Shuttle Q&A Part 5

• #2480 by Jorge on 18 Jan, 2012 06:13
• Quote from: alk3997 on 18 Jan, 2012 04:15

  Quote from: Jorge on 18 Jan, 2012 00:31

  Quote from: OV-106 on 17 Jan, 2012 23:30

  It didn't have to be a "next-generation" shuttle.  There were ample ideas and studies performed on many system upgrades and modifications that were never implimented.
  
  The reasons varied of course, from the cost would have been prohibitive to sometimes changing things just to supposedly improve them (when more or less it was working fine or was understood) was not something the always fit within the other confines of the Program. 
  

  
  I remember the proposed SIGI upgrade. Very slick... but the costs of modifying the FSW to work with SIGI caused a lot of people to freak out. The assumption of a stable-platform IMU was pretty deeply baked-into the software. Re-verifying it would have been a bear.
  

  
  Prototype software had been made and we were actually "looking forward" to the challenge.  The SIGI was tested onboard using PGSCs to record the data (much as MAGR-S was tested).
  
  SIGI was actually very important from the keep GPCs flying until 2025 plan.  We would have off-loaded displays first (CAU) and then off-loaded Nav.  This way there would have been enough memory available to keep upgrading GPC flight software through 2025 (if the plan to do that had materialized).  Much much cheaper than new GPCs (and software).
  
  

  
  I was really looking forward to CAU, especially after getting to do some display evals in the SMS. (Also made some design inputs on the Orbit PFD, Att Tgt, and Rndz Task displays). Some of the designs live on in the Orion displays.
• #2481 by sivodave on 18 Jan, 2012 06:45
• Hi all.
  
  A question regarding proximity operations with the ISS.
  
  I'm reading that after the RPM the orbiter started a Twice Orbital Rate V Bar Approach (TORVA) to reas the V-Bar. In earlier missions to the ISS, like STS-88 it was instead used a Twice Orbital Rate R Bar Approach (TORRA).
  
  Could you please explain me which is the meanig of these two maneuvers? and why they were adopted?
  
  Thanks very much
  
  Davide
• #2482 by jeff122670 on 18 Jan, 2012 14:52
• "CDR, reconfigure heaters".......can anyone explain this call in the countdown?
  
  thanks!
• #2483 by Namechange User on 18 Jan, 2012 15:06
• Quote from: jeff122670 on 18 Jan, 2012 14:52

  "CDR, reconfigure heaters".......can anyone explain this call in the countdown?
  
  thanks!
  

  
  Switching from one string to another, possibly turning them on/off, etc.  It just depends. 
• #2484 by Jorge on 18 Jan, 2012 15:10
• Quote from: sivodave on 18 Jan, 2012 06:45

  Hi all.
  
  A question regarding proximity operations with the ISS.
  
  I'm reading that after the RPM the orbiter started a Twice Orbital Rate V Bar Approach (TORVA) to reas the V-Bar. In earlier missions to the ISS, like STS-88 it was instead used a Twice Orbital Rate R Bar Approach (TORRA).
  
  Could you please explain me which is the meanig of these two maneuvers? and why they were adopted?
  
  Thanks very much
  
  Davide
  

  
  Long answer, think it's in here, if not I'll deal with it later:
  
  http://forum.nasaspaceflight.com/index.php?topic=27598.0
• #2485 by mkirk on 18 Jan, 2012 15:49
• Quote from: jeff122670 on 18 Jan, 2012 14:52

  "CDR, reconfigure heaters".......can anyone explain this call in the countdown?
  
  thanks!
  

  
  If your are talking about the call around T-5 minutes, then it is a call to have the commander turn off the flash evaporator feed line heaters.  Prior to this point in the count you had cryo loading of the external fuel tank (thru the aft compartment) and thermal conditioning of the MPS (main propulsion system) taking place - making the belly of the orbiter (located next to the extremely cold external tank) and the aft compartment of the orbiter, very cold.  The flash evaporator feed lines run under the payload bay (i.e. along the belly) and into the aft compartment.
  
  Mark Kirkman
• #2486 by jeff122670 on 19 Jan, 2012 10:15
• Thanks Mark...i was hoping you would chime in!!!!
  
