Re: New 'electrical active' Armour to defeat hand held anti-tank rounds

KH wrote:

> >http://www.observer.co.uk/international/story/0,6903,539143,00.html
> >
> >>Does anybody have an idea about how good it would be
> >>against kinetic energy penetrators ? As these are metal, too, they
> >>should have some effect.
>
>I guess Oerjan would be the one who might best comment on this. A
>recent posting on the www.tank-net.org forums claimed that the
>penetrator jet of a hollow charge is not actually liquid or gaseous,
>but still a solid.

Kinda-sorta. You could say that "HEAT jets are solid just like KE 
projectiles", but it is more accurate to say that both HEAT jets *and*
KE 
projectiles behave more or less like fluids - the differential equations

which govern their behaviour when they hit armour look far more like
those 
used for fluid dynamics than those used for solids.

However, they do have different shapes. KE rounds (and EFP slugs) are 
relatively short and fat (modern APFSDS rounds "only" have L/D ratios of

30:1) compared to HEAT jets, which makes the HEAT jet far more
vulnerable 
to lateral stresses. (Which is why early ERA types could defeat HEAT but

not KE while modern reactive armours are effective against both - the
early 
types weren't strong enough to stop KE.)

>Photos of hollow-charge damage I have seen all show
>rather clean small holes, which is not what I expect from a liquid
>hitting an object.

Never seen a narrow high-pressure water jet cut through a sand bank?
(...or 
the hull of a small boat, for that matter... <g>)

Later,

Oerjan
oerjan.ohlson@telia.com

"Life is like a sewer.
  What you get out of it, depends on what you put into it."