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Re: Space Shuttle

Postby Thorsten » Wed Nov 21, 2018 5:36 pm

I'd suggest airport keep for the pads - it looks visually similar (it's clearly managed in reality) and we an make it rather detailed.
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Re: Space Shuttle

Postby GinGin » Wed Nov 21, 2018 6:48 pm

Heya :)

I love those new trees, thanks lego

Image





Alright, some more tests there.

Direct insertion, 29 ° of inclination
New map is really usefull and neat, old still useful for re entry range and landing site.

Image




Alright, after MECO, orbit quite elliptic ( 0.4 ) of 153 by 67 Nm

Shape moved a lot till passing 100 Nm, and it stabilized to e=0.3 and 122 by 68 Nm.
I have the feeling that below 100 Nm, atmosphere is still influencing the Shuttle noticeably


Then I took the state vector from that stable orbit to find a Deorbit solution for AOA to KSC




I didn't inserted TIG and waited the correct TIG to burn, REI OPS 3 matched closely the LEO one

Image


After burn REI coherent

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Unfortunately, REI happened around 4000 Nm instead of the forecasted 3500 ish Nm. I was a bit short with a steep angle

I made tests on motr normal orbit, almost circular and above 100 Nm. REI forecasting works normally there.

it has to be a lot of complex calculations behind a REI forecasting concerning high e and low level orbit like AOA :D



Also, I was trying failure of Freon Loop ( found an amazing doc about the case of AOA after Meco due to dual failure of Freon, with thermal shedding etc, next scenario ahah)
I remarked that when I switch off Freon Loop without turning off FES and Hi Load, nothing really happens


Also conerning Loop 1, when I switch to AC 2 , freon flow becomes negative, weird


Image

Image



that's it for today :)

I am still amazed by the precision of LEO tools for AOA and Peg 4. I use mainly AOA target from AOA fdf, I tweak just a bit the theta value, but man, it is so close to the real stuff ;)



PS: Emer red light like in Submarine xD cool

Image
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Re: Space Shuttle

Postby Thorsten » Wed Nov 21, 2018 6:52 pm

I have the feeling that below 100 Nm, atmosphere is still influencing the Shuttle noticeably


Yes. Somehow 85 miles in FG is not a particularly safe orbit at all. Which would potentially explain the mismatch in REI - LEO targeting doesn't know about atmosphere drag (and the magnitude of that drag depends on Shuttle attitude anyway).

Not really sure what to do about that.

Also conerning Loop 1, when I switch to AC 2 , freon flow becomes negative, weird


It's probably 'switch position times nominal flow' without taking into account that it's a three way switch... I'll look.
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Re: Space Shuttle

Postby GinGin » Wed Nov 21, 2018 7:07 pm

Yes. Somehow 85 miles in FG is not a particularly safe orbit at all


Aah Ok, a new Karman boundary :)

Well, it makes sense yes. I usually take 300 ish Nm of Margin for REI in those conditions, and it works nicely.
But yes, it seems complicated to integrate those stuff in the Leo Tools.
It would be possible to change it in FG ? It is coded in the general FG code?






It's probably 'switch position times nominal flow' without taking into account that it's a three way switch... I'll look.


Cool, thanks !
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Re: Space Shuttle

Postby wlbragg » Wed Nov 21, 2018 9:00 pm

Emer red light like in Submarine xD cool

You found it. It's been available in the debug menu since early on, I finally got around to adding it to the GUI. :)
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Re: Space Shuttle

Postby eatdirt » Thu Nov 22, 2018 10:02 am

Thanks Gingin, got it for Delta state updates.

Back from 3000nm of HA, still alive in White Sands, the new trajectory map is super useful: 4 atmospheric gentle braking + 1 entry from HA=1100nm straight in to see if that works.

That works, but it looks like an abort more than a re-entry!

A few minutes before that shot, I was confident to get onto the nominal trajectory, but a lot of kinetic energy was there :)

Image

Then took CSS to bank as soon as I could and switched back to AUTO, 75 degrees bank angle, crew black out:

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Everyone, crew and shuttle still there:

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Ready for HAC and landing:

Image


Afterwards, I actually managed to destroy the gears, you won't get any shot for the landing then :) But I'll be getting my joystick next week, hopefully that would be helpful for night landing!

Cheers,
Chris.
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Re: Space Shuttle

Postby wlbragg » Thu Nov 22, 2018 6:10 pm

Lessons learned...

Once I figured out that the darkmap alpha channel is supposed to be completely transparent, not opaque, things started to work out better.
I'm sure there was a reason for that but in my mind I had it that the opaque data on the texture would be what was darkened. I guess it doesn't really matter as the entire object is to be darkened regardless of it's mapping.

If you ever plan on using lightmaps it is a must to not take shortcuts when texturing a mesh. Thing like overlap boundaries matter.
I am going to apply the darkmap/lightmap effect on all objects in the bay. The airlock was what I was referring to, it used a small 256x256 texture and then mapped the mesh to something way bigger 1024x???? so that it kept the resolution of the smaller texture everywhere. But you can't do that and apply any kind of useful lightmap. So if you notice a change to the resolution of the airlock, that is why. I'll do the best I can but I want to keep the texture size down.

Oh, and Raytracing in Blender is far superior, don't bother using approximation unless texture resolution is an issue.

At least I am making some progress.

Here is pretty much the final versions of the airlock and oms kit.

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Re: Space Shuttle

Postby legoboyvdlp » Thu Nov 22, 2018 8:00 pm

Image

@Thorsten,
bright green = grasscover
dark green = forest (not very tall trees, but fairly dense)?
dark blue = water
pale green = launchpad (keep)
yellow / red = vmap landclasses (drycrop, grassland)

you could map drycrop to be the mixed shrubs / small trees / grass?

