FINISHED DEVINYLING WING SKINS!

October 18, 2010


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WUHUOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!

(Not that I don’t like devinyling…)

No really, it’s kind of mindless, easy time-passing.

The real reason this is a win is that it is really the last thing (except for all of the leading edge, aileron, and flap skins) I can devinyl in the airplane room before needing to buckle down, finish up the floors, and really get started on the wings.

 

I think this is the right upper outboard skin, skeleton side.

 

 

And the other side.

 

Once I really get going on the other side, I need to catch the left main spar up to where the right is, build the left rear spar, and then do the rib prep trick. Then, I’ll build a wing stand and start the fun parts (Ha! They’re all fun parts!)

0.5 hours.


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Leading Edge/Tank Cradle, Right Tiedown Bracket

September 28, 2010

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A few days ago I had the circular saw out, and I saw (pun intended) a 16″ wide piece of 3/4″ MDF sitting around, so I took a quick look at the plans, and decided that 16″ x 16″ might be a good starting point for the leading edge/tank assembly cradle.

The plans (second picture down) show 13″ x 15″, but I’ve heard that some people break the cradle at the thinnest point.

Anyway, it took me all of 30 seconds to cut the 2 big square pieces and the four triangular pieces also pictured.

Tonight, I pulled those out for assembly (a quick night in the shop).

16" x 16" cradle walls, with 4 triangular supports.

Van's wants you to mount them on a 36" long 2x4, but I decided to go another route. Read on.

I used a thick magic marker to offest from a tank rib (room for pipe-insulation to protect the skins).

After the cut.

Tada!

After the cut. (Déjà vu)

Tada! (Déjà vu)

After both were cut out with the jigsaw, I laid (layed? Em, help me out here) the tank rib into the cutout to make sure I had offset the cuts enough.

Looks good to me.

So, here’s an expplanation of my “alternate route”.

Because Van’s specifically states that this just helps in assembly, and is not an alignment jig, I decided I didn’t really need to take up a lot of space with a 3 foot wide cradle that would undoubtedly get in the way. Instead, I am making the two halves of the cradle independently, and will use them (approximately 3 feet apart). I also figured they would be stable enough with one of these triangular pieces on each side, which they were.

I predrilled the cradle, but not the gusset, and it cracked as I assembled with some coarse-thread drywall screws. Bummer (I never thought I would put a picture of my crack on the internet.)

For the other ones, I pre-drilled the gusset, too.

After everything was all said and done, I am pretty happy with them (damn crack!).

I need to grab some pipe insulation to protect the skins.

Best part, they nest nicely for storage before (and after) use.

Then, I looked around for something I could get done with the half hour of attention and “eyelids-open” time I felt I had left.

I shot a quick coat of primer on the right tiedown bracket (and spacers), and then waited for the first sides to dry before flipping them over and hitting the other side.

While the whole thing dried, I needed something else to do, so I grabbed the  T-715 Anti-Rotation brackets (which come all connected like the old plastic models used to. Remember you had to use a pocket knife to cut off the little tabs after bending and twisting one model piece from the rest of the pieces.)

Anyway, after getting them apart, I edge finished all four on the scotchbrite wheel. Maybe 10 minutes, and for the record, I am going to log this time under Spars, because I’m waiting for the tiedown brackets to dry. I don’t feel like adding an entry under tanks just yet.

When it is years and years from now, and you ask me how my hours it took me to finish my tanks, and I say “xx hours,” remember to add 10 minutes to that to get the real answer.

Edge finished anti-rotation brackets. (How do I edge-finish the inside edges of these? Hmm.)

Okay, now that the tiedown bracket is dry, let’s find those AN426AD3-7s – HOLY CRAP THESE THINGS ARE LOOOONG!

Whoa. Long rivets.

4 of 8 rivets set (squeezed).

Tada! (That's three "tada"s today. Aren't you lucky!?) Don't forget the nutplates on the other side. I almost did.

Oh, and by the way. Don’t prime and then wait 10 minutes for things to dry, the primer really hasn’t cured, and it will scrape off with a fingernail. After waiting 24 hours, or better yet, a few days, this stuff gets rock solid. I need to remember that.

I shot another coat on these after they were riveted. I was too ashamed of the first coat to take a picture. Sorry.

8 rivets and 1 hour. 0.5 in “Wing” and 0.5 in “Spars.” (I’ll put the log in both places. We’ll see how that works.)

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Backriveted Left Elevator Stiffeners

June 1, 2010

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I wasn’t feeling well today (sore throat, could harldy swallow), but after a nice long sleep-in and a nap in the afternoon, I went out to the garage partly because I wanted to sweat out some of the demons. I didn’t take a ton of pictures, but I managed a few.

I broke out the c-frame and dimpled the skins.

First up, skin dimpling.

I did much better on the trailing edge dimples than last time (see this post).

This is the worst one, but it still looks great, and is hardly noticeable unless you are really looking for it.

After dimpling, I wiped down all of the scuffed areas with MEK to rid them of fingerprints (oils) aluminum dust, moisture, etc., and then primed.

