Cropped Wing Research Articles

Ground effect on a cropped slender reverse delta wing with anhedral and Gurney flaplike side-edge strips

The ground effect on the aerodynamic coefficients of a cropped slender reverse delta wing equipped with anhedral and Gurney flaplike side-edge strips was investigated experimentally at Re = 3.82 × 105. In a free stream, the 30% cropping was found to cause a minor reduction in lift CL and drag CD coefficients but a promoted stall compared to the noncropped wing. The anhedral caused further CL decrease and CD increase. Meanwhile, the application of side-edge strips produced a significantly increased CL and CD with a minor change to the CL/ CD ratio as compared to the baseline wing. In ground effect, the cropped wing was, however, found to generate more lift compared to the noncropped wing as the ground was approached. The joint anhedral and SES produced a great increment in both CL and CD but a virtually unchanged CL/ CD ratio compared to their outside ground effect counterparts. The larger the side-edge strips’ height the larger the increase in CL. In short, the cropping led to a weight reduction while the addition of anhedral and SES produced a large lift augmentation of the Lippisch-type wing-in-ground effect craft.

Recent Studies of Subsonic Vortex Lift Including Parameters Affecting Stable Leading-Edge Vortex Flow

Various subsonic configurations that develop vortex lift are examined herein. Comparisons are made with data and the combination of direct and indirect edge forces through use of the suction analogy. For most configurations, the use of the indirect or augmented vortex lift leads to improved agreement with data. The studies conducted showed that it is possible for the leading-edge vortex to exhibit sudden enlarging on a cropped wing and for the wing longitudinal aerodynamic characteristics not to show the effect. It was further found that the distributions of leading-edge suction correlate well with the maintenance of vortex-flow aerodynamic characteristics. Lastly, an approximate method is presented for relating the initial value of circulation and axial velocity of the leading-edge shed vortex to the wing geometry.