Dumb Question About Foam Test

"Brian W" wrote in message

Which is what I was thinking. Wasn't the piece that US Space Command
picked
up the size of a T-Seal?

If memory serves me well, yes.

BTW, here's a direct link to one of the videos of the SWRI test:

http://spaceflight.nasa.gov/gallery/...wri_070703.mov

Jon

"Brian W" wrote in
news:3f0c88ab$0$28277$afc38c87@:

During the last foam test, it looks like the entire foam piece
breached the RCC panel causing the now well viewed 16-inch hole. But
on the launch video, it's clearly shown that the debris from the
impact travels down the bottom side of the wing. I'm assuming this
isn't RCC debris since I'm guessing most of that would remain inside
of the wing. So wouldn't the last test not be 100% accurate since the
debris is moving down outside of the wing area.

This has already been discussed recently (whatever happened to newbies
doing Google searches to see if their question has already been answered?),
but here goes anyway...

Ideas anyone?

Right: the most recent test did not exactly replicate the STS-107 scenario.
There were two impact tests using real RCC panels. One was a corner strike
on panel 6, the other a full-side strike on panel 8. The first test
resulted in a small crack in the RCC and a lot of external foam debris. The
second test resulted in a 16-inch hole in the RCC and much of the foam
debris inside the hole.

The aerothermal evidence suggests that the STS-107 hole was smaller (6-10
inches) than that seen in the second test. It is reasonable to say that the
actual flight scenario was somewhere in between the two tests: worse than
the first test, but not as bad as the second. So the debris seen exiting
the bottom of the wing was most likely foam fragments.

You cannot expect these tests to exactly replicate the in-flight scenario
since RCC panels are rare, expensive, and take a long time to make. This
last test, for example, cost $3.4 million to run, since the five RCC panels
used in the test cannot be used again. The best you can expect is for your
tests to "bracket" the expected damage, as happened here.
--
JRF

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Jorge R. Frank wrote in message
...

Right: the most recent test did not exactly replicate the STS-107
scenario.
There were two impact tests using real RCC panels. One was a corner
strike on panel 6, the other a full-side strike on panel 8. The first
test
resulted in a small crack in the RCC and a lot of external foam debris.
The second test resulted in a 16-inch hole in the RCC and much of the
foam debris inside the hole.

The aerothermal evidence suggests that the STS-107 hole was smaller
(6-10 inches) than that seen in the second test. It is reasonable to say
that the actual flight scenario was somewhere in between the two tests:
worse than the first test, but not as bad as the second. So the debris
seen exiting the bottom of the wing was most likely foam fragments.

It is also reasonable to say that although a foam strike may have
contributed to the loss of Columbia, one cannot conclude yet from
the totality of the evidence that a foam strike was the only cause,
or even the most likely cause.

The best you can expect is for your tests to "bracket" the expected
damage, as happened here.

You're talking about foam damage. I have seen no evidence yet to
prove that the lower bound of such damage precluded a landing.
On the other hand, I have seen no evidence yet to prove that the
upper bound of such damage is reasonable based on ascent data,
or even on the OEX entry data, for that matter.

--
John Thomas Maxson, Retired Engineer (Aerospace)
Author, The Betrayal of Mission 51-L (www.mission51l.com)

Jorge R. Frank wrote:

The first test
resulted in a small crack in the RCC and a lot of external foam debris. The
second test resulted in a 16-inch hole in the RCC and much of the foam
debris inside the hole.

The aerothermal evidence suggests that the STS-107 hole was smaller (6-10
inches) than that seen in the second test. It is reasonable to say that the
actual flight scenario was somewhere in between the two tests: worse than
the first test, but not as bad as the second.

Isn't the working theory also that the object later tracked moving away from
the orbiter was a section of RCC? This fits in with the idea that the impact
caused cracking but not immediate seperation, and that later thermal cycles
completed the crack and released the RCC fragment. So the Columbia event
*looked* like the first test but had a final effect on the RCC similar to the
second test.

JGM

(JGM) wrote in
:

Isn't the working theory also that the object later tracked moving
away from
the orbiter was a section of RCC? This fits in with the idea that the
impact caused cracking but not immediate seperation, and that later
thermal cycles completed the crack and released the RCC fragment. So
the Columbia event *looked* like the first test but had a final effect
on the RCC similar to the second test.

True. The damage could have been anywhere in between.


--
JRF

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check "Organization" (I am not assimilated) and
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"Brian W"
During the last foam test, it looks like the entire foam piece breached the
RCC panel causing the now well viewed 16-inch hole. But on the launch
video, it's clearly shown that the debris from the impact travels down the
bottom side of the wing.......So wouldn't the last
test not be 100% accurate

I think I can explain this.

There was no existing data on the ability of the RCC to take a foam strike, as
in zero.

Technically, the tests done at SWRI were not done to determine or re-create what
happened to Columbia. The test was done to see what happens when foam hits RCC.
It is a small difference, but accurate as I understand it.

Why not recreate the actual event? Well, if you are starting from zero data,
then you have to first show that RCC damage is plausible. Once you have shown
that foam *can* damage RCC, then it is possible to proceed to the particulars.