Post by: Chris Bergin on 04/01/2006 02:20 am
Shuttle Q&A Part 1 (http://forum.nasaspaceflight.com/index.php?topic=625)
Shuttle Q&A Part 2 (http://forum.nasaspaceflight.com/index.php?topic=2030)
Shuttle Q&A Part 3 (http://forum.nasaspaceflight.com/index.php?topic=6156)
Shuttle Q&A Part 4 (http://forum.nasaspaceflight.com/index.php?topic=10600.0)
Shuttle Q&A Part 5 (http://forum.nasaspaceflight.com/index.php?topic=17437.0)
Post by: psloss on 04/01/2006 02:55 am
First question: what's the difference between a Redundant Set Launch Sequencer (RSLS) hold and an RSLS abort? Is it the difference between a hold by the RSLS before or after main engine start? Or is there more to it than that?
And second question has to do with the terms used in some of these cases over the years...for holds inside of T-31 seconds but prior to main engine start, I've heard the word "breakout" used in at least one case and "cutoff" used more often...is there any distinction between the two given the context? Or do they mean different things?
Thanks,
Philip Sloss
Post by: mkirk on 04/01/2006 03:33 pm
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psloss - 31/3/2006 8:55 PM
OK, the ET diffuser "what ifs" have me wondering about elaborating on some countdown terms I've heard over the years, but never seen much discussion.
First question: what's the difference between a Redundant Set Launch Sequencer (RSLS) hold and an RSLS abort? Is it the difference between a hold by the RSLS before or after main engine start? Or is there more to it than that?
And second question has to do with the terms used in some of these cases over the years...for holds inside of T-31 seconds but prior to main engine start, I've heard the word "breakout" used in at least one case and "cutoff" used more often...is there any distinction between the two given the context? Or do they mean different things?
Thanks,
Philip Sloss
Okay. here is Countdown 101
HOLD is defined by the LCCs (launch commit criteria) as "an interuption of the countdown for any reason. Holds may be preplanned or occur for unfavorable weather, problem investigation, repair of hardware, or correction of conditions unsatisfactory for launch or flight".
CUTOFF is defined as "Automatic or manual command to stop the launch sequencer after initiation of the "Automatic Launch Sequence Start".
In Practice:
A HOLD can be called at anytime between the start of the countdown at T-43 Hours until T-31 seconds. The NTD (Nasa Test Director) will then stop the count at the approprate point. Begining at T-9 Minutes there are a handfull of GLS (ground launch sequencer) milestones or Hold points where the countdown can be stopped at. These predetermined points are based on vehicle conditions that can be maintained for a period of time during the countdown without adverse effects on hardware.
These Milestones are:
T-9 minutes 00 seconds GLS Sequence Start
T-7 minutes 30 seconds OAA (Orbiter Access Arm) Retract
T-5 minutes 00 seconds APU Start
T-4 minutes 00 seconds Purge Sequence 4
T-2 minutes 55 seconds LOX Tank Pressurization
T-1 minute 57 seconds LH2 Terminate Replenish
T-31 seconds RSLS (Redundant Set Launch Sequencer) Start
After T-5 minutes if a hold is called the clock will continue to T-31 seconds and hold there unless a request is made to stop at one of the other milestones such as T- 2 minutes 55 seconds to avoid pressurizing the liquid oxygen tank.
After T-31 seconds the only option is a "Cutoff" which would result in a recycle to a more stable vehicle configuration at T-20 minutes at which point the scrub procedures would be implemented.
An "RSLS Abort" is called when the countdown is "Cutoff" after the first main engine start command is issued. This occurs when engine number 3 is given the command to start at T-6.6 seconds (engines start in reverse order 3-2-1 in 120 millisecond intervals).
I would have to know the context of your second question about "Brakeouts". I think you are referring to the GLS breakout points after T-31 seconds and these are just points where a specified GLS sequence would occur if the countdown is stopped. These are based on the vehicle's configuration at the "Cutoff" point.
Mark Kirkman
Post by: Jim on 04/01/2006 04:32 pm
Post by: Mark Max Q on 04/01/2006 07:23 pm
Does the orbiter pick up the count after the T-9:00 hold and thus be in alignment, ready for the T-31?
Post by: psloss on 04/01/2006 10:31 pm
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mkirk - 1/4/2006 10:33 AMThanks, as usual, Mark. I'm familiar with the GLS milestones, but your answer is a good primer.
I would have to know the context of your second question about "Brakeouts". I think you are referring to the GLS breakout points after T-31 seconds and these are just points where a specified GLS sequence would occur if the countdown is stopped. These are based on the vehicle's configuration at the "Cutoff" point.
Mark Kirkman
I think I've heard it a couple of times, but the specific count I'm thinking of is one of the several STS-51 scrubs; general reference:
http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/archives/sts-51.html
In this case, it was the attempt on 24 July 1993; actually, looking at the description there, I think you've already hit on it:
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Launch was delayed on Saturday, July 24, due to a problem with the right hand solid rocket booster (SRB). The ground launch sequencer detected an unacceptably slow speed rate of a hydraulic power unit located inside the shuttle's right hand solid rocket booster. The hydraulic power unit (HPU) was replaced and retested.
I believe the SRB HPUs are started at T-25 seconds; shortly thereafter, I believe the call (not sure if this was the GLS console operator, but that would be my guess) was "we have a breakout." I believe the clock stopped at T-19 seconds, but I'm not sure that's necessarily a high priority action (so maybe the cutoff was given before T-19).
(Someday, I'll digitize this, but don't have the tapes handy these days.)
So if I'm reading your description, the call was indicating a GLS breakout that had followed a RSLS hold...is that close?
Thanks,
Philip Sloss
Post by: psloss on 04/01/2006 10:46 pm
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Jim - 1/4/2006 11:32 AMThat occurred memorably on STS-93 -- the 20 July 1999 attempt was stopped by manual call just before main engine start; in the background one can hear a call to "give cutoff," almost overlapped by the same request from the NTD. It was amazing, even considering all the practice, how quickly that happened, since it sounds like the initial call came in right around T-10 seconds.
I have been on console and have heard the NTD request "GLS give cutoff". I don't remember all the details. What would happen after T-31sec that it would have to be a manual cutoff. It wasn't the range.
(Not sure what console, but it had to be MPS-related, since that was a spike in the hydrogen concentration in the aft compartment -- subsequently attributed to a sensor misreading.)
Post by: psloss on 04/01/2006 10:51 pm
http://science.ksc.nasa.gov/shuttle/countdown/count.html
FWIW.
Post by: Chris Bergin on 04/01/2006 11:01 pm
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psloss - 1/4/2006 10:46 PM
That occurred memorably on STS-93 -- the 20 July 1999 attempt was stopped by manual call just before main engine start; in the background one can hear a call to "give cutoff," almost overlapped by the same request from the NTD. It was amazing, even considering all the practice, how quickly that happened, since it sounds like the initial call came in right around T-10 seconds.
(Not sure what console, but it had to be MPS-related, since that was a spike in the hydrogen concentration in the aft compartment -- subsequently attributed to a sensor misreading.)
And here's the video for that (first link)
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=442&start=1
From the audio, you can hear something being said at T-9.5 seconds, with the "Cutoff, give cutoff....cutoff is given" through to T-7 seconds.
Post by: Jim on 04/02/2006 01:25 pm
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Mark Max Q - 1/4/2006 1:23 PMHow does the hand off to the orbiter for Auto Sequence Start happen?Does the orbiter pick up the count after the T-9:00 hold and thus be in alignment, ready for the T-31?
The GLS instructs the GPC's at T-31 initiate autosequenct
Post by: mkirk on 04/02/2006 05:05 pm
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Chris Bergin - 1/4/2006 5:01 PMQuotepsloss - 1/4/2006 10:46 PM
That occurred memorably on STS-93 -- the 20 July 1999 attempt was stopped by manual call just before main engine start; in the background one can hear a call to "give cutoff," almost overlapped by the same request from the NTD. It was amazing, even considering all the practice, how quickly that happened, since it sounds like the initial call came in right around T-10 seconds.
(Not sure what console, but it had to be MPS-related, since that was a spike in the hydrogen concentration in the aft compartment -- subsequently attributed to a sensor misreading.)
And here's the video for that (first link)
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=442&start=1
From the audio, you can hear something being said at T-9.5 seconds, with the "Cutoff, give cutoff....cutoff is given" through to T-7 seconds.
For STS-93 I was in a part of the MCC (Mission Control Center) called the SCA (Sim Control Area) where many of the training instructors gather to watch over the data on consoles identical to those in the FCR (flight control room). While I remember the actual STS-93 launch quite well for obvious reasons, I don't really recall many of the details for the two scrubs. After a while many of the missions seem to just run together.
The proper call for a Cutoff is "CGLS, Give Cutoff". Both the GLS console operator and the NTD are spring loaded to respond to those words immediately. For that particular scrub the CHGD (hazardous gas detection system console) operator made a call "CGLS, Give Cutoff" and I believe what you here after that is the NTD echoing the command. CHGD had noticed a spike of 640 ppm in the Hydorgen concentration in the orbiter's aft compartment. This could be indicative of a fuel leack...as it turned out I believe they decided that it was bad data from the sensors and we could have launched with no problem...I will get into the problems on the actual launch when I have more time to review my notes and tapes.
To answer Jim's Question:
"What would happen after T-31sec that it would have to be a manual cutoff. It wasn't the range."
Basically any parameter not directly monitored by the GLS or RSLS would require a manual cutoff. One of the ovious ones as you said would be a range issue.
One of the more recent times that I can recall would have been the STS-88 launch attempt. MCC and LCC were both looking at APU hydraulics data and while MCC cosidered it to be within limits the LCC needed more time to reach that conclusion. Holding at T-31, a go was finally given to pick up the count but by that time the short launch window had elapsed...by a couple of seconds as I recall. This meant we had used up our performance margin of availabel fuel in the external tank. MCC tracks this and immediately John Shannon the Flight Director called "NTD, Houston Flight, WE ARE NO GO FOR LAUNCH"...NTD responded with a Cutoff request. This was not an automatic cutoff because the hold time constraint of "LOX performace margin" is not a parameter that the GLS or RSLS would track.
As I said in another thread...that launch scrub frightened us a little bit...you just don't want to run around with your hair on fire that late in a countdown. There were a lot of lesssons learned from the STS-88 launch attempt.
I can also speculate that maybe a known condition that was masked, biased, or bypassed by the GLS software prior to T-31 and then later shows behavior that is suddenly erratic or beyond the waivered value, would require a manual cutoff.
I should add if I understand Firing Room Protocol correctly; even if a systems operator sees something that the GLS/RSLS should be calling an automatic cutoff for, he/she should back that up with the verbal request for a cutoff to the CGLS console. You should never ASSUME that the GLS will automatically take care of it.
Mark Kirkman
Post by: mkirk on 04/02/2006 05:18 pm
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Mark Max Q - 1/4/2006 1:23 PM
How does the hand off to the orbiter for Auto Sequence Start happen?
Does the orbiter pick up the count after the T-9:00 hold and thus be in alignment, ready for the T-31?
The way the GLS (ground launch sequencer) and RSLS (redundant set launch sequencer...the onboard computers) interact is actually a little more complex than you might think. At T-31 second the GLS will give the onboard computers the GO for Auto Sequence and at T-28 seconds the onboard computers check to make sure the go was given.
While the RSLS is "driving the count" both the GLS and RSLS will issue there own commands and both will cross check each other.
For instance at T-27.92 seconds the RSLS will command the Vent Door Sequence (all vent doors open) this is an onboard command.
At T-28 seconds the GLS will issue commands to start the SRB HPUs (Hydraulic power units) and then perform a gimbal test of the SRB nozzles...these are gorund based commands.
In other words, after T-31 seconds the GLS still has work to do and it does its tasks and then reports to the RSLS that from its perspective it is "Go For Launch". At the same time the on board computers via the RSLS will have a set of tasks to perform such as the vent sequence, setting the throttle commands, opening engine valves, or commanding the onboard master events controller to arm the SRB ignition and T-0 release pyros.
Mark Kirkman
Post by: psloss on 04/02/2006 05:26 pm
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mkirk - 2/4/2006 1:05 PMAt the time, it was said that the primary haz gas detector "burped" some hydrogen that it re-detected...I don't have the primary sources, but I stumbled onto a few STS-93 press briefing excerpts, including the countdown status briefing between the first and second attempts which discuss this scrub. Assuming these will convert over, I can post them...Chris?
The proper call for a Cutoff is "CGLS, Give Cutoff". Both the GLS console operator and the NTD are spring loaded to respond to those words immediately. For that particular scrub the CHGD (hazardous gas detection system console) operator made a call "CGLS, Give Cutoff" and I believe what you here after that is the NTD echoing the command. CHGD had noticed a spike of 640 ppm in the Hydorgen concentration in the orbiter's aft compartment. This could be indicative of a fuel leack...as it turned out I believe they decided that it was bad data from the sensors and we could have launched with no problem...I will get into the problems on the actual launch when I have more time to review my notes and tapes.
Philip Sloss
Post by: Chris Bergin on 04/02/2006 07:36 pm
Post by: psloss on 04/05/2006 12:50 pm
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mkirk - 2/4/2006 1:05 PMFWIW,
One of the more recent times that I can recall would have been the STS-88 launch attempt. MCC and LCC were both looking at APU hydraulics data and while MCC cosidered it to be within limits the LCC needed more time to reach that conclusion. Holding at T-31, a go was finally given to pick up the count but by that time the short launch window had elapsed...by a couple of seconds as I recall. This meant we had used up our performance margin of availabel fuel in the external tank. MCC tracks this and immediately John Shannon the Flight Director called "NTD, Houston Flight, WE ARE NO GO FOR LAUNCH"...NTD responded with a Cutoff request. This was not an automatic cutoff because the hold time constraint of "LOX performace margin" is not a parameter that the GLS or RSLS would track.
As I said in another thread...that launch scrub frightened us a little bit...you just don't want to run around with your hair on fire that late in a countdown. There were a lot of lesssons learned from the STS-88 launch attempt.
We've posted a clip of the NASA TV coverage of this launch attempt now; the excerpt runs from T-5 minutes and counting through the cutoff and beginning of the recycle. The "no go" call by the flight director to NTD is obscured by the PAO, though I think it can be barely heard.
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=2078
Post by: psloss on 04/10/2006 09:34 pm
http://science.ksc.nasa.gov/shuttle/countdown/video/
The quick, specific question is which OPF bay is this? (I imagine that this could be deduced based on which orbiter is where in its processing flow, but I'll throw it out, anyway.) The general question is whether there's an online reference for which OTV cameras are in what location? Some of them I've picked up from spectating over the years, but some of the ones in the OPF (090s) and VAB (080s) bays I'm a little shakier on. (Although some of the VAB cameras are on the roof, which are a bit more obvious.)
Thanks,
Philip Sloss
Post by: Jim on 04/10/2006 10:22 pm
Just found out it is an ITAR doc.
Post by: Davie OPF on 04/10/2006 10:26 pm
Post by: SRBseparama on 04/11/2006 02:43 am
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Davie OPF - 10/4/2006 5:26 PM
I think that's Discovery, with her KU Band Antenna in OPF3.
Why's it sticking out like that? It's just asking for a lamp to be knocked on to it! :o ;)
Post by: Rocket Guy on 04/11/2006 02:55 am
Edit: I will add though, that of course could be any of them, but as testing is underway on that one specifically they may have their cameras trained on it.
Post by: Jim on 04/11/2006 02:56 am
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SRBseparama - 10/4/2006 10:43 PMQuoteDavie OPF - 10/4/2006 5:26 PMI think that's Discovery, with her KU Band Antenna in OPF3.Why's it sticking out like that? It's just asking for a lamp to be knocked on to it! :o ;)
It is being tested
Post by: GLS on 04/11/2006 10:00 am
I have some questions and I hope someone can anwser them:
1) Is this new (or improved) ET still called SLWT or is there a new designation?
2) Are FRCS "exclusive" to an orbiter or are they switched around like the OMS pods?
3) What is the STS number of mission 41D? I think it was STS-14 before the RSLS abort, and 41F was STS-16. But after the missions were merged, I don't know if the "new" 41D sticked to STS-14, or if it changed to STS-16 because it moved to the 0884 launch slot (STS-16).
Post by: DaveS on 04/11/2006 10:05 am
2)FRCS modules switched around the vehicles
3)No idea. Someone else around here should be able to answer this one though.
Post by: GLS on 04/11/2006 10:17 am
Post by: Jim on 04/11/2006 11:45 am
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GLS - 11/4/2006 6:00 AM#1 post so let's see if it works...I have some questions and I hope someone can anwser them:1) Is this new (or improved) ET still called SLWT or is there a new designation?2) Are FRCS "exclusive" to an orbiter or are they switched around like the OMS pods?3) What is the STS number of mission 41D? I think it was STS-14 before the RSLS abort, and 41F was STS-16. But after the missions were merged, I don't know if the "new" 41D sticked to STS-14, or if it changed to STS-16 because it moved to the 0884 launch slot (STS-16).
That was the whole point of the new system, there wasn't an STS-XXX. It was STS 41-D and the XXX didn't apply any more
Post by: Flightstar on 04/11/2006 12:50 pm
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Davie OPF - 10/4/2006 5:26 PM
I think that's Discovery, with her KU Band Antenna in OPF3.
Yes, it's OPF 3.
Post by: GLS on 04/15/2006 11:41 am
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Jim - 11/4/2006 12:45 PM
That was the whole point of the new system, there wasn't an STS-XXX. It was STS 41-D and the XXX didn't apply any more
They still used the STS-XXX but it wasn't as a mission name, but as a "launch slot" based on when the vehicle could fly (I think...), and as missions got delayed and moved around, they would change slots. Example: the first planned launch slot in 86 was STS-33 on OV-099. Originally mission 61D (SL-4 or something) was to launch in 33, but after all the delays and moving around mission 51L launched in that slot. 34 was for mission 61E (ASTRO-1) on OV-102, slot 35 had mission 61F (Ulysses/Centaur-G Prime) on OV-099 and 36 was for mission 61G (Galileo/Centaur-G Prime) on OV-104.
Does anyone know the answer for my STS-14/STS-16 question?
Post by: Jim on 04/15/2006 03:24 pm
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GLS - 15/4/2006 7:41 AMQuoteJim - 11/4/2006 12:45 PMThat was the whole point of the new system, there wasn't an STS-XXX. It was STS 41-D and the XXX didn't apply any moreThey still used the STS-XXX but it wasn't as a mission name, but as a "launch slot" based on when the vehicle could fly (I think...), and as missions got delayed and moved around, they would change slots. Example: the first planned launch slot in 86 was STS-33 on OV-099. Originally mission 61D (SL-4 or something) was to launch in 33, but after all the delays and moving around mission 51L launched in that slot. 34 was for mission 61E (ASTRO-1) on OV-102, slot 35 had mission 61F (Ulysses/Centaur-G Prime) on OV-099 and 36 was for mission 61G (Galileo/Centaur-G Prime) on OV-104.Does anyone know the answer for my STS-14/STS-16 question?
It wasn't offical
Post by: mkirk on 04/15/2006 05:32 pm
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Jim - 11/4/2006 6:45 AMQuoteGLS - 11/4/2006 6:00 AM#1 post so let's see if it works...I have some questions and I hope someone can anwser them:1) Is this new (or improved) ET still called SLWT or is there a new designation?2) Are FRCS "exclusive" to an orbiter or are they switched around like the OMS pods?3) What is the STS number of mission 41D? I think it was STS-14 before the RSLS abort, and 41F was STS-16. But after the missions were merged, I don't know if the "new" 41D sticked to STS-14, or if it changed to STS-16 because it moved to the 0884 launch slot (STS-16).
That was the whole point of the new system, there wasn't an STS-XXX. It was STS 41-D and the XXX didn't apply any more
That was a pretty confusing transition back then. I was only a kid at the time but thanks to some highly placed freinds I accumulated a good collection of checklists and operating procedures as each flight rolled around. I have plenty of documents that show one or both of the designations at that time. For instance I have checklists and coundown documents for STS-11, 12 and I believe a couple with STS-13. By the time 41D was ready to fly I guess they had the new system down because all of the 41D material I have used the new designation. To the best of my knowledge I don't have anything with a STS-14 or higher designation until the first return to flight (post 51L) in 1988.
Mark Kirkman
Post by: Martin FL on 04/15/2006 11:18 pm
Post by: hyper_snyper on 04/15/2006 11:44 pm
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Martin FL - 15/4/2006 7:18 PMIf Shuttle missions are STS', what do we think CLV/CEV missions will be designated?
Exploration Transportation System (ETS)
...at least that's what ATK has on their safe simple soon website
Post by: Jon_Jones on 04/16/2006 12:20 am
I was thinking that project constellation is the same designation as project apollo... if that is so, then maybe the designations will be constellation 1,2,3,4,5,6...
but I think I like the ETS better. reminds me of STS.
Post by: Jim on 04/16/2006 04:27 am
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hyper_snyper - 15/4/2006 7:44 PMQuoteMartin FL - 15/4/2006 7:18 PMIf Shuttle missions are STS', what do we think CLV/CEV missions will be designated?
Exploration Transportation System (ETS)
...at least that's what ATK has on their safe simple soon website
That is ATK's name in their proposal. Only used on their website. It is not the NASA's
There was a little hubris in NASA using "STS" and "NSTS"
Post by: Rocket Ronnie on 04/16/2006 07:33 am
Post by: Tahii on 04/16/2006 08:33 am
Post by: Stowbridge on 04/18/2006 02:31 pm
Post by: Jim on 04/18/2006 02:35 pm
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Stowbridge - 18/4/2006 10:31 AMCan anyone list the evolution of the SRBs from STS-1 to current day?
SRM pre 51-L
RSRM STS-26 and on
There have been material changes here and there but nothing that would change the configuration
Post by: Pointman 7 on 04/25/2006 11:21 pm
Post by: astrobrian on 04/26/2006 12:06 am
Post by: shuttlefan on 04/26/2006 12:07 am
Post by: Pointman 7 on 04/26/2006 12:12 am
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astrobrian - 25/4/2006 7:06 PM
Its the aft External Tank connections to the Shuttle if what I am seeing is correct
LOL. Yeah, I think I worked that out ;)
I want to know what each electrical connections aft port connectors I'm seeing here.
Post by: mkirk on 04/26/2006 01:11 am
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Pointman 7 - 25/4/2006 7:12 PMQuoteastrobrian - 25/4/2006 7:06 PM
Its the aft External Tank connections to the Shuttle if what I am seeing is correct
LOL. Yeah, I think I worked that out ;)
I want to know what each electrical connections aft port connectors I'm seeing here.
I'll give it a try;
On the left: The big silver colored circle at the top is the 17 inch LH2 (Liquid Hydrogen) feedline disconnect, the dark circle immediately below and to the right is the 2 inch LH2 pressurization disconnect, to the left of that with the redish color is the 4 inch LH2 recirculization line connection, and the big circle at the bottom is the electrical monoball - this is where the electrical interfaces between the orbiter and the ET are made, examples would be the low level ECO sensor instrumentation as well as all the other LH2 liquid level sensors, pressurization, vent and flow control valves etc...
On the right: The big silver circle is the 17 inch LO2 (Liquid Oxygen) feedline disconnect, the dark circle immediately below and to the left is the 2 inch LO2 pressurization disconnect, below that is the electrical monoball umbilical - again this is the electrical interface between the orbiter and ET, examples would be the liquid level sensors for the LO2 tank (the LO2 ECO sensors are not actually in the tank like the LH2 ECO sensors are, they are on the orbiter side of the 17 inch disconnect), valve operation etc...
The holes for the ET/Orbiter tie bolts are not really visible in this picture, but you have three around each of the 17 inch feedline diconnects one at the bottom (6 o'clock postition) and the other at the 10 and 2 o'clock.
Aside from the ET intrumentation, SRB related instrumentation also goes thru these connection points.
Mark Kirkman
Post by: Jim on 04/26/2006 01:40 am
Post by: dmc6960 on 04/26/2006 03:56 pm
Post by: Jim on 04/26/2006 04:09 pm
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dmc6960 - 26/4/2006 11:56 AMWhy are both the LH2 and LO2 feedlines 17 inches if the engines require 6 times the amount of hydrogen than they do oxygen?
That is by weight, but there still a volumetric difference
But the design was for ease. Only one disconnect needed to be designed.
Post by: GLS on 04/28/2006 01:44 pm
1) I was giving a quick read at the CAIB report the other day, and on STS 107 there was a 2.08sec, window protect maneuver at T+127.7 using RCS F1U, F2U, F3U. WHAT IS THIS???
2) On cameras ET207 and ET208, there's some *lines* in the image at about 60-90sec into the flight. Is that a reflection or what?
Post by: psloss on 04/28/2006 01:54 pm
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GLS - 28/4/2006 9:44 AM
I have a couple more questions (actually I have more, but I'll ask them later...):
1) I was giving a quick read at the CAIB report the other day, and on STS 107 there was a 2.08sec, window protect maneuver at T+127.7 using RCS F1U, F2U, F3U. WHAT IS THIS???
If you're referring to the forward RCS firing at SRB separation, I believe that's done to minimize the amount of SRB separation motor exhaust deposited on the orbiter windows -- if you recall the ET camera video from STS-112, which was essentially in the line of fire of the right SRB, the camera's window was "fogged over" by the separation motor plume. Early in the program, some crews remarked right after SRB sep about how much "crud" was left on the windows (I believe that was the word used by Paul Weitz on STS-6). If I recall correctly, someone noted that re-entry tended to "clean" that film off the windows.
Someone here can probably say how long ago the FRCS firing was put into use, but it predates 107.
Edit: Looking at the 112 ET cam footage again, I'm not sure I see the FRCS firing.
Philip Sloss
Post by: GLS on 04/28/2006 02:09 pm
EDIT: Wait a minute, I doesn't shield anything because the burn is after SRB sep.... It just cleans the windows...
Post by: Zoomer30 on 04/28/2006 04:07 pm
Post by: mkirk on 04/28/2006 04:22 pm
The idea of possibly inducing a pitch rate...in the direction that the SRBs are traveling when they seperate...took some getting used to.
That aside, the technique works very well and has reduced the windshield glare for entry and landing that used to be caused by the residue from the SRB SEP motors. Glare is a big factor the STA (Shuttle Training Aircraft) pilot considers when evaluating approaches at the shuttle runway prior to every launch for RTLS or prior to the deorbit burn for End of Mission landings. It goes without saying you really need to be able to see the runway. With that residue on the window the sun could really cause some glare according to some commanders.
Mark Kirkman
Post by: mkirk on 04/28/2006 07:07 pm
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Jim - 28/4/2006 12:20 PMQuoteZoomer30 - 28/4/2006 12:14 PMCant find the post for some reason, but one thing that was not mentioned was that the shuttle, no matter what orbital declination it will be in, MUST go to orbit "heads down, wing level" until SRB sep. Or in other words, upside down. The reason is its the only safe way to get rid of the SRBs. If they shuttle flew on top of the stack, the SRBs would slam into the wings. A few mins after SRB sep the shuttle does that roll that does place the ship on top, thats so they can tap into the TDRS sat for ground comm (they started that in '98 I think, so they could close ground stations that are used during ascent).I think the previous poster thought the shuttle was the only ship to do a roll after launch. All rockets have done this, its just more visable with the shuttle.
It has nothing to do the SRB's. It is to reduce the loads on the wings. The roll back to orbiter on top is to increase performance, a better TDRSS link was just a fallout.
The Shuttle Q &A thread is were questions like this go
The roll to heads down after liftoff has many side benefits but the primary reason for it is to minimize structural loads between the ET and the orbiter. The heads down attitude does provide a slight negative angle of attack which minimizes loads while not sacrificing too much performance.
There is no reason SRB SEP can not occur from the heads up attitude other than a loss in overall performance (up mass).
The roll back to heads up which occurs at about five and a half minutes into the flight was primarily driven by the closure of the Bermuda tracking station. It provides an early handoff from MILA to TDRS East. The second roll is actually a slight performance loss. The first flight to do this was STS-87. Rolling back to heads up was always part of the TAL procedures but additional study and certification was needed prior to incorporating it into Nominal Ascents. In fact the shuttle is no longer certified to stay heads down on a Nominal Ascent!!!
OTHER benefits of the Roll to Heads down is: visible horizon for the crew (helps with abort and manual flying procedures), G-loading on crew is more favorable, communication with the ground stations is not blocked by the ET.
Mark Kirkman
Post by: Chris Bergin on 04/28/2006 10:54 pm
Post by: psloss on 04/28/2006 11:18 pm
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mkirk - 28/4/2006 3:07 PM(Hope it's OK to bring this over from the locked thread...)
OTHER benefits of the Roll to Heads down is: visible horizon for the crew (helps with abort and manual flying procedures), G-loading on crew is more favorable, communication with the ground stations is not blocked by the ET.
Hi Mark,
Weren't some studies done/consideration given to a heads-up ascent? I want to say this was associated with other ascent changes using the 5-segment SRBs (like ATO off the pad), but maybe it's unconnected...have to go do some digging for references...
This reference is only available offline, though the first page (w/abstract) can be downloaded:
http://www.aiaa.org/content.cfm?pageid=406&gTable=japaperimportPre97&gID=25979
And an interesting old Usenet thread (not sure about the accuracy); here's one post:
http://groups.google.com/group/sci.space.shuttle/msg/590bae76a518a1ac
(I'd be interested in anything you know about this.)
Thanks,
Philip Sloss
Post by: hyper_snyper on 04/28/2006 11:53 pm
During STS-121 or any other subsequent mission, there are going to be cameras on the ground and on the tank to spot falling foam. If a big chunk of foam flies free and hits the orbiter and damages the TPS (heaven forbid) during the early stages of ascent and it's spotted by the cameras nice and clear do the mission controllers have the option of telling the crew to abort TAL or RTLS? If it's obvious damage has been done, I don't see how it would be a good idea to let them continue to orbit.
Post by: psloss on 04/29/2006 12:11 am
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hyper_snyper - 28/4/2006 7:53 PMI can't give a straight answer, but I'd always assumed that Columbia's RCC damage would have been catastrophic even in a TAL entry given its similarity to a regular entry -- and actually, I believe some low-energy TALs can be more extreme thermally...not sure about RTLS (though it has it's own risks).
I have a quick shuttle question.
During STS-121 or any other subsequent mission, there are going to be cameras on the ground and on the tank to spot falling foam. If a big chunk of foam flies free and hits the orbiter and damages the TPS (heaven forbid) during the early stages of ascent and it's spotted by the cameras nice and clear do the mission controllers have the option of telling the crew to abort TAL or RTLS? If it's obvious damage has been done, I don't see how it would be a good idea to let them continue to orbit.
Post by: mkirk on 04/29/2006 06:01 pm
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psloss - 28/4/2006 6:18 PMQuotemkirk - 28/4/2006 3:07 PM(Hope it's OK to bring this over from the locked thread...)
OTHER benefits of the Roll to Heads down is: visible horizon for the crew (helps with abort and manual flying procedures), G-loading on crew is more favorable, communication with the ground stations is not blocked by the ET.
Hi Mark,
Weren't some studies done/consideration given to a heads-up ascent? I want to say this was associated with other ascent changes using the 5-segment SRBs (like ATO off the pad), but maybe it's unconnected...have to go do some digging for references...
This reference is only available offline, though the first page (w/abstract) can be downloaded:
http://www.aiaa.org/content.cfm?pageid=406&gTable=japaperimportPre97&gID=25979
And an interesting old Usenet thread (not sure about the accuracy); here's one post:
http://groups.google.com/group/sci.space.shuttle/msg/590bae76a518a1ac
(I'd be interested in anything you know about this.)
Thanks,
Philip Sloss
I sat in on a few meetings in the 1999-2000 timeframe concerning 5 Segment Bossters. Nobody ever metnioned heads up profile to my knowledge. The biggest concerns I recall involved getting the vehicle recertifed for the new ascent trajectory. Structural changes to the tank would be needed, new aerodynamic modeling (since for example, the SRB nose cones would be higher relative to the current stack which in trun meant the shock waves would be hitting the tank in a different location), processing was a concern since you would have extra segements in the VAB (increased risk, processing to stacks would have exceeded the current certification for the VAB in terms of allowable propellant).
There was a preliminary belief that with 5 segment boosters Black Zones would be significantly reduced but I don't think they would have been eliminated. Single engine failure in first stage would have resulted in an ATO capability I believe.
I read your Usenet thread and that doesn't seem to ring true to me. I will read the AIAA paper in a couple days and see if that makes sense...I can say I never heard anyone discuss heads up as a performance advantage but that paper is pretty old (1988) so I'll look into it.
Mark Kirkman
Post by: mkirk on 04/29/2006 06:29 pm
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hyper_snyper - 28/4/2006 6:53 PM
I have a quick shuttle question.
During STS-121 or any other subsequent mission, there are going to be cameras on the ground and on the tank to spot falling foam. If a big chunk of foam flies free and hits the orbiter and damages the TPS (heaven forbid) during the early stages of ascent and it's spotted by the cameras nice and clear do the mission controllers have the option of telling the crew to abort TAL or RTLS? If it's obvious damage has been done, I don't see how it would be a good idea to let them continue to orbit.
No, that is definately not an option and actually although it sounds on the suface like it might be a good idea, it is actually a very dangerous and bad idea.
Ascent is only 8.5 minutes long, during that time someone would have to see the foam debris, assess it size, mass, velocity, density, and total impact energy. Then you would have to determine if it hit a critical area of the orbiter or not. Then you have to decide if the impact actually caused damage or is a safety of flight issue...what systems affected?, do you have potential control issues?, do you have thermal issues?
Then even if you could do all that you have to pass the abort request up to the crew in a timely manner.
Tha abort profiles the shuttle uses are well trained and understood, but they all impose significant trade offs in risk. RTLS for example is less thermally severe than a TAL but it is far more dynamic than most TALs. If you have critical systems affeceted by the impact such as impending lose of hydraulics then you want to get on the ground quickly...loss of a thermal window pain means you want a less thermally severe profile. My point is you would have to evaluate all of this "on the fly" and hope you don't make your situation worse.
The right thing to do is fly with our current abort philosophy and if performance and systems allow it, you go to orbit and then evaluate the situation. Lets say there is significant damage to the vehicel structure...you would rather think thru exactly how you want to fly (control issues, thermal, or opt for safe haven on ISS) and then return as opposed to attempting an abort without a complete understanding of the vehicle's status and your ability to survive the profile.
Going to space so you can "reconfigure" is exactly what you would want to do!!!! Contrary to Ascent and Entry, on orbit operations give you time to think and evaluate. This is similar to the airplane pilot's desire to gain altitude when a problem occurs...altitude gives you time to evaluate...Shuttle does this to the extreme...
Another point: The flight control team in the MCC (mission control center) does not watch the video in real time. There are some TV monitors in the room but everyone is trained to look at their data. The video can deceive you!!! On top of that the very high quality video is not transmitted in real time...it is recorded and evaluated frame by frame by many engineers on the photo analysis team about a day after launch.
Mark Kirkman
Post by: GLS on 04/29/2006 07:24 pm
2) On cameras ET207 and ET208, there's some *lines* in the image at about 60-90sec into the flight. Is that a reflection or what?
Post by: Jim on 04/29/2006 07:33 pm
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GLS - 29/4/2006 3:24 PMAnd can anyone anwser the second question?2) On cameras ET207 and ET208, there's some *lines* in the image at about 60-90sec into the flight. Is that a reflection or what?
Where are we to view these videos?
Post by: mkirk on 04/30/2006 12:06 am
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GLS - 29/4/2006 2:24 PM
And can anyone anwser the second question?
2) On cameras ET207 and ET208, there's some *lines* in the image at about 60-90sec into the flight. Is that a reflection or what?
Over the years I have talked to some of the engineers on the Photo Analysis working groups about that and similar effects. Believe me you and I are not the first to ask about these. It is a result of a combination of things such as optics and lighting, aerodynamic effects changing the light refraction and so on...the head of the team told me you could probably earn a PhD by studying the phenomenon.
Mark Kirkman
Post by: Chris Bergin on 05/01/2006 02:31 am
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newsartist - 1/5/2006 3:26 AM
How was that airlock moved from the Internal to External configuration?
Even if it came apart, that seems to be a very unwieldy piece of metal to pass through the crew cabin pressure hull!
Post by: UK Shuttle Clan on 05/01/2006 09:59 am
Post by: Jim on 05/01/2006 12:22 pm
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UK Shuttle Clan - 1/5/2006 5:59 AMWe all know how noisey a launch is. How do the astronauts get protected by that incredible noise of the SRBs during ascent when they are just a few hundred feet above those beasts?
The orbiter structural protects them and they are wearing helmets.
Post by: Jim on 05/01/2006 12:25 pm
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newsartist - 1/5/2006 3:26 AMHow was that airlock moved from the Internal to External configuration?Even if it came apart, that seems to be a very unwieldy piece of metal to pass through the crew cabin pressure hull!
It did come apart in pieces and they went out thru the payload bay via the hatch area. It was design to do this.
Post by: Stowbridge on 05/01/2006 02:23 pm
Post by: Tony T. Harris on 05/01/2006 04:57 pm
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UK Shuttle Clan - 1/5/2006 4:59 AM
We all know how noisey a launch is. How do the astronauts get protected by that incredible noise of the SRBs during ascent when they are just a few hundred feet above those beasts?
It also helps that the sound is travelling away from them.
Post by: mkirk on 05/02/2006 05:34 pm
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Tony T. Harris - 1/5/2006 11:57 AMQuoteUK Shuttle Clan - 1/5/2006 4:59 AM
We all know how noisey a launch is. How do the astronauts get protected by that incredible noise of the SRBs during ascent when they are just a few hundred feet above those beasts?
It also helps that the sound is travelling away from them.
On some of the in-cockpit mission tapes I have, the ambient cockpit sounds can be heard quite well. It gets pretty noisy in the transonic region and around Max Q...you really hear the wind out side the cockpit...kind of a howling/whistling sound, and the instrument panels seem to rattle rather loudly. After SRB sep it is very quiet.
So yes the crew is in front of the noise and they are in a sealed cabin with communication caps ("Snoopy" cap) and Helmets on, but it does get pretty noisy in the cockpit.
Unfortunately my only reference is the SMS (shuttle mission simulator) and what crew members have told me. The SMS is semi-realistic with a little "shake, rattle, and roll" and some simulated noise. Crew members say that the real thing is no comparison...
Mark Kirkman
Post by: DaveS on 05/02/2006 06:06 pm
Post by: shuttlefan on 05/02/2006 06:22 pm
Post by: Jim on 05/02/2006 06:46 pm
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DaveS - 2/5/2006 2:06 PMHere's a question regarding the HRSI tiles on the forward part of the OMS pods. Why were they added? On early flights with the orbiters they lacked them, but later they were added. Any specific reason whey they were added?
Turbulent airflow off the chines was striking the pods directly (see STS-1) and was hotter than predicted. It also shredded the AFRSI on STS-6. Also they were taking some debris hits. So the thicker HSRI tiles were added.
Post by: Jim on 05/02/2006 06:47 pm
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shuttlefan - 2/5/2006 2:22 PMDoes a shuttle launch leave behind any kind of a long-lasting smell in the pad area and if so does that smell even reach the press site and viewing areas?
Depends on winds, but there is a smell
Post by: DaveS on 05/02/2006 07:23 pm
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Jim - 2/5/2006 8:46 PMThanks, I suspected it was something like this.
Turbulent airflow off the chines was striking the pods directly (see STS-1) and was hotter than predicted. It also shredded the AFRSI on STS-6. Also they were taking some debris hits. So the thicker HSRI tiles were added.
Post by: GLS on 05/04/2006 10:25 am
Thanks to mkirk for the words on the camera lines!
Post by: shuttlefan on 05/04/2006 02:25 pm
Post by: mkirk on 05/04/2006 02:31 pm
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shuttlefan - 4/5/2006 9:25 AM
I've heard of them changing tiles on the pad. Is that harder to do than in the OPF?
