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#3080
by
Jim
on 26 Feb, 2014 16:58
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Foam was a big part of it.
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#3081
by
JayP
on 28 Feb, 2014 16:32
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I'm working on a project dealing with the layout of mechanical systems and I'm using the shuttle airlock hatch 5 bar hinge design as an example. Does anyone know what the X and Y dimensions in the attached sketch would be or know of a document that would lay this out. Thee rest of it can be determined once we know where the hatch ends up when it is open relative to it's closed position. it doesn't matter which of the 3 hatches we go by, the linkage design is functionally the same in all cases. Thanks,
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#3082
by
DaveS
on 02 Apr, 2014 01:46
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Does anyone know the weights for the Orbiter Docking System and the External Airlock with the truss assembly? I'm not talking about both added together but separately.
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#3083
by
DaveS
on 04 Apr, 2014 17:29
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I'm curious about the dimensions (X and Y) of the payload umbilical access panel on the orbiter midbody. It's the one with the red lines in the attached photo.
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#3084
by
Hoonte
on 13 May, 2014 07:43
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What was the first shuttle flight that had full orbital communicatons (so no LOS)?
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#3085
by
Jim
on 13 May, 2014 09:44
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What was the first shuttle flight that had full orbital communicatons (so no LOS)?
There was always ZOE and antenna blockage. STS-26 and STS-29 delivered the 2nd and 3rd TDRS. So somewhere in between LOS was reduced to 85%
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#3086
by
psloss
on 13 May, 2014 11:53
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The Space Shuttle Missions Summary reference says STS-27 was the first flight with TDRS-East and West. (Also first flight with "no comm blackout" during re-entry.)
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#3087
by
sivodave
on 13 May, 2014 16:25
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Hello all.
Quick question about the IUS and PAM-D upper stages. After having deployed the upper stage, the Shuttle had to orient itself, in such a way to use the belly as a shield from the upper stage rocket exhausts. Obviously by the time the upper stage fired the orbiter would have been at a certain distance, but what if some damage occurred to the belly? how could they know if it had been damage in the first place? with no OBSS or procedure for checking out the belly with the RMS (as capability demonstrate by STS-8), how could they have know if the belly had been compromise? I've to say this type of procedure for satellite deployment has always made me raise an eyebrow.
Thanks very much
Davide
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#3088
by
psloss
on 13 May, 2014 16:36
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Quick question about the IUS and PAM-D upper stages. After having deployed the upper stage, the Shuttle had to orient itself, in such a way to use the belly as a shield from the upper stage rocket exhausts. Obviously by the time the upper stage fired the orbiter would have been at a certain distance, but what if some damage occurred to the belly?
There was a sequence of post-deploy separation burns with a pretty large one (relatively speaking) at the end, so by the time of upper stage ignition it was fairly great distance.
(The STS-44 mission report has the OMS sep burn as a two-engine burn with a delta-V of ~30 fps.)
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#3089
by
sivodave
on 13 May, 2014 16:53
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There was a sequence of post-deploy separation burns with a pretty large one (relatively speaking) at the end, so by the time of upper stage ignition it was fairly great distance.
that's true, but why then taking anyway the precaution of using the belly as a shield? it was fairly distance, it wouldn't have mattered the shuttle attitude at the time of upper stage ignition.
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#3090
by
psloss
on 13 May, 2014 17:06
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There was a sequence of post-deploy separation burns with a pretty large one (relatively speaking) at the end, so by the time of upper stage ignition it was fairly great distance.
that's true, but why then taking anyway the precaution of using the belly as a shield? it was fairly distance, it wouldn't have mattered the shuttle attitude at the time of upper stage ignition.
Press kits say to protect the orbiter windows:
http://science.ksc.nasa.gov/shuttle/missions/sts-44/sts-44-press-kit.txtAt approximately 45 minutes after ejection from the orbiter,
the pyrotechnic inhibits for the first solid rocket motor are
removed. The belly of the orbiter has been oriented towards the
IUS/DSP combination to protect the orbiter windows from the IUS's
plume. The IUS recomputes the first ignition time and maneuvers
necessary to attain the proper attitude for the first thrusting
period.
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#3091
by
JAFO
on 19 May, 2014 05:43
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I know the Apollo astronauts trained and could theoriticly fly the Saturn V to orbit, but I also remember reading the Shuttle could not because of the complexity of the boost phase. Another gent is telling me this was only true under stage 1 boost (SRB powered) but after they were jettisoned the Shuttle could be manually flown to orbit.
Thought? TIA.
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#3092
by
Jim
on 19 May, 2014 13:05
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I know the Apollo astronauts trained and could theoriticly fly the Saturn V to orbit, but I also remember reading the Shuttle could not because of the complexity of the boost phase. Another gent is telling me this was only true under stage 1 boost (SRB powered) but after they were jettisoned the Shuttle could be manually flown to orbit.
Thought? TIA.
They would follow the same guidance that the autopilot would be using. The point is that if the guidance failed, there is no way the crew could fly to orbit.
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#3093
by
Specifically-Impulsive
on 19 May, 2014 13:51
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Manual control (CSS mode) was available during the entire ascent phase. It was extremely difficult during first stage due to the control authority available from the SRB TVC.
