Shuttle Questions Q & A (Part 3)

• #1040 by mkirk on 24 Sep, 2007 13:59
• Quote

  jeff122670 - 23/9/2007  7:10 PM
  
  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?
  
  Jeff

  
  During STS-1 the arm was retracted just prior to comming out of the built in hold at T-9 minutes and the ET vent valve was allowed to continue to vent on its own until ET LO2 Pressurization.  It was assumed that during that short period no significant ice accumulation would occur on the vent valve louvers.
  
  After STS-1 flew they realized that ice was a big problem and was attributed to the tile damage that occured on the orbiter.
  
  Begining with STS-2 the GOX ARM ws modified to more efficently pump in warmed GN2 to the valve area, and vent off the gaseous oxygen.  It was also decided that the arm would be retracted later in the countdown (just prior to LO2 vent valve closure and tank pressurization) in an effort to keep the valve warm for as long as possible and to minimize the opportunity for ice formation.
• #1041 by parham55 on 24 Sep, 2007 16:25
• Thanks Lee Jay.  Those tight detailed pictures are great!
• #1042 by Jones36 on 29 Sep, 2007 19:47
• Is there any photo's or videos anywhere detailing the landing gear/tires from 51-D?
• #1043 by BigKiai on 02 Oct, 2007 17:09
• Two Questions:
  
  What is that grid of connections for at the left rear side of the orbiter in the picture above?
  
  Why does pad processing take so long - why does the shuttle sit at the pad for weeks before launch?
  
  Thanks,
  
  Mike
• #1044 by DaveS on 02 Oct, 2007 17:19
• Quote

  BigKiai - 2/10/2007  7:09 PM
  What is that grid of connections for at the left rear side of the orbiter in the picture above?

  It's the so called T-0(pronounced T zero) umbilical connections. There's a set on the right side of the orbiter.
  
  

  Quote

  BigKiai - 2/10/2007  7:09 PM
  Why does pad processing take so long - why does the shuttle sit at the pad for weeks before launch?
  

  There's much work that needs to be done out at the pad, many operations that take a long time. Below is a link to a list of the various operations that are done once the stack arrives at the pad and is harddown: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=2629&start=1#M37882
• #1045 by BigKiai on 02 Oct, 2007 21:20
• Has there ever been a case where one of the T-0 umbilical connections did not separate mechanically, and then got ripped out on launch? Does the launch power down / cancel if the they don't separate?
• #1046 by Jim on 02 Oct, 2007 22:50
• Quote

  BigKiai - 2/10/2007  5:20 PM
  
  Has there ever been a case where one of the T-0 umbilical connections did not separate mechanically, and then got ripped out on launch? Does the launch power down / cancel if the they don't separate?

  
  Not on the shuttle.  They separate at liftoff, there is no going back
• #1047 by BigKiai on 02 Oct, 2007 23:13
• Hypothetically, what happens if one does not separate as planned on liftoff?
• #1048 by tnphysics on 02 Oct, 2007 23:19
• Probably get ripped apart.
• #1049 by ChrisGebhardt on 02 Oct, 2007 23:41
• Quote

  BigKiai - 2/10/2007  7:13 PM
  
  Hypothetically, what happens if one does not separate as planned on liftoff?

  
  Once the countdown reaches T-0 and the SRBs ignite, the shuttle is launching... whether the T-0 umbilicals have separated or not.
• #1050 by stockman on 03 Oct, 2007 00:17
• Quote

  Trekkie07 - 2/10/2007  7:41 PM
  
  

  Quote

  BigKiai - 2/10/2007  7:13 PM
  
  Hypothetically, what happens if one does not separate as planned on liftoff?

  
  Once the countdown reaches T-0 and the SRBs ignite, the shuttle is launching... whether the T-0 umbilicals have separated or not.

  
  Yep... one of the astronauts (forget which one) said a while back that once the solids ignite you're definitely going somewhere!!
• #1051 by Jim on 03 Oct, 2007 02:46
• Quote

  BigKiai - 2/10/2007  7:13 PM
  
  Hypothetically, what happens if one does not separate as planned on liftoff?

  
  They will come off, it is just a weight on a pulley to pull it off
• #1052 by BigKiai on 03 Oct, 2007 03:00

• Quote

  Jim - 2/10/2007 7:46 PM

  Quote

  BigKiai - 2/10/2007 7:13 PM Hypothetically, what happens if one does not separate as planned on liftoff?

  They will come off, it is just a weight on a pulley to pull it off

   

  What if the pulley system fails and one or more of the cables remain attached. Could they hit one of the main engines and damage them?

