raptop changed the topic of #principia to: READ THE FAQ: http://goo.gl/gMZF9H; The current version is Gateaux. We currently target 1.8.1, 1.9.1, and 1.10.1. <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
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[Principia] pleroy labeled pull request #2799: Interrupt the orbit analysis if the mission duration changes - https://git.io/Jkdu9
<discord->
Butcher. — I'll have to get Principia building again.
<discord->
egg. — I think you mean flight plan, not prediction
<discord->
Butcher. — I do
<discord->
Butcher. — For targeted landings.
<discord->
egg. — aah
<discord->
egg. — you are going to run into trouble though, because of topography
<discord->
egg. — the moon is really far from its 0 altitude in RSS
<discord->
egg. — for landings I would really want to:
<discord->
egg. — 1. intersect with the topography;
<discord->
egg. — 2. show the predicted impact point.
<discord->
egg. — 1. could probably be done by drawing the last segment in 3d (we used to draw the whole trajectory in 3d, but that is horrendously expensive)
<discord->
egg. — alternatively maybe the best way is to interrogate the game about the altitudes of the below-max-topography segments at regular intervals
<discord->
Zeusbeer. — Or via a hotkey ingame that opens a menu, I think EVE has something like that
<discord->
Zeusbeer. — Changeable things that can only be done via changing config files are sad
<discord->
egg. — who’s going to maintain the hotkey handling code and the menu drawing code
<discord->
Zeusbeer. — I don't know how that works :)
<discord->
egg. — the point is that keeping features working has a cost ; this is not something that people will use a lot (I expect it to be done less often than, say, adding a J2 to Kerbin, and nobody is suggesting an Kopernicus GUI), so maintaining a UI for that is not going to happen
<discord->
Zeusbeer. — Alright, it was just my suggestion
<discord->
Zeusbeer. — ⛈️ 🥚
<discord->
egg. — the point is that keeping features working has a cost ; this is not something that people will use a lot (I expect it to be done less often than, say, adding a J2 to Kerbin, and nobody is suggesting a Kopernicus GUI), so maintaining a UI for that is not going to happen (edited)
<discord->
egg. — KSP config files, for all their ills, are pretty accessible, reasonably robust (and so low-maintenance for the mod), and with MM you have a great deal of flexibility; using that for little-used customization features (e.g. RSSDateTimeFormatter format choice) or complex customizability that you may want to compose with other things via MM (Kopernicus configuration, Principia & RSSDateTimeFormatter epoc
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[Principia] eggrobin synchronize pull request #2799: Interrupt the orbit analysis if the mission duration changes - https://git.io/Jkdu9
<discord->
Butcher. — I was not planning to write a new pop up gui anyway. 😆
<discord->
Butcher. — Also I can cope with the topography issues if I can get a reasonable estimate of where the orbit crosses area level.
<discord->
egg. — yeah, I guess that can be a stopgap. I wonder how to properly address the issue longer-term though
<discord->
Butcher. — For actually hitting a waypoint landings I do correction during descent anyway, so the requirement is being close enough for that.
<discord->
Butcher. — Perhaps only do 3d plotting below the safe altitude?
<discord->
Butcher. — Although in a low but not impacting orbit that could get expensive.
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[Principia] eggrobin commented on pull request #2799: Interrupt the orbit analysis if the mission duration changes - https://git.io/Jkbru
<discord->
egg. — yeah, whereas asking the game for topography below the trajectory can be done as a one-off task when the flight plan changes
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[Principia] Tutul- commented on issue #2788: [Question] Recommanded tool to simulate n-body to test modified system - https://git.io/Jkb17
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[Principia] eggrobin closed pull request #2799: Interrupt the orbit analysis if the mission duration changes - https://git.io/Jkdu9
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[Principia] eggrobin pushed 12 commits to master [+0/-0/±50] https://git.io/JkbD8
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[Principia] eggrobin 3aa692e - Cancel the analysis if the mission duration changes
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[Principia] eggrobin 5208b1d - make the orbit analyser interruptible
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[Principia] eggrobin 3bac1c4 - flow once
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[Principia] ... and 9 more commits.
