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 @

"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

"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)

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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Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"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

"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?

"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

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.

On Fri, 17 Aug 2007 09:16:40 -0500, Craig Fink
wrote:


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.
Not being a NASA engineer, I don't have a perfect understanding of the
arc jet facility. But, from what I have read the facility seems to be
well able to mimic the heating and the aerodynamic behavior.
The problem with doing the repair is that it could cause earlier
heating because of early aerodynamic involvement. As is, the damage
is in a place that the structure can absorb the expected heating.
Doing the repair can cause the heating to begin earlier, be hotter,
and have an effect on the structure for a longer period of time.
Hope this helps.
Jim in Houston.

Contrary to popular opinion RN does not mean Real Nerd!

Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches"

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Jim in Houston wrote:
On Fri, 17 Aug 2007 09:16:40 -0500, Craig Fink
wrote:


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.
Not being a NASA engineer, I don't have a perfect understanding of the
arc jet facility. But, from what I have read the facility seems to be
well able to mimic the heating and the aerodynamic behavior.
The problem with doing the repair is that it could cause earlier
heating because of early aerodynamic involvement. As is, the damage
is in a place that the structure can absorb the expected heating.
Doing the repair can cause the heating to begin earlier, be hotter,
and have an effect on the structure for a longer period of time.
Hope this helps.
Jim in Houston.

Contrary to popular opinion RN does not mean Real Nerd!

Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches"


Just more a question than anything else. I am not nearly versed on any
of this to speak with any knowledge but here goes anyway. Have there not
been shuttle that came back from orbit with whole tiles completely
missing? Seems like early on they used to use high power telescopic
cameras to photograph the underside of the shuttle as it passed over
head, and it also seems to me I have seen of of those picture that had
tiles completely missing? like I said..just curious

Jim

On Fri, 17 Aug 2007 18:16:57 -0500, "James R. Jones"
wrote:



Just more a question than anything else. I am not nearly versed on any
of this to speak with any knowledge but here goes anyway. Have there not
been shuttle that came back from orbit with whole tiles completely
missing? Seems like early on they used to use high power telescopic
cameras to photograph the underside of the shuttle as it passed over
head, and it also seems to me I have seen of of those picture that had
tiles completely missing? like I said..just curious

Jim
Yes, many of the shuttles have made safe successfully landings missing
tiles or parts of insulation blankets. Most notably STS1 the first
Space Shuttle flight, the orbiter was Columbia. It returned with over
a dozen tiles missing. Other orbiters flew and returned sans tiles
with no harm to crew or vehicle. You could Google this subject, or
research it using the NASA web site for further information.
Jim in Houston.

Contrary to popular opinion RN does not mean Real Nerd!

Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches"

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Posted via a free Usenet account from http://www.teranews.com