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RV-3B Dave's in Colorado

I've been getting the smaller details completed. The gussets at the forward (middle of the image) ends of the baggage compartment ribs that are on the far right needed to be riveted to the seat baggage bulkhead. Here I've got the left one clecoed and am using a .063 plate to ensure that the right one is fair to the seat bulkhead while I drilled the flange.

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I worked my way aft, bulkhead by bulkhead, deburring and priming parts. The aft-most two bulkheads, F-310 and F-311 make an assembly with the tailspring mount. They'd been lined up and clecoed. I drilled them out to 1/4" and installed temporary bolts. Then I removed it and put it on the table for its portrait.

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Later, I disassembled and primed the parts. They are now reinstalled.

At that point, I removed the top longerons for deburring and priming. These support the fuselage frame on the Fry jig. After they got detailed, I reinstalled them and clecoed it all together. Before checking the overall rig of the fuselage, I decided to recheck the trueness of the Fry jig itself. In the photo I've got the SmartTool digital level showing that the jig is level crosswise. This is looking up (the fuselage is upside down) and aft from the firewall through the forward tunnel area.

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The jig is good to 0.1 degrees, which is nice but not great. In a couple cases one direction of the level would show 0.1 degrees and the other direction would show 0.0. I figured that in these cases the angle was about 0.05 degrees. There were two diagonal corners that were slightly out of alignment out of the six total adjustment screws. Two of them, two that didn't need adjustment, can be seen in the photo. It wasn't hard to figure out that I could straighten the jig in roll with only one screw, if the out-of-true were small, without changing the pitch level in any measurable way. After a short bit of work, the jig was again true.

My garage floor is built upon a moving clay base. It's not surprising that the floor shifted. At least that's my hypothesis for the Fry jig going slightly out of true.

The photos are also hosted here, here and here.

Dave
 
Waiter, There's a Hole in My Airplane

Not that long ago, I went out to the shop and encountered this dismaying view.

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Had to do something about that. It seemed best to work from the center out, so after riveting the F-304 bulkhead to the F-313 center seat rib, I riveted the seat rib to the F-305 bulkhead.

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Next came the middle non-center seat ribs, the F-314 ribs. These have the mixer mounting bracket attached, so I had to rivet those on first. After attaching these to the fuselage, I had this.

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Then I clecoed in the outer seat ribs, the F-315 ones. Guess what? There are a couple rows of rivets which are buried in the F-303 spar bulkhead. I forgot about these when I riveted on that bottom splice strip, the blue one just above the marked holes in the photo. Oops.

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I've taped some rivets in place for these and arranged for someone to come out and give me a hand with these. I think that they can be back-riveted. We'll see.

The proper sequence would have been to back rivet these to the bulkhead before I riveted on that splice strip.

In other news, a friend sent me some 1/8" pitot-static tubing - thanks! I already had some 1/4" tubing. This shows both sizes. The 1/8" tubing is MUCH easier to fiddle with. The SB187-2 plastic bushings that Van's sells fits it perfectly, and McMaster sells a variety of fittings for the skinny line. The pitot line in the left wing is 1/4" and I'll leave that; it'll join at a tee.

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If the photos have disappeared, try the ones hosted at a different site:

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Dave
 
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While I was waiting on my helper, I got busy with the rudder pedals. The rudder pedals come pre-welded and the brake pedals need some fabrication and assembly. The plans show the shapes, leaving a few dimensions to our imagination, so I built a set of the side pieces to the plans. They didn't fit, with the brake pedals interfering with the top forward corner of the rudder pedals. Yes, I know that a properly maintained brake system would be stiff enough that the brake pedal probably wouldn't contact the rudder pedal, but it's so close! In my drawing, I've moved it out of the way; the as-built assembly had issues.

I'm old school and used paper and pencil to work out some new geometry, similar to the original. I taped it into my project book.

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Here are the pedals all clecoed up with the new sides on. I didn't get ny photos of the original.

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Here's a better view of the new side plates, including a few efforts to make them lighter.

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Interestingly, on the RV-3B, if I used a single long bolt for the floor-mounted rudder pedal itself, the rudder pedal would become non-removable, due to the other things near it. And if I used it on the brake pedal, my foot would be resting on the bolt shank rather than the rudder pedal bar, since this pivot is in front of it. The plans, it's worth noting, call for individual bolts and screws, not the long ones - the plans have it right.

