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

Sorry for the delay, Ryan - I got home too late last night to read any 
emails :-(

Ryan Gill wrote:

 >>Once again, there is no such thing as a "plasma jet" from a HEAT
 >>warhead. Fortunately for the operation of this electrical armour,
 >>metal doesn't need to be in a plasma state in order to close a
 >>circuit.
 >
 >Ok, sorry to drag up an old conversation here. What is the jet from a
 >shaped charge. What material state best describes it and it's 
characteristics?

For metals at least (*) it is best described either as a solid or as a 
liquid, depending on exactly what characteristic you're after: it *is* a

solid, but it is under such a high strain that ydrodynamics equations
give 
a better model for how it deforms than the normal solid-state mechanics 
equations do (IOW, it *behaves* roughly as if it were an incompressible 
inviscid liquid).

(*) We don't use any of the more exotic liner materials like glass or 
ceramics in our warheads, so I have no experience with how they behave -

but I'd be somewhat surprised if they behaved just like metals :-/

If you haven't already, read the paper Aaron quoted ( 
http://www.dean.usma.edu/math/research/msce/11th_AUTS/papers/Walters.pdf
) 
- it is one of the best "shaped charges for dummies" texts I've seen to 
date. It doesn't go into how reactive armours work, but it covers the 
important aspects of the shaped charges themselves without losing either

itself or the casual reader in complicated maths... and it explicitly 
punctures a number of general-public misconceptions along the way <g>

(BTW, Aaron, jumping in front of my response doesn't hurt as long as
you're 
right and thus save me from extra typing! :-) )

As for the Jane's quote Randall posted, well... it wouldn't be the first

time Jane's got something seriously wrong :-/

Later,

Oerjan
oerjan.ohlson@telia.com

"Life is like a sewer.
  What you get out of it, depends on what you put into it."
-Hen3ry