   Do they have a contingency plan in place for this?

   Mike

• #1053 by nathan.moeller on 03 Oct, 2007 03:50
• Quote

  stockman - 2/10/2007  7:17 PM
  
  

  Quote

  Trekkie07 - 2/10/2007  7:41 PM
  
  

  Quote

  BigKiai - 2/10/2007  7:13 PM
  
  Hypothetically, what happens if one does not separate as planned on liftoff?

  
  Once the countdown reaches T-0 and the SRBs ignite, the shuttle is launching... whether the T-0 umbilicals have separated or not.

  
  Yep... one of the astronauts (forget which one) said a while back that once the solids ignite you're definitely going somewhere!!

  
  I think it was Endeavour's former flow director who said 'When those kick on, you're gonna go somewhere.  The shuttle will not stay at the pad.'  I forget his name but I remember it clearly.
• #1054 by Jorge on 03 Oct, 2007 06:00
• Quote

  BigKiai - 2/10/2007  10:00 PM
  
  

  Quote

  Jim - 2/10/2007 7:46 PM

  Quote

  BigKiai - 2/10/2007 7:13 PM Hypothetically, what happens if one does not separate as planned on liftoff?

  They will come off, it is just a weight on a pulley to pull it off

  What if the pulley system fails and one or more of the cables remain attached. Could they hit one of the main engines and damage them?

  Do they have a contingency plan in place for this?

  Mike

  
  Not specifically. If an engine fails due to contact with a T-0 umbilical, the contingency plan is "abort RTLS at T+2:30" - same as for any other engine failure during first stage.
• #1055 by STS-500Cmdr on 03 Oct, 2007 06:17
• The guy Nathan is referring to was Al Strainer who was the Site Test Conductor for Endeavour, 'Tip' Talone was the flow director--this was at the time of the 1994 Discovery channel program-which nathanmoeller is referring to.
• #1056 by Lee Jay on 04 Oct, 2007 14:47
• About 1/4 of the way in on this video is camera 050.  It shows the T-0 umbilical disconnecting at launch.
  
  http://www.space-multimedia.nl.eu.org/index.php?option=com_content&task=view&id=2424&Itemid=2
• #1057 by psloss on 04 Oct, 2007 15:57
• Quote

  Lee Jay - 4/10/2007  10:47 AM
  
  About 1/4 of the way in on this video is camera 050.  It shows the T-0 umbilical disconnecting at launch.
  
  http://www.space-multimedia.nl.eu.org/index.php?option=com_content&task=view&id=2424&Itemid=2
  

  The other one is normally shown on camera 049/149...
  
• #1058 by Jorge on 04 Oct, 2007 19:06
• Quote

  pad rat - 4/10/2007  9:22 AM
  
  The T-0 umbilicals are mounted on a sturdy steel carrier plate that engages latches on the orbiter's fuselage. It's likely that failure of a carrier plate to separate would result in significant structural damage to the area around the T-0 panel. Since there are wiring and plumbing runs on the inside wall of that area, there would likely be electrical faults, possibly a bus drop, pneumatic leaks, and hydraulic leaks. There would be so many strikes against the vehicle/crew that I'd venture to say a successful RTLS would be out of the question.

  
  I would think the exterior umbilicals would be the weak point, and would rip loose long before the carrier plate. So you would wind up with the shuttle lifting off with the carrier plate still firmly latched to the orbiter, trailing a bunch of torn umbilicals.
• #1059 by stockman on 04 Oct, 2007 19:18
• Quote

  Jorge - 4/10/2007  3:06 PM
  
  

  Quote

  pad rat - 4/10/2007  9:22 AM
  
  The T-0 umbilicals are mounted on a sturdy steel carrier plate that engages latches on the orbiter's fuselage. It's likely that failure of a carrier plate to separate would result in significant structural damage to the area around the T-0 panel. Since there are wiring and plumbing runs on the inside wall of that area, there would likely be electrical faults, possibly a bus drop, pneumatic leaks, and hydraulic leaks. There would be so many strikes against the vehicle/crew that I'd venture to say a successful RTLS would be out of the question.

  
  I would think the exterior umbilicals would be the weak point, and would rip loose long before the carrier plate. So you would wind up with the shuttle lifting off with the carrier plate still firmly latched to the orbiter, trailing a bunch of torn umbilicals.

  
  
  why do I suddenly get the mental picture of the old lady driving away from the gas station with the gas nozzel and hoze still attached...