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[Principia] eggrobin commented on issue #2788: [Question] Recommanded tool to simulate n-body to test modified system - https://git.io/Jkbd4
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[Principia] pleroy opened pull request #2800: Change the apodization functions to be centred - https://git.io/JkbFw
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[Principia] Tutul- closed issue #2788: [Question] Recommanded tool to simulate n-body to test modified system - https://git.io/Jkug8
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[Principia] Tutul- commented on issue #2788: [Question] Recommanded tool to simulate n-body to test modified system - https://git.io/Jkbpu
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[Principia] pleroy commented on pull request #2800: Change the apodization functions to be centred - https://git.io/JkNvf
<discord->
egg. — @Butcher I am thinking of having a small blurb, e.g., « highly eccentric semisynchronous orbit » that describes the current orbit for the analyser (so that you can get some situational awareness without having the giant analysis page open at all times, and also to describe coasts when I add analysis to the flight plan—a prereq for the +1 rev. feature). Do you have any thoughts on what properties
<discord->
egg. — equatorial/nothing (probably not worth calling most orbits prograde or inclined)/polar/retrograde ? circular for e < 0.01 or so? what would be a good threshold for calling something highly eccentric?
<discord->
egg. — and then subsynch (specifically calling out semisynch)/synch/supersynch, and stationary if you are equatorial, circular, and synchronous?
<discord->
egg. — @Butcher I am thinking of having a small blurb, e.g., « highly eccentric semisynchronous Earth orbit » that describes the current orbit for the analyser (so that you can get some situational awareness without having the giant analysis page open at all times, and also to describe coasts when I add analysis to the flight plan—a prereq for the +1 rev. feature). Do you have any thoughts on what prop
<discord->
Butcher. — I'm not sure on a good threshold for highly eccentric, I don;t use them much it has to be said, I'm normally either on a hyperbolic flyby or something much closer to circular.
<discord->
egg. — yeah a lot of the fancier orbits don’t have much use with the current state of career
<discord->
Butcher. — Even sun synch gets used like once.
<discord->
egg. — yeah and probably not even because it is sun-synch
<discord->
Butcher. — There is specific contract for sun synch, but it;s just 97° with a reasonable period, it doesn't actually have to be synched.
<discord->
egg. — yeah, it’s just « go to that orbit » with flavour text
<discord->
Butcher. — As they all are really.
<discord->
egg. — a laudable effort, but not really interestingly about the sun-synchronicity
<discord->
egg. — (since the primary reasons for sun-synch in real life are lighting conditions in observation, which aren’t modelled, and power-hungry instruments, which aren’t a concern with instascience)
<discord->
egg. — (morning or afternoon orbits for the former, crepuscular for the latter)
<discord->
Butcher. — Kerbalism lacks insta science so power is a concern.
<discord->
Butcher. — But the RO way is just moar solar.
<discord->
egg. — lol
<discord->
egg. — similarly the ground track recurrence dance is of no concern if you do not need to regularly observe places, or to always have an opportunity to observe something « soon »
<discord->
Butcher. — Indeed, the closest ground track are to an issue is doing scansat stuff, and that just requires eventual coverage.
<discord->
Butcher. — I believe newer versions require daylight though.
<discord->
egg. — For equatorial/polar, would 1-degree tolerances make sense? (call sub-degree orbits equatorial, super-89 sub-91 polar)
<discord->
Butcher. — Yes, that would be reasonable.
<discord->
Butcher. — 1° is fairly loose, but adequate as a descriptor I think.
<discord->
lpg. — Sadly kerbalism doesn't acknowledge sun-sync orbits for unloaded vessel solar exposure purposes
<discord->
egg. — huh? I thought it was supposed to?
