UmbralRaptop changed the topic of #principia to: READ THE FAQ: http://goo.gl/gMZF9H; The current version is Fuchs. We currently target 1.5.1, 1.6.1, 1.7.x, 1.8.1, and 1.9.1. <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… | <egg> also 4e16 m * 2^-52 is uncomfortably large
<discord-> S​irius. — How I'm suppose to know when to launch a rocket to do a flyby of the Moon?
<discord-> S​irius. — I've tried with MechJeb but it didn't really worked...
<discord-> S​irius. — That's my big problem right now, so if anyone could help me, it will be very useful for me...
<discord-> S​ilavite. — @Sirius I'm actually attempting a lunar flyby right now. Where are you launching from?
<discord-> S​ilavite. — Canaveral?
<discord-> S​irius. — Yes
<discord-> S​ilavite. — That means you'll probably have to do an off-plane transfer.
<discord-> S​irius. — How I do that?
<discord-> S​ilavite. — That means the transfer is going to happen when the moon arrives at the ascending or descending node of your orbit.
<discord-> S​ilavite. — Well, you'll ARRIVE at that time
<discord-> S​irius. — And if I could an inclination to the Moon that will not cost me all my Delta V to reclinate me
<discord-> S​irius. — And if I could have an inclination to the Moon that will not cost me all my Delta V to reclinate me (edited)
<discord-> S​ilavite. — You could do a plane change, but plane changes in LEO are typically expensive
<discord-> S​irius. — Yes
<discord-> S​ilavite. — Are you doing RP-1 or just RO?
<discord-> S​irius. — RP-1 with RO
<discord-> S​irius. — And Principia of course
<discord-> S​ilavite. — OK
<discord-> S​irius. — So?
<discord-> S​ilavite. — So you'll want to launch when two conditions are met:
<discord-> S​ilavite. — - The time until the moon reaches its AN/DN with respect to the equator is equal to the length your transfer will take.
<discord-> S​ilavite. — - Your relative inclination with respect to the moon is minimized.
<discord-> S​ilavite. — My rule of thumb seems to be that the translunar coast takes about 4 days
<discord-> S​irius. — I see my relative inclination with MechJeb right?
<discord-> S​ilavite. — Yes
<discord-> S​ilavite. — You'll select the moon as a target and use the rendezvous planner to view relative inclination
<discord-> S​irius. — Wdym by "length your transfer will take" ?
<discord-> S​ilavite. — You your spacecraft and the moon to be in the same place at the same time. Without changing inclination, that can only happen at the AN or DN. Thus, if your translunar coast takes X number of days, you want the moon to also take X number of days to reach it's AN or DN (whichever you're aiming for).
<discord-> S​ilavite. — You want your spacecraft and the moon to be in the same place at the same time. Without changing inclination, that can only happen at the AN or DN. Thus, if your translunar coast takes X number of days, you want the moon to also take X number of days to reach it's AN or DN (whichever you're aiming for). (edited)
<discord-> S​ilavite. — You want your spacecraft and the moon to be in the same place at the same time. Without changing inclination, that can only happen at the AN or DN. Thus, if your translunar coast takes X number of days, you want the moon to also take X number of days to reach its AN or DN (whichever you're aiming for). (edited)
<discord-> S​irius. — Ooh
<discord-> S​irius. — How I see when the Moon gonna reach her AN or DN?
<discord-> S​ilavite. — If I'm gonna be honest, I don't know. If there are tools in Mechjeb or Principia which help you locate the AN or DN of a celestial, I haven't found them. I usually just end up eyeballing it.
<discord-> S​ilavite. — You can make a decent guess with the knowledge that the moon's orbital period is 27 days, and that its roughly circular.
<discord-> S​irius. — Yeah
<discord-> S​ilavite. — So ~60 degrees of lead is what I try to go for
<discord-> S​irius. — An orbit of 60 degrees?
<discord-> S​ilavite. — Let the moon be 60 degrees ahead of its AN/DN with respect to the equator
<discord-> S​ilavite. — By ahead, I mean before
<discord-> S​ilavite. — That was worded kinda poorly
<discord-> S​irius. — Ok
<discord-> S​irius. — Thanks
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<discord-> R​urouniDonut. — i sorta just eyeball at this point on Moon launches
<discord-> R​urouniDonut. — Sometimes launching at the capes inclination wont work, might have to launch to a different inc
<discord-> R​urouniDonut. — Getting to the moon is really easy for me now, I can do it whenever
<discord-> S​irius. — Yeah
<discord-> R​urouniDonut. — Doesnt have to be anything crazy
<discord-> R​urouniDonut. — Sometimes just going to 30 degree inc makes it so I can just burn prograde to the Moon
<discord-> S​irius. — But I'm on an early career and I'm beginner to Principia
<discord-> R​urouniDonut. — Sim A LOT
<discord-> R​urouniDonut. — I always sim my launches for the trajectory
<discord-> S​irius. — Thanks for the tip 👍
<discord-> R​urouniDonut. — yep
<discord-> R​urouniDonut. — and if you dont have flight planning
<discord-> R​urouniDonut. — find the launch azimuth that will let you just burn prograde to the moon
<discord-> S​irius. — @Silavite So I should launch now? The date is 1959-12-04
<discord-> S​irius. — Calendar of 1959:
<discord-> S​irius. — And I should do the maneuver at the AN or DN
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<discord-> S​ilavite. — It's a little difficult to tell from that photo. Could you get a screenshot from the inertial frame?
