Testing of wing-tip spring device for gust loads alleviation

Recent aircraft designs have begun considering higher aspect ratio wings in order to reduce induced drag for improved fuel efficiency. In order to meet airport gate requirements, folding wing-tips have been introduced as a solution to the increased wing-span. Recent numerical studies have suggested such a folding wing-tip solution may be incorporated with spring devices in order to provide an additional gust loads alleviation ability in flight. A series of low-speed wind tunnel tests was conducted using a prototype of such a concept and found that a folding wing-tip with a non-zero relative angle of the folding hinge axis to the stream-wise direction can provide gust loads alleviation. It was also concluded that the weight of the wing-tip may have a strong influence on the hinge stiffness necessary for best performance. The findings from these tests agree with previous simulations in a qualitative manner.