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#2040 by Sesquipedalian on 11 Jul, 2011 17:56
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Sorry if this is the wrong place to post this, but I have a question about the net mass of the MPLM cargo on this mission. The Flight Operations and Integration PDF on L2 lists the mass of the MPLM as 25,478 lbs up, and this page indicates that the empty mass of an MPLM is 9000 lbs, so the cargo should be 16,478 lbs. However this article says that the MPLM cargo came to 9,403 lbs. Where is the discrepancy?
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#2041 by vsrinivas on 11 Jul, 2011 18:49
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Wow, what a thread!
A pair of questions for people who might know the PASS...
First, I've read that early in Shuttle's life, the on-orbit autopilot would overuse the vernier RCS jets; was anything ever done about that? How are the vernier RCS jets selected now?
Second, why does (wow I can still say that, for just a little longer) the transitional autopilot not use a state estimator/kalman filter?
Thanks, -
#2042 by plomaris on 12 Jul, 2011 17:33
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Does anyone have any details on the debris seen right after SRB Separation (at about 2:15)? From the launch video ET camera view, it looks like an yellow/orange piece of cloth or tape that leaves the starboard side of the orbiter in the chine area and gets whirled back over the starboard wing (see pics). It does not appear to strike the orbiter.
I've been listening to all the updates and haven't heard any mention of this event. Normally after launch, all debris events are covered in news conferences, but I've heard no mention of this one. I'm sure I'm not the only one to have seen it.
Just replay the launch video and watch in slow motion right after SRB sep.
Anyone else see it?
Tom
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#2043 by psloss on 12 Jul, 2011 17:35
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That's OMS assist ignition.
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#2044 by ugordan on 12 Jul, 2011 17:35
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That just looks like an OMS assist start transient.
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#2045 by plomaris on 12 Jul, 2011 17:41
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Thanks for the quick reply. I guess I never paid such close attention before.
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#2046 by STS-134 on 12 Jul, 2011 18:58
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Why do they always fire the OMS engines on the way up? Aren't those only supposed to be for maneuvering once in orbit? Why not just use up the SSME propellant (by pushing MECO back a bit) and save the OMS propellant for later?
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#2047 by Jim on 12 Jul, 2011 19:09
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Why do they always fire the OMS engines on the way up? Aren't those only supposed to be for maneuvering once in orbit? Why not just use up the SSME propellant (by pushing MECO back a bit) and save the OMS propellant for later?
They know how much they need for each mission with margin and burn off the excess. There is a performance benefit by doing this.
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#2048 by elmarko on 13 Jul, 2011 08:41
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I remember asking about this ages ago. I was surprised that they actually got such a good boost from the OMS engines, as opposed to just not loading that propellant in the first place.
Why do they always fire the OMS engines on the way up? Aren't those only supposed to be for maneuvering once in orbit? Why not just use up the SSME propellant (by pushing MECO back a bit) and save the OMS propellant for later?
They know how much they need for each mission with margin and burn off the excess. There is a performance benefit by doing this. -
#2049 by Jim on 13 Jul, 2011 12:10
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I remember asking about this ages ago. I was surprised that they actually got such a good boost from the OMS engines, as opposed to just not loading that propellant in the first place.
Why do they always fire the OMS engines on the way up? Aren't those only supposed to be for maneuvering once in orbit? Why not just use up the SSME propellant (by pushing MECO back a bit) and save the OMS propellant for later?
They know how much they need for each mission with margin and burn off the excess. There is a performance benefit by doing this.
It isn't the thrust as much but the loss of mass. -
#2050 by spacecane on 13 Jul, 2011 22:00
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Does anybody have a list of all the acronyms used on the radio loop during the shuttle countdown. There were so many I can't remember them all. The ones I figured out (or think I did) were:
CDR - Commander
PLT - Pilot
MS1 - Mission Specialist 1
MS2 - Mission Specialist 2
MMT - Mission Management Team
SRO - Safety Range Officer (thought it was RSO)
But there were many others that I didn't catch or couldn't figure out like NTD.
Not that we'll ever hear a Shuttle countdown again but I was curious who all the acronyms referred to. -
#2051 by Chris Bergin on 13 Jul, 2011 22:04
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Does anybody have a list of all the acronyms used on the radio loop during the shuttle countdown. There were so many I can't remember them all. The ones I figured out (or think I did) were:
CDR - Commander
PLT - Pilot
MS1 - Mission Specialist 1
MS2 - Mission Specialist 2
MMT - Mission Management Team
SRO - Safety Range Officer (thought it was RSO)
But there were many others that I didn't catch or couldn't figure out like NTD.
Not that we'll ever hear a Shuttle countdown again but I was curious who all the acronyms referred to.
Someone doesn't read my articles then
NTD Is NASA Test Director (NTD). I've used that in about 100 articles.
Moving to Shuttle Q&A -
#2052 by DaveS on 13 Jul, 2011 22:37
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Does anybody have a list of all the acronyms used on the radio loop during the shuttle countdown. There were so many I can't remember them all. The ones I figured out (or think I did) were:
SRO = Superintendent of Range Ops
CDR - Commander
PLT - Pilot
MS1 - Mission Specialist 1
MS2 - Mission Specialist 2
MMT - Mission Management Team
SRO - Safety Range Officer (thought it was RSO)
But there were many others that I didn't catch or couldn't figure out like NTD.
