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#1100
by
elmarko
on 28 Apr, 2010 11:36
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Haha, thats nuts, but I understand the reasoning.
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#1101
by
Thorny
on 28 Apr, 2010 13:17
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Haha, thats nuts, but I understand the reasoning.
This all goes back to 2006, when Atlantis was going to be retired in 2008 rather than go through another every-seventh-flight Orbiter Major Modification inspection period (after which there would only be a year or so left in the Shuttle program.) So NASA didn't install SSPTS in Atlantis. But then NASA determined Atlantis could make another couple of flights without an OMM, so Atlantis ended up being the odd bird out.
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#1102
by
elmarko
on 28 Apr, 2010 15:08
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I think I was a little confused re the Atlantis question.
Was the original question how long can Atlantis stay at the station compared to other SSPTS-capable orbiters? I sort of already knew that it couldn't stay as long as the others, but I wondered how much.
Essentially I think the question is, if you take each orbiter (all 5), do they have similar periods of mission duration possible, and the answer, clearly, is no.
Apart from the SSPTS, and the Extended Duration Orbiter, are there any other things that affect it? As I mentioned, over the years orbiter design was refined, so perhaps did that play any part in extending possible duration?
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#1103
by
iskyfly
on 28 Apr, 2010 15:26
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On some of the ascent launch videos around t -10 seconds i hear something that I think is "Nav init".
What does that mean and what is being performed / checked?
Also, right after liftoff both CDR and PLT say "auto" and "small numbers".
What are they referring to?
Thanks!
-Giles
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#1104
by
DaveS
on 28 Apr, 2010 15:40
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1: Nav Int is short for navigation internal, that the nav systems are online.
2: It's "102, auto, auto". 102 refers to the software that he onboard GPCs are using. It's a verbal check that the GPCs have moded over from the prelaunch software to the stage 1 software, 102. There's a similar callout post-SRB sep, which is 103.
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#1105
by
Jim
on 28 Apr, 2010 17:22
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Apart from the SSPTS, and the Extended Duration Orbiter, are there any other things that affect it? As I mentioned, over the years orbiter design was refined, so perhaps did that play any part in extending possible duration?
No, the limiting factor was cryogens (O2 and H2) onboard. Most orbiters could carry 4 tank sets but 102 and 105 could carry 5. So 102 could stay on orbit longer than newer vehicles.
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#1106
by
elmarko
on 28 Apr, 2010 19:47
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Which is sort of what I said then? I guess.
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#1107
by
Jim
on 28 Apr, 2010 20:12
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Which is sort of what I said then? I guess.
The refined design did not have a part in extending the orbiter's duration. I don't include EDO and SSPTS as part of the orbiter design, they are kits.
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#1108
by
alexw
on 28 Apr, 2010 23:25
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No, the limiting factor was cryogens (O2 and H2) onboard. Most orbiters could carry 4 tank sets but 102 and 105 could carry 5. So 102 could stay on orbit longer than newer vehicles.
Why 102 and 105 -- did the fittings for the tank sets cost enough dry mass, or obstruct part of the payload bay, to make it worthwhile to spread around the capability? In practice, did the orbiters fly with less than their max # of tank sets? And, were the four sets in the EDO pallet the same in capacity to the standard four sets in each orbiter (ie, Atlantis could have doubled her duration had she ever flown with it, 102 and 105 a bit less)?
Thanks, -Alex
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#1109
by
10W29
on 28 Apr, 2010 23:40
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Apart from the SSPTS, and the Extended Duration Orbiter, are there any other things that affect it? As I mentioned, over the years orbiter design was refined, so perhaps did that play any part in extending possible duration?
No, the limiting factor was cryogens (O2 and H2) onboard. Most orbiters could carry 4 tank sets but 102 and 105 could carry 5. So 102 could stay on orbit longer than newer vehicles.
Actually the baseline is 5 tank sets for all the vehicles.
OV-103 will remove her 5th tank set for STS-133 for weight savings.
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#1110
by
Jim
on 29 Apr, 2010 00:50
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Actually the baseline is 5 tank sets for all the vehicles.
OV-103 will remove her 5th tank set for STS-133 for weight savings.
No, the baseline is 3. The 4th and 5th are kits.
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#1111
by
Jim
on 29 Apr, 2010 00:53
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Why 102 and 105 -- did the fittings for the tank sets cost enough dry mass, or obstruct part of the payload bay, to make it worthwhile to spread around the capability? In practice, did the orbiters fly with less than their max # of tank sets? And, were the four sets in the EDO pallet the same in capacity to the standard four sets in each orbiter (ie, Atlantis could have doubled her duration had she ever flown with it, 102 and 105 a bit less)?
Thanks, -Alex
So they didn't have to go and put in and take out the tanks for different missions. 102 was the Spacelab vehicle.
