Pitch Trim Adjustment (2)

2 hours

I noticed when I installed the pitch trim system that it didn't give me nearly enough nose-up trim, so now I'm back to try and address that.

I had what I thought was a great and simple solution, and that was to drill a new hole in the stick A-frame part that the forward spring attaches to.  I thought that moving the hole up would give the spring more leverage on the stick, which was true.

You can see here the new hole I drilled with the spring installed, and the old hole beneath that.  This did greatly increase the force of the nose-up trim!

I thought I was done, until later I was goofing around and noticed that with the stick fully aft, the aileron bell crank attached to the stick runs into the spring with it installed in this higher position.  This is obviously not acceptable, so I had to move the spring back down and figure out something else.

It was clear I needed to shorten the forward spring to get more tension out of it, but I had a hard time figuring out a good way to trim the spring and bend a new hook on the end without totally mangling the whole spring.  I scratched my head over this for a while, and eventually I discovered a method that actually works really well.  So here is how to do it.

First, decide how many coils you want to remove from the spring, and jam a small screwdriver through, like this:

Next, run a larger screwdriver through the middle of the spring, and wiggle it around the side of the small screwdriver.  This will create a gap between the coils you picked to remove.  Now you can grab the coils at the end with a pliers and bend them away, while keeping the rest of the spring straight with the big screwdriver.

Here's what it looks like with the coils bent 90 degrees.

Finally, to remove the extra coils, I carefully ground a little groove into them with the edge of my bench grinder wheel.  That created a weak spot, so then I could grab each coil with the pliers and just bend it off.

I removed two or three coils at a time, testing the system between each adjustment.  Here's how much I ended up removing!

This made a big improvement, but it seemed like it got to a certain point where continuing to shorten the spring didn't really make much difference anymore.  I finally decided to go back to my "extra hole in the stick" idea.  I drilled one more hole between the original and the extra hole that I added earlier.  I also made sure to install the spring so the main body of the spring was below the hook at the end instead of above.  This finally worked.  Now I can trim the ruddervators just about all the way full-up on the ground, and the aileron bell crank does not hit the spring at any point.  Finally!

Tail Fairing Attachment (1)

1 hour

I did not like how the plans called for attaching the stabilator fairing with nothing but sheet metal screws, especially around the curved part at the front.  I definitely needed a way to pull the front part tight, and threading into the annealed fairing with a sheet metal screw I'm sure would yield close to no clamping force without stripping out.

I ordered some single lug nutplates and installed them on the fairing.  This allowed me to screw the front end of the fairing tightly in place, which helped it to match the curve at the back of the turtle deck.  It's not perfect, but I think it's good enough at least for now.

 Next I drilled the rest of the holes through the fairing and stabilator.  The plans called for #4 sheet metal screws for these holes, which I installed.  Unfortunately, they all stripped right out!  So that didn't work.  I'm going to try larger sheet metal screws, and if that doesn't work I'll just install nutplates like I did at the front.

Brakes, Throttles, and Cockpit Side Panels (7)

7 hours

I wanted to use up some more of the parts I've had sitting in boxes for a long time, so I went ahead and tackled the cockpit side panels and installed the brakes and throttles.

My initial thought was I'd mount the brake master cylinder and handle, and then run the lines, set up the calipers, and bleed the brakes so the whole brake system would be done.  I got most of that done but then realized that the brake lines go through the cockpit floor, and I don't want to rivet that thing on yet, so there wouldn't be much point in running the brake lines for now.

Anyway, I started with the brake calipers.  I had the calipers just slipped over the axles way back when I installed the landing gear and wheels, but I had to pull them off to fit the backing plates.  I didn't get a good picture of it, but I used a method I saw on Ryan Roth's blog for using a hose clamp around the gear leg to create a little jacking point.  Here's a link with some pictures.  I jacked the plane up like that and worked on one side at a time.

To install the calipers, you sandwich the backing plate between the caliper and the inboard side of the axle, and then a clevis pin goes through the caliper, plate, and a small tab welded on the bottom of the axle.  The pin prevents the plate and caliper from rotating around the axle.

I'll start by saying that the holes the plans direct you to cut out of these backing plates don't make much sense.  I made the first one according to the plans and it didn't fit at all.  All you really need to do to the plate is enlarge one hole for the clevis pin, and create an opening for the hydraulic fitting on the caliper to go through.

I made the first plate per the plans, and once I installed it on the plane it somehow oriented the plate and caliper like 45 degrees off of horizontal, which didn't seem right.  I checked the plans page for the wheel pants, and the depiction there had the backing plate pretty much horizontal.  I ended up just flipping the plate, and mocked it up with the caliper on the axle with everything approximately horizontal.  One of the existing holes on the plate was very close to lining up with the welded tab on the axle as well as one of the four mouting holes on the caliper.  That seemed a lot more reasonable.  On top of that, the hydraulic fitting that I had cut a large hole for the first time was nearly coincident with the existing large round hole on the plate, so all I had to do there was enlarge that hole a bit, and then everything fit pretty well.

At the bottom of the plate is the first hole I cut for the caliper fitting, before I flipped the plate and started over.

Plate and caliper installed right-side-up.

The four nutplates will be used for mounting the wheel pants later.

When I did the other side, I started by mocking everything up on the axle before cutting anything.  This plate ended up being a lot less butchered to achieve the same result!

