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David Paule 04-17-2022 08:28 AM


Rick and Larry did the hard stuff. For me, mostly this just opens the gate to a lot more work... as you know. Kinda looking forward to it.


BoydBirchler 04-18-2022 05:19 AM

Cadmium plating ? On the engine mount? I doubt that Vans would do that on a tubular mount because of the danger's of entrapment of the plating solution in closed areas of tubing and because of hydrogen embritlement.

David Paule 04-18-2022 08:09 AM

The cad plating was done by an aerospace plating company, which unfortunately is no longer in business. The engine mount was masked beforehand and baked afterwards, to prevent those issues. It was done per the relevant specs.

While I was there, I saw a number of other aerospace parts in for similar plating.


David Paule 04-25-2022 07:44 PM

I decided to install the stainless steel fuel line from the firewall to the gascolator, only to find that it didn’t come close to fitting. That was one of the parts I’d made a pattern for while the dummy acrylic firewall was in place. In theory it should fit, but in practice it doesn’t. And that my friends, is the difference between theory and practice. However, other things which I fit the same way, fit just fine. It’s only this one part.

Incidentally, if you haven’t already installed the tiny screws for the tube fittings on an Andair device, do it before you install the device. You’ll be happier. I removed the gascolator, put in the screws and reinstalled it. Andair says to stake the screws and I didn’t do that - I used Permatex Threadlocker Blue instead.

You may have heard that there’s not much room between an RV-3 firewall and the engine. That’s entirely correct.

David Howe’s cowl tool is virtually essential for aligning the cowl. Wirejock, aka Larry Larson, made the necessary disc to replace the spinner. I shortened the length of the tool because my shop is too small for its full length. Here, you can see the full length tool without the disc. I later installed three length adjustment bolts in the empty hub holes - these control the cowl position so that the prop and spinner will fit (I have not ordered these yet).

Even with a heavy book and a water jug resting on the top cowl, it would not lay fair to the fuselage.

I copied Jack Nystrom’s work here on his RV-3, Hack Job, and made several slits in the inner skin. The slits are 10” long. This worked but I’ll need to fill and seal the slits later.

The top cowl fits reasonably well. The bottom cowl was more difficult, mostly because it needed the top cowl to hold it up. At this point, the lower quarter-turn fastener locations are not in, also the cheeks aren’t trimmed to length. But you can see the disk and the shorter length tool.

In that photo, the wide angle lens (did I mention that I have a small shop?) causes distortion in the fuselage.

Under the small potatoes category is the burning question: do the cowl cheek bulkhead flanges face forward or aft? I have 11 photos showing them. Five said flanges aft, and six said flanges forward, which was my inclination anyway. The plans don’t show it, no surprise, and the SK sketches sort of illustrate that either the person drawing it was lazy or the flanges face forward; it could be interpreted either way. On mine, forward they will point. The actual parts are labeled R and L, and if I followed that, they’d point aft.


wcalvert 04-26-2022 08:19 PM

You have discovered the magic of David's cowl fitting jig! It made that part of my build the 'knees ...

"In theory, practice and theory are the same. In practice, they are not" Benjamin Brewster 1882

Words to live by!

David Paule 04-27-2022 11:20 AM

Thanks - I hadn't known the origin of the quote.

Incidentally, here's a look at SK-82, which shows the firewall and cowl. You can see why I commented about either the flange direction or the or the person drawing it.


David Paule 05-14-2022 07:24 PM

Along with the cowl cheek bulkhead flange orientation, there’s another burning question. Do the cowl cheek extensions end at the spar bulkhead as shown in SK-86 or do they extend aft a bit?

I went back into my photo collection and found 15 RV-3s with the cheek extensions ending at or close to the spar bulkhead, 11 ending a short distance aft of that, and 21 ending a long distance aft. Now, without a lot of measuring and calculating, “short” and “long,” as I’m using it here, are probably around 3” and around 6” more or less. And I mean in its most approximate sense. I measured my F-364 pieces and they’d extend aft around a foot, if I didn’t trim them. The front matches the bulkhead curve nicely but the aft end is relatively poorly formed. If I did any trimming, I’d need to rebend the entire part. And if I used them at their current length, I’d need to reform the aft end. You may remember the fun I had bending the bottom aft fuselage skin. Well, these are thinner, a plus, but a much tighter bend, too, which makes it more difficult.

Alternatives are using the RV-4 part, a fiberglass section, which needs to be extended in the front, as a few RV-3s have done or making my own from scratch of fiberglass, as John Nystrom did on his excellent plane. I thought about it and ordered the RV-4 parts from Van’s. These are subject to their wait and ship mode right now and should be in this coming week, but I won’t need to put them on just yet.

I’m supporting the lower cowl with bungees in the back, attached to the cowl by clecoed tabs, and the cowling tool and clamps up front. Here’s the back.

The forward lower cowling has spacers in the cowl tool for spacing.