It really depends on the location of the tiles in question. The OPF is by far the best place for tile work since you have the right kind of access and can control the environment easier. Pad work is doable but not desireable.
Mark Kirkman
Post by: Jim on 05/04/2006 03:13 pm
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mkirk - 4/5/2006 10:31 AMQuoteshuttlefan - 4/5/2006 9:25 AMI've heard of them changing tiles on the pad. Is that harder to do than in the OPF?It really depends on the location of the tiles in question. The OPF is by far the best place for tile work since you have the right kind of access and can control the environment easier. Pad work is doable but not desireable.Mark Kirkman
They have used scoffolding and temp platforms to do tile work at the pad. But if it is on the belly between ET, then no access
Post by: Chris Bergin on 05/04/2006 05:39 pm
Post by: psloss on 05/04/2006 05:47 pm
http://www.stsliftoff.com/reference/2001_3417.pdf
Philip Sloss
Post by: PlanetStorm on 05/05/2006 08:27 pm
OK, my submission for "dumbest question of the year" award...
Rather than retiring all the shuttles in 2010, would it be possible to leave one permanently docked to the ISS as a lifeboat?
Post by: Flightstar on 05/05/2006 08:31 pm
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PlanetStorm - 5/5/2006 3:27 PM
OK, my submission for "dumbest question of the year" award...
Rather than retiring all the shuttles in 2010, would it be possible to leave one permanently docked to the ISS as a lifeboat?
The only dumb question is the one that's not asked.
Orbiters can't survive in space for too long. Even if you took away the power requirements, they'd get very ill very fast with the whole enviorment of space.
Post by: DaveS on 05/05/2006 08:35 pm
The shuttle was never intended as a long duration spacecraft like the Soyuz and Progress spacecrafts.
Post by: PlanetStorm on 05/05/2006 08:49 pm
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Flightstar - 5/5/2006 3:31 PM
Orbiters can't survive in space for too long. Even if you took away the power requirements, they'd get very ill very fast with the whole enviorment of space.
Sick orbiter? Would that be the structure/electronics degrading in a radiation environment, or something else?
Post by: PlanetStorm on 05/05/2006 08:50 pm
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DaveS - 5/5/2006 3:35 PM
No. The orbiter uses cryogenic propellants(LH2 and LOX) to power to the three fuel cells and once those die the loses it capability to power it's systems like critical heaters for the OMS and RCS.
The shuttle was never intended as a long duration spacecraft like the Soyuz and Progress spacecrafts.
Not possible to redirect ISS power to the orbiter?
Post by: DaveS on 05/05/2006 09:02 pm
Edit:
Cryogenic fluids boils off so the supplies of LH2 and LOX will decrease even if you power everything off. The orbiter's were simply not designed with a long on-orbit lifetime in mind.
Post by: shuttlefan on 05/08/2006 01:53 pm
Post by: norm103 on 05/08/2006 01:58 pm
Post by: Jamie Young on 05/10/2006 11:08 pm
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DaveS - 5/5/2006 4:02 PM
The orbiter would dead when you undocked it!
Edit:
Cryogenic fluids boils off so the supplies of LH2 and LOX will decrease even if you power everything off. The orbiter's were simply not designed with a long on-orbit lifetime in mind.
Could they replace them with electrical power units?
Post by: Jim on 05/11/2006 12:52 am
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Jamie Young - 10/5/2006 7:08 PMQuoteDaveS - 5/5/2006 4:02 PM The orbiter would dead when you undocked it! Edit: Cryogenic fluids boils off so the supplies of LH2 and LOX will decrease even if you power everything off. The orbiter's were simply not designed with a long on-orbit lifetime in mind.Could they replace them with electrical power units?
What are electrical power units?
also who would fly it home? who would be trained to fly it. Who on the ground would maintain proficency in shuttle systems? How long does it take to power it up. how would the atmosphere be maintained while dormant.
Post by: dmc6960 on 05/11/2006 07:17 pm
Post by: DaveS on 05/11/2006 07:18 pm
Post by: psloss on 05/12/2006 10:33 pm
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psloss - 12/5/2006 2:00 PMThis question -- about the main engine limits switch -- comes out of the 51-F thread in the video section; here's the shuttle reference again, as a reference:QuoteAvron - 5/11/2005 5:31 PMThis would be a good question for the Q & A thread -- particularly that switch...
Thanks... so what they basically took the remaining engines out of Auto shutdown mode, that in itself sounds a little dangerous..."position inhibits all automatic shutdowns". That brings up another question, what then would shut down the engines, time... cannot be velocity, lack of gass, but that would be very bad?
http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/prop/maldet.html
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Although a shutdown as a result of violating operating limits is normally automatic, the flight crew can, if necessary, inhibit an automatic shutdown through the use of the main engine limit shut dn switch on panel C3. The switch has three positions: enable, auto and inhibit. The enable position allows only the first engine that violates operating limits to be shut down automatically. If either of the two remaining engines subsequently violates operating limits, it would be inhibited from automatically shutting down. The inhibit position inhibits all automatic shutdowns.My question is regarding the first call on this after the center engine shutdown, although any explanation of this ascent from the experts would be greatly appreciated. After the center engine shutdown, the crew was told to take the switch to Enable -- this was just after the single engine TAL call. Later on, when one of the two "fuel turbine temp" sensors on the right engine failed (reported in a similar pattern to that of the center engine), the crew was called to take the switch to Inhibit.
Given the description from the reference manual and the situation where you already have one engine out, can someone clarify the difference between Enable and Inhibit? (Or perhaps this logic has changed since 51-F?)
Also, was the call to take the switch to Enable a function of the failure?
Thanks,
Philip Sloss
Post by: mainengine on 05/12/2006 11:33 pm
If you like to read a summary of all former and actual flight engines look at http://www.mainengine.gratis-webspace.de/ssme_engines.html
Post by: mkirk on 05/12/2006 11:51 pm
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psloss - 12/5/2006 5:20 PM
My question is regarding the first call on this after the center engine shutdown, although any explanation of this ascent from the experts would be greatly appreciated. After the center engine shutdown, the crew was told to take the switch to Enable -- this was just after the single engine TAL call. Later on, when one of the two "fuel turbine temp" sensors on the right engine failed (reported in a similar pattern to that of the center engine), the crew was called to take the switch to Inhibit.
Given the description from the reference manual and the situation where you already have one engine out, can someone clarify the difference between Enable and Inhibit? (Or perhaps this logic has changed since 51-F?)
Also, was the call to take the switch to Enable a function of the failure?
Thanks,
Philip Sloss
The Main Engine Limit Shutdown Switch and its operation is relatively complex so I will just hit some of the main points without getting into the nuances of various failure engine failure modes.
There are 5 space shuttle main engine parameters (used to be 6 prior to the block II engines) that are designated as “critical” to engine operation. These “redline limits” are all monitored by the main engine controller mounted directly on the engine. Exceeding one of these limits COULD result in uncontained or catastrophic failure.
If one of the limits is exceeded that engine’s controller will want to shut the engine down. Depending on where in the trajectory the shuttle is, and depending on what abort boundary has been reached at the time of the problem, shutting down the engine may not be a good idea. Dealing with this dilemma is the function of the Main Engine Limit Shutdown Switch.
The switch has three positions:
Enable – Enables the controller to shutdown the SSMEs
Inhibit – Inhibits the controller from shutting down any SSMEs
Auto – Enables the controllers to shutdown one SSME that exceed a redline limit. Limits are then inhibited on the remaining SSMEs. The Auto position can be reset to allow another shutdown by moving the switch to Enable, then back to Auto. This action is called “limits enable / auto” or “re-enabling limits”.
The philosophy of when to re-enable the limit shutdown software attempts to balance the risk of an engine failing catastrophically while the limits are inhibited against the risk associated with a two engine out contingency abort.
In most cases management of the switch will be coordinated by mission control since they have more insight into the health of the engines.
For 51-F when the first engine exceeded it’s redline parameter and based on the limit switch being in Auto (always in Auto at launch), the engine controller shut the engine down and the orbiter’s general purpose computers automatically inhibited the limit software for the remaining to engines. Once an engine fails the crew is trained to expect to re-enable the limit software as soon as possible (i.e. abort capability). This is usually called up to the crew by mission control. Since the first engine failure was actually do to a sensor problem and not a real engine problem, and since the other engines were also in danger of being erroneously shutdown by faulty sensors, and since the shuttle was at an appropriate abort boundary; mission control called up to the crew “Main Engine Limits Inhibit”. This was done to prevent any additional engine shutdowns for bad sensors...if MCC or the crew had noticed a real problem with the engine a manual shutdown still could have been performed.
Mark Kirkman
Post by: psloss on 05/13/2006 12:10 am
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mkirk - 12/5/2006 7:38 PMThanks as always, Mark.
For 51-F when the first engine exceeded it’s redline parameter and based on the limit switch being in Auto (always in Auto at launch), the engine controller shut the engine down and the orbiter’s general purpose computers automatically inhibited the limit software for the remaining to engines. Once an engine fails the crew is trained to expect to re-enable the limit software as soon as possible (i.e. abort capability). This is usually called up to the crew by mission control.
So, just to be clear, the call that CapCom Dick Richards made just after the single engine TAL boundary call "...and main engine limits to enable, Gordo" was the call to re-enable the limits, right?
Philip Sloss
Post by: mkirk on 05/13/2006 12:28 am
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psloss - 12/5/2006 6:57 PMQuotemkirk - 12/5/2006 7:38 PMThanks as always, Mark.
For 51-F when the first engine exceeded it’s redline parameter and based on the limit switch being in Auto (always in Auto at launch), the engine controller shut the engine down and the orbiter’s general purpose computers automatically inhibited the limit software for the remaining to engines. Once an engine fails the crew is trained to expect to re-enable the limit software as soon as possible (i.e. abort capability). This is usually called up to the crew by mission control.
So, just to be clear, the call that CapCom Dick Richards made just after the single engine TAL boundary call "...and main engine limits to enable, Gordo" was the call to re-enable the limits, right?
Philip Sloss
I am on a wireless net so I really can't download the 51-F file until I have a better coverage area early tomorrow. When I anwered your question I went by what you said about the later call to inhibit. So let me double check what was said and when.
What should have happend after the first failure was a call to re-enable...The crew would have cycled the switch to Enable then back to Auto to regain shutdown protection for the remaining engines. As the Booster Console in the MCC (mission control center) evaluated the engine failure they would have tried to protect the remaining engines from an erroneous shutdown. To do this they would have made a call to "Inhibit" once the orbiter achieved an appropriate abort capability.
Mark Kirkman
Post by: mkirk on 05/13/2006 05:46 pm
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psloss - 12/5/2006 6:57 PM
So, just to be clear, the call that CapCom Dick Richards made just after the single engine TAL boundary call "...and main engine limits to enable, Gordo" was the call to re-enable the limits, right?
Philip Sloss
I finally downloaded and listened to the audio…I have never bothered to listen to it before. When I get I chance I will have to get a copy of the whole flight loop and booster loops.
Let me answer your question about the switch.
When the center engine shut down the limits on the remaining two engines were automatically inhibited by the GPCs. You want that to happen because the Orbiter has not yet achieved Single Engine Abort capability and shutting down another engine would have been bad. After passing the “Single Engine TAL” boundary Houston called the crew to “Main Engine Limits to Enable Gordo (Gordon Fulerton)”. This meant if another engine exceeded it redlines it would automatically shutdown leaving the orbiter with one engine to perform a TAL abort.
As “Booster” continued to evaluate the center engine shutdown, she determined it occurred do to a bad sensor for the “Fuel Turbine Temperature”. She also saw that one of the two remaining engines had a similar sensor problem. Because of this she advised Flight to “Inhibit” the limits so the remaining engines would not be shut down by the bad sensors and she would keep an eye on the actual “temperatures”. If at this point either of the other two engines truly exceeded a “Redline Limit”, then she would have advised “Flight” to have the crew manually shut the engine down.
Mark Kirkman
Post by: mkirk on 05/13/2006 05:47 pm
An ATO (abort to orbit) is initiated when ascent performance is not sufficient to achieve orbital velocity without performing an OMS DUMP. This was the case on 51-F when the center engine shut down do to faulty temperature sensor readings.
The crew was told to “Abort ATO”; at that time Gordon Fullerton turned the abort knob on the front instrument panel to ATO and pushed the abort button. When the abort is initiated, the OMS (orbital maneuvering system) engines immediately fired to “Dump” propellant. This is done to reduce the orbiters weight which helps the performance of the remaining main engines and it also provides a small amount of thrust which also helps performance.
The objective of the ATO is to dump just enough of the OMS propellant to ensure MECO (main engine cutoff) for the two remaining engines occurs at “Design Underspeed”.
“Design Underspeed” is defined as the minimal orbit capability (in terms of altitude and velocity) which ensures the orbiter is safe and the External Tank will not land on critical land masses when it re-enters the atmosphere.
Mark Kirkman
Post by: psloss on 05/13/2006 06:02 pm
Also going to pass along some time references for the thread; this is an excerpt from the mission report:
http://members.aol.com/WSNTWOYOU/STS19MR.HTM
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At 5 minutes 43 seconds after lift-off, both temperature readings for the SSME (Space Shuttle Main Engine) 1 high pressure turbopump indicated above the redline, resulting in a premature shutdown of SSME 1 and the declaration of an ATO (abort-to-orbit) condition. This is the first such abort condition encountered during the Shuttle Program. An OMS (orbital maneuvering system) burn was initiated at 210:21:06:06.0 G.m.t., for 106 seconds and used approximately 4134 lb of propellant. At 8 minutes 13 seconds into the flight, one of two temperature sensors on SSME 3 indicated a high temperature reading and auto shutdown for the remaining two engines was inhibited to assure achieving an acceptable orbit. The OMS (orbital maneuvering system)-2 burn placed the Shuttle in a 143.1- by 108.0-nmi. orbit with an inclination of 49.57 degrees.One thing I didn't see in the mission report was when the first sensor reading went over its redline on the center engine, which was earlier in the ascent (if I recall correctly, somewhere around plus 3 and 1/2 minutes)...
Whoops, the other thing that I was looking for was how much of an underspeed they ended up with at MECO...
Philip Sloss
Post by: mkirk on 05/13/2006 06:13 pm
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psloss - 13/5/2006 12:49 PM
One thing I didn't see in the mission report was when the first sensor reading went over its redline on the center engine, which was earlier in the ascent (if I recall correctly, somewhere around plus 3 and 1/2 minutes)...
Whoops, the other thing that I was looking for was how much of an underspeed they ended up with at MECO...
Philip Sloss
I'll have to look that up and also listen to the entire tapes.
FIDO should have called out the underspeed value right around MECO but it is not on this recording.
Also here is a link to main engine stuff. It is slighly dated but far more current than the STS News Reference. Page 26 and 27 discuss the engine limit switch. It also discusses the 6 parameter the controller tracks for redline shutdowns. The new Block II engines only use 5 of them.
http://www.shuttlepresskit.com/scom/216.pdf
Mark Kirkman
Post by: psloss on 05/13/2006 06:32 pm
Quote
mkirk - 13/5/2006 2:00 PMThanks, Mark -- I probably have a copy of that somewhere, but obviously I need to re-read it.
Also here is a link to main engine stuff. It is slighly dated but far more current than the STS News Reference. Page 26 and 27 discuss the engine limit switch. It also discusses the 6 parameter the controller tracks for redline shutdowns. The new Block II engines only use 5 of them.
http://www.shuttlepresskit.com/scom/216.pdf
Mark Kirkman
Philip Sloss
Post by: GLS on 05/18/2006 09:58 am
When you have a SSME lockup (hydraulic or electrical) at, let's say 82% like STS-3 had, is MECO commanded at the same time for all engines, or you shutdown the locked up SSME just, just before the others, to account for it's higher throttle level??
Also, if the 3 engines locked up, would they still go uphill and exceed the 3Gs, or would they shutdown at 3Gs and go ECAL or TAL or whatever?
Post by: mkirk on 05/18/2006 05:56 pm
Quote
GLS - 18/5/2006 4:45 AM
A couple of interesting questions....
When you have a SSME lockup (hydraulic or electrical) at, let's say 82% like STS-3 had, is MECO commanded at the same time for all engines, or you shutdown the locked up SSME just, just before the others, to account for it's higher throttle level??
Also, if the 3 engines locked up, would they still go uphill and exceed the 3Gs, or would they shutdown at 3Gs and go ECAL or TAL or whatever?
There are 2 kinds of “stuck throttles”, an engine can be stuck at full power (104.5% for nominal ascent) or they can be stuck at a lower setting (such as 67% during the throttle down for maximum dynamic pressure). Technically any engine with the throttle stuck below 104.5% is referred to as “stuck in the bucket”.
If you have one or more engines stuck in the bucket then you have a performance problem (i.e. your ability to go uphill is degraded). Depending on the number of engines and type of failure (“Hydraulic/Electrical Lock Up” or “Command Path”) you will likely be in an Abort scenario. Some “Command Path” failures can be fixed with a “restring” of the GPCs (in simple terms this means the General Purpose Computer responsible for the engine is changed).
If the engine(s) is stuck at a high power setting you do not have a performance problem, but a manual shutdown will be required prior to the actual MECO (main engine cutoff). This is more of a problem if two engines are stuck. The reason is the engines will not be able to throttle back during “3G Throttling” which begins about 1 minute prior to MECO. In order to prevent an “Over G” of the orbiter, one of the engines must be shutdown early. The time of the shutdown will be dependent on the type of failure that caused the stuck throttle…typically shutdown will be at MECO minus 2 minutes or at a orbiter velocity > 23,000 feet per second.
Stuck throttles at a lower power setting will increase the MECO time since the rate of propellant consumption has been reduced.
In the case of STS-3 that you mentioned; engine 3 was in a hydraulic lock up condition because of the problem with APU 3. Hydraulic lock means the valves which control power and mixture for an engine are stuck in there last commanded position. On STS-3 the lockup occurred so late in the ascent that it did not pose a significant performance problem.
This is just a basic rundown. There are many other scenarios that can complicate matters.
Mark Kirkman
Post by: Naraht on 05/18/2006 06:00 pm
Quote
mkirk - 13/5/2006 6:33 PMAs I said before in the relevant thread, I would really, really love to hear those if there's any chance of them being posted here.
I finally downloaded and listened to the audio…I have never bothered to listen to it before. When I get I chance I will have to get a copy of the whole flight loop and booster loops.
Post by: zerm on 05/20/2006 03:04 am
Quote
mkirk - 13/5/2006 6:33 PMAs I said before in the relevant thread, I would really, really love to hear those if there's any chance of them being posted here.[/QUOTE]
I finally downloaded and listened to the audio…I have never bothered to listen to it before. When I get I chance I will have to get a copy of the whole flight loop and booster loops.
I'll second that.
And here's my dumb question- perhaps it's been asked and answered, but these Q&A threads are so long, it's hard to tell.
Q: Looking at the SRBs, I've noticed that one has a thick black band at the top, but the other does not. Why is this?...please educate me.
Post by: Jim on 05/20/2006 02:25 pm
Quote
zerm - 19/5/2006 10:51 PMQuotemkirk - 13/5/2006 6:33 PMAs I said before in the relevant thread, I would really, really love to hear those if there's any chance of them being posted here.
I finally downloaded and listened to the audio…I have never bothered to listen to it before. When I get I chance I will have to get a copy of the whole flight loop and booster loops.
I'll second that.
And here's my dumb question- perhaps it's been asked and answered, but these Q&A threads are so long, it's hard to tell.
Q: Looking at the SRBs, I've noticed that one has a thick black band at the top, but the other does not. Why is this?...please educate me.
To tell them apart
Post by: zerm on 05/20/2006 04:27 pm
Is the marking for photo tracking?
Post by: abacus on 05/20/2006 04:38 pm
Post by: Jim on 05/20/2006 06:05 pm
Quote
abacus - 20/5/2006 12:25 PM
It is obvious which one is which when they are connected to the ET, but i assume it allows you to tell them apart after separation and during recovery
That is correct
Post by: zerm on 05/20/2006 06:23 pm
Post by: GLS on 05/21/2006 10:19 pm
Quote
mkirk - 18/5/2006 6:43 PM
In order to prevent an “Over G” of the orbiter, one of the engines must be shutdown early. The time of the shutdown will be dependent on the type of failure that caused the stuck throttle…typically shutdown will be at MECO minus 2 minutes or at a orbiter velocity > 23,000 feet per second.
So on an "Over G" case you shutdown 1 engine early... I thought you would kill the 3 engines (stupid thing to do)! Thanks alot!!!
Post by: wbmiller3 on 05/24/2006 02:02 am
Quote
PlanetStorm - 5/5/2006 3:37 PM
Not possible to redirect ISS power to the orbiter?
Actually this is in work. The SSPTS (Space Station Power Transfer System) will be added to the orbiters Real Soon Now allowing them to draw power from the ISS while docked. This will allow longer docked time.
Unfortunately, there are a lot of other reasons why the orbiter wouldn't make a good lifeboat.
Post by: wbmiller3 on 05/24/2006 02:08 am
Quote
mkirk - 12/5/2006 6:38 PM
For 51-F when the first engine exceeded it’s redline parameter and based on the limit switch being in Auto (always in Auto at launch), the engine controller shut the engine down and the orbiter’s general purpose computers automatically inhibited the limit software for the remaining to engines. Once an engine fails the crew is trained to expect to re-enable the limit software as soon as possible (i.e. abort capability). This is usually called up to the crew by mission control. Since the first engine failure was actually do to a sensor problem and not a real engine problem, and since the other engines were also in danger of being erroneously shutdown by faulty sensors, and since the shuttle was at an appropriate abort boundary; mission control called up to the crew “Main Engine Limits Inhibit”. This was done to prevent any additional engine shutdowns for bad sensors...if MCC or the crew had noticed a real problem with the engine a manual shutdown still could have been performed.
One of the great unsung heroes of the shuttle program, Jenny Howard, was the Booster that day. She realized from the signature on the first engine failure that the turbine discharge temperature ducers were flaking out, and made the call to inhibit limits. The ducers went sour on a second engine after that - this call prevented an unnecessary shutdown and subsequent abort.
Added - I see Mr. Kirkman already answered this, but I left it here as a salute to Ms. Howard.
Post by: psloss on 05/24/2006 11:42 am
Quote
wbmiller3 - 23/5/2006 9:55 PMRoy Bridges said as much back in the 1987 documentary, too. This actually reminds me of another question about what was going on in the MCC during that ascent: did the second fuel turbine temp transducer on the right engine go over the limit prior to MECO?
One of the great unsung heroes of the shuttle program, Jenny Howard, was the Booster that day. She realized from the signature on the first engine failure that the turbine discharge temperature ducers were flaking out, and made the call to inhibit limits. The ducers went sour on a second engine after that - this call prevented an unnecessary shutdown and subsequent abort.
Added - I see Mr. Kirkman already answered this, but I left it here as a salute to Ms. Howard.
Just wondering,
Philip Sloss
Post by: nacnud on 05/24/2006 03:26 pm
IE what are the forces between the ET, SRBs and the Orbiter?
Post by: astrobrian on 05/24/2006 08:40 pm
Post by: Jim on 05/24/2006 09:06 pm
OV 260 1182
ET 1,658 0
SRB 2x 1,300 2x 3,300
The weights and thrust constantly and therefore the loads
At launch the SRB's help lift and accelerate the ET But the OV is always putting in a load of the SSME thrust minus the OV weight into the ET.
Post by: nacnud on 05/24/2006 09:28 pm
Post by: shuttle_buff on 06/01/2006 07:28 pm
After the first 4 shuttle flights (STS-1 thru STS-4), all space suits were eliminated and a casual "jumpsuit" was worn? No helmet, gloves, pressurization or anything. Correct?
After Challenger, the pressurized space suits returned and have been used ever since.
I ask this because I look at old crew photographs after STS-4 and the crew is wearing jumpsuits not space suits.
I know the space suits are removed in orbit but was wondering about STS-5 to STS-twenty something.
Thanks,
shuttle_buff
Post by: Rocket Guy on 06/01/2006 07:32 pm
Post by: Jim on 06/01/2006 07:36 pm
Quote
Ben - 1/6/2006 3:19 PM
They did wear a helmet with their jump suits from 5-51L.
LEH's (launch and entry helmets) and the crew wore standard flight suits with US military type flight boots/
Post by: GLS on 06/02/2006 02:23 pm
And while we're talking about SRBs, does anyone know why the SRBs, on the OV-104 stack that rolled to the pad in October 86 (and the SRB only stack rollout in the summer of 86) http://www.capcomespace.net/dossiers/espace_US/shuttle/1986-95/1986%20octobre%20atlantis%2001.jpg , have the field joints painted black and the factory joints painted white? (all the other SRBs have, or just the factory joints painted black or all joints white)
Post by: shuttlefan on 06/05/2006 02:22 am
Post by: GLS on 06/05/2006 10:56 am
Other tankings (that I'm aware) were 2 tankings on STS-35 due to the LH2 leaks, 4 on STS-38 also due to LH2 leaks, 1 on STS-91 to check the new SLWT and the 2 tankings on STS-114. Not sure but I think the STS-35 and 38 tankings were "mini-tanking" tests, were you don't fill the all the tank. Give me a couple days to search my stuff and I'll have more info....
BTW, anyone wants to take my SRB question?
Post by: shuttlefan on 06/06/2006 01:06 am
Post by: GLS on 06/08/2006 10:38 am
Then came the hot summer of 1990 (or cold due to all the leaking LH2 :) ): 2 mini-tankings on STS-35, the first on 060690 with LH2 loaded to 20%, and the second on 301090 with LH2 loaded to 100% with normal topping and stable replenish. 4 mini-tankings on STS-38, on 290690 with 5% LH2, on 130790 with 50-65% LH2, on 250790 with 10-15%, and on 241090 with 25% LH2. Then they did something on STS-37, an inert leak check or something. I think it had to do with having OV-104 and ET-37 together again (ET-37 was the original tank on STS-38, it did the first 3 mini-tankings).
STS-91 had a tanking test on 180598 to test the first SLWT, and STS-114 had 2, on 140405 and on 200505. Is this enough info for you?
"I thought I read they performed tanking tests even upto and including STS-9-I may be wrong."
Don't know because on the web, NASA has (in my opinion) little info about the early missions...., but I think the WCDTs were only a part of OFT missions.
Post by: shuttlefan on 06/08/2006 01:59 pm
Post by: shuttlefan on 06/09/2006 04:00 am
Post by: Jim on 06/09/2006 04:13 am
Post by: GLS on 06/09/2006 01:27 pm
Post by: mkirk on 06/10/2006 12:15 am
Quote
shuttlefan - 8/6/2006 10:47 PM
Would it be possible for NASA to ignite the OMS engines on the pad and let them run for 20 seconds just like they did with the SSMEs several times in earlier shuttle years, though I do realize there is no test objective that would require this... :)
GLS’ post is correct there is an altitude restriction for the OMS (orbital maneuvering system) engines. They are not ignited below 70,000 feet primarily because of aero-thermal concerns. The worry is that the engine bells would collapse.
I don’t believe there is any altitude constraint for the RCS (reaction control system) jets. However, the first time they are used is right at SRB SEP (solid rocket booster separation) to help protect the orbiter windows from debris/residue by deflecting the plume produced by the separation motors. The last time they are used during a mission is when the orbiter slows below MACH 1 (which is ususally at 50,000 to 55,000 feet) prior to landing.
Interestingly, with regard to Pad test firings, the RCS thrusters on the Gemini capsule were test fired late in the countdown after the crew had been strapped into their seats and the service structure had been retracted.
Mark Kirkman
Post by: shuttlefan on 06/11/2006 06:56 pm
Post by: Justin Space on 06/12/2006 04:11 pm
Post by: Chris Bergin on 06/12/2006 06:20 pm
Quote
Justin Space - 12/6/2006 4:58 PM
How long does it take for the exhaust to clear the pad after launch? Is that cloudof smoke hazardous?
I believe there is hazardous gas involved and it takes three days for it to be safe. Someone will be able to confirm that.
Post by: mkirk on 06/12/2006 07:46 pm
Pad access after launch is controlled by the NASA Test Director. About 10 minutes after launch the initial Pad Safing Teams are dispatched. The areas around the Pad are inspected and within about an hour the FSS and MLP are inspected. FOD (foreign object debris) walk downs are conducted and by about 3 hours 15 minutes after Launch the Pad is declared open.
In fact they usually let the Media/Photographers in the Pad area within hours of Launch so they can retrieve their remote cameras.
My theory on that is NASA is letting those guys (photographers) serve as human “canaries” like they use in coal mines. If a photographer keels over then the NASA Test Director knows it is not safe to let people he likes into the Pad area. :)
Mark Kirkman
Post by: Launch Fan on 06/12/2006 09:52 pm
Quote
mkirk - 12/6/2006 2:33 PM
My theory on that is NASA is letting those guys (photographers) serve as human “canaries” like they use in coal mines. If a photographer keels over then the NASA Test Director knows it is not safe to let people he likes into the Pad area. :)
Classic!
Post by: astrobrian on 06/12/2006 10:19 pm
If I remember correctly the stuff is very acidic too
Post by: mkirk on 06/12/2006 10:29 pm
Quote
Launch Fan - 12/6/2006 4:39 PMQuotemkirk - 12/6/2006 2:33 PM
My theory on that is NASA is letting those guys (photographers) serve as human “canaries” like they use in coal mines. If a photographer keels over then the NASA Test Director knows it is not safe to let people he likes into the Pad area. :)
Classic!
Quote
astrobrian - 12/6/2006 5:06 PM
So wrong yet so funny.
If I remember correctly the stuff is very acidic too
I guess I should point out that as part of my cosulting work I am one of those photographers/canaries...as is Ben
Mark Kirkman
Post by: astrobrian on 06/12/2006 10:41 pm
Post by: Rocket Guy on 06/12/2006 10:51 pm
SRB exhaust consists mainly of of hydrohcholic acid (very corrosive to things like cameras (!), in liquid (dissolved in water) and gas forms); aluminum oxide (white residue that gets all over everything); and nitrogen dioxide (the smelly gas in the air, toxic in concentrated amounts). There's more stuff (because the fuel has polymers as well keeping it together) but that is what results from the burning of the fuel portion.
Post by: astrobrian on 06/12/2006 10:52 pm
Post by: Rocket Guy on 06/13/2006 12:02 am
The HCl and A2O3 residue that covers things sometimes feels as though it burns a little, but that may be placebo :-) I sometimes bring gloves if I remember. Of course, for the Shuttle there isn't much of it. But on ELVs where we can put our cameras under the SRB if we wanted to it's a different story.
I wish I had some photos but apparently not.
Post by: zinfab on 06/14/2006 09:27 pm
Q- What is the maximum duration a space shuttle SHOULD be able to remain in LEO (attached or not attached to the ISS) with enough fuel/power to return to earth? A range will be fine--I know different configs/aborts/etc. affect this.
Post by: astrobrian on 06/15/2006 01:40 am
Quote
zinfab - 14/6/2006 4:14 PM I have finally read all 50 pages of this (and the first) Q&A thread. Wow. Thanks so much to all of you. I've been a NASA junkie for years and this is the first in-depth source of information I've ever found. Glad you're all here! It's like drinking from a fire hose! This is, by far, the most intelligent forum of discussion I've ever visited.
That was my assesment when I stumbled into this lair :) welcome to the site
As for your question on shuttle duration. I know there have been missions of 14 days in length. Someone here will be able to get more specific than that though.
Post by: Jim on 06/15/2006 01:45 am
Std 10 +2 contingency
EDO 18 + 2
SSPTS 21 +2
Post by: zinfab on 06/15/2006 01:59 am
Post by: zinfab on 06/15/2006 01:47 pm
Post by: GLS on 06/23/2006 01:29 pm
Post by: Jim on 06/23/2006 01:49 pm
Post by: shuttlefan on 06/24/2006 12:57 am
Post by: astrobrian on 06/24/2006 01:00 am
Post by: shuttlefan on 06/24/2006 01:04 am
Post by: mkirk on 06/25/2006 05:03 pm
Quote
shuttlefan - 23/6/2006 7:51 PM
I read that in the pre-Challenger days, the astronauts didn't bother learning too much about the SRBs because they couldn't control them anyway and did that change after Challenger? ;)
That is still more or less the case. Astronauts get some basic system overview briefings for the SRBs and a rundown of how they are prepared/loaded with propellant at ATK and then shipped to and processed at the Kennedy Space Center.
Astronauts are also given briefings on the sensitive subject of the Range Safety System. The external tanks no longer fly with such a system because it really isn’t necessary but the SRBs still have it for obvious reasons.
During flight training sessions in the SMS (shuttle mission simulator) there is very little exposure to SRB related problems. Some problems such as a stuck nozzle actuator or burn performance issues (i.e. the SRBs can burn slightly hotter or cooler than expected) are really the only cases presented during training but that is really all the crew can deal with.
The SRBs simply have to work every time!
Mark Kirkman
Post by: rfoshaug on 06/28/2006 10:56 am
1. For a mission to ISS, the ascent phase must of course be timed so that the orbital plane of ISS passes over the launch site at the time of launch (or probably a few seconds/minutes before launch to give the shuttle some time to accelerate - but how much?). But once the shuttle is in orbit, there's bound to be some deviation between shuttle orbit and ISS orbit. This deviation must be compensated for by orbital plane adjustments using the OMS engines. I'm quite satisfied if I get below 1 degree difference between my orbit and that of the ISS. How large a deviation is normal in real shuttle operations?
2. When, or more specifically, where does the de-orbit burn start? How many miles/kilometers from the landing site? For example for a return to KSC from the orbital plane of ISS - where does the burn start?
3. What is the altitude at the point of the de-orbit burn? I usually place the orbiter in a 200-to-250-kilometer circular orbit before the de-orbit burn instead of de-orbiting directly from ISS altitude. Is this how it's done on the real orbiters?
4. How long is the burn? I read somewhere 2.5 minutes, but what determines the length of the burn and the delta-v? Is it to place the calculated impact point (assuming no atmosphere and assuming that the perigee of the orbit is placed below the surface) at a specific place, or is it to place the perigee at a specific altitude?
5. How much (percentage) OMS fuel is usually in the tanks at various flight stages such as ISS docking, start of de-orbit burn and after landing?
If anyone knows this stuff, any answers would be highly appreciated. :)
Post by: Jim on 06/28/2006 12:48 pm
Post by: Jamie Young on 06/29/2006 02:26 am
Was it based on the biggest satellite it was hoped it would launch?
Post by: Jim on 06/29/2006 02:47 am
It was build it and they will come wrt 60 x 15.
Post by: GLS on 06/29/2006 09:02 am
Quote
rfoshaug - 28/6/2006 11:43 AM
I've got a couple of questions about the ascent and descent phases of space shuttle missions. I've been trying to fly some shuttle missions in Orbiter (www.orbitersim.com - excellent sim BTW) and want to do it as realistically as possible.
1. For a mission to ISS, the ascent phase must of course be timed so that the orbital plane of ISS passes over the launch site at the time of launch (or probably a few seconds/minutes before launch to give the shuttle some time to accelerate - but how much?). But once the shuttle is in orbit, there's bound to be some deviation between shuttle orbit and ISS orbit. This deviation must be compensated for by orbital plane adjustments using the OMS engines. I'm quite satisfied if I get below 1 degree difference between my orbit and that of the ISS. How large a deviation is normal in real shuttle operations?
2. When, or more specifically, where does the de-orbit burn start? How many miles/kilometers from the landing site? For example for a return to KSC from the orbital plane of ISS - where does the burn start?
3. What is the altitude at the point of the de-orbit burn? I usually place the orbiter in a 200-to-250-kilometer circular orbit before the de-orbit burn instead of de-orbiting directly from ISS altitude. Is this how it's done on the real orbiters?
4. How long is the burn? I read somewhere 2.5 minutes, but what determines the length of the burn and the delta-v? Is it to place the calculated impact point (assuming no atmosphere and assuming that the perigee of the orbit is placed below the surface) at a specific place, or is it to place the perigee at a specific altitude?
5. How much (percentage) OMS fuel is usually in the tanks at various flight stages such as ISS docking, start of de-orbit burn and after landing?
If anyone knows this stuff, any answers would be highly appreciated. :)
Yes, Orbiter rocks!
This are generic anwsers. In the end, it all depends on vehicle mass, propelants, ISS alt., etc........
1) It's probaly better than 0.01ş
2) More or less on the other side of the world...
3) From the ISS, you deorbit from an altitude around 200nm (370Km).
4) On deorbit burn you want do dip your perigee into the atmosphere. How much depends on your altitude and the range/crossrange to the landing site. After the deorbit burn your perigee would be around 15-30nm (27-54Km). How long you burn depends on you mass. 150 seconds is tipical, but some missions burned for 120 seconds and others for 300 seconds.
5) It depends on the mission, but I think you cannot have more than 22% (or is it 26%???) on landing.
Post by: Jim on 06/29/2006 11:53 am
Post by: GLS on 06/30/2006 08:21 am
Quote
Jim - 29/6/2006 12:40 PM
for #4, for the real shuttle, the perigee intersects with the earth's surface after deorbit burn.
That was for the real shuttle! Does that happen on all the flights??? I only have info on very few flights... I could be *incomplete*...
Post by: Jim on 06/30/2006 11:51 am
Quote
GLS - 30/6/2006 4:08 AMQuoteJim - 29/6/2006 12:40 PM
for #4, for the real shuttle, the perigee intersects with the earth's surface after deorbit burn.
That was for the real shuttle! Does that happen on all the flights??? I only have info on very few flights... I could be *incomplete*...
Yes.
I couldn't find deorbit burn files but the files massprop, shows the diffence in weight between deorbit burn and entry interface. Most of the delta is the OMS burn, but there is wieght loss due to RCS firings and the APU's running.
The other file has OMS-1 and -2 burn data
Post by: MKremer on 06/30/2006 11:47 pm
The booster separation motors in the attached image look to have some pretty large environmental seals/covers on them. Are they removed before launch, and if so, when?
If they're left on, how much mass does each have, and how are they discarded when separation occurs (ie- whereabouts do they travel when they pop off as the motors fire?)
Post by: Jamie Young on 07/01/2006 03:01 am
Post by: Jim on 07/01/2006 01:38 pm
Quote
Jamie Young - 30/6/2006 10:48 PM
Don't the bolts fire, booster comes off, then it fires the motors a second later? By then the orbiters out of the way?
Same time
Those covers have hinges and swing way, like barn doors
Post by: Rocket Guy on 07/01/2006 03:46 pm
Post by: Jonesy STS on 07/01/2006 07:24 pm
Quote
Ben - 1/7/2006 10:33 AM
The bolts release 1/1000th second before they ignite.
Isn't that the hold down bolts, not the bolts that cover the top end nose cone trusters?
Post by: Rocket Guy on 07/01/2006 07:31 pm
Post by: Launch Fan on 07/01/2006 11:04 pm
Post by: Jim on 07/02/2006 02:33 am
Quote
Launch Fan - 1/7/2006 6:51 PM
I saw that there was venting out of the top of the tank, Liquid Oxygen, but why was there venting out of the bottom of Discovery near her SSMEs? I thought only Liquid Oxygen had boil off, or am I totally wrong?
they are purging and conditioning the engines to cool them down so that there is not cryogenic shock
Post by: Chris Bergin on 07/02/2006 05:13 pm
As I like to say, "No, it's damn rock!" :)
Post by: Chris Bergin on 07/03/2006 08:27 am
I'll contact you by e-mail or PM.
Quote
Robert A.M. Stephens - 3/7/2006 2:10 AM
(Trivia: What was the first words John Young said on air, publicly, to the world after he raced down off the orbiter, right after landing and safing of the bird to a point him and Crippen could egress, at the end of STS-1?)
Robert
Damn, this has got me, as I can only recall the "Would you like me to park her in the Hanger" "I think we'll dust her down first" comments, on rollout down the runway." plus the "She's the world's greatest electric flying machine".
