Glass armour and shaped charge jets

115 mm shaped charges were fired at a constant built-in standoffs of 3 caliber against on both sides with steel plate covered glass targets from 0 degrees to 60 degrees NATO angles. The residual jet tip velocities and the disturbed jet regions have been analyzed from double flash X-ray pictures of the residual jet behind the target. Surprisingly under small angles the tip regions and under large angles the residual jet velocity regions have been more disturbed. This can be explained by the fact that under small angles the closure effect of glass is efficient but no more under large angles. But here the cover plates of the glass sandwich are effective as bulging armour. From the penetration time measurements, compared to the theoretical penetration potential, and together with the jet fan the jet velocities, which are no more perfectly penetrating can be defined. From this can be derived an induction time or how fast the armour will start to interfere with the passing jet.