A self-transpiring hot skin for a hypersonic or reusable space vehicle
that can provide protection to the vehicle during short periods of
abnormally high heat flux (either planned in the flight profile or an
off-nominal event). The hot skin includes a ceramic composite structure
having an internal cavity that is coupled either to the insulating layer
or directly to the support structure of the hypersonic vehicle. The
internal cavity includes a material system that vaporizes, sublimes or
decomposes into a gas when the temperature exceeds the upper temperature
capability of the composite material. The gas transpires through the
outer layer of the composite material to provide cooling to the outer
layer below the upper temperature capability. Cooling may occur both by
conduction of heat from the composite material to the transpiring gas and
by the interaction of the transpiring gas with the boundary layer of
hypersonic flow over the outer surface, leading to a reduction of the
heat flux entering the surface.