Tail Details (4)

4 hours

Wrapping up a bunch of little items in the tail area.  I cleaned up the clearances I filed on the rudder stops, and also replaced a few rivets on the stop plates with flush rivets to avoid any contact with the rudder.  Then I installed the rudder and safety-wired the hinge pin in place.

Next I filed some extra clearance into the hole on the right side that the rudder cable passes through.  The left side was ok, but I had to enlarge the right side quite a bit to avoid having the cable contact the skin.

According to the plans, you insert the ruddervator hinge pins in from the top.  But, if you do that, then once the stabilator tips are riveted on then you can't remove the ruddervators without drilling out all those rivets.  I know I'm going to eventually want to remove the ruddervators so I can paint everything, so I wanted to avoid that.

There's nothing blocking the hinge pins from going in from the bottom, so I tried installing them that way and didn't have any trouble.  The only concern then would be securing the pins so they couldn't ever fall out.  I talked to Sonex, and they said if I can secure the pins without interfering with any control surfaces then that should be fine.

So my solution to this was to replace the top two bolts on the tail post with drilled head bolts, and safety-wire the end of each pin to a bolt.  Now the ruddervators are removable without touching the stabilator tips, and the pins aren't going to go anywhere.

With that settled I went ahead and riveted the tips on.

Finally, I installed all the final ruddervator pushrod and rudder cable hardware, and then started working on the little fairings that cover the cables and pushrods.

The fairings are plastic and come in kind of a rough form.  A few minutes on the bandsaw and sander and they were ready to go.

I laid out a few holes on each one, then drilled them to the side skins.  I just used some leftover Avex aluminum rivets I had from the wing tips to attach them.  Of course I ended up being short exactly one rivet, so I'll come back to that last one later!

Trim System (3)

3 hours

Now that the tail is coming together I felt like seeing how this pitch trim system is supposed to work.  With the Y-tail, it would be complicated to use trim tabs, so the system uses two springs instead to just apply pressure to the elevator pushrod.  One spring is fixed, and pulls the stick forward, and the other one is adjustable and pulls the stick aft.

The aft spring is attached to the pushrod using this bracket and two hose clamps. 

I spent about 45 minutes making this thing, then realized it was supposed to be 1/8" thick, and I had used 1/4" aluminum.  I threw it away and re-made it out of 1/8" bar stock, which went a lot faster than the first one.

The other end of the aft spring attaches to the horizontal member just behind the seat (which I can't remember the name for... aft fuselage cross-tie?).  The plans show the end of the spring hooked through the top of this C-channel, but when I put the spring there it rubbed on the flap drive tube.

Instead of that, I decided to mount the forward end of the spring to the larger member just forward of that.  It has this extra duplicate hole next to the hole for the elevator pushrod that doesn't do anything, so that seemed like a good spot.

However, the force of the spring tension flexed the sheet metal a little bit there, which I didn't like, so I made a quick little reinforcement plate and riveted it in place.  I think this will do it.

At the forward end, there's another spring attached to the stick that pulls it the opposite direction.  This red bracket mounts to the back side of the instrument panel with a knob on the front.  Turning the knob clockwise shortens a cable, which increases the tension on the forward spring and effectively gives you nose-up trim.

This is full nose-down:

This is full nose-up.  The instructions say that you should be able to trim the ruddervators full up on the ground with the trim system, but this is as far as mine goes.  I will need to shorten this spring or buy a shorter one to increase the tension.  I'll work on that some more later!

Stabilator Tips (4)

4 hours

Here's a job I've been putting off since I built the stabilators a few years ago!  Ultimately, like so many other jobs I dreaded, it wasn't too difficult once I got started.  It was definitely easier than the fiberglass wing tips at least.

The fiberglass pieces that come with the kit are a bit too large.  The front edge is tapered, so the plans have you cut the bottom off the create to correct overall length.  I couldn't really come up with a good way to measure this, so I just snuck up on it.  I think I ended up cutting off about an inch on each piece.  I used a Dremel cutoff wheel and a belt sander to do it.

