Michael Pollak:
> And isn't the reason that DU munitions are so effective at
> penetrating armor (which is why the military is so loathe to give
> them up) because they ignite on contact -- thereby turning most of
> their mass into just this kind of dust?
almost.
typically, DU ammo is fired at such high velocities that upon impact
with armor, both the projectile and the armor cladding become quite
hot and almost fluid-like. the DU projectiles are believed to have a
self-sharpening caharacteristic, in that as they bore through the
pseudo-liquid armor, they shed (shear) material off themselves in just
such a way as to maintain a sharp tip in front. this aids in further
penetration. tests apprently showed a 10-20% improvement over tungsten
ammo, which was the predecessor in the hardened ammo repertoire.
by the time the DU projectile bores through the armor plating, a
significant fraction (20 - 70%% or higher) of its mass can pop out the
other side in the form of dust/vapor which is indeed highly
combustible/exposive in air.
the touted advantages of DU ammo by the military thus stem from three
factors: the high mass density of DU (see physics links below) along
with self-sharpening allows for higher penetration depths for a given
firing speed. it has also been pointed out that these high density
projectiles, due to their typical construction as long thin arrow
shaped rods that gives them decreased air drag at a given firing
speed, allow troops to fire from much farther away than with typical
ammo. you can then understand the US mil's fondness for these weapons
in terms of potential reduction in "allied" troop losses due to
remaining large distance from the "enemy".
[ incidentally, uranium as projectile and uranium as nuclear material
is not an accident. high density comes from such a high mass
concentration in nuclear core. this also puts it near the nuclear
stability limit, such that smacking it with an energetic neutron
produces high energy fragments PLUS more neutrons, and hence chain
reaction. ]
some URL's i've collected:
1.) one stop shopping for anything you want to know about the
radiological properties of uranium and relatives:
http://www.antenna.nl/wise/uranium/index.html
http://www.antenna.nl/wise/uranium/rup.html
note in particular that depleted uranium actually increases in
radioactivity over time, due to the complex web of nuclear reactions
which can take place.
2.) a very interesting paper on DU:
http://arxiv.org/abs/physics/0301059
which argues that these are "next-generation" nuclear weapons. the
author makes a case that the relative advantages of DU over tungsten
clad ammo in terms of penetration capability are not significant
enough to explain US mil's fondness for these weapons. i'll probably
write a summary of this paper at some point.
3.) re/ Eublides post yesterday on grid parallel computers, there is
a large effort to simulate these high-velocity impacts of DU ammo
using parallel systems:
http://www.hpcmo.hpc.mil/Htdocs/UGC/UGC02/paper/tom_kendall_paper.pdf
http://www.sv.vt.edu/research/batra-stevens/pent.html
http://scholar.lib.vt.edu/theses/available/etd-3753128097370/
one example of the unity of weapons simulation and computational
systems development. there is some debate over the actual
mechanisms for self-sharpening, hence the effort at using parallel
computer systems.
4.) physics of DU penetration abilities (and dust generation):
http://arxiv.org/abs/physics/0305120
http://www.ead.anl.gov/pub/doc/Depleted-Uranium.pdf (page 2)
http://www.army-technology.com/contractors/ammunition/apfsds.htm
http://authors.elsevier.com/SampleCopy/700/S0734-743X(99)00032-9
http://www.journal.dnd.ca/engraph/Vol4/no1/pdf/v4n1-p41-46_e.pdf
5.) other suspected uses of DU clad weapons:
http://www.eoslifework.co.uk/pdfs/DU2102A3a.pdf
http://www.eoslifework.co.uk/pdfs/DU2102A3b.pdf
valuable in concert with reference in 2.)
les schaffer
