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#820
by
Jim
on 25 Mar, 2008 16:39
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Firestarter - 25/3/2008 1:34 PM
http://www.nasaspaceflight.com/content/?cid=5388 Chris writes about something called CSCS and explains it well, but what happens if LON was called, the shuttle crew stay on the ISS and wait for another shuttle, but in the meantime, something goes badly wrong with the ISS. How do they evacute with only one Soyuz?
That is a risk. But it means two bad things have happened, so it is very unlikely
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#821
by
Bret
on 25 Mar, 2008 17:28
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Random VAB question that has been gnawing at me ... the crane that lifts the shuttle vertical and over the transfer aisle for mating with the stack must be *uber-reliable* to be trusted to lift such an irreplaceable asset. Is there some sort of back-up or safety cable if the main cable breaks or slips?
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#822
by
Jim
on 25 Mar, 2008 17:33
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Bret - 25/3/2008 2:28 PM
Random VAB question that has been gnawing at me ... the crane that lifts the shuttle vertical and over the transfer aisle for mating with the stack must be *uber-reliable* to be trusted to lift such an irreplaceable asset. Is there some sort of back-up or safety cable if the main cable breaks or slips?
nope. The orbiter is no different than any other high dollar lift done around the world.
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#823
by
Lee Jay
on 25 Mar, 2008 17:33
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I don't have specifics on the 325 ton crane in the VAB, but in general cranes and their cables are reliable because they are maintained, inspected, and tested quite often. Testing usually involves overloading (something like 125%) and components are often designed to fail at around 4x of rated load. So, let's say it's tested to 1.25x325 tons = 812,500 pounds and it has around a 3x ultimate safety factor on that. Now it has to lift an empty orbiter that weighs something like 125,000 pounds. The safety factor on failure of that lift is extremely large - something like 20.
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#824
by
JWag
on 25 Mar, 2008 17:45
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Lee Jay - 23/3/2008 3:18 PM
What are we seeing in this image that makes the SSMEs look as if they're "glowing"? I realize it's probably sunlight reflecting off of something deep inside. Combustion chamber? What material is it made of that makes it seem so shiny?
http://spaceflight1.nasa.gov/gallery/images/shuttle/sts-123/hires/iss016e032429.jpg
That's a spectactular picture.
I thought I had read that the main injector was machined from copper, but after
Googling I found
this:
Nickel is electroformed onto the copper material of the thrust chamber to provide the required combination of strength and heat transfer characteristics.
Which is pretty much what Jim said.
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#825
by
elmarko
on 25 Mar, 2008 21:57
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Here's a nice simple question for you that someone asked me today and I promised him I'd ask for him.
Why are OPS 5 and OPS 7 not used on the GPCs? Were they reserved for other things and then not used? Or is there another reason why no software exists under those numbers?
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#826
by
Namechange User
on 25 Mar, 2008 22:38
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Lee Jay - 25/3/2008 1:33 PM
I don't have specifics on the 325 ton crane in the VAB, but in general cranes and their cables are reliable because they are maintained, inspected, and tested quite often. Testing usually involves overloading (something like 125%) and components are often designed to fail at around 4x of rated load. So, let's say it's tested to 1.25x325 tons = 812,500 pounds and it has around a 3x ultimate safety factor on that. Now it has to lift an empty orbiter that weighs something like 125,000 pounds. The safety factor on failure of that lift is extremely large - something like 20.
There is a large "proof load" sphere in the VAB that is used to make sure the crane continues to be up to task as well.
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#827
by
Lee Jay
on 25 Mar, 2008 22:52
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OV-106 - 25/3/2008 5:38 PM
Lee Jay - 25/3/2008 1:33 PM
I don't have specifics on the 325 ton crane in the VAB, but in general cranes and their cables are reliable because they are maintained, inspected, and tested quite often. Testing usually involves overloading (something like 125%) and components are often designed to fail at around 4x of rated load. So, let's say it's tested to 1.25x325 tons = 812,500 pounds and it has around a 3x ultimate safety factor on that. Now it has to lift an empty orbiter that weighs something like 125,000 pounds. The safety factor on failure of that lift is extremely large - something like 20.
There is a large "proof load" sphere in the VAB that is used to make sure the crane continues to be up to task as well.
Do you know what it weighs? The term "proof load" indicates it's probably 90%-100% of rating, not the test-load of 125% of rating.
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#828
by
Jim
on 25 Mar, 2008 23:38
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Lee Jay - 25/3/2008 7:52 PM
OV-106 - 25/3/2008 5:38 PM
Lee Jay - 25/3/2008 1:33 PM
I don't have specifics on the 325 ton crane in the VAB, but in general cranes and their cables are reliable because they are maintained, inspected, and tested quite often. Testing usually involves overloading (something like 125%) and components are often designed to fail at around 4x of rated load. So, let's say it's tested to 1.25x325 tons = 812,500 pounds and it has around a 3x ultimate safety factor on that. Now it has to lift an empty orbiter that weighs something like 125,000 pounds. The safety factor on failure of that lift is extremely large - something like 20.
