According to a report from Flightglobal, Airbus will soon start flight testing an A340 that has been fitted with experimental laminar-flow wing sections. The effort is part of a larger EU-funded technology project, dubbed the Breakthrough Laminar Aircraft Demonstrator in Europe (BLADE), to assess the industrial feasibility of natural laminar-flow wings on future aircraft. The BLADE project represents the largest part of Airbus’s estimated €330 million ($392 million) contribution to the EU’s current Clean Sky II initiative – a multi-year program that includes other projects to advance technology for more efficient aircraft engines, helicopters and onboard systems.
Many modern aircraft, including the Boeing Dreamliner, feature hybrid laminar flow wings, which are artificially induced through hardware. According to Axel Flaig, senior vice president of research and technology for Airbus’s commercial aircraft division, the benefits of laminar airflow have been known for 20 years but have never been practically applied. He says that is because it hasn’t been possible to produce on industrial scale wings that are smooth enough to achieve a laminar airflow and aerodynamically robust enough to achieve the desired effect in daily airline operations.
For laminar profiles, it is important that they are extremely smooth with precisely finished surfaces. This means building wings without rivets or other factors that could disrupt the airflow. This reduces fuel consumption and CO2 emissions.
Airbus has replaced the entire wing section of the A340 outside the outboard engines with a laminar-flow section that has a different geometry. The wingtips have been fitted with pods containing sensors and video cameras. The attachment structure to the A340’s existing wing has also been covered by fairings to accommodate further sensors and separate the air over the laminar-flow section from that across the conventional wing.
The new wing section contains no fuel system, but is otherwise fully functional and includes the aircraft’s two ailerons on each side. The interior structure is metallic, while the upper wing surface – where laminar flow is to be achieved – is made from CFRP. Different construction techniques were employed for the leading edge and upper wing skin to assess the feasibility of different manufacturing approaches. On the port wing, the leading edge is integrated with the upper wing surface in a single D-nose carbon fiber panel, provided by Saab, which is equipped with internal attachment points to avoid any external fasteners from the leading edge to just forward of the ailerons. On the starboard side, a metallic leading edge is joined with a carbon fiber upper wing surface supplied by GKN Aerospace.