Experimental validation of open-motor derived ballistic models for propellant grain burn dynamics

This study evaluated the ballistic performance of four propellant grain geometries (star, Bate, finocyl, and rod-and-tube) using Open-Motor software, with results validated via static testing. Grain geometry dictates internal ballistics by governing the burning surface area, directly controlling chamber pressure, mass flow rate, and thrust. Star grain propellant geometry yields an intense progressive-short neutral-regressive profile with the highest peak pressure and thrust, but the shortest burn duration. Finocyl propellant grain geometry provides a balanced, mildly progressive-to-regressive-neutral profile. Bate and Rod and Tube propellant grain geometries, deliver neutral burn profiles by balancing internal and external surfaces. The Bate grain ensures high burn efficiency and steady pressure, while the rod-and-tube configuration maximizes burn longevity at a reduced thrust magnitude.
Ultimately, these findings demonstrate how geometric design can precisely tailor a motor's ballistic profile-optimizing either for the rapid, high-magnitude thrust needed by tactical interceptors, or the sustained, uniform thrust required for booster stages. Open-Motor is a suitable tool for evaluating diverse propellant grain geometries characteristic on motor ballistics.