Centaur G/G Prime High Energy Upper Stage

[DaveS]

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.

I'm currently working on a updated G Prime which is more accurate, including the REM locations. I'll take a look at the thrusters once the new mesh is done.

Edit:
You might want to look over some Atlas V/Centaur launch videos that includes the STK views as the REMs on the Centaur hasn't changed since the very first AC launch in 1962.

 

[GLS]

I'm currently working on a updated G Prime which is more accurate, including the REM locations. I'll take a look at the thrusters once the new mesh is done.

OK, but when you're done please do the thruster list thing, so that we're all on the same page.

 

[DaveS]

One thing I noticed on the CISS is that the Deployment Adapter rotation links and arms isn't animated. These arms and links are connected to the actual PDUs that rotate the Deployment Adapter. The arms rotate CCW.

---------- Post added at 03:11 PM ---------- Previous post was at 02:16 PM ----------

Two screenshots of the updated G Prime. Primary changes include accurate design of the fwd Equipment Module avionics boxes (the ones currently missing are the two FIBs, the Power Amplifier(PA), the Remote Multiplexer Unit(RMU), the Signal Conditioner(SC), the Mixed Motor Inverters(MMIs), and the Inertial Reference Unit(IRU)) and the addition of the RL-10's.

Donamy: Once I'm done with the fwd Equipment Module, do you think you could add the wiring? To give you an idea of what the wiring looks like, here's a package of photos and images: https://dl.dropboxusercontent.com/u/24122088/STSCentaur/Centaur_Equipment_Module.zip

 

[DaveS]

Centaur RCS layout:

 

[DaveS]

In case someone was wondering where that graphic came from: Titan/Centaur T/C-1 post flight evaluation report

---------- Post added at 11:45 PM ---------- Previous post was at 09:39 PM ----------

Notes re Centaur RCS:

• RCS assemblies are located on the 45°, 135°, 225° and 315° vehicle axis
• The four aft directed engines (designated S2A, S2B, S4A and S4B) provide axial thrust for propellant setlling during coast periods, and for displacement of Centaur away from the payload after separation. Two vehicle thrust levels are obtainable for these functions by using one of both pairs of axial engines
• Each thruster consumes approximately 0.038 lb/s of propellant while firing in a continuous mode

 

[GLS]

Looking at the diagram it seems my original guess of the thruster order was correct, but I had the wrong nomenclature... I'll fix it.
But now I see another problem: the pitch and yaw axis are switched in the mesh vs the diagram (the Y axis in the diagram is up in the PLB, right?). If so, we could use "void SetCameraDefaultDirection (const VECTOR3 &cd, double tilt) const;" to rotate the view from the Centaur thus giving the impression to the user of pitch we he/she pitchs, but orbiter would still "process" a yaw. The alternative would be rotate the mesh around it's Z axis.

 

[DaveS]

I'll rotate the mesh. If you want you could rotate the current mesh using ShipEdit to give yourself a head start.

 

[Graham2001]

A trio of possibly useful documents from the NTRS

Zero-G thermodynamic vent system for shuttle/Centaur

Viewgraphs are presented showing drawings of Centaur configurations, the Thermodynamic Vent System (TVS), the mixer pump, and the hydrogen vent motor pump inverter. A cryogenic performance summary is given in chart form. The TVS liquid flow operation and vapor flow operation are diagrammed.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880006561.pdf


The 250AH/90A active lithium-thionyl chloride cell for Centaur-G application

A high rate active Li/SOCl2 cell was designed for use in a 28 volt, 250 amp-hour space battery system. The lithium battery is being considered as a replacement of its heavier silver-zinc counterpart on board the Centaur-G booster rocket which is used to launch payloads from the Space Shuttle cargo bay into deep-space.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880001641.pdf


Design, development and test of shuttle/Centaur G-prime cryogenic tankage thermal protection systems

The thermal protection systems for the shuttle/Centaur would have had to provide fail-safe thermal protection during prelaunch, launch ascent, and on-orbit operations as well as during potential abort. The thermal protection systems selected used a helium-purged polyimide foam beneath three rediation shields for the liquid-hydrogen tank and radiation shields only for the liquid-oxygen tank (three shields on the tank sidewall and four on the aft bulkhead).

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870014252.pdf

 

[DaveS]

Here's some interesting documents:
RL10 Engine Ability to Transition from Atlas to Shuttle/Centaur Program

Reflections on Centaur Upper Stage Integration by the NASA Lewis (Glenn) Research Center

Shuttle Centaur engine cooldown evaluation and effects of expanded inlets on start transient

RL10 ignition limits test for Shuttle Centaur

RL10A-3-3A Rocket Engine Modeling Project

A transient model of the RL10A-3-3A rocket engine

A high energy stage for the National Space Transportation System

 

[DaveS]

One thing I noticed on the CISS is that the Deployment Adapter rotation links and arms isn't animated. These arms and links are connected to the actual PDUs that rotate the Deployment Adapter. The arms rotate CCW.

Could this be added? I need to run some tests on that animation since I don't know quite how it works.

 

[Graham2001]

Two more documents, both of which might be useful for scenario creation.

