The effect of folding wingtips on the flight dynamics of an aircraft with elastic wing

In recent years, the development of lighter and more efficient transport aircraft has led to an increased focus on gust load alleviation. A recent strategy is based on the use of folding wingtip devices that increase the aspect ratio and therefore improves the aircraft performance. Moreover, numerical studies have suggested such a folding wingtip solution may incorporate spring devices in order to provide additional gust load alleviation ability in flight. It has been shown that wingtip mass, stiffness connection and hinge orientation are key parameters to avoid flutter and achieve load alleviation during gusts. In this paper, after defining a simplified aeroelastic model representative of an symmetric aircraft, considers the case of adding movable wingtips. The effects of hinge position, orientation and spring stiffness will be considered in order to evaluate the potential of this technique for gust load alleviation. Moreover, is studied the longitudinal flight dynamics of a rigid aircraft with elastic wing and folding wingtips.