<discord->
Butcher. — It does in slow mode, but once you get to analytical mode it just assumes equatorial.
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<discord->
egg. — @Butcher how much drift would you allow to still call an orbit « synchronous » ?
<discord->
Butcher. — Hmm I'm not sure.
<umbralraptop>
Grab the elements of some actual sats, and use their drift?
<discord->
egg. — so for a GPS satellite (SVN G063, in plane D, slot 2) I’m getting a drift of 0°.029 over 10 days
<umbralraptop>
1.2 milliarcsec/sec
<umbralraptop>
...I suppose we should round up if anything
<umbralraptop>
also, how difficult is that to pull off with the current UI?
umbralraptop is now known as raptor
raptor is now known as umbralraptor
umbralraptor is now known as umbralraptop
<discord->
egg. — 0°.035 on a 北斗 GEO sat, 0°.35 北斗 IGSO sat, 0°.71 みちびき QZO, 0°.051 みちびき GEO
<discord->
Butcher. — IGSO?
<discord->
egg. — Inclined GeoSynchronous Orbit
<discord->
Butcher. — Inclined geosynch?
<discord->
egg. — eggsactly
<discord->
Chatz. — I managed to impact the moon in my rp-1 career with principia, but replicating it is hard - it looks like the inclination keeps dropping. Do I just need more delta V or is there something I'm missing here?
<discord->
Sumguy. — might be procession
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<discord->
Chatz. — Yeah, so what I'm doing is launching into the moon's LAN and lowering my inclination a couple degrees to my parking orbit - is there anything better I should be doing?
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<discord->
Sumguy. — lolwhoops
<discord->
moar ssto. — that's some big perturbation
<discord->
[experimentalshells?]. — launch into plane of moon, not LAN
<discord->
Damien. — launching into plane of moon is often not possible
<discord->
[experimentalshells?]. — then wait for when its possible
<discord->
Damien. — once every 18yrs?
<discord->
[experimentalshells?]. — no
<discord->
[experimentalshells?]. — twice every month
<discord->
Damien. — with principia?
<discord->
[experimentalshells?]. — think of the Moon's orbit as somewhat of a plane
<discord->
[experimentalshells?]. — it intersects the Earth through the center
<discord->
[experimentalshells?]. — the Earth is rotating, but its axis of rotation is not normal to that plane
<discord->
Chatz. — Yeah there's no way I can launch into the plane of the moon
<discord->
Damien. — you can't launch directly into an orbit that is lower than your latitude, which the moon's plane often is
<discord->
Damien. — you can intercept its orbit, but not by launching into a coplanar one
<discord->
[experimentalshells?]. — oh, maybe I've been playing too much kourou/wenchang
<discord->
Damien. — oh yeah from Kourou you're fine 😄
<discord->
[experimentalshells?]. — oh, maybe I've been playing too much kourou/wenchang, whoops (edited)
<discord->
Damien. — but from the default Cape, it's often a polar orbit transfer
<discord->
Damien. — or some other tricky trajectory
<discord->
Chatz. — but polar I have to park for a while, right?
<discord->
Damien. — read up on Korolev and the Luna missions
<discord->
Damien. — and get ready to rage at direct ascent missions
<discord->
Damien. — and get ready to rage at direct ascent (edited)
<discord->
Damien. — it is possible with no parking orbit, but it's lots of trial and error and timing
<discord->
Damien. — I believe @Butcher has a script for KOS that may help
<discord->
Damien. — If you read up on the Pioneer 0/1 missions they were lunar probes launched from the Cape
<discord->
Damien. — failed, but the plans worked
<discord->
Damien. — I recreated it once and then stopped playing ksp for months
<discord->
Butcher. — You run that and launch immediately into the orbit specified.
<discord->
Butcher. — It has not failed me yet.
