#11
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Pad damage
What's NASA said about the damage?
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#12
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Pad damage
On Tue, 03 Jun 2008 00:24:08 -0500, Pat Flannery
wrote: If the subsurface material that the pad is built on has shifted or slumped from age and repeated launchings, then the whole pad may be dangerous to use without major reconstruction, pretty much from the ground up. ....Ok, if it's not a leaky pipe, then there's only one other thing it could be. Gophers. OM -- ]=====================================[ ] OMBlog - http://www.io.com/~o_m/omworld [ ] Let's face it: Sometimes you *need* [ ] an obnoxious opinion in your day! [ ]=====================================[ |
#13
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Pad damage
wrote: The solid propellant doesn't detonate and if a chunk came out, it would mean there is a problem with the SRM. Impossible with the liquids. The SRB propellant is pretty flexible anyway (something along the lines of a pencil eraser), so it wouldn't be prone to shedding a chunk. Early solid fuels could suffer fractures in their grains due to temperature variations, like taking them into very cold or hot environments, but that ceased to be a problem several decades ago with improved fuel mixtures. (This led to the odd heaters mounted inside of the cylinder that surrounded the Soviet Frog-1 artillery rocket as it rode around on its tank chassis in the cold Russian winter: http://www.fas.org/man/dod-101/sys/m...frog-1_002.jpg It may also account for why early Falcon AAMs were only carried internally by interceptors that operated at high and cold altitudes, though I'm not sure about that.) I'll tell you one thing though... if you want a _lot_ of thrust out of a solid fueled rocket engine, fire one with cracks in its fuel grain...you'll be amazed at the short burn time and high thrust. I tried out a ignition system on one of my homemade ones that involved a soda straw full of black powder inserted up the bore in the grain, and it shattered the grain when the black powder went off...and converted a planned burn time of around three seconds at around one hundred pounds thrust into a burn time of around one second at around five hundred to seven hundred pounds thrust - that shot out a exhaust flame around twenty feet long which set fire to the tree is it was being fired nozzle-up under. It was buried in the ground when this happened, and thank God the casing held... as otherwise it probably would have gone off like a landmine. Considering that the casing was a iron plumbing pipe this would probably not have been good from a shrapnel viewpoint... particularly since the test was going on around twenty feet from my childhood house. :-D Pat |
#14
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Pad damage
Pat Flannery wrote in
dakotatelephone: OM wrote: ...And weren't you also noting that the downlink audio had a significant vibration to it? I'm now wondering if there was more to it now, Brian. Some sort of resonance between the acoustic exhaust frequencies of the SRBs or SSMEs? If there was damaged caused, you'd expect it to be a lot more likely that the SRBs would be involved, due to their far greater acoustic shockwave output. Although you can explain the shed concrete panels in the interior of the flame trench (via the zipper effect after one shed in the high velocity exhaust flow from the SRBs), those shifted panels on the ramp that surrounds the flame trench proper are more worrying. If the subsurface material that the pad is built on has shifted or slumped from age and repeated launchings, then the whole pad may be dangerous to use without major reconstruction, pretty much from the ground up. That would be very time-consuming and expensive. Yes, possibly. Now imagine this scenario with a full-up Ares V at around 10 million pounds of thrust... --Damon |
#16
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Pad damage
Did all the water sprays actually work correctly do we know.
