-
#2300
by
HelixSpiral
on 15 Sep, 2011 17:58
-
Not sure how about trajectory error, but IIRC there was a small performance penalty with the rolling heads up vs. staying heads down.
-
#2301
by
sivodave
on 16 Sep, 2011 14:23
-
now the question of the day: for the ascent the pilots can see the information regarding the progress of the ascent on three different displays, which are ASCENT TRJ 1 (used up to SRB sep), ASCENT TRJ 2 (used up to ET sep) and ASCENT TRJ (it displays the whole ascent). This is at least what I've understood from what I've been reading lately. My question is: when the ASCENT TRJ is used? Also are the ASCENT TRJ 1 and 2 generated by the PASS or by the BFS?
Hi all.
no answer about this? I really need to understand this thing.
thanks very much for your help
Davide
-
#2302
by
HelixSpiral
on 17 Sep, 2011 17:16
-
Originally, the PASS used a single display for both first stage and second stage called ASCENT TRAJ. AIUI, this was intended to help fly an RTLS, and its usefulness after Negative Return was limited. BFS used one display for first stage and a different display for second stage (ASCENT TRAJ 1 and 2).
For the OI-32 (I believe) software release, the PASS displays were changed to more closely resemble the BFS displays.
-
#2303
by
sivodave
on 18 Sep, 2011 20:10
-
[quoteHelixSpiral]Originally, the PASS used a single display for both first stage and second stage called ASCENT TRAJ. AIUI, this was intended to help fly an RTLS, and its usefulness after Negative Return was limited. BFS used one display for first stage and a different display for second stage (ASCENT TRAJ 1 and 2).
For the OI-32 (I believe) software release, the PASS displays were changed to more closely resemble the BFS displays. [/quote]
Interesting to know, but basically now which displayes are displayed during the different ascent phases?
And just to know, what OI-32 stands for?
Thanks
-
#2304
by
elmarko
on 19 Sep, 2011 12:22
-
Operational Increment 32, essentially version 32 of the flight software (I think!)
-
#2305
by
sivodave
on 20 Sep, 2011 06:43
-
why is it important for the pilots, during ascent to view the horizon in front of them? this is one of the reason for which the roll program is executed.
Thanks
Davide
-
#2306
by
alk3997
on 20 Sep, 2011 06:54
-
I've been away for a little bit, so let me catch-up and give you a bit of detail.
First on your question about the ascent traj displays, there is a good account of that in Part 4 of the Shuttle Q&A (MKirk I believe appended). One should always check the archives before asking new questions.
Yes for many years BFS had a much better first stage ascent traj display and a better second stage ascent traj display than PASS. The 6X Traj upgrade for OI-32, did indeed update the PASS displays into a much more usable format. 6X stands for the XXXXXX in front of the Traj on the display title. These can be changed to different abort modes such as RTLS, as well. So your question about whether these are 1 or 2 is actually irrelevent - they were three or one depending upon how you look at a different display format. The transitions were done automatically, so from a pilot stand-point I think one format with different options may be a good way to look at it. From a requirements standpoint, each format had its own requirements. So, you can choose your own answer.
Keep in mind that the crew had a good number of displays to choose from during ascent. Of course my favorite for the last two OIs being the Bearing Display (see Shuttle flight software paper topic in the historic spaceflight forum -
http://forum.nasaspaceflight.com/index.php?topic=26630.0) which provided two maps spanning the U.S. east coast to Europe as well as orbiter velocity and position indications overlayed on the map. There were also a number of systems displays.
http://www.unitedspacealliancenewsroom.com/usa-in-the-news/news-releases/sts-126-launches-with-new-software-that-enhances-astronaut-safety/OI-32 is indeed Operational Increment but it wasn't the 32nd version of the flight software. We skipped numbers (some were "test" OIs) and also occasionally used a letter after the OI number (OI-26B for instance). However the final OI was OI-34.
And, seeing the horizon was not the reason for the roll program. The roll program was there because the launch pad could only face one way (tail to the south). To get to the proper azimuth at launch then required a roll. Roll to heads down was primarily for load relief, after initial program studies showed less pressure on the wings heads down than heads up. After a few flights, I'm told that using actual flight data made the different irrelevent but RTLS was easier to setup heads-down (work it out by "flying" RTLS with your hands).
