SSU Development Thread (2.0 to 3.0)

[GLS]

That the struts doesn't line up should be correctable by adjusting the attachment points on the FWC SRBs.

I'll add the FWCs to the list of things that need fixing.

Actually it's not just the FWCs but both types of SRBs (or the ET).

I'll create some tickets for this (what I should have done in the first place).

 

[DaveS]

Ticket#72 fixed and closed in revision 1795.

 

[DaveS]

How is the code review coming along? What is the hold ups for a release besides the mesh issues?

 

[DaveS]

I'm pretty much done with the updated orbiter mesh, except for one major ticket item: The wings. I have tried for days now trying to get the correct wing profile without much success. I'm not sure what I should do.

Except for the wings, only resizing of the Ku band DA, RMS, Ext A/L/ODS and OBSS remains along with a few texture tweaks.

 

[DaveS]

Some progress. The only problem I have now is the section of the wings that interface with the lower FWD fuselage half.

 

[GLS]

My FPGA project for a class worked perfectly on the first try, so I found some free time this weekend and added 2 australian emergency landing sites to SSU, so our aussie users can now land the shuttle down under.

 

[DaveS]

This for the ascent performance problem we have been having for a while: I got quite the insight today with the suspicion that SC3 doesn't add the mass of any attached children so I decided to add the total mass of the Centaur G Prime as fuel mass to the CISS and that made a world of difference.

The end result was that I couldn't make orbit no matter what. The perigee was always negative as what I suspect was the result of a low-level cut-off rather than a guidance cut-off.

So the performance is really there, our GNC and MPS is very tight and accurate. So it seems like we need a way to switch orbiters, in terms of empty mass as we're right now hardcoded to the empty mass of Columbia at the time of her rollout in 1979 and there's no way to get her with the STS-61G loaded mass into orbit.

 

[GLS]

The ascent performance (in general) is still not 100%, and I suspect it's because the SSMEs have a different ISP for different power levels. I did some research but couldn't find enough info on that to do anything about it.
For the Death Star missions, mass is probably the most critical thing we have to nail, in order to get them correctly into orbit. And that's why, a few weeks ago, I suggested that we need to "stop" after this release and get some things changed to have more control of the mass and other parameters (cue the Mission Editor discussion).
BTW you can check if there was a low level cutoff in the log file.

 

[DaveS]

BTW you can check if there was a low level cutoff in the log file.

Confirmed, LOX low-level cut-off at T+8:03.

 

[Donamy]

I think it's close enough for our needs. Do we expect a release soon ?

 

[GLS]

(moving the discussion on the MECOTool and the trajectory at MECO from the Centaur thread to here)
So, I remembered the computer won't explode for trying stuff, so I made a copy of the MECOTool folder and tried the conversion... and it worked well! Changed the Earth radius value and got a set of MECO targets, and it's better but not good enough. The perigee is still too high (66 vs 55Km), and some quick flight path angle calculations at MECO show that the AscentGuidance is producing a shallower angle.
I'm beginning to think the "ditching" of the MECOTool was premature...

 

[DaveS]

MECOTool needs to be changed so it can be compiled with the express editions of VC++. So far the only hard stop for that I have found is the help compilation. If that could be removed, it would be great.

 

[DaveS]

Wings are done along with a new smoother and more accurate payload bay. I thought I had fixed the FWD fuselage star trackers but that turned out not to be true. I have all but given up on them.

 

[Donamy]

How did they get broken ?

 

[DaveS]

How did they get broken ?

It's the same smoothing problem as earlier. It's the -Y star tracker that's the issue. If a new FWD fuselage could be created from these X-sections, it would be great.

For the size of the star trackers, note their relative sizes to the windows in this photo of Atlantis:

 

[Donamy]

I would recommend using a transparent part, to view the startrackers. That way you eliminate distortions, on the nose section. Also, you can place them anywhere.

 

[DaveS]

I would recommend using a transparent part, to view the startrackers. That way you eliminate distortions, on the nose section. Also, you can place them anywhere.

Could you make a step-by-step on that? Also, does it give the depth like you see in the photos?

 

[Donamy]

It does when I use it for the thrusters, in my dragoncapsule.

You just have to place the fuselage part, after the transparent ones in the mesh.

 

[Capt_hensley]

It does when I use it for the thrusters, in my dragoncapsule.

You just have to place the fuselage part, after the transparent ones in the mesh.

I did this once on the CST-100 capsule as well, Dammed if I can remember how, at this point. But Don has the right idea, hope you get this worked out. Great progress so far, looking forward to flying it some time. I'm sure this is gonna look great as the previews are very nice.

 

[DaveS]

I did this once on the CST-100 capsule as well, Dammed if I can remember how, at this point. But Don has the right idea, hope you get this worked out. Great progress so far, looking forward to flying it some time. I'm sure this is gonna look great as the previews are very nice.

Yeah, a few basic pointers would be great to get me started.