Aileron and Flap Rigging

Time: 8 Hours

This weekends task was to finish up the fuel connection lines from the fuselage to the wing tanks and rig both the ailerons and flaps. The fuel lines consist of a connection for the vent line and a connection for the fuel feed. Since I had used flop tubes, for inverted flight, I had a little bit different fuel feed line vs the standard pick ups. The lines have to travel through the hole that was drilled in the tank attach brackets. They will also have a union in the line where the standard ones don’t. The vent lines just have to clear the brackets staying below the skin level so they will be hidden under the flashing that will get put there. I made the lines and their connections minus the end that goes on the fuel line that comes out of the fuselage. That will get cut and flared after the wings are removed to make room.  

    
   Once I had the fuel lines done I moved on to the big task of rigging the ailerons and flaps. First up is to attach the ailerons to the wings and set the neutral point. I used a digital level which has a magnet and stuck it to my control stick to get perfect neutral stick. 

 With the stick in neutral I adjusted both of the ailerons so that they were in their neutral position. This is done by aligning three tooling holes in the outboard rib and the aileron tip. When all three line up the aileron is in neutral position.  

  Once I had both ailerons on and adjusted to be in the neutral position I had to make adjustments back at the control stick to return it to the neutral position. This is done by adjusting the rod ends on the two pushrods the connect to the control stick.  Once the ailerons have been adjusted you can move on to the flaps to line them up.  Before doing this I put in the aileron judgment tool the Vans gives you to hold neutral position. This is a jig that has a hole in it for the aileron rod bolt to go through and a flat surface to sit against the wing spar. When installed the bell crank is in its neutral position but also holds the ailerons from moving.  With the jig in place I know that ailerons will not move and I can adjust the flaps to match them. The flaps need to line up with the ailerons so that as you look down the wing in neutral position the ailerons and flaps trailing edge is lined up in a perfect line. To do this with the flaps you just adjust the pushrod either up or down to get the flaps to line up with the ailerons. Before you can do this you need to enlarge the hole in which the pushrod it goes up-and-down through.  
   You need to open this whole up as when the pushrod goes up-and-down it’s geometry changes moving the pushrod forward and aft as it moves. Once you have this whole opened in the pushrod no longer hits the skin you just adjust its length to align the flaps trailing edge with the ailerons in there up position.  
 With the flaps adjusted both left and right I removed the aileron jig to check their travel in the up and down position and compare to the degrees that vans specifies.   
 All the measurements were dead on and perfect!  One thing I did find with my flaps was that I did not bend the rears are flange enough when I built the wings. This caused the wings skin to curl up just a little at the aft end of the top skin. Vans knows that this is an issue for builders and describes how to correct this with a 2 x 4 jig. I took a 2 x 4 and cut a slot in it and drilled out the center in order to bend the flange without bending the skin as I do that. 

 The idea is that the slot would allow the 2 x 4 to slide over the skin at the very tip I opened up the slot a little to slide over the rivet heads on the rear spar flange then I could use the 2 x 4 to slowly bend the flange down in turn lowering the skin. 

   This worked out well and I will do a little more tweaking on it to get it perfect. What is fun is that I can make the flaps go up and down using a 9 V battery with it’s flat motor. Kind of fun to see things working like they should!

Left Bottom Inboard Skin Done

Time: 4 Hours

I got to spend a little time in the Hangar yesterday when I got home. The task at hand was to finish up the right bottom inboard skin and flap hinge. Again I have to say that riveting these skins is a pain by yourself although I’m not sure it would be much easier with a helper. I really strain to reach the rivets at the rear spar, or top as it sits in the cradle, since the opening is so small. I was able to get all the rivets done except the 2 rows where the outboard skin overlaps the inboard since those will be the very last rivets done. I took my time and several breaks to keep my arm and back pain in check. I did have 2 small (character as my friend Glen calls them) dings, 1 from the bucking bar in the inside and 1 from the rivet gun. They are super small and the painter will have those taken care of. Good thing is that it’s in the bottom of the wing and no one would ever see them if they were bad. I then grabbed the pneumatic squeezer and hit all the inboard edge rivets along with the wing half of the flap hinge. With every rivet done that I could do now I slid the hinge pins in the flap to see how everything looked. I’m happy to say that it looks awesome!

Flaps Drilled

Time: 5 Hours

Today’s task was to get both flaps drilled to the wings. If you remember that I left the wing side of the flap hinge undrilled so that I could make any adjustments so the trailing edges of the ailerons/flaps aligned. This was the time for me to get everything aligned so I could drill the hinges. There are several areas that I had to work with. One was to keep a 1/4″ gap between the flap and aileron. Another was to keep the trailing edges of the flap and aileron straight with each other as they run from inboard to outboard. The other was to make sure I didn’t run out of edge distance on the hinge flange as I made these adjustments. I have read many builders websites where they come close to the edge distance problem. Van’s calls for a 3/16″ edge distance minimum. Edge distance is measure from the center of the rivet hole to the edge of the hole. So I drew a line on the hinge to represent my line I can’t cross for reference.

I then used my 2 spring clamps to attach the flap to the wing.

