[repost] How does anti-tank missile work?

Question

Cumulative action anti-tank missile consists of two blocks
of explosives lined with metal plates inclined by angle α to each other.
When missile moving with speed Va = 500 m/s
hits the armor, the exoplosives are detonated, and the plates
are propelled towards each other, with equal speeds Vo = 1000 m/s.

http://alexandersemenov.tripod.com/jet/index.htm

The plates collide and produce cumulative jet moving
with speed Vj, which easily pierces the armor.

What should be the value of angle α to achieve relative
velocity of the jet with respect to the armor Vj + Va = 5,000 m/s?

Assume that metal plates behave like ideal incompressible fluid.

Cross-section of real warhead can be seen here:
http://www.inert-ord.net/atrkts/bazoo/

The real things have cylindrical symmetry of course.
In additon they are disigned to spit all 100% of metal forward, explisives gas acting as outer layers.
But why complicate things, when basic
physical principle is so simple.

Answer 1

Aren't those things axisymmetric?