Acrylonitrilebutadiene-styrene thermoplastic, widely mass-produced for noncombustion applications including household plumbing and structural materials, is evaluated and compared with hydroxyl-terminated polybutadiene as a potential fuel for hybrid rocket motors. Acrylonitrilebutadiene-styrene has several mechanical properties, including its ability to be fabricated into a wide variety of shapes using fused deposition modeling, which are very attractive as a potential hybrid rocket fuel. The acrylonitrilebutadiene-styrene grains were fabricated using fused deposition modeling from existing rapid-prototyping stock materials composed of 50∶43∶7 butadiene, acrylonitrile, and styrene mole fractions. The acrylonitrilebutadiene-styrene grains were burned with nitrous oxide as the matching oxidizer and compared for performance and consistency against fuel grains of equal size cast from hydroxylterminated polybutadiene and burned with nitrous oxide. Test results demonstrate a higher burn-to-burn consistency for acrylonitrilebutadiene-styrene, but slightly reduced overall performance. Methods for increasing the burn energy of the acrylonitrilebutadiene-styrene fuel grains were investigated. Equilibrium chemistry calculations conclude that, for a given oxidizer-to-fuel ratio, varying the butadiene mole fraction in the acrylonitrilebutadiene-styrene formulation has a significant effect on the propellant performance. A major result of this research is the demonstrated viability of thermoplastic as a hybrid rocket fuel grain material.

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This paper presents the design of the X-33 Flush Airdata Sensing (FADS) system. The X-33 FADS uses a matrix of pressure orifices on the vehicle nose to estimate airdata parameters. The system is designed with dual-redundant measurement hardware, which produces two independent measurement paths. Airdata parameters V [.Ix gradient with respect to vector x b[.] 3x partial derivative with respect to x American Institute of Aeronautics and Astronautics 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION OF REPORT OFTHIS

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