Penetration equations for ogive-nose rods into aluminum targets

We present penetration equations for rigid, ogive-nose, rod projectiles that penetrate aluminum targets at normal impact. Comparisons of depth of penetration data and predictions from a previously published penetration equation derived from spherical, cavity-expansion methods show excellent agreement for striking velocities to 1800 m/s. We then identify a small parameter in the penetration equation, perform a power-series expansion, and obtain approximate penetration equations. These approximate equations are very accurate for striking velocities to 1300 m/s and display clearly the dominant problem parameters.