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Space Shuttle

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Re: Space Shuttle

Postby Thorsten » Sat Jul 22, 2017 6:52 am

dds is pre-compressed and mipmapped and hence loads much faster, but it is a proprietary format and hence frowned upon in the free software world (it may not run at all under Linux OpenSource graphics drivers). Under Windows, you usually want dds (but you'll have to edit the file to reference the correct textures).
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Re: Space Shuttle

Postby erik » Sat Jul 22, 2017 7:15 am

It looks like the new KTX format is designed to replace DDS for OpenGL and Vulkan:
https://www.khronos.org/opengles/sdk/tools/KTX/

I read supporting it is mandatory for new drivers so by this time it should be supported pretty well.

Update, it is even used by large commercial projects so I think it's time to just forget about DDS:
https://www.warsow.net/forum/thread/16807/1
I noticed that Warsow uses a lot of textures in the .ktx format.


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Re: Space Shuttle

Postby GinGin » Sun Jul 23, 2017 8:39 am

Good Morning,

I managed to install HD textures into FG/Scenery/Terrain and the High resolution Cloudd and World.jpg into Earthview ( did not really understand for the dds one)
Quite very beautifull once in Orbit.

I had some weird things. When I start from the FG menu that I got on my desktop, where I can choose Location, Aircraft, Add on, and enter command line, I am always starting in the Sea, even with Tiles installed.

However, if I am starting the game directly from the FGFS.exe located in FG root, the game starts with cessna already in Boston, terrain is here and when I change to Space shuttle at KSC location, it works and load the scenery, weird no?


Also, when I called Spec 1, I can't change the NBAT assignement on the left, I thought we could from the manual? Is it a problem in my game or normal?


Thorsten, I had a look to recirc Pump in action monitoring the Elec Disp, a true hog yes :) every pumps take almost 100 Amps and decrease voltage by one volt of the concerned FC, nice entertainement .
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Re: Space Shuttle

Postby Thorsten » Sun Jul 23, 2017 8:51 am

You probably have the wrong scenery folder selected in the launcher - since the location is configurable, you get the default one with the 'bare' program but the launcher-selected one with the launcher.

did not really understand for the dds one


Open

$FGData/Models/Astro/earth_uniscale_hires.ac

in a text editor (notepad++ does well under Windows). Make a copy of the file.

There's eight lines like

Code: Select all
texture "Textures/world_N1.png"


in there.

Simply replace png by dds, make sure the dds textures are installed under

$FGData/Models/Astro/Textures

(where the png textures are), and if all went well, you'll enjoy the dds set.

Also, when I called Spec 1, I can't change the NBAT assignement on the left, I thought we could from the manual?


You can't do all stuff as far as I remember, you can edit the software config for the next OPS for sure. It's been a while since I coded it.
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Re: Space Shuttle

Postby GinGin » Sun Jul 23, 2017 9:07 am

Perfect,
Thanks for the explanations.

Still busy with BFS ? :)
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Re: Space Shuttle

Postby GinGin » Sun Jul 23, 2017 9:15 pm

I tried some RTLS, really nice, and I have correct path for scenery now ahah, thanks.

So many clickable switch :)

Image

It looks better :

Image

Image



View of the tower:

Image



Breaking the clouds layer

Image



A question concerning those fumes, is it coming from the LH2 Back Up valve? If yes, is it normal to have it before normal MECO? I don't remember if for RTLS it's start as soon as you engage RTLS abort mode.

Image



So nice to have OPS 6 and Spec 51 to play with,

Image




OMS to RCS interconnect and dump, check

Image



Dump completed, Fault message for OMS low pressure and quantity

Image



I love those lights effect

Image



Just passing the Vrel=0 dangerous zone, on track

Image



PPD

Image



MECO

Image



Nice view from the GRTLS

Image



Unfortunately, I was a bit short by at least 50 Nm for this one, I follow the guidance, but no joy

Image


And a beautiful Borealis Aurora to finish, great

Image
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Re: Space Shuttle

Postby Thorsten » Mon Jul 24, 2017 6:44 am

A question concerning those fumes, is it coming from the LH2 Back Up valve? If yes, is it normal to have it before normal MECO?


That's the FES exhaust plume. Which admittedly shouldn't be there very low in the atmosphere...

Unfortunately, I was a bit short by at least 50 Nm for this one, I follow the guidance, but no joy


This is somewhat embarassing...

I've just tried to redo this based on what I could see on your screenshots to see what happened.

* 1ST EO VI 5747 happens for me 2:47 into the flight (low inclination launch from KSC, empty Shuttle). That's well into the region where a TAL is available without payload (and outside the region where I've tested the RTLS, I think most of my tests were 1st stage engine failures)

* letting the AP fly the trajectory brings me to pitchdown at 7100 fps site-relative speed with 339 miles to site - the ideal MECO distance computed by guidance would be 288 miles

* now, there is a correction done to aim for the ideal distance modifying MECO target speed - which would suggest to go ~1000 fps higher

* however, out of qbar limit violation concerns, I have clamped that calculation to [-300, +300] around nominal MECO target velocity, so the correction is not fully applied

* and as a result you get short

* and since the cutoff is guidance-controlled whenever you're using RTLS guidance, you can't even fix this manually :?

