SSU Development thread (4.0 to 5.0) [DEVELOPMENT HALTED DUE TIME REQUIREMENTS!]

[DaveS]

I don't know but this seems to be too high. Especially that Shuttle doesn't normally use WSB for hydraulics during ascent.

WSBs are used during the entire time the APUs are running. I think you're confusing the WSB with FES which are used for overall vehicle cooling during ascent/descent. Below 100k NH3 boilers are used. To extend the lifetime of the NH3 boilers during descent, the vehicle is coldsoaked for the entire day prior to the planned landing day so that as much cold Freon-21 is trapped in the radiators when they're bypassed prior to PLBD Closure. That's why the CDR is only instructed to turn on the NH3 boilers once the coldsoaked Freon has been depleted (which usually is well after wheelstop on the runway).


The NH3 boilers are then used until the ground cooling cart (callsign "Cool 2") has been hooked up to the vehicle and is ready to flow.

 

[Gingin]

I think you are partially right Abdullah

WSB are always on like mentionned Dave.
However, during ascent, Oil doesn't heat enough to require the spray mode ( stagnant water in the boiler is enough up to 10 mn into the mission

And



The hydraulic fluid usually does not heat up enough during ascent to require water spray cooling


So WSB on, but water quantities don't vary normally during ascent or very lately due to the spray mode activated by hot Lubricating oil

 

[Abdullah Radwan]

Based on this information, what's the deal with 21 F per second? That'll require water spraying even before liftoff, as the water spray is active when the temperature is 210 F. I am sure there is something wrong with my calculation. Can somebody help?

Back to the hold at T-9.5 seconds: After monitoring the SSME phase and mode, I noticed before the hold it's in phase 1 mode 6. What does this mean? It should be in phase 2 mode 5.

 

[GLS]

Back to the hold at T-9.5 seconds: After monitoring the SSME phase and mode, I noticed before the hold it's in phase 1 mode 6. What does this mean? It should be in phase 2 mode 5.

It means you probably have been changing code that you shouldn't, as that is sensor checkout mode, which currently there is no way to command (no LCC consoles to do that).
Anyway, the log should have info on the cause of the abort.

 

[Abdullah Radwan]

This is the log:

000101.878: LCC: LPS Go For Main Engine Start
000101.878: LCC: Fire SSME H2 Burn PICs
000102.420: LCC: RS Countdown Hold Flag is on
000102.420: LCC: RS Seq SSME Go For Launch Hold
000102.420: LCC: Cutoff

 

[GLS]

This is the log:

000101.878: LCC: LPS Go For Main Engine Start
000101.878: LCC: Fire SSME H2 Burn PICs
000102.420: LCC: RS Countdown Hold Flag is on
[COLOR="Red"]000102.420: LCC: RS Seq SSME Go For Launch Hold[/COLOR]
000102.420: LCC: Cutoff

At least one SSME isn't in Engine Ready mode. The problem almost certainly happens before T-9.5s.

 

[Abdullah Radwan]

At least one SSME isn't in Engine Ready mode. The problem almost certainly happens before T-9.5s.

The engines aren't ready because it's in phase 1 mode 6. It must be in phase 2 mode 5. Why they are in phase 1 mode 6? What phase 1 mode 6 means?

I've never touched SSME code. The hydraulic pressure is above 3000.

 

[GLS]

The engines aren't ready because it's in phase 1 mode 6. It must be in phase 2 mode 5. Why they are in phase 1 mode 6? What phase 1 mode 6 means?

I've never touched SSME code. The hydraulic pressure is above 3000.

My memory could be at fault but AFAIR, although the phases and modes are in the SSME controller (some do nothing yet), only the flight-related commands, starting at PSN4, are commanded, so the test phases/modes should not run at all.

You might have found a bug somewhere, or you are causing things to happen that shouldn't happen. This is the reason I told you to isolate your work. :shrug:
Start with one system with one actuator and work the inner workings of them, without concerning with other systems. That's already plenty of work. Then add more actuators, with several command paths or whatever is needed. Towards the end, start having "real users", i.e., subsystems that actually implement the actuators and do things with them.
Each of these steps is hard enough and will have lots of problems by themselves, let alone trying to make all at once.

 

[Abdullah Radwan]

I've fixed it. The problem is that I moved the APU_HydraulicPress bundle to the hydraulic system without changing it in SSME.cpp. I've changed it there and it works now!

 

[GLS]

I've fixed it. The problem is that I moved the APU_HydraulicPress bundle to the hydraulic system without changing it in SSME.cpp. I've changed it there and it works now!

Correction: you temporarily fixed it. The SSME doesn't see the hydraulic pressure "via wire", but with its own sensor.