<discord-> S​irius. — Sorry that I didn't respond to you, but here's what the maneuver looks like
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<discord-> S​irius. — So yeah, I presume it worked, just have to manage to maneuver to use all my Delta V
<discord-> S​irius. — So yeah, I presume it worked, just have to manage the maneuver to use all my Delta V (edited)
<discord-> S​irius. — Thanks @Silavite
<discord-> S​irius. — I just hope that the SRB will not do any trouble
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<discord-> g​ravShark. — Is it possible when launching from Brownsville to use MJ's launch to plane function for Lunar Missions? I've tried, but it doesn't seem to actually engage autopilot functions and throttle/stage/etc. I just use Launch To Plane to count down to the window and launch due east, which of course isn't accurate to 0% rel inc
<discord-> g​ravShark. — I can surely guess a few reasons why but wondering if anyone else can let me know 🙂
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<discord-> l​pg. — start by grabbing the latest MJ-dev build, which has fixes related to launch-into-plane
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<discord-> g​ravShark. — Nice, thank you 🙂 testing it now
<discord-> S​irius. — Almost!!
<discord-> S​irius. — (With SRB stages, Baby Sergeant)
<discord-> S​irius. — Yes finally!!!
<discord-> S​irius. — First time that I've succeed to do a Moon flyby under 5000KM 😄
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<discord-> S​irius. — ❤️
<discord-> S​irius. — 👍 (edited)
<discord-> S​irius. — Thank you very much @Silavite
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<discord-> _​felixu_. — How come Transfer Window Planner gives vastly different times based on whether or not you're going to circularise, and which one is to be used with Principia (flyby/no flyby)?
<discord-> e​gg. — I do not understand what you mean
<discord-> e​gg. — which times?
<discord-> D​amien. — @_felixu_ if you're going to capture you might want a slower transit to minimise relative velocity when you get there. If you're just doing a flyby you can yeet it as fast as you like
<discord-> _​felixu_. — And both are fine with Principia?
<discord-> D​amien. — not sure tbh
<discord-> D​amien. — not used TWP for a while
<discord-> e​gg. — what does "fine with Principia" mean?
<discord-> e​gg. — I do not understand your questions
<discord-> _​felixu_. — > I do not understand what you mean
<discord-> _​felixu_. — @egg In Transfer Window Planner, you can tick a circle saying **No Flyby?** iirc, which will change the transfer window date
<discord-> D​amien. — it shouldn't make a difference how you do the transfer, in principia or not
<discord-> e​gg. — ah, TWP is a tool
<discord-> D​amien. — just bear in mind that TWP is an approximation, and more so with principia
<discord-> _​felixu_. — > what does "fine with Principia" mean?
<discord-> _​felixu_. — @egg That what TWP says is a good transfer window is still a good transfer window with Principia installed
<discord-> D​amien. — also it assumes that all bodies are coplanar
<discord-> D​amien. — (might be wrong about that but I recall that being a thing)
<discord-> e​gg. — (I did not know about TWP so I was very confused)
<discord-> D​amien. — <https://forum.kerbalspaceprogram.com/index.php?/topic/84005-17x-transfer-window-planner-v1710-august-19/>
<discord-> _​felixu_. — Oh, haha. What do you use?
<discord-> D​amien. — @_felixu_ TWP is for people who actually play KSP 😛
<discord-> D​amien. — egg is so galaxybrained he gets his kicks by making a mod for a game he doesn't actually want to play
<discord-> e​gg. — the few times when I have planned a transfer I have done it by hand by trial and error starting from educated guesses from a paper
<discord-> D​amien. — he's like an automotive engineer who doesn't like to drive cars 🙂
<discord-> e​gg. — (for Earth-Moon that is)
<discord-> e​gg. — Mun is easy to do by eye
<discord-> D​RVeyl. — Interesting way to describe it, but the question is, did egg ever play KSP before being involved with Principia. 🙂
<discord-> D​amien. — no
<discord-> D​amien. — which explains a lot
<discord-> e​gg. — I did play some KSP !
