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Natural laminar flow is one of the challenging aims of the current aerospace research. Main reasons for the
aerodynamic transition from laminar into turbulent flow focusing on the airfoil-structure is the aerodynamic
shape and the surface roughness. The Institute of Composite Structures and Adaptive Systems at the German
Aerospace Center in Braunschweig works on the optimization of the aerodynamic-loaded structure of future
aircrafts in order to increase their efficiency. Providing wing structures suited for natural laminar flow is a step
towards this goal. Regarding natural laminar flow, the structural design of the leading edge of a wing is of special
interest. An approach for a gap-less leading edge was developed to provide a gap- and step-less high quality
surface suited for natural laminar flow and to reduce slat noise. In a national project the first generation of the
3D full scale demonstrator was successfully tested in 2010. The prototype consists of several new technologies,
opening up the issue of matching the long and challenging list of airworthiness requirements simultaneously.
Therefore the developed composite structure was intensively tested for further modifications according to meet
requirements for abrasion, impact and deicing basically. The former presented structure consists completely
of glass-fiber-prepreg (GFRP-prepreg). New functions required the addition of a new material-mix, which has
to fit into the manufacturing-chain of the composite structure. In addition the hybrid composites have to
withstand high loadings, high bending-induced strains (1%) and environmentally influenced aging. Moreover
hot-wet cycling tests are carried out for the basic GFRP-structure in order to simulate the long term behavior of
the material under extrem conditions. The presented paper shows results of four-points-bending-tests of the most
critical section of the morphing leading edge device. Different composite-hybrids are built up and processed. An
experimental based trend towards an optimized material design will be shown.
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