Titanium!

One of my goals with this plane is to make it extremely lightweight.  I don't have a firm weight target yet, but definitely sub 1600lb.  As I go though all of the parts I can't help but think, I could make this lighter if I... make it out of carbon fiber, drill holes in it, fabricate it out of titanium, get rid of it, etc.  Three of those items are the steel wing tie downs.  I had some scrap titanium lying around and by re-making these piece I achieved a 40% weight savings!  or 4oz depending on how you look at it.  While 4oz doesn't seem like much, it adds up after you do it over and over.  

When welding titanium, every part of the joint must be shielded with argon.  I made this tent to cover the back side of the welded and tape it on with aluminum foil tape.  

Here's the bung, welded in place.  Very slight oxidation (straw colored) is acceptable in the weld, anything more (brown, blues, purple) is cause for rejection.  

The back side came out great! No contamination.  

Here are the finished pieces.  The steel ones are on top.  I could probably save a little more weight on the Ti ones by rounding the corners!