MARSEILLE, France (Reuters) – European group Eurocopter showed off a revolutionary winged helicopter on Monday, in a bid to counter U.S. rival Sikorsky's efforts to break the speed barrier by rewriting rotorcraft design rules. The X3 hybrid helicraft -- which combines forward-facing propellers astride two short aircraft wings with the familiar overhead rotor blades seen on any normal helicopter -- was unveiled following months of secrecy.