Friday, May 4, 2012

Rods From God

There's an urban legend about a woman killed by a shaft of frozen urine fallen from a plane's leaking toilet.

Then there's the one about pennies dropped from the top of the Empire State Building, passing through pedestrians' skulls like bullets.

Then there's the one about telephone pole-sized tungsten rods dropping from an orbital weapons platform at 36,000 feet per second to impact the earth below with the force of a meteor strike.
Guess which one you won't find on Snopes under "stupid bullsh*t?"

Yes, enormous Swords of Damocles hanging in space are one more reason to lie awake at night, thinking about how much safer we feel thanks to science.

The so-called Rods From God system would have two satellites placed in orbit, one to control communication and targeting, the other containing the rods.

When released, nothing but gravity and a little remote guidance is needed to bring them down on target like the wrath of Zeus.

The brute force of hundred-kilogram rods traveling over 7,000 MPH makes them ideal for penetrating underground bunkers, your mother, and hardened nuclear missile silos.

You know, things you might find in a rogue state, in violation of the Nuclear Non-Proliferation Treaty.
Such treaties don't apply to hypervelocity rods, though they strike with the force of a tactical nuke, they produce no radioactive (and far less political) fallout.

The US Space Command (where we always claimed our Dad worked even before we knew it existed) says they plan to have this capability by 2025.

While on the subject of interesting approaches to weapons of, not exactly, mass destruction; have you heard about "rail-guns"?

A rail-gun, it seems isn't a big cannon that shoots old hardware from the local RR right-of-way.  Instead, it's an electric weapon which uses huge amounts of electric power (around 10 to 60 megajoules) for a few microseconds or so to create an extreme amount of magnetic repulsion between the weapon and its projectile. 

The net result is an extremely motivated projectile, perhaps a few pounds of aluminum (aluminium, for our British cousins) in the form of a gnarly big dart, proceeding targetward at around mach 10 or so.

The extreme acceleration and correspondingly over-the-top velocity mean that the projectile tends to be accompanied by a short column of flaming, overheated air as it pops out for a couple of hundred nautical miles in a few heartbeat's length before annihilating its unfortunate target in a violent outburst of energy caused by the irresistible force running dead-on into the immoveable object.

Perhaps some of this stuff interests me more than it will others because long-long ago I was a gunner in the Navy, and the rail-gun - for now, at any rate, will be a naval weapons system.  Or, it could be land-based. 

Because of its rather huge electrical current needs, a land-based system or one on a large ship, which has its own electrical generation equipment, will be the first uses.  As a shipboard system, it has some advantages which might not be obvious to people who've not been involved in naval gunnery and its logistics.

The projectiles are functional without the two liabilities which most burden navy ships as gun or missile platforms: no explosive propellant needed, and no bursting charges nor explosive warheads to be hauled around.

The rail-gun's projectile is inert, it's just a hunk of metal.  What makes it into a killer and a high-explosive is the kinetic energy imparted by the velocity with which it strikes the target.   If you think getting run into by a 500 grain bullet doing 2000 MPH is bad, and it is, consider the energy involved in stopping that great flaming slug from the rail-gun!

Of course, they're developing a discarding tungsten sabot round and working toward accelerations in the 60000 G range for a system with accuracy within three meters at two hundred nautical miles with a ten shots per minute cycle rate.  With that high a cycle speed it would be usable as an anti-aircraft system as well.

I know their fire-control systems are considerably advanced from the old days when we used vacuum-tubes in our target designation system and in our fire-control radar sets.  But we could only shoot about fifteen miles in those days and accuracy was about ten meters at ten miles, which meant the plane might get by the detonation without much, or any, damage.

So, we had to keep hitting him until he exploded.  Even with a twin mount and fairly rapid cycle rate it could take too long.  Even at mach 1 it doesn't take long to cover ten miles...   Maybe a minute.
Closing straight at you at around eight-hundred knots and flying at wave-top level, a jet fighter is an awesome beast.  You don't get to miss very many times on each run in by an enemy aircraft.

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