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Defense Speak Interpreted: The New Railgun Is Big News, But Can It Work?

Just as I was sitting down to finish this column, President Trump announced two new battleships, each equipped with a railgun. This is not just any railgun; it’s a 32-megajoule, with the same electrical power requirements as I have been reporting to you. Besides that, the battleships will be equipped with laser weapons—again, the ones I discussed in my November column. Both these are electric, not energy-propelled weapons.

A railgun is a weapon that uses electromagnetic force to launch projectiles (sabots) at high velocities, eliminating the need for chemical propellants like gunpowder. A railgun consists of two parallel conductive rails and a conductive projectile that completes the circuit, causing a massive electrical current to generate a strong magnetic field that accelerates the projectile along the rails. Railguns are used for long-range, high-precision strikes, air defense, and counter-battery fire, with potential advantages including cheaper ammunition, larger magazines, and a higher rate of fire compared to conventional weapons. However, there are various disadvantages that have so-far prevented railguns from becoming operational.    

Let’s look at how it operates, its advantages, and what has prevented the deployment of the weapon.  

First, a railgun has both a unique “barrel” with a unique projectile. No traditional barrel is required as two very conductive rails are mounted in parallel. The biggest consideration is that each rail must conduct on the order of 1 million amps. Now plug that into your copper wire equivalent. At 1,000 amps, it requires a square inch of copper, thus 1 million amps requires something over 30 x 30 inches of solid copper. We can allow the copper rails to heat, and if we add liquid cooling it will thus lessen the cross section. Ultimately, if we could get a superconductor into a “rail” shape, it could be a reasonable dimension. But that’s a lot of very expensive superconductor material—$4,000 to $10,000 a pound—before even considering liquidified gas cooling.   

Now, the projectile (sabot) is another story. Remember, the current must pass through the projectile to complete the circuit. But the sabot must be dense enough to carry massive kinetic energy to the target (explosion on impact is not capable). There is limited capability for an explosion after impact compared to “high explosive projectiles carrying “energetics.” The principal destruction will be from kinetic impact affects alone.  So, the projectile material choices have evolved down to tungsten or graphite. The projectiles leave the gun at hypersonic speed: Mach 5, 7, or even 10 have been demonstrated.   

So, Why Don’t We Already Have Railguns?
There are two considerations holding back railguns: materials and the electrical power required to operate them. 

First, the sliding contact up the barrel creates massive friction between the sabot and the rails. This friction limits the number of times the railgun can be fired before the barrel becomes pitted, eroded, or otherwise damaged. All the advantages of possible continuous operation and the ship not carrying energetics goes out the window if the weapon can only be used 30 times or so before barrel needs to be replaced. 

Second, and important to electrical engineers, is the generator/capacitor combination needed to fire off a megajoule sabot, say every 10 seconds. (Did Trump say he wanted a 34-megajoule railgun?) My sources say 100,000 kilojoules is about 134 horsepower—similar to a small Volkswagen.   

What capacitance does it take to store 1 million amps of power? I will close out this column with this direct quote from my GeminiAI source, and you will see the problem. 

A 1-megamp (1,000,000 Ampere) current discharge requirement is characteristic of extreme pulsed power applications, such as large-scale industrial railguns, experimental nuclear fusion reactors, or massive specialized surge capacitor banks.

Based on current technology and research, a 1-megamp discharge requires a massive, high-voltage supercapacitor bank rather than a single component.

Key Considerations for 1-Megamp (MA) Capacitor Storage 

Massive capacitance requirement: To deliver 1 MA (1,000,000 Amperes) even for a fraction of a second, the total energy stored

(E=1/2 CV²) must be enormous. A supercapacitor, unlike a battery, discharges its energy almost instantly.

• Voltage is critical: High current requires high voltage. To move that much charge, systems often operate at hundreds or thousands of volts (e.g., 100V-500V or higher), with thousands of Farads of capacitance.
• Energy density: While supercapacitors can discharge 10-25 kW/kg, they have low energy density compared to batteries.
• Safety and physical constraints: At these levels, the magnetic forces between capacitor plates can be destructive. The bank must be designed with extreme low inductance and robust structural support to handle the surge. 

Real-World Examples 

• Industrial/experimental: Research indicates that 20-25 megajoules (MJ) of capacitive energy storage has been used in experimental projects (like the Shiva Laser system), with upgrades proposing 150 MJ for specialized loads.
• High-power banks: A 1000 Farad 12V-16V bank can deliver roughly 8,000 watts of power for starting motors or car audio systems. Reaching 1 Megamp requires chaining thousands of these units in parallel, which is generally only feasible in heavy industrial or research contexts.
• Supercapacitors: Supercapacitors (or Ultracapacitors) are ideal for this because they offer over 1 million charge-discharge cycles.

Limitations 

• Instantaneous power vs. duration: A 1 MA pulse will discharge in milliseconds, not hours.
• Heat: Even with high efficiency, the internal resistance of the banks will generate massive heat, requiring robust thermal management.
• Cost: Supercapacitors for high power are extremely costly, with specialized systems often exceeding $10,000/kWh. 

Railguns make for great press releases, and on paper, they promise a future with fewer energetics, deeper magazines, and hypersonic reach. But physics, materials science, and electrical engineering don’t bend to enthusiasm or politics. Until we solve the very real problems of rail erosion, heat dissipation, and megamp-level power storage in a compact, affordable, and reliable form, the railgun remains more of a laboratory achievement than a fleet-ready weapon.

As I’ve said before, the technology is fascinating and the potential is real, but the gap between “big news” and operational reality is still measured in megajoules, tons of hardware, and a great deal of hard engineering work yet to be done.

Denny Fritz was a 20-year direct employee of MacDermid Inc. and retired after 12 years as a senior engineer supporting the Naval Surface Warfare Center in Crane, Indiana.