 This has led to the current designs which resemble a long metal arrow.For monobloc penetrators consisting solely of one material, a perforation formula devised by Wili Odermatt and W. Lanz is able to calculate the penetration capability of an APFSDS round.In 1982, using some ideas from gas dynamics, pioneering analytical investigations with experiments on penetration into targets  led to conclusions about the efficiency of impactors (penetration is deeper) with unconventional three-dimensional shapes .