Eurocopter Tests the X-Cube a New High-speed Hybrid Helicopter - Defense-Update
A Hybrid High Speed Helicopter (H3) technology demonstrator developed by Eurocopter began flight testing on September 6, 2010 at the French flight test center at Istres. The new aircraft designated ‘X3′ (X Cube) combines vertical takeoff, landing and hovering performance with high speed cruising capability at speeds exceeding 220 knots. The X3 demonstrator is powered by two turboshaft engines driving a five-blade main rotor system and two propellers installed on short-span stub wings. This configuration combines the speed of a turboprop-powered aircraft and the full hover flight capabilities of a helicopter.
The X3 high speed hybrid helicopter from Eurocopter (Photo: Eurocpoter)
The new concept could be utilized for missions where speed is a determining factor – such as military special operations, long range, long endurance search and rescue, medical evacuation, maritime patrol and border security, passenger transport and inter-city shuttle services.
Initial testing will continue through December with reduced power, progressively opening the flight envelope to speeds of approximately 180 kts. After a three-month upgrade, X3 flights will resume in March 2011 with the goal of reaching sustained cruise speeds in excess of 220 kts.
According to Lutz Bertling, Eurocopter’s President & CEO, the development of the X3 from concept to first flight took less than three years. The X-Cube concept was launched in January 2008, with aim to validate the technical concept of this high speed, hybrid proplusion VTOL system. While the X-Cube takes off and lands like a normal helicopter, during cruising the rotor RPM is reduced, in order to devoid the drag divergence at the tip of the advancing blade. The small wings added to the aircraft partially unload the rotor at high speed, and help avoiding the retreating blade stall. Wing mounted propellers provide the propulsive force in forward flight and anti-torque in hover, thus making the fenestron rotor tail redundant. The development team used elements from several Eurocopter helicopters for the X3, including an AS-365 airframe, the main rotor of an EC-155 and a main gearbox from an EC-175.