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Space Shuttle - Bugfixes

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Re: Space Shuttle - Bugfixes

Postby Thorsten » Thu Dec 26, 2019 6:28 pm

but I though the +2 would be able to circularize.


No, circularization isn't the goal, it wouldn't do that.

For BFS, that means OMS burns are done in manual attitude control, I've never tried that before but that sounds quite interesting


You still have rate-controlled DAP - so you just fly the ADI needles, center controls when they're good and that's all there is to it.
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Re: Space Shuttle - Bugfixes

Postby GinGin » Fri Dec 27, 2019 10:51 am

- Upon reaching orbit in the abort mode ATO, I've never succeeded to use the ITEM+35 +1 or +2 to program an OMS-1 or OMS-2 burn, it loads like a burn with 0 velocity. Maybe it has to be defined in the mission file?


It was mission specific.
I loaded target for ATO ( aiming for 105 Nm Apogee) or AOA target ( Locations KSC or white sands, shallow one or not for example etc)

For AOA, you can use target that you can find in ascent fdf part 7-1 ( you can see the little number after the slash, which would correspond to item35 + that specified target in real life)

You can feed leo tools with those peg 4 parameters ( and usually you will have to file with the Theta angle because our more lofted orbit shape will not be exactly the same than the one used in those files)

Image



I spoke a bit about it there

https://forum.flightgear.org/viewtopic.php?f=19&t=34315






- In a few situations, I was badly choosing to fly a TAL abort but finally ended in orbit. In that situation, I was never able to get the DAP to go back to OPS 104, it seems to get locked in Aerojet mode trying to get into attitude for the TAL reentry, with the FWD RCS switch-off forever.





If you fly a late TAL, the AP will probably - as you saw - put you on Orbit as you have enough propellant to be past 25kft Vi and in a standard insertion profile.

You can still ( it is what I do) order a manual cutoff when you have the speed to reach the correct TAL site that you choose ( like for a late TAL due to equipment failure for example)
You got the inertial speed there for a 51° orbit launch

Manual MECO before what would have done the AP

Image
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Re: Space Shuttle - Bugfixes

Postby eatdirt » Fri Dec 27, 2019 1:31 pm

Thanks Gingin, very detailed and helpful, as usual!
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Re: Space Shuttle - Bugfixes

Postby GinGin » Fri Dec 27, 2019 7:18 pm

Perfect :)
By the way , did you received my private messages?
I still got them in my outbox, weird.
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Re: Space Shuttle - Bugfixes

Postby eatdirt » Fri Dec 27, 2019 10:16 pm

Sorry, I've found them, they are there, thanks a lot for the material!!
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Re: Space Shuttle - Bugfixes

Postby GinGin » Mon Dec 30, 2019 3:49 pm

eatdirt wrote in Fri Dec 27, 2019 10:16 pm:Sorry, I've found them, they are there, thanks a lot for the material!!



Perfect :)



@Thorsten: I was playing a lot with GPC lately
A few feedback on one or two minor stuffs concerning Spec 6 Bus display after OPS 2 transition

First, I am doing the GNC OPS 2 transition ( no Launch Data Bus assigned on GPC 1 and 2)

Image


After transition, the LDB 2 is still assigned to GPC 2 ( in spec 6)

Then I did the SM transition, everything went well ( Pay load Bus assigned to GPC 4)

Image

On spec6, PL bus were well assigned to gpc 4


Then I did an Ops recall for GNC GPC, and I didn't see anymore the PL assigned to GPC 4

Image

That is an old thing I saw since the first iteration of advanced GPC

To sum up, LDB assigned to GPC 2 (instead of 4) and PL bus not assigned to GPC 4 on Spec 6 when it should be the other way around with a correct OPS 2 transtition for GNC and SM
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Re: Space Shuttle - Bugfixes

Postby wlbragg » Tue Dec 31, 2019 5:16 am

I suppose the following bug could be causing both the particle to fail and maybe even the Speed Brakes to be open?

Image

Right after Trim Statistics in the log.
Code: Select all
  178.35 [ALRT]:nasal      Nasal runtime error: nil used in numeric context
  178.35 [ALRT]:nasal        at /mnt/GDrive/Aircraft/Development Aircraft/SpaceShuttle/Nasal/limits.nas, line 646
  178.35 [ALRT]:nasal        called from: /mnt/GDrive/Aircraft/Development Aircraft/SpaceShuttle/Nasal/stages.nas, line 3097
  178.35 [ALRT]:nasal        called from: /home/wayne/FGFS/install/flightgear/fgdata/Nasal/globals.nas, line 119


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Re: Space Shuttle - Bugfixes

Postby Thorsten » Tue Dec 31, 2019 8:11 am

646 of limits.nas in my version is

Code: Select all
var qbar_limit = getprop("/fdm/jsbsim/systems/various/qbar-limit-entry");



that line can't produce the error because fetching the NIL is usually silent.

