmile⟩ good news; the prediction is that sim
<queqiao-> ⟨E​louda⟩ yep, thats one of the best parts about principias maneuver plotter, is that it includes all that and isnt just instant impulse (unless you set it to be)
<queqiao-> ⟨E​ggElectron⟩ okay, Im just trying to get the node to be at the equator though
<queqiao-> ⟨S​tonesmile⟩ don't you want the apogee above the equator?
<queqiao-> ⟨E​ggElectron⟩ yes
<queqiao-> ⟨E​ggElectron⟩ thank you for the responses
<queqiao-> ⟨E​ggElectron⟩ If I know Im crossing the equator in 30 seconds, and I am currently 10 minutes into the flight, then entering 10minutes 30 seconds into the maneuver would put it at the moment I cross the equator?
<queqiao-> ⟨S​tonesmile⟩ It would be close, yes, but since the burn takes time, that introduces errors. If you instead look at the manoeuvre prediction and see where that Ap ends up, you can tune the time from that
<queqiao-> ⟨E​louda⟩ you can also rebase it which will make the time relative to your current position
<queqiao-> ⟨B​utcher⟩ REbase is magic.
<queqiao-> ⟨B​utcher⟩ Rebase is magic. (edited)
<queqiao-> ⟨E​ggElectron⟩ I have no idea how to do that but it sounds amazing.
<queqiao-> ⟨E​ggElectron⟩ I will look for the rebase thing. Thank you all!
<queqiao-> ⟨E​ggElectron⟩ I will look for the rebase thing. And will use my eyeballs and principia's awesome visual prediction displays. Thank you all! (edited)
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<_whitenotifier> [Principia] HugoBruins opened issue #3037: Create a warning DLL for downloading the mod from the wrong place - https://git.io/Jnie9
<queqiao-> ⟨Z​eusbeer⟩ I created your reminder
<queqiao-> ⟨Z​eusbeer⟩ (in a bit of shame)
<queqiao-> ⟨Z​eusbeer⟩ (but it's for the better)
<queqiao-> ⟨Z​eusbeer⟩ oh can I suggest a feature
<queqiao-> ⟨Z​eusbeer⟩ Being able to select a stage instead of 'active engines' and 'rcs' only for planning maneuvers
<queqiao-> ⟨Z​eusbeer⟩ For example if someone plans to use a solid fuel kickstage for a second burn, like Voyager and New Horizons, it's a bit tricky to time with an instant impulse for the second burn.
<queqiao-> ⟨Z​eusbeer⟩ Also usefull for making the entire maneuver sequence in one go
<queqiao-> ⟨B​utcher⟩ I don't think egg wants to get into KSP stage handling. :-p
<queqiao-> ⟨D​amien⟩ he'll do anything if you can trick him into thinking it's 'developmentally interesting'
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<queqiao-> ⟨Z​eusbeer⟩ I mean, he must be snack on the current stage info somewhere
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<queqiao-> ⟨B​utcher⟩ I think principia just checks for engines which are active. Hence being sketchy for solids.
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<queqiao-> ⟨b​ongotastic⟩ Stage detection seems to be a real bane for anyone wandering in thinking it will be easy/fun.
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<queqiao-> ⟨D​RVeyl⟩ What we really need is someone to wander in thinking it's going to absolutely suck, and be stubborn enough to see it through anyway!
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ That first part is not much of a problem
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ That first part is not much of a problem atleast (edited)
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<queqiao-> ⟨S​ir Mortimer⟩ I still hope for an open source KSP after the final release. Not sure who would hold it together
<queqiao-> ⟨D​amien⟩ egg will
<queqiao-> ⟨D​amien⟩ open source ksp confirmed for the next principia release
<UmbralRaptop> I'm pretty sure that would be Principia + FAR + some minimal rocket handling logic
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ 🤔 albumen is a good binder
<queqiao-> ⟨A​l2Me6⟩ How does Principia handle angular momentum with solid rocket motors?
<queqiao-> ⟨v​evladdd⟩ Linuxgurugamer
<queqiao-> ⟨e​gg⟩ An interesting question, and a complicated one; I am not sure what the answer *should* be, I found a series of articles arguing about the effect of jet damping
<queqiao-> ⟨A​l2Me6⟩ I ask because I'm testing a spin-stabilized lunar impactor, which began to precess wildly as soon as I ignited the motors (seemed like it was losing angular momentum?)... evidently I didn't spin up enough, but the behavior still surprised me.
