Centaur G/G Prime High Energy Upper Stage

[DaveS]

I don't think it's a major problem having to change vessels (we have bigger "holes" in SSU at the moment). The lack of dump capability is not really a problem as we still don't have aborts.
Although I really want to have the Centaur working, it has to wait until after the configuration program/editor/whatever is done. Once we have that square away, I'm planning on creating a branch for centaur (and another for OMS/RCS), and get that train moving.

The problem is worse than just switching vessels/dumping the propellants in the event of an abort: SC3 doesn't support attachments with user-definable velocities. Sep velocity is a very hard-coded 0.000000000 m/s. So Centaur/CISS sep is currently NO-GO.

 

[GLS]

The problem is worse than just switching vessels/dumping the propellants in the event of an abort: SC3 doesn't support attachments with user-definable velocities. Sep velocity is a very hard-coded 0.000000000 m/s. So Centaur/CISS sep is currently NO-GO.

That could be a problem...
I could create a temporary Centaur branch now to code some simple SC and CISS vessels (no fancy stuff yet) so we get this to a "releasable" state, and then in a few months time we can add all the goodies. Sounds good?

 

[DaveS]

That could be a problem...

I could create a temporary Centaur branch now to code some simple SC and CISS vessels (no fancy stuff yet) so we get this to a "releasable" state, and then in a few months time we can add all the goodies. Sounds good?

Yes, that sounds good. It could allow us to start on a common framework for shuttle upper stages as all of them made use of an ASE in some form.

 

[GLS]

Yes, that sounds good. It could allow us to start on a common framework for shuttle upper stages as all of them made use of an ASE in some form.

I'm thinking about doing just the vessels, no remote stuff, no dumps, no panels, no displays. Just something to add mass, deploy the centaur and fire the engines.

 

[SiameseCat]

That could be a problem...
I could create a temporary Centaur branch now to code some simple SC and CISS vessels (no fancy stuff yet) so we get this to a "releasable" state, and then in a few months time we can add all the goodies. Sounds good?

Sounds good to me too.

 

[DaveS]

One basic item I'd like to see implemented is definition of a custom PAF. Considering that it would be just a static mesh, I think we could adapt the static cargo mesh code already in the orbiter.

 

[GLS]

OK, I think it's pretty much done except for 2 things: CISS animations and ACS. The first one is just too much for my little head :lol:. On the ACS, I just finished a 6 thruster system, that I now know is from the first centaurs because I just found 12 nozzles in the mesh :facepalm:. So if anyone could give me the x,y,z for position and direction of each of those thrusters, that would help a lot. (also noticed that 4 of them are pointing to were the RL10s would be... is that correct?)

 

[DaveS]

OK, I think it's pretty much done except for 2 things: CISS animations and ACS. The first one is just too much for my little head :lol:. On the ACS, I just finished a 6 thruster system, that I now know is from the first centaurs because I just found 12 nozzles in the mesh :facepalm:. So if anyone could give me the x,y,z for position and direction of each of those thrusters, that would help a lot. (also noticed that 4 of them are pointing to were the RL10s would be... is that correct?)

Positions and directions of REMs:

Pos
Dir

Naming convention is clockwise when looking forward from aft

REM1:
-1.06112 0.751872 -2.92064
-0.840362 -0.0981861 -0.533059

REM2:
-0.920389 0.894691 -2.91137
0.144188 0.882767 -0.447137

REM3:
0.993467 0.931987 -2.9481
-0.00410334 0.840309 -0.542092

REM4:
1.01708 0.784585 -2.9354
0.280308 0.485194 0.828259

REM5:
1.06405 0.735958 -2.92282
0.280308 0.485194 0.828259

REM6:
1.17345 0.707999 -2.89724
0.947194 -0.144266 -0.286375

REMs 7,8, mirror of REMs 1,2
REMs 9,10,11,12 mirror of REMs 3,4,5,6

And yes, there's two sets of forward firing REMs for pre-MES propellant settling.

 

[GLS]

I just commited the "upgrade". Current issues:
> thrusters don't match mesh (did the best I could)
> CISS animations are missing
> attachments direction and separation velocity direction need work
> small tweaks in CISS position in PLB needed (looks too low)
> (might need to update scenarios for animations)
Other than that, we just need the Ulysses and Galileo and I'd say it's good to go on this end.