I bet Ben E knows :)
Post by: astrobrian on 07/03/2006 12:20 pm
Post by: Jim on 07/03/2006 01:21 pm
Quote
astrobrian - 3/7/2006 8:07 AM
I was looking at some of the older mission patches and realized they don't put the orbiters name on them hardly at all anymore. why not?
There weren't that many orbiters at the time, now a mission might switch orbiters
Post by: EVA on 07/03/2006 02:15 pm
Quote
Chris Bergin - 3/7/2006 3:14 AM
Thanks Robert -
I'll contact you by e-mail or PM.QuoteRobert A.M. Stephens - 3/7/2006 2:10 AM
(Trivia: What was the first words John Young said on air, publicly, to the world after he raced down off the orbiter, right after landing and safing of the bird to a point him and Crippen could egress, at the end of STS-1?)
Robert
Damn, this has got me, as I can only recall the "Would you like me to park her in the Hanger" "I think we'll dust her down first" comments, on rollout down the runway." plus the "She's the world's greatest electric flying machine".
I bet Ben E knows :)
When I first read the question, the traditional aviation phrase said after the first flight of an airplane, first said after the the first flight of the B-17, "We've got a winner!", came to mind, but after reading Chris' reply, I think he's on the right track, wasn't it something like "Dust her off and put her in the hangar."?......I dunno.
Post by: Duff on 07/03/2006 04:50 pm
I would first of all like to thank the moderators and the people who post here for such a great site.
Ok,
The Crawler Transporter ( CT ), carrying the Mobile Launch Platform (MLP) and the shuttle stack has just made its long walk from the Vehicle Assembly Building (VAB) to the launch pad.
Once there:
1) how long does it take to get the MLP in the right spot?
2) is there a area marked where it must go, or is it lined up using lasers?
3) how accurate must it be or is there a allowance for it be so far out of square or in line?
4) if the MLP is out of square, can the CT spin with the tracks in opposite directions to square it self up or does it have to walk back a bit and line up better?
5) are the hard stands there already in place or they put under MLP with a forklift?
6) is the MLP bolted and torqued to the hard stands ( and the hard stands to the pad ) or is it just free standing and will not move due to the weight of the whole structure?
7) how long does it take to have the MLP ready for launch ( on the hard stands, hydrogen and oxygen lines connected, noise suppression water lines connected, electrical harnesses connected and everything else that I have not included)?
Much appreciated for any answers
Duff
Post by: selden on 07/03/2006 05:01 pm
Quote
wasn't it something like "Dust her off and put her in the hangar."?
According to SpaceMad on this Forum's own Quotes page, it was
Quote
"Do you want me to park her in the hanger?" - "I think we'll dust her down first!" Young and Houston talking after landing Columbia on STS-1
note: this is in response to EVA, not the trivia question.
This doesn't sound like something you'd say after you've left the orbiter.
Post by: Jim on 07/03/2006 07:56 pm
Quote
Duff - 3/7/2006 12:37 PM
Hello everyone
I would first of all like to thank the moderators and the people who post here for such a great site.
Ok,
The Crawler Transporter ( CT ), carrying the Mobile Launch Platform (MLP) and the shuttle stack has just made its long walk from the Vehicle Assembly Building (VAB) to the launch pad.
Once there:
1) how long does it take to get the MLP in the right spot?
2) is there a area marked where it must go, or is it lined up using lasers?
3) how accurate must it be or is there a allowance for it be so far out of square or in line?
4) if the MLP is out of square, can the CT spin with the tracks in opposite directions to square it self up or does it have to walk back a bit and line up better?
5) are the hard stands there already in place or they put under MLP with a forklift?
6) is the MLP bolted and torqued to the hard stands ( and the hard stands to the pad ) or is it just free standing and will not move due to the weight of the whole structure?
7) how long does it take to have the MLP ready for launch ( on the hard stands, hydrogen and oxygen lines connected, noise suppression water lines connected, electrical harnesses connected and everything else that I have not included)?
Much appreciated for any answers
Duff
they use lasers and sights.
there are supports already in place.
Post by: Jim on 07/04/2006 04:18 pm
Quote
Nick L. - 4/7/2006 10:54 AM
What is the purpose of the AstroVan vehicle? Is there some sort of contamination hazard that the AstroVan helps to avoid?
Nick
Just a mode of transportation that has the size for 7 crew members and other support personel and extra cooling for the crew and cooloinghook ups for their suits
Post by: zinfab on 07/06/2006 12:41 am
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=3149&posts=10&start=1
nuchem - 5/7/2006 12:13 AM
Quote
1. When propellant is pumped out of the tanks the tank pressure will drop. Low pressure could cause cavitations of the propellant and implosion of the tank. How does one avoid this pressure drop? Has it never posed a problem? I can think of numerous ways to solve it I wonder what’s been done in practice.
buckwheat wrote:
Quote
The shuttle's ET is pressurized by an "autogenous" pressurization system. This means that the tanks are pressurized by some of the propellant they are carrying, during flight. Here's how this works. As the engines pull in propellant during flight, a small bit is tapped off and run through a heat exchanger. This converts the LOX or LH2 into gas. This gas is then sent up, via the GO2 and GH2 presslines, to its respective tank. The gas enters the upper part of the tank ullage (ullage = gas space in a propellant tank, as opposed to the liquid space) through a diffuser, which evenly spreads the pressurant gas throughout the upper part of each tank.
The flow of these pressurant gases on the Space Shuttle is slightly different between the LH2 and LOX tanks. Initially, both systems used "Active Flow Control Valves" (located just downstream of the SSMEs, inside the Orbiter) which controlled the flow of pressurant gases exiting the SSME heat exchangers. The valves would remain open when the tank pressure went below a certain set point (in the case of LH2, the set point is 32.5 psia) and open when the pressure went above a certain set point (for LH2, this is 33.5 psia). FCV from SSME #1 is tied directly to the pressure of LH2 tank pressure transducer #1, FCV #2 to XDCR #2, and so forth with #3. Incidentally, when the valve is "closed" a low flow of GH2 flows through it, and when it is "open" a high flow passes through it.
Starting with STS-40, the LOX tank has been pressurized with a "Fixed Orifice Pressurization System". Basically, there were so many failure modes associated with these Flow Control Valves (such as valves sticking open - whether due to valve failure or transducer drop-out during flight) that it was decided to try a system that used a fixed flow orifice, and no valves, and after careful analysis and testing (the four flights between STS-35 and STS-39 used "shimmed" valves that zeroed in on the 78% size eventually chosen) the correct size was found, and that is still in use today. This gives the LOX tank pressure profile a very noticeable flight profile, complete with a "slump" initially and an "overshoot" later in flight. The LOX tank pressure transducers read pressure in "psid", which differs from PSIG slightly (since the ducers are located in the ET nosecap compartment, the "d" is the differential pressure between the NC compartment and ambient). The range is from about 13 psid during the "slump" about 10-15 seconds into flight, to about 25 psid around T+250 seconds. The ICD limits on LOX tank ullage pressure are pretty generous, allowing this range - the only bottleneck apparently occurs during Max-Q (65-80 sec or so) when stress requirements on the tank narrow the range considerably.
This system has worked just about flawlessly for the Shuttle ET since STS-1.
Incidentally, because of stress and NPSP requirements with the LH2 tank, a similar Fixed Orifice system could not be implemented there... however, a few years ago (STS-97?) a "shimmed" orifice system was implemented for the LH2 tank, which significantly reduced the number of FCV cycles during flight. This also greatly lessened the risk of a tank overpressurization during flight (GH2 venting during flight is considered, since STS-51L, a CRIT-1 failure) and also helped on the low side, reducing the chances that the "Astronaut Logic" specified in the Shuttle Flight Rules would need to be used (and protecting against NPSP dropout - i.e., cavitation).
Hope this helps. Probably more than you wanted to know, I used to work with one of these systems and still remember it well.
Post by: darkenfast on 07/06/2006 02:59 am
Post by: astrobrian on 07/06/2006 03:05 am
Post by: darkenfast on 07/06/2006 09:04 am
Post by: kneecaps on 07/06/2006 10:41 am
(ORB PKT, PRIOR PWRDN)
I know that the section in brackets refers to a checklist however I don't know what checklist the ORB PKT is , any ideas?
A quickie for somebody in the know!
Thanks
Pete
Post by: British NASA on 07/06/2006 01:27 pm
Quote
Robert A.M. Stephens - 6/7/2006 1:48 AM
Question: what did John Young say right after the STS-1 landing about the STS?
Answer:
He walked hurriedly around the orbiter for an initial looksee, as Crippen was also egressing, then up to the mic, and said;
"Hail, Columbia."
Then he turned slightly, pointing at the orbiter, still looking at the attending crowd (an me) and said, "That is one incredible flying machine."
Quite a moment and my first assignment for the agency for documenting STS and other space related endeavors, then and now. I always remembered that line since it was so profound and so out of character for the otherwise very cool John Young, a very gutsy man indeed. I documented STS-1 for launch and then out to EAFB for the landing.
Robert
That's awesome! :)
Post by: Jim on 07/06/2006 03:37 pm
Quote
kneecaps - 6/7/2006 6:28 AM
In the timelines they refer to a PRIORITY PWRUP GRP B B
(ORB PKT, PRIOR PWRDN)
I know that the section in brackets refers to a checklist however I don't know what checklist the ORB PKT is , any ideas?
A quickie for somebody in the know!
Thanks
Pete
Orbiter Pocket Checklist
Post by: mkirk on 07/06/2006 09:59 pm
Quote
Jim - 6/7/2006 10:24 AMQuotekneecaps - 6/7/2006 6:28 AM
In the timelines they refer to a PRIORITY PWRUP GRP B B
(ORB PKT, PRIOR PWRDN)
I know that the section in brackets refers to a checklist however I don't know what checklist the ORB PKT is , any ideas?
A quickie for somebody in the know!
Thanks
Pete
Orbiter Pocket Checklist
The Pocket Checklists are primarily for “Non Nominal Procedures” that require time critical responses. Time critical is defined as procedures requiring a response in 5 minutes or less. There are three Pocket Checklists called Ascent, Entry and Orbit.
The Group B Priority Powerdown is contained in the Orbit Pocket Checklists however the use of the powerdown in this case is a routine procedure and not a reaction to a malfunction.
The lettered powerdowns (A, B and C) are designed for mission specific operations while the numbered powerdowns (1,2,3 etc.) are for contingencies. Each powerdown procedure is designed to either decrease the electrical or thermal load by shutting down systems in an orderly and efficient manner.
In this particular case the Group B Powerdown helps reduce the load on the fuel cells and in turn the amount of cryogenics (oxygen & hydrogen) consumed so that the mission can potentially be extended to support the 3rd EVA. Group B reduces electrical load by turning off none essential lighting, flight displays, CRTs/MFD (multifunction displays), heaters, MDMs (multiplexer demultiplexers) and other non essential equipment.
Mark Kirkman
Post by: Chris Bergin on 07/07/2006 05:34 am
Quote
Zoomer30 - 7/7/2006 4:52 AM
A few times in Shuttle history at the moment of SRB ignition you will see a BIG cloud form behind the shuttle stack, as tall as the ET. Seems like a shockwave cloud. Anyone know of a flgiht where this happened. I think it must happen when the temp and dewpoint are very close together (ie, very humid day)
Post by: GLS on 07/09/2006 03:54 pm
Recently, STS-104 had alot of this... on SRB ignition, as it clears the tower and until about 50 sec or so... A few others are STS-96, STS-32R, STS-82, STS-86, STS-24, STS-25, etc....
Post by: shuttlefan on 07/09/2006 05:08 pm
Post by: DwightM on 07/09/2006 06:15 pm
Post by: Zoomer30 on 07/09/2006 09:33 pm
Post by: Zoomer30 on 07/09/2006 09:36 pm
Post by: Naraht on 07/09/2006 10:06 pm
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shuttlefan - 9/7/2006 5:55 PM
Can someone tell me: On what Shuttle flight prior to Challenger/51-L, did they experience the worst o-ring erosion on an SRB field joint?
I've taken a browse through Diane Vaughan's book on Challenger, and I think that STS-2 would have had the most erosion of an O-ring on an SRB field joint. (0.053"). 51-C (the launch at very low temperature) had some erosion, but it was really the blow-by that was of concern on that flight. 51-B had the most serious erosion but that was on a nozzle joint rather than a field joint.
Post by: ruthsarian on 07/11/2006 03:43 pm
If there was a serious problem with the SRBs immediately after liftoff is it at all possible to do an SRB sep at low altitude and would the SSME have enough thrust to keep the shuttle up long enough to return safely? I know the SSMEs provide a low percentage of the total thrust used to get the shuttle up (23% is it?) but the SRB weight is more than half of the total stack's weight, so would the SSMEs be enough without the SRB weight? This is ignoring the fact that the SRBs would need to be destroyed immediately to keep them from crashing into populated areas.
The RSS units on the SRBs and ET are connected so if one receives an arm/fire signal it's passed to all three units. Is this a physical connection? Meaning if the SRBs are separated and only one receives the signal, will only the one SRB destruct or does it pass that signal on? And is the arm/fire signal for the RSS units the same signal for all three or can the RSO target which receives the signal? So in the event of the senario given above, could the RSO destroy the SRBs without triggering the ET RSS unit?
How much education/discussion is there with the astronauts about RSSs, how the RSO makes his/her decision, and what the worst-case scenarios are? Is it something that you just don't really talk about?
I don't mean to be morbid if this comes off as such. It's just that these are aspects of the shuttle you never hear much about.
Post by: Jim on 07/11/2006 03:52 pm
The Astronauts are aware of the system and how the decision is made. Of course they know the worst-case scenario (only one): the shuttle is sent the destruct command. And yes, it something that you just don't really talk about
One last point for every one. RSO no longer exists, it is the MFCO (missile flight control officer)
Post by: NASA_Twix_JSC on 07/11/2006 03:58 pm
Post by: Gary on 07/11/2006 04:44 pm
Quote
Jim - 11/7/2006 4:39 PM
The SRB/ET joint only allows disengagement one way: ET up -SRB down. The SRB plume would burn the shuttle. Not enough thrust. I think the ET RSS was removed (see other threads). The SRB are cross linked and independent. One command does all
The Astronauts are aware of the system and how the decision is made. Of course they know the worst-case scenario (only one): the shuttle is sent the destruct command. And yes, it something that you just don't really talk about
One last point for every one. RSO no longer exists, it is the MFCO (missile flight control officer)
There is quite an in depth explanation of the Range Saftey System both pre and post Challenger in Mike Mullanes 'Riding Rockets' book.
In there he does mention that the ordanance package was removed from the ET post Challenger.
Thanks for a fascinating thread and I know this is repeating what others have said but this really is the most informative website for any space-related so thanks to everyone for that.
Post by: elmarko on 07/17/2006 03:46 pm
HATCH OPENING (ELS)
Before hatch opening:
Tabs/Visor - CL
Green Apple - PULL
Firstly, what is ELS? And secondly, what the heck is the Green Apple? :)
Post by: Jim on 07/17/2006 03:50 pm
Green apple is the emergency O2 valve.
Post by: elmarko on 07/17/2006 03:53 pm
Post by: Jim on 07/17/2006 03:56 pm
Quote
elmarko - 17/7/2006 11:40 AM
Aha, thanks. Do you have any idea why it is so named? It's shape or appearance?
Both. It is an Air Force term
Post by: mkirk on 07/17/2006 07:13 pm
Quote
elmarko - 17/7/2006 10:33 AM
From the Entry Checklist:
HATCH OPENING (ELS)
Before hatch opening:
Tabs/Visor - CL
Green Apple - PULL
Firstly, what is ELS? And secondly, what the heck is the Green Apple? :)
Jim is right the Green Apple (sometimes called the "granny apple") is the handle that is used to activate the Emergency O2 for the Pressure Suit. Below is a picture of Reiter taken during egress training at JSC, you can see the little green ball on his right side.
ELS stands for emergency landing site. Procedures are written differently depending on where the orbiter lands. The primary landing sites (Kennedy, Edwards, Northrup) have more ground support than a TAL site would have and the TAL sites have more support than an emergency landing site or a contingecy landing site. In this procedure you listed here, it tells you to activate the O2 because at the ELS there may not be any equipment to detect a potentially hazardous leak from the OMS/RCS thrusters or the APUs...so when you open the hatch at the ELS you automatically assume there is a leak and activate the O2.
Mark Kirkman
Post by: TheMadCap on 07/17/2006 09:49 pm
Quote
NASA_Twix_JSC - 11/7/2006 10:45 AM
If, pretend, there was such a seperation, because they are still going at full thrust, they wouldn't happily drop away, they'd go forward and in various uncontrolled directions. Most likely roasting those on board as they destroy the orbiter and tank. No option.
I believe you would also get a massive deceleration of the remaining stack, leading to destructive aerodynamic forces on the orbiter. In addition to being burned up, of course...
Post by: elmarko on 07/18/2006 08:58 am
One further question if I may:
When landing at an Emergency Landing Site, what happens to comms? Do they have the frequencies for the approach/tower of all the ELSs? Or is accepted that they will just use 243.000 and hope there's a nice person on the other end monitoring? Or, as a third option, I guess NASA would relay this information ahead and the airport would be.. er... expecting them? :)
Post by: MKremer on 07/18/2006 09:01 am
Post by: elmarko on 07/18/2006 11:09 am
Post by: Jim on 07/18/2006 12:51 pm
Quote
elmarko - 18/7/2006 6:56 AM
Even the ECALs and the extreme emergency sites? (IE, not TAL sites, but the ones that are listed as being backups in a just in case type of thing :)
the Shuttle uses UHF
Post by: elmarko on 07/18/2006 01:23 pm
Post by: Jim on 07/18/2006 02:03 pm
Quote
elmarko - 18/7/2006 9:10 AM
I know, my point was, what frequency would they use for communication? Stick it on Guard (243.000) or stay on 259.7? Do they even need to talk to the emergency landing site, or do they just carry on talking to Houston?
They don't talk the landing site now, why would a change be required. Houston handles it
Post by: mkirk on 07/18/2006 10:40 pm
When the Shuttle lands anywhere on the globe. the LSO (Landing Support Officer) in the Mission Control Center is respondible for coordinating with them...this could involve a whole bunch of different people and agencies such as the FAA, ATC (air traffic control), State Department, NASA forward personnel, quick response agencies and so on.
The crew also has a hand held PRC-112 radio for rescue operations and to talk with the Landing Convoy after landing.
Mark Kirkman
Post by: elmarko on 07/19/2006 09:09 am
Is that radio used after landing at a "normal" landing site or just for aborts/emergencies/whatever?
And speaking of the LSO, i would assume his/her job would be made much harder if it was a landing on foreign soil, with all the coordination with their local agencies. All that bureaucracy and red tape... heh.
Post by: Jim on 07/19/2006 11:29 am
Quote
elmarko - 19/7/2006 4:56 AM
Thanks for the replies everyone, very interesting :) I just had a look at that handheld radio on the web, it looks like it's specifically for rescue ops, given that it has all the guard frequencies and 282 (which I'm guessing should be 282.8, which from my memory I believe is allocated to NATO scene and search for SAR ops).
Is that radio used after landing at a "normal" landing site or just for aborts/emergencies/whatever?
And speaking of the LSO, i would assume his/her job would be made much harder if it was a landing on foreign soil, with all the coordination with their local agencies. All that bureaucracy and red tape... heh.
the orbiter UHF is used on the ground. Handheld is only for contigencies.
It would be an extreme small probabilty that the orbiter would land at a site where there isn't a NASA rep at. If not, there would be some time to plan for it.
There is a NASA rep at the TAL sites that handles most of the work load. There is also DDMS who help.
The LSO has a back room to handle stuff like this. It just wouldn't be hem
Post by: Bruce H on 07/19/2006 06:46 pm
Quote
norm103 - 19/7/2006 1:25 PM
if the shuttle would land at the capes sikd stip cold it just be towed over to the opf or would they have to mate it to the sac?
?? Can't understand your writing, use a spellchecker to help.
Post by: Jim on 07/19/2006 06:56 pm
Post by: ruthsarian on 07/19/2006 08:51 pm
In this picture there's a red-colored shell of some sort around the large nozzle on the OMS pod. Is there any particular reason why these are covered like that and the SSME nozzles are not? And at what point in the processing of the orbiter are they removed?
This picture shows an inside view of the SSME nozzle. This image provides the same view but there's a cover over the MCC. Is that just for protection or does it serve another purpose? At what point is it removed before flight?
Thanks
Post by: DaveS on 07/19/2006 08:58 pm
Post by: HKS on 07/19/2006 08:59 pm
And what makes this difference?
Post by: Jim on 07/19/2006 09:17 pm
Quote
ruthsarian - 19/7/2006 4:38 PM
I've seen people on here talk about an "ascent assist" where OMS engines are fired during ascent and that the primary purpose for this is to dump excess weight in the form of fuel. People have also said that OMS engines provide relatively little thrust. If that's the case, why carry that much fuel to begin with?
In this picture there's a red-colored shell of some sort around the large nozzle on the OMS pod. Is there any particular reason why these are covered like that and the SSME nozzles are not? And at what point in the processing of the orbiter are they removed?
This picture shows an inside view of the SSME nozzle. This image provides the same view but there's a cover over the MCC. Is that just for protection or does it serve another purpose? At what point is it removed before flight?
Thanks
Here is my take on OMS assist. (MKirk will correct me if I am off)
There are many reasons. But to sum it up, full tanks is a easier starting point from ground ops and flight analysis prospectives.
They are all protective covers. The OMS engines are more fragile than the SSME's They are removed in the countdown.
Post by: mkirk on 07/20/2006 12:47 am
Since I can’t go back and edit it, here is how the entire post should have read:
Some of the discussions on other threads about OMS Burns make me want to clarify some things about the De-Orbit Burn.
Tomorrow at about 8:07 eastern time Discovery will fire both OMS engines from a heads down, tail forward, wings level position (pitch will be adjusted as needed prior to the burn - usually +/- 20 degrees). The burn will last for 3 minutes and 2 seconds and will decrease Discovery’s orbital velocity by 302 feet per second (or about 206 statute miles per hour). These numbers will be adjusted slightly tomorrow as the burn targets are more finely tuned by Mission Control. The numbers are also slightly different for each landing opportunity.
The objective of the De-Orbit Burn is to decrease the orbital velocity and in turn decrease the perigee (lowest point) of the orbit. The resulting orbit will be highly elliptical and the path of the orbit is designed such that Discovery will be at an altitude of 400,000 feet at a range from the landing sight of 4449 nautical miles. I never really paid attention to the perigee on the De-Orbit Maneuver Display since I was more interested in other parameters such as time to entry interface, and burn residuals/errors…but I believe that most of the time the perigee of the orbit after the burn is between 5-25 nautical miles. So considering that Discovery will have an apogee (highest point of in the orbit) of around 185 miles, you can see just how elliptical the resulting orbit is.
Anyway my point is the De-Orbit Burn targets a point we call Entry Interface (EI) which is defined as 400,000 feet at a specified range from the runway, in this case 4449 nm for tomorrow’s first opportunity to KSC (for the second opportunity EI occurs at 4375 nm).
For you orbital mechanics experts, the computers refer to the range parameter to EI as Theta T. Theta T is the angle formed by a line drawn from the center of the earth to the OMS engine ignition point and a line drawn from the center of the earth to the orbiter's EI point…I believe this angle is around 160 degrees or so. Theta T is not defined this way for Ascent OMS Burns, but I won’t get into that here.
On average the time from OMS ignition to EI is approximately 30-35 minutes.
Mark Kirkman
Post by: Jim on 07/20/2006 05:48 pm
If there was an ET schedule published on a other thread, please point me to it
Post by: Chris Bergin on 07/20/2006 09:22 pm
Quote
Jim - 20/7/2006 6:35 PM
I have a question. Of the remaining ET's required for the flyout, how many are structurally complete, those only that only require foam and instrumentation etc.
If there was an ET schedule published on a other thread, please point me to it
This is a first, answering a question for Jim! :)
From L2 MAF ET manifest status:
"ET-123 in now over in Cell A at MAF.
ET-124 is next and will replace ET-123 in Cell A when shipped.
ET-117 is in holding ready - after returning from KSC - ready to enter the flow.
"Our plate is filling up," said deputy ET project manager Mark Bryant (MAF/Lockheed)."
So up to ET-117 is a tank structure. ET-120 is a tank proper, as is ET-93, but were used as test articles...so will need some serious work.
The rest of the tanks are likely to be just a LOX tank here, an intertank there.
That's the last I heard from MAF, but will ask again for an update.
Post by: Mark Dave on 07/21/2006 08:32 pm
What about the SRBs? How's the status of those going?
Post by: mkirk on 07/21/2006 08:43 pm
Quote
MarkD - 21/7/2006 3:19 PM
I was wondering on launch day you hear "GLS is go...". Is there an operator for the GLS? I ask because usually I heard the GLS is automatic computer only. *shrugs*
What about the SRBs? How's the status of those going?
Yes there is a console operator position for the GLS (called CGLS), he/she ensures the GLS software is configured properly and executing the required tasks. This is a very critical postion for PAD Aborts.
The GLS console will annuciate a Go/No Go indication at the various countdown milestones and that is what you are normally hearing. Ex: "GLS is go for ET LO2 Pressurization."
Mark Kirkman
Post by: dds121 on 07/24/2006 04:50 am
Post by: norm103 on 07/24/2006 05:52 am
Post by: shuttlefan on 07/27/2006 01:40 pm
Post by: Jim on 07/27/2006 01:51 pm
The whole crew cabin is "gutted" after each mission (most of it at landing and remainder in the OPF in the following days). This allows access to the avionics bay and other systems. "Flight Crew Equipment" is handled by specific organizations at JSC and KSC. Most of the items are prepacked at JSC and shipped to KSC for installation. The cabin is temp setup for TCDT and then removed. The final setup is in the last week before launch.
Post by: shuttlefan on 07/27/2006 02:02 pm
Post by: Austin on 07/27/2006 11:13 pm
Post by: Chris Bergin on 07/27/2006 11:17 pm
Quote
Austin - 28/7/2006 12:00 AM
I have a question about the shuttle's computers. I know that there are a total of 5 onboard computers -- four primary and the other redunant which moniters the health of the other four. But I've always wondered why NASA has continued with the same computers which, if I am correct, are essentially 70's technology. Does the adage "If it ain't broke don't fix it" apply here?
I'd say you've got it right. The "they are old" gets overplayed a lot, because they do the job. Ironically, on the last two flights, what computers have they had problems with? The fancy new Window's driven laptops! :)
Post by: Austin on 07/27/2006 11:25 pm
Quote
Chris Bergin - 27/7/2006 4:04 PMQuoteAustin - 28/7/2006 12:00 AM
I have a question about the shuttle's computers. I know that there are a total of 5 onboard computers -- four primary and the other redunant which moniters the health of the other four. But I've always wondered why NASA has continued with the same computers which, if I am correct, are essentially 70's technology. Does the adage "If it ain't broke don't fix it" apply here?
I'd say you've got it right. The "they are old" gets overplayed a lot, because they do the job. Ironically, on the last two flights, what computers have they had problems with? The fancy new Window's driven laptops! :)
Gotcha. Muchas gracias, Chris!
Post by: Rocket Guy on 07/28/2006 01:33 am
Think about this (as I shared on another forum yesterday)...It was 50 years ago Tuesday night that the Stockholm collided with the Andrea Doria. The heavily-damaged-in-1956 Stockholm is still sailing cruises out of Europe under a different name. It set sail on a cruise to Morocco just two weeks ago!
Post by: Jim on 07/28/2006 02:18 am
Quote
Austin - 27/7/2006 7:00 PM
I have a question about the shuttle's computers. I know that there are a total of 5 onboard computers -- four primary and the other redunant which moniters the health of the other four. But I've always wondered why NASA has continued with the same computers which, if I am correct, are essentially 70's technology. Does the adage "If it ain't broke don't fix it" apply here?
They were replaced with B-1 bomber computers in the late 80's. Same architecture, but it combined two boxes into one. This allowed easier logistics since the B-1 computer would be supported for a longer timeframe.
Changing the computers would have a big impact on the shuttle program.
1. finding a computer that fits into the existing avionics architecture
2. rewriting all the code in a newer language
3 rewriting the backup software into a newer but different code
4. Validating the system
5. Updating the systems at KSC and JSC that interface with the orbiters and the GPC (software and maybe hardware mods) and validationing the upgrades
6. cutting in the new system into the orbiter, simulators, etc
Number 6 is the real problem. How do you do that and still support flying missions. Both types of computers would have to be supported. There would need to be two of everything, except there is only 1 fixed base and 1 motion base simulators, one SAIL, two KSC firing rooms would have to be different along with 2 JSC MOCR's
Actually, the 4 computers watch themselves and if two get voted out ( 2 separate failures) and the two have a disagreement, the 5th takes over with a different software.
Post by: Austin on 07/28/2006 02:55 am
Quote
Jim - 27/7/2006 7:05 PM
They were replaced with B-1 bomber computers in the late 80's. Same architecture, but it combined two boxes into one. This allowed easier logistics since the B-1 computer would be supported for a longer timeframe.
I never knew that they were replaced with B-1 bomber computers -- fascinating.
Quote
Changing the computers would have a big impact on the shuttle program.
6. cutting in the new system into the orbiter, simulators, etc
Number 6 is the real problem. How do you do that and still support flying missions. Both types of computers would have to be supported. There would need to be two of everything, except there is only 1 fixed base and 1 motion base simulators, one SAIL, two KSC firing rooms would have to be different along with 2 JSC MOCR's
What about installing new computers in phases say, during the orbiters' OMPD (Orbiter Major Modification period) rather than all at once?
Post by: astrobrian on 07/28/2006 02:58 am
You would still have to support both types of code and hardware regardless as you cant just ground the fleet and upgrade them all at once. So you'd still be encountering the two of everything
Using code A and code B as examples. Atlantis would be on code A and Discovery on code B after refit. You would have to either have a MCC that supported both codes A and B, or you would have to have two MCC each set up for one or the other. Hopefully that helps
Post by: Austin on 07/28/2006 03:54 am
Post by: elmarko on 07/29/2006 11:54 am
Quote
Chris Bergin - 28/7/2006 12:04 AM
Ironically, on the last two flights, what computers have they had problems with? The fancy new Window's driven laptops! :)
While I appreciate this is probably meant as a joke, I think you can agree that the two configurations are totally different, and you absolutely cannot make a comparison in reliability between something designed for one purpose, and a multi-purpose setup like a standard home PC :P
Still funny though!
Post by: j2_ on 07/31/2006 05:58 pm
Now, I do have a couple of questions about the Attitude Timeline, and flying the shuttle.
I've been playing with the truly amazing (and free!) Orbiter spaceflight simulator on and off for the past year or so. I'm hardly an expert, but I can launch a shuttle, rendezvous and dock with the ISS. I haven't tried a manual re-entry yet, but watching the autopilot fly the reentry is fascinating.
Anyways, here are the questions:
1) Why are the OMS rockets not aligned with the X axis of the orbiter? I believe they are tilted up (+Z i believe) about 15 degrees? I learned in Orbiter that most burns are done prograde. Does this mean the orbiter has to orient itself slightly pitched up with respect to the velocity vector when doing OMS burns?
2) Why does NASA launch the shuttle so far away from the ISS in orbit? It takes two days for the orbiter to catch the ISS from a lower altitude orbit. I know that in the Orbiter sim, if I time my launch correctly, I can rendezvous with the station within about 2.5 hours after launch.
And finally, my real question:
3) I want to fly the shuttle missions as realistically as possible in Orbiter. I've been trying to figure out how to perform all the OMS burns such as NC1, NCC, TI, etc. by looking at the Attitude Timeline from STS-121. I'm having trouble interpreting the attitude I should place my simulated shuttle in for the various OMS burns indicated in the timeline. I see that the delta V is indicated in the timeline as well, but how do I know how to burn my OMS engines for? Can I use my velocity readout on the Orbit MFD to time my OMS burns? (Of course converting from meters/sec to feet/sec) Or is there another instrument I should be looking at?
I can't wait to run my own simulation of the upcoming STS-115 mission, and I want to make sure I do all the OMS burns as realistically as possible!
Thanks
Post by: Jim on 07/31/2006 06:46 pm
2. OMS fuel and they don't want to approach the ISS at a rate where a lot of thrusting is required, to minimize plume impengment. Also they need to check out the orbiter and put it into the on orbit configuration.
3. The timeline burn numbers are for reference. The actuals are provide by MCC before each burn, including TIG and duration of burn. the delta V is not cumulative and not related to orbital speed.
Post by: DaveS on 07/31/2006 08:07 pm
Post by: elmarko on 08/01/2006 12:38 pm
Quote
Jim - 31/7/2006 7:33 PM
1. The OMS are aligned with the thrust vector going through the CG of the orbiter. If they were aligned with the x-axis, the orbiter would pitch down everytime the OMS burn
In Orbiter the craft pitches down when you fire the OMS engines, because of the 13 degree offset. Is this the wrong behaviour? Should the offset mean that the pitch down is cancelled out?
Post by: Jim on 08/01/2006 12:45 pm
PS this isn't an Orbiter Qand A thread.
Post by: mkirk on 08/01/2006 08:41 pm
As an example the OMS trim angles for the Deorbit Burn are usually Pitch 0.0, Left Yaw -5.7, Right Yaw +5.7. These OMS gimbal angles combined with the orbiters attitude during the burn enusre that the desired result is achieved.
OMS burns come in two basic forms, those using targets designed to get the orbiter to a specific spot in space (defined by such parameters as altitude, slope, delta V etc) and targets which are desinged to change the orbital velocity (i.e. add or subtract energy from the current orbit).
Mark Kirkman
Post by: elmarko on 08/02/2006 01:54 am
Quote
Jim - 1/8/2006 1:32 PM
the shuttle orbiter, the OMS engines gimbal to put the thrust vector thru the CG. They are moved to the proper position before each burn. Don't know if this feature is allowed in Orbiter
PS this isn't an Orbiter Qand A thread.
I am well aware it is not an Orbiter Q and A thread, but I don't see any problem with comparing things if it helps to understand the way the real Orbiter works...
Post by: zinfab on 08/02/2006 01:59 am
Post by: j2_ on 08/02/2006 02:03 am
The diagrams you posted were really helpful. An illustration of the orbiter's CG explains it all.
Thanks
Post by: spaceshuttle on 08/05/2006 05:49 am
1. how many OTV cameras are there total?
2. how come OTVs 170/070 are used more than OTVs 171/071?
3. will the shuttles be back on 39a for anymore launches?
4. where is the launch sound recording system device recorder, whatever, located?
5. where can i obtain sound recordings of launches without the launch commentary?
6. does anyone know the coodinates/geographical info on OTVs 071/171 and 070/170
7. during rollover, the SSMEs look worn, kind of like galvanized steel, but later they'll appear black/charcoal grey with the coolant tubes and the bottom edge sometimes being a vivid silver (see an sts-107 SSME replacement picture vs. the ssme close-up at launch, for example)
8. anyone know the names of the launch commentators?
Post by: norm103 on 08/05/2006 06:35 am
this may hlep
Post by: HKS on 08/05/2006 11:06 am
Most of the shuttle cargo is installed at the pad from the RSS, while the shuttle is standing vertical, but I read that some cargo is installed in the shuttle while it is in the OPF, what kind of cargo is it that needs to be installed in the OPF?
Post by: Jim on 08/05/2006 02:34 pm
Quote
spaceshuttle - 5/8/2006 1:36 AM
okay, several questions.
1. how many OTV cameras are there total?
2. how come OTVs 170/070 are used more than OTVs 171/071?
3. will the shuttles be back on 39a for anymore launches?
4. where is the launch sound recording system device recorder, whatever, located?
5. where can i obtain sound recordings of launches without the launch commentary?
6. does anyone know the coodinates/geographical info on OTVs 071/171 and 070/170
7. during rollover, the SSMEs look worn, kind of like galvanized steel, but later they'll appear black/charcoal grey with the coolant tubes and the bottom edge sometimes being a vivid silver (see an sts-107 SSME replacement picture vs. the ssme close-up at launch, for example)
8. anyone know the names of the launch commentators?
1. The previous diagrams should them at the pads, but they are in the VAB, OPF, SSPF, O&C and other KSC facilities.
2. director's chouce
3. Yes, see other threads
4. on the incline to the pad
5. doubt it
6. see diagrams
7. Different cameras
8. George Diller, Bruce Buckingham,
Post by: Jim on 08/05/2006 02:38 pm
Quote
HKS - 5/8/2006 6:53 AM
I have a question:
Most of the shuttle cargo is installed at the pad from the RSS, while the shuttle is standing vertical, but I read that some cargo is installed in the shuttle while it is in the OPF, what kind of cargo is it that needs to be installed in the OPF?
Not any of the future ISS parts are horizontal
Historically, Spacelab Modules, SIR,Spacelab pallets and some SPACEHAB module missions, mostly the sortie type payloads
Post by: psloss on 08/05/2006 02:55 pm
Quote
spaceshuttle - 5/8/2006 1:36 AMIf you're referring to the TV broadcasts of launch attempts, and in particular "watching" SSME start, then it helps to be familiar with the surface winds on that day. There's often an Easterly sea breeze (and in the summer, usually) which will tend to push the engine exhaust into the 071/171 camera. So that's a likely influence on which camera of the two is zoomed in on the engines and which one has a wide shot at the time of ignition.
2. how come OTVs 170/070 are used more than OTVs 171/071?
Edit: looking at some launch video, it may mostly be that the 070/170 position is more likely to have an unobscured view of the engines from start through liftoff, even in a light wind.
Post by: HKS on 08/05/2006 05:30 pm
Quote
Jim - 5/8/2006 4:25 PMSo the SpaceHab Single Modules (S/HAB-SM) for STS-116 and STS-118 will be installed horizontal?QuoteHKS - 5/8/2006 6:53 AM
I have a question:
Most of the shuttle cargo is installed at the pad from the RSS, while the shuttle is standing vertical, but I read that some cargo is installed in the shuttle while it is in the OPF, what kind of cargo is it that needs to be installed in the OPF?
Not any of the future ISS parts are horizontal
Historically, Spacelab Modules, SIR,Spacelab pallets and some SPACEHAB module missions, mostly the sortie type payloads
Post by: Jim on 08/05/2006 07:58 pm
Post by: STSFan10 on 08/08/2006 03:13 pm
Post by: spaceshuttle on 08/08/2006 08:40 pm
Quote
STSFan10 - 8/8/2006 10:00 AM
Logged on to say that I really appreciate these two big Q and A threads. Real eye opener.
heck, i thought insideKSC forums were great. this here is f-ing AWESOME!
Post by: norm103 on 08/12/2006 05:49 am
Post by: DaveS on 08/12/2006 06:57 am
Quote
Jim - 5/8/2006 9:45 PMYep. SpaceHAB RDM, FREESTAR and the EDO cryokit were installed into the payload bay while the orbiter was in the OPF.
I meant the early ones. Since STS-76, they went vertical. Have to check on STS-107, it might have gone horizontal
Post by: MKremer on 08/12/2006 06:59 am
Post by: norm103 on 08/12/2006 08:36 am
Post by: MKremer on 08/12/2006 09:31 am
Post by: kneecaps on 08/14/2006 11:03 am
Flightplan ---> Orbiter chosen ---> Flight Readiness Review ----> MMT Approval ----> Launch
I know most of that is probably way off the mark, but thats the sort of outline i'm looking for (and also how do PRCB proceedings affect missions).
Thanks
Pete
Post by: Jim on 08/14/2006 03:54 pm
Here is a short summary of the processes of putting a shuttle flight together:
1. NASA HQ (with the ISS program) determines what payloads are to fly on the shuttle. A multi-center organization, the Flight Assignment Working Group, takes these payloads and using other requirements (flight rates, orbiter down times, etc) and produces a planning manifest with the payloads on specific orbiters.
