Tailcone Priming and Final Assy. Started

Boy there are a lot of parts to prime in the tailcone. It took several sessions to finish all of the priming. I started by doing the skins, and then 2 additional sessions to do the remaining smaller parts. On most parts I take the blue protective coating off of the part the first time I start to work on it. With the skins, I’ve been leaving the outer blue protective coating on until later in the process to help prevent scratches. Upon removing the coating from the side skins, I found a bunch of surface corrosion starting. Nothing too terrible, but enough that some spots took a lot of elbow grease to sand off. I mostly used a maroon scotch brite pad, but a couple of stubborn spots needed a little fine sandpaper to go a bit deeper, followed by more scotch brite to get it completely off. I then sprayed the areas with some rattle can self-etching primer to help protect it for now.

Lots of these corrosion spots on the side skins
After a little scuffing
Mostly all gone

This picture will give you an idea of how many spots there were to deal with.

Pile ‘O Primed Parts
Initial Couple of Parts Assembled
Bulkheads Riveted Together
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Getting Ready to rivet skins to stiffeners

 

McRiblets

I spent a few hours today finishing the bend to the new elevator trim tab skins and fabricating small ribs (riblets) to close out the ends of the trim tabs.

I think they came out really well. The first one I did came out fine, but was a bit of a test on exactly where to bend on my marked line to get the proper part width/flange length. I then was able to bang out the 4 riblets that I needed to make. Two outboard and two inboard riblets. The outboard riblets somewhat interfere with trim tab horns, so I made the flanges a bit longer to share holes and ensure proper edge distance.

I took the following pictures to document the process.

Started with a wooden wedge (oak) that I had previously made when trying to bend the tabs per the plans as a template against scrap trim tab skins.
Traced the outline of the wedge, marked the top and bottom cuts, and make a 20/32″ outer mark for the flange width.
Cut along the outer lines with snips.
Marking the position of the spar on the bottom skin and transposing that line to the riblet
Using a punch to locate the hole to be drilled
Drill a hole to serve as the relief for the flange separation
Snip out the metal on the tangent lines of the circle creating a separate flange piece that can be bend in more to accommodate the extra layer of metal of the spar.
Bend along the marked lines with a hand seamer.
First flange bent
Spar flange bent
Done!
Pretty good fit!
All 4 riblets completed. I used a 20/32″ flange for the inboards and a 28/32″ flange for the outboards to allow for hole edge clearance.
Marking out new holes that I will drill in the skins to rivet the riblets in place. 3 new holes will be added between the notches in the skin.

All-in-all, I’m very happy with how they came out. These were really the first true part that I’ve had to fabricate from scratch on my own. It really wasn’t as hard as I had anticipated, and it’s satisfying to see it come together. I can tell already that I’ll be very happy with how this turns out compared to my barely acceptable bending of the tabs.

Upper Tailcone and Elevator Trim Tabs take 3…

Since the last post, I’ve completed putting together the tailcone structure and match drilled everything. I’ve subsequently taken it all apart and deburred all holes and any remaining edges.

Looks like an airplane part!

Rear Seat Belt Anchor Point

 

Pile of deburred parts

In the meantime, I wasn’t completely happy with how my elevator trim tabs came out, so I got new parts to re-do them. The 2nd time went worse than the first.

The goal here is to bend the tabs to close out the ends of the trim tabs. It seems like it should be relatively easy!

elevator-close-outs

I didn’t have trouble bending the tabs on the skins, but these have given me trouble.

After messing up the first bend of my second attempt, I went off to do some reading on VAF. It seems lots of other have also had trouble with these tabs, so I guess it’s not just me. I also realized that I didn’t use any adhesive on the blocks so they moved slightly while attempting to bend the tab. Once I used some double-sided carpet tape, the next attempts went a little bit better. Probably passable, but I had already managed to crack the skin during my first bend.

Badly dented and cracked skin
Another attempt with tape. Better. Probably passable, but not the greatest.
Wavy!

The first set of trim tabs I attempted are shown below.

Bit of a buldge

Below is yet a 3rd set of new skins for the trim tabs. After doing some reading, I’ve decided to do what others have done, and that is to cut off the tabs and fabricate small riblets to put on the ends instead. It might take me a few tries to get those correct, but I have lots of scrap trim tab metal to work with.

3rd set of skins😦
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Plan to fabricate something like this instead.

 

More Tailcone

Making decent progress on the tailcone. I’ve got the lower structure completed and match drilled. Starting to work on putting the top skins on now. Getting close to taking everything apart to do some massive deburring.

