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#380
by
DaveS
on 10 Aug, 2009 20:43
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oh ok do they need to be replaced then between firings?, seems like that could be a problem if theres an RSLS abort or something like that
They have to replaced if fired. I believe that was the main driver behind the 48 hr scrub turnaround between the first and second launch attempts of STS-93 in July 1999.
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#381
by
Jim
on 10 Aug, 2009 21:11
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oh ok do they need to be replaced then between firings?, seems like that could be a problem if theres an RSLS abort or something like that
Not a problem, there would be bigger issues to worry about like HPU/APU propellant and the reason for the RSLS abort. They would be replaced as a matter of course.
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#382
by
Hobbs
on 11 Aug, 2009 00:09
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are they mini solid motors with say iron/magnesium filings added, that kind of thing of something different?
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#383
by
DMeader
on 11 Aug, 2009 01:18
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Ive looked and had no luck googling this but what design are the ROFI sparklers that are used for the shuttle....
I've looked too, and found nothing. Would love to see some closeup photos of the actual hardware, not just while it is firing.
Can you imagine one, out in the middle of your yard, during a July 4th celebration?
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#384
by
Jim
on 11 Aug, 2009 01:22
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They are nothing but fountain sparklers. No big deal.
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#385
by
Lee Jay
on 11 Aug, 2009 01:36
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They are nothing but fountain sparklers. No big deal.
I'll bet NASA pays more than $4 a piece for them!
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#386
by
rdale
on 11 Aug, 2009 01:37
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#387
by
Lee Jay
on 11 Aug, 2009 01:49
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Ive looked and had no luck googling this but what design are the ROFI sparklers that are used for the shuttle....
I've looked too, and found nothing. Would love to see some closeup photos of the actual hardware, not just while it is firing.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890003237_1989003237.pdf has some info.
Nice quote:
"A ROFI is, in effect, a small rocket motor filled with zirconium pellets. These pellents [sic] flood the area between the SSME nozzles and the duct entrance with small (550-micron), extremely hot zirconium sparklers."
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#388
by
Hobbs
on 11 Aug, 2009 01:59
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Ahhh thanks for the link, good 'ol military style zirconium filings it seems, tbh with the way NASA does things I was half expecting these to have been like a multimillion dollar ATK contract with years of testing/evalutation and pages and pages of paperwork but apparently not:)
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#389
by
MKremer
on 11 Aug, 2009 19:28
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Are there any photos from UNDER the MLP while the stack is on the pad looking UP into the SRB nozzle? Shine a spotlight up into the booster core. I am presuming you could see the center hole all the way up to the top of the booster, right?
There are a few SRB test videos on L2 that show the ignition from the nozzle end, and some pics around the web (including from NASA and ATK) that show views into each segment, and segment mating views.
However, there's not much to see, except for a hole all the way up to the igniter cap. With really intense lights you might see the tips of the 1st segment star-shaped propellant mold sticking out, but it would still be a pretty boring view until ignition.
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#390
by
Hobbs
on 11 Aug, 2009 20:48
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ok just a few questions about the whole GLS shabang:
1. What type of computer is used to run the GLS software? is it located in the console or in a huge computer bank in a backroom somewhere
secondly, and bound to have been asked before but why is the GLS console behind a glass screen (I my have this wrong and its a different console but why are the two glass screens there atall?)
From what I understand the GLS operator has to manually "activate" the RSLS/Auto sequencer, is this just a case of pressing a button or is it more involved than that, same question goes about issuing a cutoff command,
Also is it true that this is the last time a human being has do something in order for the shuttle to put itself in orbit? (assuming everything works as planned)
Are there any pictures anywhere of the GLS console as this would really help answering some of these questions
thanks
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#391
by
Jim
on 11 Aug, 2009 21:11
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1. secondly, and bound to have been asked before but why is the GLS console behind a glass screen (I my have this wrong and its a different console but why are the two glass screens there atall?)
