# Experimental Validation and Evaluation of a Coupled Twist-Camber Morphing Wing Concept
## 1 Introduction  
The idea of changing the geometry of the lifting surfaces to adapt them to the flight condition is not new. Flaps and slats are examples of such changes but they are used for short flight segments due to their specific usage for take-off and landing. Morphing aircraft also follow the same idea and have been researched for more than a decade, with the main goal of improving overall flight performance. The metric usually used for assessment is fuel consumption. The challenges presented in shape adaptation remain unanswered due to the opposing requirements of flexibility and sufficient stiffness and load-bearing capability. The usual consequences of these challenges are the potential aerodynamic benefits being overweighed by extra mass or energy penalties. Methods for the design and modeling of morphing wings can be found in [1]. Investigations on flutter suppression in a variable span morphing wing were performed in order to determine its applicability and morphing speed in relation to the critical span length [2]. Low fidelity models were used to assess flutter instability in a camber morphing wing. Quasi-steady aerodynamics and unsteady aerodynamics were used with the quasi-steady model showing more conservative results and active camber morphing could be used for stabilization of the wing [3]. Still, within the camber morphing research, aero-structural high-fidelity optimization of an adaptive trailing edge for transonic flight predicts decreased fuel burn by more than 5% [4]. Optimum deformations for a transonic airfoil with morphing leading and trailingedges were obtained using high-fidelity aero-structural modeling, showing significant aerodynamic performance improvement [5]. Compliant leading and trailing edge mechanism design considering nonlinear large deformation based on hyper elastic structural topology optimization with a non-linear meshless method have been performed. A demonstrator was built to assess deformation capability and aerodynamic benefits [6]. Morphing droop nose devices for the high lift in regional aircraft were developed [7] and designed up to a detailed CAD model to assess functionality, installation, inspection, actuation power, and weight [8]. An adaptive shock control review on a number of shock control bumps concepts for wave drag reduction that includes conventional spoiler actuators, shape memory alloys, or pressurized elements is another type of morphing concept [9]. An example of a bioinspired morphing concept based on artificial feathers for small drones was investigated using simulation, wind tunnel measurements, and outdoor flights [10]. Composite lattice-based cellular structures have been proposed to tailor the stiffness of a structure with low-density modular building blocks and demonstrated with a variable twist wing [11]. Corrugated morphing skins were proposed to tackle the problem of shape change and aerodynamic load-bearing capability [12]. Morphing wing twist capability together with camber change capability in the horizontal stabilizer proved to be effective in achieving roll control and lift changes in a small unmanned aerial vehicle (UAV) [13]. Wing twist morphing capability also promises performance improvements in transport-type aircraft [14] and combat UAVs [15]. Investigations on the importance of morphing scheduling and flight condition on the actuation force and energy requirements show that these factors can be determinants of the assessment of the viability of a morphing device [16]. Not only have independent groups been investigating morphing aircraft technologies but it has also been a research field supported by collaborative research programs. The NOVEMOR project addressed novel aircraft configurations and morphing solutions for improved flight performance in the conceptual design stage [17]. The SARISTU project addressed the challenges in integrating smart and intelligent structures in commercial aircraft [18; 19].