propellant grain

A propellant grain is the solid or sometimes composite material inside a rocket or missile that burns to produce the gases needed for propulsion. Its shape and composition are carefully designed to control how the fuel burns, ensuring steady and efficient thrust. As the grain burns, it turns into hot gases that rapidly expand and exit the engine nozzle, pushing the vehicle forward. The grain's design influences performance, stability, and the duration of the thrust, making it a crucial component in rocket engines.