 

[DaveS]

> thrusters don't match mesh (did the best I could): What is the issue? The positions and directions are directly from the mesh.
> CISS animations are missing: Problems with the animation data in the SC3 version?
> attachments direction and separation velocity direction need work: 45° deploy angle on the DA at 1 fps.

 

[GLS]

The coordinates you gave me don't match the mesh (different version?), and I think the signs on some directions were reversed. Currently the thrusters look to be firing in the right direction (and it's very controllable), but the source isn't exactly on the nozzles.
For the animations I don't know where all the numbers go and what functions to use (and I don't have the time to learn in the next 2 weeks or so).
And I'm not sure the attachments are 100% correct because the separation pushes the centaur (or satellite) in the wrong axis.

 

[DaveS]

Well, the G version is of a different, older version. Only the G Prime is near completion. And I see what you mean re the CISS. That I guess has to be done by someone who understands the coding of such an item.

 

[GLS]

I wrote the code +/- thinking about both versions, but I only found the G-Prime meshes... One thing I forgot to do is a check of the versions of both the Centaur and CISS, to make sure they always match, but it's not critical and eventually I'll get to it.
Another thing I forgot to ask is to have someone check the mass numbers in the header files to make sure they are in the ball park.

 

[DaveS]

Another thing I forgot to ask is to have someone check the mass numbers in the header files to make sure they are in the ball park.

I went through them and found some discrepancies and fixed them. The corrected files and have been checked in. One mission dependent mass is the Spacecraft System Mass, this is charged to the actual spacecraft payload, not the Centaur so this requires it's own implementation.

---------- Post added at 07:14 PM ---------- Previous post was at 05:33 PM ----------

I decided to post this request in this thread due to two main payloads for the Centaur G Prime making use of it:

Have anyone come across any photos or schematics of the RTG Cooling Kit that was flown on STS-34/41? It was used to cool the RTGs on Galileo and Ulysses while they were in the payload bay.

This is the description of the RTG Cooling Kit from the STS-34 presskit:

About 34 modifications have been implemented since the STS-30
mission. One significant modification is a cooling system for the
radioisotope thermoelectric generators (RTG). The RTG fuel is plutonium
dioxide which generates heat as a result of its normal decay. The heat is
converted to energy and used to provide electrical power for the Galileo
spacecraft. A mixture of alcohol and water flows in the special cooling
system to lower the RTG case temperature and maintain a desired
temperature to the payload instrumentation in the vicinity of the RTGs.
These cooling lines are mounted on the port side of the orbiter from the
aft compartment to a control panel in bay 4.

 

[DaveS]

With all the focus on the G Prime that actually did fly in a modified form on the Titan IV series, here's a few images of the shorter G that never got to the hardware stage:

 

[N_Molson]

You might like that one, too, obviously the same artist than pic. #2 above :

The probe is Galileo, they planned to deploy it that way before Challenger.

 

[Graham2001]

I've located an interesting looking document amongst the latest NTRS release. Could be useful for scenario design if nothing else.

Three Orbital Burns to Molniya Orbit via Shuttle Centaur G Upper Stage

An unclassified analytical trajectory design, performance, and mission study was done for the 1982-86 joint NASA-USAF Shuttle/Centaur G upper stage development program to send performance-demanding payloads to high orbits such as Molniya using an unconventional orbit transfer. This optimized three orbital burn transfer to Molniya orbit was compared to the then-baselined two burn transfer.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140016768.pdf

 

[ISProgram]

Don't forget Ulysses...

 

[DaveS]

Yes, that was STS-61F which was Challenger's next mission after STS-51L which is one of the reasons why KSC wanted to launch it ASAP so that Challenger could readied for the narrow launch window in May 1986.

 

[GLS]

Just committed an update to the attachments, so that now the Centaur doesn't fly thru the orbiter on deployment. The payload attachment might not be 100% correct... looks like the attachment for the Carina is "sideways", so I'm not sure it's perfect.
The RCS are still not good... some positions are way off and currently the rotation directions are reversed. DaveS could you take another look at the positions/directions of the thrusters? And then give me a location of each thruster, maybe draw a little sketch on paint or something, so then I can set the groups correctly to maneuver the thing. Something like "seen from the -Z direction with +Y on top, thrusters 1 and 2 are at the 11 o'clock position, etc" would be enough.