David Paule 05-26-2022 09:01 AM

The cowl cheek extensions arrived and as expected, they don’t fit my RV-3B. Remember, they are RV-4 parts, so there’s no reason that they should. They are a bit short on width, skin to outboard face, as shown here.

But the overall curve is decent. The best fit seems to be with the flanges trimmed off and the extension’s edges extended a bit and new flanges formed. One idea was to use piano hinges for the flanges.

They’d need twisting but otherwise would work. I’ll need them around the front of the right one in any case for battery access. There’s another facet to that, since that extension’s front flange will interfere with the battery… so more change. But they’d probably want riveting to the fuselage skins along their length if I used them as the sole flanges. With fiberglass, glue and a few keeper rivets should suffice. The piano hinges are anodized and I’m reluctant to bond to that surface, merely for lack of test data to guide me.

The side quarter-turn fasteners needed flanges. I know that a number of builders rivet aluminum strips along the sides for that. I followed DanH’s example and made fiberglass strips for that. Trimming these proved one of the dustier, messier jobs I’d had yet: the strips were at exactly the wrong working height and I didn’t come up with anything better. Still, it's done.

Here are the sides clecoed together where the quarter turn fasteners will be.

And here is the cowl from the front, without the cowl disk but still with the cowl tool on the prop hub. Some work still needed.

Next up is the other airplane’s annual inspection.


David Paule 06-07-2022 07:30 PM

With the certified plane’s annual inspection itself done, I can do a bit of work while waiting for some things to arrive to finish that job.

One thing I did was to caulk the firewall overlay around the cut-outs and edges with the FireBarrier 2000+. I forgot to do that before we hung the engine and it was a bit more difficult now. With the help of a 20 ml hobby syringe, though, it went reasonably smoothly, given my abysmal skill at caulking. My talents, if any, aren’t there.

Finally, I installed the ARP carburetor ice detector in the carburetor and the carburetor on the engine. The carb ice detector is that sensor with the wires in front. It has a probe that goes into the throat and physically senses ice, turning on a light in the cockpit. The device is analog and also turns the light on when the voltage drops, so it doubles as a low-voltage indicator. Yes, it takes a slight bit of interpretation to assess, but in practice that’s been fairly obvious. After all, the first action is to pull on carb heat when the light comes on.

My other plane has one of these and it’s proved its effectiveness over the years. I regard it as essential with a carburetor installation.

I still need to install the throttle fitting and FAB. For that matter, all the engine controls - lots to do!

Had a visitor at the shop recently. Dan Horton stopped it for a look. It was very good to have someone with that level of knowledge and expertise take a look at this project. He gave me some suggestions, showed me areas where baffles are typically poor, and found a decent location for the oil cooler for when I get that far. All in all, it was a very helpful and enjoyable time.

I got to see his RV-8, and the attention to detail was superb. The little things definitely show up and add up. It was clear at a glance that his comments about the large volume engine cooling air inlets are spot on, with zero bugs inside the inlets. The lower landing gear intersection fairing, the tail fairing and the RV-8 wing root fairing were also worth examining. If you ever get a chance to see his plane, be sure to take some time for a close look.


David Paule 06-19-2022 07:25 PM

Before I can do any of the engine stuff, I’ve got to get the cowl into shape. You might remember that the cowl cheek extensions were pending. I received the gray fiberglass RV-4 extensions. And since the RV-4 cowl is longer than the RV-3’s is, the RV-4 cowl tapers closer to the fuselage at the aft end. The extensions are therefore not as high. This led to a decision needed, between the three approaches to fixing this.

I could position the extensions aft far enough that the shape would extend between the aft end of the cowl and the front of the extension, more or less a flat wrap. Here’s how that fits:

Not so great, huh?

Or I could move the extension closer to the cowl and cut off the flanges and make pieces to fill in between the fuselage and the extension:

The final option, suggested by Dan Horton when he was here, is to make new molds and make brand new extensions, as John Nystrom did:

But that strikes me as labor-intensive. I chose to cut off the flanges and make fill pieces. You'll see those below.

Figuring out how to make the battery compartment and its hatch in the righthand extension was interesting. A lot of steps in a certain sequence. Since I was going to have to cut the front of the extension off for the compartment, the aft portion needed a bulkhead. I made a simple form of thin plywood, with packing tape and electrical tape as mold releases - epoxy doesn’t stick to these nor to duct tape.

Here’s the back side of the bulkhead, formed in place, complete with flox fillet.

This is what the front looks like after I pulled off the plywood form. There’s no fillet yet on this side, that’s in a bit.

Before splitting the extension for the hatch, I made an alignment tool so I could regenerate its original joined position.

Before cutting,

It was removed for the cut, of course.

After splitting, I sanded both front and aft parts and taped the forward section so it doesn’t get bonded to the flange.

There are two pieces of electrical tape to get both a wrap around the end and also to delineate the needed extent of the flange, which will simultaneously help hold that bulkhead and support the hatch cover.


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