Andrew's RV-7 Build Log

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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.

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