Space Shuttle Return to Flight - Pt. 2

[ozspace]

According to Spaceflight Now:<br />"Kennedy Space Center spokewoman Jessica Rye says extra time needed to complete paperwork has delayed this morning's move of Discovery. The rollback is now targeted to start around 6 a.m. EDT."

 

[henryhallam]

Rollback has now begun.

 

[earth_bound_misfit]

I wonder if the crawler driver is listening to Willie Nelson's "On the road again". <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>

 

[drwayne]

Probably Sammy Hagar's<br /><br />"I Can't Drive 55"<br /><br />Cus he can't! <br /><br />Yes, I am in a silly mood!<br /><br />Wayne<br /><br /> <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[got_mmh]

13 cycles is the max of the acceptable range. I BELIEVE that the inability to maintain ullage pressure concern stemmed from the possibility of the LH2 Vent valve leaking and that was exonerated as not an issue. THAT would have been a problem and that was why until the second tanking test plans were in work to replace the LH2 vent valve. But as long as your system is pressurized and has no leaks, then that's your pressure at T-0 thru MECO as you aren't pressurizing during flight. It wouldn't matter how many cycles it takes as long as it maintains pressure. The designers weren't concerned about more cycles, the people on console seeing something different were worried. <br />

 

[bobw]

<font color="yellow">as you aren't pressurizing during flight</font><br /><br />It sure is pressurized during flight. This is from a shuttle tech page at NASA that I have copied to my hard drive. I can't be reading this wrong, can I?<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>In the engine, the liquid hydrogen cools various engine components and in the process is converted to gaseous hydrogen. The majority of this gaseous hydrogen is burned in the engine; the smaller portion is directed back to the external tank to maintain liquid hydrogen tank pressure. The flow of gaseous hydrogen back to the external tank begins at the turbine outlet of the LPFT. Gaseous hydrogen tapped from this line first passes through two check valves and then splits into two paths, each containing a flow control orifice. One of these paths also contains a valve normally controlled by one of three pressure transducers located in the liquid hydrogen tank.<br /><br /><br /> In the engine, a small portion of the liquid oxygen is diverted into the oxidizer heat exchanger. In the heat exchanger, heat generated by the high-pressure oxidizer turbopump is used to convert liquid oxygen into gaseous oxygen, which is directed back to the external tank to maintain oxidizer tank pressure. The flow of gaseous oxygen back to the external tank begins at the outlet of the heat exchanger. From this point, gaseous oxygen passes through a check valve and then splits into two paths, each containing a flow control orifice. One of these paths also contains a valve that normally is controlled by one of three pressure transducers located in the liquid oxygen tank. Downstream of the two flow control orifices and the pressure control valves, the gaseous oxygen lines empty into the orbiter gaseous oxygen pressurization manifold. This single line exits the orbiter at the gaseous oxygen pressurization disconnect and passes through the orbiter/external tank gaseous oxygen umbilical into the</p></blockquote> <div class="Discussion_UserSignature"> </div>

 

[got_mmh]

So here is my concern with posting this information. I was responding to post about questions regarding tanking test 1. Because I work External Tank I have REALLY accurate info regarding that piece of hardware and the work going on with it and planned for it. What you guys are getting on this post amounts to 0.00001% of the whole story (maybe less). This issue is in very good hands by some of the smartest people this country has. I don't know where shuttle guy works, so I don't know where he is getting his information, when he last got, or where he fits into the need for it. He has lots of accurate and good info; I only mean to help with the ET and Debris discussion on this post.

 

[got_mmh]

Okay, this will be my last post regarding this. When I spoke with Lockheed Martin/ET project about the extra cycles they were not concerned with it as long as the tank had integrity (no leaks). I don't like posting this because the discussion lasted two weeks with lot's of twelve hour days, so there is no way I can summarize all of that on this site. LCC was based on history, not design requirement that it be less than 13. You are right SG; it was out of family because it has always been half or so. That was my comment, different equals bad. I know a lot of people are very uptight about this issue. It is my perspective (and my bias) along with the opinion of a lot of ET engineers, that people were overreacting with the caveat that there were no leaks through LH2 vent. If you saw my area after the tanking test I don't know how you could have come to a different conclusion.<br />

 

[shuttle_rtf]

Thanks SG - yeah I went with the three APU Hot Fire - and NASA PR confirmed a successful three APU test later in the day. One media guy said it was NASA PR that told him it was a single APU hot fire, and he wasn't best pleased. NASA HQ in DC seem to be a bit off with their info. Jessica Rye at KSC seems a lot better.

 

[giofx]

The crawler has stalled!<br /><br />1:35 p.m. EDT<br />Discovery's rollback has been stalled by a problem with the crawler-transporter. Engineers are working to fix the technical glitch, which has stopped the transporter as it neared the VAB this afternoon. <br /><br />2:30 p.m. EDT<br />The shuttle continues to be parked along the Kennedy Space Center crawlerway while technicians examine an overheated bearing within the transporter. NASA has two giant tracked crawler-transporters that were originally built for Apollo four decades ago.

 

[mrmorris]

<font color="yellow">"The crawler has stalled! "</font><br /><br />I have this vision of the other crawler going out to meet the first, and a <b>***really***</b> big set of jumper cables being brought into play... <img src="/images/icons/smile.gif" />

 

[shuttle_rtf]

Yeah, it's still stuck.<br /><br />Here's a quote:<br /><br />Workers opened up panels on the vehicle, known as a "crawler," to figure out what was wrong, said NASA spokesman Bruce Buckingham. It is unclear how long the repairs will take

 

[shuttle_rtf]

Ha, that would make a pic. <br /><br />That would be one big arse "On Tow" sign <img src="/images/icons/smile.gif" />

 

[rybanis]

Oh God! How much wind would it take to blow over a shuttle standing up on the crawler? <div class="Discussion_UserSignature"> </div>

 

[shuttle_rtf]

Luckily the crawler is moving again and she's nearly inside the VAB.<br /><br />http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=83&start=1

 

[shuttle_rtf]

She's safely back in the VAB now.

 

[haywood]

How common is an overheated bearing?<br />It seems that Discovery can't catch a break.<br />But I'm relieved to hear that She's back in the barn.<br />

 

[shuttle_rtf]

During a part time job inbetween Uni, I spent a Saturday morning lubing and greasing up some bearings on a shut down conveyer belt. These were 4 inch diameter bearings and wow did they take some lube. Wonder how big these bearings on the Crawler are!<br /><br />Can't believe ABC news called the VAB the "Shuttle Hanger"

 

[CalliArcale]

They do that all the time, but it seems like such an inadequate word for all that the VAB is and does. Then again, in a sense it really *is* a hangar, and quite possibly the biggest one in the world. I'd rather call it the Saturn V hangar, though, because it was Saturn V that drove the requirements for such an incredibly huge building. If designed specifically for Shuttle, it would probably be a lot shorter. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[redgryphon]

If NASA opts for a shuttle derived heavy lift vehicle with the payload mounted above the ET, (e.g. Ares or Magnum) then that extra height in the VAB could become very useful indeed.

 

[haywood]

SG...what's all this concern about Raffaello and the mechanical fasteners?<br />I thought everything was all packed up in the Transfer Vehicle and ready to go.<br />Is this a new concern or something that has cropped up after additional study? (did I just repeat myself?)<br />

 

[najab]

Thread split at this point.