scotchbrite wheel | Andrew's RV-7 Build Log

Leading Edge/Tank Cradle, Right Tiedown Bracket

September 28, 2010

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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Leave a Comment » | Wings | Tagged: cradle, Leading edge, MDF, primer, rivets, scotchbrite wheel, skins, Tada!, tank, tiedown | Permalink
Posted by Andrew

Right Rear Spar Doubler and Reinforcement Fork

September 8, 2010

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The next step on the rear spars is to trip the W-707D and W-707G Rear Spar Doubler and Reinforcement Fork to size.

These parts are shared between the RV-7 and RV-8 (and maybe more, I’m not sure), and must be trimmed if you are building the -7.

This is a tricky trim job, though, because many people have future troubles with drilling the rear spar to the fuselage and maintaining the required edge distance for the hole in THESE PIECES.

It would be best not to overtrim, and leave even less margin than what is already there.

The plans and construction manual both point to Dwg 38, which is of course not included as a full-scale sheet in the wing kit, so I got out my preview plans and started staring.

Even though I’m only working on the right side for now (will bring the left wing up to the right side’s progress when I get the replacement spar from vans), I’m going to do both sides of this now while I’m all mind-prepped to do it.

A snapshot of the applicable portion of Dwg 38. Looks like I should start measuring and marking. (No cutting yet, though!)

Keep in mind here that you measure from the edge you are about to start cutting away, so once you start cutting there is no double-checking your measurements.

Of course, I'm being dumb by doing the right side first (left is shown in the drawing above.)

Here are both lines drawn, measured, double-checked etc. It's still all making sense, so that is a good thing.

The bottom cut off. (For you OCD types, I realize I should have made the other cut first, which would have been a little less cutting overall, but oh well).

I decided to cleco the two smaller pieces together first, then transfer the lines to the bigger forks, and do those separately.

Ready to transfer the lines.

Of course, I didn’t get any in-progress shots of the fork cutting, but it went well. I then clecoed the left and right assemblies together and grabbed this shot after a few passes on the scotchbrite wheel.

At the end of this project, I am going to go back and count how many toes ended up in all the pictures. Here's...{counting}...6 more.

After some time on the scotchbrite wheel, I have two ready-to-cleco parts.

Nice and scuffed.

Then, I clecoed the doubler plate and reinforcement fork to the right rear spar and started matchdrilling.

Matchdrilling.

I had a hard time deciding if I should enlarge some of the rib attachment holes in the fork and doubler plate to final size, and I decided I would. I couldn’t find anyone who said it would be a bad idea, and now I’ll get to deburr and prime all of the rear spar components.

I did leave the majority of the rear spar “future” holes alone, though. I guess per the directions (indirectly, just in step order), I’ll drill those after priming the rear spar.

Here's a picture from the backside (actually, front side) of the spar.

Of course, I was careful to mark and enlarge to #40 the flange holes that need to be dimpled now (the reinforcement fork prevents the female side of the dimple die from getting behind these holes).

I didn't actually dimple, though. I need to leave something for tomorrow.

After taking everything apart and deburring holes, I have a few pieces ready for priming, and a rear spar with some remaining deburring before priming.

I scuffed the rear spar where I had already drilled and deburred to help remind myself what I have left to deburr.

Today’s hour was a good one; a few things ready to prime, and just one deburring and priming session away from being able to rivet the rear spar assembly together.

I need to go buy some more Napa 7220 Self-Etching Primer.

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1 Comment | Wings | Tagged: clecoed, Deburr, dimple, Drilling, edge distance, fuselage, Napa 7220 Self-Etching Primer, prime, rear spars, scotchbrite wheel, spar, TOES | Permalink
Posted by Andrew

Riveted E-615PP Trim Reinforcement Plate

April 6, 2010

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WUHOO, tool order arrived!

3 things in the order, $154.90. Ouch.

Also included was this AWESOME sticker.

Where should I put this?

Here?

On the airplane? no.

Finally, the air compressor won.

Decorated air compressor.

Look at that beautiful tungsten bucking bar.

Old and new.

Also, I got two more dimple die sets. #6 and #8, on the right.

Just for comparison. #40, #30, #6, #8. Still need a #10.

Alright, back to work. First up, using the #6 dimple dies on the E-616PP Trim Cover Plate.

Nicely dimpled. I don't think it matters that you take off the blue vinyl. Maybe that was a bad idea.

Here’s the bottom side (top side when mounted on the bottom of the elevator on the airplane).

Peeling off the blue vinyl.

Then, edge finished and scuffed for priming. I’m going to wait to prime this until I can actually by the electric trim motor since you have to drill more holes. Just thinking ahead: can I countersink and use NAS rivets for the trim motor mounting brackets? Nope. These are pretty structural (hold the motor, and therefore the trim tab, in place.) I’m sure those directions will confirm the need to dimple. I’ll need to dimple E-616PP and the brackets that are used to attach the trim motor.

Ready for priming, except for all of the extra holes I have to drill, deburr, dimple, and rivet.

Same deal on E-615PP.

Ready for priming.

On the fancy priming stand.

After shooting primer to one side of E-615PP, I decided to add 4 holes for each of my new dimple die halves.

4 holes drilled.

Tada.

7/32″ seems to work well for holes in a home-made dimple die holder stand.

7/32" is a good size hole for these.

Then, I shot primer on the other side of E-615PP. While I waited for that side to dry, I edge finished E-616PP.

Look at that nice edge. I love the scotchbrite wheel.

Now that E-615PP is dry, let’s do some riveting! I grabbed the K1100-06 nutplates (or platenuts as Van calls them) and the 14 required rivets. Remember from March 28th, I am using NAS1097 rivets here.

I am going to be using NAS1097 rivets here (smaller head than AN426 rivets) so I can countersink (instead of dimple) the holes here. That saves me from having to dimple the nutplate ears, which will save me a lot of hassle.

I finally found the rivet callouts.

I thought that because I countersank (verb tense?) the reinforcement plate that the 3.5 would be way too long, but the -3 was definitely too short. I grabbed 14 NAS1097AD3-3.5 rivets.

-3.5 (length) should work here.

I put all of the nutplates in with a single cleco and a single rivet, taped into place before starting to squeeze them. I hindsight, I should have backriveted these. So dumb.

Half of them done.

Then I did the other half.

Nice and flush. There is one that is almost proud, but doesn't affect the cover plate, so I may not try to muck it up further by drilling it out. We'll see if I can sleep tonight.

Once I got those 14 set, I grabbed the An507-6R6 screws and got the cover plate screwed on.

Ready to screw down. see in the lower left where the shadow under E-616PP is a little bigger? The dimpling kind of warped the plate. I'll have to try to coax this flat again.