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A missile punch at bullet prices page 2
Dahlgren demonstrates electromagnetic rail gun
Date published: 1/17/2007
continued He compared the process to charging up a battery on the flash of a digital camera, then pushing the button and "dumping that charge," producing a magnetic field that drives the metal-cased ordnance instead of gun powder. The projectile fired yesterday weighed only 3.2 kilograms and had no warhead. Future railgun ordnance won't be large and heavy, either, but will deliver the punch of a Tomahawk cruise missile because of the immense speed of the projectile at impact. Garnett compared that force to hitting a target with a Ford Taurus at 380 mph. "It will take out a building," he said. Warheads aren't needed because of the massive force of impact. The range for 5-inch guns now on Navy ships is less than 15 nautical miles, Garnett said. He said the railgun will extend that range to more than 200 nautical miles and strike a target that far away in six minutes. A Tomahawk missile covers that same distance in eight minutes. The Navy isn't estimating a price tag at this point, with actual use still about 13 years away. But it does know it will be a comparatively cheap weapon to use. "A Tomahawk is about a million dollars a shot," McGettigan said. "One of these things is pretty inexpensive compared to that." He said estimates today are that railgun projectiles will cost less than $1,000 each, "but it's going to depend on the electronics." Projectiles will probably eventually have fins for GPS control and navigation. To achieve that kind of control and minimize collateral damage, railgun ordnance will require electronic innards that can survive tremendous stress coming out of the muzzle. "When this thing leaves, it's [under] hundreds of thousands of g 's, and the electronics of today won't survive that," he said. "We need to develop something that will survive that many g 's."
At the peak of its ballistic trajectory, the projectile will reach an altitude of 500,000 feet, or about 95 miles, actually exiting the Earth's atmosphere. The railgun will save precious minutes in providing support for U.S. Army and Marine Corps forces on the ground under fire from the enemy. "The big difference is that with a Tomahawk, planning a mission takes a certain period of time," McGettigan said. "With this, you get GPS coordinates, put that into the system and the response to target is much quicker from call to fire to actual impact." General Atomics, a San Diego defense contractor, was awarded a $10 million contract for the project last spring. The concept was born in the 1970s then promoted when President Ronald Reagan proposed the anti-missile "Star Wars" Strategic Defense Initiative. The SDI railgun was originally intended to use super high-velocity projectiles to shoot down incoming ballistic missiles. To reach MICHAEL ZITZ:
Date published: 1/17/2007
A Former Star Warrior's View
(posted by
Hop
, Sep. 25, 2007 2:41 pm)
As a former "Star Warrior," working on everything from rail guns to e-beams and lasers in the 70s, I can offer this observation: nothing we have been able to make (nuclear excepted) packs more power per unit volume than chemical explosives. Energy on target is not decisive. Momentum on target is, and that's what you get with a heavy HE warhead. Rail guns have a short time-of-flight, but deliver little momentum to the target, which is okay for destroying missles in flight but not standing buildings.
real use
(posted by
terrybrookman
, Sep. 25, 2007 2:41 pm)
The real firing platform will be in orbit and with the speeds you get in a vacuum plus firing into a gravity well you can hit anything on the planet or flying above it. The projectiles could be of any configuration solid with an ablative coating that could reach ground level as iron plasma traveling at two hundred thousand feet per second ro something like a shotgun shell that would burst into a cloud if iron plasma pellets traveling at the same speeds. You could hit a missile in first stage lift,
16 inch nava gun
(posted by
Limey
, Sep. 25, 2007 2:41 pm)
A 3000 pound projectile at muzzle velocity of 2800 fps gives muzzle energy of 495 Megajoules. Problem of solid projectiles is small radius of lethality, a miss at long range is no better than one at short range.
Nitpickin'
(posted by
phantomanalyst
, Sep. 25, 2007 2:41 pm)
Buck Rogers, in the Philip F Nowlan novel, used a rocket
pistol (like a Gyrojet). Using electricity doesn't 'eliminate
the possibility of explosions' just reduce it; if a gun with that
muzzle velocity suffers structural failure on firing, what will
happen will be an explosion. If the power from the pulse
generator is shorted to the ship's structure before firing in
an uncontrolled fashion, BANG. Note there is a problem
also with emitting massive EM bursts if enemies are trying
to locate you.
Questions...
(posted by
geracitano
, Sep. 25, 2007 2:41 pm)
A nautical mile is 6075 feet, whereas a statute mile is 5280 feet. So 200 nautical miles is about 230 miles.
Current 16inch naval guns fire 3000lb shells at 2800fps, which is equivalent to a muzzle velocity of over 1900mph. Wind resistance is going to slow it down from there. But the whole purpose of developing a rail gun is to overcome the velocity limitations of chemical propellant. Which clearly, according to this article, it does, and does well.
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