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Space Shuttle - Bugfixes

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Re: Space Shuttle - Bugfixes

Postby eatdirt » Tue Feb 09, 2021 5:26 pm

A few minor additions to Thorsten's tests:

1) On BFS only, I am getting a CWS error message about MPS LO2/H2 manifold pressure a few seconds after lift-off

2) The display PC < 50 before SRB separation shows up on all screen but not on BFS (I thought it was only on BFS?)

3) On orbit, the Freon Loop CWS is triggered on a regular basis, I suspect it is just getting too cold by night (as I spotted in another post). Maybe should we relax a bit the limits?

I am running full realistic.

Cheers.
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Re: Space Shuttle - Bugfixes

Postby GinGin » Tue Feb 09, 2021 5:38 pm

the display PC < 50 before SRB separation shows up on all screen but not on BFS (I thought it was only on BFS?)


Yes, it is on Both at a different place on the last Operationnal Increment (33)

On BFS only, I am getting a CWS error message about MPS LO2/H2 manifold pressure a few seconds after lift-off


Indeed, initial pitch down acceleration sometimes trigger the high pressure in the MPS feedlines.
I will set a higher trigger for initial stage
BFS only message is normal, no PASS message for that failure ( all the fault messages implemented are on the link I gave early on https://onedrive.live.com/?authkey=%21ANumIX3Vf7wWrZA&cid=B8BA5CCBC22FB3F0&id=B8BA5CCBC22FB3F0%21117&parId=B8BA5CCBC22FB3F0%21115&o=OneUp )

the Freon Loop CWS is triggered on a regular basis


We can, it just warn you that you can do something about the low temp ( playing with the radiator flow, or shutting down the Hi Load flash evap.
It is set at 20 °F so far ( lower than in reality to take into account the FG shuttle thermal distribution)

We can lower it, I just find interesting to have a trigger like that.
It is not that noisy in my opinion, and we can act on it
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Re: Space Shuttle - Bugfixes

Postby eatdirt » Tue Feb 09, 2021 6:40 pm

It is not that noisy in my opinion, and we can act on it


Yes, I agree, I was just mentioning it in case it was unintended, that's really not a problem.
But, indeed, it gets cold, I am on radiators only, no flash evap, since 2 days in orbit, and even during day, temps can get down to 6 degrees!
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Re: Space Shuttle - Bugfixes

Postby Thorsten » Wed Feb 10, 2021 6:57 am

Did you have the thermal acceleration enabled or did you wait a very long time on ground before lifting off?


Neither. I explicitly checked my simulation settings, so I know for a fact thermal simulation was not accelerated. I estimate I didn't spend more than 5 minutes on the pad, basically I switched the APUs on, checked out a few displays and then went off into space.

***

But, indeed, it gets cold, I am on radiators only, no flash evap, since 2 days in orbit, and even during day, temps can get down to 6 degrees!


It is set at 20 °F so far ( lower than in reality to take into account the FG shuttle thermal distribution)


We don't really have to change trigger values - if there's good data that the initial temperature is too hot, we can make it colder while on the pad, if in the long run it gets really cold, we can decrease albedo a tad and make it pick up more sunlight. There's no table of Shuttle thermal data I've been using at any point, the thermal simulation is a fair part of guesswork that can be credibly adjusted to match reality better.

(Performance numbers and so excess heat of computers or the APUs are based on data of course - but already the thermal coupling of this equipment to the water and freon loops is guesswork).

So... let's gather the data :D
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Re: Space Shuttle - Bugfixes

Postby Thorsten » Wed Feb 10, 2021 6:03 pm

Another launch and another entry later (I actually rolled into the grass for admiring the new drag chute colors :mrgreen: )...

I can't say for sure, but I had the impression that RTHU is a tad less stable with the new launch AP than it used to be - there's some poorly damped roll oscillation in the end which I don't really remember having seen before. Do we need more damping?

Also, I was delivered with RINC of 0.2 deg into orbit - used to be 10 times as precise - did we loose here?

Since people have been reaching ISS, I assume RINC can be 'good enough' still - is that a fact, or more generally observed?

Entry on the other hand worked like a charm (all lines of all five displays are still superimposed though, I guess that's still on the to-do list?)
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Re: Space Shuttle - Bugfixes

Postby GinGin » Wed Feb 10, 2021 6:54 pm

since 2 days in orbit, and even during day


Wow, nice.
I have never been so long in a sim session.
Is it working good?


I explicitly checked my simulation settings, so I know for a fact thermal simulation was not accelerated.


Alright. I have never experienced a Freon Alarm that early so far.
If it happens again , could you indicate me the Freon temp in the systems/thermal-distribution ?


So... let's gather the data


I have a lot of thermal datas about that in the Post flight/lessons learned Books from where I took datas for Entry/TAEM corridors and boundaries.
I will put them on my dropbox.



I had the impression that RTHU is a tad less stable with the new launch AP than it used to be


It has always been a bit unstable especially in yaw ( except for TAL where there is no Inc targeting)
I remember that I changed it a bit to have it more yaw stable (no delta inc correction during RTHU) and yaw wise it is better.
We can make it even more stable indeed for the roll at the end.


Also, I was delivered with RINC of 0.2 deg into orbit - used to be 10 times as precise - did we loose here?