2. Once a payload is on the manifest, NASA JSC puts together a MIP/PIP (Mission Integration Plan/Payload Integration Plan). This document covers all the requirements for the payload, includes an ICD and defines verification tests, power, thermal, crew time needs etc. Before this document is baselined and accepted by the shuttle program, it will go before the PRCB for approval.
3. Two to three years before launch, the mission is added to the FDRD (FDRD) Flight Definition and Requirements Document. The PRCB approves the addition of the flight to the FDRD. The FDRD formally documents the Orbiter, ET, SRB, and SSME assignments to this mission. Additionally, landing sites, orbit, EVA’s, crew size, payloads, mission duration, cryo tanks set, RMS, DTO/DSO’s are defined. (The FDRD is just a table of info). Once a mission is in the FDRD, the shuttle program has a go ahead to “build” the mission.
4. The information in the FDRD is further defined in a FRD (Flight Requirements Document). It takes all the requirements from the payloads (MIP’s/PIP’s) and other flight hardware, FDRD, DTO’s, adds Placards/Constraints/Limitations and expands and further defines all the info. Before this document is baselined and accepted by the shuttle program, it will go before the PRCB for approval.
5. After the FRD is baseline, all the flight “production” can start. The Flight plan is developed, software updates created, all the analyses are performed (thermal, loads, acoustic, power, etc), crew training, payload bay configuration, etc.
6. About year before launch a Cargo Integration Review is held. This is to make sure all the integration is meeting the requirements and will support the mission and schedule.
7. Further, down the road a launch site readiness review is held. This is to make sure KSC has all the requirements and docs to start process hardware for a mission.
8. Incremental readiness reviews are held as hardware approaches certain milestones, such as rollover, rollout, ET/SRB mate, payload ground ops, payload to pad, etc.
9. The program holds an FRR. I believe that the MMT takes over at this point
10. The last review is the L-2 review.
Post by: kneecaps on 08/15/2006 07:39 am
Also how many FRRs are there (and by which department/office)?
I used to think there was only one FRR, but its clear that there are several, ie: the MOD FRR and the FRR coming up soon (KSC FRR perhaps?)?
Thanks!
Post by: Jim on 08/15/2006 12:12 pm
KSC's pre FRR used to be call a LRR. The range also has an LRR
I don't know which orgs have "pre FRR's"
Post by: dutch courage on 08/15/2006 03:43 pm
Post by: Jim on 08/15/2006 03:59 pm
Post by: ruthsarian on 08/16/2006 02:01 pm
If not the SRB bolts, when are those installed?
Post by: Jim on 08/16/2006 02:34 pm
Post by: GLS on 08/21/2006 04:55 pm
Post by: mkirk on 08/21/2006 05:03 pm
Quote
GLS - 21/8/2006 11:42 AM
If you stop at T-31 seconds, you can resume the countdown or you can recycle to T-20 minutes. But what happens if you find a problem at T-4 hours, do you count to the next BIH, do you count do T-20 minutes or do you stop there??? Can someone explain me *all* the options (or what can happen) during the countdown. Thanks!
In the case of an issue at around T-4 hours, it would depend on the nature of the problem. The general rule is that you procede to the next Built in Hold for all issues from the start of the Countdown at T-43 hours until T-9 minutes. For problems after T-9 minutes you stop at the next GLS milestone.
Mark Kirkman
Post by: GLS on 08/21/2006 05:23 pm
But, what can happen in terms or recycles and scrubs. Let's say you have that problem at T-4 hours, the count would go down to T-3 hours, as you said. And then can you recycle to T-6 hours (for a 24 hour scrub/turnaround), or do you have to go to T-20 minutes. This seems to be a extensive subject, and I probably won't be happy until I kidnapp an expert on this, but I thank anyone that's willing to help me just a bit.
Post by: Jim on 08/21/2006 05:34 pm
Post by: mkirk on 08/21/2006 05:41 pm
Quote
GLS - 21/8/2006 12:10 PM
Thanks, mkirk!
But, what can happen in terms or recycles and scrubs. Let's say you have that problem at T-4 hours, the count would go down to T-3 hours, as you said. And then can you recycle to T-6 hours (for a 24 hour scrub/turnaround), or do you have to go to T-20 minutes. This seems to be a extensive subject, and I probably won't be happy until I kidnapp an expert on this, but I thank anyone that's willing to help me just a bit.
Well for a problem in that time frame if a scrub is called it would depend on how long a scrub we are talking about. A 24 hour would likely result in a recyle to T-6 hours and that would be the trunaround entry point. If the scrub is longer and lets say they have to service the PRSD then a recycle to T-11 would likely result (this facilitates RSS and OMBUU positioning).
There is also an extended hold option at T-6 hours for problems that occur prior to cryo tanking.
The scrub turnaround procedures are contained in volume 3 of the S0007 (countdown) document. There are 3 basic sub procedures; initial scrub turnaround (to get you in the correct and safe posture), 24 hour, and 48 hour/or extended (the extended is designed for up to 96 hours). Each scrub option ahas re-entry points such as T-11 hours and T-6 hours where you would return to the standard countdown procedures for that point in volume 2 of the S0007 document (volume 2 is the countdown control sequence).
It is a little more complex than that but this gives you the basic idea.
Mark Kirkman
Post by: GLS on 08/21/2006 06:10 pm
Quote
mkirk - 21/8/2006 6:28 PM
The scrub turnaround procedures are contained in volume 3 of the S0007 (countdown) document.
I've to get me one of those...
Post by: kneecaps on 08/22/2006 01:01 pm
Quote
GLS - 21/8/2006 6:57 PM
Thanks mkirk, you filled some of the blanks in my knowledge. But not all.... if you scrub after T-20 minutes, you must recycle back to there before you go on to 24H/48H/whatever turnarounds, right? Other thing, if you stop at T-31 seconds you can recycle to T-20 minutes and then resume the count and try again (well not on the ISS flights.... but that's besides the point). But if you pass T-31 seconds you can't "try again", right? And if you scrub after T-31 seconds (I think it's called cutoff) is it the same as scrubbing before?Quotemkirk - 21/8/2006 6:28 PM
The scrub turnaround procedures are contained in volume 3 of the S0007 (countdown) document.
I've to get me one of those...
Sadly..I've tried to get my hands on a S0007 many times..I'm told its ITAR.
Post by: mkirk on 08/22/2006 10:37 pm
Quote
kneecaps - 22/8/2006 7:48 AM
Sadly..I've tried to get my hands on a S0007 many times..I'm told its ITAR.
To the best of my knowledge that is not true. Volume 5/6 which has contingency actions might be sensitive but the other volumes are not.
Mark Kirkman
Post by: mkirk on 08/22/2006 10:43 pm
Quote
GLS - 21/8/2006 12:57 PM
Thanks mkirk, you filled some of the blanks in my knowledge. But not all.... if you scrub after T-20 minutes, you must recycle back to there before you go on to 24H/48H/whatever turnarounds, right? Other thing, if you stop at T-31 seconds you can recycle to T-20 minutes and then resume the count and try again (well not on the ISS flights.... but that's besides the point). But if you pass T-31 seconds you can't "try again", right? And if you scrub after T-31 seconds (I think it's called cutoff) is it the same as scrubbing before?
If you pass T-31 seconds only cutoff is available and you are done for the day. The recycle to T-20 minutes serves as the staring point for whatever scrub option is chosen. This allows all the safing activities to be accomplished as well as the transitioning of the GPCs (general purpose computers) out of OPS101 and back into G9. OPS101 is the terminal count configuration and G9 is the ground operations/processing config.
Mark Kirkman
Post by: spaceshuttle on 08/24/2006 09:47 pm
they say that the freon was removed from the tanks STARTING with mission sts-87 (last mission of 1997). now, from what i understood in the beginning was that the non-freon foam would start off as a yellow color.
nonetheless,
sts-85 (left) and sts-86's (right) tanks (both before sts-87) started off a beige color, a color you NEVER see at any time on the tanks now-a-days
http://i2.photobucket.com/albums/y48/jjlucash/85.jpg http://i2.photobucket.com/albums/y48/jjlucash/86.jpg
sts-87 was beige
http://i2.photobucket.com/albums/y48/jjlucash/87.jpg
and so was 89 (the mission RIGHT after 87)
http://i2.photobucket.com/albums/y48/jjlucash/89.jpg
but both 87 (left) & 89 (right) darkened to a flat light-brown color...
http://i2.photobucket.com/albums/y48/jjlucash/KSC-97EC-1700.jpg http://i2.photobucket.com/albums/y48/jjlucash/KSC-98EC-0198.jpg
from what i know, today we use the same foam as sts-87, but here on 90, the foam is bright yellow(left)--a common sighting these days--darkening down to the usual gold-tinted color(right)
http://i2.photobucket.com/albums/y48/jjlucash/90.jpg http://i2.photobucket.com/albums/y48/jjlucash/KSC-98EC-0500.jpg
BUT, before 85, the tanks (evidently) began as a tan/light brown, as seen here on 84 (left) and 82 (right)
http://i2.photobucket.com/albums/y48/jjlucash/84.jpg http://i2.photobucket.com/albums/y48/jjlucash/82.jpg
ALSO darkening to a brownish/rusty color
(84 left, 82 right)
http://i2.photobucket.com/albums/y48/jjlucash/KSC-97EC-0788.jpg http://i2.photobucket.com/albums/y48/jjlucash/KSC-97EC-0266.jpg
what's going on with all these changes in the foam formula?
Post by: Jim on 08/24/2006 09:50 pm
Edit:
The first photos were taken at arrival at the pad and the latter photos were of launches or near launch day. The shuttle was outside longer in the latter photos
Post by: Jim on 08/24/2006 09:57 pm
Edit:
you deleted the post that this one refers to
Post by: spaceshuttle on 08/24/2006 10:06 pm
Quote
Jim - 24/8/2006 4:44 PM
When you "saw" the tanks, did they all have the exact same exposure to UV?
Edit:
you deleted the post that this one refers to
i know, the pix were a bit confusing. the earlier pictures in the post were from initial roll-out. the concern wasn't so much as the overall exposure to the UV rays, but to the color of the foam BEFORE any 'lengthy' exposure to the UV rays. from 84-nearly the beginning, the foam was a saddle tan at rollout; from 85-89, the foam was beige/gold at rollout (mind you, they switched to the freon-free foam on sts-87 which was right before 89); and from 90 on to today, the foam is yellow at rollout (with the exception of 114, 121, and 115 as those tanks are OLD and the foam darkens also with age)...
Post by: spaceshuttle on 08/24/2006 11:27 pm
Quote
spaceshuttle - 24/8/2006 4:53 PMQuoteJim - 24/8/2006 4:44 PM
When you "saw" the tanks, did they all have the exact same exposure to UV?
Edit:
you deleted the post that this one refers to
i know, the pix were a bit confusing. the earlier pictures in the post were from initial roll-out. the concern wasn't so much as the overall exposure to the UV rays, but to the color of the foam BEFORE any 'lengthy' exposure to the UV rays. from 84-nearly the beginning, the foam was a saddle tan at rollout; from 85-89, the foam was beige/gold at rollout (mind you, they switched to the freon-free foam on sts-87 which was right before 89); and from 90 on to today, the foam is yellow at rollout (with the exception of 114, 121, and 115 as those tanks are OLD and the foam darkens also with age)...
what i meant was--were there any more foam changes, or is the color difference (85-89 versus 90+) simply due to the change in cameras?
Post by: norm103 on 08/25/2006 05:58 pm
Post by: Jim on 08/25/2006 06:04 pm
Post by: spaceshuttle on 08/25/2006 07:48 pm
Quote
Jim - 24/8/2006 4:37 PM
Also unless the same cameras and the same film and the same paper and the same lighting conditions are used (same goes for digital cameras and software), you are going to get different tints of same color.
i see! it took a little photo editing on powerpoint to see it.
for 89, the tank was probably exposed to the sun (even before VAB assembly or shuttle rollout) and for 90, it was lighter outside and the tank possible had had lest time in the sun prior to rollout.
(see link)
http://i2.photobucket.com/albums/y48/jjlucash/edits1.jpg
and 87, 90, AND 95 tanks ended the same color (see link)
http://i2.photobucket.com/albums/y48/jjlucash/edits2.jpg
it's the overall sanding of the intertank that threw me off. pretty neat!
Post by: spaceshuttle on 08/29/2006 06:39 pm
121 and 115's tanks didn't appear to darken very much while on the pad. does the age of the foam affect the rate at which the foam darkens?
Post by: MKremer on 08/29/2006 07:23 pm
Post by: TheMadCap on 08/30/2006 02:44 am
Post by: shuttlefan on 09/01/2006 02:14 am
Post by: Jim on 09/01/2006 02:23 am
Post by: Chris Bergin on 09/01/2006 12:07 pm
Quote
Coca Cola Cowboy - 1/9/2006 8:45 AM
Hi
I had this dream/nightmare last night about Atlantis. At liftoff of STS-115 one of her main engines didn't start (or malfunctioned directly after liftoff). In the dream, Atlantis wasn't able to make a controlled flight anymore and came dangerously off course. Eventually she smashed into the ground with the SRB's and ET still attached to the vehicle.
A horrible dream of course and my question is, what would really happen if one of the main engines failed during lift-off? Is there a possible escape sequence to be followed so that the Shuttle can make an emergency landing? Or, can the Shuttle in fact still reach orbit with only two of her three engines?
/CCC
Post by: Jim on 09/01/2006 12:13 pm
Post by: astrobrian on 09/01/2006 01:42 pm
Post by: shuttlefan on 09/01/2006 02:01 pm
Quote
Jim - 31/8/2006 9:10 PM
The techs are assigned to "shops" defined by areas of the shuttle. Fwd, Midbody, Aft, TPS, Flight Crew systems, etc. They work on all orbiters. SSME is handled by Rocketdyne. An SSME installation would have Rocketdyne positioning the SSME and USA attaching it.
Thanks for the great answer, as always, Jim!! :)
Post by: shuttlefan on 09/01/2006 02:06 pm
Quote
Chris Bergin - 1/9/2006 6:54 AM
Copied into here.QuoteCoca Cola Cowboy - 1/9/2006 8:45 AM
Hi
I had this dream/nightmare last night about Atlantis. At liftoff of STS-115 one of her main engines didn't start (or malfunctioned directly after liftoff). In the dream, Atlantis wasn't able to make a controlled flight anymore and came dangerously off course. Eventually she smashed into the ground with the SRB's and ET still attached to the vehicle.
A horrible dream of course and my question is, what would really happen if one of the main engines failed during lift-off? Is there a possible escape sequence to be followed so that the Shuttle can make an emergency landing? Or, can the Shuttle in fact still reach orbit with only two of her three engines?
/CCC
That IS a terrible dream!! The loss of just one engine just after liftoff or during the rest of SRB burn would result in an RTLS. I believe one engine out on launch does NOT necessarily mean loss of crew and vehicle.
I think I read one time, many years ago, that there is a very slim chance of all three engines flaming out at SRB ignition. Does anyone know, could this be a direct result of SRB ignition- have any engineering studies revealed this concern?
Post by: dutch courage on 09/01/2006 03:47 pm
Quote
shuttlefan - 1/9/2006 3:53 PM
I think I read one time, many years ago, that there is a very slim chance of all three engines flaming out at SRB ignition. Does anyone know, could this be a direct result of SRB ignition- have any engineering studies revealed this concern?
The exhaust from the solids is very much shielded from the orbiter's main engines also the flame-trench is divided, one side for the orbiter's main engines and one side for the solids.
So the chance of a flame-out to me is very remote.
Post by: astrobrian on 09/01/2006 04:11 pm
Post by: spaceshuttle on 09/01/2006 05:32 pm
Quote
astrobrian - 1/9/2006 10:58 AM
If I remember seeing it rught each of the SSMEs have thier own seperate hole to blow through into the trench
uh-uh. the BOOSTERS each have their own, but the SSMEs share a 31'x34' hole.
Post by: astrobrian on 09/01/2006 06:33 pm
Post by: DaveS on 09/01/2006 06:45 pm
Post by: triddirt on 09/02/2006 02:21 pm
Post by: DaveS on 09/02/2006 02:24 pm
Quote
triddirt - 2/9/2006 4:08 PMRemoved prior to launch. Prior to RSS retract for the first launch attempt of STS-114 last year, an overhead window cover fell down and damaged the left OMS pod carrier panel and a couple of tiles on it.
Shuttle Windows Question... I was suprised to find "handles" on what looks like covers for the windows.. Is this the flight configuration OR are these covers removed prior to launch?
Read Bill Harwood's story on it here: http://spaceflightnow.com/shuttle/sts114/050712cover/
Post by: Jim on 09/02/2006 02:35 pm
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triddirt - 2/9/2006 10:08 AM
Shuttle Windows Question... I was suprised to find "handles" on what looks like covers for the windows.. Is this the flight configuration OR are these covers removed prior to launch?
Those are flight configuation and require an EVA to have them removed. The covers require a periscope and TV camera for the crew to see the runways during abort landings.
;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;)
Post by: astrobrian on 09/02/2006 03:19 pm
Do the Tyvek covers have to be done the same way to prevent the engine from backfiring? ;)
His inquiry brings up a question though, at what point in the count do they take the covers off?
Post by: Jim on 09/02/2006 03:47 pm
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astrobrian - 2/9/2006 11:06 AM
lol , nice jim , real nice, lol
Do the Tyvek covers have to be done the same way to prevent the engine from backfiring? ;)
His inquiry brings up a question though, at what point in the count do they take the covers off?
No, they burn or fall off
Just before RSS rollback
Post by: astrobrian on 09/02/2006 04:24 pm
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Jim - 2/9/2006 10:34 AMQuoteNo, they burn or fall offI knew that part, just trying add another EVA joke in with yours. :o
Post by: triddirt on 09/02/2006 05:28 pm
Post by: astrobrian on 09/02/2006 05:47 pm
Post by: Avron on 09/02/2006 07:26 pm
As noted I have seen the cable connections but again dont know where they are located.. directions please..
Post by: norm103 on 09/02/2006 07:56 pm
Post by: Jim on 09/02/2006 08:56 pm
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norm103 - 2/9/2006 3:43 PM
ok i have a question about the water that is used at lift off at the pad. first how much water is used. and second is this salt water or fresh watre? thanks
Fresh. anround 100k gallons
Post by: Jim on 09/02/2006 09:00 pm
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Avron - 2/9/2006 3:13 PM
Over the last day or two a nuber of connections are made beteen the pad and the Mobile launch platform.. I have see a pic or two of the cables between the two, but have not seen the connections for fluids... Question, where are these connections located and how are they "closed off" (protected) for launch? Diagrams and pics would be most helpful..
As noted I have seen the cable connections but again dont know where they are located.. directions please..
Fluids are on the east and west sides of the MLP. The connections are what you see on the sides of MLP posts on an empty pad. They remain open/connected during launch since they are on the sides and below the deck of the MLP. The TSM's have the umbilical disconnects at launchs.
Post by: Rybanis on 09/02/2006 09:55 pm
Post by: Jim on 09/02/2006 10:02 pm
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Rybanis - 2/9/2006 5:42 PM
Question: Has there ever been a time when KSC has run low on LOX and LH? Are there plants on site?
No
LOX plant is in Mims, FL (just north of Titusville) LH2 is in Louisana.
Post by: Avron on 09/02/2006 10:55 pm
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Jim - 2/9/2006 4:47 PMQuoteAvron - 2/9/2006 3:13 PM
Over the last day or two a nuber of connections are made beteen the pad and the Mobile launch platform.. I have see a pic or two of the cables between the two, but have not seen the connections for fluids... Question, where are these connections located and how are they "closed off" (protected) for launch? Diagrams and pics would be most helpful..
As noted I have seen the cable connections but again dont know where they are located.. directions please..
Fluids are on the east and west sides of the MLP. The connections are what you see on the sides of MLP posts on an empty pad. They remain open/connected during launch since they are on the sides and below the deck of the MLP. The TSM's have the umbilical disconnects at launchs.
Thanks Jim...
Where are the Pad /MLP electrical connects located?
Post by: dutch courage on 09/03/2006 12:11 pm
Post by: Rocket Guy on 09/03/2006 03:10 pm
http://www-pao.ksc.nasa.gov/kscpao/images/medium/05pd1134-m.jpg
http://www-pao.ksc.nasa.gov/kscpao/images/medium/05pd1136-m.jpg
http://www-pao.ksc.nasa.gov/kscpao/images/medium/05pd1137-m.jpg
Post by: Avron on 09/03/2006 03:21 pm
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Ben - 3/9/2006 10:57 AM
http://www-pao.ksc.nasa.gov/kscpao/images/medium/05pd1135-m.jpg
http://www-pao.ksc.nasa.gov/kscpao/images/medium/05pd1134-m.jpg
http://www-pao.ksc.nasa.gov/kscpao/images/medium/05pd1136-m.jpg
http://www-pao.ksc.nasa.gov/kscpao/images/medium/05pd1137-m.jpg
Great pics, thanks Ben.. now where are these connections... maybe Ross has the location on one of his MLP diagrams
Post by: Svetoslav on 09/05/2006 10:58 pm
Post by: nacnud on 09/05/2006 11:29 pm
Post by: Austin on 09/05/2006 11:49 pm
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Svetoslav - 5/9/2006 3:45 PM
We know there's always a slight difference between the performance of the two SRBs. What will happen if a significant difference is noticed during launch?
If the thrust differential is minimal, it could throw off the shuttle's trajectory. If the deviation is significant and threatend populated areas as a result, RSO could be forced to make a difficult decision. Rather not go there, but I think you know what I mean.
Perhaps someone else could get into the specific structural changes/stress that a severe thrust differential would cause, but I would imagine that there would be a great deal of stress on the SRB attach points.
Post by: astrobrian on 09/06/2006 12:11 am
Post by: MKremer on 09/06/2006 12:12 am
Post by: MKremer on 09/06/2006 12:17 am
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astrobrian - 5/9/2006 6:58 PM
not to mention all the control surfaces on the Orbiter itself trying to right its course.
The orbiter aero control surfaces are locked into a pre-programmed pattern after launch (way too much stress on the orbiter structure and ET attach points to do otherwise). The SRB and SSME TVC's are what's used to control the flight path.
Post by: astrobrian on 09/06/2006 12:18 am
Post by: mkirk on 09/06/2006 12:46 am
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Svetoslav - 5/9/2006 5:45 PM
We know there's always a slight difference between the performance of the two SRBs. What will happen if a significant difference is noticed during launch?
A significant difference – and it is hard to quantify what significant would be - in SRB performance between the two SRMs would be bad!!!!
The flight control system can handle some of this, but it is the manufacturing/propellant loading process of the SRBs at the contractor plant that is designed to minimize these kinds of dispersions. Propellant in any given booster set comes from the same batch just for this reason.
Mark Kirkman
Post by: mkirk on 09/06/2006 12:59 am
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MKremer - 5/9/2006 7:04 PM
The orbiter aero control surfaces are locked into a pre-programmed pattern after launch (way too much stress on the orbiter structure and ET attach points to do otherwise).
Actually that is not a completely accurate statement.
The elevons (inboard and outboard) move to manage wing loading during load relief. Load Relief begins at about 25 seconds into the flight and works by allowing the guidance and control system to prioritize lateral accelerations over attitude control. In other words the vehicle is more responsive to errors in acceleration over errors in attitude.
While there is a preprogrammed schedule for the elevons they can & do react to sensed pressure differences at the actuators.
If you look closely at the profile shots of the launch that show a close-up view of the aft end you will see the elevons move (differentially) during ascent. Another good shot of this came from the forward SRB cameras from STS-121 – In those shots you see the elevons slowly move out of frame as first stage progresses.
Mark Kirkman
Post by: astrobrian on 09/06/2006 01:14 am
Post by: MKremer on 09/06/2006 01:32 am
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mkirk - 5/9/2006 7:46 PMQuoteMKremer - 5/9/2006 7:04 PM
The orbiter aero control surfaces are locked into a pre-programmed pattern after launch (way too much stress on the orbiter structure and ET attach points to do otherwise).
Actually that is not a completely accurate statement.
I know. ;)
I should have just said the wing surfaces only move to reduce stress on the orbiter, but aren't actually used to help control the flight of the entire stack itself.
Post by: Avron on 09/06/2006 04:18 am
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MKremer - 5/9/2006 9:19 PMQuotemkirk - 5/9/2006 7:46 PMQuoteMKremer - 5/9/2006 7:04 PM
The orbiter aero control surfaces are locked into a pre-programmed pattern after launch (way too much stress on the orbiter structure and ET attach points to do otherwise).
Actually that is not a completely accurate statement.
I know. ;)
I should have just said the wing surfaces only move to reduce stress on the orbiter, but aren't actually used to help control the flight of the entire stack itself.
Challengers wing surfaces did some moving in the last few secs..
Ref: Rogers Commission report (1986)
T+62.484
Challenger's computers order the shuttle's right-hand "elevon," or wing flap, to move suddenly.
T+63.924
A pressure change is recorded in the right-hand outboard elevon, indicating movement.
Post by: Avron on 09/06/2006 04:20 am
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nacnud - 5/9/2006 7:16 PM
In a worst case senario where the right SRB lights and the other doesn't the stack would loop up and down into the VAB! Dunno about smaller variations.
I think the stack would just tear apart.. but lets not worry about this now..
Post by: astrobrian on 09/06/2006 04:27 am
Post by: ianeck on 09/08/2006 12:09 am
I've watched the STS-114 mcc ascent team film clip several times, and there's always one portion of it which I've found curious. Shortly after SRB sep and the "103 converged" call, we hear a call which goes something like "flight...system progress two good engines..." to which LeRoy Cain simply replies "copy" as if this was an expected event. What is being referred to when (whomever it was) says "two good engines"? There wasn't an SSME lost during ascent on 114 that I can recall at any time. Is this a call which is traditionally heard during the ascent phase?
Thanks for any responses, and I apologize if this was addressed elsewhere.
-Ian.
Post by: mkirk on 09/08/2006 12:19 am
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ianeck - 7/9/2006 6:56 PM
Hi folks. This is just my second post on the forums (on any of the threads). I continue to be amazed by the complete wealth of information (both here and L2, which i just joined yesterday). As I said in my first post (on the sts-115 portion of the forums), I'm simply just a layman, average-joe fan of the shuttle program, and so I hope the question I have isn't too simplistic.
I've watched the STS-114 mcc ascent team film clip several times, and there's always one portion of it which I've found curious. Shortly after SRB sep and the "103 converged" call, we hear a call which goes something like "flight...system progress two good engines..." to which LeRoy Cain simply replies "copy" as if this was an expected event. What is being referred to when (whomever it was) says "two good engines"? There wasn't an SSME lost during ascent on 114 that I can recall at any time. Is this a call which is traditionally heard during the ascent phase?
Thanks for any responses, and I apologize if this was addressed elsewhere.
-Ian.
The call you are refering to occurs in the Mission Control Center on the Flight Director's Loop - this call is referencing the start of the OMS Assist Burn which starts 10 second after staging (defined as the software changing to major mode 103). The two good engines are the OMS engines.
I would have to listen to the tape for the actual words but the call should go like this; "Flight, Prop, OMS Assist in progress, two good engines."
Mark Kirkman
Post by: ianeck on 09/08/2006 01:58 am
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mkirk - 7/9/2006 6:06 PMQuoteianeck - 7/9/2006 6:56 PM
Hi folks. This is just my second post on the forums (on any of the threads). I continue to be amazed by the complete wealth of information (both here and L2, which i just joined yesterday). As I said in my first post (on the sts-115 portion of the forums), I'm simply just a layman, average-joe fan of the shuttle program, and so I hope the question I have isn't too simplistic.
I've watched the STS-114 mcc ascent team film clip several times, and there's always one portion of it which I've found curious. Shortly after SRB sep and the "103 converged" call, we hear a call which goes something like "flight...system progress two good engines..." to which LeRoy Cain simply replies "copy" as if this was an expected event. What is being referred to when (whomever it was) says "two good engines"? There wasn't an SSME lost during ascent on 114 that I can recall at any time. Is this a call which is traditionally heard during the ascent phase?
Thanks for any responses, and I apologize if this was addressed elsewhere.
-Ian.
The call you are refering to occurs in the Mission Control Center on the Flight Director's Loop - this call is referencing the start of the OMS Assist Burn which starts 10 second after staging (defined as the software changing to major mode 103). The two good engines are the OMS engines.
I would have to listen to the tape for the actual words but the call should go like this; "Flight, Prop, OMS Assist in progress, two good engines."
Mark Kirkman
Thanks sir :-). Just for reference I downloaded what is likely an edited version of the flight control video from spaceflightnow.com. I'm a member of the "plus" section.
Post by: oakjon on 09/09/2006 07:21 pm
I watched today's Atlantis lift-off and had a few questions. When they give the amount of thrust produced by the unit, is that measured at a standard distance throughout the industry? (rocket,jet)
Discounting torching everything, is there much difference between thrust at say, 10' from nozzle and the bottom of flame trench? Don't know if I asked this right.
After lift off, and while climbing, toward the end of the burns it looked like the trail turned from greyish to white. Why is that. Or is it just me?
In some camera views it looked like "rings" in the SSME exhaust path. How come it looks like they "pulse"?
I too am "Joe-Blow" watcher and not an engineer, so I just thought I'd ask.
Jon
Post by: MKremer on 09/09/2006 10:53 pm
- if you mean exhaust gas velocity, yes, air resistance will slow the exhaust gas velocity the farther it travels from the engine bell
- the SRB exhaust is a light greyish tan color close up, but from a distance it looks much whiter
- sounds like you're referring to mach diamonds ( http://en.wikipedia.org/wiki/Shock_diamond )
Post by: MKremer on 09/10/2006 08:38 am
(which also means if you want to monitor something as close to real-time as possible, choose the Real feed rather then the Win-Media feed)
Post by: dutch courage on 09/10/2006 09:54 am
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MKremer - 10/9/2006 10:25 AM
Really interesting that the Real (Realmedia/RealPlayer) feed from NASA-TV is about 40 seconds ahead of the Windows Media feed.
The difference between the countdown clock (shuttle page) and the Windows Media feed is even more pronounced: 45 seconds.
Post by: MKremer on 09/10/2006 11:28 am
Post by: Mark Dave on 09/10/2006 07:18 pm
Post by: Oli4 on 09/11/2006 05:48 pm
I know ISS has CO2 scrubbers. But does the Shuttle also has a system like that? And how the O2 flow is managed inside ISS and the Shuttle?
Is there a sort of airconditioning system aboard the Shuttle? I was wondering what the temperature is inside ISS and the Shuttle? And what systems aboard are used to keep the temperature constant. Or does the temp varies at night to save energy?
O and on another issue (the gap filler). Where is the port umbilical door located? And what systems are behind it?
Thanks for answering
Post by: spaceshuttle on 09/11/2006 07:37 pm
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MarkD - 10/9/2006 2:05 PM
Say what was that black line on the LO2 feed line of the STS-115 ET? I never saw that before on the two recent launches of Discovery.
probably some random markings put on there...
Post by: spaceshuttle on 09/11/2006 07:44 pm
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oakjon - 9/9/2006 2:08 PM
Questions from a simple mind.
In some camera views it looked like "rings" in the SSME exhaust path. How come it looks like they "pulse"?
Jon
yeah, as mentioned above, it's the shockwave (the definition of the shockwaves differ from launch to launch, but can't be seen on night launches because of the brightness of the flame) which is the ripple/pulsing you probably saw, and then the diamonds are a final result.
attachments: shockwave, then diamonds.
Post by: Chris Bergin on 09/13/2006 12:01 am
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Jim - 13/9/2006 12:36 AMQuoteemarkay - 12/9/2006 6:41 PM
ET re-entry:
Has anyone ever filmed it?
On early missions "Freon" was used as a blowing agent for the insulating foam. How much damage to the Ozone Layer was caused by vaporizing this chloroflourocarbon agent in the realm of the Ozone?
What is the blowing agent now, and what is it's potential hazard to the upper atmosphere?
yes
Unquanitifiable
No hazard
Post by: emarkay on 09/13/2006 01:31 am
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Chris Bergin - 12/9/2006 6:48 PMQuoteJim - 13/9/2006 12:36 AMQuoteemarkay - 12/9/2006 6:41 PM
ET re-entry:
Has anyone ever filmed it?
On early missions "Freon" was used as a blowing agent for the insulating foam. How much damage to the Ozone Layer was caused by vaporizing this chloroflourocarbon agent in the realm of the Ozone?
What is the blowing agent now, and what is it's potential hazard to the upper atmosphere?
yes
Unquanitifiable
No hazard
Thanks.
Any links to ET re-entry videos?
Found link to old and new ET foam via CAIB report page 129:
"In an effort to reduce its use of chlorofluorocarbons (CFCs), NASA had switched from a CFC-11 (chlorofluorocarbon) blowing agent to an HCFC-141b blowing agent beginning with External Tank-85, which was assigned to STS-84. (The change in blowing agent affected only mechanically applied foam. Foam that is hand sprayed, such as on the bipod ramp, is still applied using CFC-11.)"
Post by: Chris Bergin on 09/13/2006 01:47 am
The only thing that comes near is something we worked real hard to get hold of for L2 - and we got four. STS-81, 86, 78, 94 Re-entry videos plus flight deck audio, and two STA landing videos.
Those STS re-entry videos are totally stunning, not just for the view on the way in, but the chatter in the flight deck is interesting (and funny in some). The videos are from the HUDs (Heads Up Display) Flight Deck camera, from something like 100,000 ft up (could be more, the HUD doesn't come up until a few minutes later)....but what a view leaving space and the stars!
Screenshot:
Post by: shuttlefan on 09/13/2006 02:11 am
Post by: Mark Max Q on 09/13/2006 02:13 am
Post by: emarkay on 09/13/2006 02:17 am
I recall a few monochrome stills taken over India ( I think), but no motion pictures, Curious as to the color of the plasma and if there's any "exploding" water vapor as the tanks rupture.
Post by: Chris Bergin on 09/13/2006 02:20 am
There are photos from the ground, none from space. Try using the search function as that might help locate them on here...pretty sure I've seen some. Nothing all that interesting though.
Post by: astrobrian on 09/13/2006 02:53 am
Post by: astrobrian on 09/13/2006 02:59 am
Post by: Jim on 09/13/2006 11:26 am
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shuttlefan - 12/9/2006 9:58 PM
Did NASA ever give any thought to actually trying to fly any of the abort modes to prove they would work in a real emergency?
RTLS was a candidate for the first launch until they realized it was harder than an actual orbital flight
Post by: ianeck on 09/14/2006 01:23 am
Post by: astrobrian on 09/14/2006 02:07 am
Post by: DaveS on 09/14/2006 02:14 am
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astrobrian - 14/9/2006 3:54 AMSure, here if you're L2: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=4089&posts=2&start=1
If you have L2, I think there was just such a document if you were "applying" for that job. Having no luck finding the link though. Anyone else able to help out?
Post by: ianeck on 09/14/2006 03:34 am
Post by: oakjon on 09/14/2006 06:48 pm
Jon (Simple Mind)
Post by: Jim on 09/14/2006 10:04 pm
Post by: Hanny on 09/15/2006 12:20 am
In any case, I'd like to start off with a broadcasting-related question about the launches. I've become a huge fan of the PAOs like Buckingham and Diller and the like. They're kind of like that guy who does all the movie trailers. You know their voice instantly. Question is... who would be NASA Select's director/tech dir. during launch days? Seems like there's literally hundreds of different camera shots... and I was wondering if it's the PAO's themselves who change the shots, or if it's an automated switcher (something like the p.o.s. "parkervision" some stations use)... or if there's a td somewhere changing the shots.
Thanks in advance for the answer! And you can be sure I'll be bugging the experts with questions here! (I was recently given the opportunity to be brought around to some of the facilities at KSC and meet some of the people working on the shuttles. I think I pestered one poor soul in OPF 2 with a dozen questions at once. Couldn't help it. Standing under a shuttle turned me into a little wide-eyed kid!)
Thanks again all, and to the site admin, keep up the good work here!
Post by: Super George on 09/15/2006 12:27 am
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Hanny - 14/9/2006 7:07 PM
Thanks again all, and to the site admin, keep up the good work here!
Heh, welcome to the site. Me thinks, due to the site admin reference, you have only seen the forum. The place is controlled by the managing editor Chris Bergin, and this is only the forum to www.nasaspaceflight.com :)
Post by: Mark Dave on 09/17/2006 09:01 pm
Post by: Jim on 09/17/2006 09:37 pm
Post by: Mark Dave on 09/17/2006 11:18 pm
Post by: MKremer on 09/17/2006 11:38 pm
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MarkD - 17/9/2006 6:05 PM
Well what are they a rubber seal or something else?
See this section for SRB field joint details:
http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts_asm.html#srb_mods
Post by: Naraht on 09/18/2006 07:00 pm
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ianeck - 13/9/2006 9:10 PMIn the old days (into the 80s) you didn't apply to become a flight director at all. One of your managers just came to you and said "guess what, you're going to be a flight director". :)
I have a question regarding the flight control team and flight controllers. What qualifies a flight controller to be a flight director? Does he or she need to have worked X number of missions at each of the FC positions (Fido, mmacs, etc?) or is it a series of exams they go through? Is it a measure of their quality of work in their previous flight control discipline? Or a mixture of all of the above?
Post by: TitanFan on 09/19/2006 06:09 am
Post by: kraisee on 09/19/2006 06:34 am
First, some payloads going to the ISS are much heavier than others, and they just couldn't fly safely on the heaviest orbiter (Discovery) so they have to fly on the lightest of the orbiters (Endeavour and Atlantis).
Then there's maintenance issues to consider. Atlantis can only fly four more missions before it must be taken out of service. Normally it would require a major maintenance operation at that point before it could fly again. A billion dollar process called an Orbiter Maintenance Down Time (OMDT) which rebuilds an orbiter over a period of roughly two years (Endeavour is currently in her OMDT, due to return next year).
Then there's at least two months between flights for any single orbiter (assuming nothing major and unforseen needs to be done in between).
And it looks like there will need to be a rescue flight for many, if not all, of the remaining flights too, so they'll need two Orbiters to be timed 'just right' to allow for an emergency flight within 30 days of each main one.
Then there is the planning and training of the crews and the teams supporting them on the ground for each mission. This process alone takes two years or so, and has to be scheduled to fit with all the other work going on.
Assuming there's still 'wiggle room' after all those issues, they then have to work out a schedule for daylight launches, and launches which don't interfere with Progress supply ships and Soyuz crew missions, soon to be joined by ESA ATV flights and Japanese JTV flights too - although often enough the partners help fit their launches in around Shuttle flights because they know how temperamental and delicate the STS system can be regarding schedules.
With all those factors at work, if there is more than one available for a particular slot and mission, then they'll try to "balance out" the number of flights between the orbiters. They prefer to use them with fewer flights under their belts than more. The more they've flown, the more "worn" they get.
There are certainly many other factors at work too, but that's a bunch to start contemplating.
Ross.
Post by: Jim on 09/19/2006 11:50 am
Quote
TitanFan - 19/9/2006 1:56 AM
How does NASA decide which shuttle is going to fly which mission? By the time NASA schedules the mission, do they already know which shuttle is going to fly, or do they schedule mission STS-whatever years down the line and decide which shuttle is going to take it closer to launch?
Look at the shuttle manifest on L2. The seqencing of the orbiters for the fly is known. Previous years the manifest would have all the missions/payloads and which orbiters (with mod periods and payload capabilities accounted for ) they fly on defined for up to 5 years or more in the future. It would be adjusted accordingly to real life issues.
PS. Look earlier in thread about flight production
Post by: elmarko on 09/21/2006 11:05 am
How quickly does the TPS cool down after a reentry. Like, just sat there on the runway. I'm guessing the tiles are not exactly safe to touch right about now. Or does the heat dissipate quickly?
Post by: Jim on 09/21/2006 11:47 am
Post by: emarkay on 09/23/2006 04:13 pm
Post by: emarkay on 09/23/2006 04:19 pm
What information was gained from analized debris (especial larger parts) as to re-entry events that was unknown up to now (MIR and Skylab debris lost at sea, and most 'common' re-entry debris is intentionally de-orbited? For example unknown thermal, stress, chemical changes from heat/cold/pressure/comtamination from other debris, etc.) What about different materials vs. exposure to re-entry events vs. time of exposure?
