Researchers To Build Underwater Airplane

coondoggie writes to tell us that DARPA seems to still be having fun with their funding and continues to aim for the "far out." The latest program, a submersible airplane, seems to have been pulled directly from science fiction. Hopefully this voyage to the bottom of the sea is of the non-permanent variety. "According to DARPA: 'The difficulty with developing such a craft come from the diametrically opposed requirements that exist for an airplane and a submarine. While the primary goal for airplane designers is to try and minimize weight, a submarine must be extremely heavy in order to submerge underwater. In addition, the flow conditions and the systems designed to control a submarine and an airplane are radically different, due to the order of magnitude difference in the densities of air and water.'"

Comments

Re:Steve Fossett

[element-o.p.]

Not really. "Flying" requires using aerodynamic or hydrodynamic properties to provide lift or buoyancy. Submarines use ballast to sink, then expel the ballast to surface. Both airplanes and submarines use similar structures for controllability, but a submarine doesn't fly any more than a zeppelin does.

If you think about for a minute, you will see why a heavier-than-water submarine that flies is a really bad idea. However, I have seen designs for positive buoyancy submersibles that fly down, and would therefore surface if the engine were to fail.