The SWING Project, funded by the European Union, has announced that it has developed and manufactured a new lightweight Krueger flap using laser welding. These flaps, typically located at the leading edge of the wing and retracted by actuators, help the aircraft achieve better laminar flow control, thereby increasing lift in flight.
Laminar flow refers to the way air flows over and under the wing and is determined by the friction (drag) between the air and the wing. Engineers want to reduce this airflow as much as possible, because drag both affects flight performance and increases carbon emissions.
Krueger flaps are able to better control the antilaminar flow and act as "deflecting plates" when stretched in position, deflecting insects away from wings that could disrupt laminar flow.
The consortium designed a new Krueger flap between October 2019 and September 2022 using lightweight, recyclable composite materials. Partners in the alliance include: AFPT, Loiretech Holding, ETIM and Cetim Nantes (industrial technology centre Mecaniques).
Alliance partners achieved a "flap" design with complex geometry by laser welding thin thermoplastic composite prepreg strips. The use of robots with laser heads to reinforce parts in situ avoids additional process while providing higher reliability, repeatability, and improved overall part quality.
Compared with current industrial manufacturing methods, the new design and optimized manufacturing methods not only increase the speed of raw material laying, but also are expected to reduce the manufacturing cost of Kruger flaps.
Christophe Cornu, research project manager at Cetim Nantes and SWING project coordinator, said: "The objective of the project was to verify its (new design) industrial feasibility, which means its manufacturability, and we have reached the required level of technological maturity. The main advantage of thermoplastic polymer materials over other materials is their recyclability. In addition, the processing of thermoplastic materials requires less additional manipulation, so its cost may be reduced in the future when the technology is fully developed."
It was revealed that the part has now reached Technical readiness Level 4 (TRL 4) and the wing design and manufacturing process is currently undergoing ground functional testing for validation in the coming years.