There is a large "proof load" sphere in the VAB that is used to make sure the crane continues to be up to task as well.
Do you know what it weighs? The term "proof load" indicates it's probably 90%-100% of rating, not the test-load of 125% of rating.
proofload is more than operational load - 125 to 150%
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#829
by
nathan.moeller
on 26 Mar, 2008 17:39
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Though it's highly improbable that this would ever happen, what would happen in the event of one, or both, SRBs failing to separate from the stack at the end of first stage?
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#830
by
brahmanknight
on 26 Mar, 2008 19:44
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I've been told that the stack would start to lose stability and breakup. LOC.
Wait. I thought you said if one didn't separate. I assume if both didn't separate, the dead weight on the ET would be too stressful and would structurally fail.
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#831
by
gordo
on 26 Mar, 2008 22:49
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Fortunately after SRB burn out the shuttle would be in an intact abort mode, well at least an abort mode where they could get off the Tank and look into bailing out.
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#832
by
nathan.moeller
on 27 Mar, 2008 18:48
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gordo - 26/3/2008 6:49 PM
Fortunately after SRB burn out the shuttle would be in an intact abort mode, well at least an abort mode where they could get off the Tank and look into bailing out.
That's my thinking. I'm just wondering what they would do to abort the launch.
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#833
by
jeff122670
on 27 Mar, 2008 19:41
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GLS go for Auto Sequence Start...................does it occur at T-31 or T-27? i have heard both..... i am assuming it is commanded at -31 and actually completes at -27.......
can anyone answer?
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#834
by
Jim
on 27 Mar, 2008 19:47
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jeff122670 - 27/3/2008 4:41 PM
GLS go for Auto Sequence Start...................does it occur at T-31 or T-27? i have heard both..... i am assuming it is commanded at -31 and actually completes at -27.......
can anyone answer?
The auto sequence starts at 31 and ends at zero. "GLS go for Auto Sequence Start" is just saying the system is ready.
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#835
by
psloss
on 27 Mar, 2008 21:14
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jeff122670 - 27/3/2008 4:41 PM
GLS go for Auto Sequence Start...................does it occur at T-31 or T-27? i have heard both..... i am assuming it is commanded at -31 and actually completes at -27.......
I believe it was T-27 for the first launch only. The way I recall it (and fortunately my mistakes will be corrected here), many things changed based on the results of the first launch campaign (and the first flight, obviously). For the first launch count (and the FRF before it), that GLS milestone was at T-27 and liftoff during launch count was approx. four seconds after T-0. By the time STS-2 occurred, those two aspects of the count were changed.
But we only get one first impression and sometime in that period a reference or a newspaper story or some combination of those extrapolated from that one launch to assume that "if it happens this way once, it happens this way every time."
Another example of the changes that were going on based on experiences during and after the first launch campaign: the video of the FRF before STS-1 shows the hydrogen burn igniters starting closer to main engine start than in countdowns today. Perhaps based on what was learned post-firing the sequence was changed, because by the time of the launch the igniters started earlier in the sequence -- roughly with the GLS "go for main engine start." (As occurs today.)
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#836
by
Susan27
on 27 Mar, 2008 22:59
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Hi,
when viewing STS-123 rolling out yesterday night at SLF I noticed the APU-venting as a yellow coloured flash/steam (like a lava-lamp). The narrator said that this would be absolutely normal and the same as on daylight landings...
Question: When watching daytime landings vids I see those "steam" coming out from the APU but the colour is something "grey" but really NOT so extreme bright yellow/orange. Could you explain why on night landings the colour of the steam is like that or does that orange colour have to do with the special lenses NASA uses when TV-recording night landings...?
Thanks in advance!
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#837
by
jeff122670
on 27 Mar, 2008 23:02
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i read a thread once on here about the GLS......if anyone has that link, can you please repost...
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#838
by
Susan27
on 27 Mar, 2008 23:53
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I am watching this vid of STS-123 reentry:
At exactly
2:28 min. the big screen at the very right (front) of Mission-Control-Room is shown with two graphics. What do that graphics mean? Are these parts of the ideal reentry corridor after Entry-Interface or what do those lines exactly mean...?
Thanks very much!
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#839
by
cabbage
on 27 Mar, 2008 23:58
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nathan.moeller - 27/3/2008 8:48 PM
gordo - 26/3/2008 6:49 PM
Fortunately after SRB burn out the shuttle would be in an intact abort mode, well at least an abort mode where they could get off the Tank and look into bailing out.
That's my thinking. I'm just wondering what they would do to abort the launch.
From my amateur reading of the Ascent/Aborts FPH, 3 E/O in first stage inhibits SRB sep during thrust tailoff - so if they commanded MECO after failure to separate they'd end up in that abort zone.
However, assuming that they have largely cleared the atmosphere and there would be little drag from the SRBs could they not continue in powered flight for TAL (assuming they could successfully command ET SEP)? Is the deadweight of the SRBs a structural concern or a control issue?
