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Interpeting Tile Damage Test Results



 
 
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  #1  
Old August 16th 07, 12:42 PM posted to sci.space.shuttle,sci.space.policy,sci.space.history
Craig Fink
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Default 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
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  #2  
Old August 16th 07, 02:36 PM posted to sci.space.shuttle
Danny Deger
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Default 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  
Old August 16th 07, 02:45 PM posted to sci.space.shuttle
Jeff Findley
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Default 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  
Old August 16th 07, 03:26 PM posted to sci.space.shuttle
Jeff Findley
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Default 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  
Old August 16th 07, 05:55 PM posted to sci.space.shuttle
Javi
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Default 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... ????


  #6  
Old August 16th 07, 07:39 PM posted to sci.space.shuttle
Brian Gaff
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Posts: 2,312
Default Interpeting Tile Damage Test Results

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

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"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.

Danny Deger
www.dannydeger.net



  #7  
Old August 16th 07, 07:42 PM posted to sci.space.shuttle
Brian Gaff
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Posts: 2,312
Default 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  
Old August 17th 07, 11:01 AM posted to sci.space.shuttle
MichaelJP
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Posts: 107
Default 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  
Old August 17th 07, 03:16 PM posted to sci.space.shuttle
Craig Fink
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Posts: 1,858
Default 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  
Old August 17th 07, 03:48 PM posted to sci.space.shuttle
Danny Deger
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Posts: 530
Default 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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