Wind-tunnel tests on the NPL 434 nose-slot suction aerofoil

Abstract

Stalling tests were made on the 8 per cent thick section NPL 434, which has been specially designed for nose-slot suction. At the higher suction quantities, the maximum lift of the aerofoil was considerably greater than for the Lighthill and Glauert sections previously tested when due allowance was made for the difference in camber. At low suction quantities, there was no improvement. Tests with various slot widths showed that the velocity into the slot as well as the suction quantity was important in relation to high maximum lift, and that the values of CLMAX achieved with suction were determined more nearly uniquely by the momentmn coefficient rather than by the quantity coefficient. Static pressure measurements made in the slot and ducting indicated that the suction head required at the stall was high, being at least equal to the dynamic head in the slot throat, but that some reduction could be expected from improvements in the slot entry shape.