<discord-> D​amien. — androids don't play games
<discord-> D​amien. — stop lying
<discord-> D​RVeyl. — (A lot of folks make a transition from playing a game, to developing for it. It's a way to keep involved with something that you liked but have staretd to enjoy less just from playing.)
<discord-> _​felixu_. — @egg Why do you need to calculate transfer window for the moon? I just launch into the correct inclination and then plot a node at roughly the right time, and fine tune
<discord-> e​gg. — but it has been a while since I have played it in a continued fashion, as opposed to an occasional launch or plane flight to see what RSS looks like these days
<discord-> D​RVeyl. — (A lot of folks make a transition from playing a game, to developing for it. It's a way to keep involved with something that you liked but have started to enjoy less just from playing.) (edited)
<discord-> e​gg. — @_felixu_ yeah no need for windows for simple transfers; if you want to do an outer transfer with the help of the Sun things get trickier
<discord-> e​gg. — never played career for instance, because it did not exist when I played regularly. I did do a fairly long science mode game though
<discord-> D​amien. — I don't actually know how to plan that
<discord-> D​amien. — I eyeball my outer transfers
<discord-> _​felixu_. — Speaking of, do you guys do more gravity assists with Principia?
<discord-> D​amien. — chronic career restart syndrome means no unfortunately
<discord-> D​amien. — I have played with it though in my principia experimenting install
<discord-> _​felixu_. — And is it easier than patched conics?
<discord-> D​amien. — I never did any GAs in stock so I'm not the right person to ask
<discord-> D​amien. — is the principia UI easy to use for it though? oh hell no
<discord-> D​RVeyl. — The better control over the viewing frames probably can help a lot with gravity assist planning, tho. Versus finagling trying to even find the close approach?
<discord-> D​amien. — it's probably really effective once you learn it, but it's not very intuitive
<discord-> D​amien. — some of the things you'd do in stock (see the trajectory in both SCI and B(ody)CI at the same time and use the body's orbit line as a reference for pointing your exit trajectory) don't work so it's learning it all from scratch in an unfamiliar system
<discord-> D​amien. — a solid tutorial for gravity assists in principia would be really helpful
<discord-> e​gg. — if someone has experience with doing these, I would be interested in reading about it as well (in particular to see what kind of aids we could add)
<discord-> e​gg. — I suspect something based on the analyser to advance ejections by a synodic period might be of use
<discord-> D​amien. — Reach would be the man to ask as he's godlike at it but he's not around much
<discord-> D​amien. — then again he probably doesn't need any aids anyway
<discord-> _​felixu_. — I suppose we could always go by the dates of real gravity assists and know that with Principia we can take advantage of the same assists in RO or RP-1
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<discord-> D​amien. — yeah that's the cheaty option
<discord-> D​amien. — in my limited experimentation with it, what I struggled with is trying to use it in a stockish way. You know what your SCI orbit should look like before and after the encounter, so after you get the encounter you use BCI to fine tune your ejection direction so you eject body prograde to get a boost to your sun orbit and body retro to slow down. All fairly straight forward. The issue I had was that
<discord-> D​amien. —
<discord-> D​amien. — In stock, if the body was at 9 o'clock relative to the camera and passing top to bottom, I could rotate the camera so it was at the bottom and left to right, and aim my exit trajectory to the right to get a prograde boost
<discord-> S​ir Mortimer. — I use KAC for transfer windows, plan for some extra fuel and start burning from a 100km orbit. Works like a charm 🙂
<discord-> S​ir Mortimer. — Fine tuning the orbit: focus on your target body, set the reference frame to that body and look at the Pe marker.
<discord-> S​ir Mortimer. — Fine tuning the transfer: focus on your target body, set the reference frame to that body and look at the Pe marker. (edited)
<discord-> D​amien. — with principia, it's drawn with reference to where it is now, so if I plan a maneuver when the body is at 12 o'clock but intercept is at 9, I can't eject in the body's orbital direction as it now because after a 90° rotation in its orbit that will be 90° out and no longer the right direction
<discord-> D​amien. — clearly trying to use stock tricks with principia doesn't work
<discord-> D​amien. — but there's no solid guides on what system you really should use
<discord-> S​ir Mortimer. — (I hope my duna rover will survive reentry and touchdown, I never tested it
<discord-> S​ir Mortimer. — (I hope my duna rover will survive reentry and touchdown, I never tested it) (edited)
<discord-> S​ir Mortimer. — (I don't even know if it *drives* well, maybe should have taken it for a test drive before strapping it onto a rocket)
<discord-> S​ir Mortimer. — BTW got my iMac back today. 32GB of ram instead of 8GB. It's quite a difference.
