Wing doublers (4)

4 hours

I haven't touched the wings in ages, but my parents were visiting so I thought we could knock out a task that would take an extra set of hands.

There's a doubler for each wing, and I drilled all the holes back when I built the wings.  However, before they're riveted on they need to be trimmed to leave an appropriate gap along the sides of the fuselage.  The fuselage didn't exist the last time I worked on them!

Anyway, we rolled the plane into the driveway and installed the wings.  One thing I noticed was the Sonex instructions for installing the wings have you start with the right wing and insert the main pins back to front.  This works with the seat and/or floor removed, but once it's all closed up I won't have any access to the back side of the spar tunnel.  So I think for the B model we need to start with the left wing and insert the pins from the front.

We put the wings on and then started working on fitting the doublers.  I've seen a few methods online for clecoing the doubler on one row of holes over, and then making a jig to hold against the fuselage side and trace a line.  When cut to the line, theoretically the doubler will end up trimmed correctly once moved over to the correct row of holes.  I started down this path, but I realized that the row of holes closest to the fuselage and the next row over didn't seem to be exactly parallel.  Or at least the distance between rows was slightly different on the top and bottom, and forward and aft of the main spar.  I concluded it was too complicated to try and get a perfect line drawn without having the parts in their final locations.

My plan is to use the Van's wing root gasket anyway, which calls for a 3/16" gap between the edge of the wing and the fuselage.  That's a fairly big gap so it was easy enough to sneak up on it.  So what I did was cleco the doublers in place one row over, and trace an approximate line at a distance from the fuselage that I calculated would allow me to install the doublers in the right place without interfering with the fuselage.

I cut to that line, and then I was able to install both doublers in their final position.  Then it was easy to just create a jig to trace a new line exactly 3/16" away from the fuselage all the way around.  I cut to that line and that was it!

Here's what the Van's gasket looks like.  It's like a lower case 'h'.  I checked that a 3/16" gap would work and it looked about right.

Couple more pictures of the plane with the wings on before we put everything away.

It was starting to get dark by the time we were done so we called it a day and stashed everything back in the garage.  I'll rivet the doublers on later!

Cockpit Air Vents (4)

4 hours

There are a few options for getting fresh air into the cockpit.  I've seen some pretty nice Naca inlets ducted to eyeball vents, the snap-in windshield vents (which I have), and the RV-10 back seat vents.  I live in Texas at the moment, so I plan on flying in pretty hot weather.  Therefore I want all the air I can get!  I already did the windshield vents, but I've read that some lower-body cooling would be a big help.  Based on cost, complexity, and weight, I decided to install the RV-10 vents rather than Naca inlets with ducts and all the associated parts.

Vans sells all the parts needed to install these vents for about $20 a pair.  They're made for the back seats of an RV-10 which I think would have all the required holes already cut in the fuselage sides.  Even starting from scratch it was pretty simple to get these installed though.

I started by deciding where I wanted to place them.  I sat in the seat and just reached forward as far as I could without leaning forward, and made a sharpie mark on the inside of the side skin.  I figured I'd put it as far down as forward as I'd be able to reach with seatbelts on.  Then I drilled the doubler plate from the kit to the side skin, removed it, and clecoed it back on the outside so I could work from out there.

I traced the hole in the doubler on to the skin to give me an initial hole to cut out.

I cut this hole out, and then I was able to install the inner part of the door into the hole.  Then, I could trace the outer surface of the door onto the skin and enlarge the hole to match that.

Then the hole door fit in the hole with the outer surface nice and flush with the outside of the fuselage.

You can see here how the hole is now slightly larger than the doubler plate.  The door closes against the doubler and leaves it flush with the skin.

Here's the finished product:

Here's the inside:

And here's what it looks like open:

After that I repeated the whole process on the right side!

Hours Breakdown #5

Someone asked me at work how long I've spent on this thing, so here you go:

General/Misc:        16.0
Tail:                        72.0
Wings:                  147.5
Control Surfaces:   59.5
Fuselage:              196.5
Controls:                31.5
Landing Gear:        14.5
Windshield:            16.5
Canopy:                  30.0
Cockpit:                    7.0

Total:                       591 hours

Plus countless hours looking for hardware, mindlessly staring at the plans, searching the forums, and so on!

ELT Bracket (5)

5 hours

This is definitely something to take care of before riveting the aft fuselage floor in place.  In fact, for anyone reading this, an even better time to do it would be before the turtle deck is even installed!

Anyway, I will need an ELT eventually, but the plans leave you on your own for mounting it.  After a bit of research I decided I'd plan on using the ACK E-04 ELT.  However, ELT's and especially their batteries have a finite shelf life, and who knows when this plane will actually fly.  So instead of buying the whole ELT now I just bought the mounting tray that goes with it so I can figure out the mount now, and just strap the ELT to it later when it's closer to flying time.

I did what I've seen many others do, and planned to build a mount on top of the right upper longeron, behind the baggage compartment (in front of the aft seat belt mounting point).  This is a sturdy spot and still accessible for now.  I only riveted the aft floor around the access panel so far, so I was able to bend the forward half down and get a decent amount of room to work.

I started by just cutting out an arbitrarily sized piece of scrap sheet, with the angle of the aft fuselage side cut on one side of it (about 10 degrees).

Next I drilled that piece to the longeron and upper cross tie.  I added two pieces of scrap angle I had laying around as well.  This was an okay start.

 I also added a 1/8" thick strip to the top.

The mounting instructions for the ELT said it should not be able to move more than a tenth of an inch in any direction with 100 lbs of force applied.  I don't have a great way to measure that, but it seems pretty rigid.  From here I just pushed and pulled on it and examined where the mount seemed most flexible, and added reinforcements bit by bit until I couldn't really budge anything anymore.

I added two washers per screw to raise the tray up a bit, which will allow the mounting straps to clear the 1/8" thick reinforcement strip that I added to the top of my mounting sheet.

In total, what I added to the plane was 11 ounces.  Not too crazy, but I probably could have made it lighter with some less haphazard engineering I guess.

Here's what I ended up installing.

 In the plane!

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.