Right Rear Spar Doubler and Reinforcement Fork

September 8, 2010

Prev | Next

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.

Prev | Next

Advertisements

Finished Countersinking Right Spar Flanges

August 24, 2010

Prev | Next

Well, tonight wasn’t a long night in the shop, but it was a good night.

First of all, there was a package sitting on my doorstep when I got home from work. After the excitement for my new Cleveland Main Squeeze died down as I realized the package wasn’t from Cleveland Tools, it quickly came back when I realized it was the missing W-712-R ribs that I had been shorted (what a cruel world!) in my wing kit.

Who knew I could get so excited about wing ribs.

Drumroll please!

{Triumphant music}

Okay, Andrew. Time to settle down.

Let’s finish up this right spar flange countersinking.

From the first issue of the 2005 RVator (thanks to Brad Oliver, for the link) and to A VAF Post (again, thanks Brad), I was able to make this cute little HTML table for you.

From the first 2005 issue of the RVator (page 10):

We countersink until the top of the screw is level with the surface, then go 2 clicks deeper on the microstop. The actual outside diameter of the countersink measures .365″ to .375″.

Countersink Widths for Numbered Screws
Screw Size Width [in]
#6 <0.3125
#8 0.365-0.375

So, I broke out my trusty digital calipers, zeroed them out, and dialed in .370″ (right in the middle of 0.365″ and 0.375″).

Just for kicks, I thought I would show you how much bigger that is than a #8 screw. The larger size allows the dimpled skin to nest nicely in the countersink.

WHOSE TOES ARE THOSE!?

SOMEBODY’S TOES KEEP GETTING IN MY PICTURES!

Anyway, I proceeded with countersinking the tank skin attach holes only (the access plate attach holes are smaller.) I am following the directions here exactly, using a #30 piloted countersink (which nestles nicely in the #8 nutplate) as my guide.

I stopped and verified the countersink depth every few holes. Looking good!

About halfway done with the bottom flange.

Here’s a countersink for your viewing pleasure.

The rivet on the right doesn't look flush, but it is. I promise.

Finally, I finished with the bottom flange. (Notice the three sets of four countersinks on the right side of the picture. Those are for the access plates. They use a #40 piloted countersink and are countersunk to a width of 0.312″ (which is less than 0.3125″)).

Ta da!

Oh yeah, now I have to do the other side.

With a noticeable lack of in-process pictures, I finished the top flange also.

Ta da! (Déjà vu?)

1.0 Countersinking-filled hour tonight.

And, I’ve finished the first three paragraphs of the wing section of the manual. Score!

Prev | Next