Reed Riddle wrote in newsAMNdrriddleSPAM-
:

MA-25S was the ablator used on the X-15-A-2 when it flew it's maximum
speed flight (still the fastest flight of an aircraft, and of any winged
craft aside from the shuttle). The ablator stood up very well, aside
from the ventral stabilizer which was severely damaged due to shock
impingement heating. So, this is a well known substance, and as long as
the application is smooth (i.e. no shock waves) should enable the
orbiter to make it through a single re-entry. Application to the X-15
was a huge issue though...it will be interesting to see how well it
works in vacuum.

In fact, MA-25S was also the ablator used in the original 1979-80 shuttle
tile repair kit. It was abandoned because of a tendency to "foam up" in
vacuum. The current tile repair kit development team has apparently solved
that problem.

--
JRF

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