Surface roughness effect on the aerodynamic characteristics of a blunt body

Conclusion The use of a smooth surface, for small projectiles, may lead to a reduction of drag at zero angle of attack. However, for specific configurations, especially those with blunt aft sections, an adverse normal force characteristic may develop, causing stability problems, similar to the one described by Schneider (1978). On the other hand, a skilful use of the separation-zone motion could serve as a maneuvering tool for unguided projectiles that are required to perform a search motion, and a built-in instability could maintain the desired motion.