More Trim Tab Work

August 17, 2010

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Well, before I can dive into the wing, I need to finish up the trim tab. All that’s left is to fabricate two riblets, get everything prepped and primed, and then rivet the tab together.

First, let’s get some riblets made up. Just like the elevator riblet, I started with some thick paper.

I used the packing list envelope from the wings, because it was literally right in front of me when I started.

I got the larger one cut out of 0.025″ aluminum sheet pretty easily, and the first try fit like a champ. I moved on to the smaller one, hoping for similar luck.Fast forward a couple minutes (many minutes!)…

Can you say "third time is a charm?"

Nope. Third one wasn’t good either.

Let's try again (fourth time). I just couldn't get the bends right.

That one worked. And of course I forgot to take a picture.

I drilled a couple holes in each riblet through the skin.

Finally, fourth time is a charm.

Wuhoo, let's get this tab finished.

But, it was getting late, and there were a couple of puppies somewhere that needed attention. (Turned out, they were asleep when I went inside, and I got growled at. Thanks, puppies.) Before I headed inside, I disassembled the tab and pulled out the wing spars to inspect.

Tab components, ready for cleaning and priming.

After looking the spars over, I found many places where the spars had been “polished” with a scotchbrite bad to work out small scratches. It seems that everyone has these, and is no cause for alarm.

On the other hand, I found some bad juju. This is a closeup of a couple dings that look like something bounced on the spar. Keep in mind, that hole is a #40 (3/32″), so these are really small.

Still, that's not good.

Whoa. What. Is. That!?

Holy frijoles, Batman! That is a huge dent in my spar flange!

Here's a closeup of the dent with a straightedge held over it.

Another angle.

I took a couple pictures of the underside of the flange. I tried to use the light to demonstrate the distortion.

That curved white streak is actually the light reflecting off of some spider cracks in the anodizing.

Here's another angle.

Not really related, I just snapped a picture of the spars laying on the table.

At least they look pretty.

1.5 hours on the trim tab today. I’ll email Van’s first thing in the morning about the spars and then post what they say.

I’m pretty disappointed though. Nothing could create that dent without making a big noise, maybe something being dropped or falling over. Which means someone probably knew it happened and didn’t say anything, or the inspection process didn’t catch it. Either way, I’m not super excited. I’m guessing it wasn’t Vans’ fault, but hopefully they will make it right.

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Left Elevator Riblet, Day 1

June 28, 2010

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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.)
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More Trim Tab Hinge Drilling

June 27, 2010

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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?)

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Bent Left Elevator Trailing Edge

June 2, 2010

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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.

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Started Left Elevator

May 24, 2010

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Well, it’s monday. And even though I have a couple things remaining on the right elevator, I am going to follow the flow of the directions and move on to the left elevator before coming back to finish both of them.

In addition to the items they want you to do to both at the same time (roll leading edges, install rod-end bearings, etc.), I’ll have to come back to do three things on the right elevator:

  1. Fix a few over-driven rivets (and a couple that bent over that I didn’t catch at the time.)
  2. Figure out how to add RTV to the trailing edges after the fact (anyone have any ideas?)
  3. Trim down the counterbalance. I elected not to do this on purpose.

Anyway, on to the left elevator. Here’s the obligatory changing-of-the-plans shot.

On to the left elevator (and trim tab).

As I only have about a half an hour tonight, my plan was to just cover the basics. First, lay out all of the left elevator parts.

It doesn't look like a lot of work...

Devinyl the skeleton parts.

This picture is almost identical to the one before it, except for the missing blue vinyl on the skeleton parts.

Then, on to real work…kind of. The manual wants me to attach the hinge reinforcing plates to the spar, then move to the outer ribs.

Here you can see the two outer ribs fluted. I haven't straightened out the rib flanges yet, will get to that soon.

Blah blah blah, assemble the skeleton. For now, I didn’t do any match-drilling. I do that hole-by-hole as I take the thing apart.

This one will be more interesting due to the trim spar.

Finally, I found one more of the stiffener angles. I got that devinyled and then cut from hole to hole to form some of the smaller stiffeners.

More small stiffeners. These go between the main spar and the trim spar (ahead of the trim tab).

With that stuff done, I headed inside and caught someone with their hands in the cookie (doggie-treat) jar.

That bottom shelf has the doggie-treats on it. (We have really patient dogs. /sarcasm off)

Lucky you, I got some video.

Anyway, a short half hour of left elevator prep.
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