I then spent an hour fine tuning all the angles and edges until I was perfectly happy with all the alignments and drilled one hole at the outboard end and clecko’d it in place. I then rechecked all the alignments and when I was happy I drilled the inboard hole and clecko’d it as well. I rechecked all the alignments once again and when I was happy I worked my way down the line drilling a hole and cleckoing it until I had all the holes complete.

I removed the flap and the hinge and was happy to see that I was good on all my edge distances! As with all the steps on this plane the second time goes a little faster. I had lefts side done in about half the time as the right. On the right flap the inboard edge, closest to the aileron was the side that needed to be lifted or moved aft in order to get the alignment just right. To opposite was true of the left wing. I’m guessing this is normal and this is why they use this process to remove any inconsistencies in the trailing edges. This hinge is on the bottom of the wing and no one will see it so symmetry between the wings is not necessary. All in all it was a fun day in the Hangar and had a little head scratching at times.

Right Flap Done

Time: 3 Hours

I got home this afternoon from my 2 day trip and was anxious to get out into the Hangar. I repeated the entire process that I used on the left flap item for item. As with any task it always seems that the second task goes much quicker as you learn from the first one. This flap was no exception to that rule and I finished it in about half the time.

And that’s it! 2 flaps done and looking great!

Left Flap Done

Time: 8 Hours

I had beautiful weather again today so I had the Hangar door open to enjoy the day while building. The first task was to get out the tools to dimple the skins of both flap skins. I had to use the DRDT, pneumatic squeezer and my close quarters rivet puller dies to get to all the holes. I didn’t take any pictures of this as you have seen them before. Before I did any riveting I decided to work on the V block jig Van’s describes. I used the boards that I used to sandwich the ailerons. I cut two of them 14″ and left one factory end on each of them so I had a square surface. I then lined them up and screwed them together. I then used one of the exterior ribs to come up with the V angles.

A couple of minutes at the bandsaw and I had 2 identical V brackets.

I then added a couple of 2×4 legs to allow me to screw them to the workbench. I just used one of the flap top skins to determine how far apart to put the brackets.

So now was the time to start riveting. I decided that I would do an item on one flap then repeat it on the other. The first task is to rivet the single hole at the aft end of the interior ribs to the rear spar that is actually the bottom skin curled up. The interesting this is that during mock up I needed 4 shims on the left flap and when I set it up after dimpling I no longer needed them as the rib was right up against the spar! Go figure.

Next was to rivet the main spar angles to the spar making sure you leave the holes that attach to the inboard rib open for later.

I then decided to work on the piano hinge attachment point. Van’s gives you two options for the pin, leave it as one length and cut it in 2 pieces removing a couple eyelets of the hinge to access them. I chose the second as it is pretty popular and makes for easy removal of the flaps. My buddy Glen gave me a photo from his build on how he did it so I just replicated his. First up was to measure out where I wanted the ends to layout which told me which 3 eyelets to remove(2 from one side and 1 from the other). It ended up being that I wanted to leave 65 eyelets from the outboard end of the hinge, removing 66-68 eyelets. I then had the area that I would need a nutplate on the spar. I drilled matching holes on the left and right spars. I used that hole and a screw to align the nutplate to drill for the 2 rivets.

I then cut 2 eyelets to make my retaining brackets(you will get the idea at the end) and drilled them together for the screw and hit both sides with the scotch-brite wheel so the were perfectly matched.

The inboard rib gets riveted to the double plate as well as the nutplate that connects the flap control arm to the flap.

Now I had all those items done on both flaps I reassembled the flaps and set the right on the shelf and put the left in the V jig I had made.

Once you have the flap tight in the jig you can remove the spar so you have access to the inside to rivet. I got one of my bucking bars and taped it all up except on on the faces so I didn’t scratch up the inside of the skins.

I took a couple of photos to see if you can see how I used this bar. For the top to bottom skin overlap the bar just rested on the rear spar and worked like a charm.

I was able to rivet all the skin overlap holes pretty easy. For the skin to ribs I ended up using my little 3/8″ thick 1.5″x1.5″ bucking bar since it’s pretty tight in this space. It took me several hours to get all these interior rivets.

On the inboard rib there are 4 rivets at the aft end on the top and bottom that are aft if the rear spar and you have no choice but to use MK319 blind rivets here.

After you get all the interior ribs done you can slide in the spar and start riveting the spar to ribs with LP4-3 blind rivets. The lower side rivets are easy to get to but the top ones require a little manipulation of the rivet stem and the top skin. I found that my cheaper rivet puller fit pretty nice.

I then moved on to the top skin to spar holes. I tried a couple of different bucking bars with different amounts of success. I ended up using my longer 1″x1″x6″ that had an angle on one end. I also tried this one too and it worked ok as well.

Those rivets went really fast as I worked down the line. You then can work on the bottom skin to spar to hinge holes.

So that was all the rivets on that flap! It was a long day but I still wanted to finish the hinge pins so I could clean the flap and call it complete. I cut the pin in half and made several measurements and took them to the vise to make some bends. One bend to follow the spar flange and one to send it to the nutplate and retaining clip I made earlier. Once I had all the bends right where I wanted them in bent the ends just a little to keep the retaining clips from falling off when removing the pins.

I was real happy with how the pins came out. I just need to do a final trim of the other ends as I left them a little long. I then took the flap out of the jig and cleaned it all up. 1 down and 1 to go, sometime this week.