-
#220 by Mark Dave on 21 Jul, 2006 20:32
-
I was wondering on launch day you hear "GLS is go...". Is there an operator for the GLS? I ask because usually I heard the GLS is automatic computer only. *shrugs*
What about the SRBs? How's the status of those going? -
#221 by mkirk on 21 Jul, 2006 20:43
-
Quote
MarkD - 21/7/2006 3:19 PM
I was wondering on launch day you hear "GLS is go...". Is there an operator for the GLS? I ask because usually I heard the GLS is automatic computer only. *shrugs*
What about the SRBs? How's the status of those going?
Yes there is a console operator position for the GLS (called CGLS), he/she ensures the GLS software is configured properly and executing the required tasks. This is a very critical postion for PAD Aborts.
The GLS console will annuciate a Go/No Go indication at the various countdown milestones and that is what you are normally hearing. Ex: "GLS is go for ET LO2 Pressurization."
Mark Kirkman -
#222 by dds121 on 24 Jul, 2006 04:50
-
These two threads have been quite fun to read, and now I have a question. Supposing there were to be a TAL, for instance, how would the orbiter get back to KSC? Can the Shuttle Carrier Aircraft carry it over an ocean?
-
#223 by norm103 on 24 Jul, 2006 05:52
-
yes the SCA will bring it back but would take a norther flight path over land. keep in mind the SCA is a fuel eat're.
-
#224 by shuttlefan on 27 Jul, 2006 13:40
-
When the shuttle is hoisted down to the ET and SRBs in the VAB, are any of the crews' seats intalled yet? SEEMS TO ME I've read about some or all of the seats only being installed later...I could be wrong.
-
#225 by Jim on 27 Jul, 2006 13:51
-
The middeck has no lockers and seats, and the flight deck only has the CDR and PLT seats installed (they are permanent).
The whole crew cabin is "gutted" after each mission (most of it at landing and remainder in the OPF in the following days). This allows access to the avionics bay and other systems. "Flight Crew Equipment" is handled by specific organizations at JSC and KSC. Most of the items are prepacked at JSC and shipped to KSC for installation. The cabin is temp setup for TCDT and then removed. The final setup is in the last week before launch. -
#226 by shuttlefan on 27 Jul, 2006 14:02
-
Thank-you, Jim!!
-
#227 by Austin on 27 Jul, 2006 23:13
-
I have a question about the shuttle's computers. I know that there are a total of 5 onboard computers -- four primary and the other redunant which moniters the health of the other four. But I've always wondered why NASA has continued with the same computers which, if I am correct, are essentially 70's technology. Does the adage "If it ain't broke don't fix it" apply here?
-
#228 by Chris Bergin on 27 Jul, 2006 23:17
-
Quote
Austin - 28/7/2006 12:00 AM
I have a question about the shuttle's computers. I know that there are a total of 5 onboard computers -- four primary and the other redunant which moniters the health of the other four. But I've always wondered why NASA has continued with the same computers which, if I am correct, are essentially 70's technology. Does the adage "If it ain't broke don't fix it" apply here?
I'd say you've got it right. The "they are old" gets overplayed a lot, because they do the job. Ironically, on the last two flights, what computers have they had problems with? The fancy new Window's driven laptops!
-
#229 by Austin on 27 Jul, 2006 23:25
-
Quote
Chris Bergin - 27/7/2006 4:04 PM
QuoteAustin - 28/7/2006 12:00 AM
I have a question about the shuttle's computers. I know that there are a total of 5 onboard computers -- four primary and the other redunant which moniters the health of the other four. But I've always wondered why NASA has continued with the same computers which, if I am correct, are essentially 70's technology. Does the adage "If it ain't broke don't fix it" apply here?
I'd say you've got it right. The "they are old" gets overplayed a lot, because they do the job. Ironically, on the last two flights, what computers have they had problems with? The fancy new Window's driven laptops!
Gotcha. Muchas gracias, Chris! -
#230 by Rocket Guy on 28 Jul, 2006 01:33
-
Old they say? There are countless commercial jetliners from the 1960s and 70s still flying today. As long as they pass their tests, they keep them going. And I'm quite sure the orbiters are tested more ;-)
Think about this (as I shared on another forum yesterday)...It was 50 years ago Tuesday night that the Stockholm collided with the Andrea Doria. The heavily-damaged-in-1956 Stockholm is still sailing cruises out of Europe under a different name. It set sail on a cruise to Morocco just two weeks ago! -
#231 by Jim on 28 Jul, 2006 02:18
-
Quote
Austin - 27/7/2006 7:00 PM
I have a question about the shuttle's computers. I know that there are a total of 5 onboard computers -- four primary and the other redunant which moniters the health of the other four. But I've always wondered why NASA has continued with the same computers which, if I am correct, are essentially 70's technology. Does the adage "If it ain't broke don't fix it" apply here?
They were replaced with B-1 bomber computers in the late 80's. Same architecture, but it combined two boxes into one. This allowed easier logistics since the B-1 computer would be supported for a longer timeframe.
Changing the computers would have a big impact on the shuttle program.