I’ve also placed my order for the Quick Build Fuselage. Initially, I was thinking I would slow build this part, but have since decided to order the QB. I didn’t do it the standard way in terms of ordering both the QB wings and fuse at the same time, but that should be fine. It also helps spread out the money outlay a little bit.

My wings are currently scheduled to be shipped in January. Fuselage in April. I should have plenty to keep me busy between now and January. I still have to finish the tailcone, attach the entire emp together, and do the fiberglass fairings. That should keep me busy until the wings come. Then I’ll have some stuff to work on with the wings prior to getting the Fuse a few months later.

 

Starting to put the bulkheads on the bottom skin.

A video of me match drilling one of the bottom J-Channel Stiffeners.

Right side skin attached
Center line on J-channel stiffeners showing through the skin holes to make sure of proper edge clearance when drilling. 

Then I realized I had made a mistake. I had aligned one of the J-channel stiffeners to the wrong starting hole. Oops.

I had actually discovered it when I was checking to make sure that the aft end of the stiffener was captured by the tab in the bulkhead. Clearly it wasn’t.

So what I did was to slide the stiffener down and align the first drilled hole with the hole it should have aligned to. The end result was I had to drill extra holes almost equally spaced between the existing holes along the entire length of the stiffener. This worked well. I ran it by Van’s and got their blessing as well just to be sure the extra holes wouldn’t compromise the stiffener too much.

Shows the first hole in the stiffener aligned properly now. You can see new holes need to be drilled about equidistant between the existing holes in the stiffener. 
First couple of extra holes drilled. 
Starting to look like a real airplane piece
View from the front end looking back.
Aft deck on and aligning the longerons with clamps
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Flipped on its side to match drill the bottom holes

 

Start of Section 10 – The Tailcone

The elevators are done with the exception of the trim tabs… Well the first iteration of the trim tabs anyways. The main mistake I made on the trim tabs was bending the close-out tabs on the end too close to the reliefs in the skins. I misread the directions and thought I was supposed to put the supporting wooden blocks 1/32″ to the inside, when really it was in the opposite direction. The end result is some bulging as you approach the ends of the tabs because the tabs are too long. Not real terrible, but I’m just not happy with how they came out. So parts are on order to build new ones, which won’t take more than a few hours to complete.

Testing the trailing edge bend of the trim tabs
Bending the close-out tabs (wood blocks placed too far inboard)
Trim tab hinge in place and match drilled
Proseal curing…

So for now, I’m on to Section 10- The Tailcone.

Rear tie-down anchor point

Tailcone floor plus lots of parts prepped in the background

Elevators getting close and a new compressor.

I bought a new compressor to give me some more capacity and be a little quieter seeing it’s in the garage with me. I decided to get a 2 stage, 60 gallon model from Harbor Freight. It refills very quickly now and is much better when running the air drill or spraying primer.

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New Compressor

Since the last post, I’ve made a lot of progress on the Elevators. Below are some pics documenting the process.

I had a nice day to move the priming outside for this round. I used an old grill top from my pig roaster that I never use to provide a better backdrop for the spraying. Previously, smaller parts would really move around, flip over, etc… I figured it was because I was spraying against a hard surface and not something that the air from the spray gun could blast through. Happy with the results. The setup is shown below with all of the parts laid out (minus the skins)

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Priming parts outside for the first time.

Various pictures of initial riveting of the spar and spar stiffeners, trim access stiffener and nutplates, stiffeners back-riveted to the skins, and pop riveting the ribs in some tight quarters.

A video of me using the special RV-10 Emp bucking bar that I bought with my toolkit to rivet the rear spars

Most riveting done.

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My rudder trailing edge came out okay, but I wasn’t 100% happy with how the joining of the skins came out using the VHB tape. Seeing the foam ribs are attached to the skins with Proseal, I decided I would also use the proseal for the trailing edge as well to see how it goes and compares with the VHB.

 

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Foam ribs with paper templates attached. Ready to cut.
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Messy stuff
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Both Elevator Trailing edges done

I also decided to use the steel bars I have and match drill them to the trailing edge holes so the clecos end up holding everything tight to a straight bar.

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Right Elevator set and ready to spend a few days curing

I then spent some time riveting the trim covers and trim attachment brackets together, along with marking and trimming the counterbalance weights.

 

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Now to wait a few days for the Proseal to cure. In the meantime I’ll start working on the trim tabs.