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#20
by
Halidon
on 04 Dec, 2014 10:51
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Fouled range? What the heck? Another sailboat?
Boat of some sort they are saying.
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#21
by
stewart
on 04 Dec, 2014 10:57
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Why did they change to Com 1? What was all that about?
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#22
by
mcgyver
on 04 Dec, 2014 11:05
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What is the fire visible down-left in images?
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#23
by
Mark McCombs
on 04 Dec, 2014 11:08
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What is the fire visible down-left in images?
Hydrogen flare.
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#24
by
Norm38
on 04 Dec, 2014 11:09
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^^^ The red flame? Hydrogen being flared off.
Why doesn't NASA TV have a countdown clock? Got up to shower, couldn't get any audio on my phone, and no clock, didn't know they were on hold till just now.
Edit: Nevermind. They put the clock back up, then took it back down as soon as they announced the Hold due to winds. They must have been in a hold the whole time I was watching earlier.
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#25
by
mcgyver
on 04 Dec, 2014 11:19
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What is the fire visible down-left in images?
Hydrogen flare.
Why?!?
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#26
by
Jim
on 04 Dec, 2014 11:20
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What is the fire visible down-left in images?
Hydrogen flare.
Why?!?
Liquid hydrogen is boiling off in the vehicle and needs to be disposed of.
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#27
by
Norm38
on 04 Dec, 2014 11:23
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Does anyone know how the Delta IV-H wind limits compare to other vehicles. Don't recall the F9 ever having to hold due to wind. But it's a much smaller vehicle.
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#28
by
rdale
on 04 Dec, 2014 11:29
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It's proprietary. Makes forecasting more difficult
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#29
by
enkarha
on 04 Dec, 2014 11:42
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According to NTV just now, it's 21 knots.
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#30
by
rdale
on 04 Dec, 2014 11:48
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Not sure that was supposed to slip out
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#31
by
Bargemanos
on 04 Dec, 2014 11:51
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Why would such thing be a "secret"? Its just a wind speed..
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#32
by
mcgyver
on 04 Dec, 2014 12:27
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I think I see two cameras close one to the other in the TV stream.
Was any launch ever streamed in 3d? That would be amazing!
Is anybody aware of available streams (or recordings, in next hours) from quite-similar points of view? I'll try to create a 3d footage.
What does "Fuel and drain valve did not close" mean?
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#33
by
Nanimo
on 04 Dec, 2014 12:30
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Not sure that was supposed to slip out
Might not be the "usual" wind limit for a DIV-H launch
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#34
by
SkipMorrow
on 04 Dec, 2014 12:45
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Fuel and drain vales. I am wondering where they are in the schematic. I imagine a large pressurized liquid hydrogen/oxygen tank inside the rocket, with a valve sticking out the side. They connect the fuel line to this valve when it is time to fill the rocket up, or to drain it. Since the tank is pressurized, if the valve doesn't shut, then the fuel will all leak out. Why would they need to shut this valve so late in the countdown? Isn't the valve closed when they are done filling the tank?
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#35
by
Mark McCombs
on 04 Dec, 2014 12:52
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Why would they need to shut this valve so late in the countdown? Isn't the valve closed when they are done filling the tank?
As the propellants boil off there is a need to "top off the tanks" prior to launch.
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#36
by
mheney
on 04 Dec, 2014 12:53
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"Fill and Drain". These are at the bottom of the tanks (you can't drain from the top ....), and because of the nature of the fuel/oxiders (cryogenic), they need to top off (replenish) to make up for boil-off. So the valves are open until shortly before launch; near the end of the count, you ensure that you're as full as you need to be, then close the valves, then, in short oder, you go.
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#37
by
mcgyver
on 04 Dec, 2014 12:59
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Are the countdown steps of Delta-IV (or any other rocket) public? (at least for last 10-20 minutes)
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#38
by
LouScheffer
on 04 Dec, 2014 13:08
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Problems with port and core valve cycling. LOX valves are OK. The problems are with the LH2 valves.
'Sticky' valves from a long pre-launch cold soak?
Concur.
So is the valve not working to spec? Or the spec does not require the valve to work after a long hold? Either one seems odd to me - long holds are hardly an unusual occurance, so it should be covered by the spec. And on the valve side, surely some acceptance test requires it to work after a long cold soak.
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#39
by
Hog
on 04 Dec, 2014 13:12
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Are the countdown steps of Delta-IV (or any other rocket) public? (at least for last 10-20 minutes)
This mission for Delta IV-Heavy is on L2.
