raptop changed the topic of #principia to: READ THE FAQ: http://goo.gl/gMZF9H; The current version is Fréchet. We currently target 1.5.1, 1.6.1, and 1.7.x. <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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<_whitenotifier-d13c> [Principia] pleroy commented on issue #2515: Mark Station keeping to be broken with Principia - https://git.io/Jvba7
<_whitenotifier-d13c> [Principia] pleroy closed issue #2515: Mark Station keeping to be broken with Principia - https://git.io/Jv7NC
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<_whitenotifier-d13c> [Principia] sthalik commented on issue #2324: Suggestion: don't remove the last manœuvre node from the navball - https://git.io/Jvbwc
<discord-> e​gg. — I now have an input method with which I can ping @𒀯 𒄷 𒄈𒀭𒁇 :-p
<discord-> S​ir Mortimer. — And there he was thinking he’s safe from pings 🙂
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<discord-> e​gg. — @Sir Mortimer so you asked me about GPS DOP, I don’t quite remember where we were last time wrt that
<discord-> e​gg. — did I give you some usable formulae ?
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<discord-> S​tandecco. — how do even you input cuneiform?
<discord-> S​tandecco. — and how does egg's keyboard switch interface look? Mine's already pretty crowded and I only have 4 alphabets
<discord-> S​tandecco. — "crowded" as in "I constantly get confused and input whole sentences with the wrong alphabet when I have to write a single γ"
<discord-> n​eph. — Egg uses two keyboards, one to typewith and the other to switch layouts
<discord-> n​eph. — Egg uses two keyboards, one to type with and the other to switch layouts (edited)
<discord-> S​tandecco. — egg's keyboard
<discord-> A​cer_Saccharum. — There's a registry key in windows that lets you type most Unicode characters
<discord-> e​gg. — @Standecco I made a cuneiform IME, none exists that I know of
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<discord-> 𒀯​ 𒄷 𒄈𒀭𒁇. — /me screams in bird
<discord-> 𒀯​ 𒄷 𒄈𒀭𒁇. — *screams in bird* (edited)
<discord-> 𒀯​ 𒄷 𒄈𒀭𒁇. — Apparently /me is broken?
<discord-> e​gg. — hm
* discord- 𒀯​ 𒄷 𒄈𒀭𒁇. — stabs things_
<discord-> 𒀯​ 𒄷 𒄈𒀭𒁇. — ...that worked
<discord-> 𒀯​ 𒄷 𒄈𒀭𒁇. — As far as IMEs go, that reminds me. I need to add US-Int to my keyboard layouts and fix the Japanese one on this raptop
<discord-> S​ir Mortimer. — and so it begins...
<discord-> e​gg. — 🛰️ 🚢
<discord-> n​eph. — I believe Principia to be causing nonphysical rotations upon vehicles in the atmosphere at high dynamic pressure during time warp. It's been reported by multiple people before I started looking into it, and I can't find any aero (drag/lift) related cause. This is the behavior: https://youtu.be/dNHiZsGIurg?t=76
<discord-> n​eph. —
<discord-> n​eph. — This does not occur at timewarp 1x or with Principia removed. Just flew the exact same rocket, same profile, principia removed. No issues even at 4x the whole way down.
<discord-> n​eph. — For sounding rockets it's not the end of the world, but I fear it will be very frustrating to work around during crewed reentries
<discord-> e​gg. — is this new in Frobenius?
<discord-> n​eph. — it is.
<discord-> n​eph. — If there's any testing/data gathering I can do let me know
<discord-> e​gg. — hmm
<discord-> e​gg. — does your rocket lose mass in any way in that process
<discord-> e​gg. — e.g. engines firing or something else
<discord-> n​eph. — It doesn't.
<discord-> D​RVeyl. — No fuel to boil off, no heatshields to ablate. Tho both of those would be likely later cases.
<discord-> e​gg. — hm
<discord-> n​eph. — My guess is that either physics timewarp and principia are fighting or the torques introduced by lift & drag make it unstable
<discord-> n​eph. — My guess is that either physics timewarp and principia are fighting or the torques introduced by lift & drag make it the system unstable somehow. Rotations in vacumn all seem fantastic (edited)
<discord-> n​eph. — My guess is that either physics timewarp and principia are fighting or the torques introduced by lift & drag make it the system unstable somehow. Rotations in vacuum all seem fantastic (edited)
<discord-> e​gg. — OK so a cursory glance at @ferram4’s code seems to show that he is applying forces cleanly (that is, in a way that we handle properly) so any change that he imparts to the angular momentum should be reflected in what we think of the vessel
<discord-> e​gg. — OK so a cursory glance at @ferram4’s code seems to show that he is applying forces and torques cleanly (that is, in a way that we handle properly) so any change that he imparts to the angular momentum should be reflected in what we think of the vessel (edited)
<discord-> e​gg. — but then that would mean that the vessel should be spinning… what prevents it from doing so normally
<discord-> e​gg. — @neph you say that the issue is only visible when physics-warping?
<discord-> D​RVeyl. — (Referring to ferram's code, you are examining it from https://github.com/dkavolis/Ferram-Aerospace-Research/releases correct?)
<discord-> n​eph. — Indeed. There's something else weird at play (the start of that video shows it picks up a slight roll on ascent, and this is still there without principia; confirmed by others as well), but without physics warp it doesn't wig out like that. Just punches through the atmosphere normally
<discord-> n​eph. — Indeed. There's something else weird at play (the start of that video shows it picks up a slight roll on ascent, this is still there without principia; confirmed by others as well), but without physics warp it doesn't wig out like that. Just punches through the atmosphere normally (edited)
<discord-> n​eph. — Indeed. There's something else weird at play (the start of that video shows it picks up a slight roll on ascent, this is still there without principia; confirmed by others as well. My suspicion: something to do with b9 pwings), but without physics warp it doesn't wig out like that. Just punches through the atmosphere normally (edited)
<discord-> e​gg. — @DRVeyl no because that is not searchable
<discord-> e​gg. — if any nontrivial changes have been made that are not correct, screw those changes
<discord-> f​erram4. — The "something weird" on ascent is probably the rocket not being 100% completely symmetric or taking off perfectly vertically or something like that
<discord-> f​erram4. — Physics sims can magnify small little errors into big errors
<discord-> e​gg. — yeah, the uncontrolled spin-up on descent seems odd though
<discord-> e​gg. — we accumulate angular momentum from the forces & torques given to us, and enforce that
<discord-> f​erram4. — With the way it was flailing, I'd almost suspect something involving the vehicle deforming
<discord-> e​gg. — so something would need to tell us to keep spinning the thing up...
<discord-> f​erram4. — In large deflections the joint sims seem to somehow become non-conservative
<discord-> f​erram4. — Unless things have changed since I stopped doing stuff
<discord-> n​eph. — @ferram4 I tested all that. Behaves perfectly normally in 1.7.3.
<discord-> n​eph. — Is @dkavolis on this server?
<discord-> n​eph. — Guess not
<discord-> e​gg. — @ferram4 we enforce conservation now so if anything this should get better
<discord-> f​erram4. — It's KSP and Unity, I trust nothing 😛
<discord-> e​gg. — that is, nothing will change the overall angular momentum of the vessel except Part.Add(Force|Torque)
<discord-> e​gg. — you need not trust either
<discord-> e​gg. — We do not
<discord-> e​gg. — We ignore what they think and override it
<discord-> e​gg. — that is the main new feature in Frobenius
<discord-> f​erram4. — Hrmmm
<discord-> e​gg. — https://youtu.be/QWiRvKfe3SE
<kmath> YouTube - Principia Frobenius—Conservation of angular momentum
<discord-> f​erram4. — @egg Do you also account for Part.AddForceAtPosition?
<discord-> e​gg. — yes
<discord-> f​erram4. — Ok, no idea then
<discord-> M​yshiko. — @neph i report “odd crazy spins” on new Principia on low atmosphere on reentry as well
<discord-> f​erram4. — I did a quick look through dkavolis' source and unless he's adding forces somewhere else as well, it should only go through Part.AddForce, Part.AddTorque, or Part.AddForceAtPosition
<discord-> e​gg. — and in the FAR world stock no longer applies any aerodynamic forces?
<discord-> e​gg. — (i.e. are we now ignoring a stock force that would damp that effect)
<discord-> f​erram4. — It should not
<discord-> f​erram4. — I hope it doesn't, last I knew everything was shut off
<discord-> f​erram4. — "Quick" way to check: remove FAR, see if issue still occurs
<discord-> e​gg. — @Myshiko also only in physics warp?
<discord-> n​eph. — I'll try that.
<discord-> M​yshiko. — Low atmosphere is on physics warp only. I only seen it on high-g reentries, airplanes behave normally
<discord-> n​eph. — Also: I'm running dkavolis's dev branch of FAR due to it fixing some drag bugs. Might be irrelevant
<discord-> M​yshiko. — Low atmosphere and on physics warp only. I only seen it on high-g reentries, airplanes behave normally (edited)
<discord-> M​yshiko. — I’ve seen spins so crazy, the parts start to be rendered detached and moving out.
<discord-> e​gg. — yeah that is what happens in @neph's video as well
<discord-> e​gg. — @ferram4 could it be an effect that is genuinely in FAR but damped by some limitation of the physics engine
<discord-> M​yshiko. — I’ve tested on 1.8.1 RO/RP-1/RSS
<discord-> e​gg. — i.e., what physical effect would damp such a spin IRL, and does FAR model it
<discord-> A​cer_Saccharum. — does FAR calculate forces based on the individual velocities of each part?
<discord-> f​erram4. — It has to do that. Or else there's no aerodynamic damping at all
<discord-> M​yshiko. — Has somebody reversed an air dynamic dampening sign?
<discord-> f​erram4. — @egg I have no idea,
<discord-> A​cer_Saccharum. — and I'd also assume spinning cylinders would have some angular drag in FAR as well?
<discord-> f​erram4. — There's nothing to reverse
<discord-> M​yshiko. — Because it looks exactly like aerodynamic spin
<discord-> M​yshiko. — When I tilt the fins
<discord-> f​erram4. — There's no "aero damping sign". It arises organically from the simulation
<discord-> e​gg. — OK please unless you know something about FAR or have data to provide about the issue, shut up
<discord-> e​gg. — speculation is noisy and not helpful
<discord-> M​yshiko. — Sure 🙂 just sharing my observations. But I’m sure you can just see it from the logs.
<discord-> n​eph. — Would it be helpful for me to try to get dkavolis over here? I've been working with him to nail down some issues and he's quite cooperative
<discord-> e​gg. — Is there skin drag in FAR?
<discord-> f​erram4. — Another thing to check: the same rocket design, but with some kind of pitch/yaw/roll control to align it with the relative prograde before entering the atmosphere
<discord-> f​erram4. — If doing that removes the spin, then it's something aerodynamic
<discord-> f​erram4. — And probably means that something is up in either the wing/fin simulation or that the voxelization is uneven
<discord-> n​eph. — I'll try that after I do this run sans-far
<discord-> f​erram4. — Then that leads to diving into that to see which is borked. I'd suspect the voxelization, that can end up finicky sometimes
<discord-> e​gg. — it is odd though that it would not occur in the absence of Principia
<discord-> f​erram4. — Yes, that is odd
<discord-> e​gg. — since, iirc, the inane angular velocity limit of Unity is no longer activated
<discord-> f​erram4. — Does Principia assume no deflection or distortion of the vehicle when applying forces?
<discord-> e​gg. — also the timewarp-only thing is suspicious
<discord-> e​gg. — > Does Principia assume no deflection or distortion of the vehicle when applying forces?
<discord-> e​gg. — hm
<discord-> e​gg. — Principia does not really apply forces
<discord-> e​gg. — Principia measures total torque on the closed system
<discord-> f​erram4. — But you do grok what I'm getting at, right?
<discord-> e​gg. — not quite, unfortunately
<discord-> e​gg. — torque is given to us directly
<discord-> f​erram4. — The parts might not be exactly where you think they are when you're measuring the forces and torques to apply
<discord-> e​gg. — hmm
<discord-> e​gg. — could we have an off-by-one-frame silliness there
<discord-> f​erram4. — Which would then explain the high physics warp being needed, since that would exacerbate those errors
<discord-> n​eph. — It's not doing it sans FAR
<discord-> e​gg. — okay that is, uh, Interesting
<discord-> f​erram4. — Thank you, so it's some sort of interaction
<discord-> e​gg. — hm
<discord-> e​gg. — very odd
<discord-> f​erram4. — @neph Reinstall FAR, get the rocket pointed prograde for reentry, minimize all angle of attack and see what happens
<discord-> n​eph. — Granted, the fins are burned off before reentry
<discord-> n​eph. — Granted, the fins are burned off before reentry, so if it has something to do with b9 pwings, that isn't represented. (edited)
<discord-> n​eph. — Roger roger
<discord-> e​gg. — it burneth, burneth, burneth,
<discord-> n​eph. — With or without Principia?
<discord-> f​erram4. — With
<discord-> e​gg. — Yeah we can have some confidence in stock + FAR working
<discord-> e​gg. — has been tested by many for a while now
<discord-> e​gg. — (stock being RO in this context, amusingly)
<discord-> n​eph. — This will take a bit longer since I'll have to redesign things a bit
<discord-> n​eph. — Now you sound like you live on this server 🙂
<discord-> f​erram4. — If it was just an off-by-one-frame error, wouldn't that result in non-conservation that would be noticeable on the map?
<discord-> e​gg. — I think our handling of forces, i.e., the derivative of total linear momentum, is correct (unless a recent refactoring broke things a lot)
<discord-> e​gg. — their points of application (lever arms, torques), otoh
<discord-> e​gg. — that is new
<discord-> f​erram4. — Oh, you're in for a FUUNNNNN time 😄
<discord-> e​gg. — but I think we are doing something consistent with the game, so it is very odd that we see a difference
<discord-> e​gg. — even odder if the difference is FAR dependent O_o
<discord-> f​erram4. — FAR can create much more extreme forces than stock
<discord-> f​erram4. — Because it's not caring about gamifying everything
<discord-> e​gg. — hehe
<discord-> f​erram4. — And only slightly concerned about, you know, breaking the sim
<discord-> e​gg. — do you do any AddTorque, or just AddForceAtPosition (to try to narrow where I stare)
<discord-> f​erram4. — An AddTorque in FARAeroPartModule
<discord-> f​erram4. — FARAeroPartModule is separate AddForce and AddTorque, FARWingAerodynamicModel is AddForceAtPosition
<discord-> e​gg. — Do non-wings have a FARWingAerodynamicModel
* discord- e​gg. — does not trust identifiers :-p_
<discord-> f​erram4. — They should not
<discord-> f​erram4. — Unless someone decided to be "clever"
<discord-> f​erram4. — I think the possibility can be disregarded for the time being
<discord-> e​gg. — am not in the same country as my machine that has a chance with RO (and won’t for a while, *gestures at circumstances*), will try to see if I can replicate in stock +FAR
<discord-> e​gg. — where here "stock" means non-RO principia
<discord-> e​gg. — I have strange definitions of "stock"
<discord-> d​kavolis. — I have not changed anything related to how FAR computes forces and applies them
<discord-> e​gg. — sounds good
<discord-> e​gg. — also, hi
<discord-> d​kavolis. — KSP might have changed something
<discord-> e​gg. — tbh, the issue is most likely that *we* changed
<discord-> n​eph. — Ensure you are watching in HD. Here is the first attempt of a guided version. I suspect this was just due to this horrible plump design being unstable at high mach https://gfycat.com/criminalpastcollie
<discord-> d​kavolis. — For instance, it started resetting shielded state since 1.8 if no airstream shield were present for the part...
<discord-> d​kavolis. — For instance, it started resetting shielded state since 1.8 if no airstream shields were present for the part... (edited)
<discord-> e​gg. — @neph that first stage burns fast
<discord-> n​eph. — That's how aerobees do
<discord-> n​eph. — Sorry, this is taking longer than I anticipated.
<discord-> n​eph. — Uploading to youtube now.
