-
#960
by
psloss
on 07 May, 2008 19:59
-
Lawntonlookirs - 7/5/2008 3:53 PM
I am still having a problem finding information on the PCR and the PGHM. Do we have any pictures that show the PGHM in operation?
I would suggest this: go to the
Kennedy Media Gallery and search on the acronym. I know there are at least a few pictures in there...
-
#961
by
padrat
on 08 May, 2008 10:11
-
Lawntonlookirs - 7/5/2008 3:53 PM
I am still having a problem finding information on the PCR and the PGHM. Do we have any pictures that show the PGHM in operation?
Let me look in some of my pics at home. I've got some from earlier missions (around STS 121) of inside the PCR. Haven't been able to take any recent ones though since they stopped letting us bring cameras inside the PCR about a year or so ago.
-
#962
by
brahmanknight
on 08 May, 2008 13:54
-
If two shuttles are in orbit at the same time ( such as a LON situation ), are there any problems with coverage from TDRSS? Can it handle that?
-
#963
by
rdale
on 08 May, 2008 14:13
-
In a LON situation, the shuttle is docked to ISS for an extended period so there wouldn't be much of a need for it to comminicate separate from ISS's comm links. For HST, I'm sure there would be some reduction in TDRSS coverage (recall the ATV switching) but I can't imagine it would be crippling.
-
#964
by
psloss
on 08 May, 2008 14:55
-
brahmanknight - 8/5/2008 9:54 AM
If two shuttles are in orbit at the same time ( such as a LON situation ), are there any problems with coverage from TDRSS? Can it handle that?
I believe so, but that's only a possibility for STS-125. It's unlikely that two orbiters would be in orbit together in the ISS CSCS scenario -- the "crippled" orbiter would need to be de-orbited before its consumables ran out and that's likely well before the LON orbiter would be launched.
-
#965
by
Lawntonlookirs
on 08 May, 2008 15:16
-
psloss - 7/5/2008 3:59 PM
Lawntonlookirs - 7/5/2008 3:53 PM
I am still having a problem finding information on the PCR and the PGHM. Do we have any pictures that show the PGHM in operation?
I would suggest this: go to the Kennedy Media Gallery and search on the acronym. I know there are at least a few pictures in there...
Thanks for the advise. I did go into the Kennedy Media Gallery and searched for PGHM and found some interesting information. I guess because of the tight quarters, it is hard to get a full length picture of it. It looks a giant fork lift with adjustable forks.
-
#966
by
Lee Jay
on 08 May, 2008 15:25
-
Try a search for "PCR".
-
#967
by
Jim
on 08 May, 2008 15:37
-
brahmanknight - 8/5/2008 9:54 AM
If two shuttles are in orbit at the same time ( such as a LON situation ), are there any problems with coverage from TDRSS? Can it handle that?
there are many spacecraft in orbit using TDRSS, not just the ISS and shuttles.
-
#968
by
DaveS
on 10 May, 2008 22:38
-
What is the operational capabilities(such as pan/tilt angles, speed and maximum zoom) of the OTV cameras mounted on the MLPs?
-
#969
by
Danny Dot
on 14 May, 2008 03:28
-
I just finished a conversation with an engineer that retired from NASA in 1990. He firmly believes that Eileen Collins performed a BFS engage on ascent during STS-114. I don't think this happened, but this guy really knows his stuff. Did something happen regarding BFS on this flight?
-
#970
by
Jorge
on 14 May, 2008 03:41
-
Danny Dot - 13/5/2008 10:28 PM
I just finished a conversation with an engineer that retired from NASA in 1990. He firmly believes that Eileen Collins performed a BFS engage on ascent during STS-114. I don't think this happened, but this guy really knows his stuff. Did something happen regarding BFS on this flight?
No, he's full of BS.
-
#971
by
Danny Dot
on 14 May, 2008 03:48
-
While working at NASA as an instructor around 1995, I discovered that an SSME nozzle leak of the right size could be detected by the booster flight control team, but the level could not be determined for the purpose of having the Flight Dynamics Officer, FDO, update the Abort Region Determinator, ARD. I made it a point to make sure this nozzle leak issue was well trained.
I just finished listening to the STS-93 audio loops (see link below) and didn't hear the booster flight controller letting the flight director or the FDO know about the potential of a massive performance loss. If STS-93 lost an engine, they might have done an Abort To Orbit, ATO, and ended up too fast for a TAL and too slow to continue the abort to orbit or once around.
Is there anyone reading this post that knows the current status of training an uncalled nozzle leak? A potential loss of hundreds of feet/sec of performance should make the flight loop and this didn't happen on STS-93.
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=6817&posts=120&start=1
-
#972
by
psloss
on 14 May, 2008 10:20
-
Danny Dot - 13/5/2008 11:48 PM
Is there anyone reading this post that knows the current status of training an uncalled nozzle leak? A potential loss of hundreds of feet/sec of performance should make the flight loop and this didn't happen on STS-93.
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=6817&posts=120&start=1
The underspeed from the leak was only like 13-14 fps; hundreds of feet per second would be a completely different ball game.
