For Love of a Gun
The tumultuous history of electromagnetic launch
One day in 1977, researchers at Australian National University were putting the finishing touches on an experiment that they hoped would cap nearly a decade’s worth of groundbreaking research on electromagnetic guns. Tantalized by the prospect of unleashing the pure power of electromagnetism to accelerate projectiles at rates never before achieved, countless researchers had been pursuing the technology since the turn of the century. But without much success.
An engineer loaded a 3-gram Lexan cube into the 5-'meter-long barrel of a contraption that looked like a cross between a cannon and a particle accelerator. He threw the switch on a huge 550-megajoule generator and then took a few steps back as the generator hummed up to speed over several minutes, its giant flywheel rotors spinning and singing as they stored kinetic energy. He threw another switch, releasing the generator’s charge in a stupendous 2-million-ampere pulse [see photo, "Ready to Launch," below].
The Lexan cube flew from the barrel and across the room “like a meteorite,” the railgun’s designer, Richard Marshall, later recalled. Accelerated to half a million g’s, it had reached an astounding 5.9 kilometers per second. At such a speed, if it could be sustained, a trip from London to Los Angeles would take just 25 minutes.
Ready to Launch: Richard Parkes (left) and Scott Rashleigh at Australian National University make last-minute tweaks to a railgun that set the speed record for such machines in 1977.Photo: Australian News and Information Bureau
Marshall’s device had set a world record for electromagnetic guns, but what the inventive New Zealander couldn’t have imagined then is that his record would still stand today, 30 years later. It hasn’t been for lack of trying: he and a small cadre of true believers have spent much of the past three decades struggling to advance this frustratingly elusive technology, for use as an advanced weapon and even to launch satellites into orbit. Along the way, they have encountered nearly every pitfall that can beset the development of a promising new military technology: poorly conceived projects and ill-informed politicians, overreaching colleagues and overinflated results, and funding booms that precipitously went bust. Compared with the politicking and turf battles, the huge technical hurdles that Marshall and other researchers faced seemed quite tractable. Those challenges, at least, were subject to the laws of physics and the craft of engineering.
Most of all, the recent history of railgun research is a cautionary tale about military R&D. It’s an enterprise where the best technology doesn’t always win, and even when it does, it may very well have cost far more to field than it should have [see timeline, "Selected Events in the Colorful History of Electromagnetic Guns"].
This particular story may end in success. The persistence of electromagnetic-gun researchers seems to be paying off at last. In recent years, interest in electromagnetic guns has soared, with the United States, China, Russia, and 13 other countries now supporting robust R&D programs. The U.S. Army and Navy envision EM guns as a key component for the next generation of all-electric vehicles. The Chinese, meanwhile, have set up no fewer than 22 research institutes studying various aspects of electromagnetic launch (EML), including an intriguing use in tank armor. If these efforts pan out, it will be a remarkable comeback for a technology that only a few years ago looked moribund. Having watched their prospects wax and wane and wax again, EM gun researchers may finally have reason to hope.
You have to be an optimist to work in this field, given all the tribulations you’ll inevitably encounter, day after day, year after year. If the EM gun community has an Optimist in Chief, it would be Harry D. Fair, director of the Institute for Advanced Technology at the University of Texas, Austin [see photo, "True Believer,"at top of page].
Fair began working on electromagnetic launch in the mid-1970s. Back then he led a team of physicists at Picatinny Arsenal, the U.S. Army outpost in northwestern New Jersey responsible for building better guns. “We used to get together at the Mt. Hope Inn and talk over Reuben sandwiches,” he recalls. “We came to the conclusion that chemical propulsion had reached its asymptote” for both guns and rockets. What the Army needed was a radically new propulsion technology.
The key word here is “radical.” “We looked at catapults, storing energy in rubber bands. We called our discussions the ‘Nutty Ideas’ project,” Fair says, with a laugh. Eventually, two related technologies stood out, both based on electromagnetism: railguns and coilguns.
