trim spar | Andrew's RV-7 Build Log

Left Elevator Riblet, Day 2

June 29, 2010

Captain’s Log: Day 2. Great success with the riblet.

So after yesterday’s wasted (I know, it wasn’t really wasted) time making two FAILURES of riblets for the elevator trim cutout, today’s worked out much better.

I had actually woken up at 3am in a cold sweat; “Oh my gosh, I need to tie the front of the riblet into the elevator trim spar.” (Warning: Cold sweat may be exaggerated.)

Anyway, I got out the jigsaw with a fine metal-cutting blade and found that this technique was far superior to the snips, which leave little ridges along the cut.

So, more measuring, tracing, and drilling/cutting.

This is try #3.

Then, after judiciously edge finishing (which is a must before bending aluminum…ask me how I know.)

Okay, Those bends are pretty good, let's work on the front.

Hey pups! (I took about 15 pictures of them for your viewing pleasure, but this is the only one that wasn't too blurry.) Jack and Ginger, curious about the airplane.

Also, I had picked this surface conditioning kit up at Harbor Freight. 1-inch diameter, and blue is finer (I think) than maroon.

This worked pretty well for quick finishing. I want to try the larger sizes, too.

You can see from the paper template on the right that wasn’t going to tie in to the spar. I cut out the corners on the piece to the left pretty roughly.

Old template on the right, current work piece on the left.

So then I edge-finished and bent the three tabs that tie in to the spar. Because there was a dimple already in the bottom flange of the spar, I went ahead and drilled and dimpled that one ear on my new riblet.

How do you like the nice sharp picture of my set of needle files and permagrit block? (And very blurry pic of my riblet being dimpled. The yoke and die just barely fit.)

Here’s the almost finished product.

It's kind of cute.

So it doesn’t fit “perfectly” in the openeing, but this is close enough that I don’t need to remake it. I’ll tweak it a little and reduce some of those gaps you see in the coming days.

Pretty darn good.

The big gap on the left is actually the elevator skin bowing locally that I need to fix. The riblet is actually straight.

I'm so happy this one worked out.

Maybe later this week or this weekend, I’ll get this tweaked and drilled/dimpled. Then, I can move ahead with prepping the elevator for prime and riveting.

An hour of wuhoo!

Prev | Next

Leave a Comment » | Empennage | Tagged: dimple, edge finishing, elevator trim, Ginger, Harbor Freight, Jack, jigsaw, Permagrit, riblet, trim spar | Permalink
Posted by Andrew

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

Leave a Comment » | Empennage | Tagged: bending brake, bent tabs, Blind Rivets, C-frame, Deburr, dimple, dowel, Elevator, scuff, solid rivets, Stiffeners, Trailing Edge, trim spar, trim tab | Permalink
Posted by Andrew

Primed Some Left Elevator Stiffeners

May 29, 2010

Prev | Next

Not too much today. I got the lower left elevator stiffeners deburred, dimpled and primed.

Here are some of the stiffeners on the priming table.

Then, I turned my attention back to the skin to start devinyling.

Left elevator, ready to be devinyled.

Here are a couple lines showing my devinlying process. These are made with a soldering gun held against a wooden straight-edge.

Oh yeah, almost forgot. I stumbled across another Harbor Freight coupon. I bought this ~$10 storage container for wing hardware.

I have two already, one for rivets, and one for Empennage hardware. I assume I'll need a third for wing hardware (I'll combine the rivets from wing and emp if need be).

Okay, back to the project. I’ve pulled off some of the vinly strips.

Pulled off some of the vinyl strips.

Here, my devinyl line overlaps the tracing a little.

Another angle here.

So I put the trim spar in position, and realized I could move the line back a little, so that's what I did.

Next, I deburred and scuffed the skin in preparation for dimpling. (It’s easier to scuff before dimpling.)

The lines to the right have been scuffed, the trim spar reinforcement area has not.

A closeup of scuffed versus not-scuffed.

To scuff an area (in preparation for priming), I scuff in one 45° direction…

45° to the right.

Then, 90° from that.

All done. You can sort of see the two directions.

Finally, some dry stiffeners, ready to be backriveted to the skins.

Pretty stiffeners.

I always like to take a big picture shot at the end of the day.

Left skin, ready for dimpling.

Tomorrow, maybe a little skin dimpling, priming, and backriveting stiffeners.

One hour.

Prev | Next

Leave a Comment » | Empennage | Tagged: Backriveting, deburred, devinyling, dimpled, Harbor Freight, left elevator, primed, rivets, skin, soldering gun, Stiffeners, trim spar | Permalink
Posted by Andrew

Started Left Elevator

May 24, 2010

Prev | Next

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:

Fix a few over-driven rivets (and a couple that bent over that I didn’t catch at the time.)
Figure out how to add RTV to the trailing edges after the fact (anyone have any ideas?)
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.