Trailing edge flaps having spanwise aerodynamic slot opening and closing

Abstract

An aircraft wing for use in a STOL aircraft incorporating upper surface blowing engines employs trailing edge flaps, including a main flap segment and an aft flap segment. The flaps are mounted on and externally hinged below the wing for movement between a retracted position and a plurality of extended positions. The main flap segment is hinged to its support for pivotal movement about a spanwise axis. The main flap segment is in a first position when retracted and normally remains in that position as the flaps are extended. When the flaps are extended and the main flap segment is in the first position, the upper airfoil surfaces of main flap segment and the aft flap segment form a smooth, continuous upper surface that extends downwardly and rearwardly from the upper airfoil surface of the wing. When the flaps are extended, the main flap segment can be pivoted about the spanwise axis to a second position to form spanwise slots between the forward portion of the main segment and the aft portion of the wing and between the aft portion of the main segment and the forward portion of the aft segment. In the first position, wherein the smooth, continuous, downwardly and rearwardly extending upper airfoil surface is formed, the trailing edge flap system can be employed with an upper surface blowing engine to take advantage of the Coanda effect to turn the exhaust stream issuing rearwardly and chordwise across the wing to turn the exhaust stream downwardly and rearwardly, thereby creating an upwardly directed, engine-generated lift component to augment the aerodynamic lift generated by the wing and flap structure. In the second position, the spanwise slots function to enhance the aerodynamic lift generated by the wing/flap combination as it moves through the air by allowing ambient air to flow through the slots.