China sent waves, or perhaps bubbles, through the worlds of technology and transportation this week when a top Chinese scientist announced that China was developing a supersonic submarine — an underwater vessel that could cut through the water at speeds up to 3,600 miles-per-hour. This means a vessel could making the trip across the entire Pacific Ocean, from the east coast of China to the west coast of the United States, in about an hour and 40 minutes.
But are the Chinese for real here? And is such a thing as a supersonic submarine even possible?
The answer to the second question is, “Yes — in theory.” But the answer to the first question appears to be, sadly, “no.”
Let’s start with the source of this China announcement. According to The South China Morning Post, Li Fengchen, a professor of fluid machinery and engineering at China’s Harbin Institute of Technology, said last week that his research team was close to figuring out how to create a “bubble” around a moving submarine that would reduce friction to the point where the sub could rocket through the water at astonishing speeds.
“We are very excited by its potential,” Professor Li said.
The “bubble” to which he refers would be the result of a phenomenon known as “supercavitation,” which is a very real thing. What “supercavitation” means is heating the water around a moving object underwater so that a gaseous bubble envelopes that object allowing it to zip through the water as if it’s flying through air, rather than being slowed down by the drag of thousands of tons of seawater.
During the Cold War, the Soviet Union tested a torpedo that could travel up to 230 mph, using supercavitation technology.
But could this technology also be used on a much larger vessel, a submarine? Sure — in theory. But in practice, at least today or any time in the foreseeable future, the technology is simply unworkable.
First of all, while a torpedo travels in a straight line like an underwater bullet, a submarine with passengers and a crew would need to be steered. Steering inside a bubble is pretty much impossible.
Another problem is noise. Generating a supercavitation bubble is incredibly loud. That’s why even though supercavitation torpedoes exist, no one has ever used one in a war, because the noise of launching one immediately lets everyone for hundreds of miles know exactly where you are — and next thing you know, there’s a torpedo headed your way, as well.
Nonetheless, scientists are paid to envision things that don’t exist, so none of these issues have stopped Professor Li, who even sees Olympic swimmers like Michael Phelps someday wearing supercavitation swimsuits.
“If a swimsuit can create and hold many tiny bubbles in water, it can significantly reduce the water drag,” the China researcher said. “swimming in water could be as effortless as flying in the sky.”
But a supersonic Michael Phelps may be as far in the future as the proposed China supersonic submarine.