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Old 04-03-2016, 08:56 PM
David Paule David Paule is online now
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,126

This is a busy time of year for me so I haven't gotten much done lately.

The engine mount got painted. Here it is in the primer. You can see my added gussets near the top of the photo, welded across the landing gear socket.

Or if that doesn't show up, try here.

Since then it's been painted white. I used Dupli-Color Engine Enamel rattle-can. It seems to be a decent paint but I've already scraped it in a couple places so we'll see.

I reamed the mounting holes to 3/8".

I had a bad F-303A part, one of the four upright side pieces that go into the assembly of the spar bulkhead. I called Van's on that, sent them a photo and offered to buy a good one from them since it's been four years since I ordered the kit. Van's graciously sent me a replacement part for free.

Darn good service - thanks, Van's!

While I was placing the order, I ordered a firewall recess kit. I figured I'd get a sheet of stainless steel and a poorly-copied page of instructions. Instead, to my delight, I received a fully-formed and punched recess, complete but for some rivets, and of good quality.

I'm changing the design of the F-312 parts that extend aft from the center engine mount bolts. As designed, these do not attach to the spar bulkhead. In the RV-4 plans, the equivalent parts do attach, and I felt that was a better design. I'm not doing it exactly like the RV-4 so I spent the work time I had today coming up with the details and making a couple of the angles which will rivet to the F-303 web for this. I had to work up the geometry and figure out the assembly sequence.

Bruce, when you called, I didn't get your contact information. Would you please call back when it's convenient? Thanks.

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Old 04-08-2016, 04:50 AM
rv8or rv8or is offline
Join Date: Oct 2007
Location: Norwich England
Posts: 182
Default Engine mount

Sent a pm
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Old 04-08-2016, 01:15 PM
David Paule David Paule is online now
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,126

Rob wrote in and sent me this photo along with this comment:

"In the photograph which was taken during my pre buy inspection you can see the crack.

The red dotted line is the gusset that was welded onto the mount. This gusset necessitated running the brake lines up the front of the gear leg which was no problem. Now that I have seen your mod I wish I had added that also. We did a similar mod to mine on the RV 4, but on the RV 6 we ran another tube from the front of the leg tube to the attachment points in the middle of the firewall to reduce the torque loading as well as gussets similar to the ones dotted in red below."

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Old 04-11-2016, 07:58 PM
David Paule David Paule is online now
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,126

I've been deburring the various bulkheads and have found a few small issues. I've got a query in to Van's for these but thought that you might be interested in seeing them.

The seat rib bulkheads have narrow flanges on the seat pan side. Here's the narrowest, on an F-314. The others aren't as narrow.

Here's more of an overview:

It looks as if there are supposed to be three places where I need to drill some holes. Forward is to the left. The left-most hole location is for the aileron pushrod and is in the plans. The middle hole is shown in an isometric sketch in the plans, and the right-most hole isn't shown at all. I'm happy to have the opportunity to save a few grams but wonder about the deformation of these ribs in a crash with the holes in place.

The firewall, which incidentally came with pre-punched or drilled pilot holes for the engine mount bolts, has curiously crude side flanges, even for an RV-3B. Anyone encountered this before? How about the shallow return lip?


I decided to make a pass-through hole through the spar bulkhead webs for electrical and pitot-static lines, so that I could leave those in place if I pulled the wings off. I haven't made the equivalent holes at the ends of the spar webs yet. The hole is 1 3/8" diameter, mostly because I had a hole saw that size. The flanges are .040, thicker than the .032 web, mostly because I didn't want to do a structural analysis. I later added six rivet holes per doubler.

Finally, as I was deburring parts, I came across the elevator bellcrank, F-339. Except that it wasn't F-339, in my kit, it was F-635, a nicely pre-punched part that Van's kindly included in the kit. Since I couldn't deburr it without separating it into its three pieces, I decided to enjoy the luxury, fleeting as it was, of building a pre-punched assembly.

If those photos aren't visible, try here, here, here, here, here, and here.

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Old 04-19-2016, 08:53 PM
David Paule David Paule is online now
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,126

Van's basically said:

For the narrow flanges, adjust the rivet spacing to fit.

Drill the lightening holes. (Done.)

The firewall flanges are supposed to be flat, not with the return lip. (Done.)

The front flanges of the seat ribs, F-314 and F-315, need to be cut off. Haven't done that yet.

Van's tosses in RV-4 parts here and there without bothering to update the plans. The tailwheel spring mounting bracket, F-309, is actually F-409 and while it can be trimmed slightly it looks as if it'll fit as-is, although the spacing of the aft two bulkheads will need to be adjusted slightly to suit.

The seat bulkhead top, F-305B became F-407B. I know there are others and will try to point them out as I come to them.

The various pieces are deburred and mostly ready to attempt to assemble them into a fuselage. The F-303 spar bulkhead front and back parts are assembled to the spar simulator:

Time to set up the Fry Jig. This will be especially fun because the jig is for an RV-4 and this is an RV-3. Plus I already know that much of the hardware is missing. On the plus side, I've got a set of instructions for this particular model of jig so I know how it's supposed to go together.

I brought the jig home from the hangar and it's been in the shop, folded. It's much easier to work around folded, and much less useful as a jig that way.

The instructions suggest placing the jig on its side and unfolding it. I rolled it outside and and unfolded it there and brought it back into the shop. It was totally manageable. Here it is unfolded. Yikes, that thing dominates the shop! This is going to be a skosh awkward.

