Multiwall TPS - An emerging concept

Research on titanium multiwall used for thermal protection is reviewed. Continuing analytical and experimental studies yielding a fundamental understanding of the thermal and structural performance of the basic multiwall concept are presented noting that central to this understanding is a knowledge of the extensional behavior of the dimpled sheets since the thinner flat sheets will buckle and be relatively ineffective in supporting compressive loads. Results from radiant heating, aerothermal, vibration, acoustic and lightning strike tests are described as part of an effort to verify the performance of multiwall tiles under representative operating conditions. Flight tests of a large array of tiles are also planned as part of an orbiter experiments program. The research effort is being extended from flat all-titanium multiwall configurations limited to temperatures below 810 K to curved surfaces and higher temperature versions. Multi-wall concepts are found to offer the durability of metallic systems and to be mass competitive with the insulation system currently used on the Space Shuttle Orbiter.