Jake McGuire wrote:
On Aug 12, 9:19 pm, Pat Flannery wrote:
Sylvia Else wrote:

"In a stroke of luck, they're right beneath the aluminum framework for
the right wing, which would offer extra protection during the ride
back to Earth."
Given that the aluminium (yanks don't know how to spell) would melt, I
find this an odd usage of the word "luck".
I think the concept is that the reentry plasma would have to get through
the skin and framework it's attached to before getting inside the wing's
internal structure. IIRC, there has been a case before where a burning
of the aluminum skin has occurred due to tile damage, and although it
was expensive to repair, it didn't do major damage to the Shuttle.

Naah. The damaged tile will cause intense heating in a localized
area, which will get conducted into the rest of the structure. If it
was a patch of skin, the heat could not be conducted away very
quickly, so the skin would get hot enough to melt. The stringer will
conduct the heat away quickly enough that the structural temperatures
won't get high enough to cause a problem, or at least that seems to be
the theory.

Which just goes to show that the theory about the best way to get an
answer on USENET is not to ask a question but to make an incorrect
assertion is still valid...

-jake


As somewhat of an aside, I came across this document about the thermal
protection system

http://ntrs.nasa.gov/archive/nasa/ca...1993023009.pdf

On page 9 it tabulates the number of distinct damage locations sustained
by the thermal protection system on each mission. On some missions it
approaches 300.

Sylvia.