Developmental Design and Ballistics Analysis of a Solid-Solid Fuel Torch (SFT) Rocket Motor

During the Space Shuttle program, NASA developed a Hybrid Solid Fuel Torch rocket motor test bed to conduct an extensive testing campaign on ablative insulation representative of a Solid Rocket Motor (SRM) environment. Following testing of this hybrid motor configuration, however, revealed unexpected slag plating and throat erosion, and further observations put into question if the hybrid motor was sufficient to replicate similar conditions representative of a Solid Rocket Motor environment suitable for insulation testing. With this, Solid-Solid Fuel Torch (Solid SFT) seeks to revitalize the program using existing 11” motor case hardware from the Hybrid Rocket Motor (HRM) program and test section hardware from the Hybrid Solid Fuel Torch (iSFT) testing to develop a fully solid test bed.

Following brief ballistics analysis, the original 5” motor grain size was deemed unsuitable due to not meeting the desired Key Performance Parameters (KPPs). As such, motor ballistics analysis was conducted using a Lumped Parameter Ballistics model with various motor configurations and geometries to select a new grain geometry that best fits the desired performance. Developmental design & analysis was also conducted to design a custom motor adapter and ablative nozzle to create a complete, integrated assembly for motor testing.