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#60
by
Jim
on 02 Feb, 2007 11:47
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They were planning 109% for the Shuttle Centaur missions
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#61
by
mkirk
on 02 Feb, 2007 15:27
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pad rat - 2/2/2007 8:40 AM
Isn't the "old" 109% today's 104% due to pump upgrades?
There has been a lot of work done to certify higher thrust levels to help gain some performance and to close black zones (points in the ascent trajectory where certain abort options are not expected to be survivable). 106, 109 and even 115 have all had serious attention – depending I guess on how you define serious.
106 was kind of going to be the new 104.5 but much of the certification work and testing was halted after Columbia. There were initial concerns about 106 for use in first stage with regard to excessive loading - I believe that had been mostly worked out.
When Parsons was still the Shuttle Program Manager I asked him about the SSME power settings and he said it just didn’t make sense for the program to spend the money given the reduced manifest and the fact that the remaining flights didn’t need the additional performance.
There were some changes in the flight software (around OI-26 or 27 I believe) that would have allowed the 106 setting in place of 104.5 for “performance critical” missions.
Mark Kirkman
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#62
by
gordo
on 02 Feb, 2007 20:18
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Is there a contigency thrust level avail for abort situations?
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#63
by
mkirk
on 02 Feb, 2007 21:13
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gordo - 2/2/2007 3:18 PM
Is there a contigency thrust level avail for abort situations?
Yes MAX THROTTLES are available for thrust deficient abort scenarios. The crew types in an "ITEM 4" into the SPEC 51 OVERRIDE display for the GPCs (General purpose computers) and that changes the maximum throttle setting from 104.5% to 109%. This also applys for manual throttling, if the Pilot (left seater) pushes the lever full forward it will now be set for 109%.
The risk of using the higher uncertified power level is outweighed by the risks of not completing the abort successfully.
Mark Kirkman
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#64
by
nathan.moeller
on 02 Feb, 2007 21:19
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#65
by
stefan1138
on 02 Feb, 2007 23:26
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I hope this has not been discussed before. Following I post a direct view of OV-103. I have marked the odd tile(s) directly under the pilot´s window. This seems to be there since Discovery came out of Palmdale in 1983. Why is it there? Is there something underneath which needs special protection?
Stefan
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#66
by
Jim
on 02 Feb, 2007 23:26
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There is a shuttle Q&A thread
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#67
by
stefan1138
on 02 Feb, 2007 23:26
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Unfortunately did not find this in the Q&A and thought the Discovery section would be suitable for this question (because this tile pattern is only found on Discovery).
Stefan
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#68
by
nathan.moeller
on 03 Feb, 2007 01:20
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Wow that's strange. I've never noticed that before. Flightstar might know. He works pretty close with the orbiters if I'm not mistaken
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#69
by
MKremer
on 03 Feb, 2007 03:23
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#70
by
Flightstar
on 03 Feb, 2007 03:56
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nathan.moeller - 2/2/2007 8:20 PM
Wow that's strange. I've never noticed that before. Flightstar might know. He works pretty close with the orbiters if I'm not mistaken
I'm aft electrical.
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#71
by
nathan.moeller
on 03 Feb, 2007 18:59
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Okay. My bad Flightstar. Still a pretty awesome job
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#72
by
kanathan
on 03 Feb, 2007 20:30
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I know that the shuttle crews train extensively for the normal abort modes that they might encounter, such as RTLS or ATO, but do they do any training for the contingency aborts such as "fast sep"?
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#73
by
nathan.moeller
on 03 Feb, 2007 21:04
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kanathan - 3/2/2007 3:30 PM
I know that the shuttle crews train extensively for the normal abort modes that they might encounter, such as RTLS or ATO, but do they do any training for the contingency aborts such as "fast sep"?
I don't believe there is any fast separation abort. Once the solids light, there is no way to shut them off. If I'm not mistaken, separating the orbiter from the rest of the stack could (and probably would) be catastrophic. Once the SRBs are lit, you're committed to two minutes flight. Once they're gone, you can abort RTLS, TAL or ATO.
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#74
by
mkirk
on 03 Feb, 2007 23:03
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nathan.moeller - 3/2/2007 4:04 PM
kanathan - 3/2/2007 3:30 PM
I know that the shuttle crews train extensively for the normal abort modes that they might encounter, such as RTLS or ATO, but do they do any training for the contingency aborts such as "fast sep"?
