Eurocopter X3

Eurocopter began a X3 flight testing programme in September 2010 that combines the vertical takeoff and landing capabilities of a helicopter with an aircraft's fast cruise speeds of more than 220 kts. After achieving the initial true airspeed goal of 180 kt (333 km/hr) in November 2010 at a reduced level of engine power, the X3 underwent its planned gearbox upgrade and safety inspection. Since returning to flight, the X3 quickly demonstrated its performance at full engine power, including impressive climb and descent rates as well as manoeuvrability while also confirming the hybrid propulsion system's capabilities for acceleration and deceleration.
The hybrid aircraft has low vibration levels without the use of passive or active anti-vibration systems, providing flight characteristics comparable to those of the best traditional design helicopters currently in service.
Eurocopter's X3 hybrid helicopter demonstrator had an original speed target of 220 kts, The X3's speed milestone was reached on 12 May 2011 during stable level flight; the hybrid demonstrator maintaining a true airspeed of 232 kts (430 km/hr) for several minutes. This occurred during only the third mission after a scheduled upgrade that integrated the X3's definitive gearboxes, enabling it to operate at full power.