|
8
Nonstick Submarines

The Los Angeles Class Attack submarine USS Chicago (SSN 721) completes a training maneuver off the coast of Malaysia in July 2001. Kind of makes you realizes how friction could be a very formidable force for a beast like that.

Image courtesy U.S. Navy/Photographer's Mate 1st Class Kevin H. Tierney

Engineers have obsessed over submarine design for more than 200 years, but they've been unable to eliminate one of its most vexing problems -- friction drag, a force that opposes forward motion as water sticks to the surface of the outer hull. According to some estimates, this "skin friction" accounts for roughly 65 percent of the drag on submarines [source: Pike].

One solution? A polymer ejection system. In such a system, polymer is stored in a tank and then ejected through a series of ports as the submarine moves. The polymer flows over the surface and reduces the interaction of water molecules with the surface. Unfortunately, the system also increases the weight of the vessel.

Now scientists may have a better trick: coat submarines with a nonstick surface made from a revolutionary nanotechnology. The material doesn't look extraordinarily special to the naked eye. But if you view it under a microscope, you see that it contains tiny needles spaced just a couple millionths of a meter apart. The needles rest, like a layer of grass, on a surface of Teflon. When water hits the material, it encounters air trapped in the spaces between the needles. And this makes the material extremely slippery -- 99 percent less sticky than a normal Teflon surface without the nano-sized needles [source: BBC News].

Submarines coated in the nanotechnology would have far less friction drag and would require less fuel to propel them. And, yep, a raincoat made from the same material would protect you far better than the most expensive London Fog trench coat.

|