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#2740
by
Specifically-Impulsive
on 30 Nov, 2012 01:07
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There was some hefty ground equipment (on the pad), among other things, that get the SSMEs up and running.
What is this in reference to? The SSMEs started using head pressure from the ET and their own internal igniters. There was no special GSE related to SSME start except for the sparklers. There was, of course, GSE to fill and pressurize the ET, but none related to starting the SSMEs.
I have seen this misinformation posted several times and honestly wonder where it came from.
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#2741
by
Jim
on 30 Nov, 2012 01:41
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There was some hefty ground equipment (on the pad), among other things, that get the SSMEs up and running.
What is this in reference to? The SSMEs started using head pressure from the ET and their own internal igniters. There was no special GSE related to SSME start except for the sparklers. There was, of course, GSE to fill and pressurize the ET, but none related to starting the SSMEs.
There are the purges and the gas for them
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#2742
by
sivodave
on 11 Dec, 2012 21:25
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Hi all.
A quick question on the SRB. As part of the modification introduced post-Challenger there was the creation of a so called J-seal in lieu of the zinc chromate putty placed between the two motor segments insulation at the field joint.
The reason for adding such seal, was to avoid imperfection (ie: air pockets) in the injection of such potty which could create an easy way for the exhaust to find their way to the joint. However, based on the attached schematics, it seems to me that this configuration had a weak point in the form of a little corner in the slot cut in the insulation. In fact, the small radius corner would constitute stress concentration point for the high pressure-high temperature exhaust for pushing through the insulation and carving the slot further up to the joint.
Does all of this make sense? Where am I wrong in my thinking?
Thanks very much
Davide
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#2743
by
Fequalsma
on 11 Dec, 2012 22:47
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The purpose of the J-seal was to add another level of protection for the field joint against the hot gas. During assembly, the free leg of the J-seal was glued to the opposite face of the adjoining SRM segment. When the SRB ignited, the hot gas pressurized the open end of the J-seal and forced it to open wider and seal better. The hot gas was trapped in the dead end, and could not reach the field joint and O-rings.
F=ma
Hi all.
A quick question on the SRB. As part of the modification introduced post-Challenger there was the creation of a so called J-seal in lieu of the zinc chromate putty placed between the two motor segments insulation at the field joint.
The reason for adding such seal, was to avoid imperfection (ie: air pockets) in the injection of such potty which could create an easy way for the exhaust to find their way to the joint. However, based on the attached schematics, it seems to me that this configuration had a weak point in the form of a little corner in the slot cut in the insulation. In fact, the small radius corner would constitute stress concentration point for the high pressure-high temperature exhaust for pushing through the insulation and carving the slot further up to the joint.
Does all of this make sense? Where am I wrong in my thinking?
Thanks very much
Davide
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#2744
by
alk3997
on 12 Dec, 2012 01:18
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Anyone know if the pre-launch aerosurface check (T-3:55) and gimbal check (T-3:25) is commanded by the GLS or is it the RSLS that commands those?
Dave, that was commanded by the GLS. We had to simulate the GLS when testing the RSLS. The GLS left the engines in their start-up position when completed with the checks.
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#2745
by
DaveS
on 12 Dec, 2012 01:24
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Anyone know if the pre-launch aerosurface check (T-3:55) and gimbal check (T-3:25) is commanded by the GLS or is it the RSLS that commands those?
Dave, that was commanded by the GLS. We had to simulate the GLS when testing the RSLS. The GLS left the engines in their start-up position when completed with the checks.
Thanks. Just to be certain: The GLS did all the commanding from T-9 minutes to RSLS Autosequence Start at T-31 seconds?
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#2746
by
alk3997
on 12 Dec, 2012 04:36
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No. RSLS was running from T-9 minutes on down. Things like the orbiter vent doors were commanded by RSLS (I believe we changed the timing after the STS-30 hold at T-50-some seconds) which was at one time before T-31 seconds. The Go for Autosequence was simply a flag that said to proceed past T-31 seconds.
So not so cut and dry as saying all commanding was done by GLS. Most (almost all) is probably correct.
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#2747
by
sivodave
on 13 Dec, 2012 21:13
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Hi all.
I was reading some posts posted few posts ago, in particular this reply concerning the tiles sourrounding the hatch:
The tiles are bonded to thin metal plates, which are screwed to the rest of the hatch structure. The plates cover the access's to the hatch locking mechanism and other things (like the inspection port they stick a borescope thru to check and make sure the latches have all engaged). The plates have to be installed after the hatch is closed, so the tiles have holes thru them to allow the fastenesr to be inserted. The bright white stuff is a filler compound that is stuffed over the fastener heads to protect them.
Does this really mean that those tiles were manually screwed on the Orbiter just few hours before launch? it seems to me that there is quite a good number of such tiles had to be installed at the "last minute".
Did they also have to unscrew everything once the Orbiter was back home to allow the astronaut to exit? Regarding this question, I would say no since in case of emergency the astronauts could open the hatch by themself from the inside, right?
Thanks
Davide
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#2748
by
JayP
on 19 Dec, 2012 12:45
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Hi all.
I was reading some posts posted few posts ago, in particular this reply concerning the tiles sourrounding the hatch:
The tiles are bonded to thin metal plates, which are screwed to the rest of the hatch structure. The plates cover the access's to the hatch locking mechanism and other things (like the inspection port they stick a borescope thru to check and make sure the latches have all engaged). The plates have to be installed after the hatch is closed, so the tiles have holes thru them to allow the fastenesr to be inserted. The bright white stuff is a filler compound that is stuffed over the fastener heads to protect them.