The railgun [top] gets its name from its two parallel conducting rails; dc current travels up one rail and down the other, creating an intense magnetic field inside the gun’s barrel and propelling the armature and projectile. The coilgun [bottom] consists of one or more coils of wire, each of which is powered on and off in succession, creating a magnetic field that pushes or pulls the projectile to the next coil. The pictograms show proposed uses for electric guns.
Illustration: Bryan Christie Design
A railgun has few parts: a pair of parallel conducting rails inside a barrel, an armature that rides the rails, and a projectile in front of the armature [see diagram, "Gun Control," above]. A jolt of dc current applied to one rail will travel up it, across the armature, and down its mate, completing a circuit and filling the gun’s barrel with an intense magnetic field. The barrel contains the pressure of this field, known as the Lorentz force, and so the only part that can yield to the pressure is the movable armature. The armature shoots out of the barrel, along with the projectile, at speeds as high as tens or even hundreds of kilometers per second—at least in theory. The most powerful conventional gun, by contrast, maxes out at about 2 km/s (about 4500 miles per hour).
The coilgun takes advantage of the fact that an electrical current flowing through a coil of wire creates a magnetic field. The barrel of a coilgun consists of one or more such coils, with a projectile in the center. The coils are powered on and off in succession, and each coil creates its own magnetic field; the field either pushes or pulls the projectile to the next coil. Timing is everything: if the coil energizes too soon or too late, it slows the projectile instead of accelerating it. A maglev train is a very long and very slow variation of a coilgun, although a coilgun requires a pulsed power source, whereas a maglev does not. One maglev design calls for jet engines instead of magnetic propulsion.
These ideas have been around since at least 1901, when a crowd gathered at the University of Oslo to witness the first public firing of a 6.5-centimeter-caliber, 4-meter-long coilgun, built by Kristian Birkeland. The test was suggestive of tribulations to come: a short circuit caused the gun to self-destruct in a burst of sparks and flame, and Birkeland soon turned his attention to fertilizer production.
During World War II the Germans and Japanese toyed with electromagnetic guns, with limited success. The German team built and tested the first large-scale railgun, which accelerated a 10-gram projectile to 1.08 km/s; however, the projectile melted in the process. The Japanese opted to develop a coilgun; though the plan was to project a 2-kilogram slug to a speed of 2 km/s, the machine achieved only 335 meters per second.
After the war, UK researchers tried to improve on the German railgun, while U.S. researchers investigated coilguns. The U.S. machine’s peak performance was to launch an 86-gram projectile at a speed of only about 200 m/s—even less than the Japanese had managed years earlier. At the 1957 Hypervelocity Impact Symposium, U.S. Air Force scientists bluntly concluded, “It is not likely that electromagnetic gun techniques will be successful in the near future.”
Selected Events in the Colorful History of Electromagnetic Guns
Professor Charles G. Page of Columbian College (now The George Washington University), in Washington, D.C., publishes a paper in the American Journal of Science and Arts on how to build a coilgun, the first known description of such a device.
Public demonstration of Kristian Birkeland’s railgun at Norway's University of Oslo results in an explosion that destroys the apparatus.
World War II:
Germany conducts research on railguns; Japanese study coilguns.
UK follows up German work on railguns; United States experiments with coilguns. Neither effort meets with much success, leading a U.S. Air Force researcher in May 1957 to conclude, “It is not likely that electromagnetic gun techniques will be successful in the near future for the attainment of hypervelocity.” Nearly all funding for EM guns ceases everywhere.
At Australian National University, Richard Marshall’s railgun sets the world EM gun speed record of 5.9 kilometers per second. MIT professor Henry Kolm successfully demonstrates a coilgun called the Mass Driver I, part of a NASA-funded research program on colonizing space. Later that year, both ANU and NASA decide to cancel EM gun funding.
In December, Harry Fair, a solid-state physicist, wins “peanuts” from the U.S. Army to fund EM gun research.
IEEE holds its first Electromagnetic Launch Symposium, organized by Fair.
