Shuttle Q&A Part 5

• #3280 by elmarko on 02 Oct, 2014 10:45
• I'd be surprised if nobody has asked this question before, but since this is now a 5 part thread with lots of posts, it's not easy to check.
  
  What is the theoretical maximum altitude of the Shuttle? Obviously we have the Hubble's altitude of just over 600 km as an maximum that was actually reached during the STS program, but is there anywhere that details any possibilities higher than that?
  
  Obviously the question marks are how much payload is in the bay to begin with, and how much dV the OMS has for circularisation and deorbit. So, let's go with an empty payload bay, a Hubble-ish weight in the payload bay, and something half way between. Any ideas?
• #3281 by Jim on 02 Oct, 2014 11:00
• Quote from: elmarko on 02 Oct, 2014 10:45

  I'd be surprised if nobody has asked this question before, but since this is now a 5 part thread with lots of posts, it's not easy to check.
  
  What is the theoretical maximum altitude of the Shuttle? Obviously we have the Hubble's altitude of just over 600 km as an maximum that was actually reached during the STS program, but is there anywhere that details any possibilities higher than that?
  
  Obviously the question marks are how much payload is in the bay to begin with, and how much dV the OMS has for circularisation and deorbit. So, let's go with an empty payload bay, a Hubble-ish weight in the payload bay, and something half way between. Any ideas?
  

  
  100lb per nautical mile was the rule of thumb for trades.
• #3282 by elmarko on 02 Oct, 2014 12:22
• Quote from: Jim on 02 Oct, 2014 11:00

  100lb per nautical mile was the rule of thumb for trades.
  

  
  Thanks Jim. Presumably that only works until the OMS tanks are full. Which would be reached first? A full OMS tank or an empty cargo bay?
  
  Hubble weighed 24,000 ish lbs, and a quick Google reveals the maximum payload weight to be 60,000+ lbs
• #3283 by Jim on 02 Oct, 2014 13:45
• Quote from: elmarko on 02 Oct, 2014 12:22

  
  Thanks Jim. Presumably that only works until the OMS tanks are full. Which would be reached first? A full OMS tank or an empty cargo bay?
  

  
  No, the rule of thumb took at that into account if I recall.
• #3284 by Kim Keller on 02 Oct, 2014 13:54
• Quote from: elmarko on 02 Oct, 2014 10:45

  I'd be surprised if nobody has asked this question before, but since this is now a 5 part thread with lots of posts, it's not easy to check.
  
  What is the theoretical maximum altitude of the Shuttle? Obviously we have the Hubble's altitude of just over 600 km as an maximum that was actually reached during the STS program, but is there anywhere that details any possibilities higher than that?
  
  Obviously the question marks are how much payload is in the bay to begin with, and how much dV the OMS has for circularisation and deorbit. So, let's go with an empty payload bay, a Hubble-ish weight in the payload bay, and something half way between. Any ideas?
  

  
  I dimly recall that the TPS could only tolerate a descent from 600 miles altitude, due to increased velocity at entry interface.
• #3285 by Specifically-Impulsive on 13 Oct, 2014 12:36
• An OMS payload bay kit was planned which would have greatly increased the available delta-v.  When I was working on the SMS in the early 80s there were scars in the models related to this kit.  It never flew though.

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• #3286 by Jim on 13 Oct, 2014 20:55
• Quote from: Specifically-Impulsive on 13 Oct, 2014 12:36

  An OMS payload bay kit was planned which would have greatly increased the available delta-v.  When I was working on the SMS in the early 80s there were scars in the models related to this kit.  It never flew though.
  

  
  Direct insertion eliminated the need for the kits.
• #3287 by DaveS on 14 Oct, 2014 21:42
• Does somebody happen to be familiar with the X_O coordinates of the FWD/aft Orb/ET attachment points?
• #3288 by AnalogMan on 14 Oct, 2014 22:18
• Quote from: DaveS on 14 Oct, 2014 21:42

  Does somebody happen to be familiar with the X_O coordinates of the FWD/aft Orb/ET attachment points?
  