I don't believe there is any fast separation abort. Once the solids light, there is no way to shut them off. If I'm not mistaken, separating the orbiter from the rest of the stack could (and probably would) be catastrophic. Once the SRBs are lit, you're committed to two minutes flight. Once they're gone, you can abort RTLS, TAL or ATO.
Crews are trained in Contingency Aborts as part of their early shuttle training (i.e. when they are ASCANS – Astronaut Candidates) and later as part of the mission specific training. So yes they get plenty of exposure to them.
It is a pretty specialized part of shuttle training mostly because of the numerous variables that come into play and the sensitive nature of the Contingency Aborts themselves. There are only a couple of training instructors for this particular type of training called "Ascent Procedures Specialists" who sit in on the sims when contingency cases are being trained and who provide the contingency training classes and briefings.
FAST SEP is a real procedure used in some of the Contingency cases for getting off of the tank very quickly – in about 5 seconds. There are situations that can result in very high sink rates which means a rapid buildup in dynamic pressure and thermal stress – both of which affect the ability to safely get off the tank and into an Entry configuration.
There are 7 methods for performing the FAST SEP procedure which are dependent on attitude and altitude.
One of the FAST SEP options is intended for getting off the entire stack (ET and SRBs) during first stage. This is done by separating the orbiter from the ET right at SRB thrust tail off (i.e. prior to SRB SEP).
Mark Kirkman
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#75
by
shuttlefan
on 03 Feb, 2007 23:33
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mkirk - 3/2/2007 6:03 PM
nathan.moeller - 3/2/2007 4:04 PM
kanathan - 3/2/2007 3:30 PM
I know that the shuttle crews train extensively for the normal abort modes that they might encounter, such as RTLS or ATO, but do they do any training for the contingency aborts such as "fast sep"?
I don't believe there is any fast separation abort. Once the solids light, there is no way to shut them off. If I'm not mistaken, separating the orbiter from the rest of the stack could (and probably would) be catastrophic. Once the SRBs are lit, you're committed to two minutes flight. Once they're gone, you can abort RTLS, TAL or ATO.
Crews are trained in Contingency Aborts as part of their early shuttle training (i.e. when they are ASCANS – Astronaut Candidates) and later as part of the mission specific training. So yes they get plenty of exposure to them.
It is a pretty specialized part of shuttle training mostly because of the numerous variables that come into play and the sensitive nature of the Contingency Aborts themselves. There are only a couple of training instructors for this particular type of training called "Ascent Procedures Specialists" who sit in on the sims when contingency cases are being trained and who provide the contingency training classes and briefings.
FAST SEP is a real procedure used in some of the Contingency cases for getting off of the tank very quickly – in about 5 seconds. There are situations that can result in very high sink rates which means a rapid buildup in dynamic pressure and thermal stress – both of which affect the ability to safely get off the tank and into an Entry configuration.
There are 7 methods for performing the FAST SEP procedure which are dependent on attitude and altitude.
One of the FAST SEP options is intended for getting off the entire stack (ET and SRBs) during first stage. This is done by separating the orbiter from the ET right at SRB thrust tail off (i.e. prior to SRB SEP).
Mark Kirkman
Mark, would it be pretty safe to separate from the stack if the SRB thrust were starting to tail off?
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#76
by
nathan.moeller
on 03 Feb, 2007 23:49
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Thanks for that Mark. I thought the abort option of "fast sep" meant that they separated the orbiter from the stack during the early part of the SRB burn. Guess I was kind of right...I didn't think there was any fast sep option during the first stage while the stack was in the dense lower atmosphere. Right before SRB sep or during the rest of the second stage ascent I can understand. But to be clear...my bad
Would that mean that the orbiter would have to go through a short re-entry scenario after the separtaion?
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#77
by
C5C6
on 04 Feb, 2007 02:48
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silly yet interesting question: when is the big countown clock at KSC turned off? it doesn't have day count or hundreds of hours so it can't remain on during the whole mission
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#78
by
nathan.moeller
on 04 Feb, 2007 14:01
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C5C6 - 3/2/2007 9:48 PM
silly yet interesting question: when is the big countown clock at KSC turned off? it doesn't have day count or hundreds of hours so it can't remain on during the whole mission
It runs through the countdown and the first few hours after launch.
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#79
by
TJL
on 04 Feb, 2007 14:51
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Was STS-116 the last planned mission to include the Spacehab module?
I see that STS-118 which is carrying a similar ISS payload, does not show Spacehab...thank you.