<discord-> S​ir Mortimer. — Funny thing is, now that it's got more ram, it seems to need *less* of it
<discord-> S​ir Mortimer. — (also, principia keeps yelling at me to use the latest version)
<discord-> D​amien. — you should. it has important fixes to craft rotation
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<discord-> e​gg. — > trying to use it in a stockish way
<discord-> e​gg. — yeah we don’t really want to optimize for that
<discord-> e​gg. — but on the other hand it would be nice if we helped to use it in a Principiaish way
<discord-> e​gg. — (and if there were guides)
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<discord-> D​amien. — I agree
<discord-> D​amien. — it's an education problem, not a system problem imo
<discord-> D​amien. — although if aids are possible then fantastic
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<discord-> S​ir Mortimer. — @Damien so does my version, at least partially. It's an intermediate build pulled from the build system
<discord-> S​ir Mortimer. — (needed it for KC tests)
<discord-> D​amien. — ah, fair enough then
<discord-> e​gg. — you can use the latest version though, it has the API
<discord-> e​gg. — you can use the latest release though, it has the API (edited)
<discord-> S​ir Mortimer. — will download tonight
<discord-> S​ir Mortimer. — so, to stop a big ship from tumbling in entertaining ways while time warping to duna, what would be the best approach? spin stabilization? How fast is fast enough?
<discord-> e​gg. — doesn’t need to be very fast I think
<discord-> e​gg. — significantly faster than the tumble residual you get from your nearly-nonrotating state
<discord-> S​ir Mortimer. — think of a crewed vessel, basically the form of a big cigar with some greeble on it.
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<discord-> S​ir Mortimer. — well, I'll see.
<discord-> S​ir Mortimer. — hm
<discord-> S​ir Mortimer. — gravity rings... is there a way to let principia know that a gravity ring has a stablizing effect?
<discord-> e​gg. — no, Principia assumes the vessel is rigid when warping
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<discord-> e​gg. — try to just tap q once and warp tbh
<discord-> e​gg. — that should be much more rotation than what you get from SAS residuals
<discord-> S​ir Mortimer. — ok. so my kerbals won't be vomiting all the way to duna then.
<discord-> S​ir Mortimer. — 0.5 rpm or something like that
<discord-> S​ir Mortimer. — i'll see when I get there.
<discord-> e​gg. — (well, if you want to spin them at 100 rpm just to be sure that is also an option)
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<discord-> d​awidePl. — I'm not mad
<discord-> e​gg. — You must be, or you wouldn’t have come here.
<discord-> d​awidePl. — I just check this channel
<discord-> d​awidePl. — lmao
<discord-> d​awidePl. — Principia seems too hard for me to install
<discord-> d​awidePl. — All these unstable orbits
<discord-> h​ashbrown565. — Welcome to the Universe
<discord-> d​awidePl. — Yus
<discord-> D​amien. — >hard to install
<discord-> D​amien. — *unzip, copy, paste*
<discord-> D​amien. — come join us
<discord-> D​amien. — we have squigly lines
<discord-> D​amien. — we have squiggly lines (edited)
<discord-> h​ashbrown565. — Not gonna lie I understand where he's coming from. I use CKAN specifically because I don't trust myself enough to not screw up, so the idea of manual installs makes me nervous.
<discord-> e​gg. — to be honest we tend to be vocal about incorrect installs
<discord-> e​gg. — if you are lucky we will just show yell at you from a modal dialog that refuses to go away
<discord-> e​gg. — otherwise we will just crash on load
<discord-> e​gg. — either way, can’t miss it
<nomalraptop> sudo apt-get install principia
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<discord-> S​ilavite. — Are there any plans to add gravity-gradient torque? (Or, while this isn't really the purview of Principia, radiation pressure?)
<discord-> e​gg. — not at the moment
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<Rkunze> Hello everybody.
<egg|laptop|egg> hello
<Rkunze> Do you have any tips for compiling principia with clang 10?
<Rkunze> I'm trying to track down a crash that I suspect is caused by a mismatch of the official binaries and my libc++.
<Rkunze> But since I'm on Arch Linux here, I don't have clang/libc++ 8 around anymore.
<egg|laptop|egg> no idea; we compile with clang 8 at the moment
* raptop could imagine gravity-gradient torque showing up if gravity was applied per-part (performance, what's that?)
<Rkunze> I'll try on my own, then. I found (and fixed) one minor glitch in the make file so far (Clang 9+ doesn't need linking to libc++fs anymore), but right now I'm stumped on a linker error about duplicate symbols in "make test"...
<egg|laptop|egg> no but also doing things per-part requires modelling part interactions, which is a mess and also is sure to introduce horrible instabilities
<egg|laptop|egg> you could however compute torques and integrate them symplectically in alternation with the resolution of Arnold’s equation
<raptop> hrm
<discord-> h​ashbrown565. — does TRAPPIST-1 for Principia replace the solar system entirely or is it an addition to the solar system?
