Blade with curved end for a rotary airfoil of an aircraft

Blade for the rotating airfoil of an aircraft having an attachment for fixing to a hub, a current part having a leading edge and a trailing edge and whose profile has a chord of constant or evolutive length C, and a tip whose span is less than 10 percent of the total span of the blade, which extends from said current part outwardly and whose leading edge extends from the leading edge of said current part rearwardly in a sweep, said tip being in addition downwardly slanted, wherein said downward slant of said blade tip extends over the entire length of this tip and is continuous from the connection from the current blade part as far as the end edge of said tip so that said tip follows a curvature such that its extrados is convex and its intrados is concave, the downward curvature of said blade tip being at least approximately of parabolic trend, the extensionin said tip of a reference line of the current part merging with the controlled pitch variation axis of said blade, has a substantially parabolic trend, referred to a system of orthogonal axes Ox, Oy and Oz, whose origin O is situated at the connection of the reference line of said current blade part and of the reference line of said blade end, the axis Ox being aligned with the reference line of said current part and being oriented outwardly of the blade, whereas the axis Oy merges with the chord of the connection profile between said current part and said end and is oriented from the leading edge to the trailing edge and the axis Oz is oriented upwardly, namely from the intrados to the extrados of the blade, wherein said reference line of said blade tip is contained in a plane xOY passing through the axis Ox and whose plot OY in the plane yOz forms an angle .gamma. with the axis Oy and, in the plane xOY, the equation of said reference line of said blade tip is a parabolic trend function in which the coefficient of the highest degree term depends on the angle .gamma..