<discord->
Butcher. — No waiting, 3120-3150 m/s intercept trajectories.
<discord->
Stonesmile. — I think the question was about a direct ascent to the moon, which I wouldn't recommend
<discord->
Butcher. — Direct ascent is a pain.
<discord->
Stonesmile. — That script otoh is *really* handy
<discord->
Damien. — > which I wouldn't recommend
<discord->
Damien. — agreed
<discord->
Butcher. — I have a direct ascent script, but it's more complicated to get a good intercept and there's a limited window each month.
<discord->
Butcher. — This script tends to work out cheaper as you can launch into less inclined parking orbits.
<discord->
lpg. — > but polar I have to park for a while, right?
<discord->
lpg. — this question _may_ mean "as opposed to direct ascent", but I think it's more likely that it meant "park for days instead of for at most one orbit"
<discord->
lpg. — Because people used to launching into the plane of the moon generally don't have direct ascent in mind
<discord->
Butcher. — Worst case you could need to park for two weeks I think?
<discord->
egg. — The Cape is a silly place, launch from somewhere nicer :-p
<discord->
lpg. — if you launch into the wrong LAN, yes
<discord->
Butcher. — From Polar I mean.
<discord->
Butcher. — @egg I use VAFB.
<discord->
lpg. — same thing
<discord->
Butcher. — Next play is definitely Mahia.
<discord->
Chatz. — Can you explain what this is actually doing? I don't understand
<discord->
Stonesmile. — Mahia is onöy -40 deg, gotta do better
<discord->
Stonesmile. — Mahia is only -40 deg, gotta do better (edited)
<discord->
Stonesmile. — @egg Mahia is where Rocket labs launch complex in NZ is located
<discord->
egg. — ah
<discord->
Stonesmile. — @Chatz It creates a plane containing three points; the rocket, the moon in four days, and the center of Earth. It then returns the inclination to launch into to get into that plane
<discord->
Chatz. — do I still launch into the LAN of the moon?
<discord->
Stonesmile. — You are supposed to launch as soon as the script is run, launching into the inclination it tells you
<discord->
Stonesmile. — I guess they go by the polar circle, which is at 66 deg on that page?
<discord->
Butcher. — No, you just launch immediately.
<discord->
Chatz. — got it, I'll have to play around with that. The attempts I'm doing now are to launch into the LAN of the moon and ending up being 5 or 6 degrees inclination off
<discord->
Butcher. — You end up with something like this:
<discord->
egg. — back to the (sub)synchronous longitudes, the criterion would be 0°.1 per day? that means, in theory, 36° drift over a year (but then a monthly control cycle is not unreasonable, and that keeps you within a couple of degrees, which is consistent with the criterion we chose for inclination)
<discord->
lpg. — > got it, I'll have to play around with that. The attempts I'm doing now are to launch into the LAN of the moon and ending up being 5 or 6 degrees inclination off
<discord->
lpg. — there may still be some confusion here. there's _no_ expectation, with any of these methods, to end up with any particular inclination relative to the moon.
<discord->
Butcher. — Nor should you need to. You can launch into any lunar orbit you need with minor tweaks of earth departure velocity and timing.
<discord->
Chatz. — understood, but if I launch into the LAN of the moon, I'd want to reduce the relative inclination, right?
<discord->
Butcher. — e.g. I just tweaked that TLI burn shown by 0.692 m/s and 64 seconds and instead of impact I'm aiming for a high polar orbit.
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<discord->
egg. — hmm, that 北斗 GEO satellite has an inclination of about 1°.42, so 1° is way too tight for equatoriality
<discord->
egg. — OK let’s say 80° to 100° for polar (this is a short description so we’re not going to explicitly say quasi, and they are definitely called at least quasi-polar in that range)
<discord->
egg. — OK but on the other hand, the QZSS specification says 0 ± 0.1 degrees for the latitude of their GEO satellite
<discord->
egg. — Capderou has the sentence
<discord->
egg. — > À partir de 1990, les satellites météorologiques sont sur une orbite quasi équatoriale (i < 1.5°)
<discord->
egg. — and
<discord->
egg. — > Si i = 0° (ou i = 180°, mais ce cas n'a jamais été rencontré), on parle d'orbite *équatoriale*, et pour i inférieur à 10°, d'orbite *quasi équatoriale*.
