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Orbiter Web Forum A forum for general Orbiter-related comments and discussion. Post your questions about Orbiter and addons in the appropriate forums below. Upload your Orbiter screen shots to our gallery HERE!

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Old 02-01-2016, 08:21 PM   #1006
indy91
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Quote:
Originally Posted by kuddel View Post
 Sorry for not beeing exact enough

What I wonder is:
What (external) influences make the DAP (the controller) change the gimbaling?
I think that this is a kind of control-loop, right? So what are the "errors" that make the controller react to compensate them?

Thanks in advance,
/Kuddel
Yes, it's a quite complicated control loop with a digital filter that can even compensate for propellant sloshing and bending of the spacecraft (relevant for the docked CS/LM configuration).

During a long burn such as the LOI there are basically three reasons for the gimballing. Firstly the DAP will try to point the engine through the center of mass of the combined spacecraft. Before the maneuver, trim angles are set into the computer to help it find the right gimbal angles at ignition, but these trim angles are never perfect. Also, the center of mass changes during the burn depending on how much fuel and oxidizer is left.
Secondly the DAP will try to align the thrust vector with the desired direction of acceleration based on the parameters set into the computer before the burn.
And thirdly, during longer SPS firings, the DAP will periodically recalculate that thrust direction with the help of accelerometer readings to cancel out the errors accumulated by previous thrust misalignments. The steering concept used is called Cross Product Steering.
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Old 02-01-2016, 11:06 PM   #1007
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Thanks indy91! That was what I wanted to know
So NASSP *does* simulate (fuel-) mass shift...great! Do you add some "randomness" to those (error-) input values?
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Old 02-01-2016, 11:26 PM   #1008
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Well, what I explained above was mostly about the dynamic behavior the AGC expects, mass shifts are not currently simulated, but might be in the future. We might make NASSP more realistic with changing center of mass, if it is possible. However, as you can see in the video, the TVC DAP is working and it is using the historically correct parameters, so no hurry for these kind of changes.

One point with regards to the SPS gimballing is however kind of dynamically changing already. Basically, the neutral setting of the SPS is angled 2 in pitch and 1 in yaw. But because the CSM is a perfect point mass with the center of gravity right in the center of the spacecraft, the SPS engine in NASSP has a slightly offset position so that it points through the center of gravity in this neutral setting. Now, with the docked Lunar Module, the SPS engine and the CSM and the LM are not on a straight line because of that. So in the docked configuration, the SPS doesn't gimbal around 0 but depending on the masses of the CSM and the LM.
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Old 02-04-2016, 08:02 PM   #1009
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Orbiter 2015 4k test video and upload:


Using Orbiter 2015's frame capture mode, took 24 minutes to get 3000 frames at 100fps, blended to 30fps for 4k upload.
I don't have a 4k monitor, but I used Nvidia's DSR feature to upsample to 4k.
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Old 02-23-2016, 11:44 PM   #1012
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Default Hadley Approach with New Low Altitude Microtextures for D3D9Client and Orbiter Beta

To give you an impression of the new low altitude microtextures for D3D9Client Beta 19d with Orbiter Beta r.50, here's a mp4 video of my landing approach at moon's Rima Hadley.

>>> link to 10-minute landing approach MP4 video <<<




See Orbiter Visualization Project / D3D9Client thread #3546
Enjoy - Rob

Last edited by rstr; 03-15-2016 at 12:41 PM.
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Old 03-17-2016, 03:30 PM   #1015
Donamy
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Brought a tear to my eye. Thanks !

Also a thanks to SiameseCat and David413.
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Old 03-18-2016, 07:34 AM   #1016
IronRain
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Another great video.
Excellent choice of music btw!
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Old 03-20-2016, 12:49 PM   #1017
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Also rseferino, I respect your decision to remove moon hoax troll comments from your page.
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Old 03-28-2016, 05:06 AM   #1018
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This is from the Moon, I was thinking of posting the whole trip but I did an inverted aero break which lasted along time so I just uploaded from a save point where I performed normal reentry. Nice scenery between 3:40 & 4:40. This is the current lastest Beta of Orbiter and D3D9Client.
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Old 03-28-2016, 06:16 AM   #1019
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Spectacularly beautiful jroly, but you should probably retract your radiator prior to re-entry.

If it were an XR, you would be dead.
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Old 03-28-2016, 06:53 AM   #1020
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Originally Posted by boogabooga View Post
 Spectacularly beautiful jroly, but you should probably retract your radiator prior to re-entry.

If it were an XR, you would be dead.
It was an XR1, the radiator can withstand 400-500 degrees, the reason I had it deployed was I just previously performed an inverted aerobreak which lasted a long time and the internal systems needed cooling.
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