Posted by John Keller
There's just no way to understate the military's future need for high-power electronics. Electric-drive vehicles, all-electric aircraft, and aircraft carrier catapults are just some of the potential applications.
Yet the emergence of electromagnetic railguns has raised the bar dramatically for high-power electronics. The U.S. Navy plans to use these weapons aboard future surface warships to shoot non-explosive shells at a speed of March 8 -- eight times the speed of sound, or roughly 6,000 miles per hour.
At that speed you don't need explosives; the kinetic energy alone is enough to make vehicle-size objects disappear in balls of fire. Forget artillery shells and missiles. Fire an electromagnetic railgun at a target 10 miles away and the projectile gets there in less than six seconds. That's not much time to react. You'd never hear it coming; you'd be lucky even to see it.
Now get this: the Navy wants electromagnetic railguns with ranges of hundreds of miles. Shot a target 200 miles away and the projectile gets there in about two minutes. A Harpoon anti-ship missile would take about 22 minutes to fly that far. It's not hard to see how batteries of electromagnetic railguns -- especially those that could fire rapidly -- might be able to overwhelm enemy air defenses very quickly.
Believe this is science fiction? Think again. The Office of Naval Research has taken delivery of a functional, 32-megajoule Electro-Magnetic Laboratory Rail Gun from BAE Systems, and the gun will be demonstrated this week at the Naval Surface Warfare Center in Dahlgren, Va. The Navy envisions 64-megajoule electromagnetic railguns for future shipboard use.
The difficulty of deploying future electromagnetic railguns might not lie in the technology necessary to build these weapons, but in producing the incredibly large amounts of electricity necessary to operate them.
Think of the kind of electromagnetic railgun the Navy wants for future warships. It takes 64 megajoules to shoot it. That's equal to about 18 kilowatt hours, or about the same amount of power an average American household uses in an entire day. Those future warships carrying these kinds of weapons are going to need amazing power plants.
Think of the generators that will be necessary to operate the electromagnetic railgun. This requirement for electricity production is likely to have a profound influence over future ship design.
It looks like the designers of high-power electronics and components have their work cut out for them. Ready or not, industry, the Navy is going to need a lot of electrical power, and very soon. We wouldn't want those electromagnetic rail guns to be all dressed up and have nowhere to plug them in.
This rail gun is a defense paradigm changing technology.
ReplyDeleteIn theory, the absolute limiting value of electromagnetically launched projectiles is the speed of light or C. Obviously, according to special relativity, attainment of C for a projectile of finite rest mass would require infinite energy input. However given the absolute limits of C and infinite kinetic energy, there is lots of room for electromagnetic gun technology to improve.
Some theories that hold that there are absolute limits to the intensity of electric and magnetic field hold that such fields can achieve a maximum strength of about 10 EXP 55 Volts/meter and about 10 EXP 55 Tesla respectively. At these field levels, one cubic meter of space occupied by such a field would contain an electrical or magnetic energy 10 EXP 30 times greater than the entire mass energy content within the visible universe. Field levels greater than these in a pure vacuum might accordingly cause the vacuum to break down into single magnetic pole particles such as monopoles and perhaps other bazaar entities.
On a much more practical note, electromagnetic guns that would use solenoid highly conducting carbon nanotube materials with tensile strengths exceeding mild grade construction steel by a factor of 60 might enable magnetically propelled hardened steel projectile to reach tens of kilometers per second. The extreme tensile strength of these carbon nanotube materials might permit magnetic field strengths into the hundreds of Teslas in a repeatable manner.
In short, electromagnetic guns are an awesome technology. In a world where enemies of freedom would like to take down the U.S. and its allies, I see no problem morally with developing such systems, improving them, and deploying them. The horrible news about how Alqueda probably conned two innocent mentally retarded Iraqi women to carry bomb vests packed with dynamite and ball bearings which were detonated remotely to kill scores or market goers only reinforces my opinion for our need to keep a technological edge on our ruthless adversaries. We can aim for the ultimate goal of disarmament but even the late great Pope John Paul II said it is not practical nor feasible for the U.S. to disarm unilaterally. Our enemies certainly will not.
Thanks;
Jim Essig
John,
ReplyDeleteGood information on the EM Gun, but I wanted to add a few more technical details to help clarify the real problem with these systems that the Navy faces. As an electrical engineer who has worked on EM Guns, I have some expertise in this area.
The real power issue is with the pulse power system required to fire the weapon system. You can charge up the system every 12 seconds, but you discharge it in a matter of a few milliseconds. There are a couple of techniques to do this, but all of them are large, significantly complex, and have issues of long-term reliable operation. The least technically complex (in my opinion, and I say this because all methods are extremely difficult to implement) is a capacitor based system. The current baseline for energy storage in capacitor systems (from General Atomics presentation at IEEE PPC July 2009) is 2J/cc. Thus a 64MJ system would require a capacitor system approximately 32 cubic meters, assuming 100% packing density, which is not possible due to heat generation and maintenance issues. A more realistic number might be 50% packing efficiency, making the space requirement 64 cubic meters minimum. Even still, on board a ship, this is not a significantly large requirement for space.
All in all, this is an important capability that the military needs to continue to pursue. The capabilities that this system provides are tremendous, especially if you look at the current developmental budget being directed towards it. In FY10, the Navy was given approximately $37M for EM Gun and directed energy weapons. Compared to other weapon systems such as the $120M in FY 10 for the Airborne Laser, this is a relatively small investment. Although the EM Gun has been intermittently worked on since the 1980's, we are finally getting to a point technology wise, where a deployable system is possible (once again in my opinion) in the next 10 to 15 years if we continue to invest in this technology.
MAJ Brian Souhan, student, ILE Class 10-003, Ft Lee, VA
-The views expressed in this blog are those of the author and do not reflect official policy or position of the U.S. Army, Department of Defense, or U.S. Government.