Primed interior. Notice how I leave a lot of the blue vinyl on the skins? This helps keep weight down (although undoubtedly adds to build time while I painstakingly trace around the stiffeners with a marker and use those lines to devinyl.

Moving back to the skeleton, I mounted a one-leg 1/4″ nutplate in the forward tooling hole of the counterbalance and tip ribs. This will hold any future weight I need to balance the elevator with paint.

I used an undersized countersunk screw in the tooling hole to help locate the nutplate, then drilled one hole and clecoed from the back.

Both holes drilled, and the main hole enlarged to something a little larger than 1/4"...I can't remember...maybe 5/32"?

Next, I moved back to the spar. I have read where a few people have added a hole in the lightening hole area of the elevator control horn/spar area. The right hole is for manual trim or for the (what I’ll call “retracted”) jack screw and wiring runs for the electric trim motor. I, like others, don’t like the idea of the wires and jack screw sharing the same hole, so I drilled another hole, in which I will add a 3/8″ snap bushing.

Pilot hole eye-balled.

Crap, I didn't even get a picture of the final size hole. (I drilled it to 3/8".)

After completed the extra hole, I noticed the skin was dry. Nothing to stop me from backriveting, now.

Rivets place in, and taped to, the first stiffener row.

Same thing with the trim reinforcement area.

After backriveting the trim reinforcement. Man, this makes me happy.

The next couple rows, done.

The bottom half went smoothly. The top half now has rivets taped in place.

Where are those stiffeners?

This isn't a very exciting picture, but they are all riveted.

Here's the inside.

I love this picture. This is the trim reinforcement plate area.

So nice. (That scratch at the top is very superficial. It'll buff right out, I promise.)

Biggest lesson today was about the aft-most rivet in the stiffeners. When bending the skin out of the way to reach that rivet, everything twists out of alignment. If you start with that rivet, it is easier to make sure everything is flush than if you rivet the forward ones first. Start from the back and move forward. You will get better results.

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Right Elevator Stiffener Riveting

April 18, 2010

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A few days ago I got a little time in on the project. I’ll see if I can remember what happened. 3 hours, 116 rivets…2 of them drilled out and reset. Here we go. First thing, in preparation for stiffener riveting was to get the skin devinyled. Here’s my devinyling table, wooden stick (won’t dissapate heat) and permanent marker.

Ready to use the soldering iron to devinyl.

After devinyling the inside of the right elevator skin.

For some reason I like devinyling. Don't ask me why.

Here’s the outside of the skin after devinyling. This actually takes a long time to do.

I just devinyled the stiffener holes. I'll devinyl the rest after drilling to the skeleton.

At some point last weekend (can’t remember which day), I was sent to Home Depot (maybe Lowe’s…it was a busy day) to grab some gardening supplies. I took the opportunity to grab some indoor/outdoor carpet for the workbenches.

Here's what I call my toolbench with a new carpet surface.

You should be able to see the “workbench”‘ with carpet on it in future pictures. Anyway, I grabbed the skin and did some deburring (interior and exterior) and some scuffing (interior only, for priming).

Scuffed strip on the left, non-scuffed on the right.

After a few more minutes, I dimpled the skin (no pictures, sorry), and then decided they were ready for priming.

Where is that self-etching primer?

i got the picture order backwards, so you’ll see the skin primed later, but here I am getting ready (or just finishing) stiffener edge prep. I usually use my Permagit block to knock down any ridges, edge deburring tool (pictured below)  to chamfer both edges, and then a scotchbrite pad to smooth everything out.

Right elevator stiffeners and my edge deburring tool.

Here’s the picture of my primed skin.

It looks sloppy now, but wait until I get the vinyl off. Then the primed lines will look nice.

After the stiffener edge prep, the stiffeners got taken inside to be washed with dawn detergent.

Here are half of the stiffeners, being cleansed of their oily fingerprints and aluminum dust.

I decided to take a picture of how much detergent I use. Nothing really important, just camera-happy, I guess.

Dirty stiffeners need to be cleansed of their aluminum dust and fingerprints.

After cleaning, they go back outside for priming.

Boo-yeah, primed stiffeners.

While those were drying (and then flipped and sprayed on the other side), I placed rivets in the dimpled holes and taped them in place.

Rivets just asking to be beaten into submission.

I started to backrivet, and everything was going very smoothly.

Beautiful shop heads.

More beautiful shop heads.

God, I love backriveting.

But anyway, I got through all 116 rivets, then flipped everything over and saw these!

Ahh! Worst rivet ever!

This one is not so bad...

I figured out why this happened, and it falls squarely on me.

While I was dimpling, I didn’t pull the other half of the skin back well enough, so the skin side that was being dimpled was not sitting parallel to the faces of the dimple dies. One side of the die dented each of the last stiffener rivet holes on one side. The rivet in the second to last picture was flush against the backriveting plate, but the skin was dented, or above the backriveting plate.

I’m going to drill out all of the bad rivets on the trailing edge (of course, the worse of the bunch is on the top of the elevator, right where all of you are going to come look at my elevators), and then  try to smooth out the skin by backriveting it with a flush set from the inside out.

It might ruin the skins, which will be expensive. I’ll be sure to take some pictures of the process. Maybe it will save one of you some time and frustration…

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