Any information as to if there was any formal studies done on this?
It seems like a lot of environmental and scientific data about upper atmospheric events, as well as future designs on survivability of materials not originally intended as re-entry devices could be made.
Post by: Jorge on 09/23/2006 04:25 pm
Quote
emarkay - 23/9/2006 10:56 AM
Q I have never asked before but: Could OMS engines be used in emergency to add length to glideslope, or, from greater altutude, to enable a diversion to a different landing site (lakebed, water, flat ground, etc.) in true emergency (immediate danger at post re-entry landing site)?
No. The remaining OMS propellant is dumped after the deorbit burn, and the OMS engines themselves cannot be ignited at altitudes below 85,000 ft.
--
JRF
Post by: astrobrian on 09/23/2006 04:26 pm
Post by: Jorge on 09/23/2006 04:31 pm
Quote
emarkay - 23/9/2006 11:02 AM
Columbia disaster Q's:
What information was gained from analized debris (especial larger parts) as to re-entry events that was unknown up to now (MIR and Skylab debris lost at sea, and most 'common' re-entry debris is intentionally de-orbited? For example unknown thermal, stress, chemical changes from heat/cold/pressure/comtamination from other debris, etc.) What about different materials vs. exposure to re-entry events vs. time of exposure?
Any information as to if there was any formal studies done on this?
It seems like a lot of environmental and scientific data about upper atmospheric events, as well as future designs on survivability of materials not originally intended as re-entry devices could be made.
Quite a bit has been learned, but too much to list in a post. See the CAIB report, v.1, section 3.7 for a summary and Appendix D.11 for more detail.
--
JRF
Post by: Jorge on 09/23/2006 04:34 pm
Quote
astrobrian - 23/9/2006 11:09 AM
I am wanting to know if NASA has anyone filming reentry from somewhere in the western gulf of Mexico ?
Yes, two WB-57s and several other aircraft I can't remember offhand. They've been positioned to photograph entries starting with STS-114, but on 114 they couldn't get any footage due to Discovery being diverted to Edwards.
--
JRF
Post by: astrobrian on 09/23/2006 05:58 pm
Post by: Jorge on 09/23/2006 07:43 pm
Quote
astrobrian - 23/9/2006 12:41 PM
what about 121 and 115? and are we here on the site going to be able to see any of it? :) thanks
I've seen an IR still photo from 121, showing the fan-shaped area of increased heating behind the gap filler that NASA chose not to pull. I haven't seen any photos from 115, or video from either flight.
--
JRF
Post by: shuttlefan on 09/23/2006 09:15 pm
Quote
Jorge - 23/9/2006 2:26 PMQuoteastrobrian - 23/9/2006 12:41 PM
what about 121 and 115? and are we here on the site going to be able to see any of it? :) thanks
I've seen an IR still photo from 121, showing the fan-shaped area of increased heating behind the gap filler that NASA chose not to pull. I haven't seen any photos from 115, or video from either flight.
--
JRF
Can you tell me where on the internet that IR still photo from 121 can be viewed?
Post by: Jorge on 09/24/2006 05:41 pm
Quote
shuttlefan - 23/9/2006 3:58 PMQuoteJorge - 23/9/2006 2:26 PMQuoteastrobrian - 23/9/2006 12:41 PM
what about 121 and 115? and are we here on the site going to be able to see any of it? :) thanks
I've seen an IR still photo from 121, showing the fan-shaped area of increased heating behind the gap filler that NASA chose not to pull. I haven't seen any photos from 115, or video from either flight.
--
JRF
Can you tell me where on the internet that IR still photo from 121 can be viewed?
I don't know - I didn't see it on the internet myself. Chris may have it on L2, but not being an L2 member, I don't know either.
--
JRF
Post by: MKremer on 09/24/2006 06:06 pm
Quote
shuttlefan - 23/9/2006 3:58 PMQuoteJorge - 23/9/2006 2:26 PM
I've seen an IR still photo from 121, showing the fan-shaped area of increased heating behind the gap filler that NASA chose not to pull. I haven't seen any photos from 115, or video from either flight.
--
JRF
Can you tell me where on the internet that IR still photo from 121 can be viewed?
This is the only picture I can remember that showed it:
http://www.space.com/php/multimedia/imagegallery/igviewer.php?imgid=4127&gid=295
Post by: Jorge on 09/24/2006 09:29 pm
Quote
MKremer - 24/9/2006 12:49 PMQuoteshuttlefan - 23/9/2006 3:58 PMQuoteJorge - 23/9/2006 2:26 PM
I've seen an IR still photo from 121, showing the fan-shaped area of increased heating behind the gap filler that NASA chose not to pull. I haven't seen any photos from 115, or video from either flight.
--
JRF
Can you tell me where on the internet that IR still photo from 121 can be viewed?
This is the only picture I can remember that showed it:
http://www.space.com/php/multimedia/imagegallery/igviewer.php?imgid=4127&gid=295
Yes! That's the one.
--
JRF
Post by: dutch courage on 09/25/2006 04:23 pm
Post by: MKremer on 09/25/2006 04:42 pm
Might as well start doing it now, I guess. They aren't needed anymore and just sitting there taking up space.
Post by: Jim on 09/25/2006 04:45 pm
Post by: Jim on 09/25/2006 04:46 pm
Quote
MKremer - 25/9/2006 12:25 PM
They've been dismantling a few of the larger station module support/preparation frames lately.
Might as well start doing it now, I guess. They aren't needed anymore and just sitting there taking up space.
Not ISS but Spacelab
Post by: dutch courage on 09/25/2006 05:19 pm
Quote
Jim - 25/9/2006 6:28 PM
They are removing all the Spacelab stands since it has been shut down and the shuttle will soon. LM will assemble the CEV in there
Will we be able to see the CEV being assembled in the O&C building?
Or just the final preperations for launch?
Post by: Jim on 09/25/2006 05:28 pm
Post by: GirlygirlShuttlefan on 09/28/2006 06:48 pm
Post by: Jim on 09/28/2006 06:50 pm
Post by: GirlygirlShuttlefan on 09/28/2006 06:52 pm
Quote
Jim - 28/9/2006 1:33 PM
The control surfaces are moving to reduce the aero stress on the wings. They are only dead weight and drag on the way up
Thanks, I understand now.
Post by: Launch Fan on 09/28/2006 07:22 pm
Post by: shuttlefan on 10/02/2006 07:12 pm
Post by: Jim on 10/02/2006 07:21 pm
PS. Technicans do the work and Engineers direct the work.
Post by: norm103 on 10/03/2006 04:36 am
Post by: MKremer on 10/03/2006 09:30 am
Post by: Jim on 10/03/2006 10:52 am
Post by: shuttlefan on 10/03/2006 01:44 pm
Quote
Jim - 2/10/2006 2:04 PM
They are actually pins and once they are installed, a band, that goes around the whole SRM, restrains them. The # of pins is in the low 140's, either 142 or 144, as I recall.
PS. Technicans do the work and Engineers direct the work.
Thanks Jim!! The band is the very-noticeable black, correct?
P.S. Engineers do analysis and technicians do work, correct? :)
Post by: shuttlefan on 10/03/2006 01:49 pm
Post by: Jim on 10/03/2006 01:53 pm
Post by: norm103 on 10/03/2006 05:16 pm
Post by: Jim on 10/03/2006 05:23 pm
Post by: hyper_snyper on 10/03/2006 06:09 pm
Post by: Jim on 10/03/2006 06:20 pm
Post by: GLS on 10/03/2006 09:15 pm
BTW, and what about STS 29R, is it 29R, or just 29? In 85 it went STS 28 and then STS 30, there was no STS 29 flown, which raises my question....
Post by: astrobrian on 10/03/2006 09:22 pm
Post by: Jim on 10/03/2006 10:49 pm
Post by: Austin on 10/03/2006 11:41 pm
Quote
hyper_snyper - 3/10/2006 10:52 AM
The Virgin Galactic website claims that Shuttle launches are very environmentally unfriendly. They claim some large number like NYC's environmental impact over a week per launch, or something like that. Is this claim true and where does it come from? I would imagine from the SRBs since SSME exhaust is water vapor.
According to the following article, the effect of SRM exhaust on the ozone/environment is minimal...
http://www.aero.org/publications/crosslink/summer2000/01.html
Post by: shuttlefan on 10/04/2006 01:29 am
Quote
Jim - 3/10/2006 8:36 AMWhy don't the crews participate anymore, just to save time in getting the Shuttle out of the VAB and to the pad?
The test was the Shuttle interface Test. The crew just participated in it. The test is still run
Post by: Jim on 10/04/2006 01:54 am
Post by: Jason on 10/04/2006 03:17 pm
Post by: Jorge on 10/04/2006 04:13 pm
Quote
Jason - 4/10/2006 10:00 AM
I've noticed on pictures of Atlantis that there is what appears to be an RCC strip below and behind the nose cone just in front of the nose gear doors, that I haven't noticed on other orbiters (or at least on Discovery). Why would it exist on one and not the other? Do or did any of the others have this strip?
It is indeed an RCC strip. It's called the "chin panel". All the orbiters have it. Lighting and age will affect the appearance of RCC panels so the chin panel is more obvious on some orbiters than others.
--
JRF
Post by: GLS on 10/04/2006 09:33 pm
Quote
Jim - 3/10/2006 11:32 PM
STS 61-B. In '85, those weren't mission designations but mission sequencial numbers
Yeah... looking at the manifests it looks to me like these numbers (28, 29, 30...) are *launch slots* or something....
Anyway, they added the "R" until STS 33R, and the STS 33 was the last *slot* "to be used" (it was STS 51-L), so this tell me that they add the "R" if that number "was used" in 85-86. But STS 29 wasn't used.... (I think it was going to be 61-A, but 61-A was moved to STS 30 or something...) ...anyway it wasn't used so one wonders if in 89 it was STS 29 or if it was STS 29R and why...
Hope this is not too complicated! ;)
Post by: meiza on 10/04/2006 10:20 pm
Quote
Austin - 4/10/2006 12:24 AM
According to the following article, the effect of SRM exhaust on the ozone/environment is minimal...
http://www.aero.org/publications/crosslink/summer2000/01.html
Well, the article surely states that in the conclusions but I'm not exactly sure how they reach them. It does show that in the short term ozone is practically depleted from near the wake in a 8 kilometer wide swath (I guess the area moves downwind) 30 to 60 minutes after the launch. But not much research is done on longer term or wider area effects, what if the compounds the rockets put there are very long-lived and keep breaking up the ozone?
Post by: Austin on 10/04/2006 10:46 pm
Quote
meiza - 4/10/2006 3:03 PMQuoteAustin - 4/10/2006 12:24 AM
According to the following article, the effect of SRM exhaust on the ozone/environment is minimal...
http://www.aero.org/publications/crosslink/summer2000/01.html
But not much research is done on longer term or wider area effects, what if the compounds the rockets put there are very long-lived and keep breaking up the ozone?
Ok, but we have been launching shuttles for 25 years now. Although I am no expert on the environment, I would imagine that if the compounds did in fact have long-term effects, the results would be apparent. Granted, 25 years is not a long time, but there would be come measurable effects by now, I would think.
Post by: spaceshuttle on 10/05/2006 01:32 am
Quote
Austin - 4/10/2006 5:29 PMQuotemeiza - 4/10/2006 3:03 PMQuoteAustin - 4/10/2006 12:24 AM
According to the following article, the effect of SRM exhaust on the ozone/environment is minimal...
http://www.aero.org/publications/crosslink/summer2000/01.html
But not much research is done on longer term or wider area effects, what if the compounds the rockets put there are very long-lived and keep breaking up the ozone?
Ok, but we have been launching shuttles for 25 years now. Although I am no expert on the environment, I would imagine that if the compounds did in fact have long-term effects, the results would be apparent. Granted, 25 years is not a long time, but there would be come measurable effects by now, I would think.
i'd think that after 10 years, we would see something...
Quote
Jim - 3/10/2006 11:32 PM
Yeah... looking at the manifests it looks to me like these numbers (28, 29, 30...) are *launch slots* or something....
Anyway, they added the "R" until STS 33R, and the STS 33 was the last *slot* "to be used" (it was STS 51-L), so this tell me that they add the "R" if that number "was used" in 85-86. But STS 29 wasn't used.... (I think it was going to be 61-A, but 61-A was moved to STS 30 or something...) ...anyway it wasn't used so one wonders if in 89 it was STS 29 or if it was STS 29R and why...
Hope this is not too complicated!
funny how the military has to be so friggin' fancy with these ridiculous codenames for the missions...
Post by: Jim on 10/05/2006 01:50 am
The numbers were KSC numeric designations. When the shuttle program decided to use the sequencial number designations, KSC has to use the "R" as a decriminator to differentiate between pre and post Challenger flights
Post by: spaceshuttle on 10/05/2006 01:56 am
Quote
Jim - 4/10/2006 8:33 PM
Not the military, it was NASA. USAF had nothing to do with it.
The numbers were KSC numeric designations. When the shuttle program decided to use the sequencial number designations, KSC has to use the "R" as a decriminator to differentiate between pre and post Challenger flights
yes in deed, lol. well, at least things are MUCH easier now-a-days... :)
Post by: DaveS on 10/06/2006 07:31 pm
Post by: shuttlefan on 10/09/2006 09:53 pm
Post by: Jim on 10/09/2006 10:00 pm
Post by: psloss on 10/09/2006 10:13 pm
Post by: spaceshuttle on 10/22/2006 05:36 pm
does the magnitude of the roll (i.e. 90, 110, 135, or 157.5 degrees) depend on the altitude in which they are targeting?
Post by: psloss on 10/22/2006 05:46 pm
Quote
spaceshuttle - 22/10/2006 1:19 PMLaunch azimuth, not altitude.
ok, about the roll program
does the magnitude of the roll (i.e. 90, 110, 135, or 157.5 degrees) depend on the altitude in which they are targeting?
Post by: Jorge on 10/22/2006 05:58 pm
Quote
psloss - 22/10/2006 12:29 PMQuotespaceshuttle - 22/10/2006 1:19 PMLaunch azimuth, not altitude.
ok, about the roll program
does the magnitude of the roll (i.e. 90, 110, 135, or 157.5 degrees) depend on the altitude in which they are targeting?
And in turn, the launch azimuth depends on the orbit inclination they are targeting.
--
JRF
Post by: spaceshuttle on 10/22/2006 07:44 pm
Post by: elmarko on 10/31/2006 08:37 am
Edit: Corrected appauling spelling and grammar.
Edit 2: Did I REALLY put shoot when I meant chute? Good lord...
Post by: Jim on 10/31/2006 11:25 am
Quote
elmarko - 31/10/2006 4:20 AM
I was just wondering, if the speedbreak in the approaching and landing phase is constantly modulated to keep the shuttle to 300 knots, how can a flight be low or high on energy at this point, resulting in a late or early shoot. Surely by this stage, every approach (weight limit for touchdown speed not withstanding) should be largely the same?
You forgot about winds. Also the energy management starts much earlier
Post by: elmarko on 10/31/2006 12:17 pm
Edited my post to correct stupid spelling errors, btw.
Post by: mkirk on 10/31/2006 03:26 pm
Quote
elmarko - 31/10/2006 3:20 AM
I was just wondering, if the speedbreak in the approach and landing phase is constantly modulated to keep the shuttle to 300 knots, how can a flight be low or high on energy at this point, resulting in a late or early chute. Surely by this stage, every approach (weight limit for touchdown speed not withstanding) should be largely the same?
Edit: Corrected appauling spelling and grammar.
Edit 2: Did I REALLY put shoot when I meant chute? Good lord...
The speed brake actually has many purposes during entry. Under normal conditions the speed brake is opened at MACH 10 to 81% to act as a trim device. This keeps the elevons from reaching full deflections (i.e. becoming saturated). Beginning at around MACH 3.2 the brake starts to ramp down (i.e. close). Below .9 MACH it really acts as an energy control tool. As the orbiter rolls out on final it tranforms into an airspeed control device.
While at any time manual control by the Commander or Pilot is possible the guidance system is the best tool for modulating the correct settings assuming guidance and nav are good. At 3000 feet the brake is retracted to an angle determined by the GPCs (general purpose computers) based on wind speed, vehicle weight, velocity, density altitude, selected aim point and crew settings specified in the GPC Horizontal Situation Display. It is adjusted again at 500 feet and then goes to full open at touchdown.
For those who have seen the Entry Video on L2, you can hear Dan Burbank and Chris Ferguson making the speed brake callouts for Brent Jett.
Mark Kirkman
Post by: spaceshuttle on 11/01/2006 12:08 pm
Post by: cabbage on 11/01/2006 12:41 pm
Post by: RamjetFDO on 11/01/2006 01:51 pm
Quote
spaceshuttle - 1/11/2006 6:51 AM possibly a jessica simpson-type question...okay, when they say [39] degree inclination, do they mean that the shuttle orbits 39 degrees AGAINST the equator (like an Angle symbol from geometry class) or [39] degrees ABOVE the equator?
Inclination is the angle of the orbit plane in relation to the equator. So, in your question above, it is the "against" answer...
![]("http://liftoff.msfc.nasa.gov/academy/rocket_sci/orbmech/orbit/orb_pic/orb2.gif")
Post by: spaceshuttle on 11/01/2006 06:20 pm
i did notice a pattern:
space stations are at 51 degrees, satellites are usually at 28 degrees, and everything else is right inbetween at 39.
Post by: Jim on 11/01/2006 06:32 pm
39 degrees is not used by anything except for a few shuttle missions that had timing requirements
Post by: spaceshuttle on 11/01/2006 06:52 pm
Quote
Jim - 1/11/2006 1:15 PM
Not exactly. The ISS is at 51.6 degrees because that is the lowest the Russians can fly to. 28 is the lowest that launch vehicles can fly out of the Cape without a plane change. 0 degress is used by comsats and the launch vehicle have to provide the plane change. 90-100 degrees are flown out of VAFB and weather, recon, earth resource and mapping satellites use them
39 degrees is not used by anything except for a few shuttle missions that had timing requirements
WOW...there's copious factors for everything! lol
Post by: spaceshuttle on 11/06/2006 11:27 pm
i know why the front of the tanks USUALLY end up lighter than rest (the RSS covers that general area), but howcome some of the tanks have weird blotches, rings, and dashes on them?
Post by: Jim on 11/06/2006 11:53 pm
Wow, save the STS-106 photo for all the discussions on the sunlight darkening the foam. The RSS shadowing is very pronounced.
Post by: spaceshuttle on 11/07/2006 12:05 am
Quote
Jim - 6/11/2006 6:36 PM
repairs.
Wow, save the STS-106 photo for all the discussions on the sunlight darkening the foam. The RSS shadowing is very pronounced.
yeah, i incorporated that (the shadowing) in the models i'm working on as it is often neglected...
but what kind of repairs were going on? was it to reduce weight?
Post by: Rob in KC on 11/07/2006 12:55 am
Post by: psloss on 11/07/2006 03:58 pm
Quote
Jim - 6/11/2006 7:36 PMLooks like this one:
repairs and modifications
Wow, save the STS-106 photo for all the discussions on the sunlight darkening the foam. The RSS shadowing is very pronounced.
http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=4560
Post by: spaceshuttle on 11/07/2006 05:50 pm
Quote
psloss - 7/11/2006 10:41 AMQuoteJim - 6/11/2006 7:36 PMLooks like this one:
repairs and modifications
Wow, save the STS-106 photo for all the discussions on the sunlight darkening the foam. The RSS shadowing is very pronounced.
http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=4560
it is. i wonder why we haven't been seeing that on the last couple tanks?
Post by: Flightstar on 11/11/2006 01:16 am
Post by: riceville98 on 11/13/2006 10:47 pm
usually puts out a key personnel list for each flight but, I can't find one
for 111
Any info would be appreciated
Brian Foss
Post by: DaveS on 11/13/2006 11:00 pm
Quote
riceville98 - 14/11/2006 12:30 AMYou already asked that in this thread and got it answered: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=5292&posts=3&start=1
Does anyone remember who the CAPCOM's were for STS 111. Bill Harwood
usually puts out a key personnel list for each flight but, I can't find one
for 111
Any info would be appreciated
Brian Foss
Post by: shuttlefan on 11/14/2006 12:11 am
Post by: Jim on 11/14/2006 12:57 am
Post by: spaceshuttle on 11/14/2006 04:34 am
Post by: Jim on 11/14/2006 05:48 am
Quote
spaceshuttle - 14/11/2006 12:17 AM
i think sts-49 was the final one...why don't they do FRF anymore?
No need, there aren't any new orbiters
Post by: spaceshuttle on 11/14/2006 06:22 am
Quote
Jim - 14/11/2006 12:31 AMQuotespaceshuttle - 14/11/2006 12:17 AM
i think sts-49 was the final one...why don't they do FRF anymore?
No need, there aren't any new orbiters
that's true, huh? i never noticed that...FRFs were for the orbiters' maiden flights...pretty neat!
Post by: Jim on 11/14/2006 06:59 am
Post by: shuttlefan on 11/14/2006 12:53 pm
Quote
spaceshuttle - 13/11/2006 11:17 PM
i think sts-49 was the final one...why don't they do FRF anymore?
Hi, spaceshuttle! FRF actually was not what I was referring to. You are correct, STS-49/Endeavour was the most recent one.
The test I am referring to, called the Main Engine Flight Readiness Test , is conducted prior to every launch, as a standard test. I THINK they basically do everything with the engines, except cycle fuel through them and ignite them. All engines you see on the Space Shuttle HAVE been fired, during a previous flight, or if it is a new engine, it has been fired on the test stand at Stennis Space Center. FRFs are definitely a thing of the past as they were only a requirement prior to the maiden flights of each of the orbiters. The second one for STS-6 was to verify the hydrogen leaks and the STS-26 FRF was not actually required, but was done as part of the recertification process.
I hope this helps explain the difference between these two tests.
:) :)
Post by: riceville98 on 11/14/2006 01:05 pm
Quote
DaveS - 13/11/2006 5:43 PMQuotericeville98 - 14/11/2006 12:30 AMYou already asked that in this thread and got it answered: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=5292&posts=3&start=1
Does anyone remember who the CAPCOM's were for STS 111. Bill Harwood
usually puts out a key personnel list for each flight but, I can't find one
for 111
Any info would be appreciated
Brian Foss
That link doesn't work so just repost your answer
Thanks
Brian
Post by: psloss on 11/14/2006 03:19 pm
Quote
riceville98 - 14/11/2006 8:48 AMIt was another poster; try this link:
That link doesn't work so just repost your answer
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=5263&posts=4&mid=83959&highlight=STS%2D111&highlightmode=1&action=search#M83959
Post by: spaceshuttle on 11/14/2006 04:51 pm
Quote
shuttlefan - 14/11/2006 7:36 AMQuotespaceshuttle - 13/11/2006 11:17 PM
i think sts-49 was the final one...why don't they do FRF anymore?
Hi, spaceshuttle! FRF actually was not what I was referring to. You are correct, STS-49/Endeavour was the most recent one.
The test I am referring to, called the Main Engine Flight Readiness Test , is conducted prior to every launch, as a standard test. I THINK they basically do everything with the engines, except cycle fuel through them and ignite them. All engines you see on the Space Shuttle HAVE been fired, during a previous flight, or if it is a new engine, it has been fired on the test stand at Stennis Space Center. FRFs are definitely a thing of the past as they were only a requirement prior to the maiden flights of each of the orbiters. The second one for STS-6 was to verify the hydrogen leaks and the STS-26 FRF was not actually required, but was done as part of the recertification process.
I hope this helps explain the difference between these two tests.
:) :)
thanx much!
Post by: outward on 11/15/2006 12:41 pm
A while back someone on this forum was asking about whether the orbiter’s thermal protection system (TPS) was hot after landing. I think the answer was, no – not to the touch. But I’m curious about something…the quantity of thermal energy that becomes stored in the TPS must be substantial considering the loss of potential and kinetic energy the orbiter experiences. Now, although the outer surface of the TPS cools during the last parts of the descent, internally there must still be a considerable quantity of heat. How long does it take the internal volume of the TPS to cool to ‘room’ temperature? And is there any concern that the TPS heat will radiate inward and over- heat critical parts of the orbiter?
Thanks, (from a curious observer)
Phil
Post by: Jim on 11/15/2006 03:15 pm
Quote
outward - 15/11/2006 8:24 AM
Hi Folks,
A while back someone on this forum was asking about whether the orbiter’s thermal protection system (TPS) was hot after landing. I think the answer was, no – not to the touch. But I’m curious about something…the quantity of thermal energy that becomes stored in the TPS must be substantial considering the loss of potential and kinetic energy the orbiter experiences. Now, although the outer surface of the TPS cools during the last parts of the descent, internally there must still be a considerable quantity of heat. How long does it take the internal volume of the TPS to cool to ‘room’ temperature? And is there any concern that the TPS heat will radiate inward and over- heat critical parts of the orbiter?
Thanks, (from a curious observer)
Phil
That's why ground cooling and purge is hooked up to the orbiter at landing
Post by: dutch courage on 11/15/2006 03:52 pm
Quote
outward - 15/11/2006 2:24 PM
How long does it take the internal volume of the TPS to cool to ‘room’ temperature? And is there any concern that the TPS heat will radiate inward and over- heat critical parts of the orbiter?
I've seen a documentary about heat shields. There was a test with a piece of TPS heated orange hot with a blowtorch. The temperature on the other side of the TPS did not raise at all.
A few seconds after removing the blowtorch it could be picked up by hand.
Pretty amazing.
Post by: elmarko on 11/15/2006 04:10 pm
Quote
outward - 15/11/2006 1:24 PM
Hi Folks,
A while back someone on this forum was asking about whether the orbiter’s thermal protection system (TPS) was hot after landing. I think the answer was, no – not to the touch. But I’m curious about something…the quantity of thermal energy that becomes stored in the TPS must be substantial considering the loss of potential and kinetic energy the orbiter experiences. Now, although the outer surface of the TPS cools during the last parts of the descent, internally there must still be a considerable quantity of heat. How long does it take the internal volume of the TPS to cool to ‘room’ temperature? And is there any concern that the TPS heat will radiate inward and over- heat critical parts of the orbiter?
Thanks, (from a curious observer)
Phil
I believe it was me that asked about the TPS and that is a very good addendum to my question, so thanks (and thanks Jim!)
Post by: outward on 11/15/2006 05:10 pm
Quote
Jim - 15/11/2006 11:58 AMQuoteoutward - 15/11/2006 8:24 AM
Hi Folks,
A while back someone on this forum was asking about whether the orbiter’s thermal protection system (TPS) was hot after landing. I think the answer was, no – not to the touch. But I’m curious about something…the quantity of thermal energy that becomes stored in the TPS must be substantial considering the loss of potential and kinetic energy the orbiter experiences. Now, although the outer surface of the TPS cools during the last parts of the descent, internally there must still be a considerable quantity of heat. How long does it take the internal volume of the TPS to cool to ‘room’ temperature? And is there any concern that the TPS heat will radiate inward and over- heat critical parts of the orbiter?
Thanks, (from a curious observer)
Phil
That's why ground cooling and purge is hooked up to the orbiter at landing
Thanks for the response.....how does ground cooling work?...does it circulate cool air through various temp sensitive components?
Post by: Jim on 11/15/2006 05:21 pm
The cooling system circulates freon through a heat exchanger that interaces with the orbiter heat rejection system (the same system that use the radiators on the payload bay doors) The orbiter system has cold plates on all the avionics and also remove heat from the crew cabin.
If the cooling and purge wasn't available at landing, the crew would power the orbiter and it would be ok. The thermal soak back isn't that bad
The purge and cooling systems are the large trailers that pull up to the aft of the orbiter right after landing.
Post by: spaceshuttle on 11/16/2006 05:30 pm
i'm gonna be on a physics field trip at disney in orlando around the time of the 117 launch, and i wanted to, does anyone know of the frequencies that i should tune to on my radio to hear launch coverage?
Post by: Jim on 11/16/2006 08:00 pm
Post by: Andrewwski on 11/19/2006 10:22 pm
Post by: Rocket Nut on 11/19/2006 11:42 pm
Quote
spaceshuttle - 16/11/2006 1:13 PM
for some reason, my thread got deleted.
i'm gonna be on a physics field trip at disney in orlando around the time of the 117 launch, and i wanted to, does anyone know of the frequencies that i should tune to on my radio to hear launch coverage?
if you are looking for scanner frequencies, UHF or VHF, try this page:
http://hometown.aol.com/allanstern/myhomepage/index.html
some of these are current:
http://www.monitoringtimes.com/html/Monitoring%20NASA%20and%20Space%20Communications.pdf
Cheers,
Larry
Post by: Jim on 11/20/2006 12:43 am
Post by: Rocket Nut on 11/20/2006 09:35 am
Quote
Jim - 19/11/2006 8:26 PM
They use trunked systems now and it is hard to scan.
Or you can buy a scanner that receives trunked systems like the one I have. I got it at Radio Shack for less than $200. I received the Delta net this week without much problem. NASA PAO hijacked the frequency a few times, but most communications were direct from the control center.
The local HAM radio club also transmits a repeater in real time on VHF.
Cheers,
Larry
Post by: spaceshuttle on 11/20/2006 07:31 pm
Quote
Rocket Nut - 19/11/2006 6:25 PMQuotespaceshuttle - 16/11/2006 1:13 PM
for some reason, my thread got deleted.
i'm gonna be on a physics field trip at disney in orlando around the time of the 117 launch, and i wanted to, does anyone know of the frequencies that i should tune to on my radio to hear launch coverage?
if you are looking for scanner frequencies, UHF or VHF, try this page:
http://hometown.aol.com/allanstern/myhomepage/index.html
some of these are current:
http://www.monitoringtimes.com/html/Monitoring%20NASA%20and%20Space%20Communications.pdf
Cheers,
Larry
oh, i was talking about, perhaps, AM/FM...
Post by: shuttlefan on 11/27/2006 12:05 am
Post by: MKremer on 11/30/2006 06:01 am
Quote
shuttlefan - 26/11/2006 6:48 PM
Overall, are night shuttle launches slightly more risky? ;)
Post-Columbia and knowing the risks of ET foam loss/impacts, and knowing there's a much reduced chance of seeing any losses or 'hits' from those at night... yes, it is more "risky" in terms of real-time monitoring, but not in terms of the Mission itself.
Apart from that, a launch at night doesn't imply anymore risk than a daylight launch - any ET foam losses or potential TPS impacts are the same regardless.
The only difference is potential ground-to-orbit detection of any impacts in real time and where they might originate from the ET.
Frankly, once the SRBs ignite and the Shuttle launches there's not a whole lot anyone can do until it reaches orbit. Even then it's a matter of determining whether there's any TPS repairs that can be done or wait for a rescue Orbiter to reach the crew on the ISS.
Post by: C5C6 on 11/30/2006 11:51 am
and, where i can find a place where the "launch calls" (T-1h / T+10min) are explained???
Post by: Jim on 11/30/2006 12:13 pm
Quote
C5C6 - 30/11/2006 7:34 AM
what is the purpose of the throttle-up call if the onboard computers command the flight until ET separation?
and, where i can find a place where the "launch calls" (T-1h / T+10min) are explained???
The call is to make sure the computers are doing their jobs.
http://countdown.ksc.nasa.gov/shuttle/countdown/cdt/indexcdt.html
You will have to find the flight calls elsewhere. Most are abort boundary calls. One other is performance call
Post by: mkirk on 12/01/2006 09:13 pm
Quote
C5C6 - 30/11/2006 6:34 AM
what is the purpose of the throttle-up call if the onboard computers command the flight until ET separation?
The "Throttle Up" call really serves as a Comm Check and Status Report...the first comm check is the "roll program" call.
Think of "Throttle Up" as a point in time after liftoff rather than a command...the call tells the crew that from the perspective of the MCC (mission control center) all of the shuttle systems are performing nominally at this point in time.
Mark Kirkman
Post by: astrobrian on 12/01/2006 10:26 pm
Post by: Do Shuttles Dream on 12/02/2006 01:15 am
Post by: lsullivan411 on 12/02/2006 01:50 am
Post by: psloss on 12/02/2006 02:00 am
Quote
Do Shuttles Dream - 1/12/2006 8:58 PMYup.
So when you hear throttle up, it's already happened?
Post by: GLS on 12/02/2006 05:03 pm
Post by: Jim on 12/02/2006 07:38 pm
Quote
GLS - 2/12/2006 12:46 PMNASA was going launch the shuttles with LSOC. The USAF would have manned some positions.
Interesting question: At KSC there's the NTD (NASA Test Director). On the launches from VAFB, was it going to be a NTD or a "AFTD (Air Force Test Director)" or what???
Whether it would have been a USAF launch director or what, the mix was still in discussion.
AFTD was an east coast call sign for the USAF payload test director
Post by: kneecaps on 12/07/2006 11:59 pm
Also what is a 'tag' in the same context?
Post by: Jim on 12/08/2006 02:14 am
Post by: kneecaps on 12/08/2006 09:57 am
Quote
Jim - 8/12/2006 2:57 AM
TAG is Tested and Guaranteed.
Thanks,
So the delta display provides information that is 'Tested and Guaranteed' ...I see. Does that mean values have been tested for reasonableness and are guaranteed by way of dual sensors/redundancy?
Post by: Jim on 12/08/2006 10:53 am
Edit:
Found the book and I was correct
"At approximately L-7 days, Marshall Space Flight Center (MSFC) (code
EE21-SSME Chief Engineers Office) supplies engine specific Tag data in what is commonly
called the MSFC Tag Letter (Fig. 1.4.2-I). The Tag data are the predicted values for the
operational parameters for each SSME at a mission elapsed time of 194 seconds (engine start +
200 seconds) and at an LO2 inlet pressure of 63 psia."
look at Figure 1.4.2-I SSME Tag letter example (Ref. 1).
After reading a bit, the delta display shows the differences between the tag and actual values. From the book
The Delta display, shown in Figure 3.1.2-VIII, shows the difference between the pre-flight
predicted (or in-flight replacement) and actual values of several parameters. Only the following
parameters are shown: HPOT DP, HPFT DP, HPOT TDT, HPFT TDT, OPOV, and FPOV. This
display can be configured to show either preflight tags or inflight tags by using the BOSS Menu
as explained above. Table 3.1.2-IV gives the MSID, nomenclature, units, and source for each
parameter displayed on the Delta display. The keymap for this table is shown in Figure 3.1.2-IX.
Post by: kneecaps on 12/08/2006 02:17 pm
Heh, if I had scanned around the book some more I would have had the answers for myself.
That's the only problem I tend to have with these NASA books, some books ASSUME you know every term and concept discussed (or that you have the book to hand which explains), other books treat the reader as a novice and explain everything. Its difficult to know which kind one is currently reading.
Post by: Avron on 12/09/2006 06:44 pm
Could someone please confim, that if they do a hold a launch at T-5, drainback and APU start has not started, (Drainback start at T-4:55?) so if they do hold we are not loosing time , LOX or performance other than loss of window time?
Post by: mkirk on 12/09/2006 07:10 pm
Quote
Avron - 9/12/2006 1:27 PM
tried to ask this one on the launch thread - but its focused on press issues so here goes...
Could someone please confim, that if they do a hold a launch at T-5, drainback and APU start has not started, (Drainback start at T-4:55?) so if they do hold we are not loosing time , LOX or performance other than loss of window time?
Yes that is correct. For International Space Station missions Hold capability at T-5 minutes is limited to the duration of the launch window. After T-5 the hold time is constrained by Drainback Hold Time which is a function of either "performance loss" or "start box" limit violations. Start Box (i.e. temperature limits for main engine start) has been discussed in earlier posts on the Shuttle Q&A thread.
Mark Kirkman
Post by: Avron on 12/09/2006 07:33 pm
your earlier post was awesome, got a lot out of it... now the next question that comes to mind if say you hold at T-5... there is no impact other than loss of window time, but at the same time you are "saving" LOX and thus performance, so if you release T-5 thus 5 mins before the end of the window, launch, would you not end up with some excess performace as you have not spend more than the five mins draining back, and would thus stay within the "start box" ( assume external conditions have impact here, i.e.. a warmer day would result in the 17in feed line having warmer LOX and thus could drain for more time before the cooler LOX take you out of the "start box" ). This extra "hold" (not lost in the hold) lox would be used to give you a slightly higher delta_v thus allow for a longer window?
Post by: LSainsbury on 12/09/2006 07:46 pm
Just a very dumb question!
When a launch is scrubbed - what happens to all the fuel loaded into the ET? I assume it just gets pumped back out again?
Cheers
Lee
Post by: mkirk on 12/09/2006 07:47 pm
Quote
Avron - 9/12/2006 2:16 PM
Mark
your earlier post was awesome, got a lot out of it... now the next question that comes to mind if say you hold at T-5... there is no impact other than loss of window time, but at the same time you are "saving" LOX and thus performance, so if you release T-5 thus 5 mins before the end of the window, launch, would you not end up with some excess performace as you have not spend more than the five mins draining back, and would thus stay within the "start box" ( assume external conditions have impact here, i.e.. a warmer day would result in the 17in feed line having warmer LOX and thus could drain for more time before the cooler LOX take you out of the "start box" ). This extra "hold" (not lost in the hold) lox would be used to give you a slightly higher delta_v thus allow for a longer window?
No not exactly, it is an either or situation. You will either have enough performance in terms of LOX based on when in the window you launch or you will violate start box limits. Hold time AFTER T-5 will be based on which of the two events occurs first - you either eat up your performace margin (i.e. lox) or you will violate the start box limit at a set time after the start of drain back.
Mark Kirkman
Post by: Chris Bergin on 12/09/2006 07:53 pm
Quote
LSainsbury - 9/12/2006 8:29 PM
Hello,
Just a very dumb question!
When a launch is scrubbed - what happens to all the fuel loaded into the ET? I assume it just gets pumped back out again?
Cheers
Lee
Yep, it gets pumped back out "Detanking" ready to be used on the next attempt.
Post by: LSainsbury on 12/09/2006 07:58 pm
Quote
Chris Bergin - 8/12/2006 8:36 PMQuoteLSainsbury - 9/12/2006 8:29 PM
Hello,
Just a very dumb question!
When a launch is scrubbed - what happens to all the fuel loaded into the ET? I assume it just gets pumped back out again?
Cheers
Lee
Yep, it gets pumped back out "Detanking" ready to be used on the next attempt.
Thought so - thanks...
(Sorry for posting a new thread btw!)
Post by: psloss on 12/09/2006 07:59 pm
Quote
mkirk - 9/12/2006 3:30 PMSorry, this might essentially be the same question as Avron's, but...
No not exactly, it is an either or situation. You will either have enough performance in terms of LOX based on when in the window you launch or you will violate start box limits. Hold time AFTER T-5 will be based on which of the two events occurs first - you either eat up your performace margin (i.e. lox) or you will violate the start box limit at a set time after the start of drain back.
For the first launch attempt, the LOX drainback hold time for the preferred T-0 was exactly five minutes; since that was exactly the amount of hold time left in the window at that point, I assumed that really meant they had less launch window than performance...is that right or were the two hold times the same?
Thanks, Mark.
Post by: mkirk on 12/09/2006 08:30 pm
Quote
psloss - 9/12/2006 2:42 PM
Sorry, this might essentially be the same question as Avron's, but...
For the first launch attempt, the LOX drainback hold time for the preferred T-0 was exactly five minutes; since that was exactly the amount of hold time left in the window at that point, I assumed that really meant they had less launch window than performance...is that right or were the two hold times the same?
Thanks, Mark.
Actually by definition Drainback Hold Time is limited to a maximum of 5 minutes and is based on the time it takes for the LOX in the Downcomer (i.e. the LO2 feedline on the outside of the tank) to drain back. If start box temperature is not viloated befor that, then Performance becomes the constraint. During the T-20 minute Brief the NTD gave the hold time and the reason...performance in the case of the first attemt.
