Sikorsky's Quest For A Hi-Speed Heli

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Helicopters can perform amazing vertical feats, but their Achilles' heel has always been forward speeds limited by the retreating blades' ability to create lift. Usually, the machines max out at about 170 knots. Efforts to increase forward speed have previously resulted in degraded hover performance. While Bell inches its Bell/Agusta 609 tiltroter's nacelles toward full airplane mode, Sikorsky Aircraft announced this month it plans to build and test a demonstrator for a new class of helicopters that will cruise at 250 knots (Bell's 609 aims for 275) while meeting or exceeding all the usual vertical flight capabilities of rotorcraft and without using tilting rotors on wingtips. The demonstrator will feature a coaxial design (two counter-rotating rotors on the same vertical axis) and a pusher prop to supply auxiliary propulsion. Sikorsky plans to build and fly its X2 Technology Demonstrator helicopter at its Schweizer Aircraft subsidiary by the end of 2006. Preliminary design work for the demonstrator is finished and parts fabrication for the aircraft is underway. The announcement was made at the American Helicopter Society International's annual technical forum in Grapevine, Texas, where Sikorsky unveiled new scale models of X2 Technology helicopter concepts in various weight classes and configurations. "We initiated X2 Technology convinced that the most productive and flexible helicopter is a helicopter which is capable of a significant increase in speed," said Sikorsky President Stephen Finger. "Customers are demanding greater speed but without sacrificing any of the unique capabilities that make helicopters the ideal platform for countless civil and military missions." X2 Technology aircraft will hover, land vertically, maneuver at low speeds, and transition seamlessly from hover to forward flight like a helicopter. In a high-speed configuration, one or more pusher props are part of an integrated auxiliary propulsion system to enable high speed with no need to physically reconfigure the aircraft in flight.