Aeroelastically tailored wings

It was the first in the world to fly in a real environment towards the end of last year, a so-called aeroelastically tailored wing aircraft in which the wind direction of the carbon fiber composite changes along the wing.

The purpose of testing the aircraft, developed in an international project called FLEXOP, was to investigate the passive damping of the load on the wings. In addition to leading the project, SZTAKI designed, built and operated the on-board avionics (electric and electronic flight) system, including in-flight sensors and actuators, as well as the software and hardware components of the on-board autopilot system to perform repeatable experiments and collect data.

“The strenuous work of the last four years is crowned by the fact that during flight tests we obtain valuable data on the behavior of the aircraft, thus proving the research results of the partners. Thanks to the outstanding operation of the on-board data collection system built by SZTAKI, we are also able to document the results achieved in the project excellently, ”says Bálint Vanek, Head of the Flight Control and Navigation Research Group at SZTAKI (Computer and Automation Research Institute).

20 minutes flight = 10 gigabytes of data

The test aircraft had already taken to the air several times, but at that time the pilots were only controlled by a radio remote control. On the current flight, the autopilot has also been switched on, which is also important for scientific experiments: it implements special, research maneuvers in a repeatable way, much more precisely than manual control. This, in turn, is necessary to compare the traditional composite wings that are common today with the lighter and more flexible wing built into the project. Thanks to the special, guided cut pattern of the carbon fibers in the wing of the experimental aircraft, the wing is strong from whatever direction, while the rest of the material can save weight, and since the new generation wing has lower forces for the same flight maneuvers, the flight can be greener and cheaper. Because the aircraft is 65 kilograms and has a wingspan of 7 meters, it is subject to much stricter regulations than a drone under 25 kilograms. The flights needed to answer the research questions are planned very precisely in advance, and the flights are practiced in advance on a simulator by the team of the Technische Universität München (TUM), which also performs live tests.

The flight took place at Oberpfaffenhofen (EDMO) airport near Munich, in addition to normal civilian passenger traffic. The ground control center of the flexible-wing test aircraft therefore communicates not only with the two pilots in flight, but also with the airport tower. In flight, the pilot performs the maneuvers he receives from the flight test operator through his headset. Meanwhile, the co-pilot continuously monitors his first movements to intervene in the event of an emergency. Because the airspace provided to the test aircraft is limited (2 × 0.5 kilometers), the ground control center helps the pilot not to leave the airspace. During flight, the behavior of the on-board systems and the data collected are monitored in real time by the on-board systems engineer: during the 20-minute test flights, 8-10 gigabytes of flight data are generated, analyzed by the partners after the flights, used to verify theoretical results and to refine its model. Airbus is also a member of the project, which wants to apply the results achieved here to the design of civil aircraft.