I know I am not explaining this well and in fact I am starting to trip myself up, but I will try and find the "Text Book" answer again when things calm down after launch if someone else does not come along and give a better answer.
Mark Kirkman
Mark Kirkman
Post by: psloss on 12/09/2006 08:43 pm
Quote
mkirk - 9/12/2006 4:13 PMEvery little bit helps (I think); I did hear NTD say that it was based on performance in the briefing at T-20 and I'm starting to remember you might have made this distinction between the timing of going in/out of start box and the downcomer somewhere. Need to throw some bookmarks on those...actually, "downcomer" probably makes for a distinctive search.
I know I am not explaining this well and in fact I am starting to trip myself up, but I will try and find the "Text Book" answer again when things calm down after launch if someone else does not come along and give a better answer.
Thanks again.
Edit: hope this is OK, but for anyone else who is interested, here's Mark's original post (it might be a little slow to highlight that particular post tonight):
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=625&posts=588&mid=23596&highlight=down+comer&highlightmode=2&action=search#M23596
Post by: Jim on 12/09/2006 09:02 pm
Quote
nathan.moeller - 9/12/2006 4:31 PMQuotepaulhbell07 - 9/12/2006 3:24 PM
I still admire what they do. Are they all volunteer's or are they just picked by USA.
Ice Team is volunteers. There's at least one astronaut on the close out crew so I don't know if they're paid or not. But let's keep this thread to live updates. Shuttle Q&A thread is good for this type of question.
Just their jobs, nothing special. They get paid just like everyone else. They are part of the "forward shop", which includes the SCO's, and their regular jobs deal with the forward part of the orbiter
Post by: paulhbell07 on 12/09/2006 10:21 pm
Post by: hornet on 12/09/2006 11:08 pm
Post by: Jim on 12/10/2006 11:21 am
Quote
hornet - 9/12/2006 6:51 PM
why is the shuttle commander not refered to as captian?
The shuttle is not a ship, same as previous manned spacecraft
Post by: cape51 on 12/10/2006 02:49 pm
Post by: DaveS on 12/10/2006 03:04 pm
Quote
cape51 - 10/12/2006 4:32 PMFirst of all, the call was "Single engine press to MECO, Istres 104". Istres is one of the three Transoceanic Abort Landing(TAL) sites. 104 is in reference to SSME power level. Nominal power level is 104.5% The SSMEs can be throttled all the way up to 109% of rated power level in emergencies.
when MCC stated "press to MECO, ISIS 104." what does 104 mean?
Post by: cape51 on 12/10/2006 03:05 pm
Post by: Avron on 12/10/2006 03:12 pm
Quote
psloss - 9/12/2006 4:26 PMQuotemkirk - 9/12/2006 4:13 PMEvery little bit helps (I think); I did hear NTD say that it was based on performance in the briefing at T-20 and I'm starting to remember you might have made this distinction between the timing of going in/out of start box and the downcomer somewhere. Need to throw some bookmarks on those...actually, "downcomer" probably makes for a distinctive search.
I know I am not explaining this well and in fact I am starting to trip myself up, but I will try and find the "Text Book" answer again when things calm down after launch if someone else does not come along and give a better answer.
Thanks again.
Edit: hope this is OK, but for anyone else who is interested, here's Mark's original post (it might be a little slow to highlight that particular post tonight):
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=625&posts=588&mid=23596&highlight=down+comer&highlightmode=2&action=search#M23596
On LOX Drainback... from Mark's post..''“Drain Back Hold Time” is defined as the time past the planned T - 0 that the launch sequence can be held during LO2 drain back until all the performance margin has drained away''
Note that its the time of holding past the planned T-0. (thus takes into accound the 18lbs/sec drainback that happens in a normal count from T-5 down to T-0)
So what I get is Drain Back Hold Time is the time one can sit on the pad after T-5 in a HOLD, where the performance margin is still within bonds and at the same time inlet temps "start box" is not violated.. in the past two attempts its has been the performance margin that has caused the limit of the '“Drain Back Hold Time”. I does not take into account the window from what I read.
Thus, and this is what I want to get right... if there is zero hold past T-5 and a launch happens, then the vehicle must have additional performance as none of the “Drain Back Hold Time” performace margin was consumed in a hold.
Thanks
Avron
Post by: gordo on 12/10/2006 08:07 pm
Post by: psloss on 12/10/2006 08:20 pm
Quote
Avron - 10/12/2006 10:55 AMMark will have to answer that, but thought I'd note it's probably after drainback starts, normally at T-4:55. I was recently reminded of the STS-51B count, where LOX replenish terminate/drainback start didn't occur automatically, which caused the clock to hold at the T-4 GLS milestone.
So what I get is Drain Back Hold Time is the time one can sit on the pad after T-5 in a HOLD
Whatever caused that situation may no longer be possible due to changes in process, but in that case drainback was started manually and then they waited 55 seconds before picking up the clock at T-4.
Post by: Jim on 12/10/2006 08:32 pm
Quote
gordo - 10/12/2006 3:50 PM
Why is nominal SSME power not defined as 100%, rather than the 104.5%? Seems a strange way of working.
The SSME's were rated at 375,000 lbs thrust at 100% power level. they found later that they had margins that allow 4.5% more power
Post by: kneecaps on 12/11/2006 10:57 pm
So my questions are:
What is the gas being vented from the ssme nozzles prior to launch?
Where is it coming from (nozzle drain line?)?
Which engine prestart activity is it part of (chilldown etc?)?
Does someone know of a section it a document which covers it?
Thanks!
Post by: mkirk on 12/11/2006 11:55 pm
Quote
kneecaps - 11/12/2006 5:40 PM
I've been pouring over the booster systems brief to try and work out exactly what is being vented from the SSME nozzles prior to launch. I used to think it was N2 as part of Purge Seq 3 which was replaced with Helium in Purge Seq 4...however I noticed that the 'venting' continues after the start of the Purge Seq 4 purges......
So my questions are:
What is the gas being vented from the ssme nozzles prior to launch?
Where is it coming from (nozzle drain line?)?
Which engine prestart activity is it part of (chilldown etc?)?
Does someone know of a section it a document which covers it?
Thanks!
The white gas you see venting from the SSME Nozzles is Oxygen. Oxygen which is used to chill the engine down to cryogenic temperatures, flows in from the Tail Service Mast (TSM) through the orbiter's fill/drain valves and into the oxygen manifold, in passes through the LO2 prevalves and into the low and high pressure oxidizer turbopumps. A small amount of O2 flows out of the turbopump drains and is vented through the drain line at the bottom of the nozzle bell.
Mark Kirkman
Post by: kneecaps on 12/12/2006 01:02 am
Quote
mkirk - 12/12/2006 12:38 AMQuotekneecaps - 11/12/2006 5:40 PM
I've been pouring over the booster systems brief to try and work out exactly what is being vented from the SSME nozzles prior to launch. I used to think it was N2 as part of Purge Seq 3 which was replaced with Helium in Purge Seq 4...however I noticed that the 'venting' continues after the start of the Purge Seq 4 purges......
So my questions are:
What is the gas being vented from the ssme nozzles prior to launch?
Where is it coming from (nozzle drain line?)?
Which engine prestart activity is it part of (chilldown etc?)?
Does someone know of a section it a document which covers it?
Thanks!
The white gas you see venting from the SSME Nozzles is Oxygen. Oxygen which is used to chill the engine down to cryogenic temperatures, flows in from the Tail Service Mast (TSM) through the orbiter's fill/drain valves and into the oxygen manifold, in passes through the LO2 prevalves and into the low and high pressure oxidizer turbopumps. A small amount of O2 flows out of the turbopump drains and is vented through the drain line at the bottom of the nozzle bell.
Mark Kirkman
Thanks Mark,
Now that makes sense, I think the booster systems brief has thrown me off track somewhere...it shows in purge Seq 3 GN2 purges into the turbopumps exiting via the turbopump drains....and in Seq 4 the PCA switches this to Helium.....prehaps i'm misunderstanding (plenty of pitfalls in comprehension of the SSME i've discovered).
Or could this be happening in addition to the O2 flow in through the oxygen manifold --> prevalves ---> turbopumps?
Post by: Avron on 12/12/2006 02:18 am
Avron - 11/12/2006 9:51 PM
Jim - 11/12/2006 9:48 PM
the flight plan
How long until KU, Jim?
The flight plan is on the first post and more detail on L2
-----------------------------------
Jim
how do I decode this?
Post by: Avron on 12/12/2006 02:20 am
(From live thread)
------------------
There is a listing of the KU band coverage for each orbit listed in the summary timeline of each flight day's execute package.
Look in the TDRS section near the bottom of the page of the summary timeline. There are three lines listed in the TDRS section on the lower left hand side of the timeline, TDRS West (TDRS W), TDRS EAST (TDRS E) and TDRS Z (TDRS Zone of Exclusion over the Indian Ocean). There is a black line beside each TDRS that shows when the shuttle is in communication range (voice) for that TDRS and below that line, there may be a white unshaded box or line that I think shows the video coverage that is available for that orbit with the TDRS indicated. I may have reversed these meanings of the lines shown, so someone can please correct me if I am wrong. The daily flight day execute packages are available at this location:
http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts116/ne...
They have been posted in the early afternoons (Eastern time) during this mission. Hope this helps you out.
Richard
Post by: Jim on 12/12/2006 11:26 am
TDRS band reflects the three TDRS satellites that will be used for Orbiter coverage (East,
West, and Z) and their longitudinal position. The data shown contains Ku-band coverage
(unshaded bars) and S-band coverage (solid bars).
TDRS Z currently does not have the capability for DTV, therefore can not be used for critical
damage detection. Nor is TDRS Z considered acceptable for PAO events. OCA downlink is
limited to 2 Mbps on TDRS Z.
Post by: mkirk on 12/12/2006 05:08 pm
Quote
kneecaps - 11/12/2006 7:45 PM
Thanks Mark,
Now that makes sense, I think the booster systems brief has thrown me off track somewhere...it shows in purge Seq 3 GN2 purges into the turbopumps exiting via the turbopump drains....and in Seq 4 the PCA switches this to Helium.....prehaps i'm misunderstanding (plenty of pitfalls in comprehension of the SSME i've discovered).
Or could this be happening in addition to the O2 flow in through the oxygen manifold --> prevalves ---> turbopumps?
You basically have Hydrogen, Oxygen, Nitrogen, and Helium flowing through the engine during the various purges. The purpose of all of the purges is to thermally condition the engine and components, dry the engine in the case of the GN2, and maintain a positive pressure to prevent contamination of the lines with dust and moisture. The heilum is used on the fuel side because nitrogen would freeze at the cryogenic temperatures of the LH2. After tanking starts the Bleed valves allow the flow of hydrogen and oxygen within their respective systems as well in conjunction with the the helium/nitrogen flows.
The flow rate increases for the fuel system purge (i.e. the H2 side) during Purge Sequence 4. Another difference is that helium is used in bursts during sequence 3 and 4 for the intermediate seal (IMSL) purge. The idea with the IMSL is to keep the H2 and O2 separate…this is more critical during engine operation when hot hydrogen rich gas is used to drive the High Pressure Oxidizer Turbopump which is used to flow cold liquid oxygen.
Also FYI, the copy of the Booster Systems Brief you are using only covers section 1, there are 7 other sections which discuss all of the plumbing in the MPS, ET Systems and Tanking Operations, SRB systems, and Cryo theory.
Mark Kirkman
Post by: shuttlefan on 12/12/2006 06:09 pm
Post by: DaveS on 12/12/2006 06:15 pm
Quote
shuttlefan - 12/12/2006 7:52 PMET Tanking: Yes. Mike Leinbach stated this during the post-launch press conference.
About the STS-116 countdown to the on-time launch Saturday Dec. 9th, was that the latest-ever in a countdown that they retracted the Rotating Service Structure, and also was that the latest-ever that they began fueling the ET? ;)
Post by: psloss on 12/12/2006 07:16 pm
Quote
mkirk - 12/12/2006 12:51 PMHey Mark,
The flow rate increases for the fuel system purge (i.e. the H2 side) during Purge Sequence 4. Another difference is that helium is used in bursts during sequence 3 and 4 for the intermediate seal (IMSL) purge.
What is the noise that is occasionally heard when NASA TV has the microphones up (and the commentary is quiet) at T-4 minutes? Is that the helium burst you refer to here?
Thanks.
Post by: mkirk on 12/12/2006 10:14 pm
Quote
psloss - 12/12/2006 1:59 PMQuotemkirk - 12/12/2006 12:51 PMHey Mark,
The flow rate increases for the fuel system purge (i.e. the H2 side) during Purge Sequence 4. Another difference is that helium is used in bursts during sequence 3 and 4 for the intermediate seal (IMSL) purge.
What is the noise that is occasionally heard when NASA TV has the microphones up (and the commentary is quiet) at T-4 minutes? Is that the helium burst you refer to here?
Thanks.
Bursts might have been a poor choice of words, I was just trying to convey that the flow of helium – especially during sequence 3 – is not steady.
As far as I know the noise we are hearing is from the APUs. Obviously I have never been at the Pad after T-5 minutes and I have only been around the orbiter, "post landing", after the APUs were already down…but I believe the pulsing sound is the APUs. You can also hear the same sound just after landing on the NASA audio. I realize it does not sound like the APUs on a traditional aircraft which sound like small jet engines – which is what they are on most aircraft.
Mark Kirkman
Post by: Jim on 12/12/2006 10:44 pm
Post by: psloss on 12/12/2006 10:58 pm
It doesn't sound to me like the APUs, but that's why I'm curious, because it doesn't sound to me like the APUs.
Commentary or just not having the sound at the pad mixed that high often makes it hard to hear this sound or inaudible to me.
Post by: STS-500Cmdr on 12/12/2006 11:13 pm
BTW--that sound is the APUs usually hear it a few seconds after the PLT starts them--sometimes you dont hear it for some reason. But i love that sound--it sounds like shes alive--give the shuttle that much more personality to it.
Post by: psloss on 12/12/2006 11:49 pm
Quote
psloss - 12/12/2006 6:41 PMActually not that difficult to find a few examples of what I'm hearing, but even as audio clips they're too big to attach here, so I'll see about posting the video excerpts on L2 in a little bit and seeing if you folks can identify what the sound is...
The noise I'm referring to occurs "once" more or less -- right at T-4 minutes, which is why I always associated with the GLS milestone and call from the console operator that followed it...I'll see if I can pull together a few audio clips.
It doesn't sound to me like the APUs, but that's why I'm curious, because it doesn't sound to me like the APUs.
Commentary or just not having the sound at the pad mixed that high often makes it hard to hear this sound or inaudible to me.
Post by: Austin on 12/13/2006 02:58 am
Quote
psloss - 12/12/2006 4:32 PMQuotepsloss - 12/12/2006 6:41 PMActually not that difficult to find a few examples of what I'm hearing, but even as audio clips they're too big to attach here, so I'll see about posting the video excerpts on L2 in a little bit and seeing if you folks can identify what the sound is...
The noise I'm referring to occurs "once" more or less -- right at T-4 minutes, which is why I always associated with the GLS milestone and call from the console operator that followed it...I'll see if I can pull together a few audio clips.
It doesn't sound to me like the APUs, but that's why I'm curious, because it doesn't sound to me like the APUs.
Commentary or just not having the sound at the pad mixed that high often makes it hard to hear this sound or inaudible to me.
I assume you're referring to the continous "shuck-shuck, shuck-shuck" heard around the T-4 minute mark. It is definitely the APUs. I always wondered, though, why it takes a full minute for them to be audible, when the PLT starts them at T-5. I have always assumed that it took several seconds for them to power up, hence the delay in the sound being audible.
Mr. Copella, if you're around, can you confirm, sir?
Post by: psloss on 12/13/2006 03:06 am
Quote
Austin - 12/12/2006 10:41 PMNo, the chugging of the APUs can be heard before, during, and after the noise I'm referring to...
I assume you're referring to the continous "shuck-shuck, shuck-shuck" heard around the T-4 minute mark.
Post by: Austin on 12/13/2006 03:10 am
Quote
psloss - 12/12/2006 7:49 PMQuoteAustin - 12/12/2006 10:41 PMNo, the chugging of the APUs can be heard before, during, and after the noise I'm referring to...
I assume you're referring to the continous "shuck-shuck, shuck-shuck" heard around the T-4 minute mark.
Hmm....you've got me stumped then.
If you find a launch video where the sound is particularly noticeable, post it if you would. I'm curious now.
Post by: psloss on 12/13/2006 03:14 am
Quote
Austin - 12/12/2006 10:53 PMWe're working on it...bad timing on my part, though, since the staff and some of the regulars here are busy covering STS-116.
Hmm....you've got me stumped then.
If you find a launch video where the sound is particularly noticeable, post it if you would.
Post by: Austin on 12/13/2006 03:20 am
Post by: mkirk on 12/13/2006 02:01 pm
Quote
Austin - 12/12/2006 9:41 PM
I always wondered, though, why it takes a full minute for them to be audible, when the PLT starts them at T-5. I have always assumed that it took several seconds for them to power up, hence the delay in the sound being audible.
Yes, it does take a few seconds to throw all of the switches and to get the APUs up to speed…initially for STS-1 & 2 the Pilot would start each APU 1 at a time (in serial) but that procedure was changed because it took too long. Beginning with STS-3 the APU start procedure was changed to a parallel operation where all three APUs are started together.
The APUs are started as late in the count as possible to conserve fuel but early enough to have the hydraulics up and checked before some of the other countdown events such as the aero surface and engine gimbal movement checks are performed.
The GLS (ground launch sequencer) will verify the APU Prestart is complete at T-5 minutes 25 seconds and that the actual APU start is complete at T-4 minutes 5 seconds, if they are not then a hold in the countdown will occur.
A certain PLT (pilot) found this out the hard way and in a very public manner a few years back. I don’t want to mention “ANDY ALLEN” by name or anything, but during the countdown for STS-46 he didn’t get all of the switches configured quickly enough during the APU Prestart and the countdown stopped at T-5 minutes for an unplanned hold of about 48 seconds…OOPS!!
The APU Prestart used to begin at T-6 minutes but now the procedure begins at T-6 minutes 15 seconds which provides a few extra seconds to check all of those switches.
Mark Kirkman
Post by: Austin on 12/13/2006 02:52 pm
Figured that was the case with the APUs. I just didn't know if the "delay" (in hearing them) was due to the amount of time required for them to power-up or for the PLT to complete switch configurations. Now I know its the latter.
I had never heard that about Andy Allen...but he did go on to command STS-62 so luckily for him, it wasn't a career-stopper. Also lucky for him...the PAO didn't not say something to the effect, "We will be holding the count at T-5 minutes to allow PLT ANDY ALLEN (echoing across the Cape -- allen, allen, allen) time to complete APU prestart switch configuration.
But seriously, I remember that during the ascent on STS-62, several seconds after the roll program, he radioed, "we're showing, uh, 45 percent on the left." (yes, sad that I actually remember these things). I don't remember the reason for the anomally (false SRB chamber pressure reading, perhaps?) but he seemed to handle it well. So if you happen upon this post, Andy we're just funnin' ya!
Post by: psloss on 12/13/2006 03:08 pm
Quote
Austin - 13/12/2006 10:35 AMThat was STS-75 -- he was CDR. It was a main engine Pc tape meter...
But seriously, I remember that during the ascent on STS-62, several seconds after the roll program, he radioed, "we're showing, uh, 45 percent on the left."
Post by: mkirk on 12/13/2006 03:09 pm
Quote
Austin - 13/12/2006 9:35 AM
But seriously, I remember that during the ascent on STS-62, several seconds after the roll program, he radioed, "we're showing, uh, 45 percent on the left." (yes, sad that I actually remember these things). I don't remember the reason for the anomally (false SRB chamber pressure reading, perhaps?) but he seemed to handle it well. So if you happen upon this post, Andy we're just funnin' ya!
I believe you are thinking about STS-75 with Andy as Commander and Doc Horowitz as Pilot.
The SSME PC (chamber pressure gauge) was showing around 45 percent at liftoff. Actual thrust was okay, the indicator was just scaled (calibrated) incorrectly.
I forget how it came up but Doc mentioned it at the SRB test last month and said from his persepective he was expecting a pad abort...then suddenly they were flying.
I was at that launch and when I heard the call I thought that such a low percentage shouldn't even be possible (not stable...hell idle is 67%) and then I thought I was about to see an abort until I heard MCC acknowledge the call from the crew by saying that they showed the engine running fine.
Mark Kirkman
Post by: psloss on 12/13/2006 03:17 pm
Quote
mkirk - 13/12/2006 10:52 AMI'm getting deja vu on this...if I recall correctly, they also got a temporary amber light on the engine shortly after liftoff (command path issue). There's also an old Florida Today interview floating in "webspace" with Andy Allen about this.
I believe you are thinking about STS-75 with Andy as Commander and Doc Horowitz as Pilot.
The SSME PC (chamber pressure gauge) was showing around 45 percent at liftoff. Actual thrust was okay, the indicator was just scaled (calibrated) incorrectly.
I forget how it came up but Doc mentioned it at the SRB test last month and said from his persepective he was expecting a pad abort...then suddenly they were flying.
Post by: psloss on 12/13/2006 03:29 pm
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=1655
Post by: Fred Clausen on 12/13/2006 03:41 pm
I am curious how the shuttle missions get numbered? Why is this mission currently flying STS 116 when it is the 117th shuttle mission (I think I caught that bit of trivia from NTV, I could be wrong), and why has STS 121 flown before 116? They don't seem to be going in order, and it is not based on how many shuttle missions have flown before.
Post by: Jim on 12/13/2006 03:46 pm
Post by: Austin on 12/13/2006 10:19 pm
Quote
mkirk - 13/12/2006 7:52 AM
I believe you are thinking about STS-75 with Andy as Commander and Doc Horowitz as Pilot.
The SSME PC (chamber pressure gauge) was showing around 45 percent at liftoff. Actual thrust was okay, the indicator was just scaled (calibrated) incorrectly.
I forget how it came up but Doc mentioned it at the SRB test last month and said from his persepective he was expecting a pad abort...then suddenly they were flying.
I was at that launch and when I heard the call I thought that such a low percentage shouldn't even be possible (not stable...hell idle is 67%) and then I thought I was about to see an abort until I heard MCC acknowledge the call from the crew by saying that they showed the engine running fine.
Mark Kirkman
You're right...it was STS-75 aboard Columbia.
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
Thanks much for the clarification.
Post by: spaceshuttle on 12/13/2006 10:58 pm
2. Why do the rear main engines gimbal closer together after ignition?
Post by: Jim on 12/13/2006 11:04 pm
Don't understand first question. They are just in a ground position before the gimbal test
Post by: psloss on 12/13/2006 11:23 pm
Quote
Austin - 13/12/2006 6:02 PM
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
SSME 1 = center
SSME 2 = left
SSME 3 = right
Post by: shuttlefan on 12/13/2006 11:30 pm
Quote
psloss - 13/12/2006 10:00 AMQuotemkirk - 13/12/2006 10:52 AMI'm getting deja vu on this...if I recall correctly, they also got a temporary amber light on the engine shortly after liftoff (command path issue). There's also an old Florida Today interview floating in "webspace" with Andy Allen about this.
I believe you are thinking about STS-75 with Andy as Commander and Doc Horowitz as Pilot.
The SSME PC (chamber pressure gauge) was showing around 45 percent at liftoff. Actual thrust was okay, the indicator was just scaled (calibrated) incorrectly.
I forget how it came up but Doc mentioned it at the SRB test last month and said from his persepective he was expecting a pad abort...then suddenly they were flying.
So, am I correct in assuming the engine gauge already read only 45% thrust before SRB ignition?
Post by: Austin on 12/13/2006 11:33 pm
Quote
psloss - 13/12/2006 4:06 PMQuoteAustin - 13/12/2006 6:02 PM
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
SSME 1 = center
SSME 2 = left
SSME 3 = right
Ah! That makes sense now. Thanks Philip
Post by: psloss on 12/13/2006 11:36 pm
Quote
shuttlefan - 13/12/2006 7:13 PMYes -- read Mark's earlier post in this thread:
So, am I correct in assuming the engine gauge already read only 45% thrust before SRB ignition?
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=1655
It's the second to last post.
Post by: Starks on 12/14/2006 08:28 am
Post by: Jim on 12/14/2006 11:41 am
Quote
Starks - 14/12/2006 4:11 AM
Do astronauts get Internet or email in space?
yes
Post by: elmarko on 12/14/2006 11:44 am
It'd be cool to be on a forum and just post "Oh hi I'm in space LOL"
Post by: Jim on 12/14/2006 12:15 pm
Quote
elmarko - 14/12/2006 7:27 AM
No access to public internet?
It'd be cool to be on a forum and just post "Oh hi I'm in space LOL"
System isn't set up for that
Post by: mkirk on 12/14/2006 02:56 pm
Quote
Austin - 13/12/2006 5:02 PM
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
I think everyone would have been very impressed if Andy had been referring to the SRBs since there really isn’t any onboard insight into SRB chamber pressures. ;)
There are pressure transducers in each SRB that the Booster Officer in Mission Control can see that show the chamber pressure in pounds per square inch. At the SRB test firing last month in Utah they had an advanced pressure transducer they were testing which would provide an additional redundant measurement of the chamber pressure.
On the Orbiter the only cue the crew has is a flashing yellow overbright “PC<50” on the ASCENT TRAJECTORY display just before SRB separation. This tells the crew that the chamber pressure in both boosters has fallen below 50 psi and that for all practical purposes the SRBs have burned out and are no longer producing significant forward thrust. This cue means it is safe to separate from the boosters.
Mark Kirkman
Post by: kneecaps on 12/14/2006 10:06 pm
Quote
mkirk - 12/12/2006 5:51 PMQuotekneecaps - 11/12/2006 7:45 PM
Thanks Mark,
Now that makes sense, I think the booster systems brief has thrown me off track somewhere...it shows in purge Seq 3 GN2 purges into the turbopumps exiting via the turbopump drains....and in Seq 4 the PCA switches this to Helium.....prehaps i'm misunderstanding (plenty of pitfalls in comprehension of the SSME i've discovered).
Or could this be happening in addition to the O2 flow in through the oxygen manifold --> prevalves ---> turbopumps?
You basically have Hydrogen, Oxygen, Nitrogen, and Helium flowing through the engine during the various purges. The purpose of all of the purges is to thermally condition the engine and components, dry the engine in the case of the GN2, and maintain a positive pressure to prevent contamination of the lines with dust and moisture. The heilum is used on the fuel side because nitrogen would freeze at the cryogenic temperatures of the LH2. After tanking starts the Bleed valves allow the flow of hydrogen and oxygen within their respective systems as well in conjunction with the the helium/nitrogen flows.
The flow rate increases for the fuel system purge (i.e. the H2 side) during Purge Sequence 4. Another difference is that helium is used in bursts during sequence 3 and 4 for the intermediate seal (IMSL) purge. The idea with the IMSL is to keep the H2 and O2 separate…this is more critical during engine operation when hot hydrogen rich gas is used to drive the High Pressure Oxidizer Turbopump which is used to flow cold liquid oxygen.
Also FYI, the copy of the Booster Systems Brief you are using only covers section 1, there are 7 other sections which discuss all of the plumbing in the MPS, ET Systems and Tanking Operations, SRB systems, and Cryo theory.
Mark Kirkman
Thanks again Mark! Thats cleared it up somewhat for me!! I have to get my head around the bleed valves. We only have section one of the booster systems brief? There is more? Much more! FANTASTIC, thanks for that pointer :D
Post by: psloss on 12/14/2006 10:10 pm
Quote
psloss - 12/12/2006 7:32 PMIn case anyone is interested in this besides me, I'll post these sometime after STS-116 when things are a little quieter.Quotepsloss - 12/12/2006 6:41 PMActually not that difficult to find a few examples of what I'm hearing, but even as audio clips they're too big to attach here, so I'll see about posting the video excerpts on L2 in a little bit and seeing if you folks can identify what the sound is...
The noise I'm referring to occurs "once" more or less -- right at T-4 minutes, which is why I always associated with the GLS milestone and call from the console operator that followed it...I'll see if I can pull together a few audio clips.
It doesn't sound to me like the APUs, but that's why I'm curious, because it doesn't sound to me like the APUs.
Commentary or just not having the sound at the pad mixed that high often makes it hard to hear this sound or inaudible to me.
Post by: Austin on 12/14/2006 11:20 pm
Quote
mkirk - 14/12/2006 7:39 AMQuoteAustin - 13/12/2006 5:02 PM
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
I think everyone would have been very impressed if Andy had been referring to the SRBs since there really isn’t any onboard insight into SRB chamber pressures. ;)
There are pressure transducers in each SRB that the Booster Officer in Mission Control can see that show the chamber pressure in pounds per square inch. At the SRB test firing last month in Utah they had an advanced pressure transducer they were testing which would provide an additional redundant measurement of the chamber pressure.
Mark Kirkman
...And I suppose there really would not be a reason for an onboard display to gauge SRB chamber pressure anyway (aside from the PC<50 precurser to staging) since unlike the engines, they cannot be throttled back or shut off, even if there was a sudden reduction in thrust.
As Ron McNair once (fatefully) said, if something goes wrong during the first two minutes of flight, "you either ride it out or go down with the ship."
Post by: PMN1 on 12/16/2006 07:01 pm
What was to stop it being shorter but of greater diameter or longer but of reduced diameter?
Post by: hyper_snyper on 12/16/2006 07:01 pm
Post by: GoForTLI on 12/17/2006 02:41 am
Wouldn't it make more sense for the display to indicate when vehicle sunrise or sunset occurs? I would think orbital sunrise/sunset data would be much more valuable to a flight controller than the location of the terminator.
Post by: Jim on 12/17/2006 03:40 am
Quote
GoForTLI - 16/12/2006 10:24 PM
I have a question regarding the spacecraft tracking map in the FCR. I was watching EVA3 on STS-116 during the activities to retract the 4B wing of the P6 solar array. Actions and troubleshooting depended on KU-band coverage and whether or not the vehicle was in daylight. It looks like the spacecraft experiences orbital sunrise before crossing the day/night indicator on the display, and experiences sunset after crossing back to night on the display. In other words, it looks to me like the display indicates the location of the terminator on the Earth, and not where the vehicle will be over the Earth when it experiences a sunrise or sunset (which would depend on the altitude of the vehicle).
Wouldn't it make more sense for the display to indicate when vehicle sunrise or sunset occurs? I would think orbital sunrise/sunset data would be much more valuable to a flight controller than the location of the terminator.
There are brackets " [ " and "]" on the orbital track that indicate when the vehicle enters and leaves sunlight
Post by: shuttlefan on 12/17/2006 05:20 am
Quote
Austin - 14/12/2006 6:03 PMQuotemkirk - 14/12/2006 7:39 AMQuoteAustin - 13/12/2006 5:02 PM
Can't imagine Horowitz's suprise when the solids lit following such a low engine PC reading. I was thinking in terms of SRB chamber pressure as a result of Allen's "45 percent on the left" comment (thinking left/right was a reference to left or right SRB).
I think everyone would have been very impressed if Andy had been referring to the SRBs since there really isn’t any onboard insight into SRB chamber pressures. ;)
There are pressure transducers in each SRB that the Booster Officer in Mission Control can see that show the chamber pressure in pounds per square inch. At the SRB test firing last month in Utah they had an advanced pressure transducer they were testing which would provide an additional redundant measurement of the chamber pressure.
Mark Kirkman
...And I suppose there really would not be a reason for an onboard display to gauge SRB chamber pressure anyway (aside from the PC<50 precurser to staging) since unlike the engines, they cannot be throttled back or shut off, even if there was a sudden reduction in thrust.
As Ron McNair once (fatefully) said, if something goes wrong during the first two minutes of flight, "you either ride it out or go down with the ship."
Do the astronauts spend alot of time learning about the systems on the SRBs, as they have no control over them anyway? ;)
Post by: Jim on 12/17/2006 01:22 pm
Post by: Avron on 12/17/2006 03:39 pm
Post by: Jorge on 12/18/2006 05:41 am
Quote
Avron - 17/12/2006 10:22 AM
I was wondering what the avg pay of an astronaut was?
Astronauts are paid according to the standard Civil Service scale. These scales are available on the web. Astronauts are in the GS-11 to GS-14 grades. The average annual pay is somewhere in the $80k range.
--
JRF
Post by: rfoshaug on 12/18/2006 10:19 am
Today, Curbeam will perform his 4th EVA on a single mission. What is the record of number of EVA's on a single flight by the same crewmember? I guess this goes for the entire history of manned spaceflight, too, has there ever been a mission when a crewmember has performed 4 EVA's or more on the same mission?
Post by: rfoshaug on 12/18/2006 10:20 am
Post by: Radioheaded on 12/18/2006 04:13 pm
edit: Nevermind. I see that it's the Northrop strip. Where exactly is that located? Thanks in advance guys.
Post by: psloss on 12/18/2006 04:22 pm
Quote
Radioheaded - 18/12/2006 11:56 AMNOR = NORTHRUP STRIP...WHITE SANDS SPACE HARBOR NM
Very simple question: The list of CONUS sites, does NOR= Norfolk?
Have a look at the SMG forecasts, you'll see this...
http://www.srh.noaa.gov/smg/SMG_prod.php?pil=OAV&sid=JSC&version=0
Post by: rdale on 12/18/2006 04:27 pm
Post by: Radioheaded on 12/18/2006 04:41 pm
Snow showers @ Whitesands, and 74 F and sunny today here in Richmond :o
Post by: norm103 on 12/18/2006 04:47 pm
Post by: elmarko on 12/18/2006 05:13 pm
After deorbit burn, what is the usual perigee of the orbit of the orbiter? I found the STS-1 press kit, and after deorbit burn cut off it lists the orbit as being 150nm x 2nm. Is that normal for most flights? That is to say, I know it will probably vary a bit depending on the mission, but lets go for an approximation :)
Post by: rdale on 12/18/2006 05:39 pm
Post by: norm103 on 12/18/2006 05:41 pm
Post by: psloss on 12/18/2006 06:10 pm
Quote
rdale - 18/12/2006 1:22 PMI'd be curious if any the ECAL sites might be "better" than the TAL sites in that situation, too...Mark? :)
norm: I'd bet they start with the TAL sites and work down the list from there.
Post by: shuttlepilot5 on 12/19/2006 05:12 am
I mean, im used to how a commercial airliner lands by using the ILS system. Im sure you guys are familiar with the common civil aviation ILS system.
but do the space shuttle use a similar system like the ILS? Or do they just track the runway visualy?
I think the pilot of the shuttle must have some sort of "navigation/landing system". But i dont know much about the space shuttle....so it would be great if you guys could just explain the basics of the landing(ILS)
and i guess there is no chance for a go around.....they only have 1 chance..i suppose
im sure William Oefelein will do a nice landing......lol
Post by: STS-500Cmdr on 12/19/2006 05:29 am
Post by: EW-3 on 12/19/2006 08:10 am
Have been following NASA ever since watching Alan Shepard launched. My brother worked for Bendix at the Cape and before that at White Sands, and before that on the LEM at Gruman Bethpage. Had the pleasure of witnessing the first Saturn-1B go up, and then about a week later watched a Titan-3C self destruct. So I have a strong (infantile?) connection to the space program.
OK - It's 03:48 EST and I can't sleep. The last week, I've been able to follow this mission and it seems like the dreams of a little kid who watched Alan Shepard go up have been realized at least in part. Beamer is a true spaceman! What we used to dream of. It's real!
Problem is I can't sleep. I'm just so wound up...
It occurs to me that Beamer might be just a little wound up today too, even though he seems as cool as a cucumber and they are all incredibly disciplined people. But since they have tight timelines and no time for naps (?), what happens if they can't get to sleep?
Do they have a chill pill or something to wind them down a bit?
Thanks,
Al
Post by: Jim on 12/19/2006 10:51 am
Quote
EW-3 - 19/12/2006 3:53 AM
Hi, New member, so be kind ;)
Have been following NASA ever since watching Alan Shepard launched. My brother worked for Bendix at the Cape and before that at White Sands, and before that on the LEM at Gruman Bethpage. Had the pleasure of witnessing the first Saturn-1B go up, and then about a week later watched a Titan-3C self destruct. So I have a strong (infantile?) connection to the space program.
OK - It's 03:48 EST and I can't sleep. The last week, I've been able to follow this mission and it seems like the dreams of a little kid who watched Alan Shepard go up have been realized at least in part. Beamer is a true spaceman! What we used to dream of. It's real!
Problem is I can't sleep. I'm just so wound up...
It occurs to me that Beamer might be just a little wound up today too, even though he seems as cool as a cucumber and they are all incredibly disciplined people. But since they have tight timelines and no time for naps (?), what happens if they can't get to sleep?
Do they have a chill pill or something to wind them down a bit?
Thanks,
Al
they have sleeping pills available
Post by: Jim on 12/19/2006 10:52 am
Quote
STS-500Cmdr - 19/12/2006 1:12 AM
I would ECAL and US sites would come first--theres a contingency site-in just about every state--or close to it. I live in NH--Pease ANG base is always been a ECAL site or contingency site. Would be fun if she dropped into NH--a little excitement--a Space Shuttle landing in New Hampshire--the astronauts will be greeted by cows. Bob Crippen might-i'd certainly say "what a way to come to New Hampshire"--in a $3B space shuttle. I realize thats highly unlikely. On another note--why doesnt the shuttle land on the lake bed part of Edwards anymore when it lands there?? Did getting the sand out of the thing get to be too much of a pain?
Because it doesn't need to. The concrete runway is adequate and closer to the facilities
Post by: Jim on 12/19/2006 10:52 am
Quote
shuttlepilot5 - 19/12/2006 12:55 AM
i just got 1 question about the landing. how do they do it?
I mean, im used to how a commercial airliner lands by using the ILS system. Im sure you guys are familiar with the common civil aviation ILS system.
but do the space shuttle use a similar system like the ILS? Or do they just track the runway visualy?
I think the pilot of the shuttle must have some sort of "navigation/landing system". But i dont know much about the space shuttle....so it would be great if you guys could just explain the basics of the landing(ILS)
and i guess there is no chance for a go around.....they only have 1 chance..i suppose
im sure William Oefelein will do a nice landing......lol
MLS. Microwave landing system. Plus the orbiter uses GPS and INS
Post by: EW-3 on 12/19/2006 10:56 am
I would imagine it's particularly tough on first timers...
Post by: EW-3 on 12/19/2006 11:08 am
Quote
Gary - 19/12/2006 5:44 AMQuoteEW-3 - 19/12/2006 11:39 AM
Thank you Jim.....
I would imagine it's particularly tough on first timers...
Landing?
A landing is ALWAYS the commanders responsbility and not the pilots. Mark Polansky will land Discovery. William Oefelein will probably hand fly PART of the approach.
This is standard practice for a shuttle landing.
Sorry I was referring to it being difficult to sleep in space for first timers. Night launches must make it even more difficult.
Post by: Gary on 12/19/2006 11:11 am
Post by: Joffan on 12/19/2006 12:27 pm
Quote
shuttlepilot5 - 18/12/2006 10:55 PMIn addition to the other answers given, there's a good guide to all the ins and outs of landing the shuttle here as a 461kB pdf (http://www-pao.ksc.nasa.gov/kscpao/nasafact/pdf/LandingSS-2005.pdf) (page 6 especially) or an overview of the timeline here (http://www.nasa.gov/mission_pages/shuttle/launch/landing101.html).
i just got 1 question about the landing. how do they do it?
I mean, im used to how a commercial airliner lands by using the ILS system. Im sure you guys are familiar with the common civil aviation ILS system.
but do the space shuttle use a similar system like the ILS? Or do they just track the runway visualy?
I think the pilot of the shuttle must have some sort of "navigation/landing system". But i dont know much about the space shuttle....so it would be great if you guys could just explain the basics of the landing(ILS)
and i guess there is no chance for a go around.....they only have 1 chance..i suppose
im sure William Oefelein will do a nice landing......lol
And yes, they have one chance only to land.
