Rudder 7-11-2 to 7-12-5

Only two steps left to complete the rudder, form the leading edges and attach the counterbalance weight. Getting close now!

To begin with, I formed a bend on the leading edge of the right skin, and therefore decided to have right skin as the overlapping skin. I used the Cleaveland edge forming tool to do this, and it was easier to do this on the right skin, especially at the top section due to the direction of pulling the tool.

After researching VAF forums and other builder logs, and reading Van's section 5 over again on the best techniques for rolling leading edges, I felt comfortable enough to begin. I had purchased a 1.25" 3ft long wooden dowel to use for the initial bend, along with Gorilla brand duct tape.

Starting at the top leading edge section, I cut a piece of duct tape the length of the section and taped about 1/2" width onto the skin. I then placed the dowel over the tape and skin, and made sure that the dowel was parallel to the rudder spar. 

I had read on Van's forums that the skin should be rolled parallel to the spar rather than parallel to the edge of the skin. The reason for this is that the skin tapers along its length, and by rolling parallel to the spar, the bend forms in a way that allows the skins to come together more evenly.

Starting the initial roll on the top section was easy as it is very short. I bent each skin to about 45 degrees, then removed the dowel and duct tape to continue forming the bend by hand. I gradually continued the bend on each side, a little at a time, while regularly looking down the spar to ensure the skins were coming together evenly. I had to carefully flip the rudder over several times as I worked on each side. Once the skins were overlapping and the holes looked lined up, I clecoed them together and then proceeded to roll the next section.

I followed the same process rolling the middle section. The only difficulty was forming the initial bend with the dowel as there is more skin to roll. I used the vise grips for leverage and pushed down hard on the dowel to ensure the skin didn't lift from the table as it was rolled. Once the skins were again at a 45 degree angle I removed the dowel and tape and continued the roll by hand. The middle section took longer to finish rolling, but I took my time, and took care to massage any waviness out of the skins as I formed different parts. Once the skins were overlapping and clecoed together, I didn't see any pillowing between the clecoes, so I was extremely happy with that. 

At this point, I decided to call it a night and continue the remaining section the next day. Fingers do take a bit of a beating as the skins come together, as you need to keep moving the skin being rolled to the inside once they get close and start to overlap.

Getting there... bending complete on 2 of 3 leading edge sections

I finished rolling the leading edge by getting the third and final section rolled. This section had more taper than the other two, but I was able to get the skins pretty close although I wasn't able to roll them together quite as much as the other two sections, but good enough to cleco together with not a lot of spring-back.

All 3 leading edge sections rolled and clecoed

Looks good from the inside...

Next steps to finish the leading edge involved upsizing the holes to #30. For this I used a #31 drill bit and then finished the holes with a #30 reamer. I noticed some pillowing after I had drilled the holes, but it turned out to be caused by aluminum chips that had become trapped between the skins during drilling.

After removing all clecos and deburring the holes, the pillowing disappeared. I then proceeded to blind rivet the skins together using the pneumatic rivet puller. This was fairly straightforward although I had to ensure that the rivet puller was held firmly and squarely against the skins as I squeezed the trigger.

...and from the outside

After setting all the rivets, although there was no visible pillowing on the outside of the skins, I did notice some pillowing inside along the middle of the bottom rolled section. The skins must have pulled apart slightly as I was pulling the rivets, but I am not sure why, and whether this is an issue. In any case, that pillowing is not visible from the outside.

Rudder leading edge done

With the leading edge formed, all that is left is to install the counterbalance weight and fold the skin over it. I began by clecoing the skins to the ribs through the holes that were not riveted yet, centering the counterweight in place, clamping it down and match drilling a #19 hole in the top rib. 

I then started the bend of the skins around the counterweight. This was done by hand, just enough to form a crease in the skins. I then prepared a couple of wooden blocks (with a rounded edge and holes to accommodate the skin dimples) that would be used to form the rest of the bend.

Forming the skin bend around the rudder counterbalance weight

Wooden blocks - one with 1/8" rounder edge and holes drilled to clear the skin dimples

With the wooden blocks clamped in place, I found it much easier to do the initial bend by hand. This got me to around 70-75 degrees. Then tapping with a soft head hammer along the bend got it to the required 85 degrees.

