Control Mechanism Strategies for Spin-Stabilized Projectiles

Report No. ARL-TR-4611
Authors: Frank Fresconi; Peter Plostins
Date/Pages: September 2008; 34 pages
Abstract: Spin-stabilized artillery munitions were originally designed to provide precise ballistic fire on long-range targets. Today the challenge is to utilize these ballistic munitions in military operations in urban terrain environments where significantly higher levels of precision are required to minimize collateral damage. One strategy is to retrofit these munitions with some level of low-cost precision. Unique challenges arise when munitions designed to be ballistically precise are guided. Projectile flight is often stabilized by a high spin rate, which induces complex dynamics. Flight mechanics are further aggravated by adding a control mechanism. The goal of this study was to provide a fundamental understanding of various control mechanism strategies for spin-stabilized projectiles. Flight control systems were developed and executed in a six degree-of-freedom simulation. Formulating a generalized model of a control mechanism allowed investigation of parameters such as control force magnitude, control axial location, control lift-to-drag ratio, and control force duration. Results showed that control authority linearly related to control force magnitude. Maximal control authority was obtained by placing the control mechanism at the rear of the projectile. The variation with axial location was also determined since these results were valuable for instances when the control was unable to be located near the projectile base. A lower lift-to-drag ratio of the control mechanism decreased control authority and maximum range. Lastly, the trade-offs associated with continuous and pulsed flight control systems were quantified. Physical explanations for the simulation results were provided.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2008