I was going to order long bolts for these as people have recommended, when I realized these issues. Gotta love the -3!

The screws, by the way, are on the plans but not included in the kit.

I've purchased plenty of hardware and aluminum that's not in the kit because this is an RV-3 and practically everything is a size off or a hole off or something, so I just buy some extra hardware. Matter of fact, I put in an order tonight for some more. Worst case, I might enough left over afterwards to build another airplane. In fact, I was looking for some parts that are clearly (well, not that clearly) shown in the plans, and they not only weren't on The List, they weren't in the inventory list that came with the kit, either, at least not the fuselage kit. Somehow Van's overlooked them. These were the F-355 and F-356 rudder pedal links to the cables and the pushrod inside the manual flap handle. If I remember rightly, the F-356 is also one of the tunnel pieces. There are other instances of duplicated part numbers here and there, either to encourage us to keep our wits about, or to make us lose them. I'm not sure which.

For some reason the Imagebam.com photos didn't load this morning. Perhaps they'll follow.

Dave
 
Dave, you're bringing back fond memories for me. The fuselage skeleton section was my favorite part of the build. I just completed a major home renovation and it felt like finger painting relative to the complexity of the 3. Keep up the good work!
 
Moving along to the flap handle, another assembly that can be made now, I had the idea of using an RV-12 part, VA-110, for my RV-3B manual flap handle button. I called tech support to see if it would fit and was told that the size would be the same as for the -3 because they wouldn't change something like that. Hah! But the support guy was good enough to check it for me, and found that in fact the -12 part was too big and wouldn't fit. No surprise, really.

Riveting assistance for those rivets in the red oval above arrived in the form of Glenn Potter, an AI and excellent sheet metal guy. Here's Glenn taping the surrounding structure.

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We tried using a bucking bar as a back-rivet set but it was difficult to hit the stem of the rivet and keep it straight. Glenn had me move the gun and the T-shaped rivet set to the head of the rivet and drive it from there. Here's me getting set up.

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After a fair bit of hassle, we got it done.

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After we got those eight rivets done, Glenn inspected the fuselage. He's not a Tech Counselor but as an AI and long-time sheet metal man, he's plenty experienced. He found a couple small problems, including one over-set rivet in an easy-to-get-to area. I've already fixed one of these and will do the other one when I get back to the project.

The flap arms with bolts need just a bit of clearance at the lower longerons. This is at least the third RV-3B that needed tweaking that I know of. One of the other two bent the arms and the other also trimmed the longeron.

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This excerpt from the plans, drawing 30, shows the part of the flap mechanism that interferes with the longeron, on the right of the picture. Remember that the bolt head sticks out farther than the arm itself, but both the bolt head and the tip of the arm need relief.

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The flap latch is shown on the left of the picture. It's straight-forward enough except for one interesting detail - the zero line isn't dimensioned with respect to the seat. First I thought about that and then I checked the manual. I was glad that we agreed: first adjust the flap handle to get a good position and THEN locate the position of the notches.

I determined an approximate position with the flap lever in place.

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The blue bracket clamped to the angle in the background is a first hack on the manual trim handle mount. Van's sent me the F-342 and an F-454, the RV-3 and the RV-4 parts. The fore/aft position will be determined later like the flap handle, when I have a cockpit to furnish, and I'll decide then which I want. This one is slightly longer than than the RV-3 one. It's here mostly to decide where to drill the bulkhead holes for the trim cable.

Using the flap handle position shown in the photo, I made a template for where I think it'll all go. But I won't proceed with finalizing the latch position until later.

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I've been averaging about 600 hours per year working on this project since I started. In the last few days, I passed 3,000 hours. I'm not fast and frankly, I'm not all that good at this. But there it is.

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

Dave
 
Seat Rib & Side Plate

Dave,
before starting the wing construction I decided to build the center section. What happened is, that I riveted the outer seat rib positions :mad:. Drilling these rivets out should not be a problem . Furthermore I riveted the F-303 E-1 Side Plate. Do you think I have to remove it also?
When you riveted the seat rib to the center section, wasn't it possible to insert a heavy bucking bar into the spar gap, driving the manufactured head from the seat rib side? Maybe I misinterpreted your description.

Peter





 
Long Bolts for your pedals..

Dave,

I was thinking about your space issue with the long bolts. Would it be possible to use a piece of threaded rod with 4 bolts instead? It would allow you to slide it into place using the space you have available, moving the bolts up and down the threads, as needed, then securing it all into place.
 
