Category Archives: Tail

Tail installation and control stops

Ground a few spots on the elevator control horn to allow full up and down elevator motion.  It was contacting in a few spots on fittings in the rear fuselage.  Also had to grind a little on some aluminum angles to allow clearance for the pushrod.  I decided to make a small deviation from plans and add an upside-down T-shaped piece of aluminum as a solid stop.  Otherwise I was going to end up with really tight clearances all over the place.


Below, I have the elevator at full down travel with the horn hitting the other stop.  It’s hard to see the stop in this picture, but it is just above the reflection on the black powdercoated elevator horn.  I was pretty anxious about this stage of the project, so I kept putting it off fearing I positioned the tail so horribly I would never be able to get full control deflection.  It was certainly a tight fit, but I’m extremely happy with how it turned out.


I ended up using AN3-5 bolts instead of AN3-6 when attaching the rear spar of the vertical stabilizer.  The AN3-6 were so long they required 3 washers apiece which seemed like overkill.


These three bolts connecting the stabilizers together required nutplates since access to the nut side is almost impossible.  I’m extremely happy with the tight and solid connection.


Attaching tail to fuselage

When attaching the horizontal stabilizer, it is important to be sure the bolt holes will go through the angle beneath the longerons with enough room for the nuts to clear the leg. I checked the measurement and though I had more clearance then I ended up with–I may have got lucky.  I did have to remove one rivet  and install it from the other direction to prevent interfering with the nut.

I had to cut probably about 1/16″ or so off the stabilizer skins to get them to fit around the turtle-deck (as directed by the plans).

The vertical tail was a tight fit.  I had to trim some of the rear turtledeck to allow for clearance of the spar attachment when installing it (the notch called for in the plans would work if you could magically teleport the tail into position).

It seems my hardware kit was missing two bolts for the horizontal stabilizer and all the nut plates for the vertical tail.

Horizontal Stabilizer Skinned

I thought it would be fun to have my friend Archie help rivet the stabilizer skins.  I got all the holes deburred and ready for riveting and had him come over one evening.  He ended up riveting most of the right stabilizer.  We had a good time with him telling some of his experiences aboard the USS Dunlap during WWII.

Attaching the hinges to the elevators and stabilizers and getting everything to line up seemed scary, but I was careful and everything worked out as perfectly as I could hope for.  Having it assembled and laid out on my 4’x8′ workbench really gives me an appreciation for how big this is (even if it is a small plane).

Horizontal Stabilizer Skinning


I started skinning the horizontal stabilizer.  Turns out I didn’t pay attention to what side was “up” and drilled all the holes for one side and had it clecoed on.  The next day I was thinking about it and realized I had a 50/50 chance of having it backwards.  Fortunately I got lucky.  Since both skins were laser cut, I THINK I could have simply switched them around and all the holes would have lined up, but I am very glad I didn’t have to.

It is a great feeling seeing the skin line up with all the ribs that were previously laid out.


Vertical Stabilizer riveted

I riveted the skin to the vertical stabilizer and built the rudder.  I decided to polish the skins while I was at it.  They seem like they need some more work, but I’m pleased with the results so far.

Vertical Stabilizer Skin

I have attached the vertical stabilizer skin with clecos and drilled most of the holes to the final size.  I also attached the piano hinge for the rudder.  I need to disassemble and deburr, but should be ready to rivet it soon.

I noticed a laser cut part on the rear spar with edges that looked like they weren’t totally deburred.  It seemed like it would probably be fine–I couldn’t really catch my fingernail in any of the bumps, but I knew it would bother me.  I ended up drilling out the stainless steel rivets.  This was a huge chore with my HSS (high speed steel) bits.  Apparently I need to get some cobalt bits as they are good on stainless steel.  I don’t have enough rivets to finish the job and will need to order more of that type from Sonex.  Notice the empty holes.

First rivets

I decided to pull my first rivets.  I hand riveted the forward and rear tail spar and most of one elevator.

Here is the horizontal stabilizer from another angle.

Caroline was sympathetic about how much work pulling the rivets by hand was, so she let me get an air compressor!

The Harbor Freight air hydraulic riveter made quick work of the elevators and both are now almost complete.  I read the instruction manual for the riveter and was led to believe I needed to disassemble it and add oil.  Then the rivet gun didn’t work at all.   After searching the internet it seemed everyone who disregarded the instructions had no problem with the gun, but those who added oil had the same problem as me. Notice how the reviews on the Harbor Freight website are unusually hight–9 ratings for an average of 5/5 stars.  I bet these people didn’t disassemble it to add oil, or they just knew what they were doing :-)

While searching the internet for help, I found this amusing piece of advice about not adding oil.  Since this is a “hydraulic” riveter and not simply a pneumatic one, it is clear that oil is actually required in the riveter.  The trick is making sure you add it in the right place and not too much or too little or it won’t work correctly.  I now believe it comes ready to run right out of the box.

After spending 3 hours messing around and totally disassembling it, I realized I had added too much oil and was able to determine the correct amount.  I expect it to last the entire project now that I figured it out.  I operate it at ~45 psi and it is fantastic.  By tuning the pressure I can have the stem break off in one or two trigger pulls.  I prefer two.

Here I am demonstrating to Caroline how much harder the hand riveter is.  From the look on my face, it looks like I am right in the middle of the final stem-breaking squeeze.

Here are both of the mostly-completed elevators.

Left Elevator and Hinge

After figuring out a workable method on the right elevator I thought I’d show some pictures of my method on the left one.  First I cut reasonably close to the line with my bandsaw.  Then I trim up to the line with these offset Wiss snips.

I cut the corners with my Dremel tool.

I do the holes for the ribs using my handy rivet spacing tool.  There is a warning specifically saying not to drill through those holes (use it as a layout tool instead), but I have totally disregarded the warning.  Hopefully whatever bad outcome I receive by disregarding the warning is offset by all the time I save.

I also attached the hinge to the right elevator.  This needs to be positioned such that it will line up with the rest of the horizontal stabilizer when it is riveted together.  My yard stick seemed to be just the right thickness to use as a spacer and get everything lined up.

Horizontal Stabilizer and Right Elevator

I hear it is important to have photos in the builder’s log of myself building the airplane, so Caroline volunteered to come down and take some pictures.  I drew an outline of the horizontal stabilizer on my workbench and here I am precisely positioning the forward spar.

While we are at it, here is the vertical stabilizer.

I am still trying to decide what to do about corrosion protection, so I have been too chicken to start riveting.  I decided to start working on the elevators–I have been worried about how to cut the control surfaces with the tight bends.  I ended up cutting within an inch or so of the line with the bandsaw since it is difficult to see how close to the line I am on the bottom side.  Then I used offset Wiss snips to cut close to the line.  The Andy snips seemed to big for this job except on some of the long cuts.  I used my Dremel tool with an abrasive disk to cut through the bends.  Then I used the  scotch brite wheel to shape right to the line.

I started drilling pilot holes in my first piano hinge.

Horizontal Stabilizer

I went about a month with no progress on the airplane.  It was mostly due to it being the last month of my master’s degree.  I decided to start working on the horizontal stabilizer while I decide on what type of corrosion protection to use before I finish the vertical stabilizer.

Here I have the forward and rear spars along with the ribs I mostly prepared about a month ago.  For some reason the ribs are my least favorite part, so I forced myself to make them all one evening rather than postpone them repeatedly.