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Old 01-18-2018, 07:39 PM
kentlik's Avatar
kentlik kentlik is offline
Join Date: Sep 2015
Location: Oregon
Posts: 895

Originally Posted by David Paule View Post
Seems like it's been a long time... in fact it has been.

The things I've done in the last month are small stuff. I'm getting ready to attach the next long side skin, and while it's still off, wanted to do some of the smaller stuff. These are things like riveting those bulkhead flanges that I made to the bulkhead's webs. These are finally done, along with a few less exciting things.

Since I'm waiting on a few things before gluing the side skin (it's the right one this time), I started on the belly skins under the seat. There are two of these, F-322, and they overlap both the spar bulkhead and the seat bulkhead, with two rows of rivets each. Drawing 23 shows most of the rivets, with Drawing 24, section A-A, as a supplement. Still, the rivets between the F-304 bulkhead, that short one in between the two center seat ribs, and the skin aren't mentioned anywhere that I could find. Here's a top view of the seat structure from Drawing 24, showing the bulkhead. Not being the bottom view, the rivets that are shown don't apply to the external skins.

I've been locating and drilling holes in the fuselage frame under the seat and in the skin. The right-hand skin there is now mostly drilled and clecoed. It needs some trimming, and yes, I know not to cut out the skin in the area aft of the rear spar.

I've been going so slowly that I thought a bit of motivation might be appropriate. I know that a lot of us put up photos of similar airplanes or sketches of paint schemes that they like. Other people display model airplanes... the list is long. Since I like, never, pay much attention to self-help posters, it occurred to me that the back cover of the 2017 Van's Aircraft calendar might be just the thing. By the way, friends, that cutaway RV sketch in the background is an early view of an RV-3, just as it should be.

We'll see if it speeds things up.

In case these photos disappear, perhaps the alternate photo hosting might continue to work. Perhaps. Worth a try in that event. Here are duplicates of these images:

Awesome! Watching this build is encouraging!
RV-7A in progress
Private pilot, ASEL!
EAA 105 Chapter 7S3
Bi-annual financial contributor

"The credit belongs to the man who is actually in the arena..." Teddy Roosevelt
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Old 01-23-2018, 08:50 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063

I got a PM asking a) which version of Gflex did I use and b) what about adding aluminum powder to the epoxy and c) what about aluminum shims?

I used the Gflex 655K stuff. It's the thickened variety. I bought, I think, a two quart package. With no additional additives, it doesn't sag on a vertical surface, at least in the thicknesses I've used. It's the right viscosity, right out of the can.

I've tried adding aluminum powder at about 5% to 10% by weight to the mixed epoxy weight, and that did add viscosity (which didn't help anything) but also made the epoxy noticeably more brittle, so I discontinued it. It also seemed to diminish the adhesion. My goal adding it was to make the epoxy have more stiffness in compression, which it did, but wasn't ultimately an overall improvement. Now I use the epoxy straight with no additives.

My mentor will not accept a gap thicker than about .015" without aluminum shims. I try to do the same but that's a difficult thing to control well on sheet aluminum parts. Once in a while, not often, I have a shim on top of another shim. The glue does a good job of keeping these intermediate assemblies in place. In fact, that's where I really like using it: to keep parts in place during bigger assemblies.

In other news, I botched the left-hand belly skin under the seat. There was one rivet which had too small an edge distance. There's a new part on order. That exercise used up the weekend for me.

In the meantime, I'm back to work on the right hand tailcone side skin, prepping the various parts for the bonding operation.

While it's inevitable that the tasks immediately ahead do kind of stand up and wave for my attention, one thing that I'm trying to do is to only work on a few separate things at a time, the fewer the better. One, just one, is ideal. The project feels less complex that way, since I only have a single thing to think about at a time. The shop is easier to work in, too, with less clutter and less chance of losing things.

One thing I wanted to include on the panel is a decent slip indicator, one that's physical like the ones in a turn and bank instrument. But I didn't want one of the huge ones that seem to be available from the major vendors. I ordered an S0093-2 from Rieker, Inc., and it arrived. It's very light and tiny, maybe 2" long and about as big diameter as a pencil. Here's Rieker's stock photo. Mine has a white background. Cute little gadget. The ball is highly dampened - I think it'll work very well.

