Deformable Morphing Leading Edge of an Actively Blown High Lift System

Abstract

A smoothly varying extreme-displacement morphing droop-nose as a novel high-lift device has the potential to improve aircraft flying efficiency, reduce emitted noise, and reduce take-off and landing runway lengths. Regional aircraft featuring such a novel high-lift system could be operated from more distributed airports, reducing congestion at major hub airports whilst facilitating the growth of air transportation. These advantages are aligned with the Vision Flightpath 2050 of ACARE. This new device is being investigated by the multidisciplinary Collaborative Research Center 880 (Sonderforschungsbereich 880) in Braunschweig, Germany. This work outlines the structural design and demonstrator testing of the extremely deformable droop-nose device. The droop-nose can be categorised into three components: First, the skin, second the internal support structure and third the actuation system. A design chain has been established based on optimization tools such that the device can move to a prescribed target shape whilst resisting external loads. A new hybrid skin concept featuring HexPly®913 glass-fibre composite in combination with EPDM rubber has been established and allows very large deformations resulting in morphing-strains in the order of up to 1.5%. Multiple skin sections are defined which enable a smooth gradation from thick to thin skin segments. Afterwards, the skin is optimized in terms of thickness-distribution (physically realized through dropping-off plies along the perimeter of the droop nose) and the position of stringers. For initial designs, the skin has been supported by a conventional kinematic substructure. A prototype has been built based on a 2D section of the leading edge and strain gauge and optical shape measurements have been performed as an initial assessment of the device. The investigation of compliant mechanisms to transfer actuation force and displacement onto the skin in a more integrated manner is also being investigated. The 2D design is also being extended into 3D design, and the effects of wing bending due to aerodynamic loads as well as landing impact are under investigation. Considerations of anti/de-icing are also being made.