Leading Edge Tube Leading Edge Tube Nose Plates Keel Crossbar Upper Cables—Ground Wires King Post Downtubes Control Bar Control Frame Crossbar Lower Cables—Flying Wires Crossbar Tensioning Cables Crossbar Tensioning  Cables Attachment Figure 3-2.  Wing frame components. Figure 3-3.  Leading edge assembly. Wing Tip Outboard Inboard Crossbar attaches here Nose plate attaches here Internal Sleeve External Sleeve Outboard leading edge release for short pack  Keel  The wing keel is like that of a boat keel, the center of the  wing, fore and aft. It attaches to the leading edges at the nose  plate and performs a number of important functions. It is the  structure where the carriage attaches to the wing, and it is the  wing structure that connects the center section of the sail at  the “keel pocket” (discussed later in this chapter in the sail  section). The control frame and king post (if so equipped) also  attaches to the keel. It also provides structure for the upper  and lower wires (if so equipped) and a reference or anchor  for the crossbar which needs some movement in relation to  the keel for roll control.  The keel is rigid and is not designed to fl ex nor is it highly  stressed like the leading edges except where the under  carriage attaches to the wing. Sleeving is normally added to  strengthen this middle area as well at the nose attachment  and rear cable attachments.  3-3