Peter, at a minimum, you'll have to remove the rivets in both the red and blue ovals. Both of those go through the F-315 seat ribs, at least on my plane.

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Ideally, with the bottom strip out, we could have installed the seat rib by back-riveting it when we made the aft bulkhead.

The main problem I had was that I didn't have an offset back-rivet set. If I had been able to get square on the rivet stem, I would have back-riveted the red oval rivets using a bucking bar for the back-rivet plate, as you describe. But with my tools that wasn't possible; the rivet would lean over and be unrecoverable. Glenn suggested hitting the factory head with my T set and I did that. The T set was just barely able to reach in far enough. You can see the force I'm pressing with in an effort to get enough access. It wasn't easy. And even at that, it was good that I had an expert on the bucking bar to keep the rivet shop heads straight. He had to work at it.

This tool might work but I don't have one (yet). Bent-end set from The Yard Store.

This worked but just barely: T set from The Yard Store.

Unfortunately, my tungsten bucking bar only has square ends. If I'd had one with an angled end, that would have been lots better.

Amazing - all this way and I still get to buy some more tools.

Mike, that might work but I'm not going to do that. I'll give the as-designed hardware a try since a lot of RV-3s are out there successfully using that hardware.

Dave
 
The forward firewall ribs, my version of the F-312 ones, needed holes for the fuel lines, so I cut those and installed doublers.

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You might remember that I used two back-to back bulkheads for the aft-most two, F-310 and F-311. This was a modification. The tailspring fitting that is included in the kit is from the RV-4 and is a bit larger than the RV-3 design so I jiggled it around until it fit. The issue is that the side flanges are too wide to fit in between the forward-facing flanges of the F-311 bulkhead that I added.

Like all modifications, there are after-effects and ramifications. What I should have done was to weld some new flanges to the fitting and then whack off the original ones. That would have been the smart move, and even after I'd seen that done, I didn't fully understand it.

What I did was to mount the tailspring fitting higher in the aft-fuselage than the plans called for, by about 3/4 inch. In the photo, that's lower since the fuselage is upside down now. The additional bulkheads are the ones to the left.

This gave me a couple new issues. One is that there's no way to buck any rivets (and in at least one location, to even insert a rivet) through the skin and the bulkhead flange because the tailspring fitting's flange is too close to the skin. The other is that the aft part of the tailspring fitting is used to also hold the lower vertical stabilizer mounting bolts.

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The first issue can perhaps be handled by using some Cherry blind rivets there, in at least one of the locations.

The second forces the vertical stabilizer and rudder to migrate higher by that same 3/4 inch. On one hand, that preserves the clearance between the bottom of the rudder and the tailwheel assembly, so that part's good. And while the empennage fairing will have to be redone for this, the word is that the RV-3 fairing pretty much needs some gross rework in any case -- so that's not a new problem. There's a minor structural issue because the upper vertical stabilizer spar mount also needs to move up by that 3/4" distance to keep the same spar-bending moment on the joint (otherwise it would have 3/4" more span and therefore more bending moment, you see, because it sticks up higher).

There's going to be a fit issue at the forward vertical stabilizer mount but it's too soon to assess that.

I made a full-size drawing of the actual as-built fuselage geometry to sort through these things. A friend had given me a partial roll of brown floor-covering paper and I've been using that all through this kit. It sure is a help! Thanks, Rob.

Then an issue that my mentor had pointed out came up, where to put the holes in the bulkheads for the rudder cable? They definitely needed moving, if only slightly, because the rudder horn will be higher. The plans call for the holes to run fairly close to the outsides of the bulkheads.

I clamped the rudder pedals and their mounts in place.

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I decided to run them in a straight line in the up and down plane, and follow the bulkhead edges in the other. This keeps the cable clear of me, a good thing, and tends to minimize the friction.

Here is a long AN3 bolt that I used to carry the rudder pedal position outside the fuselage.

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Then I located the height of the cables.

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Finally I drilled the holes.

Moving on to the manual trim cable, there are two two control mounts included in my kit, an RV-3 one and an RV-4 one. The RV-3 one is larger than the plans says, and the RV-4 one is smaller. I've clamped the larger one in place for this. You can also see one of the rudder cable bushing holes.

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Here's the tentative routing path aft, subject to some adjustment.

