Advanced Foam Core Composite Insulation for Extended Range Hypersonic Vehicles

Hypersonic flight requires the development of insulating materials with a combination of thermal conductivity, density, and structural integrity that is beyond the capability of materials currently in use. In previous thermal protection system work for DoD and NASA, Ultramet developed a highly insulating and lightweight material by combining an open-cell foam skeleton with an ultralow-density aerogel filler material. The foam serves as an easily machinable structural reinforcement for the low-strength aerogel insulator and defines the shape of the component. The combined density of the foam/aerogel composite insulator is <0.07 g/cm3 (4.4 lb/ft3); processing is economical and is readily scalable to 2 × 2 × 12" thick flat and curved shapes. The material has a thermal conductivity of only 0.25 W/m•K at 2000ºF and 0.8 W/m•K at 3600ºF, and has demonstrated the ability to maintain large thermal gradients for extended periods. Equally as important for hypersonic vehicle applications, the foam/aerogel insulator has a use temperature approaching 4000ºF, nearly 1000ºF greater than conventional oxide-based insulators. The previous work has focused on enclosing the insulator within a free-standing structural shell. The potential exists to increase the strength and stiffness of the foam reinforcement such that it can be integrated with a carbon-based aeroshell, creating a load-bearing sandwich structure, while still maintaining acceptable density and thermal conductivity. In this project, Ultramet will team with Materials Research & Design (MR&D) for thermal-mechanical modeling and attachment design methodologies, and Ocellus for aerogel insulation processing, to develop and demonstrate a sandwich panel core insulator.