<discord->
Stonesmile. — How far from 0° can a geo sat be before it causes issues for ground tracking? (I assume the answer is
<discord->
Stonesmile. — How far from 0° can a geo sat be before it causes issues for ground tracking? (I assume the answer is 'it depends') (edited)
<discord->
egg. — probably it depends, and also not all GEO sats are GEO because of dishes on houses
<discord->
egg. — e.g. meteorology sats, GNSS sats, etc. don’t care about your parabolae
<discord->
egg. — (and house dishes are very lax aiui)
<discord->
Stonesmile. — How set in stone are these definitions when you have implemented them? If a different consensus is reached later, could it be changed?
<discord->
egg. — yes, but since everything is fuzzy it would be changing a fuzzy thing to another fuzzy thing :D
<discord->
egg. — another way to look at it would be that the lowest-inclination doglegless launch from Kourou should probably be classified as equatorial, so 10° is not insane (Kourou is at 5°.5 or so, right?)
<discord->
Stonesmile. — If I have understood things correctly, KC might be the driving factor for the definitions?
<discord->
egg. — 5°.15
<discord->
egg. — nah, those definitions are just to give you a little blurb in Principia to tell you what is going on
<discord->
egg. — the goal of KC is precisely to avoid having the contract telling you to be in such-and-such orbit, because that is silly
<discord->
egg. — you don’t go into a sufficiently-sun-synchronous orbit because the contract says so and says how synchronous it needs to be, you go there because you get more observation time with appropriate solar angle
<discord->
Stonesmile. — Yeah, I have already read that doc, looking forward to when sirMortimer has time to put into it
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<discord->
Butcher. — It's a bit like a good version of the scansat contracts
<discord->
Chatz. — @Butcher Just tried out your script - the output was 51 degrees south - that's a couple thousand more delta V to orbit though, right?
<discord->
Stonesmile. — Should be about 50 m/s more than east
<discord->
Stonesmile. — (or 100 m/s)
<discord->
Chatz. — Hmm, 51 degrees south means I put -51 degrees inclination into PVG?
<discord->
Stonesmile. — Correct
<discord->
Chatz. — Ok, the burn was way more expensive
<discord->
Chatz. — it burned somewhat retrograde
<discord->
Chatz. — let me test again
<discord->
Chatz. — Ok this burn is looking way better
<discord->
Butcher. — The most expensive orbit should be polar which is a few hundred m/s more than east.
<discord->
Butcher. — It will never generate retrograde orbits.
<discord->
Chatz. — It must have been something I messed up or PVG did then
<discord->
Chatz. — Second attempt looks fine
<discord->
Butcher. — Typo in pvg maybe.
<discord->
Butcher. — Once in orbit make a flight plan of around 5 days, set 3140 m/s tangent and move the time slider until you hit the moon. Might need to tweak the dv slightly depending on where the moon is in its orbit.
<discord->
Chatz. — These final burns are really tricky for my setup because I just spin stabilize
<discord->
Stonesmile. — Doing unguided TLI can be done, but being unguided when you get to a parking orbit seems near impossible, if that is what you do
<discord->
Chatz. — Yeah its the TLI that's unguided
<discord->
Chatz. — I hit it on my first lunar mission, but have failed a few more since
<discord->
Chatz. — I try and just plan a maneuver to use all my delta v and then fine-tune with forward/backwards rcs but sometimes I can't get the periapsis lower than a few million meters
<discord->
Stonesmile. — That's the limitations of the early tech in RP-1