AbstractAluminum bumpers (Type 6061‐T6) with thicknesses of 0.1875, 0.125, 0.090, 0.063, and 0.032 inch have been subjected to impact with a 0.57 gram cylindrical steel projectile traveling at 9,400 to 21,700 ft/sec. In addition, the 0.032 inch bumpers were subjected to impact with 0.21 gram cylindrical steel projectiles traveling at 11,800 to 14,700 ft/sec. An aluminum (6061‐T6) vehicle hull was used in all experiments. For any given thickness of bumper, the vehicle hull was varied in both thickness and distance of separation from the bumper in order to establish the total weight and thickness of the structure necessary to prevent complete penetration by a given high velocity particle.It appears from the experimental data that spaced plates offer more effective protection from high velocity particles than a single plate of the same material and total mass. Moreover, it appears that thinner bumpers require less total weight in the vehicle to provide the same protection efficiency. This weight advantage provided by the thinner bumpers is reduced as the space between the bumper and plate is decrea