The Daily Caller
31 March 2015
Physicists at the Nanyang Technological University in Singapore have published a new paper which lays the theoretical foundation for how submarines, with a special coating, could deflect sound.
This means submarines would be completely undetectable by sonar.
Authored by physicist Baile Zhang and his colleagues, the paper, published in Physical Review Letters, proposes that the same technique could apply to any 3D object. Normally, sonar waves hit the hull of a submarine and the sound scatters, which creates an echo, revealing the location of the sub.
Under Zhang’s system, sound waves sent out by sonar would hit a special material called a phononic crystal. This material is acoustically tuned and would manipulate the sound waves, such that they would bounce off and on the submarine in a loop, until finally the submarines passes through undetected.
For now, the coating is just a theory. But unlike other more fantastical proposals, Zhang says he and his team will get right to designing the coating in just a few months, as the project is very feasible.
“In principle, if a sound wave can be smoothly guided around the submarine without reflection, it can escape detection from sonar, because the sonar works by detecting deflected signals,” Zhang said, according to Popular Mechanics.
Zhang’s approach is particularly interesting because it avoids traditional problems which have plagued stealth engineers for decades. So-called “irregular protrusions” from objects ruin cloaking abilities, but a coating of an acoustic topological insulator, according to Zhang, would work on an object of any shape. Phononic crystals could also potentially be used to make hearing aids function more effectively in channeling sound through the ear canal.
Another method of stealth submarine technology is underway at the Paris Diderot University in France. Physicist Valentine Leroy thinks that bubble-filled material could kill a sonar signal by as much as 99 percent. How it works is that the bubbly coating absorbs and then virtually dissipates the sound.
And the members of the small Egg Harbor Township Base are excited that the world will finally get to see the memorial, which is next to the Veterans Memorial Park in Somers Point, and is highlighted by a World War II torpedo that was hard to find — and even harder to find parts for.
They’re just disappointed that some of their own vets won’t be lucky enough to see the results of all their work.
Tom Innocente, the group’s commander, can count nine members who have died since the memorial project started — “And half of them were World War II types,” by his estimate.
The latest was just last week — Hoyal Cass, of Egg Harbor Township, was 91 when he died. His obituary said “Chief” Cass spent more than 20 years on subs, from World War II through Vietnam, and his “greatest joy in life was his service in the United States Navy submarines.”
Lee Gilbert, the group’s vice commander, is only being complimentary when he calls Cass “a tough old bird.” Gilbert says that Cass was active in the U.S. Submarine Vets until the end — he came to one of the group’s meetings shortly before he died.
When the members started this project, it’s fair to say they didn’t realize just how complicated — or expensive — it would be.
“We knew it wouldn’t happen overnight,” says Gilbert, who lives in Somers Point and served on three submarines during the Cold War era, from 1951-59.
“There was a lot to it, and it involved a lot of money we didn’t have,” Gilbert adds. This led to annual fundraising events, including an ongoing project of selling memorial bricks to help pay for the project. “With a group as small as ours, just 20 or 25 guys, it took a while.”
But submarine vets are used to being in a small group. When Bill Capo, of Absecon, was on three different submarines in World War II, in both the Atlantic and Pacific oceans, he was usually one of a crew of 75 to 80. By the U.S. Sumbarine Veterans’ statistics, just 16,000 or so Americans served on submarines during that war.
They also unfortunately got used to very high levels of danger. The vets group says that about 3,500 Americans in the “silent service” died in battle — or more than one out of five. The U.S. lost 52 submarines in the war, out of a total of 288 subs.
Capo is 87 and retired now, but he says that in his days on the submarines, they had to surface about every 30 hours. The crews knew that put them in harm’s way, but they needed to get fresh air and clear the smoke out of the diesel subs of the era.
But by the time Gilbert and Innocente, also of Somers Point, and Don Brown, of Northfield, were on nuclear-powered submarines in the Cold War, the boats could stay underwater for months at a time.
“We would leave port, and once you went down, you’d stay under until you came back,” Brown says. “The longest I was underwater was 69 days.”
Innocente, the commander, added that he was on a submarine that stayed submerged for 99 days.
None of these vets is sure how many miles he covered underwater, but Gilbert says that one mission could account for tens of thousands of miles.
One holdup for the Egg Harbor Base was that they had a hard time coming up with the centerpiece for their memorial.
“We specifically wanted this model,” says Innocente, pointing to the Mk14 torpedo — because that weapon is credited with sinking 4 million tons of enemy ships during World War II.
But they were having trouble locating a surviving torpedo until they contacted a high-ranking Navy officer with local roots. Rear Admirial Mark H. Buzby is retired now, but he’s a Linwood native who will be a featured speaker at the April 11 dedication of the memorial, and he was instrumental in helping the Egg Harbor Base deal with the Navy to track down a rare torpedo, the local vets say.
That torpedo didn’t have a nose, though, so the vets had to find a company that could make one. They located a manufacturer of modern torpedos that could do the job — with the help and counsel of one worker’s father, who happened to be another World War II sub vet.
That nose cone cost $8,000 as a custom order, but the Egg Harbor Base vets say they’ve had a lot of support in their long mission. By Innocente’s estimate, their project would have cost them almost $100,000 so far — except that they’ve gotten close to 90 percent of the work and material donated.
And now they’re almost ready to unveil the results at the formal dedication — although volunteer preparation work was still going on Sunday, the base commander said.
Plus some people got a sneak peek at the memorial Saturday, the day World War II vet Hoyal Cass was buried. His funeral service was right down the street in Somers Point, and on its way to the Atlantic County Veterans Cemetery in Estell Manor, Cass’ funeral procession passed — and paused, briefly but respectfully — at this new memorial to submarine vets of all wars.