Fair joins the Defense Advanced Research Projects Agency (DARPA) and receives funding for research in tactical EM gun weapons. Wang Ying of China’s Ordnance Engineering College reads the proceedings of the 1980 IEEE EML Symposium, gets intrigued, and begins promoting EM gun research.
Strategic Defense Initiative Office supports EM gun research as part of a much bigger effort under the “Star Wars” program, to build defenses against intercontinental ballistic missiles.
SDIO slashes EM gun research, backs rocket-powered Brilliant Pebbles.
Study by the U.S. Army’s William C. McCorkle persuades DARPA and the U.S. Army to slash remaining EM gun research.
Fair leaves DARPA, founds the Institute for Advanced Research at the University of Texas at Austin, keeping a remnant of EM gun research alive.
Wang Ying brings Richard Marshall to China to boost EM gun research.
Renewed U.S. military interest in EM guns leads to big funding boost; in China, 22 military and academic organizations pursue research. Thirteenth IEEE International EML Symposium in May 2006 draws participants from 16 countries.
None of that history deterred Fair and friends at the Picatinny Arsenal. They were tantalized by the possibility of using electromagnetic guns as an extremely cheap means of launching materials into space. To boost something just to low-Earth orbit by standard propulsion today costs upward of US $20 000 per kilogram. Their back-of-the-envelope calculations, by contrast, put the cost of EML at an astonishing $1 per kilogram. Even accounting for inefficiencies in the equipment, EM launches would be cheaper than chemical rockets by a factor of thousands.
Fair’s office shelves are still crowded with books about space flight— The High Frontier: Human Colonies in Space, by Gerard K. O’Neill, Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets, by John S. Lewis, to name a couple. But mining the sky had to wait, for even researchers with giant ambitions must go where the money is. And for nearly the entire history of EML, that has meant building systems that break things and kill people.
Fair’s ideas about EML soon drew the attention of military researchers in Washington, D.C. In December 1978, the Defense Department invited him to brief a gathering of top U.S. intelligence and military leaders. Renaming his “Nutty Ideas” project the “National Advisory Panel on Electromagnetic Propulsion,” he told the attendees of EML’s enormous promise for artillery, aircraft launchers, missile defense, fusion energy—and, of course, space launch.
Fair’s pitch succeeded—sort of. Over the next two years, he was able to fund EML research with, he says, “peanuts—$100K or two.” He distributed the money among the Francis Bitter National Magnet Laboratory (at MIT), Lawrence Livermore National Laboratory, Westinghouse R&D Center, and his own Picatinny Arsenal.
More significantly, he organized (under the auspices of the IEEE) the first of what would become biennial symposia on electromagnetic launch. Over the years, papers delivered at the symposia not only helped move the field forward but also sparked interest in far-flung parts of the globe. “This body of research is what the Chinese and all new folks to the field now use as the basic resource,” says Fair.
At least one project Fair funded had a checkered past. In the early 1970s, Princeton University physics professor Gerard K. O’Neill had gotten enthusiastic about EML. NASA’s Apollo missions were still in full swing, and O’Neill dreamed of building entire cities in orbit. In the August 1974 issue of Physics Today he described floating colonies built of cylinders 6 km wide and 26 km long, and inside of them, picturesque towns with meadows, lakes, sunshine, and even clouds.
Rather than rocketing construction materials into space, he proposed mining lunar rock and then shipping it to an orbiting manufacturing plant. The rock would be moved around by a solar-powered EM launcher—much cheaper than shipping rocket fuel to the moon, he reasoned. Best of all, O’Neill concluded, rather dubiously, these colonies could be created “with existing technology.”
