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Re: Space Shuttle

Postby GinGin » Wed Oct 11, 2017 6:28 pm

You do realize that I'm still hunting them


I know, it wasn't a critic !

Correct words would have been : it's impressive to have so few bugs compared to the task accomplished.
I wouldn't have think it possible to accomplish that level of realism

It was just to let you know what I found, wrong formatation ;)



Failure of 4 GPC, everything polled by the GPC 1, crazy dangerous situation xD

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Re: Space Shuttle

Postby wkitty42 » Thu Oct 12, 2017 6:26 pm

GinGin wrote in Mon Oct 09, 2017 1:47 pm:Image

STSPlus! haven't seen that in the wild in a while... hated when david ransom passed to the next realm...
"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

Postby Thorsten » Fri Oct 13, 2017 6:52 am

I save a situation (eg I am in stable orbit) I close and I open again FlightGear and the Shuttle. I resume the situation I had saved and the MET is at zero.


I'm currently adding IDP and computer memory status to the saved state, and I took the opportunity to look at MET as well. I did see MET properly resumed.

(In my test, I started with the --orbit flag which sets MET to 8 minutes something, then re-configured all the displays loading SM into GPC 3, saved the state - at that time MET was 12 minutes 30). Then I quit FG, re-started with --orbit, selected the resume option, and I saw MET jump from 8 to 12 minutes 30 as expected.)

So I need more information then to tackle this, it works fine for me.
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Re: Space Shuttle

Postby Thorsten » Fri Oct 13, 2017 6:54 am

STSPlus! haven't seen that in the wild in a while... hated when david ransom passed to the next realm...


Admittedly it's a nicer display than what we have, showing more stuff for starters... if someone wants to have a go re-doing the groundtrack map, he's most welcome, the current design is my first (!) canvas experiment and the code is pretty crappy because I didn't know any better.

But it's waaay down on my priority list to replace it...
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Re: Space Shuttle

Postby wkitty42 » Fri Oct 13, 2017 4:04 pm

@Thorsten: what you have looks fine... it is pretty much the same thing as Orbitron uses... Orbitron replaced STSPlus for many folks but it is now apparently abandoned... IIRC, the author wrote it while in high school or similar...
"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

Postby GinGin » Sun Oct 15, 2017 11:05 am

Very nice for the save.
Is it possible to export the save state to share with others, like to create a starting point for a deorbit prep scenario?

I will run some tests next week
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Re: Space Shuttle

Postby Hooray » Sun Oct 15, 2017 11:17 am

if someone wants to have a go re-doing the groundtrack map, he's most welcome, the current design is my first (!) canvas experiment and the code is pretty crappy because I didn't know any better.


Stuart recently added a new type of MapStructure layer for overlays - and we do have support for plotting ground tracks (e.g. the flight path history), we could also tell the same drawing routines to render a future state vector - as logn as we pass a vector with positions to it. Which is to say, that it may not be that far-fetched to use the MapStructure system to extend/redo the orbital mode. That would also mean that the display itself would become available to other aircraft, and that it could be added to other charts/displays much more easily.

Regarding saving/loading flights:
I think Thorsten mentioned elsewhere that the shuttle team created their own scripted load/save helpers - otherwise, the replay/flight recorder system (fgtape) would be the most likely candidate - however, it's pre-dating the shuttle by several years, and was considered fragile even for conventional airplanes - so not sure if it's even feasible to consider using that for spacecraft like the shuttle - it may need to be extended to do so.

Apart from that, the real issue is that anything involving computation of values (flight dynamics, autopilot, route manager, scripted systems and so on) must provide a mechanism/interfacing point to deal with resetting its systems to a new state vector - imagine resetting all systems to fly an approach. Basically, there is no sane way to support this in a generic way - aircraft developers must be made aware of what the user is trying to do, so that they can shut down/suspend their systems and re-init everything according to the desired state vector (situation/configuration).

The only thing FlightGear as a platform can do, is provide "signals" and building blocks to encode such state vectors - other than that, this is the primary reason why resetting any aircraft in FlightGear a few times in a row is likely to cause a crash, but also the reason why saving/loading and continuing flights is usually not possible at all.

