Effect of Aspect Ratio on Gurney-Flap Performance

Abstract

A low-speed wind-tunnel investigation has been undertaken to establish the effect of wing aspect ratio on Gurney-flap performance. Characterization is accomplished using a force balance and flow visualization. The Gurney-flap lift increment due to a shift in the zero-lift angle of attack was observed to scale with that of the lift-curve slope for different aspect ratios. As the aspect ratio reduced, a Gurney flap of greater height was required to maximize aerodynamic efficiency. The dependence of aerodynamic parameters (zero-lift angle of attack, minimum drag coefficient, and lift-curve slope) on the Gurney flap’s height-to-chord ratio was also examined.