NASA seeks Shuttle exhaust waiver

• NASA seeks Shuttle exhaust waiver by Chris Bergin on 24 Aug, 2006 23:26
• http://www.nasaspaceflight.com/content/?cid=4731 - debut article by Joe for this site.
  
  Associated images.
  
  Document and four associated videos with the document on L2.
• #1 by Chris Bergin on 24 Aug, 2006 23:26

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• #2 by Chris Bergin on 24 Aug, 2006 23:29

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• #3 by Chris Bergin on 24 Aug, 2006 23:30

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• #4 by astrobrian on 24 Aug, 2006 23:56
• Is this waiver just a covering thier bases move or something else? After 1200 test fires I think if there was a defiante problem it would have been in process to be fixed during the 2 years down time they had. Kinda puzzles me. Granted for the flight that the video comes from, yes, there was something needing to be done about that
• #5 by psloss on 25 Aug, 2006 00:06
• A cutoff just before "launch commit" would be the most extreme scenario -- although this situation without the HBOI capability during shutdown was the case for all the FRFs, given their run time.
• #6 by psloss on 25 Aug, 2006 00:17
• Quote

  astrobrian - 24/8/2006  7:43 PM
  
  After 1200 test fires I think if there was a defiante problem it would have been in process to be fixed during the 2 years down time they had. Kinda puzzles me. Granted for the flight that the video comes from, yes, there was something needing to be done about that

  Don't know, although the test firings at Stennis have rarely involved three engine clusters.
  
  The videos on L2 are from different countdowns; the IR video is from the FRF prior to STS-26 (10 August 1988), although the effect that is obvious in the STS-68 abort video sure looks to be present (to differing degrees) in the FRFs I've seen shutdown video from.
  
• #7 by Shuttle Man on 25 Aug, 2006 00:27
• A good opening article from Joe.
• #8 by SimonShuttle on 25 Aug, 2006 16:25
• Thank goodness this site is still reporting space flight news, when the others all seem to be obsessed with that crappy former planet.
• #9 by Avron on 25 Aug, 2006 17:26
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  SimonShuttle - 25/8/2006  12:12 PM
  
  Thank goodness this site is still reporting space flight news, when the others all seem to be obsessed with that crappy former planet.

  
  
  What planet?..
• #10 by psloss on 25 Aug, 2006 17:32
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  Avron - 25/8/2006  1:13 PM
  
  

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  SimonShuttle - 25/8/2006  12:12 PM
  
  Thank goodness this site is still reporting space flight news, when the others all seem to be obsessed with that crappy former planet.

  
  
  What planet?..

  Why Earth, of course.  (And Jupiter.)
  
  (I say we take up a collection and form our own solar system.  Maybe we can get Chris to do the web site.)
  
• #11 by Chris Bergin on 25 Aug, 2006 19:15
• Quote

  astrobrian - 25/8/2006  12:43 AM
  
  Is this waiver just a covering thier bases move or something else?

  
  Covering the bases, I'd say.
• #12 by spaceshuttle on 26 Aug, 2006 18:47
• i was reading a (frozen) article about the aborts and the burnoff ignitor issues...they already have six ignitors: two in the back across from each other, two in the front across from each other, and two more in the back that point towards the middle(see attachments). they're gonna need more?
  
  

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• #13 by MKremer on 26 Aug, 2006 18:54
• Not so much 'more', maybe, as much as tweaking the timings and maybe duration (longer-lasting) of the existing ignitor locations.
  
• #14 by spaceshuttle on 26 Aug, 2006 19:00
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  MKremer - 26/8/2006  1:41 PM
  
  Not so much 'more', maybe, as much as tweaking the timings and maybe duration (longer-lasting) of the existing ignitor locations.
  

  
  cool! well, they should have them start up at t-12 or -15 to ENSURE enough time. besides, the used to start at t-8...
• #15 by MKremer on 26 Aug, 2006 19:18
• Don't need them earlier, but either staggered or to last longer through a possible shut down process.
• #16 by spaceshuttle on 26 Aug, 2006 19:39
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  MKremer - 26/8/2006  2:05 PM
  
  Don't need them earlier, but either staggered or to last longer through a possible shut down process.

  
  well, true...i just noticed that they do slow down and stop AT t-0
• #17 by Chris Bergin on 26 Aug, 2006 23:13
• Quote

  MKremer - 26/8/2006  7:41 PM
  
  Not so much 'more', maybe, as much as tweaking the timings and maybe duration (longer-lasting) of the existing ignitor locations.
  

  
  Yep, that's exactly it.
• #18 by Mark Max Q on 30 Aug, 2006 00:28
• This may be a stupid question, but are huge mechanical areas of the orbiter, such as the MPS, affected by the vibrations of a rollout, then rollback, brakes on, rollback out? Whole lotta shaking going on?
• #19 by Jim on 30 Aug, 2006 01:49
• Less than a launch
• #20 by Bruhn on 30 Aug, 2006 20:32
• Quote

  Mark Max Q - 29/8/2006  7:15 PM
  
  This may be a stupid question, but are huge mechanical areas of the orbiter, such as the MPS, affected by the vibrations of a rollout, then rollback, brakes on, rollback out? Whole lotta shaking going on?

  
  Yes, there are areas of the Orbiter and SSMEs that are effected by rollout induced vibrations.  It does subtract from the fatigue life of the systems.  Vibes aren't as much as launch like Jim stated, but fatigue damage is cumulative.  I've got a video of the SSMEs and other parts of the orbiter during rollout that really shows the parts shaking.  More than you would think.  I've been trying to get the video to Chris but its too big.
  
  Each track of the crawler, I don't know how much they weigh but its alot, slaps down on the ground in a steady rythm.  This excites the structure just as if it were a modal survey test.  You can tune the vibrations by changing the speed of the crawler, but not by much.