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#3094
by
alk3997
on 19 May, 2014 14:08
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I know the Apollo astronauts trained and could theoriticly fly the Saturn V to orbit, but I also remember reading the Shuttle could not because of the complexity of the boost phase. Another gent is telling me this was only true under stage 1 boost (SRB powered) but after they were jettisoned the Shuttle could be manually flown to orbit.
Thought? TIA.
Could you fly the Shuttle stack manually into orbit? Technically yes, but you probably would not have survived first stage. Control Stick Steering was available and the CDR/PLT and the ground always made sure they didn't accidentally switch to CSS while the crew was getting into their seats.
But, having tried this in the SMS, first stage ended up with manual control flying all over the sky. Because the large amount of SRB thrust and the way the SRB nozzles moved, a little stick input would produce a large amount of vehicle position change. In the simulator, that worked. In real life, the wings would have been torn off by atmospheric pressure.
The other thing to remember, like Jim said, is that the only way to get into orbit would have been to follow guidance. Well, if guidance is working why would you take the risk of flying the vehicle manually during powered flight? So, while it's "cool" to think that someone could have flown to orbit manually, there wasn't really a reason since you would have had to fly manually.
By the way, before we automated some of the two-engine out and three-engine out modes, the crew was taught to fly the last parts of second stage manually. They did this because certain attitude or positional targets had to be met at certain times and the software had not yet been designed for those very-off-nominal situations.
So, second stage manual capabilities were trained but not for reaching orbit. Also I must remind you that even so-called manual inputs went through the flight computers since this was a fly-by-wire vehicle.
Andy
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#3095
by
wolfpack
on 19 May, 2014 16:55
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I believe flight rules prohibited manual control for the first 90 seconds of powered ascent.
The reality is it was very unlikely you could control the vehicle at any point with the SRB's attached and not exceed load limits. Both fixed and motion simulators assumed the stack was a rigid body and required the sim operator to inform the crew that they got crushed like a beer can.
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#3096
by
Specifically-Impulsive
on 19 May, 2014 19:16
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How would the sim operator have known that?
I have some knowledge of the SMS models, BTW.
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#3097
by
wolfpack
on 19 May, 2014 19:29
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How would the sim operator have known that?
I have some knowledge of the SMS models, BTW.
Maybe not the operator in real-time, but post-process the data and figure out if load limits were exceeded. In other words, you couldn't "snap the wings off" in the simulator. Somebody had to go do some math after the fact and tell you whether you survived or not.
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#3098
by
mkirk
on 19 May, 2014 21:31
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My 2 cents regarding a couple points not yet covered in the discussion so far of CSS (control stick steering or manual control) prior to 90 seconds into the ascent/launch.
I was always taught – and this is what I always repeated to students (usually VIP guests since the CB types understood this already) – the real concern with CSS during this timeframe was “load relief”.
Remember 1st stage guidance was “open loop”. All the shuttle stack is trying to do during this timeframe is maintain a canned attitude versus velocity profile. However, there were combinations of inputs to guidance from the Orbiter and SRB rate gyro assemblies (RGAs), and orbiter accelerometer assemblies (AAs) that allowed the vehicle to manage loads on the stack and wings. The exact combination of inputs was body axis dependent. For example we used the roll rates from the orbiter RGAs instead of the SRB RGAs because of their relative distances from the center of gravity (CG).
In perhaps an oversimplified explanation, the shuttle managed “load relief” by;
- steering the stack into the wind
- adjusting the SSME (space shuttle main engine) throttle level (during the bucket) based on “hot” or “cold” burning SRBs (This was done based on a “snapshot” of vehicle performance at about T+20 seconds. If you got to the expected velocity cue for the 20 second point early, then you had hot boosters, if you got to that velocity point a little later than 20 seconds, then you had cold boosters)
- wing loading was managed by deflecting - usually differentially - the orbiter elevens (and there was certainly no way to do that with the control stick in the cockpit)
From the perspective of the cockpit you did not have the necessary cues and feedback to make these kinds of adjustments. Just keeping the ADI (attitude indicator) needles centered would not do the trick. As an example, a perfectly nominal ascent could occur with deflected needles. This is because the ADI needles are displaying attitude error, but guidance during the load relief phase would preferentially manage loads over attitude. So it was perfectly normal on some days to see the orbiter steer away from the planned/canned 1st stage attitude in an effort to manage vehicle loads. On launch day we briefed the crew on the expected atmospheric conditions and winds aloft so that they would not be surprised by these attitude excursions.
Training to fly manual 1st stage ascents was pretty straight forward. We only trained the crews to take CSS after 90 seconds (which was past the load relief region). After 90 seconds the technique was to fly the pitch attitude (theta) supplied to them on the ADI CUE card (remember this was a good approximation since 1st stage guidance was open loop and was based on a canned profile of attitude verses velocity). The crew would also yaw to keep the HSI (horizontal situation indicator) bearing pointer under the lubber line and then roll out the resulting bank caused by the yaw maneuver – this Beta (or sideslip) management technique was done in an effort to keep from violating thermal constraints.
Mark Kirkman
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#3099
by
spacecane
on 20 May, 2014 11:40
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How was SRB ignition synchronized? I'm interested in the design of the control system that guaranteed the ignition signals would arrive simultaneously to each SRB. Did it require that the communication wiring from the orbiter to the SRBs be exactly the same length to each one?
What was the maximum acceptable difference in ignition time between the two SRBs?
