Robotic porpoises

I recently started reading Roland Piquepaille’s site again; it’s got some darn good stuff on it. This item caught me eye: Seagliders Break Endurance Records. A seaglider is an underwater airplane, or rather an underwater glider. Take a look at the size of the “wings” and you’ll get an idea of the difference between flying through water and flying through air. A much smaller wing will do the job in water. You get the same picture when you think about a sailboat as an airplane with one wing (the keel) in the water, and the other wing (the sail) in the air. The forces nearly balance despite the vast difference in wing area. The beauty of a seaglider is that it can glide incredibly cheaply by changing its buoyancy. I wrote about this last fall, but the technology seems to have taken a real leap forward in the meantime. These robot porpoises are swimming across the Pacific, reporting by satellite to their masters. There must be lots of people jumping at this idea.