<discord-> A​cer_Saccharum. — total replacement
<discord-> h​ashbrown565. — Damn, okay. Are there any mods that add another solar system, or is that not really a thing for Principia?
<discord-> _​felixu_. — Real Exoplanets is for you, my friend.
<discord-> _​felixu_. — https://forum.kerbalspaceprogram.com/index.php?/topic/187033-181-real-exoplanets-v096-04032020/ @hashbrown565
<discord-> e​gg. — that is not really a thing though, because you cannot get there
<discord-> h​ashbrown565. — I was looking at that mod too, but I wasn't sure if it was compatible with Principia
<discord-> e​gg. — there is no hard incompatibility with adding more solar systems, it is simply that you will never get there
<discord-> h​ashbrown565. — Do you mean it's not possible in game to get there or it's just not there AT ALL?
<discord-> e​gg. — it is there
<discord-> e​gg. — you just cannot get there, because you cannot warp fast enough
<discord-> _​felixu_. — You'll never go through the effort of using engines to get there
<discord-> e​gg. — see the (rather poorly named) issue https://github.com/mockingbirdnest/Principia/issues/1737
<discord-> h​ashbrown565. — Okay, because I also plan on installing Near Future
<discord-> A​cer_Saccharum. — that won't get you going fast enough
<discord-> _​felixu_. — The dV required is massive. I would just install one of the teleportation/warp drive mods
<discord-> h​ashbrown565. — Damn you Sun and your incredibly high escape velocity!
<discord-> e​gg. — teleportation/warp drive mods *are* incompatible with Principia
<discord-> _​felixu_. — Ah, shite
<discord-> _​felixu_. — So, @hashbrown565 , if you want purdy planets to stare at in the tracking station, get Real Exoplanets 🙂
<discord-> h​ashbrown565. — Challenge.......accepted
<discord-> e​gg. — (might hurt performance a bit, though)
<discord-> h​ashbrown565. — Screw it I'm gonna try getting there anyways
<discord-> h​ashbrown565. — Thanks my dudes
<discord-> A​cer_Saccharum. — the sun's escape velocity is a tiny fraction of the speed you want to go interstellar
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<discord-> A​cer_Saccharum. — 4 light years is 38 trillion km
<discord-> h​ashbrown565. — Then there will be many Kerbal deaths
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<raptop> Useful speeds for interstellar travel are at least a few % c. Well, in realistic scales
<raptop> There's a case to be made for a Kerbalish scale, were the nearest star is only like 1e12 m away
<raptop> er, 1e15?
<discord-> A​cer_Saccharum. — the highest speed you can really reach with any engine from near future propulsion is ~300 km/s
<discord-> A​cer_Saccharum. — that means it will take you **four thousand years** to reach proxima centauri
<discord-> e​gg. — now, mind you, on a good computer you might be able to do 1e6 warp
<discord-> A​cer_Saccharum. — and that's with no ability to slow down
<discord-> e​gg. — so I guess if you stare at it for a couple of days at max timewarp you might get there?
<discord-> A​cer_Saccharum. — imagine how large any geosynchronous satellite's history would be
<discord-> e​gg. — oh yeah, don’t have other satellites
<discord-> A​cer_Saccharum. — or asteroids, or debris
<discord-> e​gg. — indeed
<discord-> e​gg. — I mean, in 4000 years the other satellites would all be obsolete anyway
<discord-> h​ashbrown565. — 4000 years is nothing compared to the *interstellar glory of Kerbalkind*
<discord-> e​gg. — clearly you should have a custom start of the game 4000 years ago, so it arrives in the present day
<discord-> A​cer_Saccharum. — you're going to want far future technologies if you want to even think about interstellar flight
<discord-> e​gg. — and attach to your probe a golden tablet with a greeting in Akkadian to spacefaring civilizations
<discord-> A​cer_Saccharum. — not compatible with RO though
<raptop> RO needs better unicode support, then
<discord-> h​ashbrown565. — Imagine I miss
<discord-> 𒀯​ 𒄷 𒄈𒀭𒁇. — Or, rather, from this account, RO needs better unicode support them
<discord-> e​gg. — hehe
<discord-> h​ashbrown565. — like, what, years of burning and I end up missing Alpha Centauri's gravity well
<discord-> h​ashbrown565. — *bye*
<discord-> A​cer_Saccharum. — you'll need to slow down at the other end too
<raptop> Stellar velocities are only a few hundred km/s, so you can plan ahead/do corrections during the burn
<raptop> And mid-course corrections if you feel like it. etc etc
<discord-> e​gg. — (also you will need to provide a cartesian initial state for the other systems if you use them in conjunction with RSS)
<discord-> h​ashbrown565. — I didn't even think about how I'd slow down from an interstellar burn lol
<raptop> Conside: deploying a giant sail at the end of the flight, and using the target star's photons
<raptop> (What do you mean you wanted to go to Prox Cen, and not Sirius A?)
