EADS Global Website - Hybrid Helicopter

At Eurocopter, increasing the mobility of rotary-wing aircraft is the object of an innovative hybrid platform called the X3, which flew for the first time in September 2010 and surpassed the speed of a traditional helicopter just two months later. Based on a Eurocopter Dauphin helicopter airframe, the X3 demonstrator is equipped with two turboshaft engines that power a five-blade main rotor system and two variable-pitch propellers installed on short-span fixed wings. While this hybrid configuration may be more mechanically complex than a conventional helicopter, it is much simpler than other higher-speed designs, such as tilt-rotor aircraft.

The hybrid concept offers the speed of a turboprop-powered aircraft and the full hover flight capabilities of a helicopter, with its use tailored to applications where operational costs, flight duration and mission success depend directly on the maximum cruising speed. Eurocopter foresees a wide range of missions for the helicopter, including long-distance search and rescue (SAR), coast guard duties, border patrol, passenger transportation and inter-city shuttle services. Additionally, it also could be well-tailored for military missions in special forces operations, troop transportation, combat SAR and medical evacuation – benefitting from the hybrid aircraft’s combination of higher cruise speeds with excellent vertical take-off/landing performance.

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Everything was taken from parts already designed for other aircraft but modified to varying degrees for the X3: the N1 Dauphin provided the airframe; the EC155 gave the five-bladed rotor and the automatic pilot; the NH90 donated its turbines (2 x RTM322 of 1,693 kW); the EC175 the central module for the gearbox; and the trim actuator motors came from the EC145.

Breaking barriers

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In its initial months of flight testing at the Istres Flight Test Centre, in southern France, the X3 demonstrator reached an airspeed of 180 kts (333 km/h) in level flight – faster than today’s rotary-wing aircraft. This milestone was attained with the X3 using an initial gearbox configuration, which provided a reduced power output for the main rotor and propellers. The first flight evaluation phase also opened the flight envelope to validate the aircraft’s stability and handling characteristics, with the X3 climbing to an altitude of 12,500 feet and manoeuvres performed with bank angles of up to 60 degrees.