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#100
by
nacnud
on 11 Nov, 2005 15:25
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What about removing gap fillers on a HSM? /pokeing dead horse
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#101
by
Flightstar
on 11 Nov, 2005 16:16
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nacnud - 11/11/2005 10:25 AM
What about removing gap fillers on a HSM? /pokeing dead horse
Expect the problem with gap fillers to be no more following the new bonding solution that is being implemented as we speak in the OPFs
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#102
by
MKremer
on 11 Nov, 2005 16:25
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nacnud - 11/11/2005 10:25 AM
What about removing gap fillers on a HSM? /pokeing dead horse
Too risky to maneuver that close to the tiles, especially without a stable platform to use as an 'anchor' for pulling, pushing, or cutting forces.
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#103
by
FransonUK
on 12 Nov, 2005 16:02
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What exactly do they do on a HSM?
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#104
by
Terry Rocket
on 16 Nov, 2005 11:13
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FransonUK - 12/11/2005 11:02 AM
What exactly do they do on a HSM?
I'll field this one
They grab hold of the telescope with the Shuttle robotic arm and hold it in place in the cargo bay. They they replace the batteries and anything else that needs doing on it. Pretty simple, but they have to be careful.
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#105
by
nethegauner
on 16 Nov, 2005 11:19
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Terry Rocket - 16/11/2005 1:13 PM
FransonUK - 12/11/2005 11:02 AM
What exactly do they do on a HSM?
I'll field this one
They grab hold of the telescope with the Shuttle robotic arm and hold it in place in the cargo bay. They they replace the batteries and anything else that needs doing on it. Pretty simple, but they have to be careful.
But before they service the telescope, it is attatched to the FSS cradle in the aft payload bay. The RMS is then used to move ORUs and astronauts around.
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#106
by
Mark Max Q
on 17 Nov, 2005 13:12
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I've always been interested in how the Orbiter stays on the side of the ET during launch. What are the attachments made of to keep the Orbiter from falling off. Seperation seems so simply.
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#107
by
MKremer
on 17 Nov, 2005 15:41
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Mark Max Q - 17/11/2005 8:12 AM
I've always been interested in how the Orbiter stays on the side of the ET during launch. What are the attachments made of to keep the Orbiter from falling off. Seperation seems so simply.
Basically, it's held on by 3 very strong bolts.
If you start reading here:
Orbiter/External Tank Separation System you'll get detailed info about the ET attachments and umbilicals, and how separation occurs. It looks a whole lot simpler than it really is.
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#108
by
GirlygirlShuttlefan
on 17 Nov, 2005 16:34
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MKremer - 17/11/2005 10:41 AM
Mark Max Q - 17/11/2005 8:12 AM
I've always been interested in how the Orbiter stays on the side of the ET during launch. What are the attachments made of to keep the Orbiter from falling off. Seperation seems so simply.
Basically, it's held on by 3 very strong bolts.
If you start reading here: Orbiter/External Tank Separation System you'll get detailed info about the ET attachments and umbilicals, and how separation occurs. It looks a whole lot simpler than it really is.
Pretty baffling, but if I get stuck I'll ask what some of those things mean. NASA pages don't tend to space things out very well
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#109
by
Avron
on 18 Nov, 2005 03:04
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GirlygirlShuttlefan - 17/11/2005 12:34 PM
Basically, it's held on by 3 very strong bolts.
...
Pretty baffling, but if I get stuck I'll ask what some of those things mean. NASA pages don't tend to space things out very well
short summary:
"The forward structural attachment consists of a shear bolt unit mounted in a spherical bearing. The bolt separates at a break area when two pressure cartridges are initiated. The pressure from one or both cartridges drives one of a pair of pistons to shear the bolt, "etc...
The aft structural attachment consists of two special bolts and pyrotechnically actuated frangible nuts that attach the external tank strut hemisphere to the orbiter's left- and right-side cavities. At separation the frangible nuts are split by a booster cartridge initiated by a detonator cartridge. "
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#110
by
kraisee
on 18 Nov, 2005 03:30
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MKremer - 17/11/2005 11:41 AM
Basically, it's held on by 3 very strong bolts.
The bolts look something like this:
![]("<a)
http://68.205.251.208/Public/ShuttleBolt.jpg">
If I recall correctly that particular one is a nose attachment bolt for the Orbiter, but don't quote me
The red caps on either end are the bolt-head, just next to these, at both ends, go a ring of shaped charges designed to cut through the main core of the bolt. At separation (for SRB's too) the shaped charges are detonated, and the bolt is cut at the head. The bolt-head itself is then flung off and is caught in a box designed to trap it and ensure it does no damage (these "Bolt Catchers" you may recall hearing about during the Columbia Accident Investigation).
Anyhow, each of the separation bolts has a completely independant backup system at the other end of the bolt including detonator, charge and complete wiring harness to ensure the bolt can be severed at that end instead about 1/10th of a second later.
