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<Starwaster> awang: while (count-- > 0) {
<Starwaster> this.convectiveTotal += vessel.Parts [count].thermalConvectionFlux * this.dTime;
<Starwaster> WELL alrighty, nothing REALLY wrong with the DRE 2.5m heat shield and nothing really changed in thermal either. Just the stock Kerbin 7x convective multiplier... I don't often play stock Kerbin so I didn't notice a problem with that part
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<awang> Starwaster: Ah, didn't know that it helps with rotation but not translation
<awang> That's somewhat annoying
<awang> And what's the code for?
<awang> Total convective heating per unit time?
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<KevinStarwaster> awang correct, for the entire vehicle. take out dtime if you just want wattage. (it's the delta time)
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<awang> Starwaster: Why are you giving me this code?
<awang> I feel like I'm missing some context, and looking through scollback isn't jogging my memory
<awang> Sorry for being so obtuse
<awang> lamont: I'm still seeing NREs from MechJebModulePEGController.DrawCSE
<awang> When I'm in the SPH
<lamont> weird
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:24:38]: "Alright, tried mchenry5 with a launch to 185km x 185km, inclination -63.4"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:25:04]: "Running update interval of 0.01s"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:25:57]: "Got some pitch oscillations as PEG approached terminal guidance. Seemed to get worse at a rapidly increasing pace as PEG got closer to terminal guidance"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:26:35]: "i.e. oscillations stayed between ~13 degrees and ~17 degrees, changing slowly enough that the upper stage could keep up, until maybe around 10 seconds before terminal guidance"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:27:11]: "Around 2 seconds before terminal guidance pitch was changing at over 10 degrees/sec"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:27:32]: "Right when terminal guidance started, vgo changed from ~200 m/s to ~2570 m/s"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:27:56]: "and vgo is *increasing*"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:28:13]: "pitch seems to have stopped changing as fast"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:29:22]: "vgo continued increasing during the entirety of terminal guidance, ending at ~2700 m/s"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:29:57]: "Final orbit was 182.846km x 215.110km. Upper stage burned out at TWR of 2.33"
<Qboid> lamont: awang left a message for you in #RO [09.12.2017 05:40:55]: "Should probably mention that PEG status was either CONVERGED or TERMINAL. Didn't see anything wrong at any point."
<Qboid> lamont: acharles left a message for you in #RO [09.12.2017 10:43:16]: "I think I found the issue. I had staging setup such that I would hot stage the verniers on the blok i, then I would separate and then stage the engine on, which meant that MechJeb thought that the stage was going to take 13 hours, instead of realizing that I’d eventually turn on the other engine."
<lamont> whoah
<lamont> and yeah, i’ve been seeing odd oscillations i don’t quite understand. one thing that would be useful would be to know if they only happen when the LAN is free or if it also happens when targetting a particular orbit
<awang> I'll try launching from Kourou, targeting the Moon's orbit and see what happens
<awang> Last Saturn V launch from the Cape didn't even make orbit due to those oscillations :(
<awang> Any idea why vgo would increase during terminal guidance?
<lamont> it doesn’t matter in terminal guidance
<lamont> that’s just terminal guidance oscillations
<lamont> in terminal guidance all that gets used is tgo, lambda, lambdaDot and t_lambda/K
<awang> Ah
<awang> One less thing to worry about
<lamont> but the usual qualifications apply — PEG has to know what you’re going to do (like acharles found out there, if you stage thing or enable disabled engines you can cause severe issues), and it behaves a lot better if you’re not dropping stages near burnout, and you need to be able to hit your orbit on a single burn (it needs to both be long enough, yet you also need enough TWR in the lower stages to huck it up there)
<awang> How much margin is there for "near burnout"?
<awang> If it's too long I'll need to use something other than a Saturn V
<lamont> i don’t actually know
<lamont> generally i’ve seen things start to go a bit wonky with phi increasing before stage separation when that’s a problem — that’s a hint that the upcoming decelerating thrust profile is giving PEG prediction issues
<lamont> and its likely all made worse by the thrust integrals lofting rockets too high
<awang> What is phi supposed to indicate?
<awang> And that reminds me, I should get around to sending Draper lab a note
<lamont> linear tangent steering doesn’t point the rocket in one direction and go. there’s a central direction which is lambda, but steering sweeps through that direction. you start phi degrees off lambda in the lambdaDot direction and sweep to - phi.
