The partners have collectively introduced a new kind of fuselage component, constructed entirely from carbon-fibre-reinforced thermoplastic (LM_PAEK). This novel material makes the fuselage component both less susceptible to damage and approximately one tonne lighter than an equivalent aluminium counterpart. Simultaneously, the team has pioneered production and assembly technologies that ensure cost-effectiveness and minimize energy consumption.

DLR manufactured a prototype, referred to as the Multifunctional Fuselage Demonstrator (MFFD), in Augsburg. The MFFD, a fuselage half-shell or the upper half of an aircraft fuselage, was built as a part of the Large Passenger Aircraft Programme within the European Clean Sky 2 research initiative. The primary objective is to decrease aircraft fuselage weight by 10 percent and operational costs by 20 percent, aiming at a production rate of 60 to 100 aircraft per month.

"By the middle of this century, the efficiency of current aircraft must be doubled to achieve climate-friendly flight. Lightweight system construction is one such approach," says Markus Fischer, DLR's Divisional Board Member for Aeronautics. "The upper fuselage shell made of fibre-reinforced thermoplastics, now manufactured at DLR in Augsburg, represents an unprecedented and promising milestone in this regard."

Thermoplastic Carbon-Fibre-Reinforced Polymers (CFRP) are distinctive materials that retain their shape when cooled but can be reshaped within a specific temperature range upon reheating. This unique property enables easier repair and more effective recycling of components than before. These advancements, brought to maturity by the research team, include laser-based in-situ fibre placement, continuous ultrasonic welding, and electrical resistance welding.

DLR used a robot to produce the aircraft's outer skin, applying laser-heated strips of material in layers to create a laminate of fibre-reinforced plastics. Subsequent curing, traditionally required for carbon-reinforced composites, is eliminated, which reduces production time by up to 40 percent and thus lowers costs further.

The outer skin was then fitted with longitudinal stiffeners. Instead of using traditional riveting techniques, the stiffeners were ultrasonically welded onto the component - a world first. Furthermore, the researchers developed an electrical resistance welding process for the installation of transverse stiffeners. This method yielded high weld strengths and allowed for a dust-free and hole-free load-bearing aircraft skin, significantly reducing production time and manufacturing costs.

The DLR team in Augsburg further advanced the resistance welding process to connect the longitudinal stiffeners to the crossmembers. This highly detailed work in tight spaces necessitated the use of a small lightweight robot, which accurately and quickly welded the dozens of connecting elements.

"The work on the MFFD upper shell was a highly challenging project, but the potential alternatives to decades-old technologies in aeronautics that we have developed are very promising," says Frederic Fischer, DLR Project Manager at the Center for Lightweight Production Technology (ZLP). "I am confident that lightweight construction will become even more important for future air transport."

The successful production of the world's largest aircraft component made of fibre-reinforced thermoplastics illustrates the maturity and low ecological footprint of the technologies developed during the MFFD project. DLR's work paves the way for the next generation of aircraft, enhancing competitiveness at regional, national, and European levels.

The fuselage half-shell has been at the facilities of project partner Premium AEROTEC since mid-June for the final stages of finishing and door frame installation. After successful delivery, the component is being transported to the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) in Stade.

Here, it will be combined with a lower shell from the Netherlands (STUNNING project) to form a complete fuselage shell section by the end of the year. Airbus will perform the final validation and verification of the technologies at the Center of Applied Aeronautical Research (ZAL) in Hamburg.

Related Links
DLR Center for Lightweight Production Technology
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