Use of Microspoilers for Control of Finned Projectiles

Abstract

Due to space limitations, cost restrictions, and performance challenges, the physical control mechanism 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.

Actuator Design and Flight Testing of an Active Microspoiler-Equipped Projectile

“…Note that, in comparison to the fourspoiler designs used previously in Refs. [13,14], the optimized geometry obtained in Ref. [15] exhibits an impressive 80% increase in control moment with only a 39% increase in drag.…”

“…Although not shown in Fig. 1, multiple sets of spoilers may be located around the projectile between each fin set and actuated independently for maximum control authority [13].…”

“…This paper considers one type of aerodynamic mechanism, termed microspoilers, which have been shown to be a promising control mechanism in previous investigations [13][14][15]. Microspoilers are small flow-effector mechanisms that extend orthogonally to the projectile body and are typically located between the rear stabilizing fin sets of a finned projectile.…”

“…The boundary layer-shock interaction between the projectile body, the microspoilers, and the rear fin set acts to produce rather large control forces and moments at relatively low drag penalty. Microspoilers were originally introduced as a candidate control mechanism by Dykes et al [13], who predicted the control authority induced by the mechanism using aerodynamic coefficients obtained through computational fluid dynamics (CFD). In a subsequent experimental study, Scheuermann et al [14] constructed a small-scale finned projectile with statically deployed microspoilers and obtained spark range measurements that were used to estimate aerodynamic coefficients.…”

Walking the Precession for Trajectory Control of Munitions

“…These moments can be generated by devices such as gurney flaps or spoilers [9] without creating a mass imbalance. These effectors are modeled here as control moments that are generated via asymmetric drag.…”