  
  
  Jeff
• #2487 by STS-85 on 20 Jan, 2012 03:34
• I asked on the Historical thread re: STS-51C but maybe it's better to try here:
  What was the bank limitation for the orbiter, coming around the hack? The commentator says on STS-51C landing coverage that Discovery is in a bank of 87 degrees at one point - I didn't think they ever went that far - was it a mistake, by the commentator, or was that the case? In the video, it does indeed look remarkably accurate...
• #2488 by sivodave on 20 Jan, 2012 05:53
• Quote from: Jorge

  Long answer, think it's in here, if not I'll deal with it later:
  
  http://forum.nasaspaceflight.com/index.php?topic=27598.0
  

  
  Hi Jorge.
  
  I've to say that I've found out about TORVA and TORRA just reading few days ago History of Space Shuttle Rendezvous...a very inspiring document I've to say...plenty of good description.
  
  TORVA and TORRA are mentioned at page 137 where it says that twice orbital rate fly-arounds permitted faster transfers with lower propellant consuption and plume impingment. Also it says that the faster rate prevented the Sun from continously staying in the field of view of the crew.
  
  So I'd like to have some more info about it. Why TORVA and TORRA are better and in what they exactly consists? I see from the diagrams in the quoted document that TORRA and TORVA are performed in the maneuver for passing from the +R bar to the +V bar.
  
  Does the adjective "twice" simply mean that the the passage from +R bar to +V bar is just done at twice the speed than what was done before the maneuver was introduced? And which is the difference between orbital rate and velocity?
  
  Thanks very much
  
  Davide
• #2489 by mkirk on 20 Jan, 2012 08:22
• Quote from: STS-85 on 20 Jan, 2012 03:34

  I asked on the Historical thread re: STS-51C but maybe it's better to try here:
  What was the bank limitation for the orbiter, coming around the hack? The commentator says on STS-51C landing coverage that Discovery is in a bank of 87 degrees at one point - I didn't think they ever went that far - was it a mistake, by the commentator, or was that the case? In the video, it does indeed look remarkably accurate...
  

  
  I'd have to see and hear the coverage you are talking about, but most likely he is referring to the (HTA) hac turn angle to go before the orbiter is lined up on final - in other words the number of degrees around the HAC circumference.
  
  The orbiter's guidance system had specific constraints on roll angle in both the supersonic and subsonic phase of flight while on the HAC (ranging from 30 to 60 degrees) - these were intended to prevent the 1.8 G limit from be exceeded.
  
  Mark Kirkman
• #2490 by STS-85 on 21 Jan, 2012 04:31
• This is the transcript..
  
  PAO: Approaching the Heading Alignment Circle, and Discovery will be beginning the sweeping left turn, coming around for runway 15… left bank 45 degrees now, 40.000 feet, on Heading Alignment Circle, normal energy… orbiter systems in good shape, 36,000 feet, .7 mach on the Heading Alignment Circle, bank 77 degrees… now 87 degrees… airspeed about 264 knots, range 8 miles… and they’ve reported the sonic boom at the Cape… on the Heading Alignment Circle airspeed 258, altitude 24,000 feet, range 9 miles…
• #2491 by starbird on 21 Jan, 2012 06:34
• I'm pretty sure he's talking about some turn angle, not bank. There are clips of the landing on youtube and none of them show any extreme bank angles.
  
  
• #2492 by Jorge on 21 Jan, 2012 07:42
• Quote from: sivodave on 20 Jan, 2012 05:53

  Quote from: Jorge

  Long answer, think it's in here, if not I'll deal with it later:
  
  http://forum.nasaspaceflight.com/index.php?topic=27598.0
  

  
  Hi Jorge.
  
  I've to say that I've found out about TORVA and TORRA just reading few days ago History of Space Shuttle Rendezvous...a very inspiring document I've to say...plenty of good description.
  
  TORVA and TORRA are mentioned at page 137 where it says that twice orbital rate fly-arounds permitted faster transfers with lower propellant consuption and plume impingment. Also it says that the faster rate prevented the Sun from continously staying in the field of view of the crew.
  
  So I'd like to have some more info about it. Why TORVA and TORRA are better and in what they exactly consists?

  
  I'm not sure what you are asking.
  
  

  Quote

  I see from the diagrams in the quoted document that TORRA and TORVA are performed in the maneuver for passing from the +R bar to the +V bar.

  
  TORRA is a maneuver from the +Rbar to the -Rbar. TORVA is a maneuver from the +Rbar to the +Vbar.
  
  

  Quote

  Does the adjective "twice" simply mean that the the passage from +R bar to +V bar is just done at twice the speed than what was done before the maneuver was introduced?

  
  Yes.
  
  

  Quote

  And which is the difference between orbital rate and velocity?

