<awang>
Question for anyone using MJ for timed launches:
<awang>
Does MJ take into account engine spool-up time?
<awang>
I could have sworn that at some point MJ did, so the launch clamps actually released at T-0
<Bornholio>
now way, it can't handle the 30s spool up on a nuke worth....
<awang>
But now, MJ ignites the engines at T-0
<awang>
And idk if I'm just remembering things incorrectly
<awang>
Bornholio: You're launching with nukes on your first stage?
<Bornholio>
I have, A Pheobus II with a Sea level nozzle would work fine if it stays below 2600C
<Bornholio>
Methane is preferable otherwise tankage is a bit too much and TWR is higher
<awang>
Wow
<awang>
What kind of delta-v do you get out of it?
<Bornholio>
Single Stage about 7k, usually use with a set of High ISP Solids to get it to orbit. Pretty good Payload mass fractions that way
<Bornholio>
Use a BNTR or Pewee on top to push to mars orbit.
<awang>
That's pretty darn good
<awang>
Man, it's really easy to forget the effect tankage has on delta-v
<awang>
Tried comparing HTP vs N2O for RCS
<awang>
If fuel is changed so the thrusters have ~15 minutes of burn time, HTP provides a bit more dv
<awang>
Somewhat counter-intuitive
<soundnfury>
awang: yay for density impulse ;)
<awang>
And not fun to calculate by hand :(
<Bornholio>
thats a lot of burn time
<awang>
soundnfury: I learned something!
<awang>
Bornholio: I like to overengineer :D
<awang>
And I'm trying to take a bit extra in case MJ wants to waste a ton of fuel
<soundnfury>
15min is reasonable for a probe that will be doing a lot of orbital manœuvres
<Bornholio>
I like lots of RCS myself, since it saves missions.
* soundnfury
wonders what Cassini's total burn time was
<awang>
It's only ~60 m/s in this particular case, so I don't think it's going to be saving missions
<Bornholio>
Technically not RCS for most of it
<Bornholio>
360 engine starts
<soundnfury>
Bornholio: I tend to lump RCS and small thrusters like the not-1kN together, since I often use (say) a pair of 120N RCS thrusters as a probe's main manœuvring engine
<awang>
I think I'm really feeling not having 1956/1957 solid motors
<awang>
Have to use an Aerobee for insertion, and I think I'm paying quite a mass penalty for that
<awang>
Maybe
<soundnfury>
awang: I find that XASR-1 is a _great_ kick stage engine
<soundnfury>
solids just don't compare IMO
<Bornholio>
IIRC Cassini used 3tons of fuel
<awang>
soundnfury: I was thinking that maybe density impulse would save the day again
<awang>
Apparently not?
<awang>
But yeah, using the XASR-1 right now
<awang>
Trying to build a lunar orbiter with 1956/1957 orbital tech and 60 tons
<soundnfury>
hmm, my first lunar orbiter this game needed a Thor-Agena (+ XASR-1 kick stage) and reached a pretty elliptical orbit (aposelene ~3500km)
<soundnfury>
if you can do it with 1957 engines I'll be impressed - the most I did with those was a lunar impactor (and that had Castor I boosters on its Thor-Able)
<awang>
I don't think I have the Agena upper stage
<awang>
And IIRC I couldn't use the LR-79 because it didn't have enough liftoff TWR
<Bornholio>
Cavea-B for the win at 60tons, one big RCS thruster for the main and 1kN Thrusters for TLI.
<awang>
Don't remember for sure
<awang>
I might be able to make orbit if I (ab)use Principia
<Bornholio>
I like the polar drop in orbit. Keep the impulse low and get a mapping orbit.
<awang>
Polar drop in orbit?
<Bornholio>
launch polar and then make your TLI from that, over shoot lunar orbit slightly and get a elliptical orbit with PE about far lunar equator. Good for getting all the biomes with minimal dV
<Bornholio>
little more dv and you can get a circ mapping orbit for radar/sar/optical mapping
<awang>
...That's a good idea
<Bornholio>
its not good for impactor combo's or returns of any kind
<awang>
Oh
<awang>
Not impacting my TLI stage might be a bit problematic
<Bornholio>
can still do it but then your orbit gets more elliptical unless you have the extra dv and burn to correct it
<awang>
Hmmm
<Bornholio>
I've done little sepatron slammers with good returns though
<awang>
Time for a lot of simulations, it looks like
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<wb99999999>
hey guys
<awang>
\o
<Bornholio>
Hey Seven.
