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A thin sheet of multi-walled carbon nanotubes suspended in cellulose tissue can create ultra-low frequency underwater sound waves with ease.  (Source: University of Texas, Dallas)
If a submarine covered in carbon nanotubes drives in the ocean, can you still hear it?

If there is one thing navies the world over want, it's more efficient sonar and the ability to hide their own submarines from it. Of course, the downside of such a technology is the heightened probability of more mid-ocean collisions.

Last summer, University of Illinois at Urbana researchers spoke of a new metamaterial that could be used to, in essence, guide incoming sonar waves around the hull of a submarine. The material also holds promise for super-high-definition ultrasound machinery for hospitals.

University of Texas at Dallas researchers have developed a more task-oriented device that may promise not only improved audio cloaking technology, but improved sonar systems in the same fell swoop. The device, composed of some electronics and a thin sheet of multi-walled carbon nanotubes, can be used to generate ultra-low frequency sounds without using large amounts of energy or taking up much additional space or weight.

Nanotubes are perfect for this sort of underwater use -- they are both remarkably resilient and hydrophobic. Due to their inherent dislike towards each other, carbon nanotubes create a small pocket of air around themselves when submerged in water. It's this pocket that does the heavy lifting for UT Dallas's system.

After being energized, the sheets of carbon nanotubes create their sound waves by being heated and cooled. This in turn generates pressure waves in the air pocket, which directly transfer to the water around it. These generated sound waves could be use both for the submarine's own sonar system, as well as noise-canceling incoming sonar pings from other subs.

Not only can the sheets be used for sonar and cloaking, but by layering them, additional sheets can be used to reduce boundary layer loss, friction and turbulence. And not just for submarines -- aircraft could benefit from the technology as well.

Each layer of of the device's nanotubes is about 20 microns thick and has virtually no weight, being 99% porous. Easily imaginable are the space and weight savings to marine craft currently equipped with modern sonar. The sheets can be applied to virtually any shape of hull, easily conforming to curves and angles. The only drawback is the lack of (reported) computer system to manage the complex task of audio wave direction, noise cancellation and temperature management for friction control in different water temperatures.


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manufacturing
By kattanna on 6/15/2010 11:26:34 AM , Rating: 2
what i find interesting about the article is the assumption that manufacturing such quantities isnt an issue.

is our manufacturing level of nano tubes really up to the task of being able to coat an entire sub? thats a LOT of surface area




RE: manufacturing
By niaaa on 6/15/2010 1:18:24 PM , Rating: 2
In the US they produce only a few tons of nanotubes each year, and under laboratory conditions. There is a lot to be done to permit large scale production yet.


RE: manufacturing
By roadhog1974 on 6/15/2010 11:04:16 PM , Rating: 1
You can do a lot with a 1/2 trillion dollar budget.


RE: manufacturing
By SSDMaster on 6/16/2010 3:58:13 PM , Rating: 2
Wrap subs up with nano material, or go to Mars 64 times in a row with the same $$$...

I think I know which one is more likely to happen.


RE: manufacturing
By MedLR on 6/17/2010 1:39:22 PM , Rating: 2
Neither will happen. Our tax dollars were already used to save the banking and automotive industries. Now if we could just pay back the $900 Billion to the countries that we owe...


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