Experiments on a 60-degree delta wing with rounded leading-edge vortex flaps

Low-speed wind-tunnel measurements were done on a 1.15-m span 60-deg delta wing with rounded leading-edge vortex flaps. The purpose of the measurement s is to assess the benefits of the rounded leading-edge vortex flaps in reg ard to improving the lift/drag ratio of delta wings. Force and surface pres sure measurements were made at a Reynolds number based on a centerline chor d of 2 x 10(6). The increase in the radius of the rounded leading edge redu ces the drag significantly both with and without Rap deflection except in t he minimum drag region. Deflecting the rounded leading-edge vortex flap imp roves the lift/drag ratio at relatively higher lift coefficients, when comp ared with the sharp-edged vortex flap, The largest improvement in the lift/ drag ratio as compared with the sharp-edged delta wing with vortex flaps is more than 25% in the lift coefficient range between about 0.6 and 0.8 for the rounded-edge delta wing with flaps that were deflected 30 deg downward.