The Eurocopter X3 is an experimental high-speed hybrid helicopter under development by the French aviation Company Eurocopter.
The Eurocopter X3 hybrid helicopter has opened the frontiers of aviation by attaining a speed milestone of 255 knots (472 km/hr) in level flight on June 7. Several days before this accomplishment, the X3 reached a speed of 263 knots (487 km/hr) during a descent. With these two successes, the X3 surpasses the unofficial speed record for a helicopter. Source: Article
