What was the skin of the a/c? I would surmise titanium but would be quite interested in knowing if another alloy was used. Your work must have been fascinating.
Titanium aluminides and carbon-carbon composites.
I was at Gen Dynamics & a guy gave me a six inch leading edge Shuttle wing. It weighed a ton. Then he gave me an X-30 identical piece. Light as a feather & sustained MANY times more heat.