The Eurocopter X3 has set an unofficial helicopter world speed record of 255 knots in level flight, slightly faster than the 250-knot top speed achieved by the Sikorsky X2 compound helicopter in 2010. Eurocopter said the hybrid X3 also reached a speed of 263 knots in a shallow dive, three knots faster than the X2 managed. Once the flight results are confirmed, the X3 would be named the fastest helicopter ever.
Eurocopter hit the historic speed milestones on June 7 at an altitude of around 10,000 feet over southern France near Istres. The X3 is able to achieve such remarkable speed by the use of a slowed main rotor and two forward-facing propellers that together overcome the physical challenge of retreating rotor blade stall common to all helicopters. The fastest traditional helicopters are typically limited to top speeds of around 175 knots.
