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
<discord-> l​pg. — eek. Mercury eats probes too
<discord-> l​pg. — Sadly the reason I thought to check this is that the backup probe has gone missing. Gotta form some better habits 😞
<discord-> e​gg. — Huh
<discord-> e​gg. — https://svs.gsfc.nasa.gov/4258
<discord-> e​gg. — I don't think we had looked into what the gravitational field looked like, we just blindly imported the MESSENGER data; but it seems it is lumpy indeed
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<discord-> l​pg. — Meanwhile one venus probe's Pe was down to 80km and it will only survive because it wasn't there when I happened to load it. Not sure if that was also the planet trying to eat it or just me having forgotten to raise Pe last time and having been spared by KSP's peculiar handling for unloaded vessels in atmo
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<discord-> e​gg. — I thought venus was about as spherical as things get
<discord-> e​gg. — well, at least it has no J2, I don’t know whether it is lumpy
<discord-> e​gg. — well, at least it has no appreciable J2, I don’t know whether it is lumpy (edited)
<_whitenotifier-9244> [Principia] pleroy labeled pull request #2813: Avoid overflow - https://git.io/JInmk
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<_whitenotifier-9244> [Principia] pleroy opened pull request #2814: Support for pass-band mode and Mathematica traces in the analytical series test - https://git.io/JIWki
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<_whitenotifier-9244> [Principia] pleroy synchronize pull request #2814: Support for pass-band mode and Mathematica traces in the analytical series test - https://git.io/JIWki
<_whitenotifier-9244> [Principia] eggrobin commented on issue #2811: Crash while descending towards the surface of a body - https://git.io/JIWL8
<_whitenotifier-9244> [Principia] Pending. Build queued… - 
<_whitenotifier-9244> [Principia] Pending. Building… - http://casanova.westeurope.cloudapp.azure.com:8080/job/Principia/4674/
<discord-> e​gg. — @Butcher are you sure you gave me the correct journal? I can’t replicate the failure by replaying it
<_whitenotifier-9244> [Principia] Failure. Build finished. - http://casanova.westeurope.cloudapp.azure.com:8080/job/Principia/4674/
<discord-> e​gg. — @ferram4 I got this bug report about an aircraft that behaves differently with Principia and I'm not quite sure what to make of it https://github.com/mockingbirdnest/Principia/issues/2808#issuecomment-738409742; are you aware of cases where the rigid body dynamics of an aircraft (in the sense of "how it freely rotates", e.g., Джанибекв effect etc.) matter for its handling characteristics?
<discord-> e​gg. —
<discord-> e​gg. — The issue is very poorly phrased but essentially these forward-swept aircraft fly stably in stock (though possibly not by much) and with Principia they handle very nervously and would definitely benefit from a FBW system.
<discord-> e​gg. —
<discord-> e​gg. — Could be a silly bug obviously, but I was wondering whether it could just be the fact that pitch will induce roll in a freely-spinning aircraft in a way that stock does not correctly model
<_whitenotifier-9244> [Principia] pleroy synchronize pull request #2814: Support for pass-band mode and Mathematica traces in the analytical series test - https://git.io/JIWki
<_whitenotifier-9244> [Principia] Pending. Build queued… - 
<_whitenotifier-9244> [Principia] Pending. Building… - http://casanova.westeurope.cloudapp.azure.com:8080/job/Principia/4675/
<_whitenotifier-9244> [Principia] Success. Build finished. - http://casanova.westeurope.cloudapp.azure.com:8080/job/Principia/4675/
<discord-> f​erram4. — @egg I'm guessing by "stock" you mean "FAR-no-Principia," just for clarity's sake?
<discord-> e​gg. — FAR RO non-Principia, even
<discord-> e​gg. — (stock has acquired a strange meaning here :-p)
<discord-> f​erram4. — I can think of many situations where rigid body dynamics would affect the dynamic stability as far as aerodynamics goes, but I gather the problem here is that it's affecting static stability
<discord-> f​erram4. — And in that case rigid body dynamics is basically limited to, "where is center of mass", IIRC
<discord-> B​utcher. — @egg fairly sure. 🤔
<discord-> e​gg. — static stability being the behaviour when the aircraft does not change attitude in the airflow?
