Aeroelasticity study of high span ratio wing with flare folding wingtip

Abstract

Flare folding wing-tips rely on the adaptive deformation of the structure to reduce the flight load, which can effectively simplify the control system, and has more advantages in cost and weight. To study the effect of the elastic folding wingtip as a passive load alleviation device, the flexible hinges were used to connect the folding wingtip to the wing, and the Doublet Lattice panel method was used to calculate the aerodynamic loads. Static and dynamic load response and flutter analysis were performed on the folding wingtip configurations with different structural parameters, and the effects of the hinge orientation, stiffness, wingtip weight and wingtip center of gravity position on the load response and flutter behavior were investigated. The results show that the flare folding wingtip can significantly reduce the static and sudden wind loads of the wing with suitable parameters. In the static aeroelastic trim analysis, the folding wingtip can increase the span length by 25% with almost no increase in the wing root bending moment and reduce the trim angle of attack by 0.14°. In the gust response analysis, the maximum wing root bending moment can be reduced by nearly 50% comparing with the fixed wing tip, which is only 17% higher than the baseline model without the wing tip. However, the flutter velocity is reduced, and further optimization is needed to improve the flutter characteristics.

Keywords

• flight loads
• gust response
• folding wing tips
• gust load alleviation
• flutter