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#1020
by
Jorge
on 18 Sep, 2007 14:07
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C5C6 - 18/9/2007 8:59 AM
just wanted to ask......in cases like STS-120, you can see that the payload bay is not completely occupied........why don't they occupy it with a smaller payload for the iss, or an independent sattelite/experiment......looks like they were wasting payload capability......
It is completely occupied, regardless of what it looks like. Payload is typically constrained by mass and c.g. location, not volume.
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#1021
by
TJL
on 19 Sep, 2007 01:43
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STS-120 has a two different flight directors for launch and entry.
Is this the first time a single director isn't used for both events?
Thank you.
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#1022
by
psloss
on 19 Sep, 2007 10:42
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TJL - 18/9/2007 9:43 PM
STS-120 has a two different flight directors for launch and entry.
Is this the first time a single director isn't used for both events?
No, they just did that on STS-116 with Norm Knight. Given that this will be Bryan Lunney's first shift as Entry FD, I'm assuming it's the same thing, too -- Steve Stich was promoted and Lunney has moved into the Ascent/Entry FD role.
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#1023
by
shuttlefan
on 19 Sep, 2007 13:26
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When Enterprise was on SLC-6 at Vandenberg in 1985, did the 62-A crew actually do any training on the pad down there?
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#1024
by
brahmanknight
on 20 Sep, 2007 15:37
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Why are there built in holds in the shuttle, and other rocket's, countdown?
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#1025
by
Jim
on 20 Sep, 2007 16:32
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brahmanknight - 20/9/2007 11:37 AM
Why are there built in holds in the shuttle, and other rocket's, countdown?
Shuttle does things just a little different from ELV's. The "countdown" is always 43 hours. The holds are lengthened and shortened to accomodate differences in the missions (payload). The holds are always in the same place in the countdown. What controls what happens in the holds is the S0007 schedule.
ELV always use the same countdown and the holds don't change (. Their countdowns are also shorter (tens of hours shorter). The procedures before the countdown (coutntdown preps) take care of differences
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#1026
by
Thorny
on 20 Sep, 2007 17:46
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pad rat - 20/9/2007 11:13 AM
It allows time to catch up on tasks that may have fallen behind a bit on the schedule, as well as time to deal with issues that may have arisen during the count.
But technically, why does the countdown clock have to stop? Instead of a 43 hour countdown that takes 70-odd hours with built-in holds, why don't they just use a 70-hour countdown with no holds?
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#1027
by
Jim
on 20 Sep, 2007 18:17
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Thorny - 20/9/2007 1:46 PM
pad rat - 20/9/2007 11:13 AM
It allows time to catch up on tasks that may have fallen behind a bit on the schedule, as well as time to deal with issues that may have arisen during the count.
But technically, why does the countdown clock have to stop? Instead of a 43 hour countdown that takes 70-odd hours with built-in holds, why don't they just use a 70-hour countdown with no holds?
Like I said the holds times increase and decrease and like pad rat said the holds are to make up work. The actual countdown procedure is tied to specific T- times. This would entail a rewrite of the procedure for each mission. Launch is not at the same amount of time from the beginning of the count
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#1028
by
GLS
on 20 Sep, 2007 18:17
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Thorny - 20/9/2007 6:46 PM
pad rat - 20/9/2007 11:13 AM
It allows time to catch up on tasks that may have fallen behind a bit on the schedule, as well as time to deal with issues that may have arisen during the count.
But technically, why does the countdown clock have to stop? Instead of a 43 hour countdown that takes 70-odd hours with built-in holds, why don't they just use a 70-hour countdown with no holds?
During BIHs there's not much to do, and so the BIHs act like a overrun when major activities are delayed. It's like a buffer zone.
The clock stops because it's easier, you start the countdown at the top of the hour, the BIHs start/end at *round* times and you just have to think minutes and seconds in the end of the countdown.
It's just better.
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#1029
by
Ender0319
on 20 Sep, 2007 22:02
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Oh but they do rewrite the S0007 (and S0017) procedure for every mission. People submit redlines, they reprinte the volumes of the books, kill trees, destroy ink supplies, etc. It's crazy but they do it. So I think it would be feasible to have a much longer countdown without holds but I think you've made the correct arguments as to why there are holds in the countdown.
Besides... Shuttle has always done it this way with holds...
Jim - 20/9/2007 1:17 PM
Like I said the holds times increase and decrease and like pad rat said the holds are to make up work. The actual countdown procedure is tied to specific T- times. This would entail a rewrite of the procedure for each mission. Launch is not at the same amount of time from the beginning of the count
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#1030
by
mkirk
on 20 Sep, 2007 23:34
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Ender0319 - 20/9/2007 5:02 PM
Oh but they do rewrite the S0007 (and S0017) procedure for every mission. People submit redlines, they reprinte the volumes of the books, kill trees, destroy ink supplies, etc. It's crazy but they do it. So I think it would be feasible to have a much longer countdown without holds but I think you've made the correct arguments as to why there are holds in the countdown.
Besides... Shuttle has always done it this way with holds...
Jim - 20/9/2007 1:17 PM
Like I said the holds times increase and decrease and like pad rat said the holds are to make up work. The actual countdown procedure is tied to specific T- times. This would entail a rewrite of the procedure for each mission. Launch is not at the same amount of time from the beginning of the count
Built in holds (BIH) have been around since long before the Shuttle. With regard to the manned vehicles BIHs were of particular importance during Gemini because they were running parallel countdowns (one for the Atlas Agena rendezvous target vehicle and another for the Gemini Titan) and they were dealing with small launch windows.