Not that we'll ever hear a Shuttle countdown again but I was curious who all the acronyms referred to.
NTD = NASA Test Director
LD = Launch Director
OTC = Orbiter Test Conductor
SPE = Shuttle Project Engineer
LRD = Landing/Recovery Director
BTC = Booster/Tank Test Conductor
PTC = Payload Test Conductor
LPS = Launch Processing System
STM = Site Test Manager
CGLS = Ground Launch Sequencer
OPE = Orbiter Project Engineer
CLHY = Liquid Hydrogen console
CLOX= Liquid Oxygen console
CAPU = Auxiliary Power Unit console
CMPS = Main Propulsion System console
CHYD = Orbiter(??) Hydraulics console
CHGD = Hazardous Gas Detection console
That's all that comes to mind right now but there are many more. -
#2053 by Sesquipedalian on 13 Jul, 2011 22:47
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Bumping my earlier question...
Sorry if this is the wrong place to post this, but I have a question about the net mass of the MPLM cargo on this mission. The Flight Operations and Integration PDF on L2 lists the mass of the MPLM as 25,478 lbs up, and this page indicates that the empty mass of an MPLM is 9000 lbs, so the cargo should be 16,478 lbs. However this article says that the MPLM cargo came to 9,403 lbs. Where is the discrepancy?
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#2054 by elmarko on 14 Jul, 2011 09:41
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Don't we have a document somewhere with a huuuuuge list of them in? I'm sure I've downloaded it from NSF before.
Also NASA have a list online on their public website somewhere.Does anybody have a list of all the acronyms used on the radio loop during the shuttle countdown. There were so many I can't remember them all. The ones I figured out (or think I did) were:
CDR - Commander
PLT - Pilot
MS1 - Mission Specialist 1
MS2 - Mission Specialist 2
MMT - Mission Management Team
SRO - Safety Range Officer (thought it was RSO)
But there were many others that I didn't catch or couldn't figure out like NTD.
Not that we'll ever hear a Shuttle countdown again but I was curious who all the acronyms referred to.
Someone doesn't read my articles then NTD Is NASA Test Director (NTD). I've used that in about 100 articles.
Moving to Shuttle Q&A -
#2055 by spacecane on 14 Jul, 2011 14:29
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Why is the "neutral" thrust vector of the SSMEs angled relative to the stack? I've always wondered why they were set up to where they are sort of pushing the orbiter towards the ET. I assume that because of this the stack doesn't travel exactly in the direction the nose is pointing?
Is it just because they needed room to be able to gimble "down" (towards bottom of orbiter) without interference from the body flap or are there other reasons? -
#2056 by Jim on 14 Jul, 2011 15:12
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Why is the "neutral" thrust vector of the SSMEs angled relative to the stack? I've always wondered why they were set up to where they are sort of pushing the orbiter towards the ET. I assume that because of this the stack doesn't travel exactly in the direction the nose is pointing?
they are pointed at the CG of the stack. -
#2057 by elmarko on 14 Jul, 2011 18:36
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What happens after SRB and ET separation? It changes and so the orbiter has to make burns at a weird orientation?
Why is the "neutral" thrust vector of the SSMEs angled relative to the stack? I've always wondered why they were set up to where they are sort of pushing the orbiter towards the ET. I assume that because of this the stack doesn't travel exactly in the direction the nose is pointing?
they are pointed at the CG of the stack. -
#2058 by Jorge on 14 Jul, 2011 18:39
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What happens after SRB and ET separation? It changes and so the orbiter has to make burns at a weird orientation?
Why is the "neutral" thrust vector of the SSMEs angled relative to the stack? I've always wondered why they were set up to where they are sort of pushing the orbiter towards the ET. I assume that because of this the stack doesn't travel exactly in the direction the nose is pointing?
they are pointed at the CG of the stack.
The SSMEs gimbal to handle the transient at SRB sep. If you watch the ET camera you can see that it's small and controllable, not a "weird orientation" at all.
ET sep is not an issue since MECO occurs before then. -
#2059 by tminus9 on 14 Jul, 2011 19:29
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What happens after SRB and ET separation? It changes and so the orbiter has to make burns at a weird orientation?
Why is the "neutral" thrust vector of the SSMEs angled relative to the stack? I've always wondered why they were set up to where they are sort of pushing the orbiter towards the ET. I assume that because of this the stack doesn't travel exactly in the direction the nose is pointing?
they are pointed at the CG of the stack.
The SSMEs gimbal to handle the transient at SRB sep. If you watch the ET camera you can see that it's small and controllable, not a "weird orientation" at all.
ET sep is not an issue since MECO occurs before then.
How much does the stack CG shift (1) during first stage, (2) at SRB sep, and (3) during second stage? Presumably most of the shift is in x as the LO2 and LH2 are depleted?
NTD Is NASA Test Director (NTD). I've used that in about 100 articles.