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Most UAVs have been developed as incredibly simple platforms, relying on old, simplistic flight models to lift sensor packages in the air. How they fly has been largely irrelevant, so much so that balloons have been considered and deployed for some applications.
But as number of missions UAVs are tasked to complete increases, engineers are looking at more complex platforms mirroring the evolution of piloted aircraft.
The ILA Berlin Air Show is inundated with UAV models, including one model that takes the concept of a tiltrotor and applies it to a UAV.
The AVIGLE tiltwing UAV, designed by the Institute of Flight System Dynamics at RWTH Aachen University in Germany, was designed as a solution to allow for deployment without a runway and the ability to hover over a target, while taking advantage of increased range and speed of a standard wing orientation. The system weighs only 10.5 kg, a lightweight demonstrator of a concept that could be scaled up.
But just as the Bell Boeing V-22, the manned tiltrotor aircraft used by the US Marine Corps, had its growing pains, so has the AVIGLE. In some cases the team has had to reinvent the wheel.
The university lost a UAV during early testing, but has since ironed out many of the kinks, said Dieter Moormann, who runs the program.
“There’s complexity because you only have one aircraft but three flight configurations,” he said. “The transition is the most difficult part.”
That moment when the aircraft switches from a hover to forward flight creates all kinds of complications, not the least of which being that the control surfaces that function effectively once the aircraft gets up to speed are fairly useless without much airflow. To fix that problem the team added what Moormann called an “impeller,” a push-prop midway down the body, that could help stabilize the craft during the transition.
The team also worked to automate various flight activities to make the platform more functional beyond line of sight. Some of that work to automate was necessary just to keep the aircraft in the air because of the complexity of the aerodynamics.
“It’s not possible for a human being to control all the surfaces, so you need a high level of automation,” Moormann said.
He said that the team hadn’t originally intended to create a tiltwing aircraft, but as the project got off the ground they realized that the requirements the team had for the system could only be completed with such a system.
“We needed to have high endurance, efficiency, and we needed to be independent of infrastructure,” Moormann said.
It’s just another sign that UAVs are moving beyond the simple mission of getting a payload in the air, and becoming a more potential backbone of future strategy. ■