Description: CFDRC and TRLA are proposing to develop, design, and test a mass-optimized isotensoid inflatable structure that makes maximum utilization of materials in providing tailored stiffness and rigidity for hypersonic entry vehicles. The proposed inflatable structure is a hybrid isotensoid pressure restraint employing an impervious cloth-reinforced barrier structure enveloped by an integrated array of high-tenacity tendons. The segregation of material functions provides greater design flexibility to meet stiffness and thermal protection requirements, while the external grid of cordage tendons provides mass- and load pathway-optimized containment of the structure's global pressure loads. The focus of the Phase I effort is to develop and demonstrate the isotensoid inflatable structure, complete with thermal protection hardware and load bearing attachment fittings for guidance and control hardware. The tendon materials will be evaluated for their strength at high temperatures while cloth structural materials will be evaluated for their stiffness and thermal insulation properties to produce a truly multifunctional structural enclosure. Integrated fluid-structure-thermal simulations will be conducted with CFDRC's validated tools to provide insight into the aerodynamic, material stress and localized heating effects on the model and to verify/optimize the proposed design. Phase II activities will focus on fabricating and testing a prototype of the proposed inflatable structure to validate the design robustness and capability for larger payload masses. Pre and post testing multidisciplinary simulations will be conducted to verify and optimize the design. Additional simulations will be conducted for verification under exact flight conditions.

Benefits: Additional application areas include analysis of space-based inflatable structures such as telescopes and mirrors, satellite solar panels and military reentry vehicles (inflatable decoys, etc) exposed to the atmosphere. The aeroelastic analysis of parachutes and parafoils and the analysis of high-altitude endurance airplanes with flexible wings will be improved. Further military applications include stabilization and deceleration of ordnance with attached inflatable decelerators.

The proposed integrated hypersonic inflatable entry system will have an immediate application in delivering large payload masses to the surface of Mars. This will reduce the number of launches required for the mission completion and total mission costs. The proposed technology will find direct applications with present and future NASA and industry inflatable structures programs, such as those seeking to provide deceleration and precision landing capability for large scale mass return from Earth orbit to Earth surface, or for missions to many of the potential atmosphere-endowed solar system destinations.