Testing of a hinged wingtip device for gust loads alleviation

Recent aircraft designs have considered higher aspect ratio wings to reduce induced drag for improved fuel efficiency; however, to remain compliant with airport gate requirements, folding wing-tips have been introduced as a solution to the increased wing-span. Recent numerical studies suggest that a folding wing-tip solution may be incorporated with spring devices to provide an additional gust loads alleviation ability in flight as well. In this work, a series of low-speed steady and dynamic wind tunnel tests was conducted using a prototype of such a concept. It was found that a folding wing-tip with a non-zero relative angle of the folding hinge axis to the stream-wise direction could provide gust loads alleviation. The level of load alleviation varied with hinge spring stiffness and lifting condition, with the best performance achieving a 56% reduction in peak loading.