  
  From the SLWT bible drawings:
  
  Forward attachment X_O = 338.045
  Aft attachments     X_O = 1317    Y_O ±96.50
  
  (these are orbiter referenced, i.e. not X_T values)
  
  http://forum.nasaspaceflight.com/index.php?topic=14350.msg317169#msg317169
• #3289 by DaveS on 14 Oct, 2014 22:44
• Quote from: AnalogMan on 14 Oct, 2014 22:18

  Quote from: DaveS on 14 Oct, 2014 21:42

  Does somebody happen to be familiar with the X_O coordinates of the FWD/aft Orb/ET attachment points?
  

  
  From the SLWT bible drawings:
  
  Forward attachment X_O = 338.045
  Aft attachments     X_O = 1317    Y_O ±96.50
  
  (these are orbiter referenced, i.e. not X_T values)
  
  http://forum.nasaspaceflight.com/index.php?topic=14350.msg317169#msg317169
  

  Thanks. Do you happen to know the length of the nosecap and the NLG doors?
• #3290 by DaveS on 19 Oct, 2014 01:34
• Now I need to know the height/width of the mid and aft vent doors.
• #3291 by Hog on 21 Oct, 2014 19:12
• I just noticed in video #3 on the Discovery press day L2 videos, that there is a few moments where the Ascent Abort selector is visible.(pause at 14:15 of the video)
  L2 video:  http://forum.nasaspaceflight.com/downloads/l2/Discovery_Media_Event_Pt3.wmv
  
  
  The Abort Mode selection order on the dial of Discovery as of 2011 with her glass cockpit is "RTLS/OFF/ATO/TAL".
  
  A picture taken during STS-51F Challenger, where you can se that Abort To Orbit(ATO) is selected. On Challenger the Abort selector's sequence is "OFF/RTLS/TAL-AOA/ATO".
  
  Were these changes made during the "glass cockpit" upgrading?
  
  What was the rational for the order of the Abort Modes on the dials?

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• #3292 by Specifically-Impulsive on 21 Oct, 2014 22:59
• I remember this change being made (late 90s?).  IIRC, the idea was that after the change you could abort RTLS by just pushing the button without having to move the switch.    It's been a long time but there may have been rationale about the possibility of moving the switch too far and selecting an undesirable abort mode during the RTLS window.  I'll see if I can dig anything up, seems like there was more to this story.
• #3293 by alk3997 on 22 Oct, 2014 02:42
• Quote from: Hog on 21 Oct, 2014 19:12

  I just noticed in video #3 on the Discovery press day L2 videos, that there is a few moments where the Ascent Abort selector is visible.(pause at 14:15 of the video)
  L2 video:  http://forum.nasaspaceflight.com/downloads/l2/Discovery_Media_Event_Pt3.wmv
  
  The Abort Mode selection order on the dial of Discovery as of 2011 with her glass cockpit is "RTLS/OFF/ATO/TAL".
  
  A picture taken during STS-51F Challenger, where you can se that Abort To Orbit(ATO) is selected. On Challenger the Abort selector's sequence is "OFF/RTLS/TAL-AOA/ATO".
  
  Were these changes made during the "glass cockpit" upgrading?
  
  What was the rational for the order of the Abort Modes on the dials?
  

  
  The glass cockpit upgrade did not touch the abort switch since the glass cockpit upgrade was initially transparent to the GPC flight software.  The GPC flight software initially did not know if it had a MEDS (glass) cockpit or a MCDS (original) cockpit on the other side.
  
  As you can imagine moving what each position meant on the abort selector would feedback into the flight software.  I'm trying to remember how the rotary was wired.   But, the reason for the change was to prevent inadvertently selecting an RTLS instead of a TAL and, I think, also to make bailout less likely to be accidentally pressed (pressing my memory there).
• #3294 by Specifically-Impulsive on 22 Oct, 2014 03:04
• That sounds more like it.  Left for RTLS, right for TAL, harder to make a mistake.
• #3295 by Hog on 22 Oct, 2014 13:32
• Thank you gents.
   
  The following pics are courtesy of NASA and show the Abort Selector of the 4 orbiters(I couldnt find a verified Columbia cockpit photo) You will need to zoom in to see the Abort Selector in tehse pics.

