Finished Trim Tab

August 20, 2010

Prev | Next

Well, I snuck home over lunch today to make some loud noises (rivet gun) and I got the trim tab pretty much finished. I have one or two more “hard to reach” rivets to set, but for now, I’m going to call it done and focus my attention on the floors and the wings.

The tabs bottom rivets.

Here's the bottom of the tab.

Then, making sure to include the hinge (other builders have forgotten when the time comes to rivet), I got the top of the tab completed.

I do love those gold spars in the background.

Okay, so I’m a dork, and I had to get the hinge pin out and get the thing assembled.

Tab in trail...

Up tab (down elevator trim).

Down tab (up elevator trim). I still have some interference here from the shop heads of the bottom elevator rivets, but I'm going to wait until I'm rigging to sort this out any further.

A quick hour over lunch. 34 rivets set, 2 drilled out.

Prev | Next


Left Elevator Skin Riveting

July 23, 2010

Prev | Next

I wasn’t very good with the pictures today, but I did get a significant amount of work done today. I basically did a lot of skin riveting, and all went well, with a few exceptions.

First up, try to use solid rivets on the outboard part of the trim spar where they instructions say you can use blind rivets.

"Blind rivets? We don't need no stinking blind rivets."

The top row (actually the bottom of the elevator) turned out well.

These aren't the prettiest or most perfect shop heads, but they are within spec, and will do the job.

Then, I flipped the elevator over and did the top (which was harder, but actually turned out better than the bottom). I forgot to take pictures though.

I moved on to the counterbalance skin and set have the rivets, then removed the clecos and set the other half.

Here's every other one set.

Wait a minute! I’m going to need that trim tab hinge (forward half) primed so I can rivet it on the elevator.

Up on the priming table for some self-etching primer.

Moving on to the rest of the skin, here are half of the rivets set in the leading edge and inboard edge.

Halfway done with one side.

Then I removed the clecoes and finished up the first side (except for the trim tab area).

After the hinge dried, I clecoed that in place and got to it.

Clecoed in place...

Half the rivets set, clecoes removed...

All done, with the tab half of the hinge installed to make sure I don't have any binding.

Then, I flipped that bad boy over and finished the other side.


Wow, big day today. 172 rivets, four of them drilled out. (Notice how I just glossed over the riveting of my trim riblet? That’s because it was about an hour of my two hours outside. What a pain in my aft.)

Prev | Next

Started Prepping Left Elevator Skeleton

July 2, 2010

Prev | Next

Even though it was my day off, I spent the day trying not to get stung by bees (mowing the forest behind my fence) and meeting the girlfriend for food. After that, I managed to waste an hour or so installing a fan in the garage. Recently, it’s been brutal in the garage, so this morning, while I was walking around Lowe’s, I saw a small ceiling fan for $17. I couldn’t say no. It was harder to install than our nicer fans inside (no little quick-disconnect fan blades or anything), but in the end, it makes me cooler in the garage (double meaning intended).


Okay, back to work. I think you guys might have seen this picture yesterday, but here it is again…the little riblet I made after drilling.

Looks good. I am proud of this little guy.

Then, I moved over to the spar. These four holes get countersunk because they attach E-705, but the elevator horn has to sit over the rivets but still flush against the forward face of the web.

Beautiful countersinks.

While I had the countersink cage set up, I pulled the trim tab spar out of the elevator and started on it.

Countersink the top flange, dimple the bottom flange.

Aren't these countersinks nice?

After countersinking, both the tab spar and the left elevator main spar were scuffed (more), edge-finished, and then got a trip inside to the sink for a quick rinse before coming back outside to eventually get a coat of primer.

I'm getting close to riveting something, watch out!

Anyway, two very productive hours, and I think I can rivet some reinforcement plates tomorrow if I want. Wuhoo!

Prev | Next

Left Elevator Riblet, Day 1

June 28, 2010

Prev | Next

After the huge success last night, I was ready to move back to the elevator so I could get to prepping and riveting. First thing tonight was to take some small measurements, then transfer some lines to a piece of cardstock to create a template for the riblet I need to create. (Notice the title of the post is …Day 1. There will be multiple days of this dance, unfortunately.)

Here’s my first try at a template, and then the adjusted second try before being cut out.

I don't know why my first try was so big. Must have measured wrong.

Here’s a shot of the space I am trying to fill. It’s not edge finished here, but will be after I get a riblet created.

Left elevator's trim tab cutout.

Ginger was being bad inside, so she was banished to the garage (“go annoy your father”). Ha, little did we know that there was sawdust that she could be rubbing her face in. Serves us right for trying to punish her.

She's not cute at all.

So this is actually my second aluminum riblet after bending one of the flanges up in a vice. I think that edge is too sharp.

It's looking good so far.

But, even though I was really careful to finish all the edges before bending (like I forgot to do on the first one), I still got a crack.

I put a picture of my crack on the internet. Ha.

Even with the crack, I thought I would show you what I intended before scrapping the piece and starting over.

This is the general idea.

But then I got frustrated and just cut the forward part of the riblet off, and put it in place to see what it would look like.

