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#220
by
Jim
on 18 Mar, 2007 21:42
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ANDY_WALLACEGROVE - 18/3/2007 3:58 AM
First, can I say what a great site! The depth of members knowledge and the availability of info is just astonishing, thanks and congratulations.
My question is, can anyone direct me to some in-depth technical detail about the operation of the GPC's? The kind of thing i'm interested in is how the units combine to operate during critical phases, and the kind of redundancy/resilience is employed to deliver fault-tolerance.
Andy
It can be found on L2.
I know I will be corrected if I am wrong.
But basically 4 GPC's combine to provide a redundant set with the GPC's voting the oddball out. The 5th is running backup software (BFS) which has different coding than what is used (PASS) in the others
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#221
by
mkirk
on 18 Mar, 2007 21:42
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Well a good to place to start would be at this link on the DPS system from an older version of the SCOM (Crew Operations Manual) that is publicly available;
http://www.shuttlepresskit.com/scom/26.pdfIf you have specific questions feel free to ask, someone out there will likely know the answer.
Mark Kirkman
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#222
by
Jim
on 18 Mar, 2007 21:56
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mkirk - 18/3/2007 6:42 AM
If you have specific questions feel free to ask, someone out there will likely know the answer.
Mark Kirkman
That would be you, Mark.
I forgot about the older version of the SCOM online. L2 has a newer version
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#223
by
joema
on 19 Mar, 2007 11:11
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#224
by
ANDY_WALLACEGROVE
on 19 Mar, 2007 17:25
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Thanks all. Am an L2 member, so will digest the info and comeback with any q's. Thanks again
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#225
by
shuttlepilot
on 28 Mar, 2007 18:31
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I have small question. Many times on many videos of shuttle launch aborts I heard call, probably from CGLS "GLS safing is in progress, BFS is 101, PAS is 101 and LBD is 1"... But what BFS, PAS and LBD mean? I know that for many people from here it's stupid question, but I'm newbie so I don't know many things
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#226
by
Jim
on 28 Mar, 2007 18:43
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shuttlepilot - 28/3/2007 2:31 PM
I have small question. Many times on many videos of shuttle launch aborts I heard call, probably from CGLS "GLS safing is in progress, BFS is 101, PAS is 101 and LBD is 1"... But what BFS, PAS and LBD mean? I know that for many people from here it's stupid question, but I'm newbie so I don't know many things
There is an acronym list somewhere on the site
BFS - Backup Flight Software
PASS - Primary Avionics Software System
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#227
by
mkirk
on 28 Mar, 2007 18:58
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shuttlepilot - 28/3/2007 1:31 PM
I have small question. Many times on many videos of shuttle launch aborts I heard call, probably from CGLS "GLS safing is in progress, BFS is 101, PAS is 101 and LBD is 1"... But what BFS, PAS and LBD mean? I know that for many people from here it's stupid question, but I'm newbie so I don't know many things
Jim go the first two as for the third I think you mean LDB not LBD which is Launch Data Bus.
LDB 1 refers to the data source in the Launch Control Center Firing Room.
Mark Kirkman
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#228
by
shuttlepilot
on 28 Mar, 2007 19:39
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Thanks for your answers.
Greetings.
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#229
by
Jorge
on 28 Mar, 2007 20:49
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Jim - 28/3/2007 1:43 PM
shuttlepilot - 28/3/2007 2:31 PM
I have small question. Many times on many videos of shuttle launch aborts I heard call, probably from CGLS "GLS safing is in progress, BFS is 101, PAS is 101 and LBD is 1"... But what BFS, PAS and LBD mean? I know that for many people from here it's stupid question, but I'm newbie so I don't know many things
There is an acronym list somewhere on the site
BFS - Backup Flight Software
PASS - Primary Avionics Software System
And just to tidy up, the "101" is the software major mode. The hundreds digit is the Operational Sequence or OPS. OPS 1 is ascent, OPS 2 is orbit, and OPS 3 is entry. (There are others for RTLS, on-orbit checkout, ground checkout, etc). Within OPS 1, major mode 101 is prelaunch, 102 is first stage (SRB+SSME) powered ascent, 103 is second stage, etc. So the call is simply to confirm that both PASS and BFS are in the correct major mode.
--
JRF
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#230
by
Gary
on 29 Mar, 2007 00:24
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I was just looking over the execute packages for recent missions and I just realised the amount of DETAIL in the replanned sections of the execute packages. It's really very in depth and I was wondering what software is used to create both the execute packages and the detailed time line plans.
Thanks.
