Space Shuttle Ultra 1.25 Revision B development

[SPASE_1976]

Ok, lets gather all identified bugs and development tasks by the development team here.

+++ Please don't use this thread for reporting bugs in SSU 1.25 or asking for support, I will erase such posts without thinking or care. +++

How can you do that ? you are not a moderator

 

[tblaxland]

How can you do that ? you are not a moderator

Actually, the addon developer forums each have their own moderators in addition to the overall forum mods. It helps to reduce our workload . Addon developer mods have no moderation privileges on the rest of the forum, the privileges only apply within their own sub-forum.

EDIT: Urwumpe, apologies for hijacking the thread. Feel free to delete this post

 

[DaveS]

How can you do that ? you are not a moderator

He is, here in the SSU sub-forum, just like I am. And this is the final post on the matter as this thread is for us SSU developers only to discuss further developments.

 

[tblaxland]

The maths for the KU gimbals is attached. It could be simpler using rotation matrices, but it should work anyway. You will need to do your own research on the direction of the alpha axis and the beta axis for alpha=0 (should not be hard though). EDIT: I've also attached a picture marked up with the axes to help you.

 

[Urwumpe]

Should go to be implemented that way, though I am not exactly sure it also reacts properly on the pole singularities of the antenna. Makes at least sense to me...

 

[tblaxland]

Should go to be implemented that way, though I am not exactly sure it also reacts properly on the pole singularities of the antenna. Makes at least sense to me...

The singularities only occur when vectors a and t are either parallel or anti-parallel. Just check for that by calculating the beta angle first. If it is within its range of motion (2 to 164 deg) then you are safe to calculate the alpha angle, otherwise declare a beta-out-of-range and do not move the gimbals at all (beta and alpha).

EDIT: You may also have an issue (presumably it is a real life one) near alpha=0. Slight changes in the target direction could cause the required alpha angle to oscillate between just greater than 0 and just less than 360. I'm not sure how they handle that IRL, to stop the antenna slewing all the way around. Some sort of time delay to give the antenna a chance to lock back in before it decides to move? Also, I forgot to mention that the formula for alpha will give a result in the range -180 to +180. You will want to normalise that to 0 to 360 (the zero direction remains the same) to match the real life operation of the alpha gimbal.

 

[DaveS]

Checked in an important change to the Ku antenna deploy/stow rotation angle. After some measurements, I found that it was seriously off. The previous value was 118°s while the now implemented and correct value is 150°s.

This should lead to a correct angle WRT to the orbiter X-axis as outlined in the SCOM Comm section(67°s).

 

[Urwumpe]

Are you sure on 150°, it sounds like a too smooth number for what I saw in the drawings...

 

[DaveS]

Are you sure on 150°, it sounds like a too smooth number for what I saw in the drawings...

You might be thinking of 113°s, but that isn't around the pivot point of the deployed assembly. I checked with a video of the DA being deployed at the beginning of STS-95 against a view of our DA and the deployed angle now looks a lot better.

 

[Donamy]

The default angles in Orbiter for the KU are:

0.599027,-0.759358,-0.254051 Beta
0.22346,-0.124124,0.966778 Alpha

 

[Donamy]

Do you need the points of rotation ?

 

[Urwumpe]

Do you need the points of rotation ?

I already have them, I also already defined the animations long ago. The external stuff of the Ku Band antenna is already done.

 

[Donamy]

The animation angles were changed a few days ago.

 

[Urwumpe]

The animation angles were changed a few days ago.

Isn't the mesh and the stored position the same?

 

[DaveS]

The animation angles were changed a few days ago.

Yes, a new Ku antenna mesh and texture was checked in by me a few days ago. This Ku now have the correct appearance like one attached to this post of Challenger's Ku antenna.

 

[Urwumpe]

OK, must have missed this upgrade. Then I need to fix the animations once I have the new meshes.

 

[DaveS]

Any updates on the Ku antenna? Meanwhile I'm working on the VAB interior structure. Not the same structure mesh as previously shown in my blog entries, but a brand new one, this time made in AC3D.

The status on that is that both the east High Bays(integration cells 1 and 3) are almost done. Once the east bays are complete, I'll do the west bays.

 

[Urwumpe]

Any updates on the Ku antenna?

No. Had to cut my orbiter time this weekend for lots of housekeeping work. Will not work on it this weekend, I am away for a wedding, but I hope I can find some more time for SSU in the middle of August.

 

[DaveS]

No. Had to cut my orbiter time this weekend for lots of housekeeping work. Will not work on it this weekend, I am away for a wedding, but I hope I can find some more time for SSU in the middle of August.

How far did you manage to get? Anything you can check in? Even the manual slew mode would be a huge step forward.

 

[Urwumpe]

How far did you manage to get? Anything you can check in? Even the manual slew mode would be a huge step forward.

Not that far yet, I can just trigger a change of the orientation to hard coded values. Even with bypassing the GCIL stuff, the aft panels around the KU band antenna would need a while more until you can use them.