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#540
by
Austin
on 13 Dec, 2006 23:33
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psloss - 13/12/2006 4:06 PM
Austin - 13/12/2006 6:02 PM
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
SSME 1 = center
SSME 2 = left
SSME 3 = right
Ah! That makes sense now. Thanks Philip
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#541
by
psloss
on 13 Dec, 2006 23:36
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#542
by
Starks
on 14 Dec, 2006 08:28
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Do astronauts get Internet or email in space?
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#543
by
Jim
on 14 Dec, 2006 11:41
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Starks - 14/12/2006 4:11 AM
Do astronauts get Internet or email in space?
yes
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#544
by
elmarko
on 14 Dec, 2006 11:44
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No access to public internet?
It'd be cool to be on a forum and just post "Oh hi I'm in space LOL"
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#545
by
Jim
on 14 Dec, 2006 12:15
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elmarko - 14/12/2006 7:27 AM
No access to public internet?
It'd be cool to be on a forum and just post "Oh hi I'm in space LOL"
System isn't set up for that
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#546
by
mkirk
on 14 Dec, 2006 14:56
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Austin - 13/12/2006 5:02 PM
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
I think everyone would have been very impressed if Andy had been referring to the SRBs since there really isn’t any onboard insight into SRB chamber pressures.
There are pressure transducers in each SRB that the Booster Officer in Mission Control can see that show the chamber pressure in pounds per square inch. At the SRB test firing last month in Utah they had an advanced pressure transducer they were testing which would provide an additional redundant measurement of the chamber pressure.
On the Orbiter the only cue the crew has is a flashing yellow overbright “PC<50” on the ASCENT TRAJECTORY display just before SRB separation. This tells the crew that the chamber pressure in both boosters has fallen below 50 psi and that for all practical purposes the SRBs have burned out and are no longer producing significant forward thrust. This cue means it is safe to separate from the boosters.
Mark Kirkman
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#547
by
kneecaps
on 14 Dec, 2006 22:06
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mkirk - 12/12/2006 5:51 PM
kneecaps - 11/12/2006 7:45 PM
Thanks Mark,
Now that makes sense, I think the booster systems brief has thrown me off track somewhere...it shows in purge Seq 3 GN2 purges into the turbopumps exiting via the turbopump drains....and in Seq 4 the PCA switches this to Helium.....prehaps i'm misunderstanding (plenty of pitfalls in comprehension of the SSME i've discovered).
Or could this be happening in addition to the O2 flow in through the oxygen manifold --> prevalves ---> turbopumps?
You basically have Hydrogen, Oxygen, Nitrogen, and Helium flowing through the engine during the various purges. The purpose of all of the purges is to thermally condition the engine and components, dry the engine in the case of the GN2, and maintain a positive pressure to prevent contamination of the lines with dust and moisture. The heilum is used on the fuel side because nitrogen would freeze at the cryogenic temperatures of the LH2. After tanking starts the Bleed valves allow the flow of hydrogen and oxygen within their respective systems as well in conjunction with the the helium/nitrogen flows.
The flow rate increases for the fuel system purge (i.e. the H2 side) during Purge Sequence 4. Another difference is that helium is used in bursts during sequence 3 and 4 for the intermediate seal (IMSL) purge. The idea with the IMSL is to keep the H2 and O2 separate…this is more critical during engine operation when hot hydrogen rich gas is used to drive the High Pressure Oxidizer Turbopump which is used to flow cold liquid oxygen.
Also FYI, the copy of the Booster Systems Brief you are using only covers section 1, there are 7 other sections which discuss all of the plumbing in the MPS, ET Systems and Tanking Operations, SRB systems, and Cryo theory.
Mark Kirkman
Thanks again Mark! Thats cleared it up somewhat for me!! I have to get my head around the bleed valves. We only have section one of the booster systems brief? There is more? Much more! FANTASTIC, thanks for that pointer
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#548
by
psloss
on 14 Dec, 2006 22:10
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psloss - 12/12/2006 7:32 PM
psloss - 12/12/2006 6:41 PM
The noise I'm referring to occurs "once" more or less -- right at T-4 minutes, which is why I always associated with the GLS milestone and call from the console operator that followed it...I'll see if I can pull together a few audio clips.
It doesn't sound to me like the APUs, but that's why I'm curious, because it doesn't sound to me like the APUs.
Commentary or just not having the sound at the pad mixed that high often makes it hard to hear this sound or inaudible to me.
Actually not that difficult to find a few examples of what I'm hearing, but even as audio clips they're too big to attach here, so I'll see about posting the video excerpts on L2 in a little bit and seeing if you folks can identify what the sound is...
In case anyone is interested in this besides me, I'll post these sometime after STS-116 when things are a little quieter.
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#549
by
Austin
on 14 Dec, 2006 23:20
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mkirk - 14/12/2006 7:39 AM
Austin - 13/12/2006 5:02 PM
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
I think everyone would have been very impressed if Andy had been referring to the SRBs since there really isn’t any onboard insight into SRB chamber pressures.
