's X3 has claimed the unofficial helicopter speed record from 's X2, achieving 255 kt. in level flight and 263 kt. in a dive, and raising the question of what comes next for the European manufacturer's high-speed rotorcraft concept.
In flights at the Istres test base near Marseille, France, in early June the X3 experimental compound helicopter beat its previous top speed of 232 kt. set in May 2011. The new round of high-speed trials follows a lay-up during which the aircraft's gearbox was tweaked to operate at the full power level provided by its twoRTM322 turboshafts.
The X3 also was fitted with an aerodynamic fairing around the rotor head to reduce its parasitic drag. The company says test data related to installation of the fairing will be “beneficial for drag optimization across Eurocopter's overall product range.” The X3 has now flown a total of 140 hr. since its maiden flight in September 2010. The company is understood to be planning to retire the X3 toward the end of the year, the aircraft having generated more data on high-speed rotary-wing flight than was originally envisaged.
Sikorsky's rigid coaxial-rotor X2 technology demonstrator achieved 253 kt. in level flight and 262 kt. in a dive in September 2010. The aircraft was retired in July 2011 after logging 22 flight hours, and Sikorsky began development of the 220-kt. S-97 Raider light tactical helicopter. The first of two industry-funded prototypes is scheduled to fly at the end of 2014.
Subsequently, Sikorsky teamed withfor the U.S. Army's planned Future Vertical Lift Medium program to replace the Black Hawk beginning in the mid-2030s. The team has been selected to build a 230-kt. compound helicopter demonstrator based on the X2 configuration. The aircraft is planned to fly in 2017 under the Army's Joint Multi-Role (JMR) technology demonstration program.
Eurocopter was expected to propose an X3-configuration demonstrator for JMR, butwithdrew its bid to focus company resources on the Army's Armed Aerial Scout requirement (AW&ST June 10, p. 31). This raises the question of what the company has planned for the technology.
Eurocopter may now see the X3 as having wider applications in commercial and civilian government roles. Interestingly the company highlights civil missions over military applications, with long-distance search-and-rescue, offshore airlift and passenger transport, along with inter-city shuttle services, suggested as possible roles.
An X3-based compound helicopter called LifeCraft is one of two fast rotorcraft flight demonstrators planned under the Clean Sky 2 research program now being proposed to the European Commission. Planned to fly in 2018, the LifeCraft would have a 220-kt. cruise speed. High-level objectives for the program include demonstrating emergency evacuation over 200 km in less than 30 min., and gate-to-gate travel over 550 km in less than 90 min.
LifeCraft would have the same configuration as the X3, with twin turboshaft engines driving the main rotor and wing-tip variable-speed propellers via a single main transmission. This provides the agility of the helicopter while avoiding the need for a tail rotor and it enables high speed, with the propellers providing propulsion and the wing off-loading the rotor.
Before he retired from Eurocopter, then-CEO Lutz Bertling spoke of the company's vision of providing rotary-wing commuter aircraft which would remove the need for slot use at constrained international airports. He suggested that such an aircraft, perhaps with the X3 technology, could be available in the early 2020s.
It is likely any aircraft using the X3 design would be at the heavy end of the company's product range. The X6, which is understood to be a replacement candidate for the AS332 and EC225 Super Puma, is currently under development. It is possible the company may develop two versions of the helicopter, one conventional, the other using X3 technology.
“Helicopters can fly relatively fast and the noise footprint for people living around the airport is relatively similar to current traffic noise, so vertical lift can still play a role in commuting people, providing you can design an aircraft that delivers higher speed at reasonable cost,” said Bertling. Regional jets and turboprops will continue to have a place, however. Even though the X3 is faster than traditional helicopters, it is still not as fast as a turboprop.
“I believe we could well see the first serial products which could do the job with a smaller number of passengers—say 19 seats—at the beginning of the 2020s, and I could imagine seeing larger aircraft with 30-40 seats in the mid-'20s,” he said.
The current EC225/725 family continues to sell, but its design is based on the 1965-vintage Aerospatiale SA330 Puma. With the EC225 now losing market share to Sikorsky's newer S-92 and also the smallerAW189, the time for a new product may be right.