To enable a crewed mission to Mars, precision landing capabilities of Entry, Descent, and Landing (EDL) systems must be improved. The need for larger payloads, higher landing sites, and controllability has motivated the National Aeronautics and Space Administration (NASA) to invest in new technologies to replace traditional rigid aeroshell systems, which are limited in size by the payload envelope of existing launch vehicles. A Hypersonic Inflatable Aerodynamic Decelerator (HIAD) is an emerging technology that provides an increased drag area by inflating the aeroshell to diameters not possible with rigid aeroshells, allowing the vehicle to decelerate higher in the atmosphere, offering access to higher landing sites with more timeline margin. To enable a crewed mission to Mars, future entry vehicles will require precision landing capabilities that go beyond heritage EDL guidance strategies that utilize fuel-intensive and error-prone bank reversals. A novel Direct Force Control (DFC) approach of independently controlling the lift and side force of a vehicle that utilizes a HIAD with an aerodynamic shape morphing capability is proposed. To date, the mechanisms and controls required to morph an inflatable structure to generate lift have not been explored. In this dissertation, novel morphing HIAD concepts are investigated and designed to satisfy mission requirements, aerodynamic tools are built to assess the aerodynamic performance of morphed blunt body shapes, and a structural feasibility study is performed using models correlated to test data to determine the forces required to generate the desired shape change based on a crewed mission to Mars. A novel control methodology is introduced by applying a unique DFC strategy to a morphing HIAD to enhance precision landing capabilities of EDL systems, and the ability of a morphing HIAD to safely land a vehicle on Mars is assessed by performing a closed-loop feedback simulation for a Mars entry trajectory. Finally, a control mechanism is demonstrated on a small-scale inflatable structure. Conclusions and contributions of this research are presented along with a discussion of future research opportunities of morphing HIADs. / PHD / A Hypersonic Inflatable Aerodynamic Decelerator (HIAD) is a reentry vehicle designed to inflate the aeroshell to diameters outside of the payload shroud to decelerate the vehicle higher in the atmosphere, offering access to higher landing sites with more timeline margin. To enable a crewed mission to Mars, the landing accuracy of a HIAD must be significantly improved beyond heritage bank angle control approaches that are fuel-intensive and prone to errors. A novel Direct Force Control (DFC) approach is proposed that permits direct control of the angle of attack and sideslip by morphing the inflatable shape of the HIAD to enable its precision landing capabilities. A morphing HIAD concept is proposed in this dissertation to satisfy the requirements of landing humans successfully on Mars. Aerodynamic tools are built to assess the aerodynamic performance of morphed blunt body shapes, and structural models correlated with test data are created to determine the forces required to generate the desired shape change. Novel DFC methodologies are introduced and applied to a morphing HIAD system, a motor sizing study is performed to compare the total energy usage and cost and weight estimates of the morphing HIAD to heritage control systems, and a Mars entry trajectory simulation is performed to assess the capability of a morphing HIAD to safely land a crewed vehicle on Mars. Finally, a control mechanism is demonstrated on a small-scale inflatable structure. Conclusions and contributions of this research are presented along with a discussion of future research opportunities of morphing HIADs.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/96194 |
| Date | 29 June 2018 |
| Creators | Slagle, Adam Christopher |
| Contributors | Mechanical Engineering, Fuller, Christopher R., Dunn, Barry J., Southward, Steve C., Philen, Michael K., Roithmayr, Carlos Michael |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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