Flight stability analysis of large aspect ratio explosively formed projectiles with fins

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Journal of Vibration and Shock ›› 2025, Vol. 44 ›› Issue (4) : 184-197.

SHOCK AND EXPLOSION

Flight stability analysis of large aspect ratio explosively formed projectiles with fins

LI Zhenzhen1,2,YANG Yongliang*1,WANG Yajun3,YANG Baoliang3,HOU Yunhui3,GUO Rui1

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Abstract

The flight stability of explosively formed projectiles (EFP) directly determines their impact orientation, velocity, and dispersion, which in turn affects the penetration performance of the EFP. To enhance the penetration power of hypersonic EFPs (Mach 4-7), a review of the current configurations and flight stability of EFPs was conducted. Models of EFPs with high aspect ratio tail skirts and corrugated fins were established, and a numerical method for calculating the aerodynamic parameters of hypersonic EFPs was developed and validated. The effects of structural parameters of finned EFPs—such as root height, tooth width, and solidity—on lift-to-drag ratio, center of pressure, and flight stability were analyzed. Additionally, the influence of structural asymmetry and roll motion on the static aerodynamic parameters of tail-skirted and finned EFPs was investigated. Based on this, the flight dynamics differential equations of EFP were established and validated. The effects of structural asymmetry and roll motion on ballistic radial displacement were analyzed. Additionally, the impact of liner material on the long-range velocity decay of spherical, tail-skirted, and finned EFPs was studied, and a quantitative analysis was conducted to assess how flight stability influences the residual velocity retention of EFPs. The study indicates that conventional stability criteria for finned projectiles remain applicable to the hypersonic air trajectory of EFPs. Introducing a low-speed roll motion through inclined corrugated fins significantly enhances the air trajectory dispersion of asymmetrical EFPs. The optimized finned EFP presented in this paper exhibits excellent flight stability and superior residual velocity retention, offering a standard configuration reference for designing high-penetration EFP warheads.

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Angle of attack oscillating / exterior ballistics / hypervelocity / aerodynamic characteristics

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LI Zhenzhen1, 2, YANG Yongliang1, WANG Yajun3, YANG Baoliang3, HOU Yunhui3, GUO Rui1. Flight stability analysis of large aspect ratio explosively formed projectiles with fins[J]. Journal of Vibration and Shock, 2025, 44(4): 184-197

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