Taking Ballistics by Storm

"When you first hear of a gun without any moving mechanical parts, you tend to laugh. I know I had to withhold my giggles," said physicist Adam Drobot of Science Applications International Corporation (SAIC), a private, multi-billion dollar company that evaluates new technologies on behalf of the US military. "But once you see the videotape of this test-firing," he added, "the giggle factor goes away."

The gun in question is something that even its inventor says "comes out of left field". Termed 'Metal Storm,' this new weapon has no hammer, no trigger, no breech block and no shell casings to eject. Equally unusual, it fires one million rounds per minute; in comparison, the fastest weapons -- Gatling guns -- only fire 6,000 rounds per minute.

Metal Storm's origins are equally unusual. It was invented by former grocery retailer Mike O'Dwyer, a lone Australian tinkerer with no formal education in ballistics or engineering. His previous patents are for devices such as air-cooled sneakers. ("They pump air through as you jog," he explained.)

After 15 years of trial and error in his tropical Queensland home, O'Dwyer came up with a gun prototype that recently fired 180 rounds of 9mm bullets in 1/100 of a second during a demonstration before military officials in Adelaide. Metal Storm's bullets leave its barrel so quickly that they are only nanoseconds apart -- when one bullet is flying through the air, the next is just fourteen inches behind. For current machine guns, the gap between bullets is 100 feet.

Major David Goyne, a weapons specialist at Australian Defence Headquarters, describes its potential as "revolutionary." He said, "It could replace our existing technology on the battlefield." The gun is ideal for close-in, tight situations where soldiers need to fire large amounts of metal into the air quickly and accurately, such as defending ships against incoming missiles. Goyne commented that it could also be used to clear land mines in open areas like Kuwait's deserts; a helicopter using the gun could hover above the sands and clear a minefield by spraying it from a distance, exploding the mines harmlessly.

The gun works by using a combination of specially-designed bullets and an electronic firing mechanism. O'Dwyer describes it as "a barrel tube with an electrical wire attached." Jacketless bullets are lined up inside, nose to tail, separated from each other by a layer of propellent.

When an electrical current makes its way down the strip, the bullets are set off one by one. To stop them from going off simultaneously, they are designed so that the high pressure caused by the firing of the first projectile makes the nose of the next one in line swell against the walls, temporarily sealing off the rest of the barrel. (In ballistics terms, the nose of the second bullet effectively acts as a breech block to prevent an uncontrolled sympathetic ignition.) After the first bullet exits, the pressure is gone, the nose of the second one loosens up, and it can be fired. This process continues for each successive bullet. Other than the projectiles themselves, there are no moving parts.

To get even more firepower, several loaded barrels can be set up side by side.

Variations of electrically-fired weapons had been tried before, most recently when Sandia Laboratories developed an electromagnetic coil gun designed to send 450 kilogram satellites into orbit (Scientific American, April 1990, page 20). However, there are a number of differences between the two approaches, says Vinod Puri, senior research scientist with the Australian Defence Science and Technology Organisation: "The electromagnetic coil gun demands lots of energy, achieves high velocities, and sends large objects great distances. In contrast, Metal Storm requires less energy, works at lower velocities, uses normal gun propellent, and sends out more, smaller projectiles per minute for shorter distances."

O'Dwyer points out another feature of guns like Metal Storm: because they are all electronic, they offer a good opportunity for electronic safeguards. To operate the weapon, a person would have to punch in a PIN number on a keyboard, much like an automatic teller machine. Because Metal Storm has no mechanical parts, if an unauthorized user tried to bypass the gun's security system by disabling the electronics, the gun simply couldn't fire.

There are many non-military uses for a device with a built-in security feature that can repeatedly fire small bits of metal quickly and accurately, says Drobot. He expects it could replace the nail guns used by carpenters and roofers, and may find a use in riveting and other industrial applications.

The technology still needs fine-tuning, says Goyne. It fires a relatively small caliber, for example. But physicists such as Puri say its basic design is "very solid."

The weapon is being promoted by the Australian Trade Commission, and attracted attention in Australia and Britain. General Dynamics tested it here and SAIC contracted to help develop it further. Fenner Milton, the person in charge of weapons acquistion for the US Army, attended a test firing of a Metal Storm prototype in Australia. He said he was impressed, and added "In my opinion, Metal Storm represents a truly innovative approach to lethality, that if further developed has great potential for defensive weapon systems that can take advantage of its extraordinarily high burst rate of fire."

What seems to surprise most experts about the technology is its source. "It sometimes takes someone who isn't very conventional to come up with new ideas. My amazement is at the process - O'Dwyer didn't blow up a barrel or kill himself while making it."

Dan Drollette
Scientific American

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