<lamont> phi generally starts out large, and is clipped to an upper bound of 45 degrees, and should get smaller
<lamont> if its gets larger, that’s usually a sign something is starting to go wrong
<awang> Ah
<awang> Makes sense
<awang> Actually
<awang> Why the sweep?
<lamont> its provably optimal by math
<lamont> yeah so the saturn used the S-IVB third stage for orbital insertion
<lamont> i’m guessing the second stage lofts it too high and then the staging discontinuity causes issues
<awang> Is PEG really only for two stages to orbit?
<lamont> no
<lamont> its just these thrust integrals are insufficient
<awang> I see
<awang> Should I be using a different rocket to test pitch oscillations if LAN is a free variable?
<lamont> i may attempt to replace them with rkf45 numerical integration and see what happens, but that might also lead to instability IDK
<awang> That sounds pretty labor-intensive
<lamont> the thing to do is to try to launch your rocket to the moon in normal non-principia RSS
<awang> Would launching from Kourou work?
<lamont> at some point i think i want that anyway, because rkf45 hooked up to a newtonian solver gives real calculus-of-variations based trajectory optimization
<lamont> IDK
<awang> Since the latitude is low enough that inclinations shouldn't be an issue
<lamont> oh yes, Kourou right
<lamont> 5N that’s wonderful, yes use that
<lamont> launch to plane of target to the moon
<awang> Alright, give me a bit
<lamont> if it works with the plane locked then its the code that allows the LAN to be free that is causing issues
<lamont> i’m heading to bed
<lamont> so i’ll check tomorrow
<awang> Alright
<awang> Night!
<awang> ferram4: Are you familiar with how KSP calculates thermal fluxes?
<awang> Starwaster pointed out that the code I added to calculate free molecular aerothermal flux produces fluxes that are pretty different from those returned by KSP
<awang> And I'm curious why
<awang> Wondering if they're actually measuring the same thing
<awang> And if so, why the results are so different
<awang> Er, *code I added to MJ
<awang> lamont: When launching to the plane of the Moon, got no pitch oscillations, and a beautiful 186.660 x 182.821 orbit
<lamont> ahh, its the free lan stuff then
<lamont> i’m not too surprised, i kind of spliced that in without really understanding what it does
<lamont> i’m trying to fix the node executor to be accurate right now, i’m probably going to circle back on that stuff next
<awang> I'm running a second launch just to make sure, but yeah, looks like it
<ferram4> awang, depending on how simple or complicated your code or KSP's might be, it's possible for them to be off by a bit. Are they multiple order-of-magnitude off?
<awang> ferram4: Yeah, looks like it's pretty far off
<awang> I'm just calculating flux as 1/2 * rho * v^3
<awang> Er
<awang> Pretty far off in the case of RSS/RealHeat/Deadly Reentry
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<awang> Stock seems to be off by roughly a factor of 3.5?
<ferram4> So not by an order of magnitude.
<awang> Not in stock
<ferram4> Then it's likely whatever constants are being used to tweak it.
<ferram4> And so for stock it's probably good enough.
<awang> RSS is off by one or two order of magnitudes
<awang> At least for one data point, in stock MJ said 26.54 kW/m^2, KSP said 93.36 kW/m^2
<awang> Altitude 66.76km, velocity 2268.3 m/s, during descent
<awang> RSS, during ascent MJ says 3.930 kW/m^2, KSP says 64.96 W/m^2
<awang> 101.003km, 2488.4 m/s
<Qboid> [fd321] title: Add freeMolecularAerothermalFlux to VesselState... by Alex Wang | Additions: 3 | Deletions: 0 | https://github.com/MuMech/MechJeb2/commit/fd321552c246af53060cb46c9950c7422092f903
<ferram4> FWIW, stock has very different values for its scaling.
<awang> 1/2 * rho * v^3 probably isn't the right equation to use there, then?
<ferram4> Considering that stock needs heating that is actually scary compared to the minor effects that it is in reality at those speeds.
<ferram4> Check what RealHeat does, it might just be the effects of the scaling constants.
