In some embodiments, an airfoil comprises a proximal end; a distal end opposite said proximal end; a distal portion extending adjacent said distal end; an edge extending between said proximal end and said distal end; and a surface extending between said proximal end and said distal end, said edge and said surface defining a sweep and a cahedral through said distal portion, wherein the distal portion extends over an acoustically active portion of the airfoil.