Stainless Steel: Small amounts of stainless steel were used in the SR-71's construction, primarily in areas not subject to extreme temperatures. Stainless steel was chosen for its high strength and resistance to corrosion.
Honeycomb Structure: To achieve the necessary strength and rigidity while minimizing weight, many parts of the Blackbird's structure, such as its wings, fuselage, and tail, used a honeycomb structure. This structure consisted of a thin titanium outer skin with a hexagonal arrangement of honeycomb cells filled with an epoxy resin.
Other Materials: In addition to titanium and stainless steel, the SR-71 Blackbird used various other materials, including graphite composites, Inconel, and fiberglass, for specific components such as seals, gaskets, and radomes.
