Retractable Wing Tiedowns

Funny how we can get hung up and consumed by the little things.  These self-retracting tiedowns are such simple little things but have required a substantial amount of thought and work to make them work.  They are simple as can be but it took a great deal of time and effort to get them that way.  The concept was to creat tiedowns that were robust, lightweight, maintenance free and didn't require a lot of machining.  I think they came out pretty well on almost all points.

I didn't take any photos of the wind tiedowns other that those shown below.  This photo shows the tiedown for the tail but the construction of all the tiedowns was basically the same.  They are all self-retracting by use of a counter weight and do not require any springs or maintenance.
The tiedown was mounted to the main spar with a metal plate on the back side of the spar.  This photo shows the mounting and the grounding strap from the fuel cap attached before wing closeout.  The ground strap is part of a common ground that will run from all metal connections on the wing to the firewall common ground.
Once the wing was close out, I filled the opening around the tiedown and left only about 1/8 inch opening around the tiedown.  The close position is flush with the wind surface.
The open position is shown here.  It is self retracting without the use of a spring which should make it maintenance free.