From: Spike Jones (spike66@ibm.net)
Date: Tue Jan 05 1999 - 23:21:08 MST
> > somebody (?) wrote: Would a chunk
> > of metal (can of ravioli) impacting another, larger, rest mass
> > structure (star destroyer) produce an "explosion" effect, or simply
> > punch an appropriately shaped hole as it passed through? Bill?
depends on the speed of the can.
when the start 2 agreement was signed, we were left with a number of reentry
bodies with no nukes to carry. (thank you george bush). i was on a team
that was tasked to think of alternate applications for these stunningly
expensive devices. we thought of making them into "kinetic kill vehicles"
or very sophisticated very fast moving cannonballs. the notion was to
use them to destroy underground bunkers.
turns out, at very high velocities (higher than about 5 km per second) a
curious phenomenon occurs known as the hydrodynamic impact regime.
above this velocity, the energy released on impact is much larger than
the heat of vaporization of the target, and so it doesnt even matter what
the target is made of, only the speed of sound in that target. as i
understand
it, at the instant of impact, the projectile vaporizes at the speed of sound
in
that projectile, while the target vaporizes at the speed of sound in the
target.
so, above a certain velocity, you dont continue to punch a *deeper* hole,
but only a *wider* hole. which explains why the craters on the moon
are wide shallow things, some big, some small, but none really deep.
so it turns out, even if you can get one accurate enough, a kinetic kill
vehicle is not so great for detroying deeply buried targets, unless you
can get them to follow one after another into the same crater.
a spinoff technology was a project we called spears from space. we derived
some, uh... well, spears, made of tungsten. we had great fun with tungsten
because it is so dense. nothing in one's ordinary experience is like tunsten.
imore than twice as dense as lead, way denser than gold, yet looks like any
gray
metal. if you have a block of it the size of a brick, it takes a real effort
to
hoist the item, and even then it is not advisable for if one were to drop it
upon
ones lower extremities one would surely damage oneself severely. {8-[
the idea was to drop one spear after another into the crater made by
previous impacts, thereby discouraging those who would seek refuge
in deeply buried bunkers. the system was never deployed. {8^D spike
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