2. From what I understand the GLS operator has to manually "activate" the RSLS/Auto sequencer, is this just a case of pressing a button or is it more involved than that, same question goes about issuing a cutoff command,
3. Also is it true that this is the last time a human being has do something in order for the shuttle to put itself in orbit? (assuming everything works as planned)
1. What glass screen?
2. Computer entry.
3. The crew has to do some tasks.
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#392
by
HelixSpiral
on 11 Aug, 2009 21:11
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I believe the GLS is hands off after T-9, yes, but there are also cockpit switch throws the crew makes during terminal count without which the shuttle could not fly (e.g. connecting essential busses and starting APUs), so no, it's not really the last time a person has to take action.
Edit: Jim beat me.
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#393
by
Hobbs
on 11 Aug, 2009 21:29
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I would attach a picture however i cant find one to hand of firing room 4, but they are the two "greenhouse" type things at either corner of the room which seem to be sealed off from the rest of the room
Also what does the "computer entry" entail?
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#394
by
Jim
on 11 Aug, 2009 21:48
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I would attach a picture however i cant find one to hand of firing room 4, but they are the two "greenhouse" type things at either corner of the room which seem to be sealed off from the rest of the room
That is where the MMT and VIP's sit. The GLS is just a regular console
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#395
by
Variable
on 15 Aug, 2009 18:22
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How many successive scrubs can the system handle?
Are these driven by the ET fill/drain cycles (limited number?) or something else?
Is there a time constraint as well - as in the system can't stand on the pad for more than x-number of days? If so, what drives that? (not launch window related)
ty
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#396
by
Jorge
on 15 Aug, 2009 18:24
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How many successive scrubs can the system handle?
Are these driven by the ET fill/drain cycles (limited number?) or something else?
Is there a time constraint as well - as in the system can't stand on the pad for more than x-number of days? If so, what drives that? (not launch window related)
The cryo tanks for the fuel cells need to be topped off periodically due to boiloff. The exact frequency depends on mission-specific cryo margins but is typically once every 3-4 scrubs.
Limit on ET fill/drain cycles is 13.
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#397
by
Variable
on 15 Aug, 2009 18:33
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Ty Jorge.
More tank cycles than I had imagined. Is that number driven primarily by the foam? (my impression)
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#398
by
Jim
on 15 Aug, 2009 18:56
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How many successive scrubs can the system handle?
Are these driven by the ET fill/drain cycles (limited number?) or something else?
2 when the ET is filled for both launch crew rest and MPS inspections.
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#399
by
ChrisGebhardt
on 15 Aug, 2009 20:30
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To me a more important question is this: Why is the Russian program so inflexible regarding launch dates?
It seems to me that Soyuz or Progress launches are set in stone by GOD and Shuttle with all of its weather related and other challenges always has to stand down to let Soyuz or Progress "play thru". Why can't Progress or Soyuz slip their launch a few days to let Shuttle "play thru"?
Heck, we even seriously contemplate shortening Shuttle missions so they can undock in time for a Progress or Soyuz launch. Why does this make sense? Slip the Russian launch a couple of days and we don't have to do this.
What am I missing here?
Well, for one thing the Shuttle launch pads are only used to launch Space Shuttles. Russia conducts many more missions per year than we do here in the U.S. and the launch pads that launch the Progress and Soyuz vehicles are also used to launch other vehicles. It's all about maintaining schedules and seeing what you can slip this way and delete here.
When we cut content from STS-119 (which I'm fairly certain is the first time we've ever lopped content off an ISS mission just to get it launched in a given window), it was because those activities that were cut could easily be performed by the Station crew after the Shuttle left. They were just a part of the original mission because SSPTS allows us to stayed docked longer and it was slightly more convenient to have them done when the shuttle was there.
STS-119 lost nothing because we took an EVA off to get the mission up before Soyuz (and by doing that we were able to preserve STS-125 in May and the opening launch attempt for STS-127 in June).
And Soyuz and Progress have slipped for Shuttle before when we've needed them to. STS-115 is great example of that. However, the simple fact is, Shuttle is more flexible than Soyuz and Progress which have constraints as to how long they can be on orbit for (Soyuz) and constraints as to how far their launches can slip because they are bringing needed food, water, and supplies to the Station crew (Progress and Soyuz).
