Define and execute the R&D roadmap for solid propulsion subsystems, including grain design, liner chemistry (adhesion promoters, stress-relief layers), insulation architectures (elastomeric, phenolic, and composite ablative systems), and nozzle/case thermal protection, aligning laboratory choices with program ballistic targets, environmental constraints, and shelf-life objectives. Reporting directly to the Director of Engineering, this role leads a multi-disciplinary team of formulation chemists, materials engineers, and test specialists in the development, laboratory-scale testing, optimization, and pilot-scale transition of solid propulsion systems — spanning propellant formulations, bond-line liner systems, and internal thermal insulation.