Someone in NASA apparently agreed, because in 1976 the space agency awarded a $50 000 contract to O’Neill and MIT professor Henry Kolm, part of which they used to build a coilgun. Called the Mass Driver I, the 8-meter-long device had its public debut at Princeton, in the lobby of Chadwin Hall, where a conference on space colonies was taking place. A student fished a copper-coil-wrapped bucket—the gun’s projectile—out of a tub of liquid nitrogen, slid it into the barrel, and bang! The crowd erupted in applause as the bucket appeared instantaneously, or so it seemed, at the far end of the gun, colliding with a thud into a padded barrier that kept it from flying the length of the lobby. Kolm estimated the bucket reached a peak speed of 63 m/s. Though the performance was many orders of magnitude below the theoretical upper limit for EML, the experiment was declared a success.
To build Mass Driver II would require more funding, but before NASA could approve it, Wisconsin senator William Proxmire got wind of O’Neill’s space colonies idea. Famed for his “Golden Fleece” awards for government spending he deemed wasteful, Proxmire went on television to proclaim “not another penny for this nutty fantasy.” NASA quickly pulled the plug on all its space colonies projects, including the Mass Driver.
Fair, though, believed the project was worth continuing, and in 1979 he contacted O’Neill and Kolm and said he’d fund their work.
Then Fair came across Richard Marshall. Shortly after his record-setting railgun test in Australia, Marshall, too, had lost his funding. He left the university, moved to the United States, and got a job with Westinghouse in Pittsburgh, where Fair found him in 1979.
Fair, Marshall, Kolm, and their associates now had to confront the enormous technical problems that electromagnetic guns pose. First and foremost is the power supply. Your garden-variety diesel generator won’t work. All railguns and coilguns require a power source that can generate, store, and then emit an enormous burst of current—anywhere from 500 000 to many millions of amperes in a few milliseconds. Marshall had used a homopolar generator, so named because its magnetic field has the same polarity at every point. Just like any generator, it converts rotational mechanical energy into electrical energy. But instead of continuously converting the kinetic energy into electrical energy, the homopolar generator’s rotors store the energy up and then release it in a several-millisecond pulse. Another early railgun experiment called for hooking together thousands of lead-acid car batteries to supply the requisite juice.
Dumping that much current so quickly raises other problems. To begin with, you need a very-large-diameter cable to deliver so much current—anything smaller would melt. The switch, too, has to be specially designed to prevent a massive arc that would otherwise destroy the switch the instant it was thrown. And in the case of a coilgun, where you’re switching the coils on and off in rapid succession, it’s easy to mistime the switching, which in turn can make the projectile wobble. Too much wobble and it won’t leave the barrel at anything close to the target velocity and may also collide with and damage the barrel.
Needless to say, railguns also have a tendency to self-destruct. The high-velocity projectile and armature gouge the rails, and the magnetic fields put a tremendous strain on the rails as they try to force themselves apart. Researchers have considered using superconducting magnets to generate the strong fields needed, but existing superconductors are too brittle and can’t withstand large, rapid changes in their magnetic fields.
Even the projectiles are a subject of intense inquiry. They leave the barrel at such high velocity that when they hit the air, they tend to flatten, burn up, or shatter. That’s why Marshall and others used small, nonconducting pieces of plastic. But for real-world uses, you’d like some way of guiding the projectile to its final destination, tens or hundreds of kilometers away. To send a satellite into space, for instance, you’d equip the payload with some sort of second-stage rocket to insert it into the proper orbit once the payload left the atmosphere. But the conventional electronics of the 1970s couldn’t survive the massive acceleration that an electromagnetic gun produces.
In 1981, Fair joined the Defense Advanced Research Projects Agency, or DARPA, and organized a joint program with the Army, whose goal was to develop a large-caliber EM gun system within 10 years. Interest in the technology was building, but the program was still relatively small by DOD standards. By 1983, Fair’s expected funding was slated to reach only $1.4 million.
Then, on the evening of 23 March 1983, President Ronald Reagan announced a crash program to build defenses against Soviet intercontinental ballistic missiles. Fair and his team were all for Reagan’s initiative—which the press had quickly and derisively dubbed “Star Wars”—but they were dubious about the space-based laser weapons being touted. Fair believed using railguns to launch simple kinetic projectiles, which destroy targets by the sheer force of their impact, would be much better suited for knocking down missiles.
