The latest class of submarines can travel at more than 25 knots submerged.
But what if the Navy had a much smaller submarine that could travel four times as fast?
”The real reason we buy nuclear submarines instead of non-nuclear ones is that we’re not protecting the Gulf of Mexico,” said retired Navy Capt. James Patton Jr., president of Submarine Tactics and Technology in North Stonington. “We go halfway around the world, real quick. We get there and we stay there. Anything that would allow you to get a platform somewhere a long ways away pretty quickly would have great military value.”
That is why the Defense Advanced Research Projects Agency, which commissions research for the Defense Department, has given Electric Boat millions of dollars to design a vehicle that could potentially transport high-value cargo or small groups of people at 100 knots (about 115 miles an hour) in a program known as “Underwater Express.”
The technology, if developed, could revolutionize ocean transportation if it could be adapted to cargo and passenger ships.
The vehicle would travel inside a large gas bubble created in the water, a process known as supercavitation. The bubble reduces drag, since the drag is much lower in air than in water, allowing the vehicle to travel at high speeds.
Supercavitation is not new. The technology has been applied to weapons, but never to transport vehicles, according to DARPA.
”What we’re trying to do is come up with the sweet spot where science meets practicality,” said Franz Edson, EB’s director of submarine payload integration and strategic weapon systems. “The problem with the technology, the science, was you couldn’t go very far, you didn’t have any endurance and you couldn’t maneuver very well, so it was really kind of limited practicality.
”What these guys here have come up with is a way to dramatically increase the endurance and maneuverability of a body in supercavitating flight, so now you can really start to do things with it.”
Blowing out air to create the bubble that envelops the vehicle is wasteful, and a vehicle can only carry so much compressed air, so Jack Chapman, an engineer at EB, came up with a way to “mitigate that issue,” Edson said.
Exactly how is the gas-bubble creation process managed efficiently? Well, that’s a secret.
”It’s revolutionary, but we can’t tell you what it is,” said Jennifer Panosky, program manager of advanced programs and future payloads at EB.
”It’s not something we want other people to be aware of,” Edson said. “We’ve proven it works. We’ve set records for the longest supercavitating flight in a water tunnel. This has the potential to change ocean transportation.
”Ships would be much more fuel-efficient, or could use the same amount of fuel and instead of taking two weeks to get across the Pacific, they could get across in a matter of days. It’s pretty slick.”
DARPA has given EB about $26 million so far for the project, with another $12 million expected by the end, said Panosky.
EB initially pitted its design against one from Northrop Grumman Electronic Systems in Maryland. EB was chosen to build a quarter-scale unmanned vehicle, based on the concept of a full-scale size of 8 feet in diameter and 100 feet in length, for a demonstration in spring 2010 in the waters off Rhode Island.
The demonstration will include a 10-minute run at speeds of up to 100 knots with maneuvers, including depth control, to show the controllability of the vehicle, according to a DARPA statement.
At that point, the program will conclude and the technology will be available to the Navy for use in future systems as desired, according to DARPA.