DARPA's Retractable Rotor Helicopter Concept

Boeing is studying the feasibility of the DiscRotor high-speed verticla-take-off and landing aircraft for DARPA. The aircraft takes off vertically like a helicopter, with telescoping rotor blades extended, then converts to fixed-wing forward flight by retrating the blades into the disc, which is then stopped. The aircraft the flies on its swept wing and dual ducted propellers. A 20%-scale model of the rotor will be windtunnel-tested in 2011.