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Space Shuttle - Development

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Re: Space Shuttle - Development

Postby wkitty42 » Tue Oct 01, 2019 5:10 pm

yeah... i tend to shy away from "if...else if...else if...else if" stacks... i hadn't thought about a boolean status flag...
"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 » Tue Oct 01, 2019 6:15 pm

You could over-design this and use an array to look up the current conditional values and increment the array index whenever the condition is true. I'm not sure whether this gets significantly faster in practice that way - the main goal is just to avoid plenty of property I/O every iteration.
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Re: Space Shuttle - Development

Postby GinGin » Wed Oct 02, 2019 7:39 am

Ok, good
I will have a look to aux flag and come back with a cleaner thing then :)

Is there an easy way to stop the ssme sound in the cockpit after srb sep ?
After several readings and comments from astronauts , ssme weren’t heard .

Currently, I just lower the sound via general settings, but is lowering also caution warning sounds .
I found the ssme sound command in various internal properties , but don’t real know how to interact with it .

Thanks :)
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Re: Space Shuttle - Development

Postby Thorsten » Wed Oct 02, 2019 7:45 am

After several readings and comments from astronauts , ssme weren’t heard .


Seriously? How is that even possible if the OMS engines are audible? I won't make any such change without very good research...

I can sort of buy into the argument that the pumpkin suits would dampen sound drastically - but then we need a simulation of those anyway (when there's a leak in the cockpit and the air goes out...) - but that would also affect the high frequencies of the SRBs and make all C/W sounds inaudible as well. That's generally a fairly complex problem (which I've really come to appreciate while making movies...)

Anyway, for your own enjoyment you could simply comment out the SSME sound section in the sound definitions - then it'll never be heard.

Aka, find that in Sounds/SpaceShuttle-Sounds.xml and comment it out:

Code: Select all
   <main>
      <name>main</name>
      <mode>looped</mode>
      <path>Sounds/exhaust_loop.wav</path>
      <condition>
         <property>/sim/current-view/internal</property>
      </condition>
      <volume>
         <property>/fdm/jsbsim/systems/various/SSME-base-volume</property>
         <factor>0.01</factor>
         <offset>0.0</offset>
         <min>0.0</min>
         <max>1.0</max>
      </volume>   
      <pitch>
         <min>0.005</min>
         <max>0.005</max>
      </pitch>
   </main>
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Re: Space Shuttle - Development

Postby GinGin » Wed Oct 02, 2019 8:02 am

Perfect thanks.
I will post more infos on that when on the desktop computer.

But to start with, scom page 918/919

Ssme Sounds is decreased a lot and almost unheard after srb sep.An astronaut joke was about wondering if engines were failed or not and looking at visual/ audio warning cues
Aft rcs don’t produce sounds but just vibrations .
And Oms dont produce sounds ( page 919)
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Re: Space Shuttle - Development

Postby Thorsten » Wed Oct 02, 2019 8:35 am

At SRB SEP, g-load undergoes a nearly instantaneous reduction from 2.3 g to 1.0 g, coupled with a significant reduction in noise and vibration.

Not really the same thing as silence (SCOM 7.1-10).

And Oms dont produce sounds ( page 919)

I distinctly remember reading that they do, although I'm not sure where I found this bit.
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Re: Space Shuttle - Development

Postby Thorsten » Wed Oct 02, 2019 9:23 am

After getting my headphones out and listening to some launch footage from 3 miles away, I grant you that the boosters are a lot (estimated 10) times louder than the main engines (with the appropriate delay, you hear first the main engine ignition and then the sound really gets up when the boosters ignite).

So that could be more pronounced.

I've tried in vain to find a video where an OMS firing aboard is shown with the real sound level - though there is amusing footage where astronauts are kicked through the mid-deck by the burn.
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Re: Space Shuttle - Development

Postby GinGin » Wed Oct 02, 2019 2:51 pm

though there is amusing footage where astronauts are kicked through the mid-deck by the burn.


Do you have the link? It seems funny :)


So indeed for the significant reduction of noise after SRB sep, plus the pumpkin, air con noise, etc, explain the really thin roaring almost silent heard in the cockpit then.
In Ascent Handbook, they speak about the stop of a small background noise as a cue for MECO.

For OMS, Both in SCOM and Handbook , it is mentionned that it is noiseless.
Quite coherent after all. If a million pound engines are barely heard, 12000 pounds engines have no chance to be noisy
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Re: Space Shuttle - Development

Postby eatdirt » Wed Oct 02, 2019 4:39 pm

LOL... If you remember an old post of mine, I have actually a bug that makes the SSME sound disappearing around the time of SRB sep.... Now you tell me guys that my computer decided alone to improve the realism of the simulation!! :D

By the way, since I have been flying with no sound after SRB sep, you'll see that it is quite disturbing actually!
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Re: Space Shuttle - Development

Postby GinGin » Wed Oct 02, 2019 4:52 pm

Excellent Chris.
It is precognition :)

I am testing Failures I never touched before ( Helium Leak, OMS leakage,etc )
Excellent with the cue cards in the cockpit now
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Re: Space Shuttle - Development

Postby GinGin » Thu Oct 03, 2019 1:59 pm

I just found that video.
Really nice comms, not too much chatting like we can see on some Comms video.
And nice for sound ambiance

https://www.youtube.com/watch?v=PsHljHRM67c
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Re: Space Shuttle - Development

Postby Thorsten » Thu Oct 03, 2019 2:32 pm

I've now removed the 'equipment' weight.

Also, I've pondering the CoG issue just prior to MECO when the gimbals tend to be saturated as the CoG moves backward (which is an issue for MECO in aborts with the center engine gone). Basically I see no real way to resolve it except to give the engines a little extra angular slack. The justification for this would be the observation that the thrust structure apparently bends under load and some extra angle can be recovered by load relief - as the engines are throttled back towards MECO, essentially just that wiould happen. Since I do not have a credible bending model, extra angle is the next thing I can think of, so at this point I don't think it's just an ad-hoc cheat, the real situation apparently was marginal as well.
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Re: Space Shuttle - Development

Postby eatdirt » Thu Oct 03, 2019 10:23 pm

Really nice comms, not too much chatting like we can see on some Comms video.


Very nice!!!!!! It seems that someone is hoovering the cockpit before ignition!? :)

And serious wind noise around qbarmax!!!! That's actually quite scary. From the fact the we also hear one of them turning pages later one, the sensitivity of the microphone seems to be good enough to say that we really don't hear the SSME running. Although this should be renormalized with the microphone bandwidth I guess, which sounds quite narrow.
It also sounds like ET sep is quite close to someone closing a car's door?!
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Re: Space Shuttle - Development

Postby GinGin » Fri Oct 04, 2019 9:44 am

The hovering noise is air con and apu sounds.
Srb and et sounds are very loud , like the forward rcs which sound like a canon :)

Glad you like the video

Nice Thorsten for the center engine , nice proof of the good fdm if we observe sim stuff like that without forecasting them :)
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Re: Space Shuttle - Development

Postby legoboyvdlp » Fri Oct 04, 2019 1:29 pm

If you see a video of the OMS firing you see a huge expansion of white vapour / fumes out the back before it settles down to provide thrust - so that's probably why there is a sound almost like an explosion! Really interesting to watch these videos :)

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