Eurocopter has entirely opened the flight envelope of its X3 compound helicopter (F-ZXXX), Jean-Michel Billig, Eurocopter executive vice president for research and development director, told AIN last week at the Helitech show in Duxford, UK. Recent work has focused on finalizing control laws for the unusual rotorcraft’s trims and fine-tuning the settable parts on the wing stubs, which have no movable parts. This work will help yield the definitive aircraft attitude, Billig explained. “By year-end, we will fly at full power,” he added. When the X3 reached 232 knots last spring, its power setting was at about 75 to 80 percent. In addition to flying fast, F-ZXXX has demonstrated a rate of climb greater than 5,000 fpm and turns at 80 degrees of bank angle. A modified AS365 Dauphin with a conventional main rotor, two propellers on wingstubs and a conventional empennage, the X3 is targeted at demonstrating that 220 knots is an economical sweet spot for such a helicopter. The X3 demonstration program will cease at the end of the year, Eurocopter said.