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Interpeting Tile Damage Test Results
Just one interpretation of the Tile Damage test results.
What an interesting hole in the tile. From the arc jet test conducted with a replica hole, it sure looks like a really nice vortex generator on the bottom of the Orbiter. The nice compression face in the hole seems to be generating a really nice vortex centered about the surface of the tile and moving into the wing as it flow aft. Here's the a picture of what arc jet damaged tile. http://www.nasa.gov/images/content/1...shannon_01.jpg The really nice 25-30 degree compression face is undamaged and intact after the test. All the rough edges have been smoothed, but the functioning surface is still there. As the relatively cool flow in the boundary layer reaches the leading edge of the hole, it make an inward turn. This is an expansion turn, so the flow cools. When the flow hits the compression face (90 degrees to the bottom surface of the Orbiter) it make a second turn. compressing the flow and heating it. But not enough to melt the compression face. The third turn, another compression turn up and out of the hole and into the boundary layer. Flowing down, right, and then up. Essentially flowing in a circle in the hole. Next, notice the wall between between the foam damage and the entry damage to the tile. Conditions here are not enough to melt the silicon tile, well maybe just a little bit right at the junction of the two compression turns. Notice the aft divet hole. So, the vortex generator will remain intact during entry. One expansion turn, two compression turns, generating a nice vortex centered at the surface of the tile. Next, the entry damage, the cut in the tile that is three times the size of the original hole. A vortex constrained and centered on the surface of the tile, bringing high temperature free stream flow impinging on the surface of the tile. Hypersonic flow from 1 to 2 inches above (well really below) the surface of the tiles, caught in a vortex and plunging through the relatively cool boundary layer, impinging on the tile. Where is this vortex going? Stuck between the surface of the tiles and the compressed hypersonic flow under the Orbiter, it sure looks like it want to go thru the Orbiter. Notice the end of the hole looks like a tunnel, the surface of the tile is intact, but the meat of the tile has been melted away. Right down to the felt isolator pad? Really trying to go thru the aluminum and into the wing. Compared to other random damage to the tiles, this is a much more dangerous ding. Essentially, a vortex generator has been added to the bottom of the Orbiter. It would be a really bad decision to leave such a thing un-repaired and fly an entry with fingers crossed. This brings to mind many, many more questions, and uncertainty about how well NASA is functioning (decision making) and their analysis of their current situation and to what end their technical bias is heading. JOO, -- Craig Fink Courtesy E-Mail Welcome @ |
#2
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Interpeting Tile Damage Test Results
"Craig Fink" wrote in message ... Just one interpretation of the Tile Damage test results. I wish they had a before and after picture of the tile. It looks like a lot of tile was removed during the simulated entry. I would think there is enough uncertainty in the test to justify a repair based on this much tile being removed. Danny Deger www.dannydeger.net |
#3
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Interpeting Tile Damage Test Results
"Craig Fink" wrote in message ... Here's the a picture of what arc jet damaged tile. http://www.nasa.gov/images/content/1...shannon_01.jpg I'd worry about the heat weakening the adhesive that holds the tile on. I'd think it would be bad if the damaged tile popped off during reentry. Jeff -- "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety" - B. Franklin, Bartlett's Familiar Quotations (1919) |
#4
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Interpeting Tile Damage Test Results
"Danny Deger" wrote in message ... "Craig Fink" wrote in message ... Just one interpretation of the Tile Damage test results. I wish they had a before and after picture of the tile. It looks like a lot of tile was removed during the simulated entry. I would think there is enough uncertainty in the test to justify a repair based on this much tile being removed. Florida Today has the pictures of the damage in orbit. You can compare that to the post test tile image. http://www.floridatoday.com/apps/pbc...ategory=news02 Look on the right side of the page for the Photo gallery link. Jeff -- "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety" - B. Franklin, Bartlett's Familiar Quotations (1919) |
#5
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Interpeting Tile Damage Test Results
"Jeff Findley" escribió en el mensaje ... "Craig Fink" wrote in message ... Here's the a picture of what arc jet damaged tile. http://www.nasa.gov/images/content/1...shannon_01.jpg I'd worry about the heat weakening the adhesive that holds the tile on. I'd think it would be bad if the damaged tile popped off during reentry. Can anyone of the experts in this group explain this...? http://science.ksc.nasa.gov/shuttle/...ion-sts-1.html Post-flight inspection of the Columbia revealed that an overpressure wave which occurred when the SRB ignited resulted in the loss of 16 heat shield tiles and damage to 148 others. 16 tiles lost and 148 damage and no problem in the entry!! and now everybody is worry about just one tile... ???? |
#7
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Interpeting Tile Damage Test Results
For a start, most of the damage was on the white tiles on the less critical
surfaces, and of course it was probably running quite light compared with the current vehicle. Brian -- Brian Gaff - Note:- In order to reduce spam, any email without 'Brian Gaff' in the display name may be lost. Blind user, so no pictures please! "Javi" wrote in message ... "Jeff Findley" escribió en el mensaje ... "Craig Fink" wrote in message ... Here's the a picture of what arc jet damaged tile. http://www.nasa.gov/images/content/1...shannon_01.jpg I'd worry about the heat weakening the adhesive that holds the tile on. I'd think it would be bad if the damaged tile popped off during reentry. Can anyone of the experts in this group explain this...? http://science.ksc.nasa.gov/shuttle/...ion-sts-1.html Post-flight inspection of the Columbia revealed that an overpressure wave which occurred when the SRB ignited resulted in the loss of 16 heat shield tiles and damage to 148 others. 16 tiles lost and 148 damage and no problem in the entry!! and now everybody is worry about just one tile... ???? |
#8
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Interpeting Tile Damage Test Results
"Brian Gaff" wrote in message news vortexes can easily cause tunneling, I'd have thought they ought to fix it. The point is made that the Shuttle will survive, but do they really want to have to strip off loads of tiles and maybe repair what is underneath? Seems to me that there is always going to be uncertainty. They have returned with worse holes, but they have had to do a lot of repair work to fix it afterwards. Brian One cited factor against repair on spaceflightnow.com was "astronauts have never applied STA-54 in the vacuum of space". Didn't they do an EVA test a while back of the repair putty? And if not isn't that something they should have tried? |
#9
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Interpeting Tile Damage Test Results
Danny Deger wrote:
"Craig Fink" wrote in message ... Just one interpretation of the Tile Damage test results. I wish they had a before and after picture of the tile. It looks like a lot of tile was removed during the simulated entry. I would think there is enough uncertainty in the test to justify a repair based on this much tile being removed. Hopefully the damage is just an arc jet test artifact that has a lot of study and understanding behind it and that it isn't something that they haven't seen before. Turbulent boundary layer, thin boundary layer, arc jet shock waves and not something else. |
#10
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Interpeting Tile Damage Test Results
"MichaelJP" wrote in message . .. "Brian Gaff" wrote in message news vortexes can easily cause tunneling, I'd have thought they ought to fix it. The point is made that the Shuttle will survive, but do they really want to have to strip off loads of tiles and maybe repair what is underneath? Seems to me that there is always going to be uncertainty. They have returned with worse holes, but they have had to do a lot of repair work to fix it afterwards. Brian One cited factor against repair on spaceflightnow.com was "astronauts have never applied STA-54 in the vacuum of space". Didn't they do an EVA test a while back of the repair putty? And if not isn't that something they should have tried? Apparently the EVA test was for the wash, not the STA-54. I am disappointed NASA had not used the STA-54 during an EVA before. I also gathered none of the onboard crew had ever worked with the STA-54 in training. Danny Deger |
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