Sikorsky is readying its X2 compound helicopter demonstrator for first flight in late 2007 or early 2008, the U.S. manufacturer announced here at the Paris Air Show. The hybrid design, which looks like a helicopter with two contrarotating coaxial main rotors and one tail propulsor, already had its fly-by-wire system tested in a small Schweizer 333 helicopter. The actual X2 has undergone engine and drive train ground tests.
According to Sikorsky, X2 technology should yield aircraft that retain helicopter capabilities while flying faster and longer. The manufacturer is talking about 250 knots and 500 nautical miles. To attain higher airspeeds, the aft propulsor provides forward thrust while the control system automatically slows down the main rotors to keep blade tips subsonic. Compared to a tiltrotor, the X2 will fly slower but does not need an in-flight reconfiguration.
