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#2380
by
MarsMethanogen
on 16 Nov, 2011 23:01
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Hi all.
this kind I have kind of "silly" question. I find quite curiuos the software for the shuttle was written in a language called HAL/S running on IBM computers. As it's known HAL is the name of the computer on 2001: A Space Odyssey and it's an implict reference to IBM (every letter in HAL is the letter soon after each letter in IBM).
I'd like to know is there is any particular reason for which language for the shuttle software was named HAL.
Thanks very much
Davide
Regarding your "implicit reference to IBM" statement. Quickly off-topic, but both Kubrick and Clarke, before they passed on, said that in creating the HAL acronym, such a relationship never occurred to them, and that it was purely coincidental.
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#2381
by
Jorge
on 17 Nov, 2011 01:30
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Hi all.
this kind I have kind of "silly" question. I find quite curiuos the software for the shuttle was written in a language called HAL/S running on IBM computers. As it's known HAL is the name of the computer on 2001: A Space Odyssey and it's an implict reference to IBM (every letter in HAL is the letter soon after each letter in IBM).
I'd like to know is there is any particular reason for which language for the shuttle software was named HAL.
Thanks very much
Davide
Regarding your "implicit reference to IBM" statement. Quickly off-topic, but both Kubrick and Clarke, before they passed on, said that in creating the HAL acronym, such a relationship never occurred to them, and that it was purely coincidental.
Clarke even joked about it in the 2010 novel.
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#2382
by
alk3997
on 17 Nov, 2011 01:37
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Hi all.
this kind I have kind of "silly" question. I find quite curiuos the software for the shuttle was written in a language called HAL/S running on IBM computers. As it's known HAL is the name of the computer on 2001: A Space Odyssey and it's an implict reference to IBM (every letter in HAL is the letter soon after each letter in IBM).
I'd like to know is there is any particular reason for which language for the shuttle software was named HAL.
Thanks very much
Davide
What AnalogMan wrote is accurate. The language was named in the early 1970s timeframe. The name fit very well in so many ways.
What you have to remember is at the time, the languages were named Cobol and Fortran and Pascal. The big deal with HAL was that it was high order but still allowed for easy bit-manipulation. So, that it started with high-order (H) made sense. That there was still assembly language (AL) is a reference to the bit-manipulations available. I guess is could have been HOAL but HOAL wouldn't have been asked about 40 years later.
The funny thing is that within the program, the reasons for HAL being named HAL was often different depending upon who you asked.
It may have been a case of the acronym coming before the definition, but I think the reasoning for the name has been lost to history.
Andy
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#2383
by
Fequalsma
on 19 Nov, 2011 03:09
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So here are a couple of questions for all you rocketeers out there:
1/ In the recent IMAX movie "Hubble 3D", they show several excellent sequences of the Shuttle launching. However, I noticed that the water bags across the SRB flame holes were not there in one of these shots. I thought these were installed on every launch after STS-1. So what's the story?
2/ The Shuttle's SRBs/SRMs were modified shortly after STS-1 (and before STS-51L) to reduce weight and improve performance. What mods were made? Does anyone have references?
v/r,
F=ma
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#2384
by
alk3997
on 19 Nov, 2011 05:13
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So here are a couple of questions for all you rocketeers out there:
2/ The Shuttle's SRBs/SRMs were shortly after STS-1 (and before STS-51L) to reduce weight and improve performance. What mods were made? Does anyone have references?
v/r,
F=ma
Did you mean the External Tank or the SRBs for weight reduction? The standard ET was indeed reduced to the lightweight tank (and then the superlightweight tank). Each pound of Tank reduction was roughly equal to a pound more that could be carried into orbit.
The SRB equation is not quite as good since the SRBs only made the first 2 minutes and 4 seconds of the journey. So a pound of SRB weight reduction resulted in a fraction of a pound into orbit.
I know some instrumentation was removed but I'd have to defer to the KSC folks for any real SRB weight reductions after STS-1. Considering the SRMs were reusable, that would mean the pre-existing cases would have to be modified for any weight reduction (or the old cases tossed) or the forward cone or nozzle assembly/aft weights were reduced.
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#2385
by
Fequalsma
on 19 Nov, 2011 13:33
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I did mean the early, pre-Challenger SRB mods. I seem to recall reading somewhere that these 2nd-gen shell walls were ~0.45 inches thick, vs the original 0.50 inches.
