Aerofoil nose shapes delaying leading-edge separation

If an aerofoil of chord c has a parabolic nose with radius of curvature r, and is placed at angle-of-attack alpha to a stream, the laminar boundary layer on its upper surface remains unseparated for alpha < 0.818<root>(r/c). In the present paper we consider some smooth local modifications to the leading edge. Symmetric modifications of the nature of local sharpening of the nose can improve this result to at least alpha < 0.897<root>(r/c). Further improvements are possible for unsymmetrical (e.g. drooped) noses, and an example of a 'drooped' nose with alpha < 0.912<root>(r/c) is shown.