Hmm. This doesn't look horrible, but I'd rather have the forward part of the rib, and the tie-in to the spar.

So, after an hour outside, I have to scrap the part and start over. Boo.

(To be honest, this is the really fun part of building. I get to use my thinking cap.)
Prev | Next

More Trim Tab Hinge Drilling

June 27, 2010

Prev | Next

After a motivating afternoon actually getting to sit in an RV-7, I got back to work on the trim tab. Here, you can see my new 3-foot-long MS20257-3 next to the old (and not perfectly aligned) 18-inch MS20257-2 from Van’s. It’s a little wider to give me some more edge distance.

New on top, old on bottom.

First thing, I got the new piece cut to length. It ended up being a little shorter than 18 inches… I made sure the elevator side had a hinge “ear” on each end.

I eye-balled the hinge pin length a little long. Van's tells you the hinge pin they ship with this kit is not long enough to bend and safety to the elevator, and that they'll ship the real one in the fuse kit (or finish kit, can't remember). I guessed it was about 2 extra inches I needed for the bends and then cut the hinge pin.

Then, I spent a good amount of time Just getting everything lined up. I am a little frustrated at this point, because the supposedly straight line of holes on the elevator is not parallel to the supposedly straight line of holes on the tab. This means that with the trailing and inboard edges of the tab aligned with the elevator, the gap between the leading edge of the tab and the elevator cutout is smaller near the root than the tip of the tab.

Inboard and trailing edges aligned perfectly.

Here's my inboard edge.

So, again, I strayed from the directions. I held the hinge in position, making sure the actual pin was directly in the middle of the gap as shown in the picture above at the root (smaller gap) edge and at the outboard (larger gap) edge. I figured as long as the pin was directly centered, I’d be okay. Then, I clamped it in place, and marked a single hole (see below) for drilling. I couldn’t pick the edge hole, because it was covered by my square.

On the drill press, ready to drill a single hole.

I repeated this for another single hole on the tab side, again, making sure the hinge pin was perfectly centered between the two surfaces.

Two holes drilled and clecoed.

At this point, it was close to being locked in place. I did notice that these hinges are somewhat flexible, so while I marked every hole for drilling, I really only drilled a few more before clecoing it in place and match-drilling the rest of the holes.

(A more technical side note…because I upped the hinge size to a MS20257-3, the hinge was too wide to fit inside the radius of the elevator and trim tab spars. When matchrilling, I had to change the order of the skin, hinge, spar to accommodate the extra length, then I went back and ripped a small (1/16″) strip off of the hinges so they would fit nicely in the radii of the spars.)

Here are my feet, ready to keep going on the hinge.

Fast forward after some drilling noises, and here are the two halves, each clecoed to their surfaces.

Ooh, looks good.

I still have a little bit to trim on the elevator skin, but I trimmed enough to allow some motion today.

You can just see the rounded (so it slides in easier) tip of the pin in this picture.

Here’s a closeup of how much extra pin I think I need to make the bend forward (along the spar flange) and then down (along the spar web) to a small safety-wire hole I have yet to drill to safety the pin in place.

Man, that thing is long. (TWSS)

After getting the pin in, I took out every other cleco on each surface so I could move it back and forth.


Tab up (or elevator down trim).


Tab down (or elevator up trim).

After dancing around for a little due to how great the tab looks on the elevator (and how well-aligned it is), I took the thing apart, ripped the 1/16″ off of each hinge half, and fired up the scotchbrite wheel to clean up all of the edges.

Look on the lower right part of the tab. That little angled cutout is so the hinge hides nicely under the tab skin.

I figured now would be a good time to finish match-drilling the tab. Let’s go find E-718 and E-717.

There they are!

Apparently I thought it would be a good idea to show you my scotchbrite wheel. That little groove is just getting to the right size so I can run the edge of a piece of aluminum down it and it perfectly rounds both sides.

I love this thing.

Back to the tab horn. The directions would have you use the clevis pin (don’t have this yet because I haven’t ordered the tab motor) to line up the two horns. How about two perfectly-fitting #30 clecos?

For balance purposes, I put one on each side.

Three of the holes are pre-punched, and two are not.

Just before match-drilling everything.

All done.

All done. (From another angle.)

I was planning on at least polishing the tab for now, so I marked off where the horn sits. I’ll prep and prime this little area under the horns, but I’ll leave the rest polished. (The bottom of the tab is going to be a good place to teach myself how to polish aluminum.)

The horn location, marked for future priming.

Whew. That was a good two hour work session today. It was like a sauna (more like a steam bath…this is the south!) in the garage today. I kept sweating on the airplane. (People say they put blood, sweat, and tears into their projects. I’ve got one covered, and will undoubtedly bleed and cry because of the project sometime in the future. Have to have something to look forward to, right?)

Prev | Next


June 22, 2010

Prev | Next

After getting stung by a wasp two times in the last two days trying to mow the lawn in the backyard, I gave up (shows determination and perseverance, huh?) and retreated to the comfort of my garage for some airplane work (the floors can wait until tomorrow).

