An unstable rocket can be stabilized by which action?

An unstable rocket can be stabilized by which action?

• A. Adding sufficient weight to the nosecone
• B. Removing sufficient weight from the nosecone
• C. Moving the fins sufficiently forward toward the nosecone
• D. Making the rocket sufficiently shorter

Answer: (A)

Stability in flight comes from the center of gravity being ahead of the center of pressure. When the CG is forward of the CP, aerodynamic forces create a restoring moment if the rocket tilts, bringing it back to the upright path. Adding weight to the nosecone moves the CG forward, increasing the distance between CG and CP, and thus increasing the static margin and the restoring moment. Removing weight from the nosecone would shift the CG backward, reducing the stability margin and making the rocket more prone to tipping. Moving the fins forward toward the nosecone would shift the center of pressure forward, which tends to destabilize rather than stabilize. Making the rocket shorter changes its aerodynamics in unpredictable ways and doesn’t reliably produce the necessary forward CG shift. So, the action that best stabilizes an unstable rocket is adding weight to the nose.

Stability in flight comes from the center of gravity being ahead of the center of pressure. When the CG is forward of the CP, aerodynamic forces create a restoring moment if the rocket tilts, bringing it back to the upright path. Adding weight to the nosecone moves the CG forward, increasing the distance between CG and CP, and thus increasing the static margin and the restoring moment.

Removing weight from the nosecone would shift the CG backward, reducing the stability margin and making the rocket more prone to tipping. Moving the fins forward toward the nosecone would shift the center of pressure forward, which tends to destabilize rather than stabilize. Making the rocket shorter changes its aerodynamics in unpredictable ways and doesn’t reliably produce the necessary forward CG shift. So, the action that best stabilizes an unstable rocket is adding weight to the nose.