Structural Strap Tension Measurements of a 6 meter Hypersonic Inflatable Aerodynamic Decelerator under Static and Dynamic Loading

摘要

To support NASA's goal of landing humans on Mars, development of technologies to facilitate the landing of heavy payloads are being explored. Current entry, decent, and landing technologies are not practical when utilizing these heavy payloads due to mass and volume constraints dictated by limitations imposed by current launch vehicle fairings. Therefore past and present technologies are now being explored to provide a mass and volume efficient solution to atmospheric entry, including Hypersonic Inflatable Aerodynamic Decelerators (HIADs). In the summer of 2012, a 6 meter diameter stacked-torus HIAD was successfully tested in the National Full-Scale Aerodynamics Complex's 40ft by 80ft wind tunnel at NASA Ames Research Center. During this test series the inflatable article was run in two different configurations at various combinations of torus inflation pressures, yaw angle (representing flight angle of attack), and wind tunnel dynamic pressure. The HIAD article was constructed in a stacked toroid configuration using inflatable torus segments composed of fiber-reinforced thin films, which were joined together with high strength textile woven structural straps to distribute the aerodynamic load throughout the inflatable structure. To better characterize the HIAD article's structural performance and provide key data to validate computational models, structural strap load measurement techniques were researched, developed, and implemented during static load testing and aerodynamic wind tunnel testing. This measurement system consisted of custom clevis pin and in-line strap tension loadceUs. The loadcell clevis pins were utilized at 8 of the 28 forward junctions between the structural straps and the centerbody of the 6 meter HIAD. Strap tension loadcells were integrated in-line with the HIAD at 21 strap locations. In this paper, both 6 meter configurations will be described along with the static load and wind tunnel test setups. Additionally, the custom structural strap measurement system will be described. Preliminary results from the static load testing and the wind tunnel testing for both configurations of the 6 meter HIAD will be presented.