Here are the bits and pieces that came with it. I already know that most of the hardware is missing and will try to buy replacements as I learn what I need.

If those photos aren't visible, try
and here.

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Old 04-23-2016, 09:12 PM
David Paule David Paule is online now
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,126

Lining up the jig and figuring out how to line up the firewall is interesting. One of the things that make it interesting is that the jig is an RV-4 jig and thus wasn't intended for an RV-3. Another is that the firewall itself is not the most precise part of the kit.

The firewall came pre-punched for the corner engine mount holes but not the more recent 5th and 6th mount bolts. Since this is an RV-3, I'm suspicious of shape and alignment of factory parts and checked and:

a) The 4 holes weren't square and true to a rectangular pattern,

b) They didn't - any of them - match the plans locations,

c) They didn't - any of them - match the engine mount bushings,

d) The firewall itself didn't match the plans layout dimensions. It wasn't too bad near the bottom but was narrow at the top.

I drew a full-size firewall pattern on a large piece of paper and moved the firewall around on that to obtain a "best fit" location. Then I transferred the vertical centerline from the drawing to the firewall.

Putting the engine mount on the firewall, I adjusted it so that the bottom tube lined up with the bottom flange of the firewall. The bottom flange is about 0.2 degrees off from perpendicular to the centerline, though. I marked this mount/firewall location to identify where the holes should go.

The firewall holes are 3/16 diameter and can all be moved to suit.

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Old 04-26-2016, 08:44 PM
David Paule David Paule is online now
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,126
Default The Engine Runs!

Went out to the engine shop today to watch the first run. The first run in Colorado and the first in over a dozen years. My new but long-stored engine had previously only had a short factory run-in.

For the history, please see posts #31 and #220. The engine was built in 2002 or 2003, factory preserved, and sat until now. As you might guess, I was quite interested to find out what it was like inside, and swapping the factory 8.1:1 pistons with 9:1 gave us that opportunity to look and see. Joe, the engine guy, said it was "very good" inside.

This shop installed a pair of P-Mags with auto plugs, 9:1 pistons, a tiny lightweight Sky-Tech XLT starter, a fuel pump, the carburetor, B&C alternator and some of the adaptation for the constant speed prop. Not all, though, since the test club for this run was a fixed-pitch.

or here.

The run only lasted a few minutes and never got above 1,600 rpm. The engine started on the first or second compression stroke and was running before I expected it to be.

Everything was fine.

It was worth the trip to Greeley, CO.


Last edited by David Paule : 04-26-2016 at 08:47 PM.
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Old 04-26-2016, 09:30 PM
rockwoodrv9 rockwoodrv9 is offline
Join Date: Dec 2011
Location: Meridian ID, Aspen CO, Okemos MI
Posts: 2,916

I think my smile is as big as yours!
Williamston MI
O-320 D2A
Flying N376E
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Old 04-26-2016, 11:07 PM
KatieB's Avatar
KatieB KatieB is offline
Join Date: Jun 2010
Location: Belton, MO
Posts: 1,145
Default IT'S ALIVE!

Congrats on the engine run! I only hope mine goes that well...
Katie Bosman
EAA Homebuilt Aircraft Council
Rebuilt most of SNF tornado victim RV-3B Tony Boy II (had to sell him, but he's flying!)
VAF Dues Paid 2021!
Thoughts & opinions expressed here are my own, and not those of my employer.
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Old 05-01-2016, 03:07 PM
David Paule David Paule is online now
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,126

I'm slowly working on getting the fuselage jig ready. Like the jig outlined on SK-39, the Fry jig intends for the firewall to be mounted 3/4 inch from the support members. David Howe advised me that this doesn't leave enough room to easily get in for riveting, and to increase it to something like 4 inches.

Here's my first pass at stand-offs. Riveted aluminum, they suffered from a distinct lack of precision between the two ends, for both position and parallelism. One issue is that the angles weren't 90 degrees, hence the bend in the post. Their chief advantage is that they only needed short bolts at the ends.

You can see that due to the gusset on the frame, that I needed either the 3/4 inch stand-offs or ones around 6 inches. With any length in between, the firewall won't fit.

The second version was surprisingly easy to build. I trimmed some tubing to just under 6 inches, and cut some 1 inch holes in some plywood using a hole saw. That gave me the centers, which in this case had nicely centered 1/4" holes from the pilot drill. Using some of that excellent G-flex epoxy (I like the thickened kind, p/n 655), I glued them in to the tubes. They are slightly under-flush so that there's no possibility of them affecting the trueness of the ends.

Then I ran some threaded rod through the stand-offs and put a fender washer on the end just to have something to screw the nut down to. This will work.

I don't have a lathe or mill, but my disk sander has a bed that's true. It was a simple thing to sand these with true ends. The lengths are within less than .025 from the longest to the shortest - good enough, I think.

Next up was re-inventorying the aluminum angle. There's a lot of that. It'll be easy to identify the raw material for the different parts.

SK-39 shows some dimensions that don't seem to correspond well to what drawing 21 shows. I'm going to tweak the jig (it needs adjusting in any event, being designed for an RV-4) to match drawing 21. In the sketch, it's the red dimensions,

and on the drawing, the green ones. Note that the jig holds the fuselage upside down, and that the front is to the right in the sketch above, and upright and to the left in the drawing below.

I think this is just another RV-3 thing but if there's something I'm missing, someone please let me know, okay? -- Thanks!

If that photo link fails, try here, here, here, here, and here.

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