That summer, a study group reviewed the options for missile defense, and in the fall, the Pentagon formed the Strategic Defense Initiative Office (SDIO) to oversee the $1.6-billion-a-year program. Fair was asked to manage its EML component. It was a tempting offer: he would get to allocate $20 million a year to the projects of his choice, but he also worried about working in such a politically charged environment. He chose to stay at DARPA, and Roger X. Lenard, a missile defense analyst and former fighter pilot with the Air Force, became head of SDIO’s EML program instead.
Lenard, too, was a space enthusiast, and he immediately funded an Air Force study of EM guns to launch missile defense systems into orbit, each of them weighing possibly hundreds of metric tons. But the heaviest projectiles that had been test-fired up to then weighed only a few kilograms. Not surprisingly, this challenge proved impossible, and so Lenard shifted the focus to EM guns for hurling projectiles at incoming missiles.
This goal was reasonable, but as Fair and others later charged, the work emphasized hardware demonstrations to the detriment of test and analysis. In an interview with IEEE Spectrum last spring, Lenard said he felt pressured to demonstrate something dramatic because his program was constantly overshadowed by SDIO efforts on directed-energy technologies such as lasers.
One project in particular threatened to steal Lenard’s thunder: at Lawrence Livermore, physicists Lowell Wood and Rod Hyde were leading a program to build a nuclear-pumped X-ray laser. Upon detection of a missile launch, the orbiting system would detonate a nuclear warhead, harnessing the blast to simultaneously power thousands of missile-destroying lasers. News stories at the time quoted Wood as claiming that these lasers could focus so much energy so tightly that just one shuttle launch could put enough of them into orbit to take out the entire Soviet ICBM arsenal.
“The first liar always sets the rules of the game,” is how Lenard ruefully recalls Wood’s boast. He stops short of explicitly calling Wood a liar but does say Wood was “wrong on many implementations of technology.” Lenard recalls one meeting where he pointed out significant problems with Wood’s analysis, but Wood refused to concede any of his points. Wood’s mentor, Edward Teller, was there, and as Lenard recalls, Teller finally snapped, “Lowell, why don’t you shut up and listen to the man? You might learn something.” (Wood and Hyde declined repeated requests to be interviewed for this article.)
In 1985, fabulous-sounding results materialized under Lenard’s program. Railgun teams at Westinghouse and Vought Corp. (now Vought Aircraft Industries, in Dallas) each reported projectile velocities of 5.9 km/s, matching Marshall’s 1977 record. Then a Lawrence Livermore team set up a railgun in Ancho Canyon, N.M., complete with an explosive flux generator, which operates much like a regular generator, except that the motive force is an explosion instead of a drive shaft. The machines generate very high current and voltage simultaneously. The Ancho Canyon railgun reportedly clocked in at 10 km/s—fast enough to launch a projectile from one continent to another or even into low-Earth orbit. Later that year, Maynard Cowan at Sandia National Laboratories claimed a coilgun velocity of 15 km/s.
But the numbers turned out to be grossly exaggerated. When Marshall asked Cowan how he had measured his projectile’s speed, for instance, Cowan said the result had been estimated by a computer. “There’s no substitute for measurement,” Marshall recalls telling Cowan. The Lawrence Livermore results, too, had been calculated instead of measured directly. Marshall, Fair, and others thus put little stock in the claims.
Lenard contends that the tests’ high electromagnetic pulses made measurements impossible. Later, in 1986, they figured out how to measure the velocity—by photographing the projectile as it emerged from the muzzle, among other things. And when they reran the experiments, none of the new guns could equal Marshall’s record from 1977. The projectiles weren’t even solid when they exited the guns, and much of the energy the researchers had thought went into velocity had in fact been released as muzzle flash. Worse, the plasmas generated in the gun barrels corroded everything they touched, projectiles gouged the rails, and the extreme magnetic fields warped the rails. The researchers were constantly rebuilding their guns, usually after just one shot.
