Although this may be old news to some, it is worth revisiting at a time when new helicopter concepts are generating increased research funding. In 2008, the Defense Advanced Research Projects Agency (DARPA) announced its plans to award the Boeing Company a Phase I contract for the continued development of the DiscRotor concept. According to an article for Aviation Today, Boeing teamed with Virginia Polytechnic Institute under the initial Phase 0 contract to conduct trade studies, wind tunnel analysis, computational fluid dynamic (CFD) studies, hover rig testing, and risk reduction planning.
Little information has been released about this conceptual rotorcraft design; however, it is envisioned to be a high-speed search-and-rescue aircraft according to “New Helicopter Designs Take Off”, an article in the April 2011 issue of Aerospace America. Artist renderings and preliminary concept models show what appears to be a conventional aircraft configuration with two wing-mounted engines. Sitting atop the fuselage is a large disc, which has two primary configurations: one where blades are protruding from the disc and one where they are retracted within the disc. While the blades are out of the disc they will act like a helicopter rotor to produce vertical flight capabilities. As the aircraft transitions to forward flight the blades will retract into the disc, which may then be considered a “third wing”. The aircraft has been shown to not have a vertical tail, but rather large winglets on each tip of the main wing that may be used for yaw stability in forward flight. The two wing-mounted engines may be used for counteracting the torque generated by the rotating blades.
Some of the design goals for this vehicle are to combine the speed and capacity of a fixed-wing aircraft with the vertical maneuvering capabilities of a helicopter. Because little information has been released about this particular project, only time will tell about the expected duration of missions for which these aircraft may be used. It will also be interesting to see the noise signatures of the DiscRotor aircraft during vertical flight, forward flight, and transition flight periods if this design progresses to the full-scale prototype stage.