<queqiao-> ⟨e​gg⟩ I think for solids what we currently do is accurate
<queqiao-> ⟨e​gg⟩ we do the same for liquids which might be sketchy
<queqiao-> ⟨e​gg⟩ ah no we don’t but weirdly https://github.com/mockingbirdnest/Principia/issues/2508
<queqiao-> ⟨e​gg⟩ the idea is the fuel of the SRB has angular momentum, and the internal structure and operation of an SRB doesn’t allow it to be transferred to the rocket as the gases go out
<queqiao-> ⟨e​gg⟩ essentially, you get spinning exhaust
<queqiao-> ⟨e​gg⟩ but in a liquid engine, the angular momentum will get transferred to the rocket via the pipes and injector (if the fuel spins through the injector you probably don’t have an injector anymore)
<queqiao-> ⟨A​l2Me6⟩ Ok, that makes sense.
<queqiao-> ⟨e​gg⟩ @Al2Me6 so to the best of our knowledge this effect is real; it has a name, « jet damping »
<queqiao-> ⟨e​gg⟩ Principia: making you discover exciting and sometimes rather obscure bits of rocketry from first principles
<raptop> Fortunately, Kerbals use [REDACTED] to minimize torques. [REDACTED] also makes deep throttling vastly easier and more efficient.
<queqiao-> ⟨A​l2Me6⟩ You've probably seen this, but Googling led me to https://arc.aiaa.org/doi/pdf/10.2514/1.3852... time to read.
<queqiao-> ⟨e​gg⟩ yup
<queqiao-> ⟨e​gg⟩ See also « A re-evaluation of jet damping » and « Comments on “A Re-Evaluation of Jet Damping” »
<queqiao-> ⟨e​gg⟩ also « Jet damping of a solid rocket - theory and flight results »
<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
<queqiao-> ⟨B​utcher⟩ Raptop, 0.01% deep throttling is completely realistic. 👌
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<queqiao-> ⟨§​κyℓαr ♀⟩ As a community we really need to make an open ksp. I imagine it would either be made with godot or its own engine?
<raptop> aaaaaa
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ I doubt godot, Skylar
<raptop> I'd bet that godot or the like would have float problems that would mean recapitulating a lot of silliness in KSP
<queqiao-> ⟨§​κyℓαr ♀⟩ Yeah
<queqiao-> ⟨§​κyℓαr ♀⟩ Oh? someone is already working on a project like this?
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ For a few years
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ Also, I've linked it to you before I think
<queqiao-> ⟨§​κyℓαr ♀⟩ I have the memory of a toaster if you did.
<queqiao-> ⟨§​κyℓαr ♀⟩ What license is it under?
<queqiao-> ⟨§​κyℓαr ♀⟩ lol
<queqiao-> ⟨§​κyℓαr ♀⟩ I
<queqiao-> ⟨§​κyℓαr ♀⟩ honestly just don't remember that
<queqiao-> ⟨§​κyℓαr ♀⟩ my memory really is comparible to the best of toasters
<queqiao-> ⟨§​κyℓαr ♀⟩ actually
<queqiao-> ⟨§​κyℓαr ♀⟩ probably worse.
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ MIT license
<queqiao-> ⟨§​κyℓαr ♀⟩ ew, well, at least its a free license.
<queqiao-> ⟨§​κyℓαr ♀⟩ There are some things where MIT should be used but this is a case where I *really* wish they went for gpl.
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ The GoDot one from 2018 is GPL-3
<queqiao-> ⟨§​κyℓαr ♀⟩ Do they have a matrix or an irc? actually going to find the link one moment
<queqiao-> ⟨§​κyℓαr ♀⟩ lol, anything advanced enoufh to have any long term storage aboard xD
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ A toaster more powerful than the several first Macs
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ I invited you
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<queqiao-> ⟨l​amont⟩ that seems to be their most active repo
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ Yes
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ They still have the really old logo for it though
<queqiao-> ⟨l​amont⟩ can you give me an invite to their discord?
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ <https://discord.gg/Q3ZcrCeC>
<queqiao-> ⟨P​aculino (ŝi/ri/she/they)⟩ They still have the really old logo for it though; they switched to a rainbow background a long time ago (edited)
<queqiao-> ⟨B​utcher⟩ Not much progress by the looks.
