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#300
by
Chris Bergin
on 29 Jul, 2009 23:03
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#301
by
ginahoy
on 30 Jul, 2009 17:04
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I have two shuttle-related questions:
1) To what extent if any was the orbiter weight constrained by the 747 ferry requirement when the sts was being designed?
2) In an emergency, could an astronaut make a brief spacewalk in the current ACES, being that it's a full-pressure suit?
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#302
by
Sesquipedalian
on 30 Jul, 2009 17:37
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Has there ever been a shuttle landing at KSC while a shuttle rollout was in progress?
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#303
by
Analyst
on 30 Jul, 2009 18:37
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Well, there have been many shuttle landings a split of a second before the shuttle rolling out, but ... this is not your question.
Analyst
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#304
by
Jim
on 30 Jul, 2009 19:37
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I have two shuttle-related questions:
1) To what extent if any was the orbiter weight constrained by the 747 ferry requirement when the sts was being designed?
2) In an emergency, could an astronaut make a brief spacewalk in the current ACES, being that it's a full-pressure suit?
1. no.
2. no.
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#305
by
butters
on 30 Jul, 2009 23:58
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How does the orbiter's onboard flight simulator work? For example, when they practice entry and landing before deorbit, do they throw switches on the flight deck control panels? How is the simulation environment isolated from the flight environment? Is it just a GPC video game that temporarily takes over the rotational hand controller?
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#306
by
Jim
on 31 Jul, 2009 00:13
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How does the orbiter's onboard flight simulator work? For example, when they practice entry and landing before deorbit, do they throw switches on the flight deck control panels? How is the simulation environment isolated from the flight environment? Is it just a GPC video game that temporarily takes over the rotational hand controller?
separate laptop with separate handcontroller
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#307
by
Danny Dot
on 31 Jul, 2009 00:35
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And some people think we will be putting this stuff in cars at gas stations someday. I think not.
Danny Deger
Well, I wouldn't necessarily say that. I'm one all for a hydrogen society. It will just take a learning and education process like it was for gasoline way back when. We will develop processes and safety guidelines, develop new specialized hardware and safety equipment. I'm sure there will be accidents and we will learn from them. It's just that, here, we work for a government entity that has it's own safety regulations, industry-wide safety regulations, and we are dealing with a much, much larger amount of commodity that most of the public will ever have to at one time.
You are the expert on this stuff, so you give me a ray of hope. Is the goal liquid or compressed gas. I understand there some prototype stations working today.
But, I don't recall there ever being that big of an issue in handling gasoline into cars. Heck, we don't even ground our cars like we do planes. It takes about 5 seconds to teach someone to gas up a car. If there is a big spill (which there are), it doesn't quickly boil into an explosive cloud. Detonating a cloud is really, really bad. Probably a gallon turning into vapor will level a whole gas station when it goes off.
I can't imagine my ex ever gassing up her car with liquid hydrogen
In my opinion, even liquid propane is something that shouldn't be taken lightly.
Danny Deger
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#308
by
jiehrlich
on 31 Jul, 2009 04:38
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Here's a question before it gets busy:
Are there any photos online of the egress process? Since the hatch opens on the left side when the orbiter is on the pad, I presume that it opens downward on the runway. There must be some interesting hardware to accommodate that...
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#309
by
oxford750
on 31 Jul, 2009 05:40
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Is there an article (for the layman like me) that explains in which direction each thruster fires, and which way it would make the shuttle move?
I know what the OMS engines do, but what about the others?
If one OMS engine failed for any reason, would firing just one for a "longer" period be enough or would that induce a yaw as the other one can't compensate?
Thanks
Oxford750
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#310
by
elmarko
on 31 Jul, 2009 08:38
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Is there an article (for the layman like me) that explains in which direction each thruster fires, and which way it would make the shuttle move?
I know what the OMS engines do, but what about the others?
If one OMS engine failed for any reason, would firing just one for a "longer" period be enough or would that induce a yaw as the other one can't compensate?
Thanks
Oxford750
Attaching a diagram from the Shuttle Crew Operations Manual which should explain things.
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#311
by
MKremer
on 31 Jul, 2009 10:07
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Here's a question before it gets busy:
Are there any photos online of the egress process? Since the hatch opens on the left side when the orbiter is on the pad, I presume that it opens downward on the runway. There must be some interesting hardware to accommodate that...
I'm not sure that's ever been documented, even as far back as the Enterprise landing tests (where they exited via a mostly regular airline mobile stairway).
From STS-1-on, the hatch area has been covered and I can't recall ever seeing any pics of the hatch being opened. or of any crew exiting after a mission.
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#312
by
Jim
on 31 Jul, 2009 12:25
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1. If one OMS engine failed for any reason, would firing just one for a "longer" period be enough or
2. would that induce a yaw as the other one can't compensate?
1. yes
2. The nozzle can be gimbaled to avoid yaw. Also there many times where only one engine is needed
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#313
by
Jim
on 31 Jul, 2009 12:32
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Here's a question before it gets busy:
Are there any photos online of the egress process? Since the hatch opens on the left side when the orbiter is on the pad, I presume that it opens downward on the runway. There must be some interesting hardware to accommodate that...