<wb99999999>
how can I make a payload mount looks good?
<wb99999999>
hello born
<Bornholio>
the man rate intersage bottom.
<Bornholio>
interstage
<wb99999999>
it looks a little...bare
<wb99999999>
most payload attachment looks rather bare in my eyes
<wb99999999>
maybe I should strut my payload?
<Bornholio>
I strap the RCS tanks and other support do dads to it
<wb99999999>
good idea
<Bornholio>
the vens structural girder with the pip in the center looks good also, needs a spe point then
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<wb99999999>
will try it
<Bornholio>
also, try a conic proc tank full or empty with a baby sgt sep on it for a nice clean conic
<wb99999999>
I don't know if you do this or not
<wb99999999>
but I usually make the fairing a bit larger so it looks realistic
<wb99999999>
proc fairing auto fit would give me a stubby shell
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<awang>
soundnfury: Yeah, looks like I can't even make orbit as-is
<awang>
Going to have to wait for a later tech node :(
<awang>
btw, anyone know what delta-v is required for direct ascent?
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<soundnfury>
awang: direct ascent to what?
<awang>
Moon
<awang>
Sorry, should have been more specific
<awang>
I'm probably a few hundred m/s short of orbit
<awang>
Going to have to reduce payload to lunar orbit at least
<Bornholio>
tune the payload and waste ascent fuel
<awang>
Probably was a bit on the ambitious side
<awang>
Waste ascent fuel?
<Bornholio>
reduce your ascent fuel and tune both TLI and orbital burn, get on a free return path with a large lunar orbit and make a big barely captured ellipse
<Bornholio>
hard to do with aerobee engines :P single burn is painful
<awang>
I'll have to see how much I can shave off my payload
<awang>
That probe core is heavy :(
<awang>
Might look into ballistic captures, too
<awang>
That way I can ditch the probe core, which will save a lot of mass
<awang>
Still don't get what you mean by reduce ascent fuel :(
<awang>
Think I can cut the amount of fuel for the capture burn at least
<awang>
Current is for capture to ~100x100 km
<Bornholio>
make sure you are only boosting mass you use. What is your main engine?
<awang>
RD-107 first stage, X-405 second stage, X-405 TLI, XASR-1 capture
<Bornholio>
never fond of the 405
<awang>
It produced the lightest upper stages, so it's what I ended up using
<awang>
Highest upper stage ISP, too
<awang>
RD-107/RD-108 has even higher vacuum ISP, but can't exactly use those for an upper stage
<awang>
Why don't you like the X-405?
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<Bornholio>
not sure just always found a differnt way
<Bornholio>
probably 'cause vangaurd
<awang>
?
<Bornholio>
3 of 11 grapefruit launches succeeded
<awang>
Oh wait
<awang>
Just remembered that my TLI stage is an AJ10
<awang>
Changed it last minute, and forgot until now because I'm in a sim and the fairings were covering it up
<awang>
Oops
<Bornholio>
night and good luck lunaring
<awang>
Yep, 773 m/s short of orbit
<awang>
Got a lot of cutting down to do
<awang>
Attitude jets are actually pretty heavy o_O
<soundnfury>
awang: yeah you shouldn't need anything like as big as an XASR-1 for capture unless you need a low aposelene
<soundnfury>
at your stage I'd just go for a highly elliptical lunar orbit, which only needs a few hundred m/s for capture
<soundnfury>
which then means you should be able to make the probe light enough for an XASR-1 TLI stage
<soundnfury>
and suddenly your required mass-to-LEO is waay lower :)
<awang>
soundnfury: Wellllll
<awang>
I'm aiming for ambitious on the first try
<awang>
Partially because my computer is old, and I'm running Principia, so the fewer vessels I can launch the better
<awang>
So trying to go for low orbit to grab pretty much everything in one go
<awang>
Although idk if lunar perturbations will have anything to say about that
<awang>
I think I solved the mass problem
<awang>
Got rid of the level 2 camera, and I think I have enough dv to make it to orbit
<awang>
Barely
<awang>
In theory I could get it lower if upper stage avionics mass limits could go lower than 3 tons
<awang>
But nooo
<awang>
Also, gotta walk back home
<awang>
So brb
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<awang>
Ideally I'd get a lunar orbit that has its periapsis right at the equator and pretty elliptical so I can get both high and low science for all biomes
<awang>
I doubt I can hit that accurately though
<soundnfury>
awang: heh, I did something similar in Earth orbit for a recent science sat
<soundnfury>
60×13Mm, orbital period 1 day 32 minutes, apsides near the equator.