 

[Abdullah Radwan]

Correction: you temporarily fixed it. The SSME doesn't see the hydraulic pressure "via wire", but with its own sensor.

Where is the sensor? I don't think there are another ways to know the pressure, as I modified every function to the new system, including Atlantis and CRT displays.

 

[GLS]

Where is the sensor? I don't think there are another ways to know the pressure, as I modified every function to the new system, including Atlantis and CRT displays.

It isn't done yet, as there isn't an hydraulic system for it to measure. :shrug:
As I expected, you are putting the carriage in front of the horses, and then you will have to flip them around again. :facepalm:

I'll repeat myself (again): create the hyd system and an actuator and get the basics working well. Put a debug string output somewhere and use it for you to see what is going on. When it is all working, then the integration with the existing subsystems can take place. That's when changing the subsystems to properly interface with the hydraulic system is needed, not before.

 

[Abdullah Radwan]

It isn't done yet, as there isn't an hydraulic system for it to measure. :shrug:
As I expected, you are putting the carriage in front of the horses, and then you will have to flip them around again. :facepalm:

I'll repeat myself (again): create the hyd system and an actuator and get the basics working well. Put a debug string output somewhere and use it for you to see what is going on. When it is all working, then the integration with the existing subsystems can take place. That's when changing the subsystems to properly interface with the hydraulic system is needed, not before.

Thank you so much for your advice. I didn't understand it except now.
You mean that I should make the hydraulic system and actuator away from the original one, and integrate it after confirming it's working without problems. What I did is integrating it directly without any tests which caused these problems.


I'll follow this strategy in new implementations. It's too late to do this now, as I've removed the original code.

 

[GLS]

https://web.archive.org/web/2010051...casi.ntrs.nasa.gov/19850070642_1985070642.pdf

Most of old NTRS was saved this way. You have no idea how many Apollo documents we could (and had to) recover this way... Just doesn't work for any documents added to NTRS after 2011.

Anyone has Part 2 of this?

 

[indy91]

One thing that has recently helped us find documents was this list of restricted NTRS documents: https://forum.nasaspaceflight.com/index.php?topic=45825.0

A lot of these were previously available, others not. We actually managed to get two LM Data Book documents back on the public NTRS by requesting it with the NTRS ID! Just took many months and we never even got a notification that it was now available, haha.

Anyway, the list has an appendix to Volume I of that document, but unfortunately it is not available in the archived NTRS. Maybe it was never publically available.

19850070641 Preoperational aerodynamic design data book. Volume 1. Orbiter vehicle: Appendices 1978

The only other thing I found that was available was:

Aerodynamic design data book. Volume 1M: Orbiter vehicle STS-1 from 1980

 

[GLS]

One thing that has recently helped us find documents was this list of restricted NTRS documents: https://forum.nasaspaceflight.com/index.php?topic=45825.0

A lot of these were previously available, others not. We actually managed to get two LM Data Book documents back on the public NTRS by requesting it with the NTRS ID! Just took many months and we never even got a notification that it was now available, haha.

Anyway, the list has an appendix to Volume I of that document, but unfortunately it is not available in the archived NTRS. Maybe it was never publically available.



The only other thing I found that was available was:

Aerodynamic design data book. Volume 1M: Orbiter vehicle STS-1 from 1980

I got as far as that list, and I already had that document. Thanks anyway.
The lateral aero data we currently have is different from the data in the STS-1 document, and is missing on the other more recent (1982) document... Anyway, I'll use the data in the STS-1 document, as it was good enough to bring Young and Crippen home. :shrug:

 

[Wolf]

Any idea on when the SSU mesh will be done? Weeks, months..?
I am stuck with the textures til the mesh will be fixed..

 

[DaveS]

Any idea on when the SSU mesh will be done? Weeks, months..?
I am stuck with the textures til the mesh will be fixed..

It will still be a while but I can say that the texture mapping will remain as it is now (revision 2904). Nothing has been changed there at all.

 

[Wolf]

It will still be a while but I can say that the texture mapping will remain as it is now (revision 2904). Nothing has been changed there at all.

Ok. I will wait until all related tickets have been cleared and we are positive that the mesh will NOT require any further tweaking. Then I ll start working on the textures

 

[DaveS]

Nearly there with all the mesh work on the orbiter. Latest addition is the EVA slidewires that are mounted to the PLBDs. These will require child animations of the PLBD animations as they're also attached to the PLB sills by links and the brackets rotate as the doors move. The details can be found in JSC-1117 Vol. II, page 224-225.
https://www.dropbox.com/s/l3mu32cy5laoht3/Updated_SSU_Orbiter_1.jpg?dl=0
https://www.dropbox.com/s/4unxdg8q9jwabcd/Updated_SSU_Orbiter_2.jpg?dl=0