An idea that keeps popping up over the years is the idea of a cyclocopter or cyclogyro. The basic principle is to rotate a set of wings (or rotor blades) in a cylindrical motion. By varying the angle of attack as the airfoils travel around the circle, one can vector thrust in any direction normal to the rotational axis. The mechanics of such a system are more complex than that of a traditional helicopter. However, the forward flight speed would not be subject to the same limitations as that of a helicopter. In addition a properly working model would theoretically be more maneuverable than a helicopter, as the thrust could be vectored horizontally as well as vertically, rather than simply tilting the blade disc.
Prototypes are being built at the University of Maryland and at the Seoul National University, as seen in the youtube links.
The idea, however, is not new having been patented in 1927.