<discord-> A​cer_Saccharum. — can a solar sail ever hope to bleed off hundreds of km/s?
<discord-> h​ashbrown565. — Would a binary star system mean double the photons?
<raptop> IIRC, yes. Depends on details, etc
<raptop> Eh, stellar luminosity varies much more
<raptop> eg: Sirius A is ~25 $L_\odot$
<discord-> h​ashbrown565. — Why would I wanna go to Sirius A?
<raptop> And Proxima centauri is like 1e-4
* discord- e​gg. — gives raptop a ☉_
* raptop emits broken LaTeX
<discord-> e​gg. — waiting for G_\odot
* raptop groans
<discord-> h​ashbrown565. — Ohhhh I see what I did, I mistakenly thought the Alpha Centauri system was a binary star system, not triple
<discord-> A​cer_Saccharum. — I swear @ egg
<raptop> Eh. Alpha Cen A is like 1.2x L_☉, and B like 0.5?
<discord-> A​cer_Saccharum. — I swear
<discord-> A​cer_Saccharum. — @ egg (edited)
<raptop> But they're also a fair number of au apart
<discord-> A​cer_Saccharum. — I swear
<discord-> A​cer_Saccharum. — @ egg
<discord-> A​cer_Saccharum. — forgot the _ (edited)
<discord-> S​tandecco. — just noticed that ☉ is both the sun mass symbol and the facing out vector
<discord-> e​gg. — in Unicode those things are disunified
<raptop> If the latter is in unicode, I think it has a different code point
<discord-> e​gg. — Sun is ☉, whereas circled dot operator is ⊙
<raptop> However, there is unification between some gender and alchemical symbols IIRC
<discord-> e​gg. — yes
<discord-> e​gg. — and astronomical & alchemical
<discord-> h​ashbrown565. — I know exactly none of what you guys are talking about and yet I wanna go interstellar. ooohhhhhh boy
<discord-> S​tandecco. — > ☉ ⊙
<discord-> S​tandecco. — ah, totally different
<discord-> e​gg. — 🜨 is Earth and Verdigris, whereas ⊕ is a direct sum and ⨁ is an n-ary direct sum
<discord-> h​ashbrown565. — *what*
<discord-> S​tandecco. — they're just symbols
<discord-> h​ashbrown565. — *oh*
<raptop> hashbrown565: As far as interstellar flight goes, this is a classic and sadly not as out of date as it should be for being 31 years old https://www.amazon.com/Starflight-Handbook-Pioneers-Interstellar-Travel/dp/0471619124/
<discord-> h​ashbrown565. — KSP: if you wanna be good, *read a book*
<raptop> I mean, we recommend Fundamentals of Astrodynamics for a reason
<discord-> D​amien. — @hashbrown565 welcome to #principia where nothing makes sense and you understand nothing but it's still cool
<discord-> S​tandecco. — ⊕ is also the symbol for floating point sum
<raptop> aaaa, floats
<discord-> S​tandecco. — at least, it was in the notation we used
<discord-> h​ashbrown565. — How long did it take you to learn astrophysics? *about 1000 dead kerbals*
<raptop> <_< >_>
<discord-> h​ashbrown565. — Other people: How long did it take you to learn astrophysics? Me: *about 1000 dead kerbals* (edited)
* Rkunze thinks I may have tracked down the cause of my linker error with clang 10.
<Rkunze> what I get from "make test" is this error:
<Rkunze> /usr/bin/ld: obj/tools/generate_kopernicus.o:(.rodata+0x8): multiple definition of `principia::quantities::si::Unit<double>'; obj/tools/generate_configuration.o:(.rodata+0x8): first defined here
<Rkunze> /usr/bin/ld: obj/tools/generate_kopernicus.o:(.rodata+0x0): multiple definition of `principia::base::internal_traits::all_different_v<>'; obj/tools/generate_configuration.o:(.rodata+0x0): first defined here
<Rkunze> this looks similar to the error described here: https://github.com/boostorg/hana/issues/446
<Rkunze> and this is has been caused by a change in clang 9 as to how to treat constexpr for linking, apparently.
<Rkunze> I think declaring the relevant definitions as inline should fix it.
<discord-> e​gg. — moar specifiers
<Rkunze> But: I'm by no means a C++ expert, and looked at the principia codebase for the first time yesterday.
<Rkunze> So: Question to the experts: Are these supposed to be inlined?
