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#40
by
dember
on 11 Dec, 2007 19:34
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Great article.
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#41
by
rdale
on 11 Dec, 2007 19:36
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Bench tests of equipment will be held at the manufacturers, in parallel with tanking test.
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#42
by
Mark Max Q
on 11 Dec, 2007 19:37
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rdale - 11/12/2007 2:34 PM
Really all he did was rehash Chris' main story, on to questions already.
I was just thinking that :laugh:
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#43
by
rdale
on 11 Dec, 2007 19:38
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David (?) from NHK wanted to know when the testing would be complete.
How Wayne held back amazes me...
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#44
by
rdale
on 11 Dec, 2007 19:41
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Won't look at any LCC changes until troubleshooting complete.
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#45
by
Maverick
on 11 Dec, 2007 20:04
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Chris Bergin - 11/12/2007 10:34 AM
We have the presentation etc on L2, which is being presented to the PRCB right now, and I've done a quick overview of the forward plan (more to come):
http://www.nasaspaceflight.com/content/?cid=5306
A several hours later, it was like Wayne Hale was reading from it with the plan
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#46
by
shuttlefan
on 11 Dec, 2007 20:59
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So will the ET just be loaded with LH2 or LH2 and LOX?
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#47
by
jimmiemac
on 11 Dec, 2007 21:17
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shuttlefan - 11/12/2007 1:59 PM
So will the ET just be loaded with LH2 or LH2 and LOX?
Looks like LH2 only. From
http://www.nasa.gov/mission_pages/shuttle/main/index.html"Technicians and engineers in NASA's space shuttle program plan to test the engine cutoff sensor system onboard space shuttle Atlantis by pumping super-cold liquid hydrogen into the external fuel tank. The test is tentatively planned for Dec. 18. It will be conducted at the launch pad at Kennedy Space Center where Atlantis remains poised for launch"
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#48
by
Bubbinski
on 11 Dec, 2007 21:44
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How does this partial fuel load affect the number of launch attempts the tank is good for? I've been under the impression from reading this forum that the shuttle ET is certified for 13 cycles - 6 or 7 launch attempts. The ET has been fueled twice already, the tanking test would make it 3 times.
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#49
by
psloss
on 11 Dec, 2007 21:51
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Bubbinski - 11/12/2007 5:44 PM
How does this partial fuel load affect the number of launch attempts the tank is good for? I've been under the impression from reading this forum that the shuttle ET is certified for 13 cycles - 6 or 7 launch attempts. The ET has been fueled twice already, the tanking test would make it 3 times.
Tanking counts as one cycle, pressurization counts as another, so they could theoretically tank more than 6 or 7 times as long as they don't repeatedly go inside LO2 tank pressurization at a little inside T-3 minutes (the LH2 tank pressurization occurs about a minute later) and then have to scrub.
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#50
by
rdale
on 11 Dec, 2007 21:52
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We're still a ways away from the certified limit. Certainly makes more sense to tank the ET and use one of its many lives than make changes without 'real' conditions...
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#51
by
shuttlefan
on 12 Dec, 2007 12:40
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Will the Ice Inspection Team also go out to the pad and collect data about the ET's condition Tuesday, or is that not required for this test?
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#52
by
SimonShuttle
on 12 Dec, 2007 13:03
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shuttlefan - 12/12/2007 7:40 AM
Will the Ice Inspection Team also go out to the pad and collect data about the ET's condition Tuesday, or is that not required for this test?
Yeah, I think that's a given as cryo cycles = can affect foam.
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#53
by
rdale
on 12 Dec, 2007 13:58
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SimonShuttle - 12/12/2007 9:03 AM
Yeah, I think that's a given as cryo cycles = can affect foam.
I thought the ice team went out to check for ice that might fall off and damage the system during launch?
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#54
by
James (Lockheed)
on 12 Dec, 2007 16:22
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rdale - 12/12/2007 8:58 AM
SimonShuttle - 12/12/2007 9:03 AM
Yeah, I think that's a given as cryo cycles = can affect foam.
I thought the ice team went out to check for ice that might fall off and damage the system during launch?
Correct, though inclusive of all debris related hazards, such as cryo induced foam cracks etc. It is an operation based on an impending launch.
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#55
by
on 12 Dec, 2007 16:30
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Ok. Tell me why this isn't done for ECO sensors.
In radiology they use sealed liquid crystals at the end of optical fibres to gauge temperatures in treatment situations - sometimes in vivo.
If you used such, one could avoid various electronic/cryogenic issues. Such a system works in very hostile environments, as used in certain military testing with this same arrangement.
So whats the problem with using it in the ET? Please cure my stupidity on this issue.
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#56
by
zeke01
on 12 Dec, 2007 17:32
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Do they work in liquid H2 temperatures? Besides helium, everything else is frozen solid. Given the rate at which the tank is emptied, will these frozen crystals warm up enough in time to give the signal 'no longer immersed in H2' before the HPFTPs blow up? I don't think so.
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#57
by
on 12 Dec, 2007 18:40
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This isn't my area - but if we are talking enthalpy, that's not the stopper. They can respond in microseconds at cryogenic temperatures assuming the appropriate thin film.
If there were to be issues, my guess would be thermal shock/cycling and or change in properties of the fiber optics that make the sensors hard to read - e.g. you have to choose bandwidths between the absorption peaks.
I'm just wondering if the work has been done.
These things already work in far more hostile environments then a LH2 tank. I've seen them used at Berkeley and Batavia in supercooled LHe2 tanks far colder, and used with quantum level measurement. And they are used in even more unusual environments than described...
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#58
by
Mike_1179
on 12 Dec, 2007 20:08
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But the issue is likely not with the sensors, it's with the wiring and circuitry in the tank and the Point Sensor Box.
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#59
by
Chris Bergin
on 12 Dec, 2007 20:20
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Mike_1179 - 12/12/2007 9:08 PM
But the issue is likely not with the sensors, it's with the wiring and circuitry in the tank and the Point Sensor Box.
Correct, and given the absolute bulk of L2 documentation on the issue focuses on the LH2 feedthrough connector, that's the top candidate so far.
