Gust Load Alleviation via Active Folding Wingtip Concept: Experimental Approach

This paper presents an experimental investigation into gust load alleviation using an actively controlled folding wingtip concept. The system employs a proportional–integral–derivative controller driven by real-time feedback from the wing root bending moment (WRBM) to dynamically adjust the wingtip deflection during gust encounters. Experiments were conducted in a closed-circuit wind tunnel under both [Formula: see text] and harmonic gust excitations, covering a range of gust frequencies and angles of attack. Time-domain measurements of WRBM and wingtip angle were used to evaluate performance based on two metrics: i) peak load reduction relative to a fixed-tip baseline and ii) cycle work, quantifying control effort and hysteresis. The active folding wingtip achieved consistent load mitigation across the test envelope, with maximum reductions of approximately 44% in positive peaks and 31% in negative peaks near the first bending resonance. A clear correlation was observed between enhanced load relief and increased actuation work, providing guidance for gain scheduling and actuator sizing. Overall, the results demonstrate the effectiveness of feedback-controlled folding wingtips as a practical, broadband approach for gust load alleviation in high-aspect-ratio wings.