From the tank point of view, I'd say this is a red herring, myself. The fact is that this is a new tank and has been made with the mods from the ground up. What is not known of course is how much of the good performance of the modified tanks was due to the re application of foam after the mods being better than the normal application. I'd have expected a lot more damage to the tank than apparently there was if the debris from the pad had hit it, likewise with the orbiter of course. One tiny bit of torn blanket patch is hardly major damage, though one has to wonder if micro sized debris got into the oms mechanics and upset the back up striiing later in the ascent. I doubt anyone will be able to tell for certain till the orbiter gets back. Brian -- Brian Gaff....Note, this account does not accept Bcc: email. graphics are great, but the blind can't hear them Email: __________________________________________________ __________________________________________________ __________ "Brian Thorn" wrote in message ... On Mon, 02 Jun 2008 18:11:35 -0500, OM wrote: On Mon, 02 Jun 2008 22:22:50 GMT, "Brian Gaff" wrote: So then, what is the cause. Is it subsidence? Sounds like some ultrasound testing might be in order in the trench. ...And weren't you also noting that the downlink audio had a significant vibration to it? I'm now wondering if there was more to it now, Brian. And the disturbing increase in number and size of debris from a Tank that was supposed to be the "best yet" (but in reality looks to be the second worst since RTF.) Related? Probably not, but with NASA seemingly unwilling to acknowledge that the new Tank gave a far from stellar performance, its hard to just dismiss the possibility. Brian |
#17
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Pad damage
Be interesting to see if the srbs show any signs of damage and they are back
around now I think. I would not want to chance launching if the pad were unstable, but you would think that if it were, some cracks would, by now be showing in the top of it. Water could then get in and freeze assuming low enough temperatures. I plump for a less severe scenario of some underlying movement of soil etc, possibly caused by water and drying out cycles or similar, and the unzipping effect. The sms do fire for a long time before the solids are lit, long enough to loosen something ready for the shock wave of solid ignition to pulverise the loose material and lift off turbulence to scatter it far and wide. Brian -- Brian Gaff....Note, this account does not accept Bcc: email. graphics are great, but the blind can't hear them Email: __________________________________________________ __________________________________________________ __________ "Damon Hill" wrote in message ... Pat Flannery wrote in dakotatelephone: OM wrote: ...And weren't you also noting that the downlink audio had a significant vibration to it? I'm now wondering if there was more to it now, Brian. Some sort of resonance between the acoustic exhaust frequencies of the SRBs or SSMEs? If there was damaged caused, you'd expect it to be a lot more likely that the SRBs would be involved, due to their far greater acoustic shockwave output. Although you can explain the shed concrete panels in the interior of the flame trench (via the zipper effect after one shed in the high velocity exhaust flow from the SRBs), those shifted panels on the ramp that surrounds the flame trench proper are more worrying. If the subsurface material that the pad is built on has shifted or slumped from age and repeated launchings, then the whole pad may be dangerous to use without major reconstruction, pretty much from the ground up. That would be very time-consuming and expensive. Yes, possibly. Now imagine this scenario with a full-up Ares V at around 10 million pounds of thrust... --Damon |
#18
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Pad damage
Alan Erskine wrote: What's NASA said about the damage? http://www.spaceflightnow.com/shuttl...d3/index3.html http://www.spaceflightnow.com/shuttl...ad/damage.html Pat |
#19
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Pad damage
On Mon, 02 Jun 2008 20:18:07 -0500, Damon Hill
wrote: Rick Jones wrote in news:g2227b$pdk$1 : How much can come off an SRB without it being "fatal?" Could a chunk of propellant have come-loose and detonated somewhere in the tunnel? How about the liquid propellants? No. Most likely the pad's aged and deteriorated enough that it's started to fall apart under the stress. Imagine what a full-up Ares V might do to it with 10 million pounds or more of thrust... Way back in the 70's, I had the unique opportunity to walk through one of those trenches. I don't remember the lining being so clean appearing; seemed like it was pretty sooty. I read either on NYTimes.com or BBC.com that some of the blocks were blown 1800 feet away. Come to think of it, the number was also given as 550 meters, so it must have been the latter source. Pretty impressive. Quite the demonstration of the power of this thing. I'm sure they'll get it fixed up for a few million bucks in time for the next launch. Probably just an incidental but interesting expense in the big scheme of things. Dale |
#20
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Pad damage
"Pat Flannery" wrote in message
dakotatelephone... Alan Erskine wrote: What's NASA said about the damage? http://www.spaceflightnow.com/shuttl...d3/index3.html http://www.spaceflightnow.com/shuttl...ad/damage.html Pat Thank you, Mr Flannery. If you take a look at the second image from the second link, it looks like the flame trench itself has been pushed outward, squashing the concrete panels; like the crumpling seen when one squeezes a matchbox. |
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