Simplified Projectile Swerve Solution for General Control Inputs

The swerve response of fin- and spin-stabilized projectiles to control mechanism inputs is sometimes not intuitive. This paper seeks to explain the basic parameters that govern the swerve of projectiles excited by control inputs. By modeling the overall effect of a generalized control mechanism as a nonrolling reference frame force applied to a point on the projectile, general expressions for swerve are obtained in terms of basic vehicle parameters. These compact expressions are used to show thatmaximum swerve response for a fin-stabilized projectile is achieved when the force is applied near the nose of the projectile, whereasmaximum swerve response for a spin-stabilized projectile is achieved when the force is applied near the base of the projectile. Nomenclature CMQ = pitch damping aerodynamic coefficient CNA = normal force aerodynamic coefficient CYPA = Magnus force aerodynamic coefficient D = projectile reference diameter Fc = magnitude of the applied control force g = gravity IP = pitch moment of inertia measured around an axis