Abstract: A wing for a wind rotor of a windmill has a main part and a turnable part that serves as an aerodynamic brake. The main part of the wing has an outer end spaced radially inward from the wing tip and a notched partial-chord edge portion extending radially inward from the outer end for part of its length. The turnable part includes a first section and a second section. The first section is a full-chord outer tip portion of the wing that extends radially outward from the outer end of the main part of the wing. The second section is a partial-chord portion that extends radially inward from the first section in the notched region of the main part of the wing. Hinges located at the outer end and at the radially inner extent of the notched edge portion of the main part connect the second section of the turnable part to the main part for turning about a pivot line between a stowed position and a deployed position.