|X3 prototype. Eurocopter
During the Paris Air Show in June, Eurocopter CEO Lutz Bertling said that the AS365/EC155 Dauphin medium twin replacement program, code named X4, is now fully launched. In an unusual arrangement, two versions are planned to enter the market successively. The other X factor in Eurocopter’s projects, the X3 (“X Cube”), was a highlight of the flying display; its applications are promised to market success in the offshore and commuter segments, according to Bertling.
In 2016, the first X4 will use technologies that are today at technology readiness level (TRL) 6, meaning they have been ground tested. Then, in 2020, a second version will feature systems that are now much more at a feasibility stage—TRL 2. This upgraded X4 will “completely change the way of flying,” Bertling said. He asserted that a pilot would not recognize the cockpit and its controls. Indeed, an artist rendering of the cockpit, copyrighted by Eurocopter but released by equipment and engine manufacturer Safran (and with no mention of whether it is the X4’s first or second iteration), shows a radical departure from what we are used to (see the rendering at www.rotorandwing.com). The way information is displayed is just as different from today’s glass cockpits as they are from classic clock-and-gauge arrangements. The windshield seems to be the primary flight display, with a highway-in-the-sky-type depiction of the flightpath. A relatively conventional display, in the center, holds navigation maps and engine parameters. An additional display (likely to be a touchscreen) is located between the pilots, on the pedestal. Sidesticks clearly indicate that the flight controls use a fly-by-wire system, probably made by Sagem. Eurocopter and Sagem have been working on fly-by-wire controls for a long time for the NH90 military transport. For at least four years, Eurocopter also has studied use on civil applications. The remaining challenges are weight and cost, Bertling admitted.
From the exterior, the X4 looks like a sleeker successor of the EC155/AS365, with large transparent surfaces. It keeps Eurocopter’s signature shrouded tailrotor, the Fenestron. The main rotor uses Blue Edge, a double-swept blade that Eurocopter has been evaluating for some time but only unveiled in 2010. The idea is to reduce blade-vortex interaction and thus, noise.
On the engine side, Turbomeca is working on the TM800, in the 1,100-shp class. The turboshaft company is planning on a 20 percent cut in fuel consumption. The TM800 is to replace the Arriel 2 family and the TM333. The first component rig tests should take place by the end of 2011.
The X4 may be Eurocopter’s newest program but the company’s main attraction in Paris was a demonstrator—the X3. The compound helicopter is a modified AS365 Dauphin with a conventional main rotor, two propellers on wingstubs and a conventional empennage. While helicopters usually fly at 140-150 knots in cruise, the concept is aimed at proving that 220 knots is a sweet spot where speed is profitable. It was unveiled in September 2010 at Istres’ military flight-test center in France, near the helicopter manufacturer’s factory in Marignane. Since then, Eurocopter officials have several times hinted that the first application of the concept will be for offshore oil and gas operations. At the show, Bertling added that it will likely be in the 12- to 19-seat category. Program launch may take place next year (2012) or even by the end of this year. But the next application may be a 30-plus-seat commuter. “In future, airports will face severe slot scarcity; a vertical takeoff and landing aircraft does not use the runway and thus, needs no slot,” Bertling asserted. Therefore, “a lot of commuting services will go vertical.” In the 2020s, it will be time to develop such a big module, he said.
Bertling admitted that Eurocopter shares this vision with AgustaWestland. The latter, however, is developing a tiltrotor, the AW609, rather than a compound. Bertling finds the tiltrotor architecture too expensive. Except if “one day, it could be an all-electric aircraft, because you would save the gearboxes,” he suggested. Bertling expects the price premium for the X3 concept to be about 25 percent, while the operating cost per passenger-mile would be 20 percent lower than that of a conventional helicopter.
During the second flight-test campaign, which started in May, the X3 demonstrated a rate of climb greater than 5,000 feet per minute. The crew flew pitch-up attitudes in the 30- to 50-degree range. Turns were performed at 80 degrees of bank angle. A true airspeed of 232 knots was sustained during approximately five minutes at 8,200 feet on May 12. Further flights this year will dig deeper into vibration phenomena and wingstub aerodynamics.