Abstract: A releasable fastening device for securing workpieces together in a firm and intimate relationship is disclosed. The fastening device is sometimes referred to as a "blind fastener". The fastener comprises a bolt member including a head located on one end of the bolt and extending outwardly therefrom to support an upper workpiece and a shank with an annular recess, the shank being insertable within said through axially aligned apertures located in the workpieces. An expandable device, preferably in the form of a stiff spring is inserted and is confined within the annular recess. When the spring is in its expanded position, it extends beyond the shank along a bottom surface of a lower workpiece thereby along with the head on the bolt member holding the workpieces together in a mating relationship.

Abstract: An airfoil with an adjustable aerodynamic shape for lowering the landing speed of high performance aircraft. A thin secondary skin is applied to the top primary skin of the aircraft's wing surface. Pressurized fluid is introduced to the cavity formed between the primary skin and the secondary skin to cause a rounding of the upper surface of the airfoil in conjunction with lowering of leading and trailing edge flaps. A plurality of contour members of predetermined lengths and at spaced locations connect the secondary skin and upper surface of the primary skin so as to define the particular contour desired. The leading edge of the secondary skin is hinged to the forward spar of the airfoil. One or more actuators acting through a linkage apply tension to the trailing edge of the secondary skin and draw it down into contiguous relationship with the primary skin of the wing surface for high speed operation.