Rear Wing Rib Blanks

Work and and social obligations (read as: "hangovers") kept me from building this weekend. An interview with Charlie Becker (EAA) reminded me that even 10-15 minutes here and there helps to see the project through. I did about 30 minutes today drilling and cutting my rear rib blanks. Its good to be another couple steps closer with 4 rib blanks.  If I do that everyday, I think it will make a big difference on the project.

Below I drilled the inside corners so there are not any sharp corners when I make the cuts.



Then I used the Andy Shears to cut all four blanks by hand.  It's pretty quick.  Also, the rib blanks do not have to be exactly the same (that should be the goal, of course).  It is the form block that ultimately makes the shape the same for each rib.  If you're flanges are half a millimeter different because of your cuts, that really won't be an issue.  So don't feel pressured to use the router setup if you want to save a little money.  For me, I just like to be able to hear the radio instead of a router.

Making Ribs

I mounted the aluminum angle brackets on the right wing and started making the ribs this weekend.  I decided to primer the brackets like I did for the other spar pieces.  I am not going to primer the ribs.

For making the ribs, I followed the 6 part video series on the EAA website for making aluminum ribs.  

Here is a shot down the right spar with the half inch holes now drilled too.  

Here is a closeup of a leading edge rib bracket made from 3/4" .062 aluminum with AN3-6A bolts (The bolt size varies depending on the location along the spar) holding it in place.  I had to do some digging, but was able to find that the AN4 bolts should be torqued to 50-70 inch lbs of force (notice that is inch lbs and not foot lbs.  Big difference!).  There is a really great write up here that I printed for future reference in the shop.

I didn't take a lot of pictures of the rib forming process since I'm basically following the EAA video.  In the far background you can see my rib forming blocks.  One thing to keep in mind is to mark the fluting positions on your ribs.  You need to do that so your rivets fall in between them when you attach the skins.  

I'm fluting my ribs with this tool. It works fine.  I kind of wish it made smaller flutes though.

To flange the lightening holes, I'm using the process described by Dave Thatcher in the build manual.  It doesn't require an expensive die and is easily duplicated if needed.  You just use the fly cutter that cuts the lightening holes in aluminum.  You cut halfway from one side of the block, then flip it over and cut halfway from the other side.  You end up with a die like the one below that you place into the forming block to force the flange.  I've been using a hammer, but I might try the arbor press I used for riveting next. 

Main Spar Complete!

Today I attached the left wing to the center spar.  Finally done with the spar and can start to attach rib brackets.

Right Dihedral Set

I built up the courage to set the dihedral today in the right wing.  I measured about 150 times first!  Right now the wing bolt holes are just 1/4", but I'll drill those out when I get my 1/2" bolts.

I was happy with this process that I picked up from Brandon Bergdorf's blog.

The aluminum angle I had wasn't long enough, so I had to use three pieces clamped together.  If the pieces sat inside the other two to make it clamp to.  Worked out well.  You can stretch a piece of string along the aluminum to make sure it is straight too.

Clamped a rule in here to hold everything in place.  I also used a little hot glue to temporarily keep the blocks and aluminum from moving.  Worked well.

Here I am checking that I got it right.  It's 7" on the nose!

Boss lady says its time to clean up for company.  Hope to do the left wing in the morning before the July 4th festivities kick off. 

Completed All Spar Rivets and Planned Dihedral

I spent 5 hours today riveting the left wing and playing around with setting the dihedral.  I'm now done with all of the riveting on the spars.  I chickened out on drilling the holes to actually set the dihedral and decided to look online.  I like Brandon Bergdorf's method of using aluminum angle as a guide.  I think I'll try that in the morning instead of building an elaborate jig.