Eurocopter announced today that its X3 compound helicopter demonstrator flew at 255 knots in level flight on Friday near Istres in southeast France. Also part of the unofficial speed record was a descent at 263 knots. These speeds are just a few knots higher than those the Sikorsky X2 semi-compound demonstrator attained in 2010.
“The X3 performed exactly as it has so far throughout its flight envelope, exhibiting outstanding stability and providing a low vibration level without any anti-vibration system,” test pilot Hervé Jammayrac said. During the high-speed run, it was flying at about 10,000 feet with landing-gear doors, which it did not have previously, and a new fairing on the rotor hub. The rotor-hub fairing might also provide benefits to other Eurocopter models, according to flight-test engineer Dominique Fournier.
To date, the X3 has flown 140 hours since its 2010 introduction. Based on the AS365 Dauphin airframe, it features a single main rotor and stub wings that each carry a propeller. While helicopters usually fly at 140 to 150 knots in cruise, the concept is aimed at proving that 220 knots is a sweet spot where speed is economically profitable.