Superfast Sub

The Underwater Express (UE) will prove that a “supercavitating underwater craft is controllable at speeds up to 100 knots.”

That’s the clinical way the Defense Advanced Research Projects Agency (DARPA) chooses to illustrate its new submarine. Another way to describe the UE is: This 100-ft boat will fly. Perhaps not literally (as it is a boat, after all). However, “supercavitation” is a moniker normally preserved for torpedo speed. The phenomenon takes place when an object moves through the water so fast it generates a bubble of gas around itself. Drag is reduced on the order of 60 to 70%.

Three years after it was initially investigated by DARPA and Electric Boat (www.gdeb.com), a General Dynamics (www.generaldynamics.com) contractor, the Defense Department agency has approved an Electric Boat plan to 25 ft. scale prototype.

The program calls for a demonstration of the ability of a model to operate at 100 knots for 10 minutes. If it works and there is the go-ahead for a full-scale sub, it would, in effect, blow old submersible designs, well, right out of the water.