Analytical and Experimental Comparisons of HTPB and ABS as Hybrid Rocket Fuels

Acrylonitrilebutadiene-styrene (ABS) thermoplastic is evaluated as a potential fuel for hybrid rocket motors and compared to the widely used fuel material Hydroxyl-Terminated Polybutadiene (HTPB). For this project Nitrous Oxide (N2O) is used as the matching oxidizer. ABS is widely mass-produced for non-combustion applications including household plumbing and structural materials. Analytical predictions for enthalpies of formation, products of combustion, and end-to-end motor performance are compared against staticburn test results for ABS fuel grain manufactured using Direct-Digital Manufacturing (DDM). The chemistry and performances of the ABS fuel grains are compared against fuel grains cast from HTPB. ABS grains were DDMfabricated from existing stock materials composed of 50:43:7 butadiene, acrylonitrile, and styrene mole fractions. The grains were tested and compared against HTPB grains of equal physical volume and dimension. Test results demonstrate a higher burn-to-burn consistency for ABS fuel grains, but slightly * Associate Professor, Mechanical and Aerospace Engineering Department, 4130 Old Main Hill, UMC 4130, Associate Fellow, AIAA. † Graduate Research Assistant, Mechanical and Aerospace Engineering Department, 4130 Old Main Hill, UMC 4130, Student Member, AIAA. ‡ Graduate Research Assistant, Mechanical and Aerospace Engineering Department, 4130 Old Main Hill, UMC 4130, Student Member, AIAA. 47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit 31 July 03 August 2011, San Diego, California AIAA 2011-5909