U.S. Patent Specifications

In an aerofoil construction that includes a main aerofoil portion and a semi‐floating droopable section flexibly suspended at its upper inner surface by an integral flexible portion thereof from the adjacent surface of the main aerofoil portion; means for positively and pivotally supporting said section for down‐wardly rcflexing same, comprising: a support attached at one end to, and projecting longitudinally from, the main aerofoil portion; a link disposed between the unattached end of the support and the upper inner surface of said section and pivotally connected at its ends to the support and to said section; and an actuating member for reflcxing said section pivotally attached to the lower adjacent surface of said section, the aforesaid pivot points together defining a triangular truss‐like structure having rigid sides disposed under the flexible portion of said aerofoil construction, said sides being pivotally adjustable by the actuating member into positions defining a scries of triangles taking all the stresses in all positions of said flexible portion except those due to flexure of the latter and to aerodynamic forces.