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Space Shuttle - Development

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Re: Space Shuttle - Development

Postby Thorsten » Fri Oct 04, 2019 1:56 pm

Actually I was wondering - how can you see flames in a near-vacuum?


Why would you not? Flames are visible because the chemical reactions excite electrons in molecule orbitals which emit light when they de-excite. You need air to keep a combustion reaction in a fire going, and generally you need an oxidizer to do that in space, but a rocket engine comes with both fuel and oxidizer merged in the combustion chamber.
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Re: Space Shuttle - Development

Postby legoboyvdlp » Fri Oct 04, 2019 2:16 pm

I imagined the vacuum would cause gases to expand rapidly to fill the vacuum such that they wouldn't be visible.

Thanks for the explanation.
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Re: Space Shuttle - Development

Postby wkitty42 » Fri Oct 04, 2019 4:58 pm

legoboyvdlp wrote in Fri Oct 04, 2019 2:16 pm:I imagined the vacuum would cause gases to expand rapidly to fill the vacuum such that they wouldn't be visible.


ummm... ;)

"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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Re: Space Shuttle - Development

Postby Thorsten » Fri Oct 04, 2019 5:08 pm

I imagined the vacuum would cause gases to expand rapidly to fill the vacuum such that they wouldn't be visible.


Well, that's why exhaust flames are narrow collimated streams in air but wide expanded in vacuum. At liftoff, the Shuttle exhaust actually looks pretty much like a fighter jet engine with AB on, but in vacuum it's like a parabola, much wider.

So in a sense they're better visible in air because the flame is more collimated, but during the day there's also more background brightness...
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Re: Space Shuttle - Development

Postby GinGin » Sat Oct 05, 2019 5:35 am

I give a thorough test on failure scenarios.
Really nice with the upgraded caution and warning systems.

One minor thing I noticed : for an engine failure, we should have a red master warning alarm ( like for a MPS failure )
Apart of that, being able to forecast failure vie the mission files and the custom card in the cockpit are such a great addition to realism and immersion .
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Re: Space Shuttle - Development

Postby Thorsten » Sat Oct 05, 2019 6:41 am

One minor thing I noticed : for an engine failure, we should have a red master warning alarm ( like for a MPS failure )


That certainly seems doable... I'll look into it.
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Re: Space Shuttle - Development

Postby Thorsten » Sun Oct 06, 2019 8:41 am

I've just applied a fix to spurious altitude variations for the orbital target - this was an unintended side-effect of trying to improve the orbital plane, so it should now be a bit better-behaved in the rendezvous endgame.

Note: It's an FGData side fix, not Shuttle-side, affecting FGData/Nasal/orbital_target.nas
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Re: Space Shuttle - Development

Postby eatdirt » Sun Oct 06, 2019 7:54 pm

Very nice!
I gave a try to latest fgspaceshuttle snaphot, together with a snaphost of flightgear branch next, and I see a few things in the console:

Code: Select all
   35.59 [ALRT]:nasal      Request detected to initialize Advanced Weather on startup...
   35.62 [ALRT]:nasal      Volcanic activity off.
   35.89 [ALRT]:nasal      Loading local weather routines...
   35.90 [ALRT]:nasal      Animated jetways ... initialized
   36.03 [ALRT]:nasal      Nasal runtime error: nil used in numeric context
   36.03 [ALRT]:nasal        at /home/chris/.fgfs/Aircraft/SpaceShuttle/Nasal/rel_orbital.nas, line 2902
   36.03 [ALRT]:nasal        called from: /home/chris/.fgfs/Aircraft/SpaceShuttle/Nasal/rel_orbital.nas, line 2226
   36.03 [ALRT]:nasal        called from: /home/chris/.fgfs/Aircraft/SpaceShuttle/Nasal/rel_orbital.nas, line 3189


  113.77 [ALRT]:nasal      Nasal runtime error: nil used in numeric context
  113.77 [ALRT]:nasal        at /home/chris/.fgfs/Aircraft/SpaceShuttle/Nasal/HUD/HUD_main.nas, line 951
  113.77 [ALRT]:nasal        called from: /home/chris/.fgfs/Aircraft/SpaceShuttle/Nasal/HUD/HUD_main.nas, line 1008
  113.77 [ALRT]:nasal        called from: /home/chris/.fgfs/Aircraft/SpaceShuttle/Nasal/HUD/HUD_main.nas, line 1021
  113.77 [ALRT]:nasal        called from: /home/chris/.fgfs/Aircraft/SpaceShuttle/Nasal/HUD/HUD_main.nas, line 1025
  113.80 [ALRT]:nasal      warthog: read file $FG_ROOT/Input/Joysticks/ThrustMaster/Warthog/README
  113.80 [ALRT]:nasal               for how to enable FlightGear to set backlight and LEDs etc.



and indeed, the HUD remains frozen during launch at all times! Let me know if you need other information!?
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Re: Space Shuttle - Development

Postby legoboyvdlp » Sun Oct 06, 2019 10:28 pm

At least I now know it's not just me... It's really odd. Those properties are set in jsbsim - so they are for some reason nil when they shouldn't be.
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Re: Space Shuttle - Development

Postby Thorsten » Mon Oct 07, 2019 4:45 am

Again, this smells like a core-side change of... something, but we need to identify what caused it.
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Re: Space Shuttle - Development

Postby Thorsten » Mon Oct 07, 2019 6:11 am

I've written a note to the mailing list.
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Re: Space Shuttle - Development

Postby GinGin » Thu Oct 10, 2019 1:25 pm

Thorsten wrote in Sun Oct 06, 2019 8:41 am:I've just applied a fix to spurious altitude variations for the orbital target - this was an unintended side-effect of trying to improve the orbital plane, so it should now be a bit better-behaved in the rendezvous endgame.

Note: It's an FGData side fix, not Shuttle-side, affecting FGData/Nasal/orbital_target.nas


Very Nice thanks.
I Il try that with old save near Hubble .
What was the side effect ?

Small thing I noticed during Nz pullout for RTLS and contigency , AP is always maintenant a slightly smaller nz than the one forecaste ( 2.3 for 2.8 g in my last RTLS)
I take css then to pinpoint the nz , helping a lot for low energy situations that arise with a smaller Nz maintened through the pullout .
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Re: Space Shuttle - Development

Postby Thorsten » Wed Oct 16, 2019 10:24 am

I've started now re-working 'The Manual' - no big new chapters this time, but lots of small bits here and there...

is always maintenant a slightly smaller nz than the one forecaste ( 2.3 for 2.8 g in my last RTLS)
I take css then to pinpoint the nz , helping a lot for low energy situations that arise with a smaller Nz maintened through the pullout .


I'm not sure - I guess it lags a bit? Admittedly I was happy to teach the AP at all to fly Nz pullouts back then... Let's put it on a list of things to look at after the next milestone...
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Re: Space Shuttle - Development

Postby GinGin » Wed Oct 16, 2019 3:07 pm

Yes sure :)
I am finishing a video on RTLS and made dozens of them, and it always stays a tad below the target.
Minor thing, as it still works like a charm, but energy is even better managed when right on the good Nz

Thanks for the manual
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Re: Space Shuttle - Development

Postby Thorsten » Sat Oct 19, 2019 4:22 pm

GPC being voted out of the redundant set:

Image

I've pushed a few changes to init sequences today - basically we defer initialization of the HUD a bit and also do the error set for the orbital target only when we're actually in orbit - I have no idea of whether this actually fixes the Nasal errors which have appeared - but it just might.
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