Needless to say, that line couldn't actually be reached during ascent, because it refers to entry and approach phase limit checks. Which, oddly enough, would explain why the speedbrake is open, because approach logic would do automated speedbrake checks.

The whole situation is so messed up, I can't even begin to speculate what happened - I suppose you never saw this in 2018.3? I recommend a regression test, and if it goes away in 2018.3, a report on the mailing list.
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Re: Space Shuttle - Bugfixes

Postby wlbragg » Tue Dec 31, 2019 4:14 pm

I'll have to run a "stable" build, which I can do easy enough to check regression. All except fgdata which I may be able to fudge.
I'll see if I can step through a couple interim releases builds, starting at 2018.3 and see where this started for me.

646 on mine is...
Code: Select all
if ((pitch_rate < -2.0) and (getprop("/gear/gear[0]/wow") == 1))

which somewhat explains at least why it appears to be speed brake and gear particle effect of some kind. How we get there on ascent???
pitch_rate is...
Code: Select all
var pitch_rate = getprop("orientation/pitch-rate-degps");


I'm still having issues with AirCrane, and I think it is a position or orientation property that isn't getting loaded at a proper timing anymore, where it used to. Looks similarly suspicious to to me.
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Re: Space Shuttle - Bugfixes

Postby wlbragg » Tue Dec 31, 2019 5:53 pm

I'm getting all the landing cues on ascent, tail drag, gear deployment at high speed, etc.

Also, anyone know why this structure is at LC 39A? I think it may be in the models database/

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Re: Space Shuttle - Bugfixes

Postby legoboyvdlp » Tue Dec 31, 2019 9:43 pm

That's the ramp - the shuttle is meant to sit on top, but doesn't seem to.
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Re: Space Shuttle - Bugfixes

Postby wlbragg » Tue Dec 31, 2019 10:13 pm

legoboyvdlp wrote in Tue Dec 31, 2019 9:43 pm:That's the ramp - the shuttle is meant to sit on top, but doesn't seem to.

Structure and all or is the ramp supposed to replace the structure?

First preliminary tests indicates the issue may be in FGDATA and not the fgfs build itself, would that make any sense?
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Re: Space Shuttle - Bugfixes

Postby legoboyvdlp » Tue Dec 31, 2019 10:42 pm

Actually - sorry, I didn't notice - yours spawns on top of the ramp. Mine always launches on top of the launch gantry but embedded inside the ramp - I think it takes a while to load up the model so by the time its loaded, the shuttle is already initialised on the ground? The ramp is the base that the gantry itself sits on.
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Re: Space Shuttle - Bugfixes

Postby Thorsten » Wed Jan 01, 2020 8:36 am

Structure and all or is the ramp supposed to replace the structure?


The Shuttle sits on a mobile platform - and is transported from the VAB with crawler. For launch, the crawler is driven up the ramp, then then the platform is secured. At this point, the gantry is still closed and used for servicing the whole assembly, Then the gantry is opened pre-launch and off she goes.

The virtue of the ramp is having the flame trench (the whole engine exhaust going into a flat surface might actually start to blast back) and the sound suppressing system (lots of water dumped into a basin).

So in theory what we'd want is orbiter sitting on mobile platform sitting on ramp sitting on terrain. Phrased like this, you're probably starting to spot the problem - it needs to be choreographed. Even close-by terminal buildings may appear quite a while after the aircraft has been loaded, so spawning 'on top' of a structure is not particularly innocent.

Maybe someone figures out how to get on top of the ramp one of those days - it's not a big priority for me at the moment.
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Re: Space Shuttle - Bugfixes

Postby wkitty42 » Wed Jan 01, 2020 5:15 pm

i also note that the gantry and shuttle are not properly oriented to the ramp...

in the picture, we see the crawler carrying the shuttle up the ramp... the vertical stabilizer always points toward the south as there's no way to turn the shuttle once it is on the crawler... and the ramps are north/south oriented so the crawler climbs up the ram heading north...
Image

closer to the gantry...
Image

two shuttles sitting on their crawlers at their gantries ready for launch...
Image

i spent some time yesterday attempting to launch into at least the ISS orbital plane... i wan't sure about the necessary --heading to use and finally settled on --heading=0 via the launcher's location tab with some lon and lat coords i found... i think the coords i used were in the free shuttle manual but they're off a little bit and not on one of the ramps... i also used my google earth to find the ramps and draw a path line from the end of the ramp to the roadway so i could determine its actual heading... zero it was so i used that heading when loading the sim... my next step will be to find more accurate coords... i have some around here with some details of the pads... i have to try to find them... in any case, it is something to play with ;)

[edit] i found the pictures i have from some documents but they do not have a compass rose on them to point to north so they're ok for some stuff but... i can make the pictures available but i do not recall which docs i got them from... they were definitely from NASA though...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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