From
http://choo.fis.utoronto.ca/FIS/Courses/LIS2102/DM.case.html:
"During 1983, the SRBs were modified to use thinner walls, narrower nozzles, and more powerful fuel..."
I do realize that the "gear ratio" for the SRBs is ~10:1, where a 10 lb reduction in the SRBs => 1 lb to LEO. Obviously, the Orbiter and ET have better gear ratios (~1:1), but you takes your performance gains wherever you can, I guess...
Of course, if you have any documentation on the original Standard-Weight Tank, I'd also like to see that! Is there a Systems Definition Handbook for the SWT out there, somewhere?
Cheers,
F=ma
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#2386
by
AnalogMan
on 19 Nov, 2011 14:27
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I did mean the early, pre-Challenger SRB mods. I seem to recall reading somewhere that these 2nd-gen shell walls were ~0.45 inches thick, vs the original 0.50 inches.
From http://choo.fis.utoronto.ca/FIS/Courses/LIS2102/DM.case.html:
During 1983, the SRBs were modified to use thinner walls, narrower nozzles, and more powerful fuel..."
There is this note from the ATK SRB Bible regarding wall thicknesses (on L2)
Cylinders are classified according to the membrane thickness requirements:
• Lightweight cylinder thickness are 0.450 to 0.499 in.
• Standard weight cylinder thickness are 0.477 to 0.526 in.
• Early SRM configuration used standard weight cylinders only
• HPM design increased pressure (950 to 1,000 psia) and reduced thickness
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#2387
by
jeff122670
on 20 Nov, 2011 19:01
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During STS-135, GLS and OTC were both female...however, in years past, they voices always sounded the same to me, so I thought it was one person....However, for 135, it was obviously two different females. Anyone know who CGLS and the OTC were for STS-135. I am assuming it was Roberta Wyrick as OTC.
Thanks!
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#2388
by
psloss
on 20 Nov, 2011 19:51
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During STS-135, GLS and OTC were both female...however, in years past, they voices always sounded the same to me, so I thought it was one person....However, for 135, it was obviously two different females. Anyone know who CGLS and the OTC were for STS-135. I am assuming it was Roberta Wyrick as OTC.
Different positions, never one person. Ms. Wyrick was OTC and Janine Pape was GLS; both were noted in the launch day thread.
(And
elsewhere.)
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#2389
by
sivodave
on 20 Nov, 2011 22:12
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Hi all.
Question on the avionics system. I understand the way in which the redundant set works, however I don't understand if in case of need, both ascent and reentry could be flown with just one GPC in GNC mode running PASS.
Obviously with just on GPC you loose all the FO/FS condition, but would it be theoretically possible flying with just one GPCs? My guess is no, is not possible. Since you should have at least two GPCs for commanding two different strings, otherwise maneuvering with the RCS wouldn't be possible (for example).
which are your thoughts?
thanks
Davide
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#2390
by
Jorge
on 20 Nov, 2011 22:16
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Hi all.
Question on the avionics system. I understand the way in which the redundant set works, however I don't understand if in case of need, both ascent and reentry could be flown with just one GPC in GNC mode running PASS.
Obviously with just on GPC you loose all the FO/FS condition, but would it be theoretically possible flying with just one GPCs? My guess is no, is not possible. Since you should have at least two GPCs for commanding two different strings, otherwise maneuvering with the RCS wouldn't be possible (for example).
which are your thoughts?
thanks
Davide
It is possible for one PASS GPC to control all four strings. Not particularly wise, but it is possible.
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#2391
by
Colds7ream
on 21 Nov, 2011 14:34
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Hi everyone, quick question regarding SSMEs - I've read that they are referred to from an engineering standpoint mostly as RS-25 engines, but that RS-24 is an alternate designation - is this correct, and, if so, what is the difference between the two models, please?
In addition, I'm aware that the last half or so of the programme used Block II engines, but were the preceding models all Block I standard or were there other variants thereof?
Finally, I've seen the SLS engines being referred to as RS-25D/E - does this mean that they are RS-25D and RS-25E and there is a distinction between the two, or simply that the SLS engines are actually designated as D/E variants?
Many thanks in advance!
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#2392
by
wolfpack
on 21 Nov, 2011 14:44
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Hi everyone, quick question regarding SSMEs - I've read that they are referred to from an engineering standpoint mostly as RS-25 engines, but that RS-24 is an alternate designation - is this correct, and, if so, what is the difference between the two models, please?
