Non-linear Dynamics of the Flared Folding Wingtip Concept

Abstract

High-aspect-ratio wings offer a direct method to improved aerodynamic efficiency through reduced induced drag, but their increased span also increases structural loads, aeroelastic sensitivity and creates airport-gate compatibility
challenges. The Flared Folding Wingtip (FFWT) concept addresses these competing requirements by combining an outboard folding panel with a flared hinge axis. When released during a gust encounter, the folding motion can reduce the local wingtip angle of attack and unload the outboard wing, thereby reducing the Wing-Root Bending Moment (WRBM). Previous numerical and experimental studies have demonstrated the potential of the concept, but also show that its performance depends strongly on hinge dynamics, release timing and post-gust oscillatory behaviour. This paper presents the development and application of a non-linear, time-domain aeroelastic framework for analysing FFWT release dynamics. The framework couples a Simscape Multibody representation of a flexible main wing and rigid folding tip to an aerodynamic solver based on an Unsteady Vortex Lattice Method (UVLM). The model is used to assess prescribed release strategies as well as based on hinge moment, under discrete vertical gust excitation. The results show that the FFWT response is governed primarily by release phase: early release reduces the critical WRBM peak, whereas release at the locked peak-load instant consistently increases the critical WRBM response. A subsequent hinge-parameter study shows that low hinge stiffness improves load alleviation but increases demands on the hinge angle, while damping mainly affects post-gust dynamic quality. For the simulated configuration, the best compromise is obtained with a low-to-moderate post-release stiffness, sufficient damping, and a low hinge-moment threshold, retaining most of the peak-load reduction of the most compliant setting while substantially reducing hinge-angle demand.