Super Stealth Submarine -- Hide Your Kids, Hide Your Wife!

[Intel Source: Eagle1] Here's an article that follows up a previous report of a DARPA project that speculates that new acoustic energy-absorbing "metamaterials" could render submarines "invisible" to sonar. Excerpt:

The researchers tested their cloak’s ability to hide a steel cylinder. They submerged the cylinder in a tank with an ultrasound source on one side and a sensor array on the other, then placed the cylinder inside the cloak and watched it disappear from their sonar. Curious to see if the hidden object’s structure played a role in the cloaking phenomenon, the researchers conducted trials with other objects of various shapes and densities. “The structure of what you’re trying to hide doesn’t matter,” Fang said. “The effect is similar. After we placed the cloaked structure around the object we wanted to hide, the scattering or shadow effect was greatly reduced.” The geometry is not theoretically scaled with wavelengths.

I'm glad DARPA is working on stuff like this; in case there is a possible breakthrough in areas like this, I'd much rather that we make it. As far as the possibility that this material could be used to "hide" submarines, however, I see a couple of obvious problems: 1) I doubt that you could make a material of this nature retain its characteristics while expanding and contracting with the submarine's hull as it changes depth, and 2) the frequency range mentioned in the article doesn't seem that relevant for ASW.

When discussing this article, please don't mention any actual frequency ranges of interest.

[Here's another article on a potential new Navy breakthrough. This one involves skimmers with laser beams on their decks.]