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David Paule 02-10-2014 08:45 PM

More Tank Stiffeners
I made a second set, this time for the right tank. I've also deburred the right-hand tank ribs and baffle and made those little flapper valves that are shown on drawing 12A for the inverted system.

While my carbureted airplane won't have an inverted system, some RV owners have reported that the flapper valve helps when low on fuel in turbulence, so I added them. Also, it should be useful during slips. I'm putting them into both tanks.

Both tank skins are now drilled for the caps and the drains, too.


David Paule 02-12-2014 12:32 PM

Flapper Valve
Thought that perhaps someone might like to see the flapper valve. This in the one for the right tank.

The plans says to install it for the inverted fuel system, which I won't be installing. But this should be helpful in slips and turbulence.

Here's what the plans shows:


But the plans didn't include the tooling hole or the stiffening features embedded into the rib. That led me to making the hinge shape as I did. If I'd made the flap taller and moved the hinge higher, things would have been a lot easier, but I didn't think of that when I was doing it.

I also wanted to keep a bit clear of the bottom edge, and to avoid Pro-Sealing the valve, I'll tape it open when I seal the ribs to the skin. The valve is rounded simply because square corners contributed nothing except an attraction to the planer Earth. This is ever-so slightly lighter.

The final detail was how on earth could I prevent the pin from coming out? Turns out to be a no-brainer: with the bend end aft, the baffle will retain it. Of course the forward end needed to be long enough so it doesn't fall out then.

Worth mentioning is a tiny bit of philosophy.... One reason I'm making small weight-savings changes like this is just to keep in the habit of doing it. Perhaps if I do it often enough I'll have a light RV-3B.


David Paule 03-02-2014 08:25 PM

Oops And Go
Good news and some bad this time. The bad news first.

I scrapped the tanks just before sealing them. I made a mistake, the Mother Ship said it would be a relatively easy fix, I didn't care for the way the result turned out and decided to make new ones. Parts on order.


Moving on.

Figured that this would be a good time to rivet up the outboard leading edge, but before I did that, I needed to work out the installation of the landing light and the stall warning vane in the left wing. You're probably thinking, "What do you mean, work it out? Get the Duckworks landing light mount like the rest of us, and install the Van's stall warning vane."

Well, this is an RV-3B and it's not entirely that simple. The Duckworks lens is a nice fit - thanks, Duckworks! - but the mounting plate is not. I figured out an alternative mounting approach. And the stall warning vane assembly is pretty nice. It even includes some pre-punched parts! But it's intended for the RV-7, -8 or -9 so some of the parts won't fit. And it needs an inspection hatch.

I saw a very nice RV-8A at the 2013 LOE fly-in that had the vane just inboard of the landing light lens. The pilot said it worked well and access was through the lens. It looked as if I could adapt that to this installation. I had to make a couple other tweaks, though, for ease of future access.

Here's the stall warning assembly and mount combined with the landing light mount support. Please note that this assembly was made without the fasteners getting tightened. I just assembled it to check the fitting up of the thing. I didn't tighten the fasteners because the tools were outside and it was cold today. I promise I will before it's permanent.

And another view,

The landing light mount itself is partly supported by this piece, but it's another assembly, this one composite. I was glad for that since I LIKE working with composites. Here's a bit of fiberglass I made for the mount.

Pretty easy.

Back to the outboard leading edge, I'm gluing the carpet strips to the cradle pieces now.


David Paule 04-11-2014 10:13 AM

Stall Warner Installation
After needing to be out of town for a few weeks and then another short trip, I'm slowly getting back to it.

Right now I'm trying to find the place to cut the slot for the stall warning vane. This isn't part of the RV-3B kit, but I bought one from Van's. It's going into the outboard-most bay on the left leading edge, and with the leading edge now riveted but not attached to the spar, this is time to cut the slot.

I made a short straight strip of .032 aluminum to simulate a vane, so that I could move it in and out until it touches the leading edge. I still need to see if the bend in the vane (not shown) is inside the wing, right at the leading edge or ahead of the leading edge.

The keen observer might recognize that I made this one a mirror image of the way the stall warning kit is designed. This will permit access from the tip or from the as-yet-uncut landing light lens hole.

RV-3B: Not like the other kits.


ppilotmike 04-11-2014 04:47 PM

Nice Work!
I still want to see your landing light install. I haven't done mine yet. Still in head-scratchin' mode. ;)

David Paule 04-15-2014 08:56 PM

Landing Light Mount
Here's the landing light mount. It's made of some unidirectional carbon fiber kite spars that I bought from, which has a local store. I had to make the fiberglass tabs myself.

The blue tape is to identify the outboard end as the mount isn't symmetric.

The mount with the light installed is easily removable through one of the lightening holes in the nose rib at the tip. Or the light itself could be removed through the lens in the leading edge if I didn't feel like removing the wingtip.

The mount itself weighs 33 grams. It replaces a Duckworks landing light mount which weighs 142 grams as-is, or 137 grams with the mounting cut-out cut.

The Duckworks mount didn't actually fit all that well and replacing it saved me 104 grams or 3 2/3 ounces. Plus it was cheaper. Of course now I've got a couple Duckworks mounts for sale.


ppilotmike 04-16-2014 10:16 AM

Kite Spars

So how will you mount the kite spar ends to the rib webs inside?

David Paule 04-16-2014 10:39 AM

The ends of the carbon rods will fit in bushings in the large holes in the outboard rib and in this rib.

I've got to do some cutting in there for the landing light lens and the stall warner vane before I mount the light.

Since carbon and aluminum can corrode, the bushings isolate the two.


ppilotmike 04-16-2014 01:30 PM

Will the rods free-float in these bushings then? What keeps them from sliding around?

David Paule 04-16-2014 05:22 PM

There will be retainers that I haven't added yet.


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