Basically, each and every subsystem running at any point in time would need a way to respond to a shut-down/reset or save/load "signal" and do internal housekeeping - while this is something that David Megginson (creator of the property tree and subsystemMgr implementation in FlightGear) originally designed, it was never actually used or carefully enforced to be adopted for new systems - which is also the reason why even new subsystems added recently, don't support a proper reset/re-init.
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Re: Space Shuttle

Postby Thorsten » Sun Oct 15, 2017 11:40 am

Is it possible to export the save state to share with others, like to create a starting point for a deorbit prep scenario?


It is written to a human-readable file - you can edit, copy or share the file as long as you know where to find it.

And there lies the rub, because for security reasons, very few directories are writable from Nasal, so it gets saved into the same folder as all the other autosaved aircraft properties, which is a hidden folder for basically all OS. Under Linux it's .fgfs/aircraft-data/SpaceShuttleSave/save?.xml I'm not even sure I know where to find it on Windows.


But actually you can start with SpaceShuttle-ISS for a deorbit prep and specify lat, lon and heading to get into a particular orbit (if you don't mind ISS around while you do your burn).
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Re: Space Shuttle

Postby Hooray » Sun Oct 15, 2017 3:38 pm

for security reasons, very few directories are writable from Nasal, so it gets saved into the same folder as all the other autosaved aircraft properties, which is a hidden folder for basically all OS. Under Linux it's .fgfs/aircraft-data/SpaceShuttleSave/save?.xml I'm not even sure I know where to find it on Windows.


If I am not mistaken, $FG_HOME/Export should work for all platforms - and I think you can add a menubar entry to open it by using a binding along the lines of:

Code: Select all
var path = getprop('/sim/fg-home') ~ '/Export';
fgcommand("open-browser", props.Node.new({ "path": "file:///"~path }));
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Re: Space Shuttle

Postby GinGin » Mon Oct 16, 2017 7:34 am

Ok thanks for the info.
Good idea for the ISS scenario, I,can start overhead KSC or the landing base, then planned the landing two orbit laters, roughly 3 hours before deorbit burn overhead Indian Ocean.

If I am not mistaken, with an inclinaison of 30 degrees, max cross range built in two orbits should be around 500 Nm.

I was wondering, how did you create those start points, i.e. Launch, orbit , iss, etc ?
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Re: Space Shuttle

Postby Thorsten » Mon Oct 16, 2017 7:41 am

Basically there's a function which, dependent on state, switches the various systems on and off, computes a reasonable state vector and applies that.

It's somewhat easier as the save/load procedure because the possibilities are more restricted, but it's still complicated, the Shuttle doesn't like to be pushed into a certain state, so there's plenty of auxiliary routines which suppress transient errors.
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Re: Space Shuttle

Postby Thorsten » Tue Oct 17, 2017 7:32 am

After tracking down and eliminating a couple of issues, I finally managed to fly a complete TAL under BFS today (the trick is that when BFS is engaged, the major mode info should not be taken from PASS any more but from a different variable - but only for BFS-relevant pieces,... that caused a number of issues after the OPS transition).

And yeah, I did the entry by hand to stay in character (BFS doesn't have automated entry). :mrgreen:
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Re: Space Shuttle

Postby GinGin » Tue Oct 17, 2017 3:40 pm

Nice one :)
I will test that for sure.

No yaw jet BFS High energy TAL now? ahah
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Re: Space Shuttle

Postby GinGin » Wed Oct 18, 2017 9:57 am

@Thorsten: Idea to start at ISS Scenario Start point for Advanced Deorbit procedure is a very good idea.

I was wondering if it would be possible to have two or three changes to help when starting with ISS scenario, like :

TACAN, MLS, RA off
DPS in correct Configuration like after Post insertion reconfig


I made some tests on save/resume options.
It works well for Saved DPS config, MET time, well done

Some switches position are not saved ( TACAN, MLS, RA ) I will do some more tests :)


I updated the wiki with the brand new DPS layer http://wiki.flightgear.org/Flying_the_Shuttle_-_Launch_And_Post_Insertion_Advanced
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Re: Space Shuttle

Postby GinGin » Wed Oct 18, 2017 2:18 pm

I saw many changes to BFS, awsome work

True display between PASS and BFS for Spec 51 for example that vary a bit

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So cool
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