This, the 8-day clock and the airspeed indicator are the analog devices that will be in the panel. I expect that with these and my old last-century non-electric eyeballs, I could probably get the plane down successfully if the electrons decide they've had enough fun and want to take the rest of the day off. But I do hope that they stay on the job.


Last edited by David Paule : 01-24-2018 at 11:13 AM. Reason: Spelling, wording, grabbing a photo... general clean-up.
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Old 02-04-2018, 01:00 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063

One thing that someone asked about off-line about bonding and using shims, is that yes, of course, each surface of the part-to-shim-to-part joint needs to be properly abraded and cleaned. There's no point otherwise. And don't just take a wag at the epoxy quantities; measure it with a gram scale.

Here's that photo of my slip indicator. The housing is plastic, contributing to the very low weight.

The right-hand tailcone side is now on for the final checking before gluing. There's still some prep to do before I get that far though.

The F-303F strip in the spar bulkhead center section has, for some time, had the AN426AD4 rivets installed. I understood these to attach this piece to the bulkhead pieces, with the AN426AD3 rivets for the skin splice while the skins themselves didn't have these rivets. I looked at the drawing, below, again, since those skins are next, and decided that I was mistaken: the AD4 rivets definitely appear to go through the skins as well as the F-303F strip and the bulkhead halves. I drilled those out and match drilled these holes through the skins, after replacing the left-hand skin because of insufficient rivet edge distance on the previous one.

The area is also shown on detail B-B, Drawing 23. Note that the rivet spacing conflicts with Drawing 11. However, Drawing 23 is all about the skin riveting while Drawing 11 is all about the spar bulkhead. I think that a reasonable interpretation would be that 11 controls the locations of the AD4 rivets and 23 controls the AD3 rivets - but it's conservative to use the closer spacing:

In my case, it's moot - the holes are already drilled.

The seat belly skins are clecoed on now:

The belly skin for the firewall to the spar bulkhead that came with the kit is, for some reason, slightly too short for this fuselage. I'll order a larger one. The forward side skins appear to be the right size.

If these photos have disappeared, try this alternate hosting location:

Here, here, here, here, and yes, here.

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Old 02-04-2018, 09:42 PM
RussellT RussellT is offline
Join Date: May 2016
Location: Albany Western Australia
Posts: 96

At the time (in an previous post) when you mentioned setting those F303 strip rivets I did wonder why you did that, couldn't see that it would compromise anything anyway. I did give my #30 reamer plenty of use when I riveted the floor sheets on mine as the 4 layers that come together here did make hole alignment for easy rivet insertion a little difficult.
Your fuselage is looking very nice Dave, looking forward to seeing it flipped.
RV 3B. Very slow build. Now onto final assembly...
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Old 02-05-2018, 10:39 AM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063

Originally Posted by RussellT View Post
At the time (in an previous post) when you mentioned setting those F303 strip rivets I did wonder why you did that, couldn't see that it would compromise anything anyway.....
I did it because it kept the two spar bulkheads located correctly with respect to each other, sort of as a tooling aid. But in retrospect, that wasn't necessary.

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Old 02-12-2018, 07:19 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063
Default Glued the RH Tailcone Side

I gathered together the same crew as last time, experience counts, and we glued on the right-hand tailcone side today. Like before, we used thickened (this version comes prethickened) G/Flex epoxy along with an exoskeleton framework that will come off when the glue sets far enough.

But that's in the near future.

Today, we spread the glue, put the skin in place, and clecoed on the exoskeleton and filleted the glue along the inside edges of the bulkheads and the longerons against the skins. In fact, that's what Dave is doing in this photo.

After a few hours, while the glue was still tacky, I removed all the clecos and replaced them with fresh ones. The original ones had been oiled so that they wouldn't stick but the replacements weren't.

One of the benefits of adding this overall process, of gluing the skins on, to the general RV construction, is that it provides hours and hours of prep work. It's a good way to absorb excess spare time.

One of the steps before the actual bonding was double-checking that the fuselage is still straight and true in the jig. Got lucky there: it hadn't changed and was still in rig.

If the photo disappears, try looking here.

I'd ordered a new F-321 belly skin and it arrived. My original one from the factory was just a tiny bit short; not knowing whether it was the factory or my particular fuselage, I just ordered a new piece. I ordered 25" x 26" x .040" and it'll clearly fit okay.


