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Old 12-19-2017, 05:12 PM   #1216
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Originally Posted by DaveS View Post
 It looks close but it should be fine. Here's a photo of the aft shot by one of the crew members of ISS Expedition 22 during the RPM of STS-130. Note the small clearance of the ROME and the right stinger (this was the informal nickname for he ARCS pods).

It also seems like we have the on-orbit stow position of the SSMEs wrong based on that photo. At least for the lower two engines. Ours currently creep together in yaw but in that photo, it seems yaw remains at 0.

---------- Post added at 04:36 PM ---------- Previous post was at 04:21 PM ----------

Here's another photo showing the ROMS pod of Atlantis before it was removed for maintenance during the post-Columbia standdown in 2003: https://www.dropbox.com/s/zj5956gdeq...d2589.jpg?dl=0

As you can see, there's plenty of clearance. Here's a screenshot from AC3D showing a similar angle: [urlhttps://www.dropbox.com/s/kxwjatz6wcje14n/AC3D_ROMSPOD.jpg?dl=0[/url]

I think this quote from Obi-Wan Kenobi is appropriate here: "Your eyes can deceive you. Don't trust them."
But is it in the correct place (Zo 492) according to the diagram?
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Old 12-19-2017, 05:41 PM   #1217
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Originally Posted by GLS View Post
 But is it in the correct place (Zo 492) according to the diagram?
That has now been adjusted.

---------- Post added at 06:41 PM ---------- Previous post was at 06:27 PM ----------

I checked in an updated Atlantis_defs.h with new OMS reference positions. They seem to be holding with the correct DIR parameters.
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Old 12-20-2017, 12:35 PM   #1218
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I'm +/- finished with the "hardware" side of the OMS TVC and basic SOPs to interface with it. Now comes the difficult part of changing the existing software to use the new ways.
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Old 12-20-2017, 01:11 PM   #1219
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 I'm +/- finished with the "hardware" side of the OMS TVC and basic SOPs to interface with it. Now comes the difficult part of changing the existing software to use the new ways.
Does this mean the actual physics of the OMS? That should include the nozzle glow as that's how the nozzle cooling works, by radiation.
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Old 12-20-2017, 02:13 PM   #1220
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 Does this mean the actual physics of the OMS? That should include the nozzle glow as that's how the nozzle cooling works, by radiation.
Just working TVC (but might get on/off control relocated). No valves or anything else for now.
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Old 12-22-2017, 01:07 AM   #1221
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Are the OMS engines meshes really at the correct angles?
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Old 12-22-2017, 03:44 AM   #1222
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 Are the OMS engines meshes really at the correct angles?
They should be. Why? I did a couple of test burns using your DIR parameters with the corrected positions and they held nicely. No RCS wraparound activity whatsoever. Only thing was 2 fps radial residual at the end of each burn.
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Old 12-22-2017, 11:43 AM   #1223
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 They should be. Why? I did a couple of test burns using your DIR parameters with the corrected positions and they held nicely. No RCS wraparound activity whatsoever. Only thing was 2 fps radial residual at the end of each burn.
I'm seeing a difference in pitch between the animated nozzle and the gimballed thrust vector (exhaust texture). But then this thing currently needs to gimbal the nozzles pretty much all the way down (~5.7) to point to the c.g., which doesn't seem right.
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Old 12-22-2017, 11:51 AM   #1224
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First question: How do you measure the angles?
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Old 12-22-2017, 11:52 AM   #1225
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Originally Posted by GLS View Post
 I'm seeing a difference in pitch between the animated nozzle and the gimballed thrust vector (exhaust texture). But then this thing currently needs to gimbal the nozzles pretty much all the way down (~5.7) to point to the c.g., which doesn't seem right.
I just checked, 15.5 pitch and 6.7 yaw. That is the correct angles right?

---------- Post added at 12:52 PM ---------- Previous post was at 12:51 PM ----------

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Originally Posted by Urwumpe View Post
 First question: How do you measure the angles?
That's a good question, I measure it along the nozzle centerline.
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Old 12-22-2017, 11:58 AM   #1226
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If I see the diagram here in low quality correctly:

-15.8 pitch
+/- 6.5 yaw
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Old 12-22-2017, 12:16 PM   #1227
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 I just checked, 15.5 pitch and 6.7 yaw. That is the correct angles right?
The diagram says pitch 15.82444 and yaw 6.5.

---------- Post added at 12:16 PM ---------- Previous post was at 12:09 PM ----------

Quote:
Originally Posted by Urwumpe View Post
 First question: How do you measure the angles?
The directions I'm using came from "forcing" the vector compoments to have the null angles (see above) between them. Doing 2 rotations makes a vector that only matches one of those angles. Here it is: (+/-0.105128, -0.370911, 0.922699).

The nozzle is animated in the standard way, and the thrust vector direction is rotated using 2 rotation matrixes (because the rotation axis are slightly tilted) that use the same parameters fed to the animations.
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Old 12-22-2017, 12:47 PM   #1228
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 The diagram says pitch 15.82444 and yaw 6.5.
I have checked in an updated orbiter mesh that has the OMS nozzles at those angles. I measured the angle between the c.g location and the pitch angle of the OMEs, and it comes out as a difference of 0.2.
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Old 12-22-2017, 01:24 PM   #1229
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Remember, when you do the thrust vector rotations, that the yaw axis should not be rotated with the pitch axis. Simply multiplying two rotation matrices should be wrong.
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Old 12-22-2017, 03:00 PM   #1230
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How sure are we that the ORBITER_CG is correct? With it applied to the mesh c.g., the OMS engines end up at a ~30 angle instead of the expected ~15. Could it be that the c.g. was calculated assumming the nose is Xo=0, instead of Xo=236?
BTW: the (0, 0, 0) point in the mesh is what exactly in (Xo, Yo, Zo)?

---------- Post added at 03:00 PM ---------- Previous post was at 02:57 PM ----------

Quote:
Originally Posted by Urwumpe View Post
 Remember, when you do the thrust vector rotations, that the yaw axis should not be rotated with the pitch axis. Simply multiplying two rotation matrices should be wrong.
This is what I did:
Code:
	MATRIX3 mrot = rotm( axisP, pitch * RAD );
	dir = mul( mrot, dir );

	mrot = rotm( axisY, yaw * RAD );
	dir = mul( mrot, dir );
The animation has the yaw as the parent for the pitch, same rotation parameters.
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