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Old 03-02-2016, 10:13 AM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,253

The bottom wing skins have all the solid rivets installed that they'll be getting. David Dalton, a local RV-7A builder, came over and helped on the right inboard skin. Then I did the other three skins myself.

The procedure that worked best, working by myself, was to go from inboard to outboard, one rib bay at a time. I riveted the main spar holes to the next unriveted rib and then worked from the main spar towards the rear spar. Since the leading edge was up in the jig, that meant that I was standing, working downward. I couldn't do the final five rivets close to the aft spar because my arms weren't long enough and although I could reach them, they were too awkward to do reliably. So I left the rear spar rivets and the aft-most five rib holes to be filled with blind rivets.

After I'd completed these, I realized that I could have riveted the rear spar as I did the main spar, doing a couple rivets in each spar and then moving back to the other spar. And I probably could have gotten those five rivets the same way, by sitting on the floor and reaching into the wing. But I didn't think that through until the skins were riveted. Now there's not enough access for that.

Blind rivets it'll be.

While waiting for the blind rivets to arrive, I riveted the -4 rivets that go into the main spar web at the inboard stub end. These five rivets and the adjacent F-303H block are left to the builder. Big hint: do these BEFORE you assemble the spar to the wing frame and it'll be a bit easier. And it won't affect a thing. It'll just be easier.

(If the two photos are gone, try here and here.)

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Old 03-03-2016, 04:50 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,253
Default Two Rules

1. Don't cut or rivet or drill anything until you absolutely have to, because you never know what else might need to be part of that assembly or go there.

2. Cut, drill and rivet the small things early on, because it might be impossible to do them later.

Yeah, these sort of conflict with each other. In fact they make a classic Catch 22. That's the charm of building an RV-3B kit.

Can you spot what's missing in the top photo of the previous post that led me to post this? Hint, it's an RV-3-specific part, the pre-punched kits don't need it.

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Old 03-07-2016, 07:15 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,253

The answer to the question I posed above is that I'm keeping out the doublers for the inspection plates for just a little more access until later.

I finally got to see and sit in a flying RV-3. I hadn't seen one since I got interested in them a few years ago. Scott Taylor let me sit in his. He's a lot bigger than I am so I'm deep into the seat. In mine, I'll be higher.

Or if that photo is unavailable try here.

I made a wood tool to go between the F-303 front and back bulkheads. Unfortunately I picked a windy day and more unfortunately, left the garage door open. I ran the table saw and planer in the driveway and a lot of wood shavings went into the shop. I spent the rest of the afternoon vacuuming the shop.

The F-303H shear blocks get bolted and riveted to the spar web. The bolts go in after the wings are on the fuselage but are needed to locate the rivet holes, which for some reason aren't pre-drilled at the factory. These bolts go through the F-303 bulkhead, the spar web and the F-303H blocks. They fit nicely in the blocks but not at all in the spar web. The holes are slightly too small.

I checked the same holes in the F-303 side pieces and some of the holes let the bolts in but most of them didn't. The manual emphasizes that we shouldn't drill out any of the spar mounting bolts and these clearly don't fit. I looked at them with a 10 power glass and these holes, in the side pieces, are punched, not drilled like the main spar bolt holes - and yet these too need good alignment.

Back to the plans. On drawing 6, the plans just describe the hardware. But on page 11, there's a note to match drill the side pieces to the spar. Imagine that.

Our local hardware store is a good one. They had 1/4" reamers.

I used AN-6 and AN-4 bolts to locate the aft F-303 bulkhead on the left spar, and match-drilled the shear block's holes. The shear block, incidentally, is that cross-wise block of aluminum near the right side of the photo that says "LH" on it. The holes are the two 1/4" holes in it.

And then did the same for the right spar.

Then I clecoed and used some AN-6 bolts for location and match-drilled the front bulkhead to the rear one.

Alternate links to these last three photos are here, here and here.

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Old 03-13-2016, 08:11 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,253
Default No Clecos!

A milestone of sorts, wings with no clecos visible. I've still got to rivet the flap hinge on but that gets done when the wing's in its cradle, which is already out at the hangar. The hangar, you may remember, is where I've been storing all the kit parts and Van's boxes.

Next job was to wrap one wing in moving blankets. Well, moving blankets aren't what they used to be. Here's the left wing with two blankets on, overlapping.