Last edited by David Paule : 02-12-2018 at 07:23 PM.
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Old 02-12-2018, 07:53 PM
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jliltd jliltd is offline
Join Date: Sep 2013
Location: Rancho San Lorenzo
Posts: 1,209

David. I have been following your thread here for some time. Really great work. And as a flying RV-3B owner I have perused your photos when working on the bird, in a sort of anatomy book fashion. It's great to see the structural detail when I am doing systems runs and the like.

Your bird is looking to be a stellar example.

Thanks for taking the effort to document things so well.

Jim Ivey
(and a few more airplanes)
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Old 02-14-2018, 11:29 AM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063

The exoskeleton is now off the side. Even without the clecos, it hasn't fallen off the fuselage, so I suppose the magic worked again.

I had made one mistake, though. The exoskeleton at the top longeron, which you'll remember is at the bottom of the inverted fuselage, immediately adjacent to the jig as is the longeron, has some squeeze-out that I didn't remove soon enough. With the exoskeleton off, this flashing was very apparent. Here's a bit of it. It's that tan band under the aluminum.

If I'd trimmed it off the evening we glued it, all would have been fine, but I didn't. I removed it the next morning but it needed a Vixen file.

You can also see some glue that oozed through a rivet hole and another that got filled up. We were a bit generous with the glue, apparently. I don't put a cleco in every hole, since the idea is only to make the surface smooth and hold the skin on in the right position. After I took this photo, I spotted that and it came right off. In any case, cleaning up the rivet holes and countersinks generally is pretty easy.

This side came out better than the left side.

The alternate-hosting site has this photo, too.

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Old 02-28-2018, 07:08 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063

I finally reread the manual for the areas I've been working on. Should have done that earlier, as it would have told me the correct way to assemble that spar bulkhead strip that I had to unrivet. The manual says "The rivet holes through the skins and the bottom flanges of bulkhead F-303 should not be drilled until both skins are in place."

I agree with this with one exception: if you drill through the bulkhead flanges first, then when the skins are in place, you can back-drill through the skins using a 12" bit, and there will be no difficulty locating the holes on the skins. Just watch out for edge distance when you're locating the holes on the flanges and when you set up the skins for drilling.

Also, note that some of the rivets are -4. When you're doing the drilling, if you don't go bigger than #40 at this time, you'll save yourself some time. You can drill those holes to #30 before dimpling. Just don't forget.

I glued the strip on to the flanges. That'll let me remove those clecos during the fitting of the forward belly skin.

A machinist friend made the button at the end of the manual flap handle and cut the slot. The bearing blocks for this are ready now, too. The plans don't show it but the manual correctly says to install nutplates under the bearing block mounting angle to facilitate easier maintenance. Since my seat rib flanges were running low on edge distance (the extruded angle is ample) I made a small plate to rivet the nut

The photo also reveals that the exoskeleton angles for the seat pan skin are done. I had to use my shrinker/stretcher to get the correct curve in these.

Here's a bit of tape that I removed as part of the process when I glued the right side skin on. Clecos protruded through the holes and carried glue along with them. I pulled the tape off and the glue came along with it, nice. Since the clecos themselves would push the tape away, I poked slits through the tape in each of the cleco locations before gluing.

The alternate photo hosting site has these photos, too. The first one and the second one.


Last edited by David Paule : 08-13-2018 at 08:26 PM. Reason: lost the photos. Replaced them.
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Old 03-29-2018, 05:54 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063

The left-hand belly skin under the seat is now glued on. Here it is with the glue curing, the exoskeleton in place, and the tape freshly off. Removing the tape is one of the first things to do after the clecos are in (the first ones are wiping off the cleco tips and filleting any joints).

Then I made the exoskeleton for the right-hand side and did all the prep. As of today, this skin, too, is glued on. This photo shows the same status as the first photo but on the right side. Note that some tape is still on, under the exoskeleton.

While I was close to the details, I resolved to correct a bad area on the very bottom-most longeron just aft of the firewall. I hadn't positioned these correctly on either side. Initially, I thought that shimming them would suffice, but the more I thought about it, the more I leaned towards simply replacing these. Haven't done that yet, but that's coming up on my list.

The arrow shows the gap. This is the left side; the right side is worse.

Alternate photo hosting, in case these photo have disappeared

Here's one,

Here's another,

And if I've done it right, here's the final one.


Last edited by David Paule : 08-13-2018 at 08:30 PM. Reason: lost the photos. Replaced them.
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