Abstract: The invention provides a rotary aircraft airfoil comprising 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, and a tip which extends said current part outwardly and whose leading edge extends the leading edge of said current part rearwardly in a sweep, said tip being in addition downwardly slanted. This blade is remarkable in that the downward slant of said blade tip extends over the whole of the span of this tip and is continuous from the connection with 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.