Model: fragment masses and ballistic coefficients by component type, explosive delta-V, drag through the US Standard Atmosphere and the chosen winds. Illustrative, not a certified range-safety analysis.
Physics: 3-DOF point-mass flight on a rotating Earth with US Standard Atmosphere 1976 drag. Guidance flies a real return-to-launch-site sequence: boostback targets the landing zone through a predicted impact point, the entry burn steers, grid fins trim the descent and a single-engine hoverslam lands the stage.