scott nous apporta ses lumieres en ce 2007/10/25 03:11:
>> Well, in an atmosphere, it would be like being hit by an explosion, as 
>> you pile up all the air in front of it.
> 
> Wouldn't something going that fast vaporize immediately when it hit the 
> air going that fast?  Doesn't stuff that going only a fraction of that 
> speed burn up in the outer atmosphere?
> 
>> Plus, don't forget all that nice gamma-burst radiation. (The railguns 
>> in the story actually had to fire for a few thousand rounds to punch a 
>> hole in the atmosphere so the needles wouldn't just vaporize.)
> 
> Ah yes, ok :-)
> 
>>> Well... technically a railgun (not to be confused with a coilgun) 
>>> fires projectiles using electrical propolsion. There's nothing in the 
>>> definition about how fast. ;-)
>>
>> True. But to get the electrical propultion to work, the projectile 
>> needs to be pretty small, which means it needs to go pretty fast. 
>> Otherwise it's more of a thrower than a firearm. :-)
> 
> In one of our lectures at university the dude had this rail-gun.  It was 
> about 2 metres long and plugged into the 420V 3-phase power supply.  He 
> loaded it with a brass (I think) solid lump of metal that was in a 
> pointy bullet shape.  It wasn't small, about 10cm diameter and 30cm 
> long.  When he flicked the switch it punched through (and got stuck in) 
> a big bit of wood just off the end of the bench he was using.  Rig up 10 
> or 20 metres of that baby and it would be interesting :-)
> 
> 
The bullet would have been hypersonic, not relativistic! Anyway, beter protect 
your ears when it fires... and don't stand anywhere close to that thing!

-- 
Alain
-------------------------------------------------
Lutheran: If shit happens, don't talk about it.

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