"meep" wrote in message u...
http://www.cockeyed.com/inside/foam/foam.html

"Zoltan Szakaly" wrote in message
om...
When I looked at the video of how they simulated the foam block
colliding with the reinforced carbon carbon leading edge of the
shuttle, I noticed that behind the leading edge (which is a thin sheet
of RCC) there was nothing.

Isn't this highly irresponsible, in other words stupid? Any
homebuilder of kit airplanes knows that filling the cavity with foam
would greatly enhance the strength of the leading edge without
increasing the weight of the structure. The carbon fibers comprising
the composite sheet are strong in tension/compression but can be bent.
This lack of support from the inside was the direct cause of the hole
that the foam block punched in it.

Zoltan


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First of all I apologize for calling NASA irresponsible and stupid. I
unfortunately have had first hand experience and found common sense
lacking. I guess I could have better packaged my message or sugar
coated it or made it more politically correct.

The filling in a cavity like the one under discussion is important to
prevent the thin composite shell from breaking the exact way that it
broke in the test.

For filler material I can think of two candidates, one might be glass
sphere filled epoxy (microballon filler, bondo makes it) the other
candidate might be divinycell foam. During takeoff the foam would be
cold and it would support the RCC skin. During reentry the foam would
heat up and it would not provide support but it would be still better
than nothing. The epoxy and glass would probably take the heat
especially because it is already protected by the RCC skin. Both could
be applied through any small hole as a liquid and would solidify once
in the cavity.

Whatever else is being done to make the shuttle safer this cavity must
be filled before another flight is made. This is a no brainer.

An alternative protection method would be to coat the leading edges
with the same or similar foam on the outside. This could be sprayed on
before flight and it would cushion any impact during ascent and later
burn off during reentry.

Zoltan