There was no since in carrying the tanks when there no need for them and they would be dead mass.
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#1112
by
mkirk
on 29 Apr, 2010 01:06
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On some of the ascent launch videos around t -10 seconds i hear something that I think is "Nav init".
What does that mean and what is being performed / checked?
Also, right after liftoff both CDR and PLT say "auto" and "small numbers".
What are they referring to?
Thanks!
-Giles
Just to expand slightly on the explanation that DAVE S provided:
“NAV INIT” stands for nav initialization. At T-4 minutes the three IMU (inertial measurement unit) platforms are released and enter the inertial mode, however, they are not used for propagation of the state vector by the navigation software yet. That comes at T-11 seconds when the onboard computers [ Redundant Set Launch Sequencer (RSLS) as opposed to the Ground Launch Sequencer (GLS) ] command “NAV INIT”.
“AUTO AUTO” is a verification that the flight control system (FCS) is in the auto mode, this is checked by looking at the eyebrow panel (F2 & F4) lights for Pitch and Roll/Yaw – these two lights, labeled AUTO should be lit indicating the flight software is in Auto mode as opposed to CSS. CSS stands for control stick steering and is the manual mode of flying the orbiter.
“102, 102” refers to Major Mode 102 of the flight software. After coming out of the built-in-hold at T-20 minutes in the launch countdown the commander will mode the flight computers (GPCs or general purpose computers) to OPS 1 which is the operational sequence software for the countdown & launch. OPS 1 is divided into sub modes labeled 101, 102, 103 etc. 101 is used for the terminal countdown beginning at T-20 minutes. At SRB ignition the software is supposed to automatically transition to 102 (the software for first stage) on the primary (4 of them referred to as PASS) and backup (1 of them referred to as BFS) computers. At SRB ignition the commander will look at the CRTs, located on the forward instrument panels between the commander and pilot seats, he/she will verify that the title of one of the PASS displays has changed to 102 Ascent Traj and that the BFS computer screen says the same thing. 102 is the software used for first stage flight and 103 is used in second stage (beginning at SRB separation)
“NAV INIT”, “AUTO AUTO”, & “102 102” are calls that are usually made by the Commander. You will usually here the Pilot call “Engine start, three at 100” meaning that all three main engines have started and are at the commanded throttle level of 100% this is followed by another call just a few seconds after liftoff of “3 at 104” which indicates the three main engines have throttle up to the 104.5% level – this is commanded at ~T+4 seconds.
Mark Kirkman
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#1113
by
10W29
on 29 Apr, 2010 01:23
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Actually the baseline is 5 tank sets for all the vehicles.
OV-103 will remove her 5th tank set for STS-133 for weight savings.
No, the baseline is 3. The 4th and 5th are kits.
Which all the vehicles have. OK call it standard instead of baseline...semantics.
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#1114
by
Jim
on 29 Apr, 2010 01:55
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Which all the vehicles have. OK call it standard instead of baseline...semantics.
No, standard/baseline what ever, is 3 tank sets. 4 & 5 are options. They may have been left in for every ISS flight but they are not part of the standard orbiter. The documentation has to account for them being installed on each mission.
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#1115
by
iskyfly
on 29 Apr, 2010 13:52
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re: NAV INIT, Auto
Thank you very much DaveS and Mark.
Any idea on "Small numbers" ?
Thanks again!
-Giles
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#1116
by
10W29
on 29 Apr, 2010 22:53
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Which all the vehicles have. OK call it standard instead of baseline...semantics.
No, standard/baseline what ever, is 3 tank sets. 4 & 5 are options. They may have been left in for every ISS flight but they are not part of the standard orbiter. The documentation has to account for them being installed on each mission.
Tank Set 3 is a kit also.
Many installations are not "standard" but have always flown. Documentation is also required if they are removed.
Bottom line is all the remaining orbiters have flown 5 tank sets for >15 years. I was just correcting an error in which it was stated that 103 & 104 didn't have the 5th tank set.
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#1117
by
Jim
on 30 Apr, 2010 02:08
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Bottom line is all the remaining orbiters have flown 5 tank sets for >15 years. I was just correcting an error in which it was stated that 103 & 104 didn't have the 5th tank set.
<15 years, AXAF launched in 1999
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#1118
by
iskyfly
on 30 Apr, 2010 15:22
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#1119
by
mkirk
on 30 Apr, 2010 15:28
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re: NAV INIT, Auto
Thank you very much DaveS and Mark.
Any idea on "Small numbers" ?
Thanks again!
-Giles
"Small numbers" is not a formal callout, could be a reference to the MPS Helium Useage on the System Summary Display or ADI Error Digitals on the BFS Trajectory display, both of which should be small numbers.
I would have to know the context and who said it, can you point me to the particular video you heard this on?
Mark Kirkman