DARPA Developing a Helicopter with a Spinning Disc Instead of Blades

DARPA is investing in developing a new kind of helicopter, one with what they're calling a Disc-Rotor. What makes a Disc-Rotor Helicopter different than a boring old helicopter? Well, when the blades start spinning fast, they're retracted into a disc. This disc continues to rotate, and it acts as a "rotating circular wing." The benefit of such a system would be to provide "mobility and responsiveness for troop and cargo insertion, satisfy an ongoing military interest for higher speed VTOL and hover capable vehicles, be survivable and bridge the gap in helicopter escort and insertion missions." Ho-Kay! I don't get it, but it sure will be neat looking, so I guess I'm on board. [The Register]