Post by: elmarko on 12/19/2006 04:57 pm
Quote
In Shuttle Down by Lee Corey, the space shuttle Atlantis is forced to make an emergency landing following a failed launch attempt. Since it's a polar orbit launch, they have to land on Easter Island.
What were the potential abort options for a Polar launch? RTLS and AoA would have been ok, but what options would have existed further along the launch site for any kind of intact sub-orbital abort? I'm not familiar with the geography of the area. Is Easter Island viable or was that a bit of artistic license used by the author?
Also, still looking for an answer to my deorbit burn perigee question, please? :)
Post by: Jim on 12/19/2006 05:36 pm
Post by: psloss on 12/19/2006 05:37 pm
Quote
elmarko - 19/12/2006 12:40 PMIt was viable; already been discussed in the forums at least once:
What were the potential abort options for a Polar launch? RTLS and AoA would have been ok, but what options would have existed further along the launch site for any kind of intact sub-orbital abort? I'm not familiar with the geography of the area. Is Easter Island viable or was that a bit of artistic license used by the author?
http://www.nasaspaceflight.com/forum/forums/thread-view.asp?tid=1050
Post by: Jim on 12/19/2006 05:49 pm
Post by: STS-500Cmdr on 12/19/2006 09:04 pm
Post by: psloss on 12/19/2006 09:34 pm
from "SR-93 (12/19/06): Early weather forecast 'iffy' for Friday"
http://www.cbsnews.com/network/news/space/current.html
Excerpt:
Quote
NASA wants to avoid a landing in New Mexico if at all possible because it would take an estimated 45 days to bring in cranes and other equipment needed for mounting the shuttle atop a transport jet for return to Florida.
Post by: mkirk on 12/19/2006 09:34 pm
Quote
elmarko - 19/12/2006 11:40 AM
Also, still looking for an answer to my deorbit burn perigee question, please? :)
Quote
Jim - 19/12/2006 12:32 PM
The perigee is negative after the deorbit burn
Not necessarily;
The De-orbit Burn is designed to target a resulting orbit that intersects Entry Interface at a specific flight path angle. The orbital path from apogee (where the burn starts) to perigee will pass thru Entry Interface.
Using the preliminary Burn Target Data for the first attempt to KSC this Friday, the burn ignition will occur at an altitude of 186.6 nautical miles and will last for 3 minutes 17 seconds and provide a retrograde Delta V of 326 feet per second (i.e. slow the orbiter’s velocity by 326 fps). This will result in an Entry Interface at 399,100 feet at a range to the runway of 4433 nautical miles…I don’t know what that equates to in HP (altitude for perigee) but it should be a small positive number.
My recollections from the many de-orbit burns I practiced in the SMS (shuttle mission simulator) and SSTs (single systems trainer) was that HP usually ranged from 5 to 18 nautical miles. When the burn starts you look at HP to make sure it is decreasing, but I must confess that I really don’t remember looking at that variable after a burn was completed unless I was practicing emergency procedures and then I would look at it to see how screwed I was – Bad Instrument Scanning Technique I Guess – but there were other things you are focused on such as residual velocities in all of the X, Y and Z axis that need to be nulled out and time/range to Entry Interface.
Mark Kirkman
Post by: elmarko on 12/19/2006 10:19 pm
I have no idea WHY they do it this way. Before that, the generally accepted method was to burn to 0km altitude for perigee. Which was technically more correct than people seem to do now :)
I'll go play some more. Thanks.
Post by: mkirk on 12/19/2006 10:22 pm
Quote
shuttlepilot5 - 18/12/2006 11:55 PM
i just got 1 question about the landing. how do they do it?
I mean, im used to how a commercial airliner lands by using the ILS system. Im sure you guys are familiar with the common civil aviation ILS system.
but do the space shuttle use a similar system like the ILS? Or do they just track the runway visualy?
I think the pilot of the shuttle must have some sort of "navigation/landing system". But i dont know much about the space shuttle....so it would be great if you guys could just explain the basics of the landing(ILS)
The shuttle uses several different sources of data for Navigation Processing by the General Purpose Computers, normally referred to as NAV.
NAV generates 3 separate state vectors. A state vector is the calculation of the orbiter’s position and velocity at a specific time. NAV continuously propagates the state vector using the equations of motion (thank you Mr. Newton). A KALMAN filter is used to blend all of the various sensors into those calculations. The sensors I am referring to are DRAG H (or drag altitude, which in simple terms is an aerodynamic model of the atmosphere's effect on the orbiter), TACAN (same as a VORTAC), Air Data Probes (similar to the PITOT STATIC system on conventional airplanes), MLS (which is the shuttle’s version of the ILS – it is a very precise system), GPS, and Radar Altimeters.
I have attached a pdf chart of how when the various sensors are used at the very bottom of this post. For instance the MLS is not really affective until around 18,000-15,000 feet which is when the orbiter is rolling out on final.
The Radar Altimeters are not processed by NAV, they are only used for crew displays and become effective as the orbiter descends thru 5000 feet.
So far GPS is not fully processed by the shuttle computers either. Currently the shuttle program is flying a “ramp up” test of the system. On the last mission, STS-115, the GPS was used for the first time in the primary (PASS) general purpose computers. The plan was to let the PASS GPCs use the GPS in the processing scheme for a little while and then inhibit them from the NAV scheme and land using the standard navigation scheme (i.e. air data probe derived data). However, GPS worked so well and accurately that Mission Control told the crew to keep it instead of the “Air Data”. In other word the GPS prediction of the orbiter’s Stated Vector was more accurate than the standard Air Data prediction.
If you saw the post landing press conference then you heard a 10 minute dissertation on how this worked from an obviously pleased Leroy Cain. Cain used to be a GNC (guidance, navigation, and control) Flight Controller in Mission Control…so he is very familiar with the system.
Anyway the plan is to use the GPS again on this flight (116) as part of the ramp up program before flying a full GPS flight on STS-117.
Mark Kirkman
P.S.
I wrote a little blurb on how the very last part of the final approach is flown in the shuttle on the first Shuttle Q&A thread here:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=625&start=271
Post by: EW-3 on 12/20/2006 12:13 am
When Beamer was performing his magic, to get around he had to feed instructions constantly to the arm drivers..
Is there a capability to go to fixed points without all the dialog?
For example in yesterdays excercise, he frequently had to go back to the same safe position. It would seem handy to
designate the safe position as a set of coordinates and then just to recall them.
Make sense?
Post by: dbhyslop on 12/20/2006 12:55 am
Quote
mkirk - 19/12/2006 6:05 PM
So far GPS is not fully processed by the shuttle computers either. Currently the shuttle program is flying a “ramp up” test of the system. On the last mission, STS-115, the GPS was used for the first time in the primary (PASS) general purpose computers. The plan was to let the PASS GPCs use the GPS in the processing scheme for a little while and then inhibit them from the NAV scheme and land using the standard navigation scheme (i.e. air data probe derived data). However, GPS worked so well and accurately that Mission Control told the crew to keep it instead of the “Air Data”. In other word the GPS prediction of the orbiter’s Stated Vector was more accurate than the standard Air Data prediction.
This is fascinating.
My father is a soon-to-be-retired airline pilot. He has a story about flying with a guy who brought a GPS along, back when they were the new thing and only, well, airline captains could afford them. The idea was they would see how accurate it was based against the airplane's inertial navigation system.
Now, of course, they know that they were actually seeing how accurate the INS was against the GPS!
Dan
Post by: Jim on 12/20/2006 01:11 am
Quote
EW-3 - 19/12/2006 7:56 PM
was wondering about EVAs....
When Beamer was performing his magic, to get around he had to feed instructions constantly to the arm drivers..
Is there a capability to go to fixed points without all the dialog?
For example in yesterdays excercise, he frequently had to go back to the same safe position. It would seem handy to
designate the safe position as a set of coordinates and then just to recall them.
Make sense?
safe position is relative to where the arm is mounted and/or if it is on the MT. Also what would the EV astronaut use for reference. He has no display or measurement system. A jumble of numbered coordinates would have little meaning to him
Post by: Jim on 12/20/2006 01:11 am
Quote
mkirk - 19/12/2006 6:05 PMQuoteshuttlepilot5 - 18/12/2006 11:55 PM
i just got 1 question about the landing. how do they do it?
I mean, im used to how a commercial airliner lands by using the ILS system. Im sure you guys are familiar with the common civil aviation ILS system.
but do the space shuttle use a similar system like the ILS? Or do they just track the runway visualy?
I think the pilot of the shuttle must have some sort of "navigation/landing system". But i dont know much about the space shuttle....so it would be great if you guys could just explain the basics of the landing(ILS)
The shuttle uses several different sources of data for Navigation Processing by the General Purpose Computers, normally referred to as NAV.
NAV generates 3 separate state vectors. A state vector is the calculation of the orbiter’s position and velocity at a specific time. NAV continuously propagates the state vector using the equations of motion (thank you Mr. Newton). A KALMAN filter is used to blend all of the various sensors into those calculations. The sensors I am referring to are DRAG H (or drag altitude, which in simple terms is an aerodynamic model of the atmosphere's effect on the orbiter), TACAN (same as a VORTAC), Air Data Probes (similar to the PITOT STATIC system on conventional airplanes), MLS (which is the shuttle’s version of the ILS – it is a very precise system), GPS, and Radar Altimeters.
I have attached a pdf chart of how when the various sensors are used at the very bottom of this post. For instance the MLS is not really affective until around 18,000-15,000 feet which is when the orbiter is rolling out on final.
The Radar Altimeters are not processed by NAV, they are only used for crew displays and become effective as the orbiter descends thru 5000 feet.
So far GPS is not fully processed by the shuttle computers either. Currently the shuttle program is flying a “ramp up” test of the system. On the last mission, STS-115, the GPS was used for the first time in the primary (PASS) general purpose computers. The plan was to let the PASS GPCs use the GPS in the processing scheme for a little while and then inhibit them from the NAV scheme and land using the standard navigation scheme (i.e. air data probe derived data). However, GPS worked so well and accurately that Mission Control told the crew to keep it instead of the “Air Data”. In other word the GPS prediction of the orbiter’s Stated Vector was more accurate than the standard Air Data prediction.
If you saw the post landing press conference then you heard a 10 minute dissertation on how this worked from an obviously pleased Leroy Cain. Cain used to be a GNC (guidance, navigation, and control) Flight Controller in Mission Control…so he is very familiar with the system.
Anyway the plan is to use the GPS again on this flight (116) as part of the ramp up program before flying a full GPS flight on STS-117.
Mark Kirkman
P.S.
I wrote a little blurb on how the very last part of the final approach is flown in the shuttle on the first Shuttle Q&A thread here:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=625&start=271
You the man, Mark
Post by: rosbif73 on 12/20/2006 01:28 pm
Quote
psloss - 19/12/2006 11:17 PM
Based on what Bill Harwood wrote today, White Sands would be programmatic problem:
from "SR-93 (12/19/06): Early weather forecast 'iffy' for Friday"
http://www.cbsnews.com/network/news/space/current.html
Excerpt:QuoteNASA wants to avoid a landing in New Mexico if at all possible because it would take an estimated 45 days to bring in cranes and other equipment needed for mounting the shuttle atop a transport jet for return to Florida.
Wasn't there also a problem with sand from the landing strip resulting in major TPS work being required after STS-3 (the only White Sands landing)?
Given that there is apparently little equipment stationed at WSSH, what real advantage does it offer over other CONUS emergency landing sites?
Post by: DaveS on 12/20/2006 01:41 pm
Quote
rosbif73 - 20/12/2006 3:11 PMThat was from a dust storm, not during touchdown and rollout.
Wasn't there also a problem with sand from the landing strip resulting in major TPS work being required after STS-3 (the only White Sands landing)?
Post by: psloss on 12/20/2006 01:49 pm
Quote
rosbif73 - 20/12/2006 9:11 AMGenerally favorable weather and long runways. (Perhaps vice versa.)
Given that there is apparently little equipment stationed at WSSH, what real advantage does it offer over other CONUS emergency landing sites?
Post by: joebacsi on 12/20/2006 09:04 pm
Post by: DaveS on 12/20/2006 09:31 pm
Quote
joebacsi - 20/12/2006 10:47 PMColumbia had been modified to accept an so called Extended Duration Orbiter(EDO) cryogenic kit.
I'd really like to ask that on exactly what supplies does the number of days that a shuttle can spend in space depends? Because I remember like Columbia having a mission when it was up there for like more then 17 days... So what would it take to prepare ISS missions for a possibility of longer trips so they wouldn't face the concerns they have now, and like they could extend missions easier? I remember reading that the shuttle has the nominal capability of a 28 day mission... Sorry if this had already been asked...
The EDO cryo kit had additional LH2 and LOX tanks for the Power Reactant Storage and Distribution(PRSD) system.
This enabled Columbia to have longer duration missions than the other orbiters as the EDO cryo kit provided alot more cryogenic reactants for the three Fuel Cells.
Endeavour was delivered with a capability to accept TWO EDO cryo kits enabling her to go on 28-day missions.
But this capability was removed to save weight when ISS moved to it's current high inclination orbit-
Post by: Jim on 12/20/2006 11:42 pm
Quote
joebacsi - 20/12/2006 4:47 PM
I'd really like to ask that on exactly what supplies does the number of days that a shuttle can spend in space depends? Because I remember like Columbia having a mission when it was up there for like more then 17 days... So what would it take to prepare ISS missions for a possibility of longer trips so they wouldn't face the concerns they have now, and like they could extend missions easier? I remember reading that the shuttle has the nominal capability of a 28 day mission... Sorry if this had already been asked...
This was covered in the Shuttle Q&A thread in more detail. Nominal capability is 11. Extended is 17 and 28 was a dream. The SSPT(sp) mods will make it longer. This is all in the other thread
Post by: hutchel on 12/20/2006 11:45 pm
I've noticed that all of the landing tracks come in from the west - this seems to limit the landing opportunities. Does the shuttle not have sufficient energy from the 2 orbits prior to the ones use to make it safely to the runway?
I know in the early stages of the entry, the shuttle is not powered (all the way to the ground) and is basically flying a "ballastic" trajectory, but at some point the control surfaces become effective and the shuttle starts to behave more and more like an airplane, at which point a turn more to the north and eventually west would be conceivable - this would seem to give them a couple of more landing opportunities.
Post by: Jim on 12/21/2006 12:05 am
Not even a regular aircraft dead sticking would have that capability. glideslope would need to be almost flat.
Post by: TJL on 12/21/2006 01:59 am
Post by: DaveS on 12/21/2006 02:10 am
Quote
TJL - 21/12/2006 3:42 AMAll three.
Is the Friday forecast calling for clouds, wind or rain?
Post by: psloss on 12/21/2006 02:12 am
Quote
TJL - 20/12/2006 9:42 PMOff the top of my head, the weather for STS-108 was probably generally better, but ended up with low clouds over the end of the runway. A couple of screen shots are attached from that; these probably make it seem more dramatic than it was, but...
If I remember correctly, the weather at KSC for thr "121" landing wasn't the greatest. I don't believe there was a previous shuttle landing with that much cloud cover. Is the Friday forecast calling for clouds, wind or rain?
Post by: hutchel on 12/21/2006 10:17 am
Post by: psloss on 12/21/2006 11:48 am
Post by: shuttlefan on 12/21/2006 12:54 pm
Quote
psloss - 21/12/2006 6:31 AM
STS-121 did have a pretty late runway "redes"; the other late one I remember was for STS-30 (that was at Edwards) and it was for winds as opposed to rain showers. (There have probably been others, though, post-deorbit burn.)
During the STS-107 re-entry, they were seriously considering changing KSC runways. Someone correct me if I'm wrong, but I think it was because they were fearing the sun would be in the CDR's eyes. :(
Post by: Joffan on 12/21/2006 02:44 pm
Quote
hutchel - 20/12/2006 5:28 PMThe big-scale approach to landing come from the west because the orbiter is ...ah... orbiting, and that means huge ground-speed. The return to Earth needs to lose that orbital speed and that is done mostly through aerobraking, so that can't happen until the craft is in the atmosphere, so previous orbits are irrelevant. You'll recall that Columbia broke up over Texas, which was quite early in the aerobraking process approaching Florida. That's the sort of scale to bear in mind for the re-entry.
OK Landing track question -
I've noticed that all of the landing tracks come in from the west - this seems to limit the landing opportunities. Does the shuttle not have sufficient energy from the 2 orbits prior to the ones use to make it safely to the runway?
I know in the early stages of the entry, the shuttle is not powered (all the way to the ground) and is basically flying a "ballastic" trajectory, but at some point the control surfaces become effective and the shuttle starts to behave more and more like an airplane, at which point a turn more to the north and eventually west would be conceivable - this would seem to give them a couple of more landing opportunities.
At high speeds the shuttle can curve her track a little by attitude control. Once her speed is low enough, the orbiter can start manouevering more impressively and the approach to the KSC runway at least requires a 270degree turn. So the heading of the runway is not a problem for landing.
Post by: mark147 on 12/21/2006 05:45 pm
Mark
Post by: Joffan on 12/21/2006 06:10 pm
Post by: DaveS on 12/21/2006 06:11 pm
Quote
mark147 - 21/12/2006 7:28 PMNot an option! DN approaches would overfly CONUS and present an unacceptable risk situation if something were to go wrong during entry and lead to break-up of the orbiter.
A related question then -- why not consider landing from the opposite side of the orbit? The planned approaches for STS-116 all come from an ascending orbit (approach from South West). Surely there's also a landing opportunity from a descending orbit (approach from North West), about 12 hours later?
Mark
Post by: Jim on 12/21/2006 06:36 pm
Post by: elmarko on 12/21/2006 08:12 pm
Let's talk about OMS assists. Rather than burn the OMS engines for however long is needed, why not just fuel the OMS engine pods with enough OMS fuel for a mission MINUS what would be burned for the OMS assist if it was carried out.
I mean, if it's a question of weight, then surely not carrying that fuel would increase performance?
Post by: Joffan on 12/21/2006 08:12 pm
Quote
DaveS - 21/12/2006 11:54 AM"Unacceptable risk"... sounds like a gut reaction rather than one with any real numbers behind it. I couldn't see the additional risk amounting to more than 10e-5 ground fatalities per flight, which is effectively zero for most purposes and especially for the Shuttle given limited life. Even in "bad publicity" terms, the tragedy of shuttle breakup will not be noticeably more if a handful of people are killed on the ground (eg. Lockerbie). It must be something else - hopefully, as Jim says, mkirk will have more information.Quotemark147 - 21/12/2006 7:28 PMNot an option! DN approaches would overfly CONUS and present an unacceptable risk situation if something were to go wrong during entry and lead to break-up of the orbiter.
A related question then -- why not consider landing from the opposite side of the orbit? The planned approaches for STS-116 all come from an ascending orbit (approach from South West). Surely there's also a landing opportunity from a descending orbit (approach from North West), about 12 hours later?
Mark
Post by: Joffan on 12/21/2006 08:18 pm
Quote
elmarko - 21/12/2006 1:55 PM
I have a question that is probably very, VERY stupid, and I apologise for it in advance. The excuse I'm giving is that I just got back from my work Christmas party, so I'm a bit tipsy.
Let's talk about OMS assists. Rather than burn the OMS engines for however long is needed, why not just fuel the OMS engine pods with enough OMS fuel for a mission MINUS what would be burned for the OMS assist if it was carried out.
I mean, if it's a question of weight, then surely not carrying that fuel would increase performance?
What a great idea! In fact maybe we should remove ALL the fuel from the whole shuttle! Think how much lighter it would be then, and performance would be... would be...
OK, enough sarcasm, sorry. The weight of the fuel is an issue but overall they wouldn't carry it if it wasn't contributing more than it was expending.
Post by: elmarko on 12/21/2006 08:39 pm
That was my question, really. If the thrust to weight ratio was less than 1, then there would be no point carrying it?
Post by: mkirk on 12/21/2006 09:31 pm
Quote
psloss - 20/12/2006 8:55 PMQuoteTJL - 20/12/2006 9:42 PMOff the top of my head, the weather for STS-108 was probably generally better, but ended up with low clouds over the end of the runway. A couple of screen shots are attached from that; these probably make it seem more dramatic than it was, but...
If I remember correctly, the weather at KSC for thr "121" landing wasn't the greatest. I don't believe there was a previous shuttle landing with that much cloud cover. Is the Friday forecast calling for clouds, wind or rain?
The weather rules are pretty clearly defined, the hard part is predicting what will happen during the usually dynamic weather scenarios encountered in Florida from the time of the De-Orbit Burn (when weather has been evaluated by the Flight Control Team) and the time the shuttle arrives on final approach for the runway.
So when the go for De-Orbit is (was) given the expectation is (was) that the approach path would be clear from at least 8,000 feet down to the runway…I really don’t recall how many times (if ever) that the ceiling rule was violated when the orbiter actually arrived at the landing site.
The ceiling limits for EOM (end of mission) are 8,000 feet. This is of course more constraining than the RTLS rule of 5,000 feet. The difference is based on the freshness of the crew. On launch day they had just finished several days of simulator and STA (shuttle training aircraft) runs which gave them plenty of landing practice. Now that they have been in Zero G for several days it is assumed they are not quite as fresh and the weather rules are packed with additional safety margin.
Flight Rules define a ceiling as more than 50% coverage. You can have lower clouds but generally they have to be 2/8th coverage or less and they can not obstruct the visibility of the runway on final approach.
The ceiling rule ensures the Crew can visually acquire the runway after breaking out of the cloud deck and make any corrections to the flight path needed in cases where the Guidance and Navigation System were not as accurate as they should be. From 5,000 the Commander would only have about 18 seconds to make those corrections before beginning the Pre-Flare. So the EOM rule of 8,000 feet provides a little cushion in the amount of time available.
Mark Kirkman
Post by: mkirk on 12/21/2006 09:43 pm
Quote
Jim - 20/12/2006 6:48 PM
Cross range is the distance on either side of orbit track the orbiter can reach. The Shuttles cross range was to be 1000nmi and is 800nmi (mkirk can correct this). The distance between orbit tracks is much greater than this. The orbiter doesn't become an "real" actual aircraft until less than 100,000 feet (mkirk, help). the shutttle is still using the RCS sometimes in view of the landing sites.
I don’t recall the exact numbers for cross range and there really are too many variables to give an exact number. Jim’s answer is a good ball park explanation. The cross range limits are also a little more constrained for TAL (Transoceanic Abort Landing) than for EOM (end of mission) and are based on orbital inclination and the particular landing site.
As for RCS (reaction control system) jet usage; the various jets are phased out over the course of Entry. The Roll Jets are deactivated at about 5 minutes after Entry Interface (at a dynamic pressure of 10 pounds per square foot). The Pitch jets are deactivated about 3 or 4 minutes later when dynamic pressure is up to 40 psf and finally the yaw jets are deactivated last at Mach 1 (which is generally at an altitude of 50,000 – 55,000 feet).
Mark Kirkman
Post by: STS-500Cmdr on 12/21/2006 10:03 pm
Quote
elmarko - 21/12/2006 2:55 PM
I have a question that is probably very, VERY stupid, and I apologise for it in advance. The excuse I'm giving is that I just got back from my work Christmas party, so I'm a bit tipsy.
Let's talk about OMS assists. Rather than burn the OMS engines for however long is needed, why not just fuel the OMS engine pods with enough OMS fuel for a mission MINUS what would be burned for the OMS assist if it was carried out.
I mean, if it's a question of weight, then surely not carrying that fuel would increase performance?
To take a bit of a crack at elmarko's question. I kinda learned a little bit about OMS assist watching-and taping for later watching-a briefing with John Shannon during STS-105-he was answering a Q from Harwood.
I understand what your saying--we used to load up the OMS for what we needed for the mission. OMS assist was put on as a performance-enhancement where they loaded up the OMS tanks for MORE than was needed for the mission. You burn that just after SRB sep-that gives you about 250 lbs so you can keep that 250 lbs in the External Tank. You have that 250 lbs in th ET for contingencies, maybe if you had an engine problem-not necessarily and engine out but an engine problem like we saw on STS-93 where we had the small hole in the nozzle leaking LH2 into the plume-starved the engine a bit-the engine throttled up used more LO2 to compensate--left Columbia short by about 15 fps. This is me tryin to remember John Shannon's explanation one time. Does this help at all? Im not a NASA or USA person--i kinda wish i was--i might sound a bit like one here :)
Post by: elmarko on 12/21/2006 10:45 pm
Or am I approaching this completely wrongly.
PS: I'm sobering up, so hit me with your best answers ;)
Post by: Radioheaded on 12/21/2006 11:16 pm
Post by: ichilton on 12/21/2006 11:32 pm
Does anyone know if the landing will be covered live by any TV channels available in the UK?
Thanks
Ian
Post by: Chris Bergin on 12/21/2006 11:36 pm
Quote
ichilton - 22/12/2006 12:15 AM
Hi,
Does anyone know if the landing will be covered live by any TV channels available in the UK?
Thanks
Ian
BBC News 24 and Sky News.
Post by: ichilton on 12/21/2006 11:37 pm
Post by: Chris Bergin on 12/21/2006 11:40 pm
Quote
ichilton - 22/12/2006 12:20 AM
Thanks Chris
It's what we're here for ;)
It'd of been on ITV News Channel, but that's no longer around, I was shocked to hear the other day. Sky's usually best.
Post by: Chris Bergin on 12/22/2006 01:24 pm
Post by: Jorge on 12/22/2006 04:40 pm
Quote
Jim - 21/12/2006 1:19 PM
There are other issues with DN also. mkirk can enlighten us. Way back there use to be a density shear in the upper atmosphere
Noctilucent clouds also. There is a flight rule on this, will look it up if I get a chance.
--
JRF
Post by: Jorge on 12/22/2006 05:27 pm
Quote
Jorge - 22/12/2006 11:23 AMQuoteJim - 21/12/2006 1:19 PM
There are other issues with DN also. mkirk can enlighten us. Way back there use to be a density shear in the upper atmosphere
Noctilucent clouds also. There is a flight rule on this, will look it up if I get a chance.
--
JRF
Flight Rule A2-207. Noctilucent clouds are only an issue in the summer. Another issue is sleep-shifting; the descending opportunities are several hours after the ascending ones so crew fatigue becomes an issue. So descending opportunities are not considered for nominal EOM, but could be considered for emergencies.
Since descending opportunities won't be considered in the nominal case, public risk is not a factor unless the orbiter is "compromised" (TPS, loss of fault-tolerance in entry-critical systems).
--
JRF
Post by: hmh33 on 12/22/2006 06:16 pm
Post by: C5C6 on 12/25/2006 07:31 pm
by the way, watching sts-121 launch i heard some calls i dont understand
- "Press to ATO, select Istres" : i know what ATO and istres are, but what is 'Press to ATO, select Istres'?
- "Single Engine OPS-3" : no idea :-P ...
- "Single engine istres, 104" : whats that '104'?
- "Press to MECO" : again, i know what MECO is but what is 'press to MECO'?
- "Go for plus-x" : no idea again :-P :-P ...
thank you!!
Post by: elmarko on 12/25/2006 08:06 pm
Quote
C5C6 - 25/12/2006 8:14 PM
I just wondered, do astronauts use some kind of a drug to sleep? i find it hard to believe that with so much adrenaline flowing they are able to sleep as if everything was normal....is there any training for this issue?
by the way, watching sts-121 launch i heard some calls i dont understand
- "Press to ATO, select Istres" : i know what ATO and istres are, but what is 'Press to ATO, select Istres'?
- "Single Engine OPS-3" : no idea :-P ...
- "Single engine istres, 104" : whats that '104'?
- "Press to MECO" : again, i know what MECO is but what is 'press to MECO'?
- "Go for plus-x" : no idea again :-P :-P ...
thank you!!
Istres is one of the TAL sites for the mission, and the commander was told to "select" it, ie, in the case of a TAL, fly to that site.
Press to MECO means the shuttle is carrying enough velocity to be able to make MECO under 2 engine power if one fails
Single engine istres 104 means that if 2 engines failed, the last one could carry on at 104% of it's performance, which is the nominal power level.
Single Engine OPS 3 means that the shuttle could reach a TAL site with 2 engines out and the remaining engine at 109% power and use OPS 3 software on the shuttle computers to do it. (I think. Can someone confirm this one for me please? I remember there's something about Droop guidance but I didn't want to explode his C5C6's head ;) )
Post by: elmarko on 12/25/2006 08:12 pm
Post by: Jim on 12/25/2006 09:47 pm
Quote
elmarko - 25/12/2006 3:55 PM
And also, can someone tell me the plus x stuff in more detail please, because I can never remember which direction X actually is :)
http://spaceflight.nasa.gov/shuttle/reference/index.html
Plus X is towards the cabin roof or up in the payload bay
Post by: elmarko on 12/25/2006 10:57 pm
Post by: cape51 on 12/26/2006 03:59 am
I've been looking on here for documentation concerning the procedure, so if anyone can point me in the right direction, i would appreciate it
Post by: norm103 on 12/26/2006 03:59 am
Post by: northanger on 12/26/2006 03:59 am
Quote
cape51 - 25/12/2006 9:43 PM
Does the shuttle have to wait until SRB sep until it can perform RTLS, or can it disengage earlier?
I've been looking on here for documentation concerning the procedure, so if anyone can point me in the right direction, i would appreciate it
Found this (good graphic at page top).
http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/mission_profile.html#rtls_abort
Post by: landofgrey on 12/26/2006 03:59 am
"Dr. William R. Graham served as NASA Deputy Administrator from November 25, 1985, to December 4, 1985, and as Acting Administrator from December 4, 1985, to May 11, 1986. After the appointment of James Fletcher as NASA Administrator, Dr. Graham served as Deputy Administrator from May 11, 1986, to October 1, 1986. Before joining NASA Dr. Graham was a scientific advisor and consultant to the Reagan Administration. He was also a founder of R&D Associates in the early 1970's. Dr. Graham served as Deputy Administrator for only 9 days before being appointed as NASA' Acting Administrator due to the sudden leave of absence taken by NASA Administrator James Beggs. After serving as Deputy Administrator, Dr. Graham was appointed as Science Advisor to the President in 1986." - NASA
The "sudden leave of absence" of James Beggs was due to two things. First, there was a criminal investigation for corruption that was, in fact, a political move by some powerful people in the Pentagon who wanted Beggs out and "one of their own" in. Beggs was forced out and had to fight the legal battle for years before all charges and allegations were summarily dismissed. Too bad his career was as well. Second, and it relates to the battle with the Pentagon as well, Beggs threatened to resign if Graham was made Deputy Administrator, on the grounds that he wasn't qualified for the job and being qualified was essential (as events a couple months later proved). So, a week after Graham's appointment, Beggs bailed out and focused on his own legal troubles. This is an example of the political garbage that ran rampant over the agency throughout the 70's and 80's, worse in some ways than it is now, and a large peripheral contributor to the Challenger accident and to the inadequate design of some critical systems of the shuttle.
Oh, but to answer your question ha ha ha no, the shuttle can't separate. I guess I diverged a bit with the history lesson.
Post by: cape51 on 12/26/2006 03:59 am
Post by: landofgrey on 12/26/2006 03:59 am
RTLS can be selected anytime after T-0, but nothing is done until after the SRB's separate. That's when all of the prop dump and pitcharound stuff happens. There's no option, no switch or computer command that will either manually or automatically separate the SRB's. The only thing that could would be a destruct command from the RSO, but in that case there'd be no RTLS either.
If there's not enough energy for RTLS or TAL abort then the orbiter would be ditched in the ocean following crew bailout below 50K feet or something like that and if the orbiter is in a stable glide. They'd get the orbiter off the tank and glide down low enough to where they could blow the hatch and pop the slide boom and bailout.
If you want to know who might be able to help, try Mark Kirkman on here. He knows all about that kind of stuff and probably has the procedures in hand already.
Post by: cape51 on 12/26/2006 04:08 am
Post by: northanger on 12/26/2006 04:16 am
What is disengaging earlier? The shuttle? (I'm wondering if I misread your question, hopefully you've figured I'm no expert here. Just curious).
Post by: fdasun on 12/26/2006 05:21 am
Quote
landofgrey - 26/12/2006 12:42 PM
... Sadly funny, Graham PERSONALLY SCRUBBED the STS-51L launch attempt on Jan. 27, 1986 because the weather forecast predicted rain. Instead the weather was perfect and warm and had Challenger not been scrubbed on that day, the accident wouldn't have happened on the 28th...
It might not be his fault. Challenger disaster was doomed to happen, when there were so many mistakes existing in NASA and contractor partners, both technical and management.
By the way, is there any abort operation mode between deorbit burn and landing ? ... ... For many years, we have assumed that re-entry and landing is safe. Nevertheless, after STS-107, TPS safety becomes the most important issue for each flight. Can the orbiter abort its landing process during or after the deorbit burn ? Thanks .
Post by: shuttlefan on 12/26/2006 01:14 pm
Quote
fdasun - 26/12/2006 12:04 AMQuotelandofgrey - 26/12/2006 12:42 PM
... Sadly funny, Graham PERSONALLY SCRUBBED the STS-51L launch attempt on Jan. 27, 1986 because the weather forecast predicted rain. Instead the weather was perfect and warm and had Challenger not been scrubbed on that day, the accident wouldn't have happened on the 28th...
It might not be his fault. Challenger disaster was doomed to happen, when there were so many mistakes existing in NASA and contractor partners, both technical and management.
By the way, is there any abort operation mode between deorbit burn and landing ? ... ... For many years, we have assumed that re-entry and landing is safe. Nevertheless, after STS-107, TPS safety becomes the most important issue for each flight. Can the orbiter abort its landing process during or after the deorbit burn ? Thanks .
No, it cannot abort the landing once the deorbit burn gets underway. Once the Orbital Manuevering System engines begin firing, the orbiter starts slowing down right away, just enough that its orbit will decay in order for it to return to Earth. Once they fire the OMS engines, they are committed to land at a precise time and location. That's why, before the go-for-deorbit-burn is given, the weather at KSC, Edwards, or Northrup must be forecast GO. ;)
Post by: Jim on 12/26/2006 01:35 pm
As mkirk has stated in previous posts, "landing" can be aborted during deorbit burn (and maybe a little after). Another burn is required to put the shuttle back in a stable orbit. Fuel state of the shuttle determines if this is possible.
Also there is a "fast sep" scenario where the orbiter disengages from the ET while the SRB's are still burning. The ability for the orbiter to do this is marginal and some say the orbiter aft attachments (ball joints) would hang up and flip the orbit into the airstream, which would break it up
Post by: elmarko on 12/26/2006 03:05 pm
What happens if one side SRB was burning a little more than the other side, resulting in unequal thrust. You'd get a yawing motion to one side, right? Is there any way to compensate for this?
Post by: Jim on 12/26/2006 03:23 pm
Post by: mkirk on 12/26/2006 04:06 pm
Quote
Jim - 25/12/2006 4:30 PMQuoteelmarko - 25/12/2006 3:55 PM
And also, can someone tell me the plus x stuff in more detail please, because I can never remember which direction X actually is :)
http://spaceflight.nasa.gov/shuttle/reference/index.html
Plus X is towards the cabin roof or up in the payload bay
Let me try and clarify some of the answers and recent questions.
I know Jim actually knows this so I guess he just got the two translation maneuvers confused.
At ET SEP there are normally two translation maneuvers performed a –Z and a +X.
ET SEP occurs at 20 seconds after MECO (main engine cutoff); at structural separation the orbiter’s down firing jets will ignite briefly to initiate a separation from the tank at a rate of 4 feet per second.
The –Z direction is up thru the roof of the cabin or payload bay.
Once the onboard GPCs (general purpose computers) transition the software to Major Mode 104 (the orbital maneuver display) from Major Mode 103 (2nd stage ascent trajectory display) - this transition occurs when the IMUs(inertial measurement units) sense the 4 feet per second acceleration – the Commander will push in on the Translation Controller for 11 seconds to initiate the +X maneuver.
The translation controller (THC) is located on the left side of the cockpit and is used to move the orbiter forward (push in), back (pull out), up/dn (push up/dn), and left/right (push to left or right side). See the attached photo, the THC is the black handle located to the left of the control stick (under the red cover) and above the speed brake handle.
The +X direction is Nose Forward.
The plus X burn allows the cameras in the ET umbilical wells to photograph the length of the fuel tank from bottom to top. It also aids in vehicle separation from the tank and helps set the orbiter up for the ET PHOTO maneuver (which wasn’t done on this last flight since they were in darkness). The ET PHOTO maneuver is a pitch around of the orbiter that allows the crew to take pictures of the tank out of the overhead windows.
Part of the confusion on this subject stems from the fact that the shuttle fly’s in numerous reference frames (or coordinate systems). At MECO the shuttle is in the LVLH (local vertical local horizontal) reference frame which is the most “airplane like” and therefore the most intuitive for the pilots.
Mark Kirkman
Post by: shuttlefan on 12/26/2006 04:25 pm
Quote
elmarko - 26/12/2006 9:48 AM
Speaking of SRBs, I was wondering today, you know how some SRBs burn "hot" and some burn "cold"
What happens if one side SRB was burning a little more than the other side, resulting in unequal thrust. You'd get a yawing motion to one side, right? Is there any way to compensate for this?
Was there not some issue in 1993 that arose with the SRBs, involving some sort of a pressure spike in one SRB , which ocurred on STS-54 in Jan.'93? If so, can someone provide more details on that and how it was resolved. I seem to recall a news report about it, calling it the " 1 minute, 7 second mystery ", because it ocurred 1 minute and 7 seconds into launch.
Post by: mkirk on 12/26/2006 04:27 pm
Quote
fdasun - 26/12/2006 12:04 AM
By the way, is there any abort operation mode between deorbit burn and landing ? ... ... For many years, we have assumed that re-entry and landing is safe. Nevertheless, after STS-107, TPS safety becomes the most important issue for each flight. Can the orbiter abort its landing process during or after the deorbit burn ? Thanks .
Aborting the Deorbit Burn:
The Deorbit Burn can be stopped if the orbiter altitude is above “Safe HP”. HP is the perigee altitude of a given orbit. Safe HP is the altitude that will allow the shuttle to remain in orbit for at least 24 hours before aerodynamic drag effects begin to cause the orbit to decay. For the shuttle this altitude is usually set at 85 nautical miles. This critical altitude is called out in the flight control room on the flight loop and usually PAO will announce it as well.
When the Deorbit OMS burn is underway the crew will watch the HP begin to count down on the Deorbit Maneuver CRT display, if a systems problem occurs prior to going below 85 nm (safe HP) then the burn can be stopped and the problem evaluated. If the orbiter is below Safe HP then the orbiter is committed to Entry.
Mark Kirkman
Post by: elmarko on 12/26/2006 04:43 pm
I have a few other questions whizzing about in my head, but to give someone else a chance, and also so as not to abuse the priviledge, I'll hold off for a few days. Maybe even word them correctly before committing to the submit button :)
Post by: ichilton on 12/26/2006 05:35 pm
Quote
That's why, before the go-for-deorbit-burn is given, the weather at KSC, Edwards, or Northrup must be forecast GO. ;)But what happens if the weather changes between the GO/de-orbit burn and landing, which is about an hour isn't it? - would they just have to land anyway but it would be difficult if the weather turned bad?
Also, at what point does it enter the earths atmosphere (and can burn up like Columbia)? - is that between deorbit burn and landing?
Is there still a radio blackout like the Apollo 13 film?
Thanks
Ian
Post by: Chris Bergin on 12/26/2006 05:44 pm
Quote
ichilton - 26/12/2006 6:18 PM
Is there still a radio blackout like the Apollo 13 film?
Thanks
Ian
Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).
Don't know if the Apollo 13 film grandstanded the "we should have heard from them by now" on the re-entry, or if it happened like that for real.