<soundnfury>
only trouble is, I launched from the Cape, so inclination was only 60° - no poles or tundra
<awang>
Also, why does rocket engine thrust seem to oscillate around the rated thrust?
<soundnfury>
there's a bit of Perlin noise added in
<awang>
soundnfury: How'd you pull off that launch?
<awang>
Long coast period, with the orbital insertion burn on the far side of the Earth from the Cape?
<awang>
And shouldn't you be able to get a polar orbit from the Cape?
<awang>
Or are you playing realistic with launch corridors and such?
<soundnfury>
observing launch corridors
<soundnfury>
launch 036° from the Cape, reach 55° parking orbit. Coast half an orbit
<soundnfury>
then relight the Agena D to boost to 60Mm apogee. Coast another half orbit, and use the satellite's thrusters to raise apogee
<awang>
Is the Perlin noise from RO/RF?
<awang>
Ah, I see
<soundnfury>
probably RF, yeah
<awang>
Not going for a polar launch from Vandenberg?
<awang>
Wasn't someone here working on a range safety mod that incorporated launch corridors?
<soundnfury>
I don't have very much build capacity at Vandy, so I only go there when I need to.
<awang>
Ah
<awang>
Fair enough
<awang>
Hmmm
<awang>
Is it possible to use the VAB to build something somewhere, and launch from somewhere else?
<soundnfury>
awang: yes, but it's cheating
<awang>
Oh
<awang>
Didn't even know it was possible
<awang>
Thought KCT would have kept track of vehicles per-site or something
<soundnfury>
roll it out, switch KSC, recover using the KCT GUI (*not* the 'Recover' button at top of screen)
<awang>
Oh
<awang>
Yeah, that sounds expoit-ish
<soundnfury>
however, in RP-1 that means paying the rollout costs twice, which I guess makes it slightly less cheaty
<soundnfury>
right, zzz for me. nn & hf
<awang>
Oh right
<awang>
nn?
<awang>
Night!
<awang>
Question for anyone still on:
<awang>
How quickly is ullage supposed to take effect after engine shutdown?
<awang>
I can get away with not putting ullage rockets on my second stage
<awang>
but I'd like to know how un-realistic this is before continuing doing this
<lamont>
hotstage
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<lamont>
frikkin swizzlespace trolls me again
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<lamont>
and radians trolled me
<lamont>
and world space vs body centric coordinates trolled me
<ProjectThoth>
Swizzlespace?
<lamont>
the Orbit class is right handed, while the rest of KSP is left handed so you have to transpose y and z converting to/from the Orbit class
<taniwha>
I briefly considered fixing that, but it would have been too wide-sweeping a change to risk the breakage (and there wasn't the time for such)
<taniwha>
Also, left-handed systems make me twitch :P
<lamont>
well its sensible once you figure it out
<taniwha>
yeah
<taniwha>
well, most physics books are right-handed
<taniwha>
and certainly 3d vector math texts
<lamont>
right so someone plagiarized the guts of the Orbit class and that’d be easier to do right-handed
<lamont>
then the solution of how to bolt it onto Unity with left-handed everything else was swizzlespace
<taniwha>
yeah
<taniwha>
that someone was HarvesteR, of course :)
<taniwha>
Meanwhile, I would have figured out how to get Unity to be entirely right-handed :)
<lamont>
got the game off of the ground
<taniwha>
Indeed he did
<taniwha>
(not sure about PhysX, nor DirectX, but OpenGL lets you specify which one you want (set your VP matrix and your triangle winding direction correctly)
<lamont>
actually ran across a real trajectory algorithm where they mention in passing that there is a singularity in dealing with zero inclination orbits and the solution is to swap coordinates and turn it into a 90 degree inclination problem and back
<ProjectThoth>
Was the SPS ever used to aid in descent to the Moon, unrelated question.