Back to the tab. Before I do any more cutting on the elevator, I want to get the tab hinge drilled so I know exactly where the outboard edge of the tab will swing. I am doing this before they really tell you to in the directions (the directions have you actually finish the elevator, then start working on the tab.

Anyway, you are supposed to draw a line 1/4″ from the loop edge of the tab, and first matchdrill that to the tab. (I started with the elevator side, which eventually bit me in the ass. Read on.)

I decided to mark both sides with the 1/4" line. Hmm. Doesn't look like there is going to be a lot of edge distance.

Then, I took the hinge apart (you can see the hinge pin in the next photo) and clamped the elevator side to the elevator, lining up my 1/4″ line in the first prepunched hole, and aligning the first hinge loop where I thought it looked good (making sure this fit with the plans).

Hint: If you take apart the hinge, you can easily clamp the hinge half to the elevator (and tab, with the other half).

Next, I lined up the outboard side. This tab hinge is nice and square with the edge, and with the holes.

Let’s drill!

Here are 6 holes drilled (I'm working inboard to outboard).

All done with the elevator side.

Next, I reassembled the hinge and spent a few minutes just kind of getting everything lined up.

I wish this were the final product, but this is just me mocking things up before drilling.

With the greatest of coordination, I managed to hold a straight-edge against the inboard edge, line up the inboard pre-punched hole with the 1/4″ line, and line up the trailing edge of the tab with the trailing edge of the elevator, AND take this picture. Boo-ya.

Looks good so far.

Then, I drilled the inboard hole. The inboard side is perfect. (Can you tell that some other part may not be by the way I phrased that?)

If you look closely (lower left corner), you can see that the tab trailing edge is further aft than the elevator trailing edge.

I was pissed. I lined up the hinge with the elevator edges and holes, and with the tab edges and holes. This means that either the elevator or the tab isn’t perfectly square.

I thought about just moving the tab forward, but then there would be slightly different distances between the skins from inboard to outboard. I measured it…it would have been about 1/32 difference. No one would have noticed except for me.

But…I can’t leave it alone. I’m going to reorder the hinge and try again. This time, I’m still not going to follow the directions. If you make the hinge perfectly square to the tab, it’s going to be off on the elevator side. I’m going to have to split the difference between both by first clamping the tab in perfect position, then clamping the hinge in place and matchdrilling a few holes.

Admittedly, I should have followed the directions by starting with the tab edge, but it wouldn’t have mattered, it still wouldn’t have been a perfectly square hinge line after I was done.

The tab hinge is AN257-P2 according to the materials list in Section 4, but the part shows MS20257-2.

I also think, given my edge distance worries (must be okay because it is per the plans? I don’t know), I am going to order the MS20257-3 (or AN257-P3, which is 1 + 1/4″ wide instead of 1 + 1/16″). I checked with Van’s, and they want $9.70 (plus $4 handling, plus $12 shipping or something) for an 24″ piece of AN257-P3.

I checked aircraft spruce, and they wanted $4.75 for a 3′ piece and $1.73 shipping via USPS.

Which one do I choose?

Duh. $6.48 for my first re-ordered part. Bummer. (It’s better than a $60 elevator skin, though!)

Here are my edge distances.

I love this kind of building. Thinking, playing, mocking up, etc. The normal matdrilling dance gets old…this is the stuff I really like.

1.0 hour tonight. Frustrating, but fun.

Prev | Next

Bent Left Elevator Trailing Edge

June 2, 2010

Prev | Next

Sick again today, but I did get a little work done.

First, I spent a considerable amount of time looking at the 4 horizonal holes below. The plans show them as blind rivets, but there has to be a way to get solid rivets in there.

After much deliberation, I think if I drill them to #40 now (gasp, without matchrilling!?) Then I can deburr, scuff, and dimple the area now. I’ll do the same to the equivalent holes in the trim spar, and then attach (at a minimum) the top skin to trim spar holes with solid rivets. I think I will be able to get both sides, as I am planning on cutting off the “bent tabs” from both the elevator and trim tab.

First, drill to #40.

Then, deburr interior and exterior, and scuff the interior only.

I got the c-frame out again and dimpled the holes.

I should be able to make that work out for me, but more on the bent tab cutting later on.

Next up is bending the trailing edge. After inserting and taping a 1/8" dowel in the trailing edge, I bent it in my bending brake. This picture is about halfway bent.

Then, I removed the dowel, bent it the rest of the way, and did the same with the trim tab since I was in the bending mood. (Side note, the trailing edge on the elevator looked great, but was not constant radius…it was larger radius toward the tip. I grabbed the hand seamers and gently squeezed the areas so they were all the nice crisp radius that the inboard trailing edge was.)

Trim tab bent.

Also, I way overbent the trim tab. There are no stiffeners in there to stop you, so you can basically flatten the thing, even with the dowel rod in there. I opened it back up a little by hand, but it’s not perfect. If I can’t get it back to perfect, I’m going to order another one. I think I can work with this one, though.

This is a radius shot of both the elevator only.

Here's one with the tab held in place. Looks good to me.

Another sickly hour today. Can’t complain.

Prev | Next