-> However, my concern seemed to be baseless, since qbar at ETsep was at the lower end of the target range, thus I've increased the clamping window from 300 to 800 which should handle a late return trajectory more gracefully

-> Sadly I couldn't test this because some of my recent fiddlings (probably with NO Y JET) seem to have screwed something with the handover from powered to unpowered flight in the devel version (probably an uncaught integrator windup) so I need to track and fix this first.
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Re: Space Shuttle

Postby Catalanoic » Mon Jul 24, 2017 1:28 pm

Just a question. these launch structures and the pad itself are objects added with the Shuttle or are part of custom scenery? thanks in advance
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Re: Space Shuttle

Postby Thorsten » Mon Jul 24, 2017 1:39 pm

Just a question. these launch structures and the pad itself are objects added with the Shuttle or are part of custom scenery


They come with the Shuttle, as part of allowing the user to launch everywhere he wants.

Sadly I couldn't test this because some of my recent fiddlings


Okay, I've tried a failure of the left engine at 2:45 into the flight and the AP flew that one bang-on into the nominal TAEM pattern. So one wouldn't guess that it misses a fairly similar problem by some margin...
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Re: Space Shuttle

Postby GinGin » Mon Jul 24, 2017 4:37 pm

Thanks for you Quick return

Nice for the FES, it makes sense I was way above 120000 feet, so very nice fine tunning.

Yeah I was letting AP all the way to see how he was handled it, i saw it was a bit late for Ppa. CSS works well ?

I love to test all those stuff
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Re: Space Shuttle

Postby Thorsten » Mon Jul 24, 2017 5:03 pm

CSS works well ?


Well, MECO occurs commanded by guidance even if you fly by hand - and in the event it's hard to do it otherwise, because nearly immediately after MECO rates and beta need to be nulled (done by the RCS) and then Aerojet needs to be engaged and the MPS dump started - and you have no viable time window to do that manually, there's probably 10 seconds to get it all done. If you even delay the MPS dump too much, you'll be off-trim in the atmosphere and unable to do Nz holding.

(Of course one could code a manual MECO detection..., but if you cut the second engine guidance is going to think we need a contingency abort, so there's that...)

So you can't really influence the MECO ranging even under CSS (except by modifying the trajectory, pitcharound point etc...).

The problem is really that the parameter space in terms of launch inclination, payload and engine failure time is quite huge - I have tested a subset of it, but there's no guarantee that every case is covered :? And it's by and large a honest simulation - the aerodynamics, thruster performance and limits are as they are, and if you violate any, you suffer the consequences.
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Re: Space Shuttle

Postby GinGin » Tue Jul 25, 2017 12:48 am

Mmm ok, I was thinking to take it in CSS to do an early PPA (influence as you said PPA point and trajectory) and then once approaching PPD put it back to auto to let it handle the time critical phase to prepare it for MECO.
Will it work if I do manually the PPA earlier and let it handle in auto after?

Then I let it do Alpha recovery, Nz hold and Alpha transition and take it back to CSS for GRTLS and TAEM.
I am really curious to see if I can handle Nz hold manually, without breaking a wing.

"And it's by and large a honest simulation"

That's what we like, even if it's sometimes unforgiveable :)
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Re: Space Shuttle

Postby Thorsten » Tue Jul 25, 2017 7:02 am

Will it work if I do manually the PPA earlier and let it handle in auto after?


Not generally. Guidance internally has its phases - if you pitch around before guidance transits to the flyback phase, the AP will pitch you back when engaged, concluding correctly that you're off-attitude for a fly-out.

On the other hand, if you are in the same phase, it'll probably work (unless there's the possibility of an uncaught integrator windup). You have limited insight into what phase guidance is in, for instance via the percentage counter.

But once you take over, you can actually fly manually to MECO - it's not that hard with the trajectory display and predictors, and you'll get the range to site on the PFD and the call-out to pitch down.

Come to think of it, MECO actually won't be initiated automatically if you're not at the correct alpha - so when flying CSS you can delay MECO by not pitching down when commanded. I knew there was some logic to the code...

You can /probably/ also initiate MECO yourself using the cutoff buttons and by-passing the MECO targeting, but that'll require to transit to MM 602 and activate the Aerojet DAP by hand - and you'll have to separate ET, close umbilical door and do the MPS fuel dump quickly... so there's something said for using the automatic targeting even if it's not perfect.
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Re: Space Shuttle

Postby GinGin » Tue Jul 25, 2017 6:05 pm

It's amazing how close to reality it is.
All the step, different transition and guidance. Looks like I am in a NASA fixed base simulator :)

I am gonna give it a try fully manual so. With a good joystick, it should be ok to handle the really critical Nz hold.
I am wondering, for the max G before breakout, you took max Contigency G of 4.1 G and max speed estimated before LOC of 470 kt or is it normal operations value ( around 3 G and 330 kt if I remember well)

It's indeed quite frightening how fast everything happens after MECO, MPS dump, Umbilical door reconfiguration,DAP aerojet transition, and already in Alpha recovery and Nz hold in less than a minute. ( Should we also dump the FWD RCS propellant ?)

Gonna give it another thorough test this week end, and I am very tempted for a 2EO Green abort to Bermuda also, I have good souvenir of this one :)
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Re: Space Shuttle

Postby GinGin » Tue Jul 25, 2017 6:10 pm

A friend had a weird visual effect on boosters exhausts in the SRB and no Exhaust for SSME, any hints ?

Image
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