It is more accurate without the RTHU
I tried one with the ISS mission file ( automatic ignition 2 mn after sim session loaded). I provided good launch window for ISS and Hubble ( 2mn automatic countdown and 10 mn values on top of each mission file in green)
I am between 0.05° without RTHU and 0.15° with RTHU

0.15° gives me around 50ft/s of Planar change burn.


Entry on the other hand worked like a charm (all lines of all five displays are still superimposed though, I guess that's still on the to-do list?)


I completely finished the Entry and TAEM rework.
I was waiting the merge of the FDM before pushing the rest, as it is quite dependant of the changes in Basic Cd/Cl at higher mach.
The superimposed thing is "normal" without the proper pfd_entry.nas




rolled into the grass for admiring the new drag chute colors


And I rolled on the belly :mrgreen:

Image
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Re: Space Shuttle - Bugfixes

Postby eatdirt » Wed Feb 10, 2021 8:14 pm

I have never been so long in a sim session.
Is it working good?


Oh yea, that works very well, 2020.3.6 is super stable as far as I can tell. Even the loading of Earthview sectors is surprisingly fast. I am at ease, docked onto ISS, and every morning, just after taking a real leak, I am purging the virtual fuel cells before heading to real work. Easy to remember ;)

Tonight is time to land, I have at last a trajectory nailing KTTS at the right social time to do the job (me at home and kids sleeping). I am quite rusty after 2 months without Shuttle training, let's hope for the best!
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Re: Space Shuttle - Bugfixes

Postby eatdirt » Wed Feb 10, 2021 11:44 pm

I didnt push OPS 3 rework for now.


You actually fragged me on that one, as if I was not stressed enough for reentry :D --->

Like, I am ready, here we go:
OPS 304
then
Image

"HOLY S...." :D

PS: I am gonna post some pictures on the Spaceflight, in addition to a broken APU, fuel leaks a bit everywhere, I did some serious stunts for landing, 4 days in space, no state vector update, I got it hard in my face when the MLS switched on at the same time a bloody giant cumulus was obstructing the view :)
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Re: Space Shuttle - Bugfixes

Postby Johan G » Thu Feb 11, 2021 9:13 am

Saw screenshot: Oh, wow. :shock: :lol:
Read PS: "One accident is rarely alone"... :lol:

So, how was the landing? :wink:
Low-level flying — It's all fun and games till someone looses an engine. (Paraphrased from a YouTube video)
Improving the Dassault Mirage F1 (Wiki, Forum, GitLab. Work in slow progress)
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Re: Space Shuttle - Bugfixes

Postby eatdirt » Thu Feb 11, 2021 11:06 am

So, how was the landing?


Like this ;)

viewtopic.php?f=87&t=35078&p=381376#p381339

Full videos coming, need to make something clean from 4 days of recording!
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Re: Space Shuttle - Bugfixes

Postby Thorsten » Thu Feb 11, 2021 2:53 pm

So, I've made some progress with the Freon Loop - it seems that the initial temperature is very close to 291 K and rises for some 3 minutes before it drops down again. Which is why GinGin, spending 15 minutes on the PAD, doesn't see this.

More vexingly is the fact that for OPS 1 the relevant temperature should be 319 K, so this should not happen.

I suspect

Code: Select all
   systems/dps/ops != 1


should rather be

Code: Select all
   systems/dps/ops  NE 1


(JSBSim is fond of more Fortran-ish syntax at times at NE is what the manual states) and that the statements might simply not register, so I've tentatively made the changes.

Starting in TAEM, I immediately get an engine reposition failure error - we should not init scenarios such that failure messages are unavoidable, so I'll investigate that next if no one beats me to it.
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Re: Space Shuttle - Bugfixes

Postby GinGin » Thu Feb 11, 2021 3:09 pm

Starting in TAEM, I immediately get an engine reposition failure error - we should not init scenarios such that failure messages are unavoidable, so I'll investigate that next if no one beats me to it.


I fixed it already (it will be in the next stages.nas push)
I added the SSME TVC opened in the Hydraulic_on(); TAEM initialisation preset.



Copied for the NE
Actually, I never had the freon alarm even when I liftoff one mn after init.
So maybe the "!=" was ok on Windows (?) and not Linux

Lets see if the NE fixes that :)
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Re: Space Shuttle - Bugfixes

Postby Thorsten » Fri Feb 12, 2021 1:42 pm

I finally solved the Freon loop warning - it's a versioning problem. The <switch> is using nested conditionals, which however haven't been supported by JSBSim for a looong time, they were only enabled in 2020 (?) - so with me using an older FG version that makes them produce rubbish. I'll simply convert all nested conditionals to the classic syntax, there's no real advantage from using the new nested version except a few lines of space shorter code - and it'll just work for everyone.
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Re: Space Shuttle - Bugfixes

Postby GinGin » Fri Feb 12, 2021 4:35 pm

Ah ok, good finding.
I will check also where I used them elsewhere.
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Re: Space Shuttle - Bugfixes

Postby Thorsten » Mon Feb 15, 2021 12:39 pm

Seems there's still work ahead... I've just tried a TAL to Banjul, and the MECO condition was dead wrong - despite activating low energy logic, I ended up some 400 miles before the runway in the ocean.

Not a happy crew...
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