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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?
http://agrenville.myminicity.com/
http://agrenville.myminicity.com/ind
http://agrenville.myminicity.com/tra
http://agrenville.myminicity.com/sec
http://agrenville.myminicity.com/env
In Memory of Russ Manduca 7/22/67-1/8/08 and Kristy Kozlowski Braker
10/2/66 - 6/12/10
Certainly there is no hunting like the hunting of man and those who have
hunted armed men long enough and liked it, never really care for anything else
thereafter. ~ Ernest Hemmingway
"I'm a Member of Red Sox Nation"
http://www.youtube.com/watch?v=_6ElEgp62dI
> 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.
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)
> Doc wrote:
Not an expert, here's a rough comparison:
A 5" shell is about 30kg warhead, a 16" Iowa shell is 1225kg. The only weight
I've seen (so far) given for the 32MW railgun is a 20kg dart. So for
ammunition storage and handling it's much closer to the 5" than to a
battleship gun.
The muzzle velocity for the 5" gun is 760 - 800 metres/second,
the 16" Iowa is 760 metres/second. The railgun is reported at
Mach 7, 2300 metres/second.
The railgun round does damage through kinetic energy rather than explosive
force, and since it's three times faster and KE is proportional to velocity
squared, that's roughly nine times as much damage as the 5" shell. While it
can't pack in as much explosive as a HE version of a battleship shell,
whatever you hit is going to have one heck of a hole in it.
That Mach 7 velocity also gives it an effective range of 180km or so with a
flight time of around 80 seconds.
Anyone got more details?
cheers,
I read the article -- the thing I don't understand is that why do people
think this would replace missiles? I can see using this at fairly low ranges,
when
you have a line of sight at the target (and anti-air defence just got a
hell of a lot scarier, if they can get this to work reliably) but, I didn't
think you could shoot over the horizon practically with a railgun, because the
trajectory is so flat.
JGH
> On 12/12/2010 4:31 PM, Doc 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.
http://www.youtube.com/watch?v=_6ElEgp62dI
> _______________________________________________
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http://mail.csua.berkeley.edu:8080/mailman/listinfo/gzg-lOn Mon, Dec 13,
> 2010 at 2:28 PM, Jerry Han <jhan@warpfish.com> wrote:
> I read the article -- the thing I don't understand is that why do
You fire an arcing shot and control the round with GPS signals. Or so the
article states. ;-)
Mk
Dang. Missed that bit. (8-)
That's a hell of a control problem. Whew.
JGH
> On 13/12/2010 10:39 PM, Indy wrote:
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Gzg-l mailing list
Gzg-l@mail.csua.berkeley.edu
http://mail.csua.berkeley.edu:8080/mailman/listinfo/gzg-lThe article I
saw had: 23 pound bullet Mach 8
5500 ft/s (I question this, but it may be based on projectile weight)
(allegedly the final system should be over 5800 m/s, but not sure what
projectile weight) 33 MJ 1.5 million Amperes energy dump took 10 ms adjustable
power levels shipboard defensive deployment est. 2020 to 2025 multiple 2"
thick coaxial cables fed by stacks of refrigerator sized capacitors gun is the
size of a school bus
5 minute charge time (target is 10 shots/min)
Expected impact will be equivalent to Tomhawk allegedly, but much cheaper
Plans to fire at 64 MJ where 200 miles = 6 minutes travel time (Wikipedia
claims 370 km or 200 nm)
Now, assuming they get this right: 1) New fire support ship as the Navy &
Marines were denied that capability when they retired the BBs 2) Outranges
some missiles, might move us back more towards the dueling of ships of the
line with guns 3) Big power requirements, even for big ships, and power
supplies won't like hits 4) Smaller versions might be interesting in armoured
vehicles, as PDS mounts, or as smaller ship main guns 5) Recharge time might
not matter if you can outrange enemy (by an order (or more) of magnitude
potentially) and hit accurately at OTH distances with a round that will do
some serious damage 6) Trajectory may look flat, but shoot up and it will arc
(add GPS guidance and you can drive it to target a bit)
7) Defenses seem to be: Ridiculous armour, amazing PD charges/systems,
or perhaps 'being crazy fast and all ninja!'
So, we've got something that (allegedly) will hit like a Tomahawk, can be
delivered out to 200 nm, 10/second, for a lot less than $1M per pop
(ammo cost, not counting R&D, deployment, or other costs amortized over
lifespan of weapon system).
That sounds quite potent. I'm not sure what the flight time for large scale
anti ship missiles is from launch to a target ship 200 nm away... whether it
is more or less than 6 minutes, I'm not sure. But this seems pretty quick to
me.
> On Mon, Dec 13, 2010 at 8:39 PM, Indy <indy.kochte@gmail.com> wrote:
> [quoted text omitted]
> Jerry wrote:
It's more a complement to missiles than a replacement.
You're not going to hit moving targets at 180km without
fairly amazing aerial/satellite tracking. (At least on
Earth you won't, space is another matter entirely.) The focus seems more on
hitting ground targets such as bunkers from a long way offshore, and doing so
with cheap chunks of metal instead of expensive missiles.
At long range, over 100km? or so, the trajectory should have enough arc to
clear buildings in the way.
cheers,
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Gzg-l@mail.csua.berkeley.edu
http://mail.csua.berkeley.edu:8080/mailman/listinfo/gzg-lHugh, I am not
disagreeing with your general conclusions, but there is a little thing I would
like to correct on your reasoning:
> A 5" shell is about 30kg warhead, a 16" Iowa shell is 1225kg. The
They are talking about 33 MegaJoules, not megawats (I do not think they
mention how much power was necessary to achieve that energy, or how big the
batteries and capacitors were). Â That is the (I assume, muzzle) energy of the
round that was shot. Assuming sea level, and standard (or close to standard)
atmosphere and temperature, Mach 7 is 2380 metres per second. Â
33 megajoules kinetic energy, at 2380 m/s, would imply the projectile
had a mass of almost 12 kg (about 25 lbs). Â
Anyway, it IS an amazing and potentially game-changer achievement. There
are not many man-made things than have reached that speed.
 And it is a step forward towards Gauss Rifles;)  Just my 2 cents, Â
Not sure that this is completely clear. May not have/need a guided
projectile. If the GPS unit can be used to locate the target and the firer,
computer systems should do a pretty good job of being able to set the power,
direction and trajectory needed to score the hit. If the shell is sent to the
right place, it likely hits.
Of course you're going to have issues like wind, accuracy of the targeting
system, etc., but the shell shouldn't need internal guidance.
:)
J
On Tue, Dec 14, 2010 at 3:20 AM, Richard Bell <rlbell.nsuid@gmail.com> wrote:
> On Mon, Dec 13, 2010 at 8:39 PM, Indy <indy.kochte@gmail.com> wrote: