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Right Rear Spar Doubler and Reinforcement Fork

September 8, 2010

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The next step on the rear spars is to trip the W-707D and W-707G Rear Spar Doubler and Reinforcement Fork to size.

These parts are shared between the RV-7 and RV-8 (and maybe more, I’m not sure), and must be trimmed if you are building the -7.

This is a tricky trim job, though, because many people have future troubles with drilling the rear spar to the fuselage and maintaining the required edge distance for the hole in THESE PIECES.

It would be best not to overtrim, and leave even less margin than what is already there.

The plans and construction manual both point to Dwg 38, which is of course not included as a full-scale sheet in the wing kit, so I got out my preview plans and started staring.

Even though I’m only working on the right side for now (will bring the left wing up to the right side’s progress when I get the replacement spar from vans), I’m going to do both sides of this now while I’m all mind-prepped to do it.

A snapshot of the applicable portion of Dwg 38. Looks like I should start measuring and marking. (No cutting yet, though!)

Keep in mind here that you measure from the edge you are about to start cutting away, so once you start cutting there is no double-checking your measurements.

Of course, I'm being dumb by doing the right side first (left is shown in the drawing above.)

Here are both lines drawn, measured, double-checked etc. It's still all making sense, so that is a good thing.

The bottom cut off. (For you OCD types, I realize I should have made the other cut first, which would have been a little less cutting overall, but oh well).

I decided to cleco the two smaller pieces together first, then transfer the lines to the bigger forks, and do those separately.

Ready to transfer the lines.

Of course, I didn’t get any in-progress shots of the fork cutting, but it went well. I then clecoed the left and right assemblies together and grabbed this shot after a few passes on the scotchbrite wheel.

At the end of this project, I am going to go back and count how many toes ended up in all the pictures. Here's...{counting}...6 more.

After some time on the scotchbrite wheel, I have two ready-to-cleco parts.

Nice and scuffed.

Then, I clecoed the doubler plate and reinforcement fork to the right rear spar and started matchdrilling.

Matchdrilling.

I had a hard time deciding if I should enlarge some of the rib attachment holes in the fork and doubler plate to final size, and I decided I would. I couldn’t find anyone who said it would be a bad idea, and now I’ll get to deburr and prime all of the rear spar components.

I did leave the majority of the rear spar “future” holes alone, though. I guess per the directions (indirectly, just in step order), I’ll drill those after priming the rear spar.

Here's a picture from the backside (actually, front side) of the spar.

Of course, I was careful to mark and enlarge to #40 the flange holes that need to be dimpled now (the reinforcement fork prevents the female side of the dimple die from getting behind these holes).

I didn't actually dimple, though. I need to leave something for tomorrow.

After taking everything apart and deburring holes, I have a few pieces ready for priming, and a rear spar with some remaining deburring before priming.

I scuffed the rear spar where I had already drilled and deburred to help remind myself what I have left to deburr.

Today’s hour was a good one; a few things ready to prime, and just one deburring and priming session away from being able to rivet the rear spar assembly together.

I need to go buy some more Napa 7220 Self-Etching Primer.

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Preparation for Left Elevator Skin Riveting

July 21, 2010

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Now that my #10 dies are here, I can proceed with the counterbalance skin and preparation for riveting.

This is how #10 dimples are supposed to look.

No cracks!

After beveling the exterior of the counterbalance skin, drilling the two fairing attach holes (that will be doubled up with the elevator skin) to #28 and dimpling to #6, I threw the counterbalance skin and the little trim riblet up on the priming table, opened the garage door, got the respirator out, and shot these two with primer.

Primed.

After that was done, I clecoed the counterbalance skin in place and riveted the two rivets on each side that can’t be reached after the skeleton is inserted.

There's a nice lap joint there that could have used some edge-rolling, except I FORGOT TO EDGE-ROLL, EVEN THOUGH I JUST BOUGHT AN EDGE-ROLLING TOOL!

The two rivets in question on the top.

Nice shop heads.

And two more on the bottom.

Then, before inserting the skeleton, you loosely place the counterweight in position and partly insert the two screws.

Okay...

Then, I riveted the little riblet I made to the trim spar.

Skeleton, ready to be inserted into the skin.

Closer look.

Of course, I then realized that I needed that area open so I could attempt to buck the four rivets outboard of that point. Drilled out that rivet.

At least I remembered to put some RTV along the back edge of the stiffeners.

After that, I got the skin clecoed on.

It's looking like something that slight resembles an airplane!

Another angle.

I’m kicking myself for not edge-rolling that one lap joint. I only remembered that I didn’t when I woke up in the middle of the night. My two options are to leave it, or drill out 4 rivets and edge roll. Maybe I’ll rivet the rest of the joint (two more rivets), then decide whether it is bad enough if the edge picks up at all. I don’t think it will, but I’ll start there so if I have to take it apart, it will only be a few rivets.

1 hour. 4 rivets, one drilled out.

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Left Elevator Counterbalance Skin

July 13, 2010

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A short half hour tonight. First thing was to grab the primed end ribs and get them clecoed to the left elevator spar. No problems there.

Looks good. Ready to rivet (but not tonight).

Next, I need to get the counterbalance skin taken care of (must be riveted to the skin before the skin can be riveted to the skeleton).

You can see I clecoed it in place and drew a line where the two overlap; I'll use this as my primer line.

Then, I realized I’m going to have a hard time deburring, dimpling, and scuffing with the blue vinyl on. [sigh] Off with the vinyl, re-cleco, redraw my line, then back off to deburr, dimple, and scuff.

After dimpling with tank dies where the skin sits under another dimple, and regular #40 dies where it doesn't.

While I had the #6 dimple die out (I’m attaching all fairings with screws for now), I moved over to the elevator skin and dimpled there, too.

Make sure you drill all holes that need to be dimpled with the #6 dies to #28 drill. This is slightly larger than the #30 you are used to.

Again (for the search engines), the correct drill bit size for a #6 screw and #6 dimple die is #28. Ask me what happens when you dimple a hole that isn’t drilled to the right size. (Hint: the same thing that happens when you overdimple using something other than a dimple die because you are too cheap to buy a #10 die…see below…)

Okay, back to the counterbalance skin.

These are dimpled to #8 (I don't have a #10 dimple die). last time, I used a punch set (with a little rounded lip on it) to enlarge the dimples to the equivalent of #10 dimple die.

Let’s countersink the counterweight as a female dimple die.

Looks good.

Uh oh. I went a little far with my makeshift die. I stared at this for approximately 0.0000001 seconds before realizing I had to scrap the part.

See the ginormous cracks? Yeah. Not good.

A closeup of the other one. Oops.

So, the reordered part count is up to 2.

I’m not worried, I have some other stuff I can be doing while I wait for a replacement counterbalance skin (E-713, $8.85) from Van’s. Also, I immediately put in my order with Avery for a #10 dimple die (along with some clecos, an edge roller tool, and some more drill bits).

USE THE RIGHT TOOL FOR THE JOB, ANDREW!

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Riveted Elevator Horn and Trim Tab Spar

July 7, 2010

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I don’t really love working in short bursts like this, but I do what I have to. Let’s do the elevator horn tonight.

I first clecoed every other hole. The left elevator horn was actually easier to cleco on than the right. I can't figure out why.

Anyway, a few loud noises later, and I had the first six done for the day.

Nice shop heads.

And again, a few minutes after that….

Six more, for a total of 12 so far.

Then, I convince the girlfriend to come outside and try her hand at squeezing.

Looks great.

She did great, but one of the rivets split diagonally as it was squeezed. It wasn't her fault, but I'll have to replace it tomorrow.

14 rivets. 0.5 hours.

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Started Riveting Left Elevator Skeleton

July 5, 2010

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After the last couple work sessions priming various parts, I was getting all hot and bothered to rivet something. I thought I would tackle the spar reinforcements. I also forgot to charge the camera battery, so I’m using the new phone. Hopefully they turn out okay.

Here's the left elevator spar and reinforcement plates.

I got out a few rivets. AN470AD4-5 and -6.

Let's get riveting.

I clecoed the reinforcement plates and nutplates onto the spar, and riveted the four corners and one ear of the nutplate, then took out the clecos and riveted the rest.

The tape is a trick I have been using out of vanity. The rivets look better when they haven't been marred up by the rivet set.

After doing both plates, I put the spar back on the table.

Pretty.

And just to show you AGAIN how much I love my new tungsten bucking bar, here are the perfect shop heads.

The inboard shop heads.

The outboard shop heads.

Next up is to continue riveting on the skeleton, so I pulled E-705 out of the “recently match-drilled” pile and got it deburred, dimpled, edge-finished, and prepped for priming.

Ready to prime.

This is the other side after being shot with primer.

16 rivets set in 30 minutes of building after 30 minutes of shop cleanup (cleaned out the shopvac, etc).

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Trim Tab Fitting

July 1, 2010

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Okay. Today was a pretty productive day. I had taken everything apart, then realized I still had some more fitting to do on the tab, so I put it all back together again. Before that, though, I thought and thought about what to do about the two holes on the right side of the picture. These are for the fiberglass tips, and they are supposed to be matchdrilled later, after the counterbalance skin is installed as a lap joint underneath. How can I deburr parts that are riveted together if I drill through both? Maybe it’s not a big deal, but I decided to drill them to #30 now (for #6 screws).

Two holes the right before drilling...

...and after.

Then, I was thinking ahead about the safety wire trick you have to do with the hinge pin. Why not drill that now, so I can deburr before priming?

I drilled this just larger than 0.060, which is one of the biggest safety wire sizes.

Next, time to deburr and dimple the left elevator spar.

Me dimpling.

And after everything was dimpled, a nice picture down the spar of my blurry recycling bin, golf clubs, and motorcycle jack. (No motorcycle anymore, but the jack comes in handy to lift the corner of a car when a tire needs to be taken off for one reason or another.)

Spar! (I'm tired, so we are down to one word captions for the day.)

Another shot of the same.

Dimple! (Wouldn't it be annoying if I everything I wrote ended in an exclamation mark?!)

After edge finishing the two hinge reinforcement plates, I shot them with primer.

Primed!

Then, my attention turned back to the tab.  I’ve clecoed the elevator half of the tab hinge back in, and on the right you can see my drilled riblet!

Drilled riblet! (Okay, I've had enough of the exclamation points.....!)

Here’s a better picture. I basically drew a line perpendicular to the hinge line up from one of the holes along the trim spar, then spaced them at 1.5 and 3 inches. That spaced everything evenly, and gave me plenty of edge distance all around.

Don't look at my edges, they aren't finished yet, but you get the idea.

Then, I stuck the tab on and inserted the hinge.

As some would say, "Easy Peasy."

Other direction, just for kicks (not as much deflection due to cleco interference, but again, you get the idea).

Because I bought a longer section of hinge to replace my bad first attempt, my hinge pin was long enough to actually fit (Van’s says they will send you the real one (because it needs to be longer than 18″) in the finish kit.

I got to bending.

After more bending, I ended up with something like this.

Ooh, isn't that pretty! The safety wire hole I drilled earlier is in the middle there, and will allow me to safety wire this hinge pin to the spar so it won't COME OUT IN FLIGHT!

Then, I figured out how to do video. They speak for themselves, but keep in mind that while my gap is intentionally small, I still need to edge finish, which will open them up.

Another video, this time a little closer. You can see I am pushing and pulling left and right to make sure there is no interference even with the small amount of play in the hinge. I think I am okay, but this will probably open up a little after edge-finishing.

Two hours of late-night-hinge-pin-bending bliss.

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Drilled E-701 (Left Elevator Skin) to Skeleton

June 17, 2010

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Wow, it’s been a week since I’ve worked on the airplane.

I have an excuse, though. I’ve been installing wood floors. Here’s the living room, almost done.

Anyway, if you remember from the last post, I had the left elevator skin clecoed to the skeleton. I went ahead and match-drilled the skin to the skeleton. Instead of using my cordless drill (because it’s quieter), I broke out the air drill and went to town. I love the way that thing sounds.

Forgot to charge the camera battery, so it charged while I drilled.

After matchdrilling both sides, this picture is me in the middle of removing all of the clecos.

Then, because I felt like I would be short-changing you if I didn’t have two pictures for you, here’s another one.

After disassembly.

Here’s the catch, though. I have a lot of thinking and pondering to do about some things.

First of all, I am planning on cutting off the elevator tab (and elevator) bent ears and just making a rib out of them. Jason Beaver did it pretty successfully here and here, so I’m basically going to copy him.

The question is whether to prep and rivet the left elevator now, the cut off the “ears” after riveting, then try to fabricate a rib, matchdrill, dimple, prep again, etc., or should I re-cleco everything together and do all of that fabrication now.

Many people use blind rivets for the extra tab fabrication, but I think I am going to try to use solid rivets. I have had some success in the past with solid rivets in tight spaces using a special bucking bar (namely, the end of a BFS (“big-freakin-screwdriver”). The question will be about dimpling.

Also, I can probably cut the ears off, but leave a little extra material. I need to make sure I line up the cuts on the elevator and tab to minimize the gab between the two, and I don’t want to cut to much off of either side. Maybe I’ll mock them up, cut one side to where I think it should be, and make sure the other side can be cut more precisely to match the first cut.

Also, many people use blind rivets for the four trim spar rivets on both sides (per the plans), but I think I can assemble in an order that allows me to use solid rivets, especially since I’m going to cut the elevator bent tab ears off; I should be able to reach in there with a bucking bar.

See how much thinking I have to do?

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