From: patrick.eves@canrem.com (Patrick Eves)
Newsgroups: sci.military
Subject: uranium depleted shel
Date: 24 Jan 93 15:56:28 GMT
Organization: NCR Corporation -- Law Department


From Patrick Eves <patrick.eves@canrem.com>


D5>I'm writing about the A-10 Thunderbolt II (Warthog) and its 30mm GE GAU-8
D5>seven barrel cannon. I believe the shells to be a composite mixture of HE
D5>and depleted uranium. 

Actually, they're just DU, no HE content.  Kinetic energy alone does the
job.

With a muzzle velocity of approximately 3500 ft/sec
D5>it would seem that 2 1/2 pound shells would just ram their way through
D5>various types of armor. 

Your weight is way off.  The "shell" weighs 2 1/2 lbs., sure.  However, the
term "shell" refers to the complete round - case, projectile, and propellant.
If you want to get extremely technical, "shell" in this context is a misnomer.
"Shell" is used to refer to artillery ammunition, or shotgun ammunition, not
other types of ammo.  But we'll let this pass...<g>.  But I digress - the
DU projectile, weighing a few ounces, smashes through armour, using the same
principle that arrows do - maximum KE on minimum surface area.


But because of the shells composition, is it
D5>actually a fusion-reaction that would enable surprisingly deep penetration
D5>into armor?

Nope.  As stated earlier, it's simple kinetic energy overcoming the "surface
tension" of the molecules making up the armour plate.  Penetrating armour using
solid shot is the oldest example of armour piercing technology.  The English
bowmen at Agincourt used the same principle.  It's simply placing maximum force
on minimum surface area, a force great enough to overcome the ability of the
protecting medium to hold together, generated by a projectile that is strong
enough to deliver this force without shattering.  Depleted uranium penetrators
are simply the latest incarnation of this principle.  The requirement is
obviously for a very dense, very tough projectile.  Before DU, the ultimate was
tungsten, but the properties of DU, alloyed with ~2% molybdenum were discovered
in the mid '70s.  It's simply tougher and denser, thus generating more KE with
the same velocity, and it's able to survive the correspondingly more powerful
impact without shattering.  It's for this reason that DU is also used as a 
component of the composite armour array in the M1A1 (and subsequent versions)
Abrams tank.

The one area in which DU differs from conventional penetrators is in its after
penetration effect.  Traditional penetrators do their damage by ricocheting
about the interior of the tank, destroying vital components, setting off
ammo explosions (they are white hot from energy transferral), and killing
crew members (there's also the near-molten plug of armour to consider).  DU
adds to this after penetration effect with a tremendous incendiary effect caused
when finely divided DU particles combust upon contact with air (this is a
characteristic of DU, verifiable under lab conditions).  There might also
be one other effect (this is RUMOUR) - under the extreme stress of penetration,
the projectile releases its residual radiation in a "flash" effect.


D5>Theoretically, only 7 of these shells would be required to disable a tank
D5>(such as the Russian built T-72) but even this seems a little unrealistic.

I don't know where you got this "theory".  One shell in the right place would
be enough.  A hundred in the wrong place won't mean diddly.

D5>Would a tank really have armor thin enough that an A-10 Gatling-like gun
D5>could be effective?

You must remember that the 30mm shells are being fired from an aircraft.  This
means that they will strike the top of the tank.  Tanks are not armoured evenly,
because it isn't practical to do so.  The thickest armour is at the front, where
most threats are faced.  The sides have thinner armour, the rear and top the
thinnest.  The GAU-8 can pentrate the thin top armour, but there's no way it
can penetrate the frontal armour any modern MBT.   As an aside, because of
the fairly new possibility of top attack by aircraft, artillery shells, and
ATGMs, expect the next generation of MBTs to have significantly thicker
hull and turret top armour.

Regards,

Pat Eves
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