<discord-> f​erram4. — Yes. A statically stable aircraft is one where you take the hands off the yoke and it flies nice and level (for some definition of level and nice)
<discord-> e​gg. — yeah, that one does in stock
<discord-> f​erram4. — As opposed to a statically unstable craft, where it pitches or yaws or whatevers out of control
<discord-> e​gg. — (well, I have a stick, what am I, a boeing pilot?)
<discord-> f​erram4. — Regardless of what the initial conditions are
<discord-> e​gg. — right
<discord-> f​erram4. — Now, a statically stable craft can be dynamically unstable, and that usually means the init conditions matter
<discord-> f​erram4. — A lot
<discord-> f​erram4. — But... if that's not the case here, I'm confused
<discord-> e​gg. — it may be that we are in the "stupid bug" regime then
<discord-> f​erram4. — Like, that craft should have fly by wire anyway
<discord-> e​gg. — some mod doing something to some centre of mass
<discord-> f​erram4. — It's barely stable
<discord-> f​erram4. — No pilot would want to fly that
<discord-> e​gg. — yeah, but it actually does fly hands-off the stick in stock
<discord-> f​erram4. — Hrm
<discord-> f​erram4. — Did he send logs?
<discord-> e​gg. — (don't put it in a spin though, or pack some parachutes)
<discord-> f​erram4. — I'm guessing if I'm asking the answer is no
<discord-> e​gg. — no logs but I have the crafts and managed to replicate installs where I flew them myself
<discord-> f​erram4. — Oh, better
<discord-> e​gg. — (took me an hour and a half as I complain in my reply :-p)
<discord-> f​erram4. — I gather you've done the standard, "are there any exceptions" check?
<discord-> e​gg. — ... oh, let me check
<discord-> e​gg. — (in Principia there are no exceptions, if it has not crashed to desktop we are happy :-p)
<discord-> f​erram4. — Remember, KSP and non-Principia mods will fail "gracefully"
<discord-> f​erram4. — Graceful as a hippo dancing through a china shop, but the gracefulness does hide whether it's a hippo, an elephant, or a rhino
<discord-> e​gg. — hm, a couple of exceptions but I think that is from missing mods when loading the craft (I have enough to replicate but not quite as many mods as the bug reporter had). no exception spam
<discord-> f​erram4. — Depending on what they are, those exceptions can interrupt some things that could affect where the CoM is placed
<discord-> f​erram4. — Especially since the VAB and flight are different
<discord-> f​erram4. — Because REASONS
<discord-> e​gg. — Hm. then again you would get those same exceptions with Principia
<discord-> e​gg. — so I guess the question is more "is there something nudging the centre of mass in ways that we do not know about" then
<discord-> f​erram4. — FAR does have some logic that changes the mass of wings based on how large they are and how they're connected, and a slider for strength. Something to try and fix the rather silly weights of stock wings
<discord-> f​erram4. — But that should be applied directly to the part.mass property
<discord-> f​erram4. — Or something like that
<discord-> f​erram4. — And PWings should respect that
<discord-> f​erram4. — @egg If that is the issue, and you're not getting mass correctly, would that result in the predicted and true trajectories diverging in a vacuum?
<discord-> f​erram4. — Because of the force being applied wrong
<discord-> e​gg. — yeah if the centre of mass is wrong that is sufficient to explain any issue, you will have different forces etc.
<discord-> f​erram4. — I sense a quick check is, "make big PWings craft see how that diverges from what's expected"
<discord-> e​gg. — I suppose the quickest check of wrong-centre-of-mass would be to plot the centre of mass according to Principia
<discord-> e​gg. — @Butcher what kind of trajectory were you on during that descent? my attempt at replicating fails because the integrator detects the collision, terminates, and thus there is no orbit to analyse
<discord-> B​utcher. — Apoapsis about 10 Mm above the Lunar North Pole, ground intercept close to the equator.
