Wednesday, January 30, 2008


Apparently the US Navy is starting down the path to Galactic Civilizations 2 Black Hole Gun. Heh. Seriously though the USN announced yesterday that they plan to test fire an electromagnetic rail gun at 10 Mega Joules. That is serious sci-fi stuff. Much realer than the little orange men nut jobs all over the world discovered last week too.

A rail gun is basically a way of propelling something really really fast. So fast that you could technically just have a solid ball or rod and still do tremendous damage to your target just from going fast. Think of car crashes for an idea. Neither car (presumably) has explosive warheads but when they crash together a lot of damage is done just because they are moving.

For given values of kinetic energy it’s probably more effective to just have solid masses instead of actual payloads on the projectile although I’m not familiar enough with the math to know where the sweet spot is. I would assume that the lower the power used to launch the projectile the more likely it would be to have an explosive warhead on them. At some launching power it would no longer make any sense since more damage would be done by the kinetic impact than by the payload.

OK major nerd mode there.

Anyway, rail guns are cool ideas and can be used for lots more than throwing bullets. Massive rail guns could easily accelerate something to orbit and might be a highly effective way to send cargos (if maybe not people because the acceleration stresses would be really high) to space. This summer I rode a roller coaster that used magnets to accelerate the cars instead of using a chain and a gravity drop for the initial boost. Same thing as this gun on a different scale.

Anyway, check out this fun little animation of how rail guns work plus get an intro to the physics over on

1 comment:

John O said...

Now they just need to build a railgun that runs up the side of a tall mountain and exits facing west at something higher than a 45 degree angle. You get to exchange all the fuel to get a rocket to 20,000 feet at > mach 1 speed for a reusable electrical system and a really big power bill.

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