What manufacturing defect in solid fuels can act as a critical point of failure under flight conditions?

Answer

Small, hidden flaws like voids or inconsistent bonding can act as stress risers or premature ignition points.

Because the propellant is a heterogeneous cast material, invisible internal flaws can concentrate stress or provide an unexpected initiation point for combustion under the high pressures and temperatures encountered during launch.

What manufacturing defect in solid fuels can act as a critical point of failure under flight conditions?
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