There are pressure transducers in each SRB that the Booster Officer in Mission Control can see that show the chamber pressure in pounds per square inch. At the SRB test firing last month in Utah they had an advanced pressure transducer they were testing which would provide an additional redundant measurement of the chamber pressure.
Mark Kirkman
...And I suppose there really would not be a reason for an onboard display to gauge SRB chamber pressure anyway (aside from the PC<50 precurser to staging) since unlike the engines, they cannot be throttled back or shut off, even if there was a sudden reduction in thrust.
As Ron McNair once (fatefully) said, if something goes wrong during the first two minutes of flight, "you either ride it out or go down with the ship."
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#550
by
PMN1
on 16 Dec, 2006 19:01
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The amount of fuel needed will have dictated the final size of the ET but what dictated the final diameter?
What was to stop it being shorter but of greater diameter or longer but of reduced diameter?
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#551
by
hyper_snyper
on 16 Dec, 2006 19:01
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Weight and aerodynamics I would assume. Maximize the fuel carried but minimize the weight (material used).
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#552
by
GoForTLI
on 17 Dec, 2006 02:41
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I have a question regarding the spacecraft tracking map in the FCR. I was watching EVA3 on STS-116 during the activities to retract the 4B wing of the P6 solar array. Actions and troubleshooting depended on KU-band coverage and whether or not the vehicle was in daylight. It looks like the spacecraft experiences orbital sunrise before crossing the day/night indicator on the display, and experiences sunset after crossing back to night on the display. In other words, it looks to me like the display indicates the location of the terminator on the Earth, and not where the vehicle will be over the Earth when it experiences a sunrise or sunset (which would depend on the altitude of the vehicle).
Wouldn't it make more sense for the display to indicate when vehicle sunrise or sunset occurs? I would think orbital sunrise/sunset data would be much more valuable to a flight controller than the location of the terminator.
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#553
by
Jim
on 17 Dec, 2006 03:40
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GoForTLI - 16/12/2006 10:24 PM
I have a question regarding the spacecraft tracking map in the FCR. I was watching EVA3 on STS-116 during the activities to retract the 4B wing of the P6 solar array. Actions and troubleshooting depended on KU-band coverage and whether or not the vehicle was in daylight. It looks like the spacecraft experiences orbital sunrise before crossing the day/night indicator on the display, and experiences sunset after crossing back to night on the display. In other words, it looks to me like the display indicates the location of the terminator on the Earth, and not where the vehicle will be over the Earth when it experiences a sunrise or sunset (which would depend on the altitude of the vehicle).
Wouldn't it make more sense for the display to indicate when vehicle sunrise or sunset occurs? I would think orbital sunrise/sunset data would be much more valuable to a flight controller than the location of the terminator.
There are brackets " [ " and "]" on the orbital track that indicate when the vehicle enters and leaves sunlight
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#554
by
shuttlefan
on 17 Dec, 2006 05:20
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Austin - 14/12/2006 6:03 PM
mkirk - 14/12/2006 7:39 AM
Austin - 13/12/2006 5:02 PM
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
I think everyone would have been very impressed if Andy had been referring to the SRBs since there really isn’t any onboard insight into SRB chamber pressures.
There are pressure transducers in each SRB that the Booster Officer in Mission Control can see that show the chamber pressure in pounds per square inch. At the SRB test firing last month in Utah they had an advanced pressure transducer they were testing which would provide an additional redundant measurement of the chamber pressure.
Mark Kirkman
...And I suppose there really would not be a reason for an onboard display to gauge SRB chamber pressure anyway (aside from the PC<50 precurser to staging) since unlike the engines, they cannot be throttled back or shut off, even if there was a sudden reduction in thrust.
As Ron McNair once (fatefully) said, if something goes wrong during the first two minutes of flight, "you either ride it out or go down with the ship."
Do the astronauts spend alot of time learning about the systems on the SRBs, as they have no control over them anyway?
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#555
by
Jim
on 17 Dec, 2006 13:22
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no, not really
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#556
by
Avron
on 17 Dec, 2006 15:39
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I was wondering what the avg pay of an astronaut was?
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#557
by
Jorge
on 18 Dec, 2006 05:41
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Avron - 17/12/2006 10:22 AM
I was wondering what the avg pay of an astronaut was?
Astronauts are paid according to the standard Civil Service scale. These scales are available on the web. Astronauts are in the GS-11 to GS-14 grades. The average annual pay is somewhere in the $80k range.
--
JRF
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#558
by
rfoshaug
on 18 Dec, 2006 10:19
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Sorry if this has been asked before, but here goes:
Today, Curbeam will perform his 4th EVA on a single mission. What is the record of number of EVA's on a single flight by the same crewmember? I guess this goes for the entire history of manned spaceflight, too, has there ever been a mission when a crewmember has performed 4 EVA's or more on the same mission?
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#559
by
rfoshaug
on 18 Dec, 2006 10:20
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I guess, if you count the "stand up EVA", that Dave Scott did 4 EVA's on Apollo 15.