Shuttle Countdowns are far more integrated than previous vehicles like Apollo – meaning that a single controlling document runs all of the test operations. During Apollo you had parallel countdowns for the Booster, Spacecraft, and LM with everyone synching up during the last few minutes of the count.
I should also point out that it took a long time to “standardize” and streamline the current shuttle countdown. For example the countdown for STS-1 started at T-73 hours and had 30 hours and 20 minutes of built in hold time. That made the total countdown over 103 hours long. Tasks, such as GN2 and Helium pressurization of the OMS/RCS, that are currently done “pre-count” now, were done within the S0007 structure for the first few shuttle flights.
STS-6 had a 96 hour countdown with 26.5 hours of built in hold time added to that. I believe STS-8 was the first countdown to get into the 40 hour range. It took another few years and several more flights (well past the first return to flight era) before the current 43 hour countdown was formulated.
As time went on the launch teams were able to reduce the times needed for many tasks, reduce the number of test requirements, and improve task, hardware, and process efficiency.
ENDER0319 is right about the dead trees. I was always amazed at how many trees have given their lives for the good of the program. Every single flow the S0007 gets revised. There were times when we were less than a week away from call to stations – I already had one dead tree in my countdown notebook (i.e. about a thousand pages per volume with S0007 consisting of 5 volumes back then – it is now 6) and sure enough a brand new revision would come out which made my previous dead tree completely useless. At least the world of adobe PDF has saved one or two trees compared to how things used to be.
Currently the basic space shuttle countdown structure is always the same, meaning the holds are always in the same places, but the sequencing gets adjusted and the hold durations are changed based on mission and payload requirements.
The idea and philosophy is to standardize as much of the process as possible in an environment where things are always changing.
Mark Kirkman
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#1031
by
brahmanknight
on 21 Sep, 2007 18:22
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Does anyone have photos or a discription of the Stabailized Payload Deployment System? I have read it was involved in the Sts 33R DOD mission.
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#1032
by
MKremer
on 21 Sep, 2007 18:53
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Could either be a DoD 'alternative' description for one of the deployment types used for the many Shuttle commercial sat deployments, or is a special classified (or ITAR'd) deployment system.
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#1033
by
Jim
on 21 Sep, 2007 19:07
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It wasn't on STS-33 and there aren't any photos
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#1034
by
jeff122670
on 23 Sep, 2007 00:41
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I noticed that on the 41-D FRF as well as the launch right at about T-15 seconds, the water system seems a bit different. As the water activates, it appears as though there is a "fan" of water that sprays UP from underneath the MLP. This fan of water starts first and then all of the other water starts dumping down.
I haven't noticed it on any other launches and at that time the only pad being used was 39-A, so I dont think it is pad specific, but it certainly is "interesting" looking especially since I havent seen it on any other launches.
Does anyone know if it is simply a function of the water flowing through the pipes at differernt speeds (ie, this always happens, but we never see it because it is masked by the falling water) or was this a change to the water system.
Thanks!!
Jeff
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#1035
by
GLS
on 23 Sep, 2007 10:58
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jeff122670 - 23/9/2007 1:41 AM
I noticed that on the 41-D FRF as well as the launch right at about T-15 seconds, the water system seems a bit different. As the water activates, it appears as though there is a "fan" of water that sprays UP from underneath the MLP. This fan of water starts first and then all of the other water starts dumping down.
I haven't noticed it on any other launches and at that time the only pad being used was 39-A, so I dont think it is pad specific, but it certainly is "interesting" looking especially since I havent seen it on any other launches.
Does anyone know if it is simply a function of the water flowing through the pipes at differernt speeds (ie, this always happens, but we never see it because it is masked by the falling water) or was this a change to the water system.
Thanks!!
Jeff
On the North side of the flame trench there's 2 pipes that inject water into the flame trench and part of that water is routed up to the MLP, by pipes on the 2 SRB flame deflectors (I think that's the correct name...), to the pipes around the SRB flame hole, and the water is then injected just below the SRB nozzle to supress the shock wave generated at ignition. Those SRB flame deflectors move on tracks from the "parking" position, just to the North of the MLP, to the launch position, below the MLP, with their pipes connecting the pipes on the trech to the pipes on the MLP.
On the FRF these flame deflectors aren't needed (no SRB firing), so the connections on the flame trench pipes are not used, so probably they are covered. The "fan like spray" is probably water leaking from that cover.
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#1036
by
jeff122670
on 24 Sep, 2007 00:10
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does anyone know the story with the STS-1 GOX vent arm. i noticed it wasnt used during the final count of STS-1 and then with STS-2, the vent piping system was changed to what we see now. i have some video somewhere that showed STS-1 at night on the pad with the vent arm being retracted and LOX venting from the tip of the external tank. was there a problem with the arm or beenie cap?
ALSO, within the last several years, i have noticed that the actual beenie cap now has what APPEAR to be "whiskers" sticking out from the perimeter of the cap. looks like a lightning protection system, but not sure. they appear to run circumferentially (spell?) around the cap.
thanks for the help!
Jeff
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#1037
by
Jim
on 24 Sep, 2007 00:19
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The system wasn't working for STS-1 and was moved out of the way.
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#1038
by
parham55
on 24 Sep, 2007 01:14
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Any close up pictures of the sling attatchment points on the orbiters? Thanks.
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#1039
by
Lee Jay
on 24 Sep, 2007 01:24
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parham55 - 23/9/2007 7:14 PM
Any close up pictures of the sling attatchment points on the orbiters? Thanks.
Do a search here:
http://mediaarchive.ksc.nasa.gov/for "sts-117 mate demate".
When it was up on the mate/demate device at KSC, they got some tight pictures.
