Three-position variable camber Krueger leading edge flap

A variable camber flap assembly having a linkage mechanism arranged and actuated in a chordwise plane for extending a flap to first and second forward operative positions from a stowed position within an undersurface of an airfoil, said flap assembly comprising:

• a flexible flap panel having leading and trailing edges;
• a bullnose member having a trailing edge which is mounted to said leading edge of said flap panel for chordwise rotation, said edges of said bullnose member and said flap panel being mounted together along a hinge joint which extends generally perpendicular to said chordwise plane so that a substantially continuous aerodynamic surface is formed by said member and said panel;
• a flap chord beam having a first end pivotally mounted to said bullnose member and a second end mounted to a trailing edge portion of said flap panel;
• a drive arm pivotally mounted to fixed structure of said airfoil for rotation in a chordwise plane, said drive arm having first and second angularly spaced apart pivot connections;
• a first linkage subassembly operatively interconnecting said first pivot connection on said control arm with said flap panel, said first linkage subassembly comprising:
• means for extending said flap panel in a downward and forward direction from said stowed position to said first and second operative positions;
• and
• means for rotating said bullnose member outwardly about said first end of said chord beam as said flap panel extends from said stowed position to said first operative position, so that said trailing edge of said bullnose member and said leading edge of said flap panel which is mounted thereto at said hinge joint are pivoted toward said trailing edge of said panel, so as to foreshorten the distance between said edges of said flap so that said flexible flap panel curves outwardly to increase the camber of said flap;
• and
• a second linkage subassembly operatively interconnecting said second pivot connection on said control arm with said flap panel, said second linkage subassembly comprising:
• means cooperative with said first linkage subassembly for positioning said trailing edge portion of said flap panel relative to a middle portion of said flap panel so that said flap panel is positioned in a first predetermined angular orientation in said first operative position, and in a second predetermined angular orientation in said second operative position;
• and
• means for positioning said trailing edge portion of said flap panel in a first predetermined location relative to a leading edge of said airfoil in said first operative position so as to form an aerodynamic slot therewith, and for retracting said trailing edge portion of said flap panel rearwardly to a second predetermined location relative to said leading edge of said airfoil in said second operative position so as to form an aerodynamic seal therewith.