 Battens and Leading Edge Stiffener   Sail Material and Panels   Pockets and Hardware   Cables and Hardware   Sail Attachment to Wing Frame  As discussed in the aerodynamics section, stiff preformed  battens are the airfoil ribs that maintain the airfoil shape from  the root to the tips. Additionally, a foam or mylar stiffener is  inserted in a pocket at the leading edge to keep a rigid airfoil  shape between the battens from the leading edge up to the  airfoil high point. Double surface wings have additional ribs  on the bottom surface that are straight or formed to maintain  the bottom surface camber.  Sail material is a combination of polyester materials designed  with different weaves, thickness, and orientation to fi t the  design mission of the wing. Panels are cut to different shapes  and laid down at different angles to provide the stiffness  and flexibility where needed for the specifi c wing design.  Automated machines typically cut the fabric to precision  tolerances and the panels are sewn together with high strength  thread.  Pockets are added for battens and hardware is installed for  the wing frame and wire attachments. Trailing edge line or  wires are sometimes added for reinforcement and can be used  for tuning. Battens are held in with a variety of batten ties or  other methods unique to the manufacturer.  [Figure 3-12] Cables are used throughout the wing frame and sail to hold  components in place and act as structure to carry loads. Flight  and ground cables are stainless steel and attach to components  with tangs or other hardware depending on the application.  Cables are secured at each end with thimbles and swaged  fi ttings.  Figure 3-5  shows detail of typical swaged fi ttings.  A variety of hardware is used for attaching these swaged  cable fittings to the airframe. Each manufacturer has different  hardware for wing components.  [Figures 3-14  and  3-15] The sail is attached to the wing frame at the nose and the  tips. A keel pocket towards the back of the sail secures the  sail to the wing keel.  [Figure 3-13] Figure 3-12. Trailing edge of the sail showing reinforcement panels,  trailing edge line, and batten ties with attachment hardware.  Figure 3-14.  Crossbar tensioning junction attachment example. Figure 3-13.  Keel pocket. 3-7