And just to help you collect useless factoids - you might be interested to note that Endeavour on STS-108 had a major problem with the primary charges failing completely for SRB separation. None of the primary SRB separation bolts blew at all - potentially a very dangerous situation. Luckily though, the backup system took over and blew all the bolts successfully and the launch continued safely. The problem was later traced to faulty wiring.
Ross.
PS - Avron may be right about the explosive charges pushing a piston which slices through the bolt instead. I'm not 100% certain which technique is used.
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#111
by
Chris Bergin
on 18 Nov, 2005 09:34
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Excellent as always, Ross. Never seen such a picture of the bolt before.
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#112
by
nethegauner
on 18 Nov, 2005 09:44
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kraisee - 18/11/2005 5:30 AM
MKremer - 17/11/2005 11:41 AM
Basically, it's held on by 3 very strong bolts.
The bolts look something like this: [...]
Hey, I know where You took
that shot. In the shuttle pavillion at the KSC visitor center, right? I was there too a while ago and had the opportunity to grab this thing and actually lift it. Boy, that was heavy! Amazing, truly amazing ...
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#113
by
Firestarter
on 18 Nov, 2005 22:52
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Shuttle Foam Debris:
If this is such a dangerous thing, why isn't there more concern about the SRB Sep when the separation literally blows a load of foam away with the explosion?
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#114
by
DaveS
on 18 Nov, 2005 23:10
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Firestarter - 19/11/2005 12:52 AM
Shuttle Foam Debris:
If this is such a dangerous thing, why isn't there more concern about the SRB Sep when the separation literally blows a load of foam away with the explosion?
Actually, the Booster Seperation Motors(BSMs) only scorch the ET, I don't believe that they're powerfull enough to cause substantial foam loss. Take a look on this photo of ET-121, following its ride into space during STS-114:
http://spaceflight.nasa.gov/gallery/images/shuttle/sts-114/hires/s114e5002.jpgYou can clearly see the scorching from the BSMs on the intertank and lower part of the LOX tank, but no substantial foam loss.
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#115
by
MKremer
on 19 Nov, 2005 00:46
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Firestarter - 18/11/2005 5:52 PM
Shuttle Foam Debris:
If this is such a dangerous thing, why isn't there more concern about the SRB Sep when the separation literally blows a load of foam away with the explosion?
The booster separation motors' exhaust pressure is pretty insignificant compared to the aerodynamic pressures and forces on the foam during max-Q and trans-sonic acceleration during ascent. Any weak foam areas would have already been ripped off by the time the SRBs separated.
The visible scorching on the ET is mainly due to the heat and exhaust residue of the BSMs.
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#116
by
kraisee
on 19 Nov, 2005 18:39
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DaveS - 18/11/2005 7:10 PM
Firestarter - 19/11/2005 12:52 AM
Shuttle Foam Debris:
If this is such a dangerous thing, why isn't there more concern about the SRB Sep when the separation literally blows a load of foam away with the explosion?
Actually, the Booster Seperation Motors(BSMs) only scorch the ET, I don't believe that they're powerfull enough to cause substantial foam loss. Take a look on this photo of ET-121, following its ride into space during STS-114: http://spaceflight.nasa.gov/gallery/images/shuttle/sts-114/hires/s114e5002.jpg
You can clearly see the scorching from the BSMs on the intertank and lower part of the LOX tank, but no substantial foam loss.
Actually, a number of engineers I have spoken with believe that the SRB separation motors were the "straw that broke the camels back" for the big foam chunk that came off the PAL Ramp on STS-114.
That foam did survive Max-Q and made it all the way into very very thin atmosphere indeed. It is believed that the foam was loosened on the way up, but stayed attached. It is believed that the blast from the SRB sep motors was enough to finally jar the last bit loose completely and that's why it fell away only seconds after the separation event.
Ross.
PS - Yes nethegauner, that's exactly where that pic came from. They do a cool little presentation in there.
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#117
by
MKremer
on 19 Nov, 2005 19:39
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kraisee - 19/11/2005 1:39 PM
It is believed that the foam was loosened on the way up, but stayed attached. It is believed that the blast from the SRB sep motors was enough to finally jar the last bit loose completely and that's why it fell away only seconds after the separation event.
So they seem pretty sure it was from the motor exhaust pressure itself, and not something like sharp vibration transients from the separation pyros?
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#118
by
Shuttle Scapegoat
on 20 Nov, 2005 16:33
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On some of the launch videos you can see a flame tower to the side of the launch pad, like an oil rig. What is that and what does it do?
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#119
by
realtime
on 20 Nov, 2005 17:32
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Actually, a number of engineers I have spoken with believe that the SRB separation motors were the "straw that broke the camels back" for the big foam chunk that came off the PAL Ramp on STS-114.
Sounds like there's precious little "engineering margin" there. No way something that just barely makes it to orbit on a good day should be a structural element like a PAL ramp.
