IMPACT AND PENETRATION BY L/D LESS-THAN-OR-EQUAL-TO 1 PROJECTILES

Calculations of steel target penetration by L/D less-than-or-equal-to 1 tungsten and tungsten alloy projectiles have been extended to L/D = 1/32 over the velocity range 1.5 to 5 km/s. The ratio of crater to projectile diameter tends to 1 as L/D decreases over this entire velocity range. For impact velocities of 1.5 and 3 km/s, penetration depth normalized by projectile length, P/L, increases with decreasing projectile L/D up to a maximum value and then decreases for still lower L/D. Experiments at impact velocities of 2 and 3 km/s confirm these results. For 5 km/s impact velocity, the calculations show P/L increasing with decreasing projectile L/D over the entire range 1/32 less-than-or-equal-to L/D less-than-or-equal-to 1. The projectile LAD for which the maximum P/L occurs appears to depend on the impact velocity. P/L generally scales with impact velocity as P/L approximately v(f(L/D)) where f(L/D) ranges from 0 for a long rod to, we believe, 2 in the limit as projectile L/D approaches zero. The calculations show for 1/8 less-than-or-equal-to L/D less-than-or-equal-to 1/2, P/L approximately v0.9; for L/D = 1/16, P/L approximately v1.5; and for L/D = 1/32, the new results give P/L approximately V1.9.