To make the profile adaptive, the demonstration wing’s trailing edge is fitted with three flaps. Each flap has four multifunctional trailing edges, or tabs, that can change position very quickly. Like a bird’s wing, the demonstrator’s wing will adapt to flight conditions—altitude, speed and aircraft weight. The flaps can retract to modify the chord, and the tabs can move to alter camber.
The aspect ratio on the converted Citation VII’s wing exceeds 15 (an increase from approximately 10 on an A320). The test wing spans approximately 20 m (66 ft.), including the 2-m movable tip sections. The design is representative of a commercial single-aisle aircraft at a one-third scale factor. Airbus UpNext tested a one-fourth-scale aerodynamic model in a low-speed wind tunnel at Airbus’ site in Filton, England, earlier in the project.
Aerotec & Concept, a specialist in business aircraft conversion, is in charge of carrying out the modification design. In June, Aerotec & Concept had installed most of the wing, overcoming the challenge of relatively unknown construction at the fuselage-wing interface on a non-Airbus aircraft. The modification includes metal transition boxes, measuring 1 m in span, on each side of the fuselage to link the root area with the composite wing. Each transition box also accommodates an attachment for the main landing gear. In addition, the box serves as a fuel tank because the composite wing does not carry fuel.
“Since June, we have installed the folding part of the wing and accompanying actuators at the interface,” Sébastien Blanc, X-Wing technical director, says. Technicians also reinstalled the engines, which the two companies had removed to protect them from the dust-generating process of cutting out the original wing. More recently, engineers have performed a power-on test and are now evaluating the wiring and interconnection system.
The replacement of the conventional flight control system took several months, and testing began Sept. 10. Airbus UpNext wants the control system to be representative of Airbus commercial aircraft, so the company decided to install fly-by-wire technology. Technicians are equipping the Citation with computers and local electric actuators. “Every control surface, including in the empennage, will be fly-by-wire,” Franck Delaplace, X-Wing demonstrator leader, says.
In parallel, the aircraft is receiving sensors dedicated to the test campaign. Videogrammetry—the use of video to measure how distances change between target objects—will contribute to various measurements. The X-Wing project will assess wing deformation, especially the movement of control surfaces, such as ailerons and spoilers. The technique relies on black circular markers on an easy-to-install stippled rendering.
To keep down costs of safety requirements, the aircraft is designed to fly uncrewed. Flight-test pilots will control the aircraft remotely from the ground, allowing Airbus UpNext to test the new technologies to their limits.
Technicians are removing the control columns and installing a remote control system, in addition to replacing the transparent windshield with a metallic one. In the cockpit, a lidar sensor will enable the aircraft to “see” turbulence 0.5-1 sec. ahead and move the control surfaces accordingly. “We already tested the dedicated communication system for remote control,” Blanc adds.
Airbus has applied to French civil aviation authority DGAC for a permit to fly. The demonstrator will take off from Cazaux, in the southwest of France, and fly over the Bay of Biscay.
Airbus UpNext plans to submit the aircraft to ground vibration testing also this year. Wing-loading trials—less severe than in certification tests—are planned to follow by year-end. “The idea is just to correlate test measurements with models,” Blanc says.
Taxi tests are scheduled for the second quarter of 2026, and the first flight is expected in mid-2026. “We can use the demonstrator until the end of 2026, and we intend to fly as many hours as possible by then,” Blanc says.