<queqiao-> ⟨l​amont⟩ hmmm not sure they're going about that the right way
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<queqiao-> ⟨§​κyℓαr ♀⟩ ye, ignoring the technical aspects I am minimally familiar with and hardy looked at
<queqiao-> ⟨§​κyℓαr ♀⟩ actuallu brb
<queqiao-> ⟨§​κyℓαr ♀⟩ back
<queqiao-> ⟨§​κyℓαr ♀⟩ f*ck
<queqiao-> ⟨§​κyℓαr ♀⟩ I apparently was not joking about having the memory of the toaster lol
<queqiao-> ⟨§​κyℓαr ♀⟩ oh yeah
<queqiao-> ⟨B​utcher⟩ Howso?
<queqiao-> ⟨l​amont⟩ well looking at the code they seem to be focusing on part-interactions and it almost reads like they're building their own part-interaction physics engine first
<queqiao-> ⟨B​utcher⟩ Hmm that does not seem like the best plan.
<queqiao-> ⟨l​amont⟩ i skimmed it so i might have not gotten the right impression
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<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
<_whitenotifier> [Principia] pleroy labeled pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
<queqiao-> ⟨e​gg⟩ yeah I am not sure what the Intergrate (sic) Newton Dynamics in the readme is supposed to mean, but the code with the word physics in the name seems to be a great deal of glue surrounding a great deal of nothing (and abstractions that look like they are fundamentally tied to Euler integration, in the glorious tradition of game development)
<queqiao-> ⟨e​gg⟩ anyway, back to something slightly less removed from the topic: there was some discussion of stages, this is indeed something we have been largely avoiding. My understanding is MJ managed to get a decent approximation thereof and it’s a mess, and it’s not the kind of mess I would enjoy diving into.
<queqiao-> ⟨e​gg⟩ Maybe we could have some sort of Intermod Stage Specification thing like we have MFI so we can let another mod do the boring work and pick that up if available, but I don’t see that happening any time soon.
<queqiao-> ⟨e​gg⟩ Solids are a slightly different question, in that they are also a UX problem (you have fixed Δv, so you shouldn’t really have sliders for the Δv). Perhaps we could support « the solids that will light on staging, assuming nothing falls off » so that we have *some* support for solids.
<queqiao-> ⟨e​gg⟩ anyway, back to something slightly less removed from the topic: there was some discussion of stages, this is indeed something we have been largely avoiding. My understanding is MJ managed to get a decent approximation thereof and it’s a mess, and it’s not the kind of mess I would enjoy diving into.
<queqiao-> ⟨e​gg⟩ Maybe we could have some sort of Intermod Stage Specification thing like we have MFI so we can let another mod do the boring work and pick that up if available, but I don’t see that happening any time soon (cc @XKdiver: horrible ideas to give you more work).
<queqiao-> ⟨e​gg⟩ Solids are a slightly different question, in that they are also a UX problem (you have fixed Δv, so you shouldn’t really have sliders for the Δv). Perhaps we could support « the solids that will light on staging, assuming nothing falls off » so that we have *some* support for solids. (edited)
<queqiao-> ⟨l​pg⟩ That'd be nice. I get around the current behavior by patching solids to allow being Enabled but throttled to zero, just so the flight planner will acknowledge their existence
<queqiao-> ⟨l​pg⟩ It wouldn't be as much help with the "typical" rp-1 case of an unguided solid stage that's attached to its guidance unit right up until ignition time, but it'd still be an improvement
<queqiao-> ⟨l​pg⟩ (my own preference would be some sort of "advanced" UI where I can directly input the relevant parameters - initial mass, thrust & Isp, whatever is needed; but I realize that's not going to be popular)
<queqiao-> ⟨S​umguy⟩ but what about the thrust curve? thrust isn't constant
<queqiao-> ⟨e​gg⟩ yeah that is also an issue with the solids
<queqiao-> ⟨e​gg⟩ but in principle we could just fetch that
<queqiao-> ⟨e​gg⟩ it’s a cubic spline, nothing we can’t handle, and we actually integrate the thing, so we can just feed that into it
<queqiao-> ⟨e​gg⟩ oh hey look, an ancient issue https://github.com/mockingbirdnest/Principia/issues/870
<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj
<queqiao-> ⟨l​amont⟩ I wonder if what we need is a LibDeltaV
<queqiao-> ⟨l​amont⟩ its a mess AF problem
<_whitenotifier> [Principia] eggrobin synchronize pull request #2973: Documentation for a correctly-rounded cube root - https://git.io/J3BRj