What parts of the rocket did not change in October sky during each experiment?

In "October Sky," certain parts of the rocket remained consistent throughout the experiments, such as the body structure and the propulsion system design. The team typically used similar materials for the rocket casing, which allowed for a standard shape and weight distribution. Additionally, the fins and nose cone often stayed the same, as these components were essential for stability and aerodynamics. Despite variations in fuel and design tweaks, the foundational elements of the rockets provided a reliable basis for their experiments.