<awang> That's true
<awang> To be honest, I'm really not sure what's going on in the RealHeat code
<awang> Seems it overrides MFI stuff
<awang> And I don't see constants, at least after a really quick glance
<awang> lamont: So I tried a launch where I used launch to target plane, but basically un-targeted right before the vehicle took off
<awang> Didn't get any pitch oscillations
<awang> un-targeted and aborted launch to target plane
<awang> Kept autopilot on though
<awang> Tried yet another launch, this time launching to the same inclination without targeting the body at all
<awang> Definitely see the pitch oscillations
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<Starwaster> lamont I decided to try your latest shuttle PEG build with a Saturn V-alike, 190km target orbit got me a 214x174
<lamont> Saturn V may have issues
<lamont> the suborbital third stage light to insertion gives the thrust integrals in that code issues, plus awang found the free lan code (if you’re not launching-to-target-plane) may be buggy
<lamont> also beware that the node executor has been replaced with PEG and i’m in the process of debugging that for accuracy right now
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* egg|zzz|egg stares at backlog
<egg|zzz|egg> there was a transient diomedea!?
<acharles> Did anyone else notice that MJ still does a roll program during PEG vertical ascent even if the force roll option is off?
<lamont> do you have the KosAttitudeController or HybridController turned on in Attitude Adjustment and does the roll go away if you select MJAttitudeController?
<lamont> (although i think this bug got reported on the forums and has been there since before sarbian messed around with the PIDs)
<acharles> I don’t know what those are. :P
<lamont> Attitude Adjustment Menu
<acharles> But I’ll check later.
<Starwaster> those are little creatures taht sit int here and they move the contro9l surfaces around
<Starwaster> Peter, Ivan and David... (PID)
<lamont> PID gremlins yes
<Starwaster> o.O
<acharles> Yeah, I know what a PID is, but I’ve never messed with MJ’s PID settings.
<acharles> So, I assume they are default.
<lamont> Starwaster: i made an attempt at fixing corrective steering
<Starwaster> yeah it seems to behave more ilke how it used to
<lamont> its in my branch and actually been merged
<lamont> yeah
<lamont> i never used it before so i’m not sure how well it works now
<Starwaster> hmmmm should that be turned OFF for PEG? Probably should given that PEG or any IGM inherently tries to correct itself?
<lamont> it doesn’t get invoked unless you’re in classic ascent profile
<Starwaster> well when It ried it with classic mode it worked well up until the final stages of ascent and then it started deviating, ascent angle ended up higher than it should have been by 10s of degrees
<lamont> so does it need to correct by burning down harder?
<lamont> there’s this +/- 30 degree clamp here: https://github.com/MuMech/MechJeb2/blob/dev/MechJeb2/MechJebModuleAscentClassic.cs#L188 that could be made wider
<Starwaster> I'll have to look at it later and get back to you
<lamont> but i don’t think that was actually doing what the code suggested
<acharles> I like comments until they conflict with the code, as written. And then I just get sad.
<lamont> yeah actually looking at that code another time what is going on there is that you’re controlling the offset via the length of the opposite site of a triangle, and the desiredThrustVector is the adjacent side. so the comment about 10 degrees i think is just nonsense. i might be able to copy the behavior of the old code better though.
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<awang> Anyone here get NREs when trying to show additional B9 proc wing data?
<awang> Stuff like wing area, chord length, etc.
<awang> Interestingly, RT is in the stack trace
<awang> NRE at WingProcedural.WingProcedural.InfoToggleEvent
<awang> Called from BaseEvent.Invoke
<awang> Called from RemoteTech.Modules.ModuleSPU.InvokeEvent
<awang> Called from RemoteTech.FlightComputer.UIPartActionMenuPatcher+EventWrapper.Invoke
<awang> ...Why is RT even there
<awang> I'm in the SPH
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<awang> Also, the sooner that stupid kerbals-add-mass-to-every-part bug gets stabbed the better
<awang> And just making sure
<awang> The slope of the Cm line in the FAR editor GUI indicates how stable your plane is?
<awang> The steeper the slope, the faster the plane will return to neutral?
<ProjectThoth> Is a telescoping interstage possible in the real world?
<awang> Telescoping interstage?
<ProjectThoth> awang: Yeah, for reuse purposes.
<ProjectThoth> It would just telescope to give the first stage a clean separation plane and reduce the length of the second stage.
<ProjectThoth> And, obviously, wouldn't be moved under load.
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<awang> Ah
<awang> idk then
<Bornholio> not sure about telescoping but dual plane seperation is a thing, also disintegrating insterstages
<ProjectThoth> I'm studying a reusable TSTO, for what it's worth - VTHL on the first stage, VTVL on the second.
<ProjectThoth> The best solution I've found for this, so far, is to use a robotic manipulator and stuff it in the payload volume for reentry/landing.
<ProjectThoth> Bornholio: I wanna bring it back, though.
<Bornholio> petal adapter
<ProjectThoth> Nosecone issues on reentry.