Fastest Submarines
—Kyle Mizokami
Popular Mechanics (GETTY IMAGES)
IMAGINE A SUBMARINE SO FAST THAT IT CAN outrun a torpedo. That could soon be a possibility, thanks to a breakthrough propulsion method that Chinese scientists claim could produce the fastest submarines in the world. The approach would involve submarines using “laser propellers”—a system in which lasers create tiny explosions that would propel the submarine forward at previously unheard-of speeds.
The idea of lasers as a form of propulsion dates as far back as 1972, when it was originally proposed as a method for powering spacecraft. In atmospheric travel, the technology is fairly straightforward and understood: The underside of an aircraft is blasted with a laser that superheats the air underneath it, creating a plasma that explodes the air and propels the craft upward. But atmospheric laser propulsion has only been tested with scale models.
Now, researchers have proposed using the same method to propel objects underwater. The process involves covering a submarine with optical fibers, each thinner than a human hair. The fibers are then shot through with lasers, which create a plasma that vaporizes any water it comes into contact with, resulting in thrust. The vaporization also creates a shroud of bubbles the submarine can then pass through—one with much less friction than if the sub were passing through the surrounding seawater.
The engineers, led by researcher Ge Yang, believe this could be used to give Chinese submarines and weapons a major advantage. According to the South China Morning Post, it could “allow a submarine to travel faster than the speed of sound.” Furthermore, unlike the combination of turbines, gears, and propellers that power conventional submarine designs, laser propulsion would be virtually silent.
This combination of speed and silence is the holy grail of submarine warfare, rendering submarines nearly invincible against surface warships. Having such technology in the hands of China is frightening. Or it would be, if not for one detail.
Submarines survive by staying undetectable, and in the underwater realm that means being very quiet. But most submarines use propellers to move underwater, which creates pressure. This pressure in turn creates heat, which boils the water, forming a trail of tiny bubbles that eventually burst, creating a sound like “rocks going in a pipe.” The process is known as cavitation, something that fills submariners with dread.
The problem of cavitation makes this new laser propeller method impractical for undersea warfare. In a wartime South China Sea scenario, a Chinese submarine might outrun its American adversary using laser propulsion, but it would be easy to track. Eventually, it must stop—and everyone listening will know where it stops. Even if a submarine could outrun surface ships and other conventionally powered submarines, it could not outrun anti-submarine aircraft. ¦ |
