Folding Wingtips for Improved Roll Performance

Future aircraft designs look set to use longer wingspans to increase the aspect ratio and therefore overall aerodynamic efficiency of the airframe. Such larger wing spans also reduce roll rates and require increased control surface area to achieve the roll maneuver requirements for certification. In this work, the effect of using flared folding wingtips (FFWTs) on the roll performance of simple aircraft wings is investigated numerically and experimentally. A unique rolling rig is designed, manufactured and tested, with a series of steady roll and transient tests performed for different wing spans, with and without folding wingtips. It is shown that the use of FFWTs on aircraft wings can enable improved aerodynamic performance due to the increased span whilst also significantly reducing the aerodynamic damping due to roll, such that the roll performance of a wing incorporating FFWTs is comparable to that of one without the additional span.