1. Hybrid Engines Conventional hybrid vs. “reverse” hybrid 4 Main Components of Hybrid Engine Ignition system Fuel chamber www.aspirespace.org.uk

2. PMMA or HTPB? PMMA (Poly-Methyl Methacrylate) or plexiglass HTPB (Hydroxyl Terminated Poly-Butadiene) or rubber Properties: Pros and Cons of HTPB vs. PMMA

3. Cost Evaluation PMMA is sold as either extruded or cast –D o = 0.05 m, D i =0.044 m, L = 0.5 m, t = 0.03 m is $202.00 –D o = 0.03 m, D i = 0.024 m, L = 0.5 m, t = 0.03 m is $234.00 HTPB is a two part mix ($56) –one part thermoset elastomer –one part diisocyanate