So, why did you "really need" to know this in such a hurry? I'm curious...
Andy
-
#2307
by
Jorge
on 20 Sep, 2011 07:54
-
OI-32 is indeed Operational Increment but it wasn't the 32nd version of the flight software. We skipped numbers (some were "test" OIs) and also occasionally used a letter after the OI number (OI-26B for instance). However the final OI was OI-34.
There was also a wholesale change in the numbering philosophy with, I think, OI-8D giving way directly to OI-20.
-
#2308
by
alk3997
on 20 Sep, 2011 13:45
-
OI-32 is indeed Operational Increment but it wasn't the 32nd version of the flight software. We skipped numbers (some were "test" OIs) and also occasionally used a letter after the OI number (OI-26B for instance). However the final OI was OI-34.
There was also a wholesale change in the numbering philosophy with, I think, OI-8D giving way directly to OI-20.
That's right. When the then-new AP-101S computers started flying, we did some numbering tricks. The flight sequence was OI-8D (AP-101B) to OI-8F (AP-101S using OI-8D application software but designed for the new GPC) and then OI-20 (starting to take advantage of the AP-101S). So, the sequence went OI-8D, OI-8F and OI-20.
The OI-12 line was for trying out things with the new computers as I recall. There was also the Centaur OI (7C), the CAU OIs and a few other test systems along the way.
Andy
-
#2309
by
sivodave
on 20 Sep, 2011 18:09
-
One of the parameters computed by PEG during the second-stage guidance, is the reference thrust vector, which is defined as a unit vector in the direction of the velocity to be gained Vgo, indicating the constant thrust direction that would achieve the desired velocity.
Am I understing right that this is a vector fixed during all the ascent representing the thrust vector velocity at MECO? Also if I've understood well, aim of PEG is to rotate the real thrust vector in order to have its direction parallel to the reference thrust vector. Am I correct?
thanks very much
Davide
-
#2310
by
alk3997
on 23 Sep, 2011 01:00
-
-
#2311
by
joncz
on 23 Sep, 2011 14:08
-
I suspect the crew compliment would have a lot to do with sea-time.
Andy
<Captain> Crew, you're a very nice crew. It's a pleasure to work with you!
<Crew> Captain - thanks for the compliment! We'll stay out another month with you for those nice words!
-
#2312
by
DMeader
on 23 Sep, 2011 14:18
-
The food probably has a lot to do with it as well.
-
#2313
by
Ronsmytheiii
on 23 Sep, 2011 19:27
-
Does anyone know what happened to the prototype SSME, the ISTB?
-
#2314
by
Wepush
on 23 Sep, 2011 21:04
-
The ISTB tested for a long time, was rebuilt and tested some more. The main parts were destroyed in a lox fire in ‘78. The nozzle tested on another engine, but was eventually destroyed in a different incident in ‘85. (You can read about both of these incidents in the Bob Biggs book on the SSME - see tests 901-120 (was actually 902-120) on engine 0101 and test 750-259 on Engine 2308.)
-
#2315
by
alk3997
on 23 Sep, 2011 21:05
-
I suspect the crew compliment would have a lot to do with sea-time.
Andy
<Captain> Crew, you're a very nice crew. It's a pleasure to work with you!
<Crew> Captain - thanks for the compliment! We'll stay out another month with you for those nice words!
Fair enough - I should have reminded myself about the complement and then you could have given me a compliment.
Andy
-
#2316
by
Fequalsma
on 24 Sep, 2011 01:19
-
Do you have a citation or link for this book, Wepush?
the Bob Biggs book on the SSME
-
#2317
by
GoForTLI
on 24 Sep, 2011 01:24
-
-
#2318
by
Fequalsma
on 24 Sep, 2011 01:31
-
Thanks very much!
F=ma
Do you have a citation or link for this book, Wepush?
the Bob Biggs book on the SSME
Space Shuttle Main Engine
The First Ten Years
by Robert E. Biggs
http://www.enginehistory.org/ssme.shtml
-
#2319
by
Wepush
on 24 Sep, 2011 01:48
-
Even better:
Space Shuttle Main Engine: The First Twenty Years and Beyond. By Robert E. Biggs. San Diego, Calif.: American Astronautical Society, 2008 [AAS History Series, volume 29].