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• #3296 by Hog on 31 Oct, 2014 17:00
• The engines of STS-93 Columbia.  STS-93 was the last time that these SSME's were flown.
  SSME#2019/Powerhead#2020 (19th flight) Engine Position#1 (Center)
  SSME#2031/Powerhead#2028 (17th flight) Engine Position#2 (Left)
  SSME#2012/Powerhead#2025 (12th flight) Engine Position#3 (Right)
  
  Since all 3 SSME's flown on STS-93 were of Block II design, the SSME Advanced Health Management System(AHMS) was not part of STS-93.
  
  AHMS "Phase In"
  •1st Flight - 1 AHMS controller in monitor-only mode, 2 Block II controllers
  • Accomplished on STS -116 on 12/9/2006
  
  • 2nd Flight - 1 AHMS controller in redline-active mode, 1 AHMS controller in
  monitor-only mode
  • Accomplished on STS -117 on 6/8/2007
  
  • 3rd Flight - 3 AHMS controllers in redline-active mode
  • Accomplished on STS -118 on 8/8/2007
  
  Pratt & Whitney Overview and Advanced Health Management Program (circa 2006)
  http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080023322.pdf
  
  From Wayne Hale's blog titled "STS-93 We dont need anymore of those" http://waynehale.wordpress.com/2014/10/26/sts-93-we-dont-need-any-more-of-those/
  
  "about a minute after launch, the booster officer and his team recognized the fact that the right engine turbine temperatures and speeds were higher than normal. They correctly identified that this might be due to a nozzle leak, but there was another potential anomaly that also had the same signature. If the oxidizer pump started to lose ‘efficiency’ (blades rubbing, pump clogging, etc.) it would look the same. As the SSME controller commanded mixture ratio changes to keep up with the loss of efficiency on the pump, the turbines would reach their temp limit and the engine would have to throttle down to prevent a shutdown: this was called ‘thrust limiting’. Until the SSME went into thrust limiting, the Booster team could not tell the difference between an oxidizer turbine/pump efficiency loss and a nozzle leak. The instrumentation just wasn’t precise enough to know what was going on. Jon and his team correctly identified that the engine was running off nominally (‘off tags’) but could not quantify it. Later on, when the FDO asked him, the Booster officer had to report that none of the engines were ‘suspect’. All these terms were precisely defined in the flight rules and had specific actions for the flight controllers and crew to take to maximize safety. But this leak was too small for any of that."
  
  
  My question, would having AHMS installed on STS=93 Columbia helped to make the Booster Officer/Team to diagnose the SSME issues even quicker and/or with more certainty?
• #3297 by Specifically-Impulsive on 01 Nov, 2014 00:35
• I don't believe so.  I think AHMS mostly added vibration shutdown, not a factor in STS-93.
• #3298 by iskyfly on 06 Nov, 2014 13:57
• One of the calls made to the crew during ascent was something called "droop". What does this mean?
  
  Thanks
  
  
  edit- Also mentioned here- http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940017386.pdf
  
• #3299 by psloss on 06 Nov, 2014 14:59
• Quote from: iskyfly on 06 Nov, 2014 13:57

  One of the calls made to the crew during ascent was something called "droop". What does this mean?
  
  Thanks
  
  
  edit- Also mentioned here- http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940017386.pdf
  

  If you have L2, there's a great reference for Shuttle ascents/aborts (flight procedures handbook, circa OI-30 / 2005):
  http://forum.nasaspaceflight.com/index.php?topic=3466.0
  
  It's detailed in Section 2.5.2; ascent boundary calls in 4.3.3.2.
  
  This is also covered in the public workbooks for intact and contingency aborts posted on the flight data file landing page:
  http://www.nasa.gov/centers/johnson/news/flightdatafiles/index.html
  
  Specific files:
  http://www.nasa.gov/centers/johnson/pdf/383447main_intact_ascent_aborts_workbook_21002.pdf
  http://www.nasa.gov/centers/johnson/pdf/383441main_contingency_aborts_21007_31007.pdf