<discord-> e​gg. — hm
<discord-> e​gg. — with that apoapsis I get down to ν=46 before the integrator notices that we are inside the moon, and 46 is quite far below 2 billion
<discord-> B​utcher. — Hmm
<discord-> e​gg. — can you perhaps add a LOG(INFO)<<κ; in the code I mentioned and try to replicate it, to see if I diagnosed it correctly?
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<discord-> B​utcher. — Sure I'll have a poke at it tomorrow.
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<discord-> e​gg. — thanks, I’ll keep poking on my side, as well ; it may well be that my pending PR fixes it, but I’d like to make sure that I understood the problem correctly, lest I hide it instead of fixing it…
<_whitenotifier-9244> [Principia] eggrobin labeled pull request #2814: Support for pass-band mode and Mathematica traces in the analytical series test - https://git.io/JIWki
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<discord-> B​utcher. — Log at orbit_recurrence_body.hpp line 74?
<discord-> e​gg. — might as well log as early as line 60
<discord-> e​gg. — it’s not like κ can change
<discord-> B​utcher. — True.
<discord-> B​utcher. — `version is 2020111505-╨ô╨╡╨╗╤î╤ä╨░╨╜╨┤-135-g4c1d15c72214200426e1b8aefff58316f5cfa5fe-dirty` VS really does well with unicode...
<discord-> e​gg. — hah
<discord-> e​gg. — I wonder if there is a way to chcp in that console
<discord-> B​utcher. — Just building with your changes and that logging.
<discord-> e​gg. — the problem with logging-based debugging is that every trace raises more questions that need more traces to be answered, and the build times are not great :-p
<discord-> e​gg. — (though I understand you actually have a pretty good machine on that front)
<discord-> B​utcher. — Until you end up logging so much the problem vanishes because the logging has had too much impact.
<discord-> e​gg. — I really hope this is something deterministic and not a data race
<discord-> e​gg. — the fact that you are able to reproduce it is encouraging
<discord-> e​gg. — the fact that I am not is not
<discord-> B​utcher. — I can't reproduce it 100%.
<discord-> B​utcher. — Here we go...
<discord-> B​utcher. — Hmm, the orbit might not be as above, since it occurs during the braking manoeuvre.
<discord-> B​utcher. — No logging of κ so far. Is that expected?
<discord-> e​gg. — hm
<discord-> e​gg. — the info log is buffered so maybe that is it?
<discord-> e​gg. — is the orbit analysis button saying things?
<discord-> B​utcher. — I've done one full run and am on the second.
<discord-> e​gg. — that is odd, it should spam info
<discord-> B​utcher. — OK, this run I did get some spam.
<discord-> e​gg. — whee
<discord-> e​gg. — how large does it get
<discord-> B​utcher. — `I1206 21:01:49.984436 18112 orbit_recurrence_body.hpp:65] 6.79752` appers to be the highest value
<discord-> B​utcher. — `I1206 21:01:49.984436 18112 orbit_recurrence_body.hpp:65] 6.79752` appears to be the highest value (edited)
<discord-> e​gg. — OK that is consistent with your journal
<discord-> e​gg. — and noticeably below two billion
<discord-> B​utcher. — Indeed.
<discord-> B​utcher. — Orbit is likely to be something like apoapsis 25-35 km above surface, about 0°15' north of the equator at that point.
<discord-> B​utcher. — No crashes this far.
<discord-> B​utcher. — No crashes thus far. (edited)
<_whitenotifier-9244> [Principia] eggrobin commented on issue #2811: Crash while descending towards the surface of a body - https://git.io/JIWDE
<discord-> B​utcher. — `6.89917` that run, still exactly as expected. Hmm.
