Re: [GZG] Railguns

On Sun, Dec 12, 2010 at 2:31 PM, Doc <docagren@aol.com> wrote:
>
http://www.foxnews.com/scitech/2010/12/10/navy-railgun-shoots-bullets-el
ectromagnet/
> It seems that the Railgun is 1 step closer to working for really.
>
> So can 1 of you weapon expert give me an idea of the damage this test
shot
> does compare to a 5" or 16" shell?
>

I do not have the muzzle energy of a 16" gun at my fingertips, but the
NATO L7 105mm/51 tank gun used on the early M1's had a muzzle energy
of 9 megajoules.  The WWII german 12.8 cm antitank gun had a muzzle
energy of 12 megajoules.  The railgun spits projectiles at three times
the muzzle energy of a high velocity 5" gun.

While the railgun does not have explosive propellants, any energy
accumulator that can store the required energy and discharge it at a
rate high enough to impart a muzzle energy of 33 megajoules will not
take kindly to physical insults.  Of more interest is how the rail gun
substitutes fuel for gun propellant through three energy conversions:
fuel heat to mechanical power, mechanical power to electrical power,
and electrical power to railgun propulsion.  Mechanical to electrical
conversion is over 90% efficient, but the heat to mechanical
conversion is only about 40%.  I cannot find a quote for the
efficiency of railgun propulsion, but it is safe to say that it is
less than 100%.  Unless the energy densities are comparable, trading
fuel for gun propellant may be a problem.  For nuclear powered
vessels, this is a non-issue; although, it will need a big enoughg
electrical supply (the CVNX, with its electromagnetic catapults, is a
natural choice for mounting rail guns)
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