From: Jim Calpin <calpinj@mitre.org>
Newsgroups: sci.military.naval
Subject: Re: effect of explosives on armor
Date: Tue, 13 May 1997 12:08:44 -0400

Paul J. Adam wrote:

> >Agree with statement concerning penetrator materials, but concerning shape
> >charge liner:  Have you ever heard of one *without* a liner (not counting
> >pre-WWII or research models)?
>
> No. I was talking about just using a _big_ blast warhead: cave in the
> armour, failing that do maximum damage to the superstructure.
>
> The liner makes a big difference to charge performance. There were some
> unlined HEAT warheads in World War 2, don't know when the liner became
> properly appreciated.
>
> I read that one of the best materials is gold: copper's nearly as good,
> though.

The general rule of thumb for shaped charge liners is the denser the
material, the better.  Gold is among the best performers, but a tad
bit expensive for everyday use.  DU works well, but is a little
bit more difficult to work with.  Copper is a good, cheap, and easy
compromise, and is the most common liner material.  (It, unlike
DU, is also amenable to regular and accurate deep-drawing procedures,
necessary for precision shaped charges.)  It should also be noted that
improvements in shaped charge performance are almost always tied
to improvements in the precision of the liner's shaping and centering.

WRT charges with no liners, the penetration is markedly reduced.  Also,
unlike charges with liners, maximum penetration occurs at zero
standoff.  For ann excellent comparison of performance of charges
with and without liners, and against steel and lead targets, see
the definitive work on the mathematics of shaped charges: "Explosives
With Lined Cavities" (Birkhoff et al, Journal of Applied Physics,
June 1948.)

Lastly, as has been discussed many times before, shaped charges do
no cut, burn, or melt there way through armor.  Hypersonic penetration
is purely a fluid-on-fluid event.

-Jim C.