Lift enhancement using a close-coupled oscillating canard.

Abstract

A wind-tunnel study to investigate the effects of dynamic stall of a closecoupled canard on the canard/wing vortex interaction for increased lift enhancement was conducted. Two angles of attack of the model were studied: one at the first stall condition of the wing and one in the post-stall regime where a strong leading-edge vortex was formed. Baseline force and moment parameters were measured at mean canard deflections based on those determined to be optimum for the static case, as were mean values ± 3 degrees about the optimum. The amplitude of oscillation considered was ± 5 degrees about each mean; reduced frequencies tested were from 0.046 to 0.232. For most cases, lift was enhanced beyond the static-canard case at mean deflections equal to those at or greater than the static optimum value. The effective lift was decreased for mean deflections less than those previously determined to be optimum. Lift enhancements were generally 2 to 6 percent higher than the values determined with the static canard. The increased lift was generally independent of reduced frequency and peaked between k values of 0.1 to 0.2.