DU pyrophoricity

["Phil Hypes" <laradcon@HOTMAIL.COM>]

No, Ted is not correct (nothing personal) if he's saying the pyrophoricity 

of DU is important to it's anti-armor capabilities.  Folks, when ANYTHING 

traveling at kilometers per second passes through a sheet of metal, hot 

metal fragements are going to be produced, if only from the displacement of 

the armor metal itself.  Those fragements of displaced armor alone, when put 

in contact with flammable materials (fuel, gunpowder, you know, tank 

stuff!), causes secondary fires and explosions.  That is the primary 

mechanism for defeating an armored vehicle with any penetrator, be it a WWII 

type tungsten round, or a modern DU round.



Unless they lied to me and doctored photographs during my Armor Officer 

Basic Course (Fort Knox is lovely in the winter!), DU rounds often exit the 

far side of an armored target with virtually all of their mass intact.  

That's what makes DU a good penetrator.



The "How stuff works" description is mostly accurate, but it does have a 

couple of errors and omissions.  The plastic sabot isn't flimsy; it's stong 

enough to seal the propellant gasses at high enough pressures to drive a DU 

round out of the barrel at unmentionable speeds.  It comes apart because 

it's designed to after it leaves the barrel.  The description also doesn't 

specify where the heated fragments of metal come from.  They come primarily 

from the displaced armor, not the DU itself.  The heat comes from friction 

and pressures that tear the metal apart, not DU pyrophoricity.  I'm not 

denying that DU is pyrophoric, but I am stronly denying that that fact has 

anything significant to do with it's anti-armor capabilities.  A few 

milligrams or grams of material that smoulders when powdered is a fart in a 

whirlwind compared to everything going on inside a DU-penetrated tank.



Phil Hypes

Los Alamos Radiation Consultants

laradcon@hotmail.com

505.920.9712



----Original Message Follows----

From: "Darnell, Peter A." <pkd0@cdc.gov>

Reply-To: "Darnell, Peter A." <pkd0@cdc.gov>

To: radsafe@list.vanderbilt.edu

Subject: RE: Letter to Congressman McDermott by Leuren Moret

Date: Fri, 7 Mar 2003 14:31:46 -0500



I hope I'm not beating a dead horse here, but Ted is correct.  DU

penetrates, releases particles that burn and penetrate out.  While the human

part of me feels for those on the receiving end of these munitions, I'm very

glad the US has them.  Here's an excerpt from "How Stuff Works" on the M1

Tank:



"Sabot

Sabot rounds work like a basic arrow. They don't have any explosive power;

they penetrate armor with shear momentum. The heart of the sabot round is

the penetrator -- a narrow metal rod (typically depleted uranium) with a

pointed nose on one end and stabilizing fins on the other. Before the round

is fired, the rear part of the penetrator is attached to a propellant case,

and the front part is attached to the sabot structure. The sabot's purpose

is to keep the narrow penetrator centered in the wide gun barrel.



On firing, the propellant casing remains in the chamber, and the expanding

gas pushes the sabot and attached penetrator down the barrel. The sabot is

attached to the penetrator with relatively flimsy plastic, so it falls away

as soon as the round leaves the cannon. The heavy penetrator flies through

the air at high speed toward its target tank. Because of its narrow shape,

the penetrator focuses its full force into a very small area, plowing

straight through heavy armor. As the penetrator enters the tank, heated

fragments of metal fly off in all directions, hitting anybody and anything

inside."



See: http://www.howstuffworks.com/m1-tank3.htm

For an interesting story on the effectiveness of these munitions see:

http://www.softwhale.com/history/hist-abrams.htm



Pete





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