<discord-> e​gg. — @neph also what is your github username so I may @ you on the issue
<kmath> YouTube - Unphysical warp, FAR/Debug GUIs open, Timewarping through Descent, Guided test 2
<discord-> n​eph. — nepphhh
<discord-> n​eph. — This one disintegrated on descent (due to being much denser with avionics) but the incredible spin still somehow emerged
<discord-> n​eph. — @ferram4 This one is oriented first. It seems normal until it breaks apart, after which the spin re-appears
<discord-> e​gg. — hm but it disintegrated before the spin appeared so this does not tell us much
<discord-> f​erram4. — The high spin after disintegrating is an artifact of the physics sim. Never really been anything we could do about it
<discord-> n​eph. — I don't have more time to test today, but when I do I think it'd be best to start with an actually-stock environment with FAR and Principia installed.
<discord-> n​eph. — RO makes things hard.
<discord-> f​erram4. — But that does seem to point at something going on with the other one since there was minimal spin before it went off prograde
<discord-> n​eph. — The other one is much lighter?
<discord-> f​erram4. — I doubt that was it
<discord-> f​erram4. — Neither one had too much inertia around their roll axis
<discord-> f​erram4. — Probably some not-quite-balanced something going on
<discord-> n​eph. — I'll try one more thing with something as perfectly balanced as I can make it
<_whitenotifier-d13c> [Principia] eggrobin opened issue #2519: Spin-up on reentry under physics warp with FAR - https://git.io/JvbAL
<_whitenotifier-d13c> [Principia] eggrobin labeled issue #2519: Spin-up on reentry under physics warp with FAR - https://git.io/JvbAL
<_whitenotifier-d13c> [Principia] eggrobin assigned issue #2519: Spin-up on reentry under physics warp with FAR - https://git.io/JvbAL
<discord-> d​kavolis. — You can see very small AoA and sideslip angles on launch, that may be enough to start it
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<discord-> e​gg. — @Myshiko are you Myshiko on GitHub?
<discord-> n​eph. — One more, perfectly balanced. https://gfycat.com/anchoredreflectingdodobird
<discord-> n​eph. — This very clearly demonstrates the immense amount of angular momentum it suddently picks up
<discord-> n​eph. — This very clearly demonstrates the immense amount of angular momentum it suddenly picks up (edited)
<discord-> n​eph. — I've narrowed the "weird little roll on ascent" issue down to the presence of PF fairing walls.
<_whitenotifier-d13c> [Principia] eggrobin edited issue #2519: Spin-up on reentry under physics warp with FAR - https://git.io/JvbAL
<discord-> e​gg. — @neph can you balance it pointing down into the airstream though
<discord-> e​gg. — it would be interesting to know whether it picks up that spin specifically because of the flip
<discord-> e​gg. — See also ferram's comment
<discord-> e​gg. — > But that does seem to point at something going on with the other one since there was minimal spin before it went off prograde
<discord-> n​eph. — I can't in the limitation of RO/RP-1, since there's no cheat to give avionics
<discord-> e​gg. — ah you are testing that on a career save?
<discord-> n​eph. — Further testing should happen in a near-stock environment.
<discord-> e​gg. — well, at least in sandbox...
<discord-> n​eph. — Not career per se, but in my career dev environment
<discord-> n​eph. — Actually sandbox should do it
<discord-> n​eph. — I need to make physics headway, I'll do it once I finish all this irl stuff
<discord-> D​RVeyl. — On that note about the part not being where you might think it is. I think ferram was referring to parts deflecting or deforming. But on a more simple view, are you accounting for non-zero part.CoMoffset ? More specifically, cases where the center of mass of the part is not located at part.transform.position ?
<discord-> e​gg. — I am not
<discord-> e​gg. — do any of those parts have a nonzero CoMoffset?
<discord-> D​RVeyl. — Yes.
<discord-> e​gg. — aha
<discord-> e​gg. — interesting
<discord-> e​gg. — which ones?
<discord-> D​RVeyl. — The recent build with procedural fairings. Uh, the boattail on that engine in the last video, looks like
<discord-> e​gg. — hm
<discord-> e​gg. — I wonder whether that is enough to explain the effect seen here though
<discord-> D​RVeyl. — Tho there is use of CoM shifting in various RO parts.
<discord-> D​RVeyl. — Not sure if in his video.
<discord-> e​gg. — yeah, it is known that I am ignoring that, but by and large my assumption is that the consequences are minor
<discord-> d​kavolis. — > I wonder whether that is enough to explain the effect seen here though
<discord-> d​kavolis. — @egg Without the boattail, the rocket goes straight up without spinning