<taniwha>
lamont: that's one solution, yeah, though you're still left with the singularity that pops up for 0 eccentricity
<taniwha>
(where's the periapsis?:)
<lamont>
i’m not sure this algorithm has that singularity
<taniwha>
not all do
<taniwha>
solving for the closest point on the trajectory does, though (quartic solvers don't like being fed quadratics:)
<taniwha>
however, that's actually the only singularity when you use polar coordinates
<taniwha>
well, that and trying to find the closest point on a circle when at the circle's center
<lamont>
and even if you say “pick the celestial easternmost point” based on some arbitrary universal prime meridian some jerk is gonna hand you a circle that is all north-by-west
<taniwha>
yeah
<taniwha>
eg, a north-by-west ellipse collapsing to a circle
<taniwha>
(though KSP will snap the ArgPe for that)
<lamont>
the bouncy ArgPe’s were amusing
<lamont>
and it may have just wired up PEG to MechJeb’s node executor
<lamont>
mic… dropped…
<lamont>
'niter
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<wb99999999>
lamont r u still here?
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<awang>
Well, got to orbit with 80 m/s to spare
<awang>
Now time to see if 3157 m/s is enough for TLI with a relative inclination of ~35 degrees
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<awang>
lamont: I guess hot staging would work, but the interstage looks ugly :(
<awang>
Even if I could hot stage, aren't you generally required to hot stage while the first stage is still running?
<awang>
I guess the ullage question also applies to my TLI stage
<awang>
Fuel seems to be stable after over 20 minutes in orbit
<awang>
Stability also tends to go down during timewarp, but goes right back up when warping ends
<awang>
lamont: How do I get PEG to go back to a heading of 90 after selecting a target in map view?
<awang>
I want to get the timed launch, but I'd prefer not to have PEG execute such an extreme dogleg to match inclinations with the moon
<awang>
Also, PEG seems to want a pitch of 6.8 degrees for launching to a 185x185 parking orbit?
<awang>
It definitely started out at 50something degrees earlier
<awang>
And the stage analysis isn't showing up again after hitting "Reset PEG"
<awang>
Reverted to launch, and pitch is back to 57.6
<awang>
idk what happened there
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<BadRocketsCo>
Howdy
<awang>
And now the PEG stage stats aren't updating o_O
<awang>
\o
<awang>
Uhhhh
<awang>
lamont: Now I'm seeing "Autopilot status: Pitch program -6.25 degrees"
<awang>
What did I break
<BadRocketsCo>
awang: btw can you tell me a bit more accurately which boat tail part you meant?
<BadRocketsCo>
As if in I can't find what you think
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<awang>
BadRocketsCo: It looks exactly like the flat interstage adapter
<awang>
I'll get a screenshot when KSP finishes booting
<BadRocketsCo>
Aight
<awang>
I think it's actually a duplicate of the flat interstage adapter
<awang>
It's just lighter
<awang>
Yep
<awang>
Should be there if you have proc fairings
<BadRocketsCo>
Oh, is it like a duplicate of a stock part? I may have those deleted
<awang>
It's a duplicate of a proc fairings part
<awang>
Proc fairings the mod
<awang>
Not stock fairings
<awang>
Uhhh
<awang>
I just realized
<awang>
Are you playing from dev?
<awang>
Or the v11.5.1 release?
<awang>
Seems it's something added after the last official release
<BadRocketsCo>
Oh, I'm still in 1.2.2
<BadRocketsCo>
Like, KSP version
<awang>
I think dev is built for 1.2.2
<BadRocketsCo>
Hmm
<awang>
Even then, you could always just grab the MM configs and skip the other stuff
<BadRocketsCo>
I play RP0 too so maybe that loses some parts or something
<awang>
I have RP-0 too, and the boattail adapter is there
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<lamont>
awang: yeah i’ve hit pitch program: -x.y degrees and don’t know what that bug is caused by
<awang>
At least for me it looked like the PEG UI wasn't updating when that happened, if that helps
<lamont>
yeah if you button mash on the ascent guidance window between launch to target and enable autopilot you can wind up with the autopilot enabled, but peg disabled somehow
<awang>
Hmmm
egg|afk|egg is now known as egg
<awang>
Don't remember exactly what I did to break things
UmbralRaptor is now known as NomalRaptor
<awang>
But I'm inclined to think that it didn't involve rapid clicking
<lamont>
it doesn’t require rapid clicking, but you have to setup your launch-to-target first and then enable the autopilot, and disable it in the reverse order
<lamont>
if you don’t it gets confused
<lamont>
unfortunately that’s the least of my worries right now
<awang>
Oh
<awang>
Might have been the disabling it that caused it then
<awang>
Since I was trying to see if I could convince PEG to launch with a heading of 90 degrees after warping to launch for the right inclination
<lamont>
and IDK what to tell you about the moon other than PEG doesn’t support principia yet
<lamont>
yeah i think its just broken for that
<awang>
I mean, I'm not asking for Principia support
<awang>
Or at least I don't think I am
<lamont>
well its broken for targetting inclinations which are relatively far below the launch latitude which is principia-driven concern
<awang>
I guess a non-Principia example might be selecting a target in the map view, but manually setting a different inclination
<lamont>
which only realy comes up in principia trying to work around the launch latitude problem
<lamont>
better thrust integrals would help a lot i think
<awang>
I don't even have to try to launch into the Moon's plane
<awang>
If I just target the Moon, PEG sets its heading to 157 or thereabouts
<awang>
Even if I end up not wanting to launch into the Moon's plane
<lamont>
right, but why would you target the moon if you don’t want to launch into its plane or to rendezvous?