Lenard’s researchers made better progress on guided kinetic projectiles that could be fired from an EM gun, or for that matter, from any gun or fast-burn rocket. The projectiles were dubbed “smart rocks” because their airfoils, coupled with homing electronics, allowed them to be steered in midflight. They included the D-2, designed for launching at incoming warheads within the atmosphere, and LEAP (Lightweight ExoAtmospheric Projectile), to be shot from orbiting battle stations.
By 1987, meanwhile, SDIO managers had redirected the program away from laser weapons. Wood’s nuclear X-ray laser turned out to be vaporware—literally. In two underground nuclear tests, sensors meant to measure the lasing effect were vaporized. Later analyses showed that mirrors installed to protect the sensors from radiation had been the primary source of the lasing Wood’s team detected. After an investigation by the General Accounting Office, Representative George Brown, the ranking Democrat on the House Committee on Science, announced that Wood’s claims about the X-ray laser had been “politically motivated exaggerations aimed at distorting national policy and funding decisions.”
By the end of that year, it looked like the main contender for Star Wars would be smart rocks—projectiles based on the D-2 or LEAP and launched by rocket or EM gun. Lenard figured he had won.
He was wrong. Though their X-ray laser had flopped, Wood and Hyde soon returned with a new missile defense scheme, which they called “Brilliant Pebbles.” The idea was to orbit thousands of tiny rockets packed with electronics, along with thousands of space-based sensors. If the sensors detected anything not cleared for space travel, the nearest Pebble would smash into it.
“Lowell Wood is a brilliant salesman,” concedes Lenard. “He and I went toe-to-toe” on Brilliant Pebbles, he added, and Lenard lost. According to news accounts at the time, Teller, a personal friend of Reagan’s, lobbied hard for the project, and in July 1988 Reagan agreed to back Brilliant Pebbles. In a report to Congress, the head of SDIO said that the space-based network could be ready in five years and cost less than $25 billion.
Funding for Lenard’s D-2 and LEAP programs, meanwhile, was eliminated. Sometime later, Navy researchers resurrected LEAP and combined it with its existing Standard Missile technology to create a new version of the Aegis Ballistic Missile Defense System, for defeating short- to intermediate-range missiles.
But the EM gun community didn’t lose out entirely under Brilliant Pebbles: in 1988 and 1989 SDIO funded a $3 million study to launch Pebble components into space using EM guns as well as light-gas guns, which use hydrogen or helium to propel projectiles to hypervelocities. The proposal never made it past the paper-study phase, though. (Brilliant Pebbles was quietly canceled after Bill Clinton became president in 1993.)
Meanwhile, a strong critic of electromagnetic launch had emerged. A review panel was set up to investigate the status of Fair’s DARPA–Army program, which in contrast to the SDIO efforts, was focused on building compact, lower-velocity EM guns for the battlefield. William C. McCorkle Jr., technical director of the Army Missile Command, was on the panel, and he didn’t like what he saw. McCorkle found many technical quibbles with the research, but his main beef was that after five years and half a billion dollars, no gun had yet bested Marshall’s 1977 record. It was time to pull the plug, he said, on “electric gun fraud.”
McCorkle swayed the panel: in 1990 SDIO terminated its EML programs, two years later DARPA followed suit, and in 1994 the Army drastically cut its EML support to about $4 million a year. Projects were abruptly halted midway through, experiments were canceled, and researchers fled the field in droves.
As funding prospects waned, Harry Fair decided to leave DARPA and move to the University of Texas at Austin. There, he formed the Institute for Advanced Technology and kept a remnant of EML work going. Marshall and other zealous advocates took refuge at IAT, and together, on a shoestring budget of $1 million per year, they set about trying to convince the Army that McCorkle was wrong.