Here you can see the welded tab on the axle.  The last thing I did on each side was run a 1/4" drill bit through the caliper, plate, and tab to make everything line up.  The caliper already had a 1/4" hole, and the plate and tab just had to be drilled out a tiny bit and then everything fit.

The hole for the fitting on the right was originally a round hole; I only had to enlarge it slightly to make it fit.

 Next I installed the pistons and brake pads into the caliper.  I used a C-clamp to press the pistons in.  I put the first one in dry for some reason, which I do not recommend!  It was very tight and I don't think I'll ever get it out until I pressurize the brake lines.  On the other pistons I lubed the o-rings with a tiny bit of brake fluid and that helped a lot.

Finally, I packed all the wheel bearings with grease and reinstalled the wheels.  I still need to drill a hole in each axle for the big cotter pins, but I'll do that later.

Inside the cockpit, I installed the bracket to the forward wing attach angle per the plans.  The master cylinder bolts to that bracket, but I don't have the correct hardware yet, so it's just temporarily installed here with Home Depot bolts.

After that, I wanted to install the throttles.  However, I knew they bolted to the wing attach angles but I wasn't sure how high to mount them.  I realized that the plastic side panels that came with the kit each had a bulge to accommodate each throttle, so I decided to fit the side panels first and then base my throttle locations from there.

The side panels came in two sheets and needed to be cut out and trimmed to fit.  Here's an example of what one of the forward panels started as:

I started with the left rear panel, and just trimmed and test fit over and over until it seemed good.  The contour on the bottom matches the seat pan, so I pretty much assumed that area was fixed, and just trimmed the top, front, and back to fit.  It took a while but wasn't too difficult.  To attach the panel, I drilled the top edge of the panel to the upper longeron.  This held the top of the panel in place, and I think the upholstery will retain the back and bottom pretty well.

Once I had the rear panel looking good I continued with the little forward panel.  This panel has the bulge that blends around the throttle, so I used that as a reference to place my throttle lever on the wing attach angle.

After many test fits I went ahead and drilled/clecoed the throttle in place.

Here's the let side trimming complete.

Here's the untrimmed right forward panel versus the finished left side for comparison to how it started.

Same thing for the rear panels.

Here are what the two throttles look like.  The left throttle accepts two cables.  One will go to the carburetor, and the other one drives the right throttle, so they move together.  The right throttle only has the one cable attached to it (from the left throttle).

The instructions say to install these cable retainers with a lock nut on each, but I found that the holes were way too close together for the lock nuts to fit.  I found I could get them plenty secure without the lock nuts, so I went with that.

Here's the left side throttle plate installed with the panels in place and the canopy closed.  Everything fits well!  I copied the Sonex factory plane I saw at Oshkosh and drilled an extra hole in the plate to store the canopy locking pin.  This has an extra benefit, I realized, in that the pin blocks the throttle lever from going all the way forward.  So if I ever forgot to install it, the pin should be right there and it would block the throttle, making it very obvious on takeoff roll that I forgot the pin.

Here's the right side plate.  I installed both plates for now without the throttle levers, since I have nothing to connect them to, and they'd just get in the way or get bumped as I work on other stuff.  So for now the levers and cables are going back in the box.

A couple more pictures of the completed panels.  To attach the top edges, I drilled and tapped the holes I put in the longeron, and used some black coated 6-32 screws.

At the interface where the rear and forward panels overlap, there's nothing behind the panels to screw into.  I found these plastic rivets at Lowes that work really nice.  The outer part pops through a hole, and then you screw in the inner portion which expands the first part to hold everything snug.  I put two on each side and they were good to go!

Here's the part from Lowes.  You get two of them for about a dollar.

Tail Fairing (3)

3 hours

The tail area is getting pretty close to complete, but one of the big items remaining was this fairing.  This is a piece that just covers the area between the two stabilators.

I started by laying out the flat pattern per the plans and cutting it out.

Since this part is not structural, I did what a lot of builders do and annealed the sheet metal to make it much easier to form into shape.  The technique that seems to work for this is to draw all over one side with a sharpie, then heat the metal from the other side with a torch until the sharpie disappears.

Once it cooled down, it was indeed very easy to bend.  It's kind of like a thick beer can.  Anyway, I bent the flanges first, using the edge of my workbench as a straightedge.  I could easily bend the flange down with nothing but my hands, and then I used a rubber hammer to pound it nice and flat.

Next I applied the curve.  The bottom of a 5-gallon bucket was about the right size to form the big end, and an aerosol spray can was the right size for the small end.  The area in between just kind of worked out once I got each end curved.

The part turned out pretty nice, but unfortunately it was just a bit too wide to mate up with the aft end of my turtledeck.

The part was easy to make, so rather than mangle this one trying to force it to fit I just started over.  This time I made a quick template out of a strip of cardstock to figure out how wide the big end should be.  I came up with 270mm, which is about 12mm narrower than the first part.

I made a new fairing, which went much faster then the first one, and the fit ended up much better.  I still need to figure out fasteners to attach the fairing.  The plans just call for sheet metal screws, but I think I will use small nutplates at least on the forward end where the fairing fits under the turtledeck.  I want to be able to tighten the screws there decently tight to hold the fairing inside that curve, and the annealed metal is so soft I think sheet metal screws would just strip out pretty easily.  So I'll come back to that.