I'm not sure that's ever been documented, even as far back as the Enterprise landing tests (where they exited via a mostly regular airline mobile stairway).
From STS-1-on, the hatch area has been covered and I can't recall ever seeing any pics of the hatch being opened. or of any crew exiting after a mission.
It isn't anything complex. The top platform of the stairway has an compartment for the hatch. The cover of the compartment serves at the platform where the workers and crew walk on.
The hatch, when open, fits inside the compartment and then it is covered by the platform
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#314
by
oxford750
on 31 Jul, 2009 12:42
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Thanks Jim.
Oxford750
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#315
by
Danny Dot
on 31 Jul, 2009 13:37
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Is there an article (for the layman like me) that explains in which direction each thruster fires, and which way it would make the shuttle move?
I know what the OMS engines do, but what about the others?
If one OMS engine failed for any reason, would firing just one for a "longer" period be enough or would that induce a yaw as the other one can't compensate?
Thanks
Oxford750
If one fails the other can very easily take up the job with a longer burn. The system was designed to do this. With a single engine OMS burn the single engine is fired through the center of gravity, which creates no yawing or pitching moments. IIRC, RCS roll jets are used to correct for any roll that might creep in.
For a two engine burn, both engines are put parallel to the body (not through the c.g.). This is OK, but they counter each other and no yaw results. For roll control, one goes up, and one goes down.
If things get really bad, the OMS propellant can be piped to the RCS jets and they can be used. Not as efficient though. For one thing they are NOT perfectly through the c.g. and when they are burned, some pitch jet firing is always needed to take care of pitch control.
They will not give the same delta V for the same propellant load.
I don't remember if the rules require there always be enough prop to do an RCS burn if needed. I think they do. This gets complex fast, because you can do things like get by with a lesser burn and compensate by hitting the atmosphere at 90 degrees of bank instead of the typical wings level. I think this saves about 800 pounds of propellant. I actually put in a cost saving suggestion once to start doing this nominally to increase ascent performance. I was a new instructor. This action, did not make the flight controller happy with me. There was a lot of undue concern that "pre-bank" would increase shuttle heating. The story of this confusion, has to wait for another day. It is fairly long and complex, and I have to watch David Wolf and his team get back home.
Danny Deger
P.S. I think the good SODB is on L2 somewhere. I can't find it. I don't mean the cheesy one on the internet that is basically a bunch of pictures. I mean the one that reads like an owners manual for the shuttle.
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#316
by
elmarko
on 31 Jul, 2009 16:49
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Would love to hear the rest of that story, Danny. So you were advocating the use of prebank as a nominal procedure? What happens then if you underburn?
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#317
by
Danny Dot
on 31 Jul, 2009 17:28
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Would love to hear the rest of that story, Danny. So you were advocating the use of prebank as a nominal procedure? What happens then if you underburn?
I was advocating nominal prebank entry. Response to an underburn was one of the problems. Underburn prebank was not an official reserve for OMS problems, but it was considered a hip pocket reserve. I argued it should be put in the rules if it was used as such.
On the heating confusion, if a prebank is required as the result of an underburn, the orbiter is own a high energy profile. This results in a high temp entry. Because we often did under burn prebank cases in training, the world got to have a one on one association with prebanks and overtemps. This is what I was taught.
Nominal prebanks were not in the card deck, so we didn't see them. They were allowed in the flight rules for OMS propellant failures, but never trained because the case was and is much harder to get in the simulator. It is also pretty much a long sim run, that isn't done much.
I was told the inventor of Entry Guidance, Jon Harpold, would never even think of nominal prebanks. At the time he was head of MOD, so picking up the phone and calling him was not to be taken lightly. I finally did and he basically said, "Not really a problem now. Early in the program, I wanted a wings level entry because it was steeper and more tolerant to any errors in the system. Now that we have flown many times, I don't think coming in with 90 degrees of bank would be a problem. We know enough about all the errors, the shallower entries would be OK. And you are correct a planned perbank entry has the same temperatures"
Shortly after this conversation, I wrote the cost saving suggestion which basically got thrown back into my face. I realize just writing the suggestion, was not good for my career.
Danny Deger
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#318
by
mmeijeri
on 31 Jul, 2009 17:51
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http://www.spacetransportnews.com/ had a link today to an MIT Open Courseware
video course on the Space Shuttle with lots of prominent designers who were involved with the design of the shuttle. Lecture #9 is about the OMS, RCS, APU and hydraulics and it briefly discusses using RCS for the deorbit burn. It's a great course, highly recommended.
There's also a great
document on Shuttle OMS and RCS on
http://www.shuttlepresskit.com/.
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#319
by
elmarko
on 31 Jul, 2009 18:20
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That document you linked is from the SCOM, the full version of which is on L2.
Thanks for the lecture though, looks great!
?
) , but when was STS-134 announced??? I thought the schedule went to STS-133 but the NASA site is showing an additional flight for launch on Sept 16th. Cant believe I'm the 1st to see this but can not see a thread?
?