Post by: elmarko on 12/26/2006 05:57 pm
Post by: bernse on 12/26/2006 06:26 pm
Quote
Chris Bergin - 25/12/2006 11:27 PMAccording to an interview I saw with Jim Lovell, the blackout lasted longer than normal due to them being quite a bit shallower on reentry than planned (quite a bit being relative, I suspect!). So, from this comment he gave I'd say the blackout did last longer than expected.
Don't know if the Apollo 13 film grandstanded the "we should have heard from them by now" on the re-entry, or if it happened like that for real.
Post by: Jim on 12/26/2006 06:39 pm
Post by: Jim on 12/26/2006 06:43 pm
Post by: bernse on 12/26/2006 06:50 pm
Why only "4" flights left? I understand that there are finite lifespans for some of the equipment, but surely they would not simply "fail" if they are flown again, would they? Or, could just the "questionable" equipment get replaced, or even inspected or recertified again as opposed to a full-blown Orbiter overhaul?
Post by: Jim on 12/26/2006 06:57 pm
Quote
bernse - 26/12/2006 2:33 PM
Question about Orbiter retirement. I believe it has been mentioned that Atlantis only has 4 flights left in it before its due for refurbishment, but because of the STS program retirement date, they aren't going to do it.
Why only "4" flights left? I understand that there are finite lifespans for some of the equipment, but surely they would not simply "fail" if they are flown again, would they? Or, could just the "questionable" equipment get replaced, or even inspected or recertified again as opposed to a full-blown Orbiter overhaul?
there is a thread called "4 more flights" that goes into this issue
It isn't just refurbishment, but also detailed structural inspections
Post by: bernse on 12/26/2006 07:04 pm
Post by: DaveS on 12/26/2006 07:29 pm
Quote
elmarko - 26/12/2006 7:40 PMNope. Comm and telemetry is pretty solid throughout entry, except for some minor drops when the tail blocks the view of TDRS-W until MILA can take over.
And don't forget, thanks to TDRS, the comm dropouts aren't anywhere near as long (I guess, anyway...)
Post by: shuttlefan on 12/26/2006 08:14 pm
Quote
Jim - 26/12/2006 8:18 AM
Some corrections
As mkirk has stated in previous posts, "landing" can be aborted during deorbit burn (and maybe a little after). Another burn is required to put the shuttle back in a stable orbit. Fuel state of the shuttle determines if this is possible.
Also there is a "fast sep" scenario where the orbiter disengages from the ET while the SRB's are still burning. The ability for the orbiter to do this is marginal and some say the orbiter aft attachments (ball joints) would hang up and flip the orbit into the airstream, which would break it up
I stand corrected! I didn't know landing can still be aborted after OMS ignition.
Post by: ichilton on 12/26/2006 08:34 pm
Quote
Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).So where abouts is re-entry between the de-orbit burn and landing?
I got home and got NASA TV on half way between the deorbit burn and landing last week but there didn't seem to be any mention of re-entry or a communications break.
Thanks
Ian
Post by: Gary on 12/26/2006 08:37 pm
From that point until about 150,000 the orbiter is in the heat of re-entry and is where it conducts the S-turns to dissapate the energy gained at launch. I'm sure Jim or someone can give you more info than that.
Post by: ichilton on 12/26/2006 08:53 pm
Thanks
Ian
Post by: Jim on 12/26/2006 08:55 pm
Post by: ichilton on 12/26/2006 08:57 pm
What about on STS-116?
Thanks
Ian
Post by: mkirk on 12/26/2006 09:17 pm
Quote
ichilton - 26/12/2006 3:17 PM
So where abouts is re-entry between the de-orbit burn and landing?
Ian
It varies slightly from mission to mission. For STS-116 the Deorbit burn was planned to occur at 4:26:10 pm Eastern. Entry Interface occurred about 34 minutes later at 5:00 pm at a range from the runway of 4,333 nautical miles and an altitude of 399,000 feet. Touchdown was at 5:32 pm. The highest heating occurs in the Mach 24-Mach 16 range (peak heating is generally around Mach 20-19).
The high surface heating begins to occur at about 6 minutes after Entry Interface as the orbiter slows to Mach 24 and descends thru about 250,000 feet.
Mark Kirkman
Post by: gordo on 12/26/2006 10:59 pm
Quote
ichilton - 26/12/2006 9:17 PMQuoteYes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).So where abouts is re-entry between the de-orbit burn and landing?
I got home and got NASA TV on half way between the deorbit burn and landing last week but there didn't seem to be any mention of re-entry or a communications break.
Thanks
Ian
Generally there is full communication now during re-entry, as the Orbiter can still communicate through TDRS, occasionally the orbiters attitude can block the signal, for example the original comms loss on 107 was due to the fin getting in the way.
Post by: fdasun on 12/27/2006 03:16 am
Quote
mkirk - 27/12/2006 1:10 AM
When the Deorbit OMS burn is underway the crew will watch the HP begin to count down on the Deorbit Maneuver CRT display, if a systems problem occurs prior to going below 85 nm (safe HP) then the burn can be stopped and the problem evaluated. If the orbiter is below Safe HP then the orbiter is committed to Entry.
Mark Kirkman
Thanks.
So, may I confirm that there is no abort/rescue/escape option for the crew when the orbiter is under safe HP but above ACES bailout altitude (if I remembered correctly, 15Km is ok for an escape with ACES suit weared) ?
Post by: chksix on 12/27/2006 08:03 am
Quote
Chris Bergin - 26/12/2006 7:27 PMQuoteichilton - 26/12/2006 6:18 PM
Is there still a radio blackout like the Apollo 13 film?
Thanks
Ian
Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).
Don't know if the Apollo 13 film grandstanded the "we should have heard from them by now" on the re-entry, or if it happened like that for real.
Wasn't there an issue with low batteries? They wanted to save them to be sure that the chutes had enough power to deploy. That's why there was silence for longer than usual.
Post by: elmarko on 12/27/2006 11:09 am
Quote
DaveS - 26/12/2006 8:12 PMQuoteelmarko - 26/12/2006 7:40 PMNope. Comm and telemetry is pretty solid throughout entry, except for some minor drops when the tail blocks the view of TDRS-W until MILA can take over.
And don't forget, thanks to TDRS, the comm dropouts aren't anywhere near as long (I guess, anyway...)
Yeah, that was what I was getting at :)
Realistically, is there anywhere else that the antennas could be mounted to give better reliability? Or are they constrained by heating, aerodynamics, etc?
Post by: C5C6 on 12/27/2006 11:22 am
Post by: elmarko on 12/27/2006 11:27 am
Post by: gordo on 12/27/2006 11:44 am
Quote
chksix - 27/12/2006 8:46 AMQuoteChris Bergin - 26/12/2006 7:27 PMQuoteichilton - 26/12/2006 6:18 PM
Is there still a radio blackout like the Apollo 13 film?
Thanks
Ian
Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).
Don't know if the Apollo 13 film grandstanded the "we should have heard from them by now" on the re-entry, or if it happened like that for real.
Wasn't there an issue with low batteries? They wanted to save them to be sure that the chutes had enough power to deploy. That's why there was silence for longer than usual.
Should be in History, but the 90 secs of extra blackout was unexpected. Was due in the end to a shallower approach to re-entry.
Post by: Jim on 12/27/2006 01:30 pm
Quote
chksix - 27/12/2006 3:46 AMQuoteChris Bergin - 26/12/2006 7:27 PMQuoteichilton - 26/12/2006 6:18 PM
Is there still a radio blackout like the Apollo 13 film?
Thanks
Ian
Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).
Don't know if the Apollo 13 film grandstanded the "we should have heard from them by now" on the re-entry, or if it happened like that for real.
Wasn't there an issue with low batteries? They wanted to save them to be sure that the chutes had enough power to deploy. That's why there was silence for longer than usual.
There were separate batteries for ordnance
Post by: Jim on 12/27/2006 01:31 pm
Quote
fdasun - 26/12/2006 10:59 PMQuotemkirk - 27/12/2006 1:10 AM
When the Deorbit OMS burn is underway the crew will watch the HP begin to count down on the Deorbit Maneuver CRT display, if a systems problem occurs prior to going below 85 nm (safe HP) then the burn can be stopped and the problem evaluated. If the orbiter is below Safe HP then the orbiter is committed to Entry.
Mark Kirkman
Thanks.
So, may I confirm that there is no abort/rescue/escape option for the crew when the orbiter is under safe HP but above ACES bailout altitude (if I remembered correctly, 15Km is ok for an escape with ACES suit weared) ?
Bail out is only an option in a stable glide below 50k feet.
Post by: Jim on 12/27/2006 01:32 pm
Quote
elmarko - 27/12/2006 7:10 AM
Actually I've always wondered about that as well. Say you had a particularly sleepless astronaut. Are things like sleeping pills available, or any other remedies to help them sleep? I imagine whatever they took would have to be pretty well controlled and studied for side effects. You don't want a groggy crew member conducting an EVA, for example.
They have no real trouble sleeping, but there are pills available. There have been stories told that towards the end of missions that due to the pace, it is real easy to nod off during moments of inactivity
Post by: shuttlefan on 12/27/2006 01:35 pm
Quote
Jim - 27/12/2006 8:15 AMQuoteelmarko - 27/12/2006 7:10 AM
Actually I've always wondered about that as well. Say you had a particularly sleepless astronaut. Are things like sleeping pills available, or any other remedies to help them sleep? I imagine whatever they took would have to be pretty well controlled and studied for side effects. You don't want a groggy crew member conducting an EVA, for example.
They have no real trouble sleeping
Alot of astronauts will tell you they are so trained and mentally-prepared for any scenario, that they don't even have trouble sleeping the " night " before launch even when the weather is questionable. ;)
Post by: Jim on 12/27/2006 01:37 pm
Quote
elmarko - 27/12/2006 6:52 AM.QuoteDaveS - 26/12/2006 8:12 PMQuoteelmarko - 26/12/2006 7:40 PMNope. Comm and telemetry is pretty solid throughout entry, except for some minor drops when the tail blocks the view of TDRS-W until MILA can take over.
And don't forget, thanks to TDRS, the comm dropouts aren't anywhere near as long (I guess, anyway...)
Yeah, that was what I was getting at :)
Realistically, is there anywhere else that the antennas could be mounted to give better reliability? Or are they constrained by heating, aerodynamics, etc?
There is no issue with reliability or the need for 100% coverage. Orbiters landed before there was the TDRSS and they experienced blackouts.
4 S-band antennas are mounted in quandrants around the crewn cabin under the tiles. Which provides the needed coverage on orbit, launch and entry
Why mod the orbiters now when the program is ending in a few years anyways
Post by: shuttlefan on 12/27/2006 01:39 pm
Post by: Jim on 12/27/2006 01:42 pm
Quote
shuttlefan - 27/12/2006 9:22 AM
If, for example they would ever decide to launch a shuttle from Pad B instead of Pad A, would the computers have to be reprogrammed to fly a slightly different flight profile, or does the pad they are launching from make absolutely no difference?
There are differences. Even for Delta II, whose pads are closer, have to take into account the differences
Post by: dutch courage on 12/27/2006 01:49 pm
Post by: ichilton on 12/27/2006 02:13 pm
Quote
Why mod the orbiters now when the program is ending in a few years anywaysI've seen several references to the shuttles been retired in 2010.
What happens after that? - no more space flights or do they just have a new spacecraft?
Thanks
Ian
Post by: Jim on 12/27/2006 02:24 pm
Post by: C5C6 on 12/27/2006 10:11 pm
Post by: Jorge on 12/27/2006 11:02 pm
Quote
C5C6 - 25/12/2006 2:14 PM
I just wondered, do astronauts use some kind of a drug to sleep? i find it hard to believe that with so much adrenaline flowing they are able to sleep as if everything was normal....is there any training for this issue?
They use melatonin (a natural hormone) to help sleep-shifting, and to keep the biological clock stable in the somewhat unnatural lighting environment of LEO. No artificial sleeping pills, since that would inhibit their performance if they were awakened by an emergency in the middle of crew sleep.
--
JRF
Post by: Jorge on 12/27/2006 11:37 pm
Quote
C5C6 - 27/12/2006 4:54 PM
why doesnt the orbiter dock with the ISS trough the 'place where astronauts enter the vehicle in launch and landing' ?(sorry for the expresion but i dont know its name). that would allow more payload
No docking mechanism there, and no way to mount one without interfering with entry aerodynamics unless you want to tear up and redesign the whole side of the cabin. Moving it there wouldn't allow more payload; the payload bay docking mechanism doubles as an airlock.
--
JRF
Post by: on 12/28/2006 03:08 pm
Quote
Jim - 27/12/2006 8:15 AM
They have no real trouble sleeping, but there are pills available. There have been stories told that towards the end of missions that due to the pace, it is real easy to nod off during moments of inactivity
I can imagine that being weightless it's very easy to just fall asleep wherever / whenever you're not actively engaged in your work.
Post by: shuttlefan on 12/28/2006 04:40 pm
Post by: Jorge on 12/28/2006 06:14 pm
Quote
shuttlefan - 28/12/2006 11:23 AM
With regards to the explosive bolts holding the shuttle to the launch pad, which detonate at launch, does anyone know how thick they are and are they solid steel?
The bolts are 28 inches long and 3.5 inches diameter. Not sure what alloy, probably Jim would know.
Incidentally... technically, they are studs, not bolts, since they are threaded throughout their length and have nuts at both ends rather than one nut and a head. It is actually the upper nut, called a frangible nut, that is explosive, not the studs. The frangible nut has two holes to accept two NASA Standard Initiators (NSIs). When the NSIs detonate, the frangible nut is broken in two and the halves are caught in a blast container. The pre-tensioned stud is propelled downward into a sand-filled stud decelleration stand.
The frangible nut halves are recovered, mounted on wood bases, and presented to the flown crewmembers as souvenirs.
At a couple of launches I attended (96 and 100, I think), the tour guide had a stud with two nuts on it as a prop during the mission briefing. Looks like a barbell and you could get a pretty good workout lifting it.
--
JRF
Post by: Orbiter Obvious on 12/28/2006 06:20 pm
Quote
Jorge - 28/12/2006 6:57 PM
At a couple of launches I attended (96 and 100, I think)
Man, when I get out of school and get some money together, I'm gonna love having a 1 next to my attendance for launches!
Post by: TheMadCap on 12/30/2006 05:04 pm
Question regarding the zinc chromate putty in the field joints of the SRBs. The putty seals cracks in the connection between two cases, so it does in fact have to come into contact with exhaust gases?
How can this putty stand up to the heat and pressures involved?
Post by: shuttlefan on 12/31/2006 12:18 am
Quote
Jim - 27/12/2006 8:25 AMDo the General Purpose Computers have to be programmed differently depending on which pad they are flying from? (I guess I should use the word ' did ' in place of the word ' do ' , since Pad B will not support any more shuttle launches, Heaven forbid a rescue flight to a Hubble mission.) ;)Quoteshuttlefan - 27/12/2006 9:22 AM
If, for example they would ever decide to launch a shuttle from Pad B instead of Pad A, would the computers have to be reprogrammed to fly a slightly different flight profile, or does the pad they are launching from make absolutely no difference?
There are differences. Even for Delta II, whose pads are closer, have to take into account the differences
Post by: MKremer on 12/31/2006 03:00 am
Quote
shuttlefan - 30/12/2006 7:01 PMDo the General Purpose Computers have to be programmed differently depending on which pad they are flying from? (I guess I should use the word ' did ' in place of the word ' do ' , since Pad B will not support any more shuttle launches, Heaven forbid a rescue flight to a Hubble mission.) ;)[/QUOTE]
There are differences. Even for Delta II, whose pads are closer, have to take into account the differences
Not so much the "pad" as it is the exact initial long/lat position of the LV when calculating the vectors at launch for the preferred initial orbit.
Post by: steve_slitheen on 12/31/2006 11:21 am
Steve.
Post by: dninness on 12/31/2006 01:04 pm
Quote
landofgrey - 25/12/2006 11:42 PM
[snip]
RTLS can be selected anytime after T-0, but nothing is done until after the SRB's separate. That's when all of the prop dump and pitcharound stuff happens. There's no option, no switch or computer command that will either manually or automatically separate the SRB's. The only thing that could would be a destruct command from the RSO, but in that case there'd be no RTLS either.
[snip]
If you want to know who might be able to help, try Mark Kirkman on here. He knows all about that kind of stuff and probably has the procedures in hand already.
I don't want to sound like a pendantic knucklehead, and my only knowledge of this comes from a REALLY out of date reference ("The Space Shuttle Operators Manual"..tee heee), but what about the "ET SEP" and "SRB SEP" push switches on the center console? I am reasonably certain that pressing either set of buttons during the first stage would be the textbook definition of a "bad day," but I know they're there. Maybe Mark can tell us if they are locked out during that MM or not.
Thanks!
Darin
Post by: shuttlefan on 12/31/2006 01:37 pm
Quote
dninness - 31/12/2006 7:47 AMTrying to seperate from the ET during SRB first-stage burn would almost-certainly be fatal. If the white-hote flame plume from the SRBs don't burn the orbiter severely, it will almost certainly be sent into an uncontrollable spiral by the SRBs. :o :oQuotelandofgrey - 25/12/2006 11:42 PM
[snip]
RTLS can be selected anytime after T-0, but nothing is done until after the SRB's separate. That's when all of the prop dump and pitcharound stuff happens. There's no option, no switch or computer command that will either manually or automatically separate the SRB's. The only thing that could would be a destruct command from the RSO, but in that case there'd be no RTLS either.
[snip]
If you want to know who might be able to help, try Mark Kirkman on here. He knows all about that kind of stuff and probably has the procedures in hand already.
I don't want to sound like a pendantic knucklehead, and my only knowledge of this comes from a REALLY out of date reference ("The Space Shuttle Operators Manual"..tee heee), but what about the "ET SEP" and "SRB SEP" push switches on the center console? I am reasonably certain that pressing either set of buttons during the first stage would be the textbook definition of a "bad day," but I know they're there. Maybe Mark can tell us if they are locked out during that MM or not.
Thanks!
Darin
Post by: Jim on 12/31/2006 02:13 pm
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steve_slitheen - 31/12/2006 7:04 AM
Why do the orbiters have dummy RCS and OMS pods for 747 ferry flights? Why not leave the real things in place?
Steve.
If the ferry flight is for a EAFB landing, the real ones are in place. But if it the orbiter was at Palmdale for refurbishment, the pods sometimes stayed at KSC.
Post by: Jim on 12/31/2006 02:43 pm
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dninness - 31/12/2006 8:47 AMQuotelandofgrey - 25/12/2006 11:42 PM
[snip]
RTLS can be selected anytime after T-0, but nothing is done until after the SRB's separate. That's when all of the prop dump and pitcharound stuff happens. There's no option, no switch or computer command that will either manually or automatically separate the SRB's. The only thing that could would be a destruct command from the RSO, but in that case there'd be no RTLS either.
[snip]
If you want to know who might be able to help, try Mark Kirkman on here. He knows all about that kind of stuff and probably has the procedures in hand already.
I don't want to sound like a pendantic knucklehead, and my only knowledge of this comes from a REALLY out of date reference ("The Space Shuttle Operators Manual"..tee heee), but what about the "ET SEP" and "SRB SEP" push switches on the center console? I am reasonably certain that pressing either set of buttons during the first stage would be the textbook definition of a "bad day," but I know they're there. Maybe Mark can tell us if they are locked out during that MM or not.
Thanks!
Darin
ET SEP is not locked out during ascent. there is a "fast sep" abort scenario (however unlikely)
Post by: Jim on 12/31/2006 02:44 pm
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TheMadCap - 30/12/2006 12:47 PM
I don't think anyone answered this one:
Question regarding the zinc chromate putty in the field joints of the SRBs. The putty seals cracks in the connection between two cases, so it does in fact have to come into contact with exhaust gases?
How can this putty stand up to the heat and pressures involved?
The SRM burns from the inside outward.
Post by: TheMadCap on 12/31/2006 07:15 pm
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Jim - 31/12/2006 9:27 AMQuoteTheMadCap - 30/12/2006 12:47 PM
I don't think anyone answered this one:
Question regarding the zinc chromate putty in the field joints of the SRBs. The putty seals cracks in the connection between two cases, so it does in fact have to come into contact with exhaust gases?
How can this putty stand up to the heat and pressures involved?
The SRM burns from the inside outward.
OF course, duh huh! And since the less fuel remaining, the less thrust and pressure, it helps the seal stay intact as well, correct?
Post by: Jim on 12/31/2006 07:53 pm
* for this example, the actual thrust vs time curve doesn't matter
Post by: TJL on 12/31/2006 11:55 pm
Chart can be viewed here: http://collectspace.com/review/sts115_ssmechart-lg.jpg
Post by: James Lowe1 on 12/31/2006 11:58 pm
Post by: psloss on 01/01/2007 12:30 am
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TJL - 31/12/2006 7:38 PMDifferent powerheads, according to the chart. It's listed as 2038 / 2048 using the 6007 powerhead through STS-95 (October, 1998), and then listed as 2048 using powerhead 6021 beginning with STS-92 (October, 2000).
On the Pratt & Whitney (SSME) chart it seems that all Block 2 engines are being used except SSME # 2048 which was last flown in October 1998 on STS-95. Was that engine retired?
Chart can be viewed here: http://collectspace.com/review/sts115_ssmechart-lg.jpg
(Note that the 2038 / 2048 engine with the 6007 powerhead is not listed as active.)
Post by: TJL on 01/01/2007 01:32 am
Post by: Felonator on 01/03/2007 07:25 pm
Thanks
Mike
Post by: kneecaps on 01/03/2007 07:53 pm
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Felonator - 3/1/2007 8:08 PM
I have a question. I have searched the forums to make sure i aint asking same question, so sory if i am. :) At what speed during the landing stage do all the control surfaces become usable? And does the control stick feedback to the pilot? or does he/she just feel a dead stick? Hope they arnt stupid questions for the shuttle geniuses on here :)
Thanks
Mike
Hi and welcome!
The orbiters aerosurfaces (or control surfaces) become active at different points during Entry. At EI (Entry Interface ~400k ft), the RCS provides control in all axes. During entry as dynamic pressure (q-bar) increases during entry various aerosurfaces are 'blended' in as they are able to provide more control authority than the RCS. Various documents (SCOM , Shuttle Crew Operations Manual) can give you more info but the first initial aerosurface control begins at about EI+3:00 (Entry Interface + 3:00 mins) and the surfaces are elevons and ailerons. By EI +28:00 the RCS Yaw jets are deactivated, these are the last jets to be deactivated in the Entry so at this point the aerosurfaces have total control.
No, there is no 'feedback' to the pilot from the stick besides its physical position, its totally fly by wire and sitck deflections are monitored by microswitches, probably feels much like a standard computer joystick prehaps.
I'm just an armchair astronaut but I'm sure somebody will jump in with some better info on this for you.
Pete
Post by: Felonator on 01/03/2007 08:07 pm
As for the control stick that must feel extremely odd for someone that has flown aircraft for along time. or not?? Does the STA simulate this too?
Cheers again
Mike
Post by: mainengine on 01/03/2007 08:18 pm
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TJL - 31/12/2006 8:15 PM
psloss..I missed that..thank you. So, Powerhead # 6007 is no longer active.
Since this chart is actual a powerhead chart it is a little bit confusing.
Besides there were 47 engines flown on the shuttle in the 115 launches mentioned (look at the engine chart).
Post by: kneecaps on 01/03/2007 08:33 pm
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Felonator - 3/1/2007 8:50 PM
WOW! thanks for that Pete. Answers alot of questions :) Does anyone have a idea about the actual speed? Or guess at the mach number? I have messed with a supersonic wind tunnel and the force needed to move a control surface is unbelievable.
As for the control stick that must feel extremely odd for someone that has flown aircraft for along time. or not?? Does the STA simulate this too?
Cheers again
Mike
Most modern aircraft high performance aircraft are fly by wire, but having flown various aircraft (none fly by wire though!) you tend to adapt pretty quickly to the feel of the stick, think about driving a car (if you do and its manual, ('stick-shift' for our American friends), it doesn't take long to get used to operating a different clutch.
If you have the SCOM look at section 5.4-6 it gives a breakdown of the mach numbers and what happens when. If not here they are:
+2:39 -29:35 Automatic elevon trim begins at a q-bar = 0.5 psf.
+3:32 -28:42 Aerosurface control begins at q-bar = 2.0 psf. CDR, PLT monitor elevon and aileron deflection angles on surface position indicator
+5:00 27:14 Roll RCS jets deactivated at q-bar = 10 psf.
+8:04 -24:10 Pitch RCS jets deactivated at q-bar = 40.
+20:03 -12:11 VREL=10 k fps
(Mach = 10) Alt = 150 k ft Speedbrake opens to 81 percent
+27:53 -04:21 (Mach = 1.0) Alt = 54 k ft RCS yaw jets are deactivated.
Some of the data sheets over at Bill Harwoods CBS pages show entry velocity, time info, so you could cross reference with these.
Post by: Felonator on 01/03/2007 09:08 pm
And again that leads me onto the STA, i take it that is all fly by wire so its exactly the same to the shutle??
Cheers again :)
Post by: Jorge on 01/03/2007 09:18 pm
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kneecaps - 3/1/2007 2:36 PMQuoteFelonator - 3/1/2007 8:08 PM
And does the control stick feedback to the pilot? or does he/she just feel a dead stick?
No, there is no 'feedback' to the pilot from the stick besides its physical position, its totally fly by wire and sitck deflections are monitored by microswitches, probably feels much like a standard computer joystick prehaps.
The Rotational Hand Controller (RHC) is an analog controller, not digital, so it uses potentiometers, not microswitches, to measure stick deflection. (Technically, there are microswitches in it but they are used for BFS engage, trim, PTT, etc, not flying). Like a PC joystick, the RHC has centering springs that provide increasing resistance to larger deflections: 1.45 in-lb per deg in pitch, 2.1 in-lb per degree in roll, and 0.7 in-lb per degree in yaw.
The Translational Hand Controller (THC) is digital and does use microswitches, but it's not used during entry.
--
JRF
Post by: Felonator on 01/03/2007 09:24 pm
Thanks again :)
Post by: Jorge on 01/03/2007 09:29 pm
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Felonator - 3/1/2007 4:07 PM
Excellent. Thanks for that Jorge. So there is some resistance. That would defo help to control it IMO. Kinda like a Force Feedback stick or not to that extreme? LOL sorry if noone has a clue. dont want to ask impossible questions.
Thanks again :)
Just to clarify, the resistance is purely a function of deflection, it's not any kind of actual force feedback from the control surfaces.
--
JRF
Post by: Felonator on 01/03/2007 09:36 pm
Just to clarify, the resistance is purely a function of deflection, it's not any kind of actual force feedback from the control surfaces.
--
JRF[/QUOTE]
Could you expand on that. Some of the terms i dont think i am 100% on. I understand that nothing is fed back to the pilot through the stick but there is a force applied against the pilots controls. Is that just to "center" it? Or from your answer before i understood it as, the more the angle of pitch, roll or yaw applied the harder the force applied back to the pilot. Is this to help simulate feedback through the controls?
Thanks again and sorry to keep askin ;)
Post by: kneecaps on 01/03/2007 09:44 pm
JRF[/QUOTE]
Could you expand on that. Some of the terms i dont think i am 100% on. I understand that nothing is fed back to the pilot through the stick but there is a force applied against the pilots controls. Is that just to "center" it? Or from your answer before i understood it as, the more the angle of pitch, roll or yaw applied the harded the force applied back to the pilot. Is this to help simulate feedback through the controls?
Thanks again and sorry to keep askin ;)[/QUOTE]
Its fine!
From what I can see of its design/construction it wouldn't feel much different to any other stick, probably better if anything. It doesn't seem to have much 'travel' compared with a aircraft though.
Post by: Jorge on 01/03/2007 09:58 pm
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Felonator - 3/1/2007 4:19 PM
Just to clarify, the resistance is purely a function of deflection, it's not any kind of actual force feedback from the control surfaces.
--
JRF[/QUOTE]
Could you expand on that. Some of the terms i dont think i am 100% on. I understand that nothing is fed back to the pilot through the stick but there is a force applied against the pilots controls. Is that just to "center" it? Or from your answer before i understood it as, the more the angle of pitch, roll or yaw applied the harder the force applied back to the pilot. Is this to help simulate feedback through the controls?
Thanks again and sorry to keep askin ;)[/QUOTE]
It's ok, I could be more clear with my answers. The pitch, yaw, and roll in question are hand controller axes, not vehicle axes. The torque is applied to center the stick, but the amount torque varies by hand controller axis.
--
JRF
Post by: Felonator on 01/03/2007 10:18 pm
http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts-rhc.html
Now the only question as of yet is...... And i hope i make sense as i just write as i think it.
You were talking about the axis of the rotational hand controller. Now as i understand it there are three yeah? and this "Yaw" imput that your talkin about, is this imputed by a twist of the stick? like clockwise/counter clock wise by a few degrees? and also is this just for the OMS. Which to be honest would make sense. But as for the Landing stage. This yaw imput into the RHC (ie twist of the wrist) if thats correct is only used until as Kneecaps informed me before "+27:53 -04:21 (Mach = 1.0) Alt = 54 k ft RCS yaw jets are deactivated." and at this stage do the rudder pedals become usable for controlling yaw.
Let us know if i need to ask my questions in a more infomed way. As i am trying to learn so much its easy for me to wonder off to something that totally might not make sense.
oh and cheers again :)
Post by: Jorge on 01/03/2007 11:24 pm
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Felonator - 3/1/2007 5:01 PM
You were talking about the axis of the rotational hand controller. Now as i understand it there are three yeah? and this "Yaw" imput that your talkin about, is this imputed by a twist of the stick? like clockwise/counter clock wise by a few degrees?
That's right, the RHC has three axes, and yaw corresponds to clockwise/counterclockwise twist of the stick.
Quote
and also is this just for the OMS. Which to be honest would make sense. But as for the Landing stage. This yaw imput into the RHC (ie twist of the wrist) if thats correct is only used until as Kneecaps informed me before "+27:53 -04:21 (Mach = 1.0) Alt = 54 k ft RCS yaw jets are deactivated." and at this stage do the rudder pedals become usable for controlling yaw.
The behavior of the RHC does depend on phase of flight. During powered flight, all three axes are available when manual control is selected. RHC inputs are used to control the SSME and SRB gimbals. Manual control during ascent has never been done in flight, and Flight Rules forbid it prior to 90 seconds after launch.
In orbit, all three axes are available when manual control is selected. RHC inputs are used to control the RCS jets, or the OMS gimbals when an OMS firing is in progress.
During entry, only RHC pitch/roll is available. The Entry Digital Auto Pilot (DAP) provides automatic turn coordination so that yaw inputs should not be necessary for banking maneuvers, though the rudder pedals become active for yaw control below Mach 5. RHC inputs are used either to fire RCS jets or deflect aerosurfaces, according to the qbar/Mach milestones posted earlier.
After touchdown, the rudder pedals are used to control nose wheel steering and brakes.
--
JRF
Post by: Felonator on 01/03/2007 11:56 pm
Post by: MySDCUserID on 01/04/2007 01:34 am
Post by: DaveS on 01/04/2007 01:41 am
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kneecaps - 3/1/2007 9:36 PMThere are no such things as ailerons on the orbiter. The elevons are combined elevators and ailerons.
and the surfaces are elevons and ailerons.
Post by: Jim on 01/04/2007 01:43 am
The ARF is on KSC
Post by: Crispy on 01/04/2007 10:10 pm
Post by: mkirk on 01/04/2007 10:51 pm
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Crispy - 4/1/2007 4:53 PM
Manual control of SSME gimballing! O_O Is there actually a set of circumstances where that would be a good idea?
I’m not sure I completely understand your question, but during second stage the SSME Thrust Vector Control is what maneuvers the vehicle (orbiter & ET). First stage control comes primarily from the SRB Nozzles.
Manual control (if required) via the RHC (rotational hand controller or “stick”) is NOT RECOMMENDED until about 90 second into the flight. This is because there is no method in place for the crew to manage "load relief". Load relief is a flight control scheme that is used to mange the aerodynamic/structural loads on the vehicle by positioning the flight controls (differentially). In other words you don’t want to rip the wings off and the Commander and Pilot have no feedback within the system that allows them to control vehicle loads during the transition thru the lower atmosphere.
As Jorge said in an earlier post, manual control is possible after the 90 second point and in second stage (i.e. after SRB SEP) with the RHC. In the SMS (shuttle mission simulator) I found the orbiter to be very responsive and precise going up hill. You can really point the orbiter where you want it and it will stay there because of the “rate command/attitude hold” flight control mode. It takes very small control inputs and assuming guidance & nav are working correctly (which is probably not the case if you had to take over manual control during ascent) it is simply a matter of centering the guidance needles on the ADI (attitude indicator or “8 ball”). You have a roll needle on the top, pitch needle on the right side, and a yaw needle on the bottom…you simply center the needles like a set of cross hairs by pointing the RHC in the direction of the particular needle. As mentioned earlier yaw is controlled by rotating/twisting the RHC to the left or right
The RHC inputs during ascent go through the DAP (digital auto pilot) and are sent out as commands to position the SSME gimbal actuators. Should roll control using this method be lost due to 2 failed engines or failed actuators for 2 of the 3 engines then a scheme called SERC (single engine roll control) will be invoked which allows the RCS jets to augment the single remaining (gimballing) engine.
Mark Kirkman
Post by: shuttlefan on 01/04/2007 11:52 pm
Post by: STS-500Cmdr on 01/05/2007 06:21 am
Post by: spaceshuttle on 01/05/2007 06:38 am
Post by: C5C6 on 01/05/2007 01:50 pm
Post by: Jim on 01/05/2007 01:59 pm
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C5C6 - 5/1/2007 9:33 AM
can somebody show me an image that shows the exact points where the shuttle is attached to the MLP??? i still dont know that and cant imagine how the shuttle remains still and doesnt fall to a side.....thank you so much :)
Four points on the base of each SRB. Just like they are attached to the yellow GSE stands
Post by: C5C6 on 01/05/2007 04:55 pm
Post by: DaveS on 01/05/2007 05:03 pm
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C5C6 - 5/1/2007 6:38 PMYes there is. That's why NASA has wind rules for the Space Shuttle Vehicle(SSV) when it's out at the pad. If winds are expected to exceed 65 kts, the SSV will have to be rolled off the pad into the protective environment of the VAB.
thank you so much jim!! anyway, those 8 points must resist the entire shuttle weight, and oscillation caused by winds......isnt there the possibility of the shuttle falling to a side??
Just browse through the Atlantis forum (http://forum.nasaspaceflight.com/forums/forum-view.asp?fid=3) and check out the STS-115 pad processing threads for more info on this.
Post by: Jim on 01/05/2007 05:43 pm
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C5C6 - 5/1/2007 12:38 PM
thank you so much jim!! anyway, those 8 points must resist the entire shuttle weight, and oscillation caused by winds......isnt there the possibility of the shuttle falling to a side??
They also have to withstand the thrust of the SSME's (1.2 million lbs thrust) for more than 3 seconds before the SRB's are lit and the holddown bolts fired. Winds aren't the driving factor
Post by: DaveS on 01/06/2007 02:40 am
Post by: shuttlefan on 01/10/2007 09:53 pm
Post by: Jim on 01/10/2007 10:29 pm
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shuttlefan - 10/1/2007 5:36 PM
How come the Commander no longer makes the " Pc less than 50, Houston " call just before SRB sep.?
Because there is nothing anybody can do about it
Post by: elmarko on 01/11/2007 01:14 am
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Jim - 10/1/2007 11:12 PMQuoteshuttlefan - 10/1/2007 5:36 PM
How come the Commander no longer makes the " Pc less than 50, Houston " call just before SRB sep.?
Because there is nothing anybody can do about it
There are other calls that seem to have disappeared or appeared over the years.
Like, "Performance nominal" - I don't recall hearing that anymore. Heard it on the STS-93 video.
I think it was on STS-112, after MECO there was something called up that I didn't quite hear: "We saw
Also, what is the "nominal shutdown plan" ? - I've heard it called by CAPCOM and CDR on different flights, but years ago we never heard it (I think). And what is an off-nominal shutdown case in this context?
Post by: Jim on 01/11/2007 01:29 am
They only will call off nominal
-------I think it was on STS-112, after MECO there was something called up that I didn't quite hear: "We saw
Some caution and warning alert that didn't require crew action
---- Also, what is the "nominal shutdown plan" ? - I've heard it called by CAPCOM and CDR on different flights, but years ago we never heard it (I think). And what is an off-nominal shutdown case in this context?
APU shutdown per nominal time on the ascent checklist
mkirk will correct me if I am off
Post by: MKremer on 01/11/2007 02:04 am
- what equipment is used to align each SRB both vertically, and with each other, during or after stacking?
- how are the upper attach points aligned to their designated ET so they mate precisely, and how are they fine-adjusted (either at the SRB frustrom/MLP base supports or otherwise)?
(I'm assuming that since the lower attachments are mostly concerned with counteracting side forces they have a bit more alignment 'freedom' available for mating.)
Post by: DaveS on 01/11/2007 11:16 pm
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elmarko - 11/1/2007 2:57 AMThis is what was said: CAPCOM: We saw a nominal MECO, OMS-1 not required. We saw L4D fail off, no action.
I think it was on STS-112, after MECO there was something called up that I didn't quite hear: "We saw... no action" - What was this?
Post by: psloss on 01/11/2007 11:35 pm
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elmarko - 10/1/2007 8:57 PMMark (mkirk) already answered this in a L2 thread about STS-112 -- use the search function here and search for posts by mkirk with the words "shutdown plan"
Also, what is the "nominal shutdown plan" ? - I've heard it called by CAPCOM and CDR on different flights, but years ago we never heard it (I think). And what is an off-nominal shutdown case in this context?
Post by: shuttlefan on 01/12/2007 12:50 am
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elmarko - 10/1/2007 7:57 PMQuoteJim - 10/1/2007 11:12 PMQuoteshuttlefan - 10/1/2007 5:36 PM
How come the Commander no longer makes the " Pc less than 50, Houston " call just before SRB sep.?
Because there is nothing anybody can do about it
There are other calls that seem to have disappeared or appeared over the years.
Like, "Performance nominal" - I don't recall hearing that anymore. Heard it on the STS-93 video.
I think it was on STS-112, after MECO there was something called up that I didn't quite hear: "We saw... no action" - What was this?
Also, what is the "nominal shutdown plan" ? - I've heard it called by CAPCOM and CDR on different flights, but years ago we never heard it (I think). And what is an off-nominal shutdown case in this context?
On the first four test flights of Columbia, do you recall the call " Columbia, negative seats "? That meant that they were too high to use the ejection seats, which were only installed for the first 4 flights.
Post by: elmarko on 01/12/2007 08:39 am
PSloss: Roger, will do.
Post by: mkirk on 01/12/2007 07:52 pm
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elmarko - 12/1/2007 3:22 AM
Yep, indeed :) What was the max altitude for them again?
PSloss: Roger, will do.
"Negative Seats" was at 140,000 feet...If I remember correctly.
In response to your question about the shutdown plan, it is NOT related to the APUs. This is a call made during the final minute of powered flight that ensures both the Mission Control Center and the Crew agree that no "off nominal" SSME shutdown procedures are required. Helium Leaks, Hydraulic Failures, Data and Command Path Failures, and Abort Mode are some of the things that can affect the way the main engines need to be shutdown. The call is made about a minute prior to MECO mainly because nobody likes to make last minute changes to the “game plan” going into MECO. This is primarily do to crew work load concerns.
The performance call (such as "Performance Low", Nominal, or High) is only made when necessary. The crew assumes performance is nominal unless they are told otherwise. Again the philosophy is to keep the chatter to a minimum and not garbage up the comm. If performance is low than you will here this call made to ensure the crew is aware of the implications of additional system failures. With low performance and other system failures/leaks there is a chance of a low level cutoff...which actually occured right at MECO on STS-93.
Mark Kirkman
Post by: Skinny on 01/14/2007 12:51 am
Shuttle Q&A Part 3 (http://forum.nasaspaceflight.com/index.php?topic=6156)