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I tweaked the cable path after this photo to ensure that the trim cable would not interfere with the rudder cable and would be positioned to carry it to the elevator. Then I located the holes in the bulkheads except for F-309, and drilled them. Since they are indistinguishable from the rudder cable holes, being the same 5/8" diameter, I labeled them.

The photos are also hosted elsewhere:
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Dave
 
After locating and drilling some holes in the bulkheads for the pitot-static lines and the ADAHRS cable, I decided that a cable clip would be a good idea under the baggage floor. Here's the clip all by itself.

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Then I decided that the plastic bushing wouldn't be in the way, and popped that in.

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I'd previously made and located and drilled the brackets that hold the rudder pedals on, and these were held on by clecos. I couldn't rivet them because the belly skin rivets needed to go through those same holes. So I drilled and countersunk for a couple of keeper rivets on each bracket. Now the brackets are in place and ready for some belly skin.

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You can see the way I handled the fact that the outboard brackets overlap the firewall brackets. I simple cut away the base of the rudder pedal angle brackets there and let the working flanges cantilever out over the firewall brackets.

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The longerons are mostly held to the bulkheads by keeper rivets right now.

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

Dave
 
Skin in the Game

According to other builder reports, the aft-most bottom fuselage skin is especially difficult. It's thick at .040 and arrives poorly bent. Mine was no exception. I spent some time attempting to unbend the bends that were in the wrong place, and rebend the skin with bends in the right places.

One thing that makes the aft portion, around F-311, easier, I've read, is making the slot for the tailspring mount to protrude. Remember that mine is a bit higher than standard? In my case, it looks as if it'll be completely covered by the skin -- so no relief there. No access slot required.

Unfortunately I didn't take photos of the as-received condition.

After working at it a couple days, here is the skin resting on the F-309 bulkhead, the most forward bulkhead this skin covers.

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Here is the skin resting on the F-311 bulkhead, the aft one with the tailspring mount.

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It appears as if, with a bit of help, this connection will fit reasonably well.

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Here are the tools I've been using to unbend and rebend the skin. The table is an essential part of the tool assortment.

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I continued to work on it, and today I was able to make a first attempt at clamping the skin on.

Here's the F-309 bulkhead.

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I moved my collection of aluminum angle so that I could get under the fuselage jig, poked my head into the innards (this is the first time the fuselage has had innards to poke my head into) and took a photo of the skin resting on bulkhead F-310. There's still work to be done.

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At the back, though, it fits pretty decently.

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The fit at F-310 needs some work. A friend suggested driving over it with my truck and after working on it for a few days, I believe that just might be necessary. But before I resort to something that extreme, I'll think about it for a while. Remember that so far I haven't added straps. They'll probably help, of course. I made a couple Howe Fittings (review the wing skin postings for those nifty strap partners) and have a couple more to make, and might think of something else.

Kind of hope so.

The pictures are also posted here, here, here, here, here, here and here.

Dave
 
Lots of fun to be had with the bottom skins Dave (especially the hard to work 40 thou), I struggled with mine too but it eventually concedes defeat and once riveted on looks quite OK. The large rear bottom skin also needed to be massaged similarly to improve the fit.
Get used to climbing in and out from under your jig....

Your under baggage floor cable clips are neat, did you consider using conduit under the floor which is called to be secured with pop rivets I think? Nice work Though.

My current status, If I get the canopy sorted be the end of this year it will have been a good year, I can see why most choose tip overs on the 3.

Cheers, Russell

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Russell, I did consider conduit a long time ago, and decided that since I have no plans for redoing the electronics every few years, bushings would suffice. In this case, I'll have the cable and pitot static lines in before the floor goes on.

There's no conduit on the plane.

Yours definitely looks like it's progressing - super!

Dave
 
Bottom Aft Skin Games

While I was working with the aft bottom skin on my RV-3B's fuselage, I got to a point where I wanted to remove the blue vinyl.

So I did. Under it, the aluminum was translucent. It was a total surprise. I can't figure out how Van's did that. I've never seen aluminum do that before.

I kind of like it. What do you think?

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Ok, I missed the first of April. Meant to post it then. What happened was that I bought a sheet of .020 polycarbinate and didn't bother to strip it's protective coating off, any more than I have the skin. I rough-trimmed it and clamped it in place so that I could easily assess the underlying fit of the bulkheads and longerons. It didn't work out so well, the polycarb being a bit too flexible for the job.

