Use of Microspoilers for Control of Finned Projectiles

Due to space limitations, cost restrictions, and performance challenges, the physical controlmechanism on a smart projectile plays a central role in the overall system design.Many different smart projectile control mechanisms have been created including aerodynamic-based mechanisms such as movable canards, propellant-based mechanisms such as squibs, and inertia-based mechanisms such as internal moving masses. The work reported here considers small microspoilers located between rear fins of a finned projectile to create aerodynamic load changes to enable projectile control. In particular, boundary-layer shock interaction between the projectile body, fins, and microspoilers provides a multiplicative effect on controllable forces and moments induced by microspoiler activation. A parametric study varying the microspoiler configuration is conducted to examine the level of control authority possible for this control mechanism concept. Results indicate that relatively small microspoilers located between fins generate substantial control authority that is capable of eliminating impact errors caused by muzzle jump, aerodynamic uncertainty, and atmospheric winds. These conclusions are based on computational fluid dynamic predictions of the effect of microspoilers on air loads coupled to a rigid six-degree-of-freedom projectile trajectory simulation. Nomenclature a = speed of sound for air, ft=