An unstable rocket can usually be made more stable by which action?

An unstable rocket can usually be made more stable by which action?

• A. Using a shorter nosecone
• B. Increasing the size of the aft fins
• C. Using a larger, heavier rocket motor
• D. Increasing the rocket diameter

Answer: (B)

Stability in a model rocket comes from keeping the center of gravity ahead of the center of pressure so that a tilt creates a restoring torque rather than a growing one. Pushing the center of pressure farther toward the tail increases that restoring moment when the rocket wanders off course. Enlarging the aft fins adds more tail-area where the airflow can exert force, moving the center of pressure rearward and, with the CG maintained forward, improving static stability. Shortening the nosecone reduces nose weight but moves the CG toward the tail, which tends to make stability worse. A larger motor adds weight toward the back, shifting the CG aft and also reducing stability. Increasing the diameter changes aerodynamics in less predictable ways and isn’t a reliable way to improve stability.

Stability in a model rocket comes from keeping the center of gravity ahead of the center of pressure so that a tilt creates a restoring torque rather than a growing one. Pushing the center of pressure farther toward the tail increases that restoring moment when the rocket wanders off course. Enlarging the aft fins adds more tail-area where the airflow can exert force, moving the center of pressure rearward and, with the CG maintained forward, improving static stability.

Shortening the nosecone reduces nose weight but moves the CG toward the tail, which tends to make stability worse. A larger motor adds weight toward the back, shifting the CG aft and also reducing stability. Increasing the diameter changes aerodynamics in less predictable ways and isn’t a reliable way to improve stability.