1. finding a computer that fits into the existing avionics architecture
2. rewriting all the code in a newer language
3 rewriting the backup software into a newer but different code
4. Validating the system
5. Updating the systems at KSC and JSC that interface with the orbiters and the GPC (software and maybe hardware mods) and validationing the upgrades
6. cutting in the new system into the orbiter, simulators, etc
Number 6 is the real problem. How do you do that and still support flying missions. Both types of computers would have to be supported. There would need to be two of everything, except there is only 1 fixed base and 1 motion base simulators, one SAIL, two KSC firing rooms would have to be different along with 2 JSC MOCR's
Actually, the 4 computers watch themselves and if two get voted out ( 2 separate failures) and the two have a disagreement, the 5th takes over with a different software. -
#232 by Austin on 28 Jul, 2006 02:55
-
Quote
Jim - 27/7/2006 7:05 PM
They were replaced with B-1 bomber computers in the late 80's. Same architecture, but it combined two boxes into one. This allowed easier logistics since the B-1 computer would be supported for a longer timeframe.
I never knew that they were replaced with B-1 bomber computers -- fascinating.QuoteChanging the computers would have a big impact on the shuttle program.
6. cutting in the new system into the orbiter, simulators, etc
Number 6 is the real problem. How do you do that and still support flying missions. Both types of computers would have to be supported. There would need to be two of everything, except there is only 1 fixed base and 1 motion base simulators, one SAIL, two KSC firing rooms would have to be different along with 2 JSC MOCR's
What about installing new computers in phases say, during the orbiters' OMPD (Orbiter Major Modification period) rather than all at once? -
#233 by astrobrian on 28 Jul, 2006 02:58
-
You would still have to support both types of code and hardware regardless as you cant just ground the fleet and upgrade them all at once. So you'd still be encountering the two of everything
Using code A and code B as examples. Atlantis would be on code A and Discovery on code B after refit. You would have to either have a MCC that supported both codes A and B, or you would have to have two MCC each set up for one or the other. Hopefully that helps
-
#234 by Austin on 28 Jul, 2006 03:54
-
Jim/Brian -- thanks, sure does.
-
#235 by elmarko on 29 Jul, 2006 11:54
-
Quote
Chris Bergin - 28/7/2006 12:04 AM
Ironically, on the last two flights, what computers have they had problems with? The fancy new Window's driven laptops!
While I appreciate this is probably meant as a joke, I think you can agree that the two configurations are totally different, and you absolutely cannot make a comparison in reliability between something designed for one purpose, and a multi-purpose setup like a standard home PC
Still funny though! -
#236 by j2_ on 31 Jul, 2006 17:58
-
Awesome info in this thread. I'm pleasently surprised that there are so many people interested in this much STS detail, and I'm absorbing it all.
Now, I do have a couple of questions about the Attitude Timeline, and flying the shuttle.
I've been playing with the truly amazing (and free!) Orbiter spaceflight simulator on and off for the past year or so. I'm hardly an expert, but I can launch a shuttle, rendezvous and dock with the ISS. I haven't tried a manual re-entry yet, but watching the autopilot fly the reentry is fascinating.
Anyways, here are the questions:
1) Why are the OMS rockets not aligned with the X axis of the orbiter? I believe they are tilted up (+Z i believe) about 15 degrees? I learned in Orbiter that most burns are done prograde. Does this mean the orbiter has to orient itself slightly pitched up with respect to the velocity vector when doing OMS burns?
2) Why does NASA launch the shuttle so far away from the ISS in orbit? It takes two days for the orbiter to catch the ISS from a lower altitude orbit. I know that in the Orbiter sim, if I time my launch correctly, I can rendezvous with the station within about 2.5 hours after launch.
And finally, my real question:
3) I want to fly the shuttle missions as realistically as possible in Orbiter. I've been trying to figure out how to perform all the OMS burns such as NC1, NCC, TI, etc. by looking at the Attitude Timeline from STS-121. I'm having trouble interpreting the attitude I should place my simulated shuttle in for the various OMS burns indicated in the timeline. I see that the delta V is indicated in the timeline as well, but how do I know how to burn my OMS engines for? Can I use my velocity readout on the Orbit MFD to time my OMS burns? (Of course converting from meters/sec to feet/sec) Or is there another instrument I should be looking at?
I can't wait to run my own simulation of the upcoming STS-115 mission, and I want to make sure I do all the OMS burns as realistically as possible!
Thanks -
#237 by Jim on 31 Jul, 2006 18:46
-
1. The OMS are aligned with the thrust vector going through the CG of the orbiter. If they were aligned with the x-axis, the orbiter would pitch down everytime the OMS burn
2. OMS fuel and they don't want to approach the ISS at a rate where a lot of thrusting is required, to minimize plume impengment. Also they need to check out the orbiter and put it into the on orbit configuration.
3. The timeline burn numbers are for reference. The actuals are provide by MCC before each burn, including TIG and duration of burn. the delta V is not cumulative and not related to orbital speed. -
#238 by DaveS on 31 Jul, 2006 20:07
-
This isn't a question on the orbiters. But does anyone have any good close-ups on the T-0 umbilical panels on the MLPs?
-
#239 by elmarko on 01 Aug, 2006 12:38
-
Quote
Jim - 31/7/2006 7:33 PM
1. The OMS are aligned with the thrust vector going through the CG of the orbiter. If they were aligned with the x-axis, the orbiter would pitch down everytime the OMS burn
In Orbiter the craft pitches down when you fire the OMS engines, because of the 13 degree offset. Is this the wrong behaviour? Should the offset mean that the pitch down is cancelled out?
