-
#440
by
Danny Dot
on 25 Aug, 2009 07:43
-
Is this what you're looking for?
9:41 pm Countdown resumes at the T-3 hour mark
12:21 am Countdown enters a 10-minute hold at the T-20 minute mark
12:31 am Countdown resumes at the T-20 minute mark
12:42 am Countdown enters an ~45-min. hold at the T-9 minute mark
1:27:05 am Countdown resumes at the T-9 minute mark
Yes, thank you. 10 minute hold at T minus 20, 45 minutes at T-9. How about the T minus 3 hour hold? How long is it?
Danny
-
#441
by
AnalogMan
on 25 Aug, 2009 07:47
-
Is this what you're looking for?
9:41 pm Countdown resumes at the T-3 hour mark
12:21 am Countdown enters a 10-minute hold at the T-20 minute mark
12:31 am Countdown resumes at the T-20 minute mark
12:42 am Countdown enters an ~45-min. hold at the T-9 minute mark
1:27:05 am Countdown resumes at the T-9 minute mark
Yes, thank you. 10 minute hold at T minus 20, 45 minutes at T-9. How about the T minus 3 hour hold? How long is it?
Danny
2hr 30mins hold at T minus 3 hours.
2hr hold at T minus 6 hours (normally)
Edit: 1 hour hold at T minus 6 hours for this STS-128 24-hour scrub
-
#442
by
Hobbs
on 25 Aug, 2009 17:34
-
During tanking/replenish is the LO2 pumped through the SSMEs and then into the tank or is it sent straight up into the tank with a "trickle" sent through the engines, if its option 2 what percentage of the total flow is sent to the engines?
-
#443
by
ChrisGebhardt
on 25 Aug, 2009 20:08
-
LH2 and LOX are loaded through the T0 umbilicals into the aft of the Orbiter, then up through the porpellant lines and into the respective tanks of the ET.
-
#444
by
mkirk
on 25 Aug, 2009 20:33
-
During tanking/replenish is the LO2 pumped through the SSMEs and then into the tank or is it sent straight up into the tank with a "trickle" sent through the engines, if its option 2 what percentage of the total flow is sent to the engines?
As the oxygen comes in from the Tail Service Mast via the Fill & Drain Lines, it flows into the common LO2 Manifold (that all 3 engines feed from) and through the prevalves and into the engines - while it can flow through the turbo pumps it CAN NOT flow into the cumbustion chamber because the main oxidizer valves are closed at this point. From the LO2 Manifold the flow of oxygen also goes out through the ET Feedline Disconnect and up the Downcomer (this is the 17 inch feedline you see running up the outside of the ET) and into the bottom of the oxygen portion of the external tank.
Mark Kirkman
-
#445
by
ceepdublu
on 26 Aug, 2009 03:45
-
What does the scrub scenario look like if one of the LH2 fill/drain valves were to get stuck in the closed position? Wait a week for boiloff via flarestack?
-
#446
by
ChrisGebhardt
on 26 Aug, 2009 03:54
-
They said in the presser that they can drain the tank through the PV13 valve... it would just take hours long than usual.
-
#447
by
butters
on 26 Aug, 2009 04:24
-
If the fill/drain valve issue is an instrumentation problem, what instrumentation would be involved? Is there any instrumentation within the valve assembly that indicates position, or is valve position derived from pressure transducers in the feedline manifold, external tank, tail service mast, etc.?
Seems to me that if they know the pressures in the LH2 tank and T-0 umbilical, then they should be able to determine the position of the fill/drain valve unless there is an off-nominal leak in the circuit. So if there's a problem with the valve instrumentation itself (if applicable) or the feedline manifold pressure transducer, then there should be alternative methods of monitoring the valve position.
-
#448
by
brahmanknight
on 26 Aug, 2009 11:19
-
Is there a list of the all the Criticality 1 systesms on the space shuttle?
-
#449
by
Jim
on 26 Aug, 2009 11:23
-
then there should be alternative methods of monitoring the valve position.
Not viable. How would position be know with no flow?
-
#450
by
joncz
on 26 Aug, 2009 15:00
-
What does the scrub scenario look like if one of the LH2 fill/drain valves were to get stuck in the closed position? Wait a week for boiloff via flarestack?
There's an 8-1/2 minute rapid-drain procedure - but it's likely a one-shot deal
-
#451
by
ceepdublu
on 26 Aug, 2009 15:38
-
There's an 8-1/2 minute rapid-drain procedure - but it's likely a one-shot deal
[/quote]
That was actually my initial thought before asking the question...
-
#452
by
cabbage
on 26 Aug, 2009 21:17
-
I notice on another thread that after boiloff they have inerted the tank with helium. Is there a reason for using helium for this rather than (say) nitrogen? Is it a concern that the tank is too cold for nitrogen?
-
#453
by
Jim
on 26 Aug, 2009 21:21
-
I notice on another thread that after boiloff they have inerted the tank with helium. Is there a reason for using helium for this rather than (say) nitrogen? Is it a concern that the tank is too cold for nitrogen?
LH2 would condense the N2
-
#454
by
ginahoy
on 27 Aug, 2009 02:11
-
My apologies if this has been asked before...
After a 24-hr weather scrub, I'm trying to understand the specific reasons why the vehicle can't remain fueled and then topped off prior to crew arrival the following day. Is it due to the volatility of the liquid hydrogen? Or would it waste too much fuel via boil-off? Or would the ET turn into a huge icicle due as the insulation and tank mass loses all its embodied heat? Are there other factors?
-
#455
by
Jim
on 27 Aug, 2009 04:35
-
Is it due to the volatility of the liquid hydrogen? Or would it waste too much fuel via boil-off?
Bingo
-
#456
by
glen4cindy
on 27 Aug, 2009 04:39
-
What does the scrub scenario look like if one of the LH2 fill/drain valves were to get stuck in the closed position? Wait a week for boiloff via flarestack?
There's an 8-1/2 minute rapid-drain procedure - but it's likely a one-shot deal
This "8-1/2 minute rapid drain sounds like a "launch" without lighting the SRB's. But, that is not even a consideration right? Wouldn't that require replacement of the SSME's?
-
#457
by
glen4cindy
on 27 Aug, 2009 04:42
-
LH2 and LOX are loaded through the T0 umbilicals into the aft of the Orbiter, then up through the porpellant lines and into the respective tanks of the ET.
Are the T0 umbilicals those grey things that stand up from the MLP behind the wings?
If not, where are they located?
Thanks.
-
#458
by
Jim
on 27 Aug, 2009 04:45
-
LH2 and LOX are loaded through the T0 umbilicals into the aft of the Orbiter, then up through the porpellant lines and into the respective tanks of the ET.
Are the T0 umbilicals those grey things that stand up from the MLP behind the wings?
If not, where are they located?
Those are the tail service masts, in which the T-0 umbilicals are located
-
#459
by
ChrisGebhardt
on 27 Aug, 2009 05:00
-
What does the scrub scenario look like if one of the LH2 fill/drain valves were to get stuck in the closed position? Wait a week for boiloff via flarestack?
There's an 8-1/2 minute rapid-drain procedure - but it's likely a one-shot deal
This "8-1/2 minute rapid drain sounds like a "launch" without lighting the SRB's. But, that is not even a consideration right? Wouldn't that require replacement of the SSME's?
He was being facetious.