Centaur operations at the space station (1987)

A study was conducted on the feasibility of using a Centaur vehicle as a testbed to demonstrate critical OTV technologies at the Space Station. Two Technology Demonstration Missions (TDMs) were identified: (1) Accommodations, and (2) Operations. The Accommodations TDM contained: (1) berthing, (2) checkout, maintenance and safing, and (3) payload integration missions. The Operations TDM contained: (1) a cryogenic propellant resupply mission, and (2) Centaur deployment activities. A modified Space Station Co-Orbiting Platform (COP) was selected as the optimum refueling and launch node due to safety and operational considerations. After completion of the TDMs, the fueled Centaur would carry out a mission to actually test deployment and help offset TDM costs. From the Station, the Centaur could carry a single payload in excess of 20,000 pounds to geosynchronous orbit or multiple payloads.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880016089.pdf


Centaur operations at the space station: Cost and transportation analysis (1988)

A study was conducted to expand on the results of an initial study entitled Centaur Operations at the Space Station. The previous study developed technology demonstration missions (TDMs) that utilized the Centaur G-prime upper stage to advance OTV technologies required for accomodations and operations at the Space Station. An initial evaluation was performed of the cost to NASA for TDM implementation. Due to the potential for commercial communication satellite operation utilizing the TDM hardware, an evaluation of the Centaur's transportation potential was also performed.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880020451.pdf

 

[DaveS]

Nearly done with the new Centaur G Prime. It has been pretty much redone from scratch to fit the new orbiter. Once the upper stage itself is done, I have to apply the same treatment to the CISS.

 

[DaveS]

The G Prime is nearly done. The only thing it is lacking right now is a few more avionics boxes on the Equipment Module, the cover for the LH2 engine feedline and the twin R10A3-A3's. So to quote former United Space Alliance Orbiter Test Conductor Mark Craxton: "It's been a long road with many detours but your patience is about to be rewarded. It's time to fly." STS-115 pre-launch, September 9 2006.

 

[GLS]

How hard would it be to modify the G Prime (and CISS) meshes to create the G version? If it's not much work and it would only be a couple more days, I wouldn't mind the delay to have both versions in this release. If it's more then it probably is a good idea to leave the G for another release.

 

[DaveS]

How hard would it be to modify the G Prime (and CISS) meshes to create the G version? If it's not much work and it would only be a couple more days, I wouldn't mind the delay to have both versions in this release. If it's more then it probably is a good idea to leave the G for another release.

It wouldn't be hard at all. I estimate about a day or so. I recently found out that NASA had in fact bought a G for the Magellan Venus Radar Mapping Mission (VRM). I believe the launch was planned for October 1989.

 

[GLS]

It wouldn't be hard at all. I estimate about a day or so. I recently found out that NASA had in fact bought a G for the Magellan Venus Radar Mapping Mission (VRM). I believe the launch was planned for October 1989.

Yeah, and I've read that it would launch the TDRS birds as well. Anyway, somebody will find something to launch in it. :lol:

 

[DaveS]

What exactly is planned in terms of features for the first release? At the very minimum we need the ability to specify custom spacecraft adapters.

 

[GLS]

What exactly is planned in terms of features for the first release? At the very minimum we need the ability to specify custom spacecraft adapters.

To me, a simplex version would work: RCS & RL10s. We don't have aborts in the shuttle yet so there's no point in thinking about a more advanced plumbing. For the deployment, I'm willing to use F3 and change to the CISS for now, because it would take a lot of time to have the panel and the S/W working, and I think there's more important stuff on our "to-do list".
About the spacecraft adapters, that would stay with the Centaur after spacecraft separation, right? If so, then we would need an option in the scenario file (something like "ADAPTER 1", "ADAPTER 2", etc), so we could adjust the attachment point and show the appropriate mesh group/part/whatever. Or, we could leave that mesh to the user, and they just say in the scenario "ADAPTER_MESH adaptermesh.msh" and "ADAPTER_OFFSET 2.74", so we can show the user's mesh and adjust the attachment point.
I vote for the last one, but we need some documentation with diagrams and stuff.

 

[DaveS]

About the spacecraft adapters, that would stay with the Centaur after spacecraft separation, right? If so, then we would need an option in the scenario file (something like "ADAPTER 1", "ADAPTER 2", etc), so we could adjust the attachment point and show the appropriate mesh group/part/whatever. Or, we could leave that mesh to the user, and they just say in the scenario "ADAPTER_MESH adaptermesh.msh" and "ADAPTER_OFFSET 2.74", so we can show the user's mesh and adjust the attachment point.
I vote for the last one, but we need some documentation with diagrams and stuff.

I too think the last option is the better one.

I'm posting this document here since it is related to the Centaur G Prime: Galileo: Exploration of Jupiter's system (1985)

 

[hutchison66]

Hi there, I love the work you guys do its really beyond me and my machine but do love it,
what I'd like to ask is I have managed to get the old Centaur prime from your last release SSU 2 to work with the shuttle fleet and would like to release it to the community, I would make it clear that the work is yours and would not pass it off as my own.
I of course couldn't get the pipes in the CISS to flex but I have it there is a separation valve in there when it rotates maybe it might help you in your work to see it.
thanks for all your work and would be pleased to get your response
David