Influence of the aspect ratio on the aerodynamics of the delta wing at high angle of attack

The influence of aspect ratio on the contribution of the leading-edge vortices to the loading of the delta wing has been studied experimentally. The study is based on surface pressure measurements of four wings having aspect ratios of 1.07-2.80 (55 ⁤ 75 deg sweep angles). Results show that the suction induced by the leading-edge vortices increases with incidence as long as they are not affected by vortex breakdown. In higher-aspect-ratio wings, when vortex breakdown is present on the wing, the vortex-induced suction continues to increase with incidence at a decreasing rate until the breakdown has reached the apex region. In lower-aspect-ratio wings, however, the vortex-induced suction decreases with incidence as the breakdown crosses the trailing edge. The magnitude of the slope of this decrease is smaller in lower-aspect-ratio wings. This may indicate that lower-aspect-ratio delta wings are preferable for future aircraft designed for poststall flight.