I have to do the part north of here and also west / north-west a bit.
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Re: Space Shuttle

Postby Thorsten » Fri Nov 23, 2018 8:10 am

you could map drycrop to be the mixed shrubs / small trees / grass?


I suspect we do this currently (?)

Pad mapping looks very promising - this is going to be great!
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Re: Space Shuttle

Postby eatdirt » Fri Nov 23, 2018 9:52 pm

Hello guys,
got again the payload escaping today, maybe I am missing something in the procedure?

Here the series of snapshots, at about 5-10 seconds of intervals for the first ones, and about 1 minutes between the first and last.

Ready, Steady:
Image

Go!
Image
Image
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Hasta la vista, baby!
Image

Zero rates, free modes, no FES, drain valves closed:
Image

Dunno what I am missing, but that makes catching the SPART..., Van-Allen probe again a serious challenge :)


Cheers.
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Re: Space Shuttle

Postby wlbragg » Fri Nov 23, 2018 10:19 pm

KU Antenna getting texture and lightmap face lift.

Image

I haven't verified what the deployed version look like yet.
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Re: Space Shuttle

Postby GinGin » Fri Nov 23, 2018 10:35 pm

Sum up of my last test :

https://forum.flightgear.org/viewtopic.php?f=19&t=35048



@legoboyvdlp: Very promising indeed :)

@Wayne: Awsome work, that OMS kit looks very neat

@EatDirt: Ahah, you lost another one xD Happy Nasa. I have to try your stuff with aerodynamic breaking.
I also need to spend more than one orbit in space also now, back to more nominal situations



@Thorsten: Some quick return on failure management.
Love it, I played a lot with the jsb stuff :)

However, I didn't get the APU Fault automatically has I would have expected, maybe I did something wrong there?

Image



Also, I turned off both Freon Loop, and Evap Out T was decreasing instead of getting higher, quite weird

Image



Nice work with the new trajectory map, we almost have a small MCC there :mrgreen:

I was wondering : what is the mathematic formula behind the Horizon option? It could help me to fine tune the visibility when I don't use the Earthview.
Just getting 32 Go of ram, so I might try more than a million km to see :)



Also, concerning REI range for AOA, I found that with Perigee around 20 Nm ( not too steep path), prediction was fairly accurate.
Need to test more and more :)
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Re: Space Shuttle

Postby Thorsten » Sat Nov 24, 2018 6:45 am

But yes, it seems complicated to integrate those stuff in the Leo Tools.
It would be possible to change it in FG ? It is coded in the general FG code?


If we know what the issue is, we can always fix it. It might well be that the Shuttle lift/drag curve parametrization are used outside their validity at 85 miles altitude (the dynamics is probably no longer fluid-like) - generally I suspect JSBSim itself is reasonably well tested also against space problems.

The issue is that I have not seen solid data for that region (even wind tunnel data rarely goes above Mach 10 - for obvious reasons), and to make a blind change based on gut feeling seems a bad idea.

So we'd have to settle on some characteristics / dynamics which we aim to match and then I'd proceed to alter the L/D curves to reduce their effect beyond a certain altitude/ density.

got again the payload escaping today, maybe I am missing something in the procedure?


Well, is this a one-time thing, or a constant drift (i.e. if you step on the THC to immediately cancel the relative motion - does it stay canceled?)

If it's a drift like I suspect, the reason is probably the rather unusual nature of your orbit. FG is not actually able to run flight dynamics for secondary objects, so we have to do this ourselves in the Shuttle code, but there we have the restriction that we have a rather coarse time resolution because everything updates at framerate - hence there's some clever approximations being used (basically it 'borrows' most of the gravity field computations from the Shuttle).

I'm guessing that works better for a near-circular low orbit...

Can you try satellite catching in lower orbits first?

However, I didn't get the APU Fault automatically has I would have expected, maybe I did something wrong there?


Try

Code: Select all
<section-defined type="bool">true</section-defined>


That'll actually make it valid. :mrgreen:

Also, I turned off both Freon Loop, and Evap Out T was decreasing instead of getting higher, quite weird


Can you describe in more detail what you did? What were the evaporators set to?

I was wondering : what is the mathematic formula behind the Horizon option? It could help me to fine tune the visibility when I don't use the Earthview.


Assuming a spherical Earth, it's

d = sqrt(2 * R * h + h^2)

with h the altitude above ground and R th Earth radius.
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Re: Space Shuttle

Postby GinGin » Sat Nov 24, 2018 2:30 pm

Alright , forgot the bool.
Thanks for the formula, so around 2000 km of visibility for 400 km orbit

Concerning the rei, I will do some thorough test with different conditions and values to see that .


For Freon , when I switch of the freon pumps, I let the fes active with high load. T decreases , I guess it should be the opposite as there is no flo anymore .


When I let the pumps on and switch off Fes, Evap out T is increasing as excepted

When I switch pumps and Fes, temperature is increasing but slower than with Freon pumps on
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Re: Space Shuttle

Postby Thorsten » Sat Nov 24, 2018 3:23 pm

For Freon , when I switch of the freon pumps, I let the fes active with high load. T decreases , I guess it should be the opposite as there is no flo anymore .


You're measuring temperature at the end of the evaporator stage. If you have flow, there's warm freon going into the evaporator, being cooled a bit and exiting. If you have no flow, the evaporator is essentially cooling itself, there's no warm freon coming in, so my understanding is that temperature at the evaporator should decrease but temperature everywhere else in the freon system should increase.
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