  
  "Orbital rate" is angular velocity while "velocity", in this context, is tangential velocity. Tangential velocity is just the angular velocity times the range (omega cross r).
• #2493 by sivodave on 22 Jan, 2012 11:55
• Quote from: Jorge

  Quote from: sivodave on 01/20/2012 06:53 AM
  
      Quote from: Jorge
  
          Long answer, think it's in here, if not I'll deal with it later:
  
          http://forum.nasaspaceflight.com/index.php?topic=27598.0
  
  
      Hi Jorge.
  
      I've to say that I've found out about TORVA and TORRA just reading few days ago History of Space Shuttle Rendezvous...a very inspiring document I've to say...plenty of good description.
  
      TORVA and TORRA are mentioned at page 137 where it says that twice orbital rate fly-arounds permitted faster transfers with lower propellant consuption and plume impingment. Also it says that the faster rate prevented the Sun from continously staying in the field of view of the crew.
  
      So I'd like to have some more info about it. Why TORVA and TORRA are better and in what they exactly consists?
  
  
  I'm not sure what you are asking.
  

  
  Hi Jorge
  
  I read better the document and I've understood that TORVA and TORRA were used for all MIR and ISS missions. I had understood that this kind of approaches were implemented in the early docked missions to MIR or ISS. So my question has not reason of being! sorry about that.
  
  Last thing: twice orbital rate/velocity, i suppose they refer to twice the orbital rate/velocity of the target (ie: ISS) or of the chaser (Shuttle)?
  
  Thanks very much
  
  Regards
  
  Davide
   
• #2494 by Jorge on 22 Jan, 2012 18:07
• Quote from: sivodave on 22 Jan, 2012 11:55

  
  Last thing: twice orbital rate/velocity, i suppose they refer to twice the orbital rate/velocity of the target (ie: ISS) or of the chaser (Shuttle)?
  

  
  Doesn't matter. The value of twice orbital rate used (0.13 deg/sec) was rounded to the nearest hundredth. We're talking prox ops here. The difference in orbital rate between the two vehicles was far less than the margin of rounding.
• #2495 by mkirk on 23 Jan, 2012 08:29
• Quote from: STS-85 on 21 Jan, 2012 04:31

  This is the transcript..
  
  PAO: Approaching the Heading Alignment Circle, and Discovery will be beginning the sweeping left turn, coming around for runway 15… left bank 45 degrees now, 40.000 feet, on Heading Alignment Circle, normal energy… orbiter systems in good shape, 36,000 feet, .7 mach on the Heading Alignment Circle, bank 77 degrees… now 87 degrees… airspeed about 264 knots, range 8 miles… and they’ve reported the sonic boom at the Cape… on the Heading Alignment Circle airspeed 258, altitude 24,000 feet, range 9 miles…
  

  
  Yeah he definitely misspoke - I watched the video and my best "GUESS" is he read the numbers for the brake (as in speed brake which might have been opening to 77 percent)...I really have no idea, and I only know enough to make me very dangerous.
  
  As for your original question, the roll/bank during this part of the TAEM Guidance phase (subsonic, on the HAC, and not flying RTLS guidance limits) is ideally around 45 degrees with guidance limiting roll commands to a maximum of 60 degrees.
  
  While normally bank on the HAC is around 45-ish degrees, high winds at altitude (such as a strong tail wind) may require a larger bank angle.
  
  Mark Kirkman
• #2496 by STS-85 on 23 Jan, 2012 15:10
• OK thanks -
  wouldn't be the first or last time PAO mis-spoke lol ..
  
  
• #2497 by jeff122670 on 24 Jan, 2012 21:40
• another random question, but does anyone know the launch that Rob Navias commented that the orbiter was "flying down hwy (XXX)"  (he was referring to the STS mission number as the "why").
  
  completely random, but i can't find the flight commentary.
  
  thanks!!!
• #2498 by catdlr on 24 Jan, 2012 23:04
• Quote from: jeff122670 on 24 Jan, 2012 21:40

  another random question, but does anyone know the launch that Rob Navias commented that the orbiter was "flying down hwy (XXX)"  (he was referring to the STS mission number as the "why").
  
  completely random, but i can't find the flight commentary.
  
  thanks!!!
  

  
  Steer to this location:
  http://forum.nasaspaceflight.com/index.php?topic=19476.msg504345#msg504345
  
  Here is the YouTube link.  The comment is made at 3:50 into the video.
  
  
• #2499 by jeff122670 on 25 Jan, 2012 00:19
• THANKS!