The US Navy's electromagnetic railgun project notched up a successful test yesterday. The radical new protoype weapon, operated by the the Naval Surface Warfare Center Dahlgren, fired* shot a hypersonic aluminium slug at approximately Mach 7.5 to generate muzzle energy of 10.6 megajoules.
The US navy is interested in the kit for a number of reasons. For one, its next generation warships are expected to use electric drive systems, meaning that they will be have 80 megawatts or more on hand. If this power can be used to put violence onto the enemy as well as driving the ship, that's good news for logistics and supply. The only ammo you need is solid shot with guidance fins; there's no need for tons of high-explosive warheads and low-explosive chemical propellants for regular shells and missiles. These are replaced by nice simple fuel for the ship's engines.
The lack of exploding warheads could offer a chance to deliver more surgical strikes, too. They could take out a single vehicle from far out at sea, perhaps, rather than pulverising a whole area like present-day cruise missiles. This kind of thing is very trendy nowadays in military circles, though the problem of getting the right vehicle remains a tricky one.
Furthermore, even the ritziest missiles struggle to get above Mach 3-4, especially over any distance; thus the railgun slugs would be quicker to arrive when bombarding shore targets. They might also be good for shooting down fast-moving flying things.
Indeed, if the cannon could aim quickly enough and the hyper-bullets could steer well enough in flight, lighter-calibre weapons might tip the balance of naval warfare back in favour of surface craft. Ever since the Battle of Midway, sailors have reluctantly been forced to accept that aircraft win sea battles, not ships. But railguns might demote aircraft carriers from their current big-dog naval status and bring in electric dreadnoughts as the capital ships of tomorrow, able to sweep the skies of pesky aircraft or missiles as soon as they dared show themselves above the horizon.
It's easy to see why navies like the idea of electric hypercannons, then. But there are a lot of problems to be overcome. For one, the gun barrel tends to come apart after just a few shots. For another, packing a steady hundred-megawatt supply down into ultra-brief 64 megajoule pulses isn't simple.