July 5, 2004 - Wing Spar Tiedown Brackets

 

The last step with the main wing spars is preparing the tiedown brackets. This took me longer than I expected. Here I am working on fashioning four rectangular spacers that go between the wing spar and the tiedown bracket. First I drilled out the hole in the spacer using the drill press and skills I developed working on the vertical stab. The key here is to drill out the hole BEFORE cutting the spacer to length. Otherwise you'd have a hard time clamping the spacer down on the drill press.

I used a hacksaw cut the spacer. I know, I'd save a lot of time if I had a bandsaw.

Here is a picture of the tiedown bracket and the wing spar. First you match drill the tiedown bracket to the wing spar, then you match drill the spacers to the tiedown brackets. I somehow managed to drill all the holes in their correct positions.
Then you have to drill holes for riveting the nutplate to the tiedown bracket. I matchdrilled the rivet holes in the tiedown bracket using the nutplate as a guide. Then I matchdrilled the rivet holes in the spacer using the tiedown bracket as the guide.
The rivets don't go through the spar. The rivet holes on the bottom of the spacers are countersunk.
Everything is drilled and deburred.
I primed the tiedown brackets and spacers with Mar-Hyde, then riveted the nutplates, tiedown brackets and spacers together. Here is the front of the right tiedown bracket and the back of the left tiedown bracket.
The tiedown bracket gets bolted to the wing spar. I still have to tap the tiedown bracket so I can screw in the tiedown rings. I ordered the rings from Van's. Only $4 each. I like the idea that they are removable. No reason to have the drag in flight.
 
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