<egg>
lamont: wait why does principia change the inclinations you target
<lamont>
principia wobbles the moon’s inclination over time
<egg>
well the inclination not much
<egg>
it precesses it a lot, but the inclination should be somewhat stable I think?
<lamont>
PEG has no troubles when its at -0.25 to KSC, but when its -5 to KSC then its a problem
<lamont>
^ we’re seeing roughly that
<awang>
lamont: idk, good question
<egg>
uh
<egg>
ah in the equatorial frame right
<egg>
hm
<awang>
Right now, the use case is working around PEG
<egg>
no wait I'm confused still
<awang>
Time the launch, but launch due east anyways
<egg>
NomalRaptor: does the inclination of the moon in the equator frame change significantly?
<awang>
I have to target the Moon to use the rendezvous planner's relative inclination functionality
<awang>
Launch when the relative inclination is minimized
<NomalRaptor>
egg: I want to say yes. 10s of degrees.
<egg>
ah ok
<awang>
egg: IIRC the Moon's inclination relative to the equator oscillates between ~28 and ~18 degrees over a ~18 year period
* egg
bad at visualizing those things evidently :-\
<lamont>
“A google search has revealed that the Moon's inclination is between 18.29° and 28.58° to the Earth's equator.”
<lamont>
RSS pins it at 28.58 i guess, which is the kindest number to use, but Principia wobbles it more accurately
* egg
wobbles at awang
<lamont>
actually its slightly under that, 28.35-ish i think
<awang>
lamont: I guess another problem might be that when launching to the Moon's plane, the orbital inclination shown in the ascent guidance window doesn't match what PEG is actually trying to target
<lamont>
yeah that’s cosmetic
* NomalRaptor
nutates.
<lamont>
someone tried to fix PEG for low launch inclinations before it could support yaw steering and that was the result
<lamont>
the “iy inc” field in the PEG display is what PEG is actually doing
<awang>
Ah
<awang>
Yeah, that number makes a lot more sense
<lamont>
yeah when you’ve got a target set, PEG ignores the orbit inclination field entirely
<awang>
Ah ha, think I found how to get around the PEG heading thing
<awang>
Just unselect the Moon as a target
<awang>
...I feel stupid now
<awang>
Jeez TestFlight likes to kill Saturn V launches
<lamont>
awang: for the launch-to-target-plane option i’m finding ‘1’ put into the field works well for this vessel and a 90 degree orbit
<awang>
Does launch to target plane not work well with 90 degree target orbits?
<awang>
I've never tried
<lamont>
it works fine, but you want to lanch slightly before the target plane or else PEG wiggles a bunch to hit exactly that target plane
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<awang>
Oh, is the field for how much lead time you want to have?
<lamont>
lead angle
<lamont>
yes
<awang>
Ah
<awang>
How much wiggle are you talking about?
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<lamont>
probably worth a couple hundred dV or so
<awang>
Also, how difficult do you think adding "pitchover + follow prograde" for in-atmo flight prior to PEG taking over would be?
<awang>
Oh wow
<awang>
That's a lot of waste
<awang>
Why does it do that?
