New technologies and materials are accelerating the rethinking of aircraft structure production.
It is suspended between scattered component fixtures and does not attract second glance on the aircraft assembly line. However, in an anonymous hangar in northern Germany, a matte black fuselage section – or cylinder in jargon – could be the super-efficient shape of the future.
Clean Sky 2 is an ambitious, EU-backed public-private partnership with the overall goal of reducing aircraft CO2, NOx and noise emissions by 30% in line with the European Green Deal. The stated goal of the agreement is to make the EU climate-neutral by 2050.
The black cylinder was developed in 2014 and belongs to the Multifunctional Fuselage Demonstrator (MFFD) as a sub-project of Clean Sky 2. It is 8 meters long and 4 meters wide and is mainly made of thermoplastic composites. By studying the feasibility of these polymers as structural materials, MFFD effectively serves as a springboard to accelerate aircraft production, thereby increasing the competitiveness of European aerospace.
The body is lighter and faster
The fuselage does more than just accommodate passengers and cargo. It also carries important electrical, mechanical, pneumatic, and hydraulic systems. Installing the system after the completion of the airframe increases production costs and time. The system is also heavy. Lighter, easier-to-produce thermoplastic composite airframes help counteract these drawbacks.
Thermoplastic composites make this possible, mainly because the large number of fasteners that join traditional metal body parts together is no longer required, or the number required is much smaller.
Thermoplastic composites stand for Carbon Fiber Reinforced Thermoplastic Polymer Composites (CFRTP), which can be molded at high temperatures. It is then cooled and cured. If the typical fuselage segment is skillfully combined with cabin and cargo hold parts, their introduction could result in structural weight savings of more than 10% per aircraft.
CFRTP composites also offer a more immediate advantage: they are easier to reuse and recycle than metal or carbon fiber parts.
Pre-installed modules
Back to our storeroom. The MFFD consists of two semi-cylindrical shells or modules, which make up the fuselage barrel. The lower module is pre-equipped with the system and wiring; There are some cockpit logos on it.
On the pure production side, thermoplastic composites enable the modules to be assembled using new methods, each of which is tested on MFFD. For example, its housings are connected by automated ultrasonic or laser spot welding, rather than riveted together. This creates a relatively dust-free environment for assembly workers. The floor of the lower fuselage model is then fixed in place by automatic conduction welding.
By the end of 2024, the MFFD has actually exceeded its weight reduction target, and its cost is neutral compared to the metal body barrel. More than 40 technical "specializations" have been tested at a high level, ranging from small micromechanics (the study of the behavior of composite materials) to new fixtures, tools, and, as described above, advanced welding techniques.
MFFD's disruptive approach could enable the manufacturing rate of CFRTP composite airframes to reach 100 per month, which is the target rate for future single-aisle aircraft. In addition to economic benefits, the new body's advanced architecture, lower weight, and higher manufacturing rates will help reduce lifecycle emissions, in line with Clean Sky 2's goals.
A success story in Europe
Since its completion, the demonstrator has been residing at the ZAL Center for Applied Aviation Research in Hamburg. It was actually assembled at the Fraunhofer Institute near Stad. Airbus has extensive facilities in both cities in Germany.
MFFD's innovation is a completely European success story. Airbus is one of the 13 main partners that make up the consortium, including Saab, GKN Fokk, the Germany aerospace laboratory DLR, Delft University of Technology and a subcontractor.
"If academia, research centers and industry players are united around a common goal, the MFFD is a good example," said York Roth, head of Airbus' Clean Sky 2 large passenger aircraft platform. "A single player will never be able to deliver such a complex and large demo body."
原文，《Fantastic thermoplastics 》 2024.10.15
Chaofan Yang 2024.10.16