Abstract: A wing leading edge variable camber flap for an airplane, the flap having a pivoted bullnose and flap extension and retraction linkage mechanism for sequencing the flap into three positions of operation: a stowed position for high speed cruise operation of the airplane; a first forwardly and downwardly extended flap position whereat an aerodynamic slot is formed between the trailing edge of the flap and the relatively fixed leading edge of the wing, coupled with a steep flap angle-of-deflection of the flap relative to the wing chord plane, for low speed landing operation of the airplane; and a further forwardly extended second position whereat the trailing edge of the flap is moved to an abutment relation with the leading edge of the wing to seal off the aerodynamic slot, to form a substantially aerodynamically continuous upper surface and the flap angle-of-deflection being less than the landing position, for creating less drag during take-off operation of the airplane.

Abstract: Apparatus to compensate for airflow blockage and attendant airflow separation, loss of lift, and flap buffeting caused by the support members connecting a flap to the stationary portion of the wing is disclosed. An airflow duct, located between the lower and upper surfaces of the flap, is dimensioned and positioned such that when the flap is extended, air flowing through the airflow duct is discharged over the blocked portion of the upper flap surface. A recessed airflow channel, formed in the upper surface of the flap to direct additional airflow over the blocked region, is included for use in situations in which the flap structure precludes an airflow duct of sufficient size to fully compensate for the airflow blockage. Duct closure doors are included to seal the airflow duct inlet opening when the flaps are retracted to thereby reduce drag during operation of the aircraft in the cruise regime.