In addition, I'm aware that the last half or so of the programme used Block II engines, but were the preceding models all Block I standard or were there other variants thereof?
Finally, I've seen the SLS engines being referred to as RS-25D/E - does this mean that they are RS-25D and RS-25E and there is a distinction between the two, or simply that the SLS engines are actually designated as D/E variants?
Many thanks in advance!
I think the RS-25E is the expendable version. Basically less rugged turbopump design as no need for reuse. RS-25D is what they have sitting in a building now at KSC since they've gutted the Orbiter's MPS for SLS. There are something like 15 of them IIRC.
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#2393
by
alk3997
on 21 Nov, 2011 15:55
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Here's a good reference for the other half of your question...
http://history.msfc.nasa.gov/shuttle/documents/space_shuttle_main_engine_30_years_innovation.pdfBasically, Original --> Phase II --> Block I --> Block IIA --> Block II
My memory is that when possible we flew a single SSME of the new type with two of the earlier type and basically phased in each upgrade in case there was a surprise. One engine out was survivable (assuming it didn't take another engine with it), two engines out was possibly survivable. So, there was a big advantage to trying a change out with a single engine first.
Andy
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#2394
by
alk3997
on 21 Nov, 2011 16:05
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Hi all.
Question on the avionics system. I understand the way in which the redundant set works, however I don't understand if in case of need, both ascent and reentry could be flown with just one GPC in GNC mode running PASS.
Obviously with just on GPC you loose all the FO/FS condition, but would it be theoretically possible flying with just one GPCs? My guess is no, is not possible. Since you should have at least two GPCs for commanding two different strings, otherwise maneuvering with the RCS wouldn't be possible (for example).
which are your thoughts?
thanks
Davide
Not wise but certainly do-able. When we were testing application software (such as ascent guidance), the majority of all the FEID testing (where the flight software was tested and verified) was done in single string (which is what flying with one GPC is called). From an applicaion program standpoint, the system didn't know the difference between one GPC and four GPCs flying the system. All strings are assigned to the single GPC with the NBAT, so all databus strings are still being commanded - just by one GPC. All of the GPCs listened to all of the busses, so that didn't change no matter how many GPCs were in the set.
Now that's great for on the ground application testing, but I wouldn't bet my life on a single GPC working through ascent and entry over 30 years -- even the AP-101S. The groundrules were basically to fly dynamic flight with four GPCs and then if you lost one you were OK. If you had two GPCs left and then another failed, you probably were on the BFS at that point because you might not know which of the two that failed was the good one (both would likely indicate the other was bad).
Bottom line - a very flexible O/S and redunancy management system did allow for single string ops that were pretty much the same as any other combo of GPCs, as long as there were no failures that would knock-out that remaining GPC.
Andy
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#2395
by
Colds7ream
on 21 Nov, 2011 16:28
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Brilliant, thanks very much! Two things I'm still unsure about - what is an RS-24, and what differentiates an RS-25D from a Block II SSME? Cheers!
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#2396
by
alk3997
on 21 Nov, 2011 16:50
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Here's the best reference I could find on what the engine designations mean. But basically an RS-25D = SSME (Block II or otherwise)
http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/asd/2011/10/24/06.xmlThe RS-24 designation is a bit confusing to me. We just called them SSMEs in my part of the program and in the official documentation (along with Block II or whatever mod level we were at). So, the terms RS-24 and RS-25 were not used. We had SSMEs.
I can find no reasonably official reference to an SSME being called RS-24. Rocketdyne refers to the SSME as an RS-25D.
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#2397
by
Colds7ream
on 21 Nov, 2011 17:08
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Cheers, much appreciated! :-)
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#2398
by
Colds7ream
on 21 Nov, 2011 17:19
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On a not-totally-unrelated note, I'm slightly confused by this chart from P&W:
http://collectspace.com/review/sts133_ssmechart-lg.jpg - weirdly, engines 2012, 2018 and 2109 were all used on '25', then were flown again on 27 and 32? Unless I'm missing something, isn't that impossible? :-S
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#2399
by
alk3997
on 21 Nov, 2011 17:25
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Remember KSC had a different numbering scheme since they didn't go by the ##L designation. So KSC used just numbers for the flights up until 51L. So, the 25 you see isn't for 51L.
After return to flight, the R was put after the number on the KSC numbering to designate a flight number that had already been used prior to 51L. After that KSC and the rest of the program all used the same numbering system for flights.