<discord-> e​gg. — The reserved word `inline` has essentially nothing to do with inlining
<discord-> e​gg. — it has to do with linkage though
<discord-> e​gg. — on the other hand I am somewhat surprised that template variables would not be inline
<discord-> e​gg. — ah, this is an explicit specialization, so it is not templatized
<Rkunze> Think this may be well into the real of c++ esoterica
<discord-> e​gg. — Rkunze no but this is not the question; constexpr does not imply inline for a variable
* Rkunze rememebers why he usually sticks with Golang, Rust or even Java...
<discord-> e​gg. — but templatization does; but this is specialized so it no longer depends on any template parameters
<discord-> e​gg. — so indeed `Unit<double>` or `all_different_v<>` probably need an inline
<Rkunze> OK, I'll try it an see if it compiles.
<Rkunze> Do you want a pull request for it if it does?
<discord-> e​gg. — sure, that seems to be a bug in our code and not a bug in the compiler, so we should fix it even if we are still using compilers that accept it
<discord-> B​utcher. — Woah, you have bugs?
<discord-> e​gg. — inconceivable
<discord-> h​ashbrown565. — I think you mean *unacceptable*
<Rkunze> Did not workfor me - changing it to
<Rkunze> inline template<>
<Rkunze> constexpr bool all_different_v<> = true;
<Rkunze> results in
<Rkunze> ./base/traits.hpp:12:1: warning: ignoring 'inline' keyword on explicit template instantiation [-Wstatic-inline-explicit-instantiation]
<discord-> e​gg. — hmmm
<discord-> e​gg. — That is not the syntax I would have used, I am surprised it compiles
<discord-> e​gg. — template<> constexpr inline blah blah blah
<discord-> e​gg. — not sure what a leading inline does
<Rkunze> ok, I'll try that.
<discord-> e​gg. — (or inline constexpr, whatever; but before the template seems weird)
<Rkunze> As I said - I'm anything but a c++ experts...
<Rkunze> "inline constexpr" seems to work...
<discord-> B​utcher. — > I think you mean *unacceptable*
<discord-> B​utcher. — @hashbrown565 Principia is acceptable.
<discord-> h​ashbrown565. — High praise coming from a lemon
<discord-> h​ashbrown565. — Ah man
<discord-> h​ashbrown565. — You know you've messed up when the dude who literally co-wrote the code implementing n-body physics into KSP sends a meme your way
Jesin has quit [Quit: Leaving]
Jesin has joined #principia
<Rkunze> OK, compile went through with the two additional "inline"s. I get one failure from "make test" (for OrbitalElementsTest.KeplerOrbit) and 34 disabled tests (on master). Is this expected?
<discord-> S​ir Mortimer. — landing a rover on duna with principia: done.
<discord-> e​gg. — congratulations!
<discord-> S​ir Mortimer. — lost a bunch of orbiters on the way there (launched them without principia, turns out the orbits weren't all that stable)
<discord-> e​gg. — @𒀯 𒄷 𒄈𒀭𒁇 @Sir Mortimer also, I summarized my current thoughts on the optical stuff https://github.com/Kerbalism/KerbalismContracts/wiki/Design#game-mechanics-for-optical-imagers
<egg|laptop|egg> cc raptop
<discord-> e​gg. — (raptop is @𒀯 𒄷 𒄈𒀭𒁇, as the name indicates)
<egg|laptop|egg> raptop: thoughts on the Lyot stuff?
<discord-> h​ashbrown565. — Yeah so I tried running Real Exoplanets with Principia and it caused the game to hard crash whenever I tried to go past the menu screen. I checked the Principia log files and it was basically saying that the gravity model for Trappist-1 was just not there. There go my dreams of going interstellar
<discord-> e​gg. — yes, as I said you need an initial state configuration
<discord-> h​ashbrown565. — Haha now I see what you were saying.
<discord-> h​ashbrown565. — Thanks!
<raptop> egg|laptop|egg: Lyot and Vortex coronagraphs are magic. I'd say dark magic, but they involve light, so...
<raptop> Having a model of OWA and IWA seems a bit difficult, given that pointing is largely fake, but maybe?
<discord-> e​gg. — OWA? IWA?
<discord-> B​utcher. — Darklight magic.
<discord-> e​gg. — no that is multiplayer
<raptop> Outer Working Angle and Inner Working Angle
<raptop> I mean, granted, if we could effectively model coronagraphs, it would be tempting to have a starshade...
<discord-> h​ashbrown565. — @Transparent_Elemental Okay, that makes a lot of sense. For example, if I wanted to go to the moon I'd only be looking at frames of reference for Earth, correct?
