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#1440
by
Jim
on 12 Nov, 2010 18:05
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I stand corrected
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#1441
by
Lee Jay
on 12 Nov, 2010 18:18
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Thanks Lee!
I guess the trouble of cooling a rocket to keep the fuel liquid just would be too cumbersome to make it practical or worthwhile?
It could be done in theory with Helium as the working fluid. The trouble is, taking heat out of a 4K gas takes a huge system and a huge amount of energy, especially if there is a large volume of gas to be re-condensed. This volume can be drastically reduced by really good insulation of the vessel (i.e. vacuum), but that makes the vessel heavy. Since the ET has to be taken to near-orbital velocity, the insulation has to be light, and thus not very good. So there's a lot of gas volume and that means a really, really huge cooling system - so huge as to be impractical. So they do KISS and just remove the gas and flare it off.
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#1442
by
Sesquipedalian
on 14 Nov, 2010 01:38
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From the shuttle processing threads, it sounds like they are doing NDE of the stringers from inside the intertank. How does that work? Do they have a guy clambering around on top of the dome of the LH2 tank?
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#1443
by
Jim
on 14 Nov, 2010 09:44
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From the shuttle processing threads, it sounds like they are doing NDE of the stringers from inside the intertank. How does that work? Do they have a guy clambering around on top of the dome of the LH2 tank?
There is an access door and internal platforms that can be installed.
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#1444
by
craigcocca
on 14 Nov, 2010 17:12
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Is there any possibility that the stringer cracks seen on ET-137 have been the root cause of the ET foam liberation issues all along? I know that the root cause had been chalked up to cryopumping long ago, but perhaps these small cracks in the Al-Li stringers have been cropping up when the tank is chilled down, but have gone unnoticed because the tank structure is usually not inspected after tanking?
I am not making an expert claim here...rather, I am asking the experts to tell me if there is any merit to this hypothesis.
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#1445
by
DaveS
on 15 Nov, 2010 11:33
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Here's a question for the GN&C experts around here:
What does the shuttle GN&C software look at during entry to command the roll reversals? I know that the rolls are closed-loop guidance commanded so it must be some dynamic values that it looks at and decides it time to command a roll in one direction or the other.
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#1446
by
Sesquipedalian
on 16 Nov, 2010 02:57
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#1447
by
Jorge
on 16 Nov, 2010 03:10
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I had to do a double-take at this picture on Wikipedia:
http://upload.wikimedia.org/wikipedia/commons/f/fe/STS-103_Hubble_EVA.jpg
This is from STS-103/Discovery, a Hubble servicing mission. But that thing in the foreground sure looks like an Orbiter Docking System. Why is it there -- did NASA just not bother to remove it between ISS flights?
Since NASA removed the internal airlocks from the orbiters, the ODS airlock doubles as the EVA airlock for shuttle-based EVAs. The APAS can be removed from the top of the ODS (and was, for STS-125) but it was not necessary to remove it for STS-103, so it remained.
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#1448
by
Jorge
on 16 Nov, 2010 03:21
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Here's a question for the GN&C experts around here:
What does the shuttle GN&C software look at during entry to command the roll reversals? I know that the rolls are closed-loop guidance commanded so it must be some dynamic values that it looks at and decides it time to command a roll in one direction or the other.
Delta-azimuth (DEL-AZ), the angle between the velocity vector and the vector to the tangent on the HAC. A roll reversal is performed when DEL-AZ exceeds a velocity-dependent value.
The Entry Guidance workbook on L2 explains this, also:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790075283_1979075283.pdf
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#1449
by
Sesquipedalian
on 16 Nov, 2010 06:43
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Since NASA removed the internal airlocks from the orbiters, the ODS airlock doubles as the EVA airlock for shuttle-based EVAs. The APAS can be removed from the top of the ODS (and was, for STS-125) but it was not necessary to remove it for STS-103, so it remained.
Cool, thanks. I remember reading notes on L2 about Atlantis's ODS being reinstalled after STS-125, which is why I was confused.
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#1450
by
sdsds
on 16 Nov, 2010 23:19
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This image is so cool! It is apparently the inside of the STS-133 intertank. It certainly gives the impression the LOX tank is is directly supported by the thrust beam. Is that correct?
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#1451
by
robertross
on 16 Nov, 2010 23:27
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This image is so cool! It is apparently the inside of the STS-133 intertank. It certainly gives the impression the LOX tank is is directly supported by the thrust beam. Is that correct?
Nope. That's done from the tank's outer wall.
The thrust beam just transmits the loads from the two SRBs.
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#1452
by
jeff122670
on 17 Nov, 2010 01:59
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I cant get over how close both tanks are....I dont know what I was picturing in my mind, but WOW, they are close!! Thanks for the pic!!
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#1453
by
chrisking0997
on 17 Nov, 2010 02:04
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trying to get perspective on that pic....how tall is the thrust beam (the part we are looking at)?
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#1454
by
kraisee
on 17 Nov, 2010 02:20
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trying to get perspective on that pic....how tall is the thrust beam (the part we are looking at)?
According to the SLWT SDH:
"The SRB beam assembly is a rectangular box beam. It is 42.95 inches deep at the center and tapers to 26 inches (at the ends) by 15 inches wide, and spans 345 inches between the centerlines of the two SRB thrust fittings which form the ends of the assembly."
The beam is designed to be able to flex up & down, by to 6" during flight, in order to dampen the vibrations normally created by the SRB's (what you and I know as "Thrust Oscillation").
You can clearly see one of the SRB beams in this memorable image from 2003:
http://science.ksc.nasa.gov/gallery/photos/2003/captions/KSC-03PD-3154.htmlRoss.
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#1455
by
robertross
on 17 Nov, 2010 02:22
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trying to get perspective on that pic....how tall is the thrust beam (the part we are looking at)?
(paraphrasing): "42.95 inches deep at the center, and tapers to 26" at the ends, 15" wide, and spans 345" between the centerlines of the SRB thrust fittings..."
Also, the 'SLWT catalog' indicates "The crossbeam deflections are limited since the dynamic clearance between the thrust beam and the LO2 & LH2 domes are small"
awww...Ross beat me to it
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#1456
by
chrisking0997
on 17 Nov, 2010 16:47
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thanks!
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#1457
by
Ronsmytheiii
on 18 Nov, 2010 15:38
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On several sources on the internet, the SSME has both the numeric designations RS-24 and RS-25. Is there any difference between the two, and why the dual designation?
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#1458
by
ChrisGebhardt
on 18 Nov, 2010 15:50
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#1459
by
DaveS
on 21 Nov, 2010 14:31
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The LOX anti-geyser line on the SWTs, did it connect to the aft vertical strut or the elbow of the LOX feedline?
