What typically occurs to the center of gravity (CG) of a rocket during a solid rocket motor's thrust phase?

During the thrust phase of a solid rocket motor, the center of gravity (CG) of the rocket typically shifts backward. This shift occurs because solid rocket motors burn their propellant from the rear towards the front, resulting in a gradual reduction in the mass located at the front of the rocket. As the mass decreases at the front (the combustion chamber) and remains more concentrated toward the rear (the motor), the overall CG moves backward along the rocket's length.

Understanding the dynamics of a rocket's CG is crucial for stability and control during flight. A backward shift in CG can influence the rocket’s flight path and stability, requiring careful design considerations to maintain control authority and ensure proper aerodynamics. Therefore, a backward-moving CG aligns with the principles of rocket propulsion and mass distribution during flight.