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#231
by
mjp25
on 06 Apr, 2007 23:41
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How many complete SRBs or if it is easier, SRB segments, have been bult since the start of the STS program? What is done with a segment when it has outlived its usefulness? What is the greatest number of flights a segement has been used on? The least? (not counting STS-4 where the SEBs sank) Idle questions really. I could probably compile the info myself, but if someone has it handy I would be interested. Thanks.
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#232
by
shuttlefan
on 12 Apr, 2007 13:34
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Does anyone know where I could find a complete log of all Space Shuttle Main Engine test firings since the start of the program up to now? Also, when is the next one scheduled?
Thank-you!
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#233
by
Firehawk153
on 16 Apr, 2007 05:04
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I've noticed on some launches that the shuttle's OMS will fire after SRB seperation to aid the shuttle's ascent to orbit. Two questions about this:
1.) The OMS engines produce relatively little thrust compared to the monster SSME's (what, about 12,000 lbs. of thrust for both as opposed to 1.2 million lbs of thrust for the SSME.) Why do they even need them? That's like a leaf blower next to a Trent 900 jet engine.
2.) Why wouldn't they wait until after ET seperation to burn the engines instead of burning the engines while the ET (and its remaining propellants) are still attached to the orbiter?
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#234
by
Space101
on 16 Apr, 2007 05:09
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Firehawk153 - 15/4/2007 12:04 AM
I've noticed on some launches that the shuttle's OMS will fire after SRB seperation to aid the shuttle's ascent to orbit. Two questions about this:
1.) The OMS engines produce relatively little thrust compared to the monster SSME's (what, about 12,000 lbs. of thrust for both as opposed to 1.2 million lbs of thrust for the SSME.) Why do they even need them? That's like a leaf blower next to a Trent 900 jet engine.
2.) Why wouldn't they wait until after ET seperation to burn the engines instead of burning the engines while the ET (and its remaining propellants) are still attached to the orbiter?
Good one. Put me down for wanting to know too!
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#235
by
privateer
on 16 Apr, 2007 05:53
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Firehawk153 - 15/4/2007 12:04 AM
I've noticed on some launches that the shuttle's OMS will fire after SRB seperation to aid the shuttle's ascent to orbit. Two questions about this:
1.) The OMS engines produce relatively little thrust compared to the monster SSME's (what, about 12,000 lbs. of thrust for both as opposed to 1.2 million lbs of thrust for the SSME.) Why do they even need them? That's like a leaf blower next to a Trent 900 jet engine.
I think SSMEs are not used for the last push because SSMEs run on fuel supplied by ET -> if you use SSMEs for orbital insertion you end up *orbiting ET* too! Which is going to be quite a piece of space debris then...
2.) Why wouldn't they wait until after ET seperation to burn the engines instead of burning the engines while the ET (and its remaining propellants) are still attached to the orbiter?
I think OMW can be used a bit for attitude control while tank is still attached.
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#236
by
Jim
on 16 Apr, 2007 11:47
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Firehawk153 - 16/4/2007 1:04 AM
I've noticed on some launches that the shuttle's OMS will fire after SRB seperation to aid the shuttle's ascent to orbit. Two questions about this:
1.) The OMS engines produce relatively little thrust compared to the monster SSME's (what, about 12,000 lbs. of thrust for both as opposed to 1.2 million lbs of thrust for the SSME.) Why do they even need them? That's like a leaf blower next to a Trent 900 jet engine.
2.) Why wouldn't they wait until after ET seperation to burn the engines instead of burning the engines while the ET (and its remaining propellants) are still attached to the orbiter?
It is in Q&A part 2
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#237
by
Firehawk153
on 16 Apr, 2007 18:49
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I found the answer in part 2 of the Q&A; interesting...does the RCS/OMS propellant make up that significant of a portion of the orbiter's mass?
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#238
by
Jim
on 16 Apr, 2007 18:52
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Firehawk153 - 16/4/2007 2:49 PM
I found the answer in part 2 of the Q&A; interesting...does the RCS/OMS propellant make up that significant of a portion of the orbiter's mass?
Full load of OMS is 25k lb, which is near 10% of the orbiter weight
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#239
by
ANDY_WALLACEGROVE
on 19 Apr, 2007 12:16
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Can someone enlighten me as to whether the microwave landing system noted in the presskit of STS1 (see below) is used for guidance (radar) or control (autopilot). If the latter, is it ever used?
"Young and Crippen will land Columbia manually on this first test flight. A microwave landing system on the ground will be the primary landing aid in subsequent flights, with optional manual takeover"
