At the first stage, an aerodynamic optimization with structural constraints is performed for the definition of the optimal target shape according to the requirements. The developed design procedure is mainly based on a multilevel multidisciplinary optimization loop. In the last ten years, PoliMi has been involved in several projects, through which the authors have acquired an important background in the design techniques for morphing structures application. The approach here proposed for the design of this kind of morphing device is based on an internal compliant structure connected to a flexible composite material skin. Indeed, the design of morphing structures is a tough challenge due to the contemporary presence of conflicting requirements, such as a sufficient flexibility required to accomplish the shape change coupled with the typical load-bearing capability. The major challenge is the design of a structure able to guarantee the expected target shape, while satisfying the certification rules. The adoption of the morphing leading-edge device can ensure the desired high-lift performance, along with enhanced efficiency with respect to the baseline configuration, also considering that usually regional aircraft do not employ conventional slats.įrom the aerodynamic perspective, the design objective is the definition of the optimal drop law and shape for the achievement of the required performance. One of the developed devices is a morphing Droop Nose whose aim is to achieve the requested high-lift performance during take-off and landing and, at the same time, to preserve the optimal Natural Laminar Flow (NLF) wing shape in cruise.
In the framework of Clean Sky 2 REG–IADP AIRGREEN 2 (AG2) project, many morphing concepts are analysed to be applied to a next-generation twin-prop regional transport aircraft.
Moreover, the bird impact safety of the leading edge is demonstrated according to the certification rules.
Final verification on the virtual prototype assesses the functionality of the device when attached to the wing-box. All these requirements contribute to the definition of an advanced and complete solution for the device, up to the realization of a detailed CAD model. At the same time, various design aspects are evaluated, such as installation and inspection issues, actuation power, and weight considerations. Stress analyses on high-fidelity models of the single adaptive ribs are also performed.
A finite element model of the complete device is generated for the three-dimensional shape quality evaluation and for the skin structural verification.
The main aim is the achievement of a feasible solution based on the use of conventional materials, such as aluminium alloy for the internal structure and glass-fibre for the skin. Starting from the results obtained in a previous phase, mainly concerned with the performance augmentation, a detailed structural design is conducted. This paper describes the design of a morphing droop nose conceived to increase the performance in high-lift conditions of a twin-prop regional aircraft, while ensuring the natural flow laminarity of the wing.