## 1 Introduction  
Currently, the aviation industry is developing quieter and more efficient aircraft to reach the environmental goals of Flightpath 2050 [1, 2]. New technologies are expected to allow a 75% reduction in CO2 emissions per passenger kilometre and a 90% reduction in NOx emissions. The perceived noise emission of flying aircraft is to be reduced by 65% [3]. The investigation and development of new high-lift devices provide not only an improvement of aerodynamics, but also a positive effect on the emission of noise and pollutants. Over the last years, the volume of air traffic has increased approx. 5% per annum. This means that air traffic will considerably increase within the next 20 years. In order to sustain the CO2 and noise emissions, they have to be significantly reduced. Traditional high-lift devices, such as Krueger flaps or slats, provide an increase of the aerodynamic lift, but also an increase of the noise emission [4, 5]. This increase in noise is due to the presence of a gap between the high-lift device and the main wing [6]. If a gapless high lift device can be designed, this source of noise emission vanishes, which may in turn reduce the noise footprint of the aircraft. One way forward is the development of gapless, morphing high-lift devices. Additionally, gapless, morphing high-lift devicescould be an enabl for natural laminar flow (NLF) [7, 8]. Therefore, for several decades, the aviation industry, as well as research institutions, have been investigating morphing high-lift devices. Some examples are briefly described below. [PERSON] and co-workers experimentally and numerically demonstrated that morphing leading edge concepts can potentially replace traditional leading-edge devices in terms of their aerodynamic properties [9]. However, for the design of a morphing leading edge, the aerodynamic efficiency is not solely important. The MLE designed here was intended to be placed on an unmanned aerial vehicle (UAV). For this slow-flying UAV, the polymer skin was designed in a way that it did not contribute to the load carrying capability of the wing. However, for larger aircraft operating at higher velocities, the structural aspects of the skin, and in particular the fluid-structure interaction, should not be forgotten [8]. Within the scope of the European project \"Smart high lift devices for next generation wings\" (SADE) between 2008 and 2012 diverse concepts for deformable leading and trailing edge were considered. For the leading edge, approaches with aeroelastic effects, selective deformable structures with frames, as well as innovative actuator concepts were investigated [10]. Within SADE, [PERSON] tried to design a MLE with a carbon fibre reinforced composite skin for an A320 type aircraft. However, Finite Element simulations showed that the particular stacking sequences selected in the Cranfield design were not capable of withstanding the high aerodynamic loads imposed on the MLE. Therefore, the skin material was changed to aluminium [5]. [PERSON] and co-workers developed a small-scale morphing leading edge demonstrator featuring a carbon fibre reinforced composite (CFRP) skin with stacking sequence \([+10/-10]_{\text{ns}}\). The actuation concept makes use of filament-wound rubber muscles [11]. The German Aerospace Centre (DLR) has been investigating adaptive structures for several years, where the focal point is research on a suitable skin to reach the requested deformation. Within the project \"Smart Leading Edge Device\" (SmartLED), DLR realised a concept for a gapless leading edge in a 1:1 scale demonstrator. Glass fibre material with varied thickness of the laminate (ply drop-off) was used in conjunction with omega stringers, and an actuation kinematic was designed [10]. Within the framework of the \"Smart Fixed Wing\" platform of the European research programme \"Clean Sky\", DLR developed flexible morphing skins composed of glass fibre-reinforced composite and a layer of elastomer [12].