<lamont>
it does *exactly* what you tell it to
<lamont>
if you target a specific 90 degree orbit, and then launch when you are exactly in the plane of that orbit, PEG will wiggle its way up to exactly that orbital plane
<lamont>
if you lead the launch by a degree, then it doesn’t have to fight that hard to zero the coriolis velocity
<awang>
Hm
<awang>
So without the lead angle, PEG tries to zero the "horizontal" velocity, overshoots, tries to zero it in the other direction, overshoots, and repeats?
<lamont>
no, its optimal
<lamont>
it needs to burn west hard to try to zero the coriolis velocity, but in the time it takes to zero the coriolis velocity it will have slid to the east of the target orbit, so will have to overshoot a bit back to west, then that westwards velocity will need to be cancelled precisely when the burn ends
<awang>
Ohhhh
<awang>
That makes a lot more sense
<awang>
Thanks for the explanation!
<lamont>
there is a precise answer to “how much do i need to lead the launch time, for this rocket, to hit this orbital inclination, to use the least amount of delta-V” but PEG isn’t that kind of program
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<awang>
Another job for external solvers?
<awang>
Uhhhhh
<awang>
I'm seeing very large pitch oscillations near Saturn V third stage burnout
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<awang>
±45-50 degrees
<lamont>
probably crappy thrust integrals
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<awang>
Hmmm
<awang>
This second launch I'm not getting the same kind of pitch oscillations
<awang>
But MJ just doesn't cut off the engine at the right time
<awang>
Targeted 185km x 185km, currently at 185km x 1.5Mm and still burning
<awang>
Guidance stopped a while ago though
<lamont>
ehm that’s wrong
<lamont>
there was a bug like that which i fixed
<awang>
I'm on the mchenry2 tag
<lamont>
PEG was disabling itself at tgo < physics update but then the ascent module was hammering on it with peg.enable every tick
<lamont>
that has AssertStart()
<lamont>
so lcg/PEGAS2 HEAD should have a fixed NodeExecutor
<lamont>
i just pushed mchenry3 for you
<awang>
So PEG was being switched on/off alternately every tick?
<awang>
Is that still a problem?
<lamont>
the major gotcha that i know of is that you need to include some lead time in planning maneuver nodes, if you do “right now” then it’ll be weird
<lamont>
no
<lamont>
and it wasn’t
<awang>
Ah, ok
<awang>
I held off on updating since I wasn't sure if you had reached a fix point
<awang>
How much lead time is "some" lead time?
<awang>
About?
<awang>
Few seconds?
<awang>
A minute?
<lamont>
the problem was that hammering on `peg.enabled` enables if its disabled — but for PEG to control disabling itself, then other modules can’t hammer on that, or else the next peg.enabled call someone else does re-enables it after PEG disables itself. so i had to create AssertStart() for other modules to hammer on and won’t override PEG distabling itself.
<lamont>
it needs to be able to slew around to the node
<lamont>
if you don’t include any lead time then it immediately fires in whatever direction you are pointing
<lamont>
so however long it takes to rotate your vehicle around
<awang>
Ah, fair enough
<lamont>
obvious fix is fairly obvious, but i haven’t dug into it yet
<awang>
The AssertStart fix makes sense
<awang>
Although it seems something still isn't quite right, since PEG is disabled without killing throttle?
<lamont>
it shouldn’t
<awang>
Interestingly, I only saw that behavior with the RO Saturn V
<lamont>
peg itself calls Done() which clears users and throttles down, nothing else should be disabling it
<awang>
My career launchers don't seem to be having any issues
<lamont>
maybe mchenry2 is buggy and i’ve just forgotten i fixed something
<awang>
Thing is I've been using mchenry2 ever since you tagged it
<awang>
The missing cutoff only showed up today
<awang>
When I was doing sandbox launches to try to figure out another performance issue
<lamont>
the other possibility is that peg has lost its solution because of something to do with stage separation close to burn termination time
<awang>
The previous staging event was ~2 minutes prior to cutoff
<awang>
I did have to limit autostaging to that stage specifically because MJ would continue autostaging for a few more stages, activating the SPS engine and detaching the petal fairings
<lamont>
if you’ve got a very low TWR upper stage comared to booster burnout TWR that could be the problem
<lamont>
PEGs thrust integrals still loft too high with the booster
<awang>
IIRC third stage TWR started at 0.60 and ended at 1.something
<awang>
Yeah, I noticed that
<lamont>
i either need someone to find me that shuttle memo, or i need to crack using the jaggers thrust integrals in a way that is stable, or i just need to replace it with a runge-kutta integrator
<awang>
Shuttle memo?