With the bends complete, I taped the skins tight using duct tap and masking tape and marked the holes in the skins to accept the screws. I found it easier to use a center punch to form the dimple mark rather than tapping a #19 drill bit with a hammer as described in the plans.

I then drilled #40 through the dimples and upsized and match-drilled to #30. I finally had to upsize the holes to #19, and here I ran into an issue with one of the holes, because the drill bit caught on one edge of a hole and created a bigger burr. I removed the burr, and deburred all other holes, however, when I went to dimple the holes for a #8 screw, I noticed a small crack at the edge of the dimple in the hole that previously had the large burr. The crack must have been left over from the burr and gotten longer as the dimple was formed. 

After researching online for possible remedies, I decided the best thing to do would be to file away the crack. Luckily the crack only extended part way up the dimple so it was easy to file away that small part. I made sure the crack was completely removed, and there were no sharp corners left from filing. I'm not worried about the strength of the dimple because it will be sandwiched between the lead weight countersink and the other skin dimple.

#19 holes drilled and dimpled

Next I had to countersink the holes in the lead weight to accept the dimples. This was done on the drill press.

Rudder counterweight drilled and countersunk

Finally, I attached both nutplates to the ribs, and screwed the counterweight in place. I did notice some pillowing between the skins, so I also went ahead and installed a CS4-4 rivet as suggested in the plans.

Rudder counterweight attached in place with screws and an extra blind rivet holding the skins

All that remained now was to finish riveting the skins to the ribs in the 12 holes that were left open. One thing I noticed after doing this is that there was a slight deformation in top right skin near the bend. I think this was caused by focusing too much on having the skin edges line up parallel as I was marking the holes for the screws. I should have just held the skins as tight as possible and not worried about the edges lining up exactly. Any misalignment of the skins could easily then be filed away if needed. The deformation is minor so I am not worried about it, but I'll keep this in mind next time I am required to bend skins.

Final rivets set in the rudder...

... and the rudder is COMPLETE!

With that, the rudder is complete (at least section 7 of the plans is). I had to pull out the vertical stabilizer so that I could see the parts together. So far, I'm very happy with how everything looks, even with the minor imperfections.

Vertical stabilizer and rudder fit together nicely!

Build Hints

• Roll leading edges parallel to the spar rather than the skin edge. This will result in a better fit
• Do the initial skin roll with dowel/rod and tape to no more than 45 degrees. Finish the roll by hand.
• Try to remove any skin waviness as the hand rolling progresses. Keep checking to make sure the skins are coming together evenly.
• When hand rolling, pull the skin in with your fingers, while pulling up on the edge to keep the skin from creasing near the spar. When the roll is complete, the skin edges should be parallel with the holes overlapping (or close to it).
• Be sure to debur after upsizing and match drilling holes in rolled leading edges. I thought I could get away with just using a drill and reamer, but due to the number of metal chips created from drilling, a lot get caught between the skins and need to be cleared away.
• While pulling rivets along rolled edges, make sure to hold the rivet puller firmly against the skin to keep the rivet head on the skin while pulling.
• When starting the skin bend around the counterbalance weight, take care not to crease the unsupported skin near the very top. This is because the counterbalance weight does not extend to the very top of the skin.
• Be very careful drilling holes in thin skins with larger bits (#19 or bigger). Have some wood supporting the skins from behind, and make sure to drill perpendicular to the skin at all times.
• When forming skin bends, keep the skins tight and don't worry if the skins don't line up exactly. Trying to force the skins to align after bending causes other issues such as skin deformations when the skins are riveted.
• Guidance from Van's on fixing dimples with cracks: In instances where cracks have occurred on this part and the crack is not more than 1/3 of the flange width of the dimple, they can be stop drilled with a 1/16" drill bit as long as the edge of the stop drill hole wont extend beyond 1/2 of the width of the dimple flange.
  For cracks that are small enough so that a stop drilled hole would be right adjacent to the inner edge of the dimple, a small round jewelers file can be used to remove the cracked material.

Time Taken:     8.1 hours

Dates:                August 29 - September 4 2022

Rudder Total Time:                      41.7 hours

RV-10 Build Total Time:              89.4 hours

Priming Total Time:                     8.8 hours (not included in build time totals)