Chinese researchers say it's possible they may one day have high-tech submarines capable of a journey across the width of the Pacific Ocean in just under two hours.
Scientists from Harbin Institute of Technology say they've made great steps in updating a Cold War-era Soviet military technology that uses a phenomenon known as supercavitation that can allow submersible craft to travel at high speeds.
In supercavitation, and entire submerged vessel would be enveloped in a surrounding air bubble of gases emitted from the sub's nose, removing friction with the water and allowing it to reach speeds of thousands of miles an hour.
At those speeds a trip from Shanghai across the Pacific to San Francisco might take less that two hours, the researchers said.
The Russians reportedly used supercavitation to create torpedoes that, once launched, reached speeds of around 230 mph.
"We are very excited by [the technology's] potential," lead researcher Li Fengchen, a professor of fluid machinery and engineering, told the South China Morning Post.
One hurdle, the researchers acknowledge, is the difficulty of steering a vessel once it is surround by its air bubble and traveling at high speed.
The Chinese researchers say one solution would be for the vessel to coat itself in a liquid while inside the bubble, forming a membrane that, if manipulated, would control the amount of friction and drag on certain parts of the vessel, allowing it to be steered.
"By combining liquid-membrane technology with supercavitation, we can significantly reduce the launch challenges and make cruising easier," Li says.
Supercavitation has attracted research by the U.S. military, with reports the Defense Advanced Research Projects Agency, or DARPA, was once working on the technology.
Some experts, however, have expressed doubts as to the feasibility of creating such supecavitation vessels.
"The size of the bubble is difficult to control, and the vessel is almost impossible to steer," says Wang Guoyu, who heads the Fluid Mechanics Laboratory at the Beijing Institute of Technology.
If any portion of the sub were to breach its bubble, the whole bubble would collapse from the density difference of the surrounding water, he says.
How that could be avoided is just the kind of question that the Harbin researchers have been keeping mum on, which Wang says is no surprise given the technology's obvious military applications.
"The primary drive [behind the research] still comes from the military, so most research projects are shrouded in secrecy," he said.