-
#973
by
Danny Dot
on 14 May, 2008 12:51
-
psloss - 14/5/2008 5:20 AM
Danny Dot - 13/5/2008 11:48 PM
Is there anyone reading this post that knows the current status of training an uncalled nozzle leak? A potential loss of hundreds of feet/sec of performance should make the flight loop and this didn't happen on STS-93.
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=6817&posts=120&start=1
The underspeed from the leak was only like 13-14 fps; hundreds of feet per second would be a completely different ball game.
This 13-14 ft/sec was the underspeed. The delta V loss would be the performance margin added to the underspeed and I understand STS-93 had about 700 feet/second of performance margin. In other words, on a 2 sigma bad day if the engines would not have been turned off by guidance the fuel would have taken the shuttle to an additional 700 feet/sec before running out.
-
#974
by
psloss
on 14 May, 2008 13:46
-
Danny Dot - 14/5/2008 8:51 AM
This 13-14 ft/sec was the underspeed. The delta V loss would be the performance margin added to the underspeed and I understand STS-93 had about 700 feet/second of performance margin. In other words, on a 2 sigma bad day if the engines would not have been turned off by guidance the fuel would have taken the shuttle to an additional 700 feet/sec before running out.
If you have L2 access, there's a thread there, too.
Question: how much of a hypothetical performance issue would be due to dispersions in parameters besides the ones that were indicated by that engine's performance? I would presume that the data as a whole (in the absence of an engine data path issue) would allow some additional insight.
-
#975
by
mkirk
on 14 May, 2008 15:12
-
Danny Dot - 14/5/2008 7:51 AM
psloss - 14/5/2008 5:20 AM
Danny Dot - 13/5/2008 11:48 PM
Is there anyone reading this post that knows the current status of training an uncalled nozzle leak? A potential loss of hundreds of feet/sec of performance should make the flight loop and this didn't happen on STS-93.
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=6817&posts=120&start=1
The underspeed from the leak was only like 13-14 fps; hundreds of feet per second would be a completely different ball game.
This 13-14 ft/sec was the underspeed. The delta V loss would be the performance margin added to the underspeed and I understand STS-93 had about 700 feet/second of performance margin. In other words, on a 2 sigma bad day if the engines would not have been turned off by guidance the fuel would have taken the shuttle to an additional 700 feet/sec before running out.
I don’t know about now, but at the time we immediately began to reassess performance cases and the Flight Rules concerning the ARD limits. MOD and the Training Division began to look at how we could gain more insight into performance hits such as this and naturally such cases were "en vogue" when it came to integrated simulations.
The LH2 leak on 93 was so small that it was below the ARD and Flight Rule limits used at that time.
I’m not sure what you are saying regarding the performance margin but the ~15 foot per second underspeed was a result of the LH2 leak and the resulting Lox Low Level Cutoff right at MECO. Performance Margin is based on the excess amount of LO2 above what is needed to achieve the nominal MECO targets…in this case we ran out of LO2 just prior to Nominal MECO.
Mark Kirkman
-
#976
by
mkirk
on 14 May, 2008 15:22
-
Jorge - 13/5/2008 10:41 PM
Danny Dot - 13/5/2008 10:28 PM
I just finished a conversation with an engineer that retired from NASA in 1990. He firmly believes that Eileen Collins performed a BFS engage on ascent during STS-114. I don't think this happened, but this guy really knows his stuff. Did something happen regarding BFS on this flight?
No, he's full of BS.
The BFS (backup flight system)/BFC (backup flight controller) was not engaged on Ascent!!!!!
The person who told you this may have been confused by discussions noting the change from the primary to the backup flight controllers on the Space Shuttle Main Engine Controllers (DCUs or Digital Computer Units).
We lossed DCU A on the Center Engine and DCU B on the Right Engine. He may have confused the GPC (General Purpose Computer) BFC/BFS with the Main Engine Controller redundant back ups.
Mark Kirkman
-
#977
by
Jorge
on 14 May, 2008 15:40
-
mkirk - 14/5/2008 10:22 AM
Jorge - 13/5/2008 10:41 PM
Danny Dot - 13/5/2008 10:28 PM
I just finished a conversation with an engineer that retired from NASA in 1990. He firmly believes that Eileen Collins performed a BFS engage on ascent during STS-114. I don't think this happened, but this guy really knows his stuff. Did something happen regarding BFS on this flight?
No, he's full of BS.
The BFS (backup flight system)/BFC (backup flight controller) was not engaged on Ascent!!!!!
The person who told you this may have been confused by discussions noting the change from the primary to the backup flight controllers on the Space Shuttle Main Engine Controllers (DCUs or Digital Computer Units).
We lossed DCU A on the Center Engine and DCU B on the Right Engine. He may have confused the GPC (General Purpose Computer) BFC/BFS with the Main Engine Controller redundant back ups.
Mark Kirkman
He would have had to confuse STS-114 with STS-93 as well. We didn't lose any DCUs on 114.
-
#978
by
elmarko
on 14 May, 2008 15:41
-
Danny is referring to 114, not 93
-
#979
by
mkirk
on 14 May, 2008 15:53
-
elmarko - 14/5/2008 10:41 AM
Danny is referring to 114, not 93
Okay in my defense I have severe jet lag as I have just crossed thirteen time zones (Japan to U.S.) - but yes I should have read the post more closely.
At any rate the BFS absolutley was not engaged during Ascent.
Mark Kirkman