<discord-> e​gg. — OK I just reran your journal and
<discord-> e​gg. — ```
<discord-> e​gg. — E1206 22:10:38.170887 26916 orbit_recurrence_body.hpp:73] κ=-3.57064e+207
<discord-> e​gg. — E1206 22:10:38.173092 26916 orbit_recurrence_body.hpp:75] νₒ=-2147483648
<discord-> e​gg. — ```
<discord-> e​gg. — previously
<discord-> e​gg. — ```
<discord-> e​gg. — E1206 22:10:38.119838 26916 orbit_recurrence_body.hpp:73] κ=-101.819
<discord-> e​gg. — E1206 22:10:38.119838 26916 orbit_recurrence_body.hpp:75] νₒ=-102
<discord-> e​gg. — ```
<discord-> B​utcher. — Hmm, data race?
<discord-> e​gg. — quite possibly
<discord-> s​cimas. — A race with no winners 😞
<_whitenotifier-9244> [Principia] pleroy pushed 2 commits to master [+0/-0/±2] https://git.io/JIWQq
<_whitenotifier-9244> [Principia] pleroy 6e1b3d1 - Termination check.
<_whitenotifier-9244> [Principia] pleroy 8e78f51 - Merge pull request #2812 from pleroy/Termination Termination check in frequency analysis
<_whitenotifier-9244> [Principia] pleroy closed pull request #2812: Termination check in frequency analysis - https://git.io/JIZhY
<_whitenotifier-9244> [Principia] pleroy closed pull request #2814: Support for pass-band mode and Mathematica traces in the analytical series test - https://git.io/JIWki
<_whitenotifier-9244> [Principia] pleroy pushed 7 commits to master [+0/-0/±19] https://git.io/JIWQK
<_whitenotifier-9244> [Principia] pleroy 5b22373 - New Mathematica helpers.
<_whitenotifier-9244> [Principia] pleroy e50262e - Improved Mathematica logging, including CPU usage.
<_whitenotifier-9244> [Principia] pleroy b6beb37 - Clean up duration bounds.
<_whitenotifier-9244> [Principia] ... and 4 more commits.
<discord-> e​gg. — I am also seeing apoapsides on the order of 1000 au and periapsides on the order of -1000 au
<discord-> B​utcher. — Principia builds are so fast compared to UE4. :-p
<discord-> e​gg. — so *something* is very wrong
<discord-> B​utcher. — Er, yes.
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<discord-> l​pg. — > periapsides on the order of -1000 au
<discord-> l​pg. — I want to play in a system with a star big enough for that to make sense
<discord-> e​gg. — @lpg that is periapsis distance, not altitude, so it fundamentally does not make sense
<discord-> l​pg. — in-game periapsis _is_ altitude
<discord-> e​gg. — yeah, but here it is the periapsis distance that I am logging
<discord-> e​gg. — @Butcher I don’t think it is a data race, but it is definitely some flavour of UB
<discord-> e​gg. — and obviously the more logs I add the less reproducible it is :D
<discord-> B​utcher. — I was unable to reproduce a crash today.
<discord-> e​gg. — I guess the log protects you 🙃
<discord-> B​utcher. — Or even log an unexpected κ.
<discord-> S​tonesmile. — The history of a L2 relay gets quite noisy...
<discord-> B​utcher. — I killed my L2 relay, took too much maintenence
<discord-> S​tonesmile. — The thought has crossed my mind 😪
<discord-> B​utcher. — My current farside rover, apart from being a Principia crash test vehicle, just brought its own orbital relay.
<discord-> S​tonesmile. — Yeah, a couple hundred kg of extra TLI mass the next time I need a relay isn't too bad...
<discord-> B​utcher. — Not sure it was even that much, science core and two dishes.
<discord-> B​utcher. — Oh and solar.
<discord-> S​tonesmile. — I might send it on a voyage to other lagrange points... that might be fun
<discord-> B​utcher. — I assume my test build with style changes is working for you?
<discord-> B​utcher. — I'm thinking I'll create the pr tomorrow.
<discord-> S​tonesmile. — Yeah, it's working, I haven't encountered any issues
<discord-> e​gg. — so, replaying the journal doesn’t crash deterministically and also it takes 5 minutes