Eurocopter X³
The Eurocopter X³ (X-Cubed) is a retired experimental high-speed compound helicopter developed by Airbus Helicopters (formerly Eurocopter). A technology demonstration platform for "high-speed, long-range hybrid helicopter" or H³ concept, the X³ achieved 255 knots (472 km/h; 293 mph) in level flight on 7 June 2013, setting an unofficial helicopter speed record.