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Old 12-02-2016, 02:46 PM
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KatieB KatieB is offline
Join Date: Jun 2010
Location: Shelbyville, TN (KSYI)
Posts: 997

Originally Posted by David Paule View Post

This picture makes me want to run upstairs, dig through my box of rubber-powered scale free-flight plans and build a model airplane!

Wait, I mean... go to the shop and work on my RV-3... yeah
Katie Bosman Krotje
RV-3B wiring in progress
Build log
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Old 12-18-2016, 07:33 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 2,879

I made a pair of bottom firewall gussets, similar to the F-855PP gussets on the RV-8. These are made of .063 2024-T3. The photo shows the right one clecoed on.

Here's the shape I used. It fit both sides with just a little extra; it was a good place to start. I trimmed both slightly after drilling them. Note that they both needed a slight bend.

There's also now a gusset for the top of the firewall frame, too. On the RV-8 that's the F-845PP. I made something that would fit. Here's my RV-3B version:

The numbers indicate the dimensions for the adjacent edge in inches. These also were .063 2024-T3 aluminum, and like the others, required a bit of final trimming and bending to fit.

When I decided to make these, I was following the advice of Randy Lervold and in the footsteps of a number of subsequent builders. Interestingly, though, neither the RV-4 or the Rocket seem to have any similar gussets.

I redid the firewall to spar bulkhead ribs, that on my plane replace the F-312 ribs. I'd made a mistake in a rivet pattern and it was easier to replace them than fix them. This current version also has a mistake - the flange to the bottom skin (on top in the photo) should be pointed outboard rather than inboard. The rudder pedals mount on that flange. I'll add some angle for that purpose and that's why I left some of the rivet holes empty for now.

You can see the clecos in the firewall attachment holes.

Here is what the forward fittings look like.

The photos are independently hosted here, here, here, here, and here. And the last one here.

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Old 01-09-2017, 08:53 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 2,879

The bottom forward longerons are 1 x 1 x 1/8, and the factory shipped two pieces for that. They were labeled F-450 and I didn't think anything about them. I managed to ruin them both, and replaced them from stock. It turns out that unlike the stock angles, the F-450 are special. They've been opened up to fit the bottom skin. On my plane that is only necessary at the aft end, and it should taper to the standard 90 degrees at the forward end. It didn't appear as if the F-450 did taper, it appears, looking at the scrap, as if it had been opened up full length.

I replaced the original ones that were 90 degrees with a pair of new F-450s. They fit just fine. Keep an eye out for them in your kit, if you're building one of these.

In the view of the lower gussets and that lower forward diagonal longeron in the previous posting, you can see that the forward end of that diagonal longeron is outside the firewall fitting. The plans specify that it be inside, but in order to fair to the skin, it either needs to be outside or I'd need a joggle or a shim. Since the lower longeron is the same thickness - and in fact the fitting was positioned for that - outside it is.

The spacing of the flap weldment and its bearing blocks, F-377, is such that the fuselage is about 0.58" wider than needed, so I added a pair of 1/4" plastic spacers:

These have the added benefit of slightly reducing the friction on the weldment, since they reduce the overlap.

With these in place I jiggled the position of the flap weldment assembly to minimize the interference with the longeron (some trimming still required):

Then I drilled the pilot holes for the bearing blocks to the seat rib angle and clecoed them:

Using fairing strips of aluminum, I was able to locate the corner aft bottom pieces of the seat bulkhead. These are sketched in on Drawing 19 and Sketch 43 and have an RV-4 part number, F-407C, which doesn't show up on the RV-3 plans.

Then these got drilled and clecoed, taking care to avoid the rear spar carry-through.

Looking around, it appeared to be time to yank the spar bulkhead out for some of the small work that's been taking my time.

The fuselage sure seems sparse without that, doesn't it?

The photos are also hosted here, here, here, here, here, here, here, and finally, here.

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Old 01-10-2017, 07:29 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 2,879
Default More on Fitting the Flap Weldment

Just wanted to elaborate on fitting the flap weldment. If its too far aft, the forks will interfere with the lower longerons. If it's too far forward, the arms to the forks will rub on inside flanges of the seat bulkhead.

If it's lined up perfectly true in yaw, it's entirely likely that one fork will rub and the other will have satisfactory clearance.

Even when the clearance to the longeron looks ideal, probably the bolt heads for the rod-end bearing inside the forks will interfere with the longerons.

And you might need to trim the seat bulkhead's inside flanges to allow for the assembly's cross-bar.

With all that, the bearing block's mounting bolts still need to have the right positioning for reasonable edge distance on the seat rib's angle - that's why I added those 1/4" plastic shims. This would be a reasonable place to trim down a 1x1x1/16 angle like I did on the upper longerons, so that there's a wider pad for these bolts.

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Old 01-11-2017, 02:27 PM
rvsxer rvsxer is offline
Join Date: May 2007
Location: Inver Grove Hgts, MN
Posts: 172

That is one nice fuselage jig. Is that one of the old "Frey" jigs? I built my RV-6 on the plans-specified wood jig and a Frey jig was but a pipe dream...
Mike Hilger
RV-6 N207AM w/G3X, 1,400 hours +
South St. Paul, MN (KSGS)
Senior Tech - Panel Design, SteinAir, Inc.
A&P, EAA Tech Counselor

We're all here because we're not all there...
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Old 01-11-2017, 03:55 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 2,879

Yes, it is. My use of it on my RV-3B probably starts on post #235. I also put a thread on the jig itself here.

This is an RV-4 jig that I adapted for this purpose. You'll note a few non-red and non-yellow parts which are parts I added. And many of teh yellow cross-members needed to be relocated.

If I were going to ask Mr. Fry for a change, though, it would be to make the jig about 6" higher off the ground. I'm not a tall person and the jig still seems unnecessarily low. I can easily look over the bottom of the fuselage but it's awkward to work near the upper longeron. I suppose Van's jig instructions might have the same issue, since they are about the same height. But to put this in perspective, I don't recollect any of the other builders commenting about this, so you might find it perfectly positioned.

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