<raptop> Dealing with KSP's craft focus and unloaded craft issues when they need to be ~1e7 to 4e7 m apart is an exercise for the reader
<discord-> T​ransparent_Elemental. — Egg knows better
<discord-> e​gg. — Re. Lyot, can it make sense to have IWA/OWA fixed (to reduce the number of tweakables), and sufficiently small (you will waste some aperture watching dark things when IWA is set to something low, but given that these are small apertures this does not seem to be the end of the world)
<discord-> e​gg. — or should they really be independent
<discord-> e​gg. — (note: this is for solar coronagraphs; the stuff on HST doesn’t affect orbit design)
<raptop> Depending on design, OWA tends to be some multiple of IWA
<raptop> IIRC
<discord-> T​ransparent_Elemental. — @hashbrown565 there's a tutorial for the stock system on how to reach the Mun, but it's basically the same as RSS, the only exception being the Moon's tilt which changes as years go by in 11 year cycle https://github.com/mockingbirdnest/Principia/wiki/A-guide-to-going-to-the-Mun-with-Principia
<discord-> h​ashbrown565. — Thanks!
<discord-> e​gg. — yeah, but that multiple varies a little bit
<discord-> e​gg. — see Cor-1 and Cor-2 on SECCHI on STEREO
<raptop> I recall something with wavelength being a factor (I think range vs throughput because of surpressing diffraction), but I'm not sure how important that is with sun-staring instruments
<raptop> Certainly it matters for HabEx, WFIRST, or GPI
<discord-> e​gg. — right, but there everything is tiny
<discord-> e​gg. — and coronagraphy does not affect the orbit meaningfully in those cases
<discord-> e​gg. — (especially for GPI !)
<discord-> e​gg. — whereas for STEREO, fixed IWA means variable occlusion size as measured in solar radii
<discord-> e​gg. — so it means that something with a Lyot coronagraph can’t just fool around on elliptic orbits
<raptop> Ah!
<discord-> e​gg. — or rather, if it does, its perihelion is limited (IWA must not be smaller than the sun), and higher aphelia means imaging higher layers of the corona
<discord-> e​gg. — you could probably do some silliness by putting a probe with a single Lyot coronagraph on an elliptic orbit, where the coronagraph plays the role of Cor-2 at aphelion and Cor-1 at perihelion :-p
<raptop> pfft
<discord-> e​gg. — I guess the question is whether it is hard/messy to have a variable IWA (in which case those concerns are real and interesting for orbit design) or whether it is trivial (in which case none of this exists)
<raptop> My (limited) understanding is that there are slow advancements in what can be done with IWA and OWA with time (so a 2000 coronograph would be better than a 1980 one which would be better than a 1960 one...)
<raptop> Uh, I'd have to do some digging on the formulae involved for IWA on OWA, but they might not apply for something half a degree across
<raptop> Like, that's pretty big
* raptop keeps on thinking of that one SOHO camera where you can see the arm of the disk that blocks the sun
<mofh> yeah isn't that just the SOHO coronagraph?
<discord-> e​gg. — oh I should add the SOHO instruments to the survey
<discord-> e​gg. — > Solar Ultraviolet Measurement of Emitted Radiation (SUMER)
<discord-> e​gg. — > and attach to your probe a golden tablet with a greeting in Akkadian to spacefaring civilizations
<discord-> e​gg. — > 𒅗𒆷𒉆𒇽𒍇𒇻𒉌𒉡𒅗𒄭𒊩𒉌𒅋𒇷𒄰
<raptop> :D
<discord-> e​gg. — Are multilayer coated mirrors for EUV usable in NUV or visible at all, or should we count SOHO EIT and STEREO SECCHI EUVI in the same category as X-ray telescope, just with fancier tech inside which doesn’t really matter to mission design
<discord-> e​gg. — Are multilayer coated mirrors for EUV usable in NUV or visible at all, or should we count SOHO EIT and STEREO SECCHI EUVI in the same category as X-ray telescopes, just with fancier tech inside which doesn’t really matter to mission design (edited)
<mofh> EUV is a nightmare
<discord-> e​gg. — (and ALEXIS)
<mofh> lile it's worse to deal with than *either* NUV or Xray b/c it's absorbed by like fucking everything
<raptop> Sounds right. Not sure if you can do grazing mirrors with FUV
<discord-> e​gg. — yes, WFC on ROSAT
<discord-> e​gg. — same wavelengths as ALEXIS
<discord-> e​gg. — vs. 66 eV to 93 eV on ALEXIS
<_whitenotifier-d13c> [Principia] rkunze forked the repository - https://git.io/Jfwpj
<_whitenotifier-d13c> [Principia] rkunze opened pull request #2592: Fix linker error when compiling with clang 9+ - https://git.io/Jfwh8
<Rkunze> Just sent the pull request for the clang 9+ linker error fix.
<Rkunze> Sadly, recompiling Principia did not fix my crash issue. Guess I'll got for a parallel Ubuntu install as gameloader next...