Does this really mean that those tiles were manually screwed on the Orbiter just few hours before launch? it seems to me that there is quite a good number of such tiles had to be installed at the "last minute".
Did they also have to unscrew everything once the Orbiter was back home to allow the astronaut to exit? Regarding this question, I would say no since in case of emergency the astronauts could open the hatch by themself from the inside, right?
Thanks
Davide
Yes installing those panels was the very last vehicle close outs done before launch. After that, they closed out the white room and evacuated the pad. Those were the only TPS closeouts done in the final countdown. everything else was done before fueling.
Also yes, those panels were the first things removed by the ground crew after they got the mobile white room in place on the runway. The crew could open the hatch from the inside but that was never done since that would involve basically "droping" the hatch dowanward to the 90 degree open position which would strain the hinges considerably. Removing the panels alowed the ground crew to atach the external handle and support the hatch as it lowered (as well as give them access to the latch drive mechanism).
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#2749
by
cautionjump
on 22 Dec, 2012 23:00
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Hello everyone!
I just joined L2 Premium and love all the high res photos! I have this cable that is documented as being a data cable flown on 134 for the STORRM experiment.
I looked at all the photos on NASAs site of the mission and was unable to find the cable although there were similar ones. What makes this one unique is it has orange stripes on the label. Does anyone know why they labels are striped when no others in the cabin are? Is it a back up cable? Where would it be located?
Heres a photo and the labels.
"STORRM RS-422 DATA Cable"
Model number 528-21526-1
Serial 1005
Ends are labeled
"Vision Navigation Sensor"
"PDO"
"Spare 1"
"Docking Camera"
Is this the best section to ask this or should I move it else where? Thanks!
Eric
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#2750
by
Jim
on 23 Dec, 2012 00:01
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Post a photo or pdf of your documentation.
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#2751
by
cautionjump
on 23 Dec, 2012 23:01
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Ill try and find the paper work on it, its interesting because I was able to find an identical cable plugged into a flight laptop, but that cable had yellow tags on it and didnt have the orange stripes, so im thinking maybe it was a back up cable that was flown on the mission...
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#2752
by
Jim
on 23 Dec, 2012 23:02
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It could be a training cable
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#2753
by
cautionjump
on 24 Dec, 2012 01:43
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Yeah it does say on the paperwork it was removed from stock and "ok for for STS 134". It was a surplus government auction which also notes it from STS 134...
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#2754
by
Chris Bergin
on 24 Dec, 2012 12:24
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#2755
by
cautionjump
on 24 Dec, 2012 16:41
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Thank you for the links, the information was very helpful! It seems to verify what I thought, that the cable connects the PGCS to the orbiter, and it appears only one PGCS computer was connected to the STORRM system.
So I guess if I could find out why the labels have the orange stripping it would explain why that cable was made and flown on Endeavour, but not hooked up to a PGCS laptop. My best guess is that it was a back up at this point, unless anyone know for sure of ca point me in the direction of some documentation that I can look through for an answer on the cabling used on flights...
Thanks again for everyone's help!
Eric
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#2756
by
Jim
on 24 Dec, 2012 18:37
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My best guess is that it was a back up at this point, unless anyone know for sure of ca point me in the direction of some documentation that I can look through for an answer on the cabling used on flights...
Thanks again for everyone's help!
Eric
You would need the installation procedure to determine which serial number of the cable flew. You would need an FOIA request.
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#2757
by
alk3997
on 26 Dec, 2012 01:05
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First it is a PGSC - Payload and General Support Computer. That was for a DTO, so it was not a standard PGSC cable. It was created for that specific DTO. You would probably need to talk with the DTO principle investigator for the answer on specific uses of this cable. The round cannon-type plug looks like one that would connect to a control panel. The DB-9 plugs (or DB-15) were the RS-422 data cables.
Other than that I'd need to see the drawing to tell more. The yellow stripes could also indicate a ground version or a training version or a certification version. You would have to reference the cable serial number to the flight manifest to determine if the cable was flown.
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#2758
by
mgfitter
on 27 Dec, 2012 23:30
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Is there any information available detailing how much LOX and LH2 was lost to boil-off during the Shuttle Program, either per year or per launch?
I know each launch required about 735,000kg at lift-off, but I'm curious how much more was needed to support each launch and also how much was needed just to keep the cryo-tanks conditioned correctly between flights?
Does anyone know?
-MG.
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#2759
by
AnalogMan
on 28 Dec, 2012 00:50
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Is there any information available detailing how much LOX and LH2 was lost to boil-off during the Shuttle Program, either per year or per launch?
I know each launch required about 735,000kg at lift-off, but I'm curious how much more was needed to support each launch and also how much was needed just to keep the cryo-tanks conditioned correctly between flights?
Does anyone know?
Some info on LH2 use recently posted by NASA/KSC which may be of partial help on a per-launch basis:
"The supply of LH2 at KSC LC39B currently is provided by over the road tankers from Louisiana. Past Space Shuttle launches have required that an existing 850,000 gallon storage tank located at LC39B be filled by this method prior to the start of LH2 tanking operations. Replenish losses were 12.6%, evaporation losses were 12.2%, normal launch loss was 12.9%, and launch scrub with 24 hour turnaround was 7.8%."Did not mention between-launch consumption.