For McCorkle continued to attack even the trickle of electric gun funding at IAT. In a letter to Fair, he charged that “EM guns are far from matching or even approaching conventional gun performance in the most distant foreseeable future” [emphasis in original]. Another IAT researcher recalls that in meetings McCorkle would pull out a calculator, ostensibly to produce numbers that proved EML’s inefficacy; but those numbers, the researcher contends, were “by and large, quite incorrect. In every issue raised, he has been rebutted by real calculations or a more sober statement of facts.”
McCorkle now acknowledges making mistakes. “The calculations are really much too complex to do by hand,” he told Spectrum in an interview last year, adding that the errors still don’t affect his conclusions. “There are some simple relationships, for example, between the number of megajoules required and the ratio of input power to output power.” He argued that the waste heat produced by the guns in itself is enough of a problem to make rapid-fire EM guns impossible. He also charged that the researchers “abuse classification” to hide their failures.
Much of the work on EM guns in the United States is indeed classified, admits Ian McNab, an expert on pulsed power sources at IAT. But, he points out, “we don’t classify anything; the Army classifies them. The Army has this idea that we should be doing this research for them, not the Chinese.” He counters McCorkle’s other contentions by saying, simply: “We’ve built these things, and they work.”
One of McCorkle’s arguments, though, seemed valid: if EM guns were so great, why was there so little research going on elsewhere? The British program, he argued, was an artifact of an EM gun given to them by the U.S. Defense Department. “I have also talked to the Germans and discovered their interest was based upon their belief that the U.S. somehow had a ’secret breakthrough’… otherwise it made no sense to them,” he wrote in his letter to Fair.
Had McCorkle looked further afield, he might have run across Wang Ying of the Ordnance Engineering College, in China’s Hebei province. Back in 1981, Ying had come across the proceedings of Fair’s first symposium on EM launch and decided to make the subject his life’s work. At first, he found few takers for his ideas, but in the last decade, he and his former students have established electromagnetic launch R&D programs at 22 academic and military institutions in China. With Richard Marshall, he also coauthored two textbooks on the subject.
Indeed, Marshall and Fair were both delighted to find like-minded colleagues in China. In September 2004, Fair’s keynote speech at the China EM Launch Symposium, at Dalian University of Technology, drew a standing ovation. Afterward, the head of Dalian’s electrical engineering department gave him a tour of their coilgun test facility. Today China is arguably the largest center of electromagnetic gun research outside the United States. At the 13th International EML Symposium, held in May 2006 in Potsdam, Germany, the Chinese accounted for 52 papers, second only to the United States, which had 72.
One intriguing Chinese project is the coilgun-based armor under development at Harbin Institute of Technology. Tank armor today consists of a thin layer of high explosive sandwiched between two metal plates; when hit, it erupts, thereby destroying conventional weapons such as shaped charges.
The Chinese armor would be one step ahead of such reactive armor. It uses a sensor to detect incoming shells, and then a coilgun flings a plate of armor to break up the shell before it hits the tank. One problem with this approach is that the projectile must be made of something other than iron, because the coilgun’s magnetic pulse would end up heating the iron rather than accelerating it. Harbin researchers have tried other materials such as aluminum but found it melts easily and is too weak for use as armor. In their experiments where steel armor was married to an aluminum coil, “the thrust force [of the incoming shell] not only didn’t decrease but increased a little,” according to a recent paper. [For other electric gun projects, see sidebar, "Electromagnetic Launch Takes Off."]
Comparable U.S. efforts in electric armor are classified, so it’s noteworthy that even this much is known about the Chinese program. But for whatever reason, Fair notes, Chinese researchers are surprisingly open about their work.
The Chinese aren’t the only ones pushing forward with EM gun technology these days. The 2006 symposium in Potsdam included participants from 16 countries, including France, Germany, Iran, Israel, Italy, Russia, and Sweden.
In the United States, the military’s interest in electromagnetic guns has revived, as has funding, with about $30 million per year now coming from the Army and the Navy.
