Experiments with jacketed rods of high fineness ratio

Cylinders of high fineness ratio can show severe integrity and stability problems during acceleration and free-flight phase. The paper describes a method to overcome these problems by adding an envelope to the slender cylinder thereby augmenting the stiffness under flexure. Theoretical considerations treat the pros and cons of jackets with different Young's moduli while looking at various parameters such as maximal deflection, total mass as well as muzzle and impact velocity.

Special emphasis is given to the terminal ballistic efficiency which has been tested using jacketed model penetrators made of tungsten heavy metal with carbon-fibre reinforced plastic (CFRP) and steel envelopes. Some experiments were carried out with cannon-launched CFRP-jacketed tungsten rods of aspect ratios from 45 to 60 being accelerated up to 2000 m/s. In other penetration tests L/D=25 and 40 jacketed penetrators were shot onto homogeneous semi-infinite RHA targets and also spaced targets at 60° incidence at velocities up to 2500 m/s by aid of a light-gas gun.

The experiments with jacketed model penetrators of 3 and 4 mm diameter at high impact velocities showed a good penetration power into homogeneous targets, whereas there is a loss of penetration efficiency into spaced targets of 20% and more. Furthermore it seems that the relative thickness of the jacket should not exceed a certain value in order not to risk a detrimental effect on the penetration performance.