FEATURE “Aeronautics” A double-curved, 7-mlong torsion box demonstrator product is being developed as part of the TAPAS project. It will be built and tested in 2011. The product is a redesign of the central portion of the Gulfstream 650 horizontal tail (Fig. 15). Its skin will feature integrally butt joined T-stiffeners. g…/… New thermoplastic composite design concepts and their automated manufacture Fig. 12: Butt jointed sine wave beam placement cell with a single 10 mm-wide strip was built by Dutch aeronautics specialist Boikon. The UD strips were melted over a small portion of strip width, enough to affix the tape. With ultrasonic fibre placement, the challenge was to succeed in tacking a tape onto an underlying thick stack of plies at high speed, without slowing down the process and thus making it ineffective. A new fixed wing leading edge concept was laid up with the fibre placement cell (Fig. 12). The product development process, which started as an internal Fokker product improvement exercise, is now a part of a European Framework project called COALESCE (Cost Efficient Advanced Leading Edge Structure). Fig. 15: TAPAS skin with integrated stiffeners drawn over full-size horizontal tail Research is ongoing to determine if out-of-autoclave manufacturing is feasible. Fibre placement is the preferred layup technology for minimizing material waste during the layup process. A dedicated fibre placement cell will be used for skin layup. The cell will be programmed with CGTech’s Vericut Composite Programming module, which links the CATIA design to the robot software. The cell can be expanded at modest investment for series production of 12-m full-span skin panels (Fig. 16). Fig. 13: Flat rib preforms The new leading edge is a multi-rib thin skin design. The ribs are flat plate preforms (Fig. 13) which are butt joined to the skin during melting (co-consolidation) of the product. The skin is fibre placed over a positive tool (Fig. 12). Two parts are manufactured simultaneously. The layup is covered by a caul plate, vacuum bagged and co-consolidated. One of the two resulting parts is shown in Figure 14. 7-m torsion box demonstrator Fig. 14: Co-consolidated wing leading edge product Fig. 16: Fibre placement R&D cell and production cell This equipment approach is typical of the current trend towards part-centred aeronautics. A machine is tailored to the product concerned: size and shape, layup and build rate. The required material lay-down rates are achieved at 48 jec composites magazine / No58 June - July 2010