The Navy is interested in the technology for its next generation of all-electric ships. The proposed Sea Strike railgun would launch tungsten projectiles at a velocity of 2.5 km/s to strike targets on land or sea up to 500 km away. Moving to electric guns would mean not having to store gun propellant and explosive ordnance onboard. Warships rarely sink because of a direct strike from a bomb or torpedo; rather, the attack causes fuel or munitions to explode, which then brings down the vessel.
The Army, meanwhile, is focusing on a railgun for a lightweight, all-electric ground vehicle that would launch kinetic projectiles against armored vehicles; like the Navy’s gun, it would have a muzzle velocity of 2.5 km/s. According to Fair, this speed has been chosen “as a near-term practical limit.” While faster projectiles require expensive nose tips to keep them from melting, relatively inexpensive nose tips now exist that can withstand the lower speeds.
Fair’s IAT, which saw its budget triple this year to more than $15 million, is now carrying out basic research for both the Army and the Navy. That work includes energy storage and pulsed power, projectile designs that can achieve deeper penetration in their targets, improved three-dimensional computer modeling of thermal and stress issues in EM launch, and railgun designs with reduced muzzle flash and noise.
While such efforts may ultimately lead to bigger and better guns, the real motivation for many researchers is still Earth-to-space launch. McNab is leading a consortium of the IAT, Texas Tech University, the University of Minnesota, and the University of New Orleans to build a high-altitude railgun for launching microsatellites into orbit.
As with earlier electric gun projects, though, much about this one remains to be worked out. “Both the launcher and the power supplies have yet to be invented that will do this job,” notes McNab. While integrated electronics that can withstand up to 25 000 g’s of acceleration have been successfully tested, hardening them to about 65 000 g’s may be needed.
Fair, though, remains undaunted. “We’re now just past the tipping point,” he says. Just as sailing ships gave way to steamboats and piston-driven prop planes were eclipsed by jet aircraft, he says, chemical propulsion will eventually cede to electromagnetic guns. “It’s inevitable.”
Electromagnetic Launch Takes Off
A sampling of EM gun projects in the works
Small Gun: A coil gun used for testing at Sandia National Labs.Photo: Randy Montoya/Sandia National Laboratories
The Institute for Advanced Technology at the University of Texas at Austin is leading a consortium to build an aircraft-based railgun that would launch microsatellites into orbit. For further information, see the paper by Ian McNab at http://www.emlsymposium.org/13th_papers/docs/EML004.pdf.
The European Space Agency is funding a feasibility study of a ground-based railgun to launch suborbital scientific probes and, ultimately, microsatellites. See http://www.esa int/SPECIALS/GSP/SEMNPS7O0MD_0.html.
The U.S. Naval Surface Warfare Center in Dahlgren, Va., is developing a railgun to deliver hypersonic projectiles at ranges in excess of 200 nautical miles within 6 minutes. The railgun will be incorporated into the Navy’s all-electric DD(X) Destroyer, now under development. See http://www.onr.navy.mil/media/releases/image_gallery/default.asp?categoryID=9.
The Ordnance Engineering College’s Institute for New Concept Weapons, in Shijiazhuang, China, is developing electromagnetic guns for, among other things, use in tank armor.
Sandia National Laboratories, in Albuquerque, is developing coilgun and railgun mortars that are designed to fire 120-millimeter-diameter projectiles with a muzzle velocity of 420 meters per second and kinetic energy of 1.6 megajoules [see photo, "Small Gun"]. See http://www.sandia.gov/LabNews/labs-accomplish/2005/mili.html.
About the Author
Carolyn Meinel is a science writer and IEEE member based in Sandia Park, N.M. She has consulted on electromagnetic gun technologies for SAIC (Science Applications International Corp.), the Institute for Advanced Technology, and DARPA.
To Probe Further
IEEE Transactions on Magnetics has published proceedings from the Electromagnetic Launch Symposium since the first meeting in 1980. Another source of papers from the 13th International EML Symposium, held in Potsdam, Germany, 22 to 25 May 2006, is the Web site http://www.emlsymposium.org.