by DAVID AXE
Navy SEALs could speed towards shore in a mini-sub traveling at speeds greater than 100 knots, if one $20-million fringe research program works out. That’s five times faster than the top speed of today’s SEAL mini-subs, which are essentially updated versions of World War II submersibles.
“Underwater Express,” under development by the Navy, DARPA and General Dynamics, takes advantage of a phenomenon called “supercavitation.” That’s when an underwater vehicle surrounds itself in a low-friction vapor shroud, like a drop of oil slipping through water. The Soviet Union designed a supercavitating torpedo, the Shkval, that can reach 200 knots.
The Navy needs a new SEAL sub. The sea service had intended to replace the old subs with the new Advanced SEAL Delivery System — the first of which, pictured, entered service in 2003 — but the only ASDS sub caught fire in Hawaii, late last year. The Navy was never happy with the newer sub’s performance, and this week decided not to repair the burned example, or to buy additional copies. Instead, the Navy is investing $40 million to study a future “Joint Multi-Mission Submersible.” It’s not clear whether Underwater Express will be ready in time to fill that requirement. The first scale model is slated to enter testing next year.
Underwater Express has to overcome two very big technical obstacles — so big that “some observers are not sure that supercavitators will ever emerge from the concept stage,” according to Nick Adde, writing in the latest Unmanned Systems. Supercavitating vehicles like Shkval travel very fast, but really only in a straight line — and not very far. To be effective, an operational version of Underwater Express will have to be maneuverable and pack enough power to transport SEALs up to 100 miles, between the full-size submarine “mothership” and the enemy’s beach.
(Art: via Navsource.org)