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David Paule 12-10-2015 07:28 PM

Lately all I've been doing was deburring and dimpling. Nothing much changes appearance and so I haven't bothered with photos. These include the flaps and the flap and aileron rear spar to skin braces or fairings.

I'm not including the bottom skins yet because they'll need to be stored for a while longer and it's easier to store them undimpled.

One thing worth mentioning on the W-724 aileron braces (see post 199) is that the prepunched holes (how nice that is!) are a bit larger than #40, so I had to drill them to #30 for -4 rivets. No problem but slightly disconcerting. Edit - they measure .125.


David Paule 12-11-2015 07:55 PM

The RV-3B flap inboard rib is considerably different from many of the other RVs. Here's the RV-7 inboard rib assembly, for example, using aluminum parts:

Here's a photo of the RV-3B version. It's a formed welded part that Van's supplies. I needed to tweak it a bit to make it fit and this is the way it'll fit into the inboard rib:

The angle shown in the next couple of photos was used to hold the aft edge of the top skin flat while I riveted the aileron fairing to it. I placed the rivets in, taped them in place, and then clamped the angle on. The angle itself was against the factory heads of the rivets and when I squeezed them, I squeezed right through the angle.

This worked quite well. Thanks to David Howe for the idea.


pekuba1610 12-16-2015 03:08 PM

MSP-42 for the main ribs
I have a question regarding an older one of your posts #137
Studying the plans, I wondered why to use MSP-42 at rib station 83 11/16 at all. Is there a special reason that you used the MSP-42 pop rivets for the other main ribs?


David Paule 12-16-2015 03:41 PM

Peter, that rib includes the nose rib and since it's the center rib of the five outboard leading edge ribs, it's a bit difficult to get to. I asked Sterling about that at Van's and he suggested LP4s for these and that's what I wound up using on the web to rib flange joints.

For me, it was simply a question of convenience and a certainty of getting a good set on them. Building this airplane has been an exercise in production risk reduction, not that I'm very good at it yet.


David Paule 12-16-2015 06:36 PM

No new photos, sorry, I've been doing small things -
  • Riveted the flap brace to the rear spar, both wings.
  • Inserted the plastic bushings to the ribs for wires and stuff. I'm not planning on using conduit to same some weight.
  • Deburred and dimpled the flap skins and related parts (still need to countersink some parts).
  • Made some labels for the bins for some hardware that just came in,
  • Measured the aileron pushrod length for the right wing,
  • Added the bolts between the spar web and the Z-brackets.
All necessary stuff and none of it particular photogenic.

I glanced through my cost spreadsheet and thought that you might be interested in the categories that I use to track my costs.

My major categories are:
  • Airframe,
  • Firewall forward,
  • Systems,
  • Hardware (I seem to use some after-market hardware from time to time like the light-weight MS21042 nuts),
  • Jigs and tooling (but not tools, that is, not things like drills - just specialized RV-3B stuff like the blue frame that holds the wings),
  • Tools (here's where the extra drills go),
  • Infrastructure, things like tape or lights,
  • Replacement parts, which is pretty embarrassing that I have to have a category just for that.
This is cool - I've learned how to use lists.


David Paule 12-20-2015 07:30 PM

Countersinking Flap Spars and Flap Braces
Both the flap spars and the flap braces are countersunk for the skin's dimples where the piano hinges go. Since the single-flute countersinks aren't currently available, I needed to learn how to use the standard three-flute type. First I determined that no combination of speed or pressure would reliably provide smooth countersinks using this piece of scrap.

Since the holes all appeared slightly larger than I'd drilled, I made a back-up piece. I used a length of scrap 3/16" aluminum, probably from the stabilizer's spar cut-off.

That worked. I made several successful countersinks in another bit of scrap. Once I was satisfied, I went to the airplane. This shows the back-up bar in place.

I used my slow-turning cordless drill for this.

Finally, I sprayed s dash of zinc chromate primer into the cap of the rattle can and used a Q-tip to apply it.

Wasn't hard at all once I knew how.


David Paule 12-22-2015 08:34 PM

Milestone - Control Surfaces Done
Finished riveting the flaps today. This marks the completion of the control surfaces. Like most of the RVs, there's eight of them, counting the trim tab. The shop attic will contain another five, more or less.

Here are the flaps, all riveted up.

When I said that the control surfaces were done, I meant that somewhat loosely. It's a homebuilt airplane, after all, and you know what that means. I'll probably tweak the trailing edges a bit, trim the inboard ends of the flaps (after I have a fuselage) and do a few similar things like fiberglassing the tips on the tail surfaces.

In the picture, you can see that one flap is held in the vee-jig. That jig has proved enormously useful and I believe I'm done with it, at least for now. At last I can have my work bench back.


David Paule 01-04-2016 08:33 PM

With the flaps and ailerons done, I wrapped them in bubblepack and put them in the shop rafters. I think I should have adjusted the aileron pushrods before I did that, and I might pull the ailerons down and do just that. In the photo, we're looking almost straight up. The tan stuff is the sprayed-in foam and you can see one of the four electric radiant heaters, too.

You can see the tip of a scrap horizontal stabilizer and a few other scrap parts poking out from the Shelf of Shame in the rafters.

I'm still taking care of a bunch of small things before closing the wings. Here I'm measuring out some wire for the nav/strobe lights. This is for one wing.

I'm using plastic bushings in the ribs rather than conduit. I've learned that it's not a bad idea to be generous with the size of the bushings. With cable lacing (and probably with tie wrap too) it gets difficult to move a bundle past bushings if they aren't reasonably large. Guess how I learned that.


David Paule 01-09-2016 08:40 PM

Tooling and Wires
After stringing wires through the wing, with the roll autopilot servo and the nav/strobe wires shown below,

it seemed like a good time to make a fixture to locate the rear spar carrythrough in the fuselage. But before that, see those nut plates on the ribs on either side of the servo? They were for Adel clamps for the servo wires. The way I finally located them are simpler. Also, I'm not using the strobe sync wire. While that gives a prettier flash, I'm unconvinced that it materially aids in visibility, and omitting it means that I don't have to run it across the fuselage. This is simpler. As you know, simpler is gooder.

Back to the rear spar carrythrough fixture, if course, I had to figure out where the fuselage carrythrough fit inside the spar fitting. The carrythrough is 3/16 thick. The fork for the RV-3B is in the wing root, and the assembly includes a 3/16 spacer and the .040 rear spar. This means that there's .040 clearance when the carrythrough fits. I built this shim assembly out of some .063, some .125 and some .020, giving me about .020 clearance or a little less. I double-flush riveted the pieces together and clamped them in the rear spar so that it was clamped to the aft face of the spar fork.

Here's the shim in the fork and the fixture in place. The top piece of the shim is just there to match the fork's thickness; I clamped an angle to the fork and the shim to the angle. The angle was removed for the photo.

Then when I located the aft angle on the fixture, it was a simple thing to clamp it to the shim and drill and cleco it to the fixture.

When I'm building the fuselage and I need to mount the carrythrough, I'll clamp its forward face to the fixture and it'll be pretty much centered in where the spar fork will be when I hang the wings.

Still have to make the one for the other side.

Thanks to David Howe, who sent me a couple photos of his similar fixture.


David Paule 01-10-2016 01:22 PM

Should have mentioned in the last post that I'm using hardware store aluminum angle for these fixtures. The main reason, besides availability, is that I've found that aircraft angles are sometimes not 90 degrees. The ones I have around the shop seem to be slightly more acute than that. It's pretty annoying.

The hardware store stuff is 90 degrees.

For these fixtures, strength and weight are not issues.


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