<lamont>
my space stackexchange post
<awang>
I see
<awang>
Contacting them didn't pan out?
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<wb99999999>
heyllo
<soundnfury>
ohai nines
<awang>
lamont: git is telling me you tagged mchenry3 at the same place as mchenry2
<awang>
Was that intentional?
<lamont>
fuck no
<lamont>
okay should be fixed now
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<awang>
lamont: Push?
<lamont>
its pushed
<lamont>
“git pull —tags”? (double dash, not unicode em-dash)
<awang>
Ah
<awang>
I was using git fetch
<awang>
Didn't know that I needed the --tags flag
<awang>
There we go
<lamont>
i don’t think you do unless someone rewrites history like i just did
<soundnfury>
awang: heya, I'm trying to merge in and test a bunch of your PRs in one go. Currently struggling with a crashing MonoDevelop though :(
<awang>
lamont: Didn't know that I needed --tags when fetching rewritten tags either, then
<awang>
soundnfury: Glad to hear the news!
<awang>
Hopefully it's not my PRs causing the crashes?
<awang>
Something in KSP is leaking memory like a sieve
<awang>
I get a few hundred megabytes additional RAM consumed per revert to launch
<soundnfury>
awang: nope, monodevelop is just a pile of shite
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<awang>
Also, what's the difference between "physics delta" and "max delta time"?
<awang>
soundnfury: Agreed there. I literally can't even open monodevelop on my machine
<soundnfury>
I mean, it's written in a frigging managed language, how TF does it crash with a malloc "double free or corruption"? -_-
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<awang>
Magic, evidently
<soundnfury>
nah, if it were *magic* it'd be written in *python*.
<soundnfury>
(or possibly Lisp, so I hear)
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<awang>
lamont: Yeah, MJ isn't cutting throttle any more
<lamont>
it does for me
<lamont>
i haven’t seen it not cutting throttle since i put that fix it
<wb99999999>
OMG I got my hand on a bunch of data on Chinese rocket engines
<wb99999999>
fairly detailed
<awang>
soundnfury: Yeah, looks like I'm going to have to aim for a high lunar orbit. Can't get the delta-v needed to account for the plane change
<awang>
On the other hand, looks like lunar perturbations may let me get pretty close
<awang>
Wait
<awang>
Crap
<awang>
Forgot about the impacting part
<awang>
That could be problematic
<awang>
lamont: I'll just wipe my MJ data and see what happens
<awang>
I assume it's something on my end, since it used to work
<awang>
Also, now that I think about it
<awang>
A drop-in polar orbit sounds pretty complex to plan...
<soundnfury>
awang: ehhh, it's not that hard in patchy conics with konrad, and AIUI principia's manœuvre planner is effectively similar to konrad's
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<soundnfury>
then again, I don't know just how meltybrain principia really is (mumble mumble square orbits)
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<lamont>
if you’re just trying to do a free-return around the moon patchy conics is close enough to actual n-body
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<soundnfury>
lamont: yeah, but for getting to polar the errors are much more significant
<lamont>
battin has an algorithm in his book to plan free-return trajectories with periapsis and inclination control around the lunar orbit, along with inclination control of the return approach to earth which is based on patched conics, and he says it gets very close
<soundnfury>
IME the inclination is really rather sensitive
<lamont>
he’s also got an algorithm that you can feed the patched conic solution into in order to get the proper n-body trajectory
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<awang>
soundnfury: I'm more worried about making sure that the LAN is in the right place
<awang>
That and I don't know whether I have enough dv for a polar orbit
<soundnfury>
uhh, are you trying to get _to_ lunar polar, or just to lunar _from_ earth polar?
<awang>
I had to cut back on batteries, too, since my TLI stage needs more dv to account for the inclination difference
<awang>
Ideally, to lunar polar
<awang>
Bornholio suggested going to lunar polar from Earth polar
<soundnfury>
the former can be done with just a degree or so of relative inclination (as long as the arg-pe is roughly ±π/2)
<awang>
Minimum relative inclination I can get right now is ~4.5 degrees...
<soundnfury>
in that case, you want to use a different arg-pe that puts the node closer to the encounter