Flight Behaviors of a Complex Projectile using a Coupled CFD-based Simulation Technique: Closed-loop Control

This paper describes a study to understand the pitch, roll, and roll-pitch-yaw behavior of a canard-controlled, fin-stabilized projectile. Numerical computations were performed for this projectile for open-loop control maneuvers using an advanced coupled computational fluid dynamics and rigid body dynamics technique. For canard control cases, the coupled approach automatically takes into account the canard flow interactions with the rear fins. Aerodynamic models including the roll and pitch/yaw interaction moments were proposed. Numerical results from the coupled method were used in parameter estimation algorithms to validate these aerodynamic models and quantify the aerodynamic coefficients for lower angles of attack. Flow separation and time-dependent phenomena detected in the coupled computations at higher angles of attack are discussed. The underlying flight behaviors encountered in pure pitch and pure roll primarily explain the motions in the full roll-pitchyaw flight. The results obtained from these techniques permit high-fidelity assessment of the maneuvering flight performance and supply aerodynamic information critical to flight control design.