The closer piece in this photo is cut to length, and behind that is the other one not trimmed yet.

Next I laid out the holes and drilled each tip to its stabilator.

The other cut I had to make was the clearance on the aft side of each one for the ruddervator.  I carefully snuck up on this cut too, since I wanted to end up with a nice even gap between each tip and ruddervator.  Once I did the initial cut I just used the belt sander to remove a little bit at a time and did several test fits until it looked good.

Each tip gets a rib to reinforce the aft part.  They're the same ribs that are used in the ruddervators, with the forward edge cut off.  You might notice that on the lower assembly in this photo, the rib doesn't reach as far towards the aft point as the other one.  The fiberglass on that one was built up extra thick in the corner, which blocked the rib.  I just got it as close as possible, then cut the forward end of the rib off to make it even with the other one.

One final test fit, and then I riveted the reinforcement ribs in!

Ruddervator Rigging (2)

2 hours

Continuing on with setting up the tail control surfaces.  All I had to do here was set the lengths of the pushrods going from the mixer to each ruddervator.  In order to set the right length, the plans say to hold the stick all the way aft and set each ruddervator to 10 degrees up relative to the tops of the stabilators.

I used bungee cords to hold the stick all the way back, and then I made a 10 degree template out of a piece of cardboard.  That made it pretty easy to set each pushrod to the right length.

I'll have to take the stabilators back off again anyway because I still have to do the fiberglass stabilator tips, but now that everything is set up they're be quick to put back on.

Rudder Rigging (2)

2 hours

This was pretty simple.  I put the rudder on with its piano hinge and centered it, centered the control mixer, and then adjusted the cable lengths to keep both parts in the right place.

The only issue I ran into was the rudder drive horn interfered with the corners of of the stop plates at the bottom corners of the tail.  I filed some relief into the corners of the drive horn on each side to fix the interference.  However, the drive horn happens to land on the rivets on the stop plate instead of the flat surfaces of the plates themselves.  I'm not sure if that matters, but if it does I think I will just drill those rivets out and replace them with flush rivets.  I'll figure that out later.

You can see here where the drive horn was running into the corner of the stop plate:

I cleaned up that edge which also helped with the interference.

Working on filing relief into the drive horn:

It's pretty good now but I'll probably do a little more later.

Up front, the next task was to link the rudder pedals to the mixer by completing the cable adjusters I started earlier.  The plans say to put the rudder at the left stop, and the left rudder pedal 3/8" from the floor.  I used a 3/8" drill bit as a spacer, pulled the cable tight, marked it, drilled the hole, and trimmed the cable adjuster.  Then I centered the mixer, centered the pedals, and did the same thing on the right side.  I didn't have the right bolts on hand, but besides installing the hardware this part is done!

Ruddervators (9)

9 hours

Moving on!  The ruddervators were the same exact process as the rudder, flaps, and ailerons.

Annoyingly, the plastic coating on these two skins is something different than whatever's on all the other parts I've done so far.  It was SUPER hard to remove!  It's very sticky, but somehow also extremely fragile, so I couldn't really peel it off in big chunks.  I just had to sit there and pick away at it.  That covered like 2 tedious hours of the time I spent on these parts.

 

This bag used to be totally full!

Rudder (5)

5 hours

Holy crap it's been 6 months but I'm finally back at it!  I've been busy with house projects, work, and other stuff so the poor plane just sat in the garage.  It's time to get back to work!

Anyway I figured I'd start with a relatively simple part and bust out this rudder.  The drive horn plate needed a few degrees worth of bend.  I thought I had already bent all the plate type parts that needed bending, but I guess I missed this one.  I don't have my arbor press anymore but with a little finagling I got it bent acceptably with my little vise.

Next I cut out the skin.  Just like the ailerons I used snips to carefully cut it to the lines.  Pretty easy although I sliced the crap out of my hands, also just like the ailerons.

I fit everything together, which was simple.  The plastic cap at the top didn't fit that great at the tip, but there wasn't much I could do about it so I just got it as close as I could.  I might add some filler later, or more likely just leave it!