Path: utzoo!utgpu!watserv1!watmath!att!cbnews!military
From: c162-bv@zooey.berkeley.edu (Iain McClatchie)
Newsgroups: sci.military
Subject: Re: depleted uranium ammunition
Message-ID: <15570@cbnews.ATT.COM>
Date: 14 Apr 90 04:10:55 GMT
Sender: military@cbnews.ATT.COM
Organization: University of California, Berkeley
Lines: 42
Approved: military@att.att.com



From: c162-bv@zooey.berkeley.edu (Iain McClatchie)
In article <15374@cbnews.ATT.COM> you write:
>  I've already referred to DU's hardness, but I'm surprised nobody's mentioned
>it before:  What good is a soft penetrator?  That DU rounds can pass all thess
>way through a tank is due as much to DU's hardness as to its density.

It takes about 600 Calories per gram to vaporize water from room temperature,
and water has an enormous heat capacity. The same heat per gram will heat
steel 3000 degrees Celsius. This amount of heat corresponds to 2240 m/s impact,
or 7350 ft/s.

The M1 tank fires it's DU rounds about that fast, doesn't it?

[mod.note:  I think the MV for the APFSDS-DU ammo is about 5000 fps. 
- Bill ]

My point here is that it seems the energy converted into heat on impact is
going to melt the penetrator. Hmmmm....

[mod.note.2: First, not all the energy is converted; the projectile
retains some velocity.  Second, most of the lost energy is absorbed in
the deformation of the armor, and would heat the tank, not the projectile.
- Bill ]

Could you clear something up for me? The M1 has a BIG (> 150mm) gun to shoot
its round through the armor of an enemy tank. I think the M1 round is something
like 3 pounds. The A-10 has a much smaller gun (like 30mm). It seems to make up
with quantity. I can understand how quantity can mitigate bad accuracy, but
it's not clear to me how a bunch of little bullets can get through armor that
can stop each one. If the armor can't stop them, then why does the M1 need
such a big gun?

[mod.note.3 (this is getting to be a habit 8-): The M1 mounts a 120mm gun
(105mm on the original version).  The A-10 wins by not having to penetrate
as much armor; attacking from altitude allows it to hit the much thinner
deck armor, and defeats the slope of the frontal armor, which is inclined
to nearly horizontal on modern tanks. - Bill ]

-Iain McClatchie
c162-bv@zooey.berkeley.edu