Remember George Jetson and his flying car? That's the image that came to mind this week as reports were published about Chinese researchers working on submarine that would ‘fly’ in an ‘air bubble’.
The method has been around for decades and it's called "supercavitation". The idea is to increase the speed of an object by creating a bubble around it. The bubble reduces drag as it moves through the water enabling very high speeds. Theoretically, supercavitation could help a submarine reach speeds that will make the trip from Shanghai to San Francisco only about two hours long, faster than commercial aircraft fly.
But is it possible?
The short answer is "yes".
The Soviets used this trick on the Shkval torpedo in the ‘60s and ‘70s. That torpedo was capable of 230 mph but for no more than a few miles. And nearly all of these torpedoes were fired in a straight line because they had limited ability to turn.
However, the air bubble application has been limited to unmanned vessels, like the Soviet torpedoes. That brings up the two major problems with supercavitation bubble technology. First, the submarine would need to be launched at high speeds to generate and maintain the air bubble. Second, it is extremely difficult, maybe impossible, to steer with a rudder that’s inside a bubble without any contact with water.
The Chinese team claims to have solved these two issues but the project is shrouded in secrecy so no one is sharing details. Would you want to travel underwater in a bubble at high speeds? Give me the Jetson’s car instead please.