Lift and drag measurements were made to determine the effects of vertical flaps when positioned along a ray on the upper surface of a sharp-edged, flat, 60° delta wing. Six flap heights were tested at each of four semi-span positions.
Results showed that all configurations gave improved lift-drag ratios. The maximum improvement was 33% using a flap of height 6·1% of the local semi-span placed at the 84% semi-span station. The flaps did not affect the lift but reduced the drag by generating a thrust force on the vertical flap surfaces.
Flaps at the 84% position were modified to investigate the possibility of obtaining further increases in lift-drag ratio. In practice these modifications, inward inclination of the flaps, and fairing the inboard side of the vertical flaps, slightly reduced the flap effectiveness and were hot pursued further. Part chord flaps were also tried and showed that the reduction in benefit was roughly proportional to the length of flap removed.