An alternate place to find the photos, if they disappear, is here and here.

There are a number of places in the plans where Van's specifies certain brass bushings. A friend's homebuilt has these and they work reasonably well. Unfortunately Van's didn't bother to include them in the kit. Some time ago, I had a composite trimaran sailboat and I used plastic bushings from on some of the moving parts, and was pleased with both the smooth operation of them and the minimal wear. So I ordered a set of appropriate plastic bushings for my RV-3B from them.

I'll try them out and see how it goes.

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Old 03-20-2016, 06:32 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,253
Default Wings Away!

Wirejock came down from his mountain to help me more the wings to the hangar. It went smoothly enough. After taping moving blankets to the wings beforehand, I put one thin piece of plywood in the pickup truck, then the right wing, blanket side down, then another thin (and therefore light) piece of plywood, and and finally the left wing. Tied them down and off we went, driving carefully.

Of course something had to cause some concern. In this case it was a pine tree in the backyard that had grown up into some power lines. While we were tying the wings in, a neighbor dropped by to tell us that the tree was sparking with the wire. After a brief visit from a fire truck and a call to the power company, we were on the road.

Unloading went smoothly enough. Larry took a photo of me holding a wing in the hangar.

or here.

After we got that done, we went for a flight in my Cessna 180. Very pretty day and he had the controls for most of the flight, mentioning that he hadn't flown locally before and hadn't flown in a couple years. I did my usual bouncy landing and we put the plane away.

Later, I took down the wing jig and put it in the truck for its trip to the airport. I will need it at least once more.


P.S. I checked and the wings took three years to the week. Yikes.

Last edited by David Paule : 03-25-2016 at 07:55 AM. Reason: Added P.S.
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Old 03-20-2016, 08:16 PM
wirejock's Avatar
wirejock wirejock is offline
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 5,097
Default Thank you

Thaks so much for the treat. It was fun moving the wings but the real treat was flying Big Hammer!
Larry Larson
Estes Park, CO
wirejock at yahoo dot com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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Old 03-22-2016, 01:01 PM
Abraham Abraham is offline
Join Date: Mar 2016
Location: Rockland County, NY
Posts: 195

Looks great, I was going to buy a 3 at one point..
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Old 03-22-2016, 03:27 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,253
Default Engine Mount Beef-Up

KatieB sent me a photo of a cracked weld in an RV-3B engine mount at a lower corner where the landing gear socket is welded adjacent to a mount bolt. The crack was visible with dye penetrant. Yes, this was a six-bolt mount.

I thought about what was going on and why that crack should exist, and then added this gusset, the one the arrow points to. It's .090 4130.

I haven't done any stress analysis on it. The gusset is simply a WAG. The welded length of the inboard end of the gusset is about as long as the welded side of one of the adjacent factory gussets.

What I think's happening is that the drag load on the wheel is causing this. It doesn't appear as if there's a great deal of stiffness to the engine mount in a direction that would resist twisting of the socket, and that's one of the load components that a drag load at the wheel would produce. This gusset adds a minor amount of stiffness and some additional strength, particularly across that cracked weld.

Now don't misunderstand me here - I'm not trying to imply that the engine mount is not strong enough as it comes from the box from Van's. All I wanted to do was add some strength in a certain area (yes, I did it on both sides of the plane). So this is what I did for my plane. I'm not making any recommendations.

Future inspections will need to check all the welds in the mount.

Note that the welds are on the top of the gusset, so that any oil in service won't fall into the edge of the gusset that's unwelded (all the gussets are welded only on one side).

If there aren't any photos visible, try here and here.


Last edited by David Paule : 03-22-2016 at 06:06 PM.
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Old 03-22-2016, 04:17 PM
rv8or rv8or is offline
Join Date: Oct 2007
Location: Norwich England
Posts: 187
Default Gusset

I had the same cracks in my RV 3 when I brought it. Noticed this on the pre buy inspection.
Locally I have been involved in 3 RV's a 6 a 4 and my 3 with engine mount cracks.
I know common denominator is my flying. Had to get that one in before someone else did.
We have came to the same conclusion that it is the torsional load, and have strengthened the mount accordingly.

You will enjoy the 3.

RV 8 extremely slow build.
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Old 03-22-2016, 06:07 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,253

Rob, care to share a photo of how you did that?

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