Incidentally, I bought sheets of .010, .015, .020 and .030. Of these, this was the closest thickness to optimal and I could cut it with scissors.

The main area that needed more bending was the bottom center at F-310, the second bulkhead from the tail. After a number of approaches that didn't work out, I found one that did, and succeeded in bending this area a bit more.

Here's the basic idea. I clamped pieces of 1/2" plywood to the sides to protect the skin, and used the darker steel clamp to mostly squeeze the sides of the skin. The steel clamp by itself didn't bend the skin much, plus as the sides bent in, the clamp started to wander closer to the edges. So I added the orange clamp closer to the area I needed to bend more. That did the job nicely.

At the F-310 bulkhead location, the dimension between the plywood pieces when the skin was maximally clamped was about 1.85 inches. This gave me a bend that closely matched the bulkhead. I'd previously tweaked the existing curves a bit, which definitely helped.

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I didn't want to squeeze the aft end too much, so I placed this piece of dowel there, clamping it at the forward end of the skin. I should have also clamped it at the aft end but the fit at the tail is pretty good as it is now.

The short piece of plywood led to a skin ding. The plywood was simply too short and I should have caught that.

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The ding is easily small enough to fill later. A wide friend of mine had a saying: "If you want it like downtown, take it downtown." So instead I took this skin to a local auto body shop, where they bumped it out for me.

Here's a view of the F-310 bulkhead with the skin clamped in place. We're looking at the forward bulkhead, since I've paired two of the bulkheads (the plans only specify one of the pair and I put two there, back to back). There's a substantial gap which I get to deal with. The aft flanges (the flanges at the rear of the pair face aft) actually fit reasonably well.

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

Dave
 
The aft bottom skin passed a small milestone last night. The clamps came off.

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Remembering that the aft two bulkheads are doubled up, you'll realize that I've only drilled and clecoed one for each pair. So far. What's going on is that there are some gaps between the flanges for the forward of both the two bulkheads and the skin, and I don't want to drill those until I've got shims in there.

Since the bulkhead pairs are glued to each other, front to back, I can't simply take the flanges off and rivet new ones on. I'd ordered several F-803CPP for just that eventuality and they were on hand. These are the strips that make a perimeter flange for the RV-8 instrument panel; they'll probably do the same job for mine. I'll actually need to shim these gaps.

It's a subtle thing, but the tailspring mount is not attached at the moment. The way I located the skin/flange holes was to first drill the bulkhead and longeron flanges and then back-drill through the skin. That wasn't much fun. I needed both a right-angle drill and separately, a 12" bit for my regular drill, to get most of the holes. Four were blocked by the tailspring mount, so I removed it.

Note that after the skin is riveted on, the tailspring mount isn't removable without replacing the skin - it's got to be right when it's finally bolted in place.

After the mount was gone, it was possible to drill those holes. Since I expect to use Cherrymax blind rivets here, setting them should not present a problem; there's room to get them in.

Also, there's a hole in the skin that I still need to drill for access to the tailspring attachment bolt's nut. And lots of trimming, of course.

That photo is also located here.

As I mentioned on Vlad's thread about getting a new camera, I did too. The new one has an articulating screen, and while it's not absolutely necessary if you're young and flexible, I've got to say that it's a nice luxury to have now. I took a set of photos showing the various flanges and their gaps, and as I measure the gaps, I'll note them on some prints I made.

Worth mentioning is that I didn't need to strap down this skin, just plenty of time working at it. I was so sure I would, I'd even made a set of Howe Fittings to do that.

Dave
 
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I measured the flange spots where I needed shims and made the shims. Then I gathered together my tools: plastic ups for clean water and soapy water, plenty of small squares of paper towels, Scotchbrite pad, some cards for mixing epoxy and a bunch of popsicle sticks. Oh, yeah, and the West Systems thickened G/flex epoxy and the aluminum powder.

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I mixed up some of the epoxy and mixed in some of the aluminum powder. The epoxy was already, without the powder, thick enough so it wouldn't flow - but it will creep before curing. Adding the aluminum powder made the cured epoxy stiffer and the wet epoxy thicker. THis shows my mixing cards after the job was done.

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I glued the shims to the flanges of the F-310 and F-311 bulkheads in two passes, because I didn't know how long it would take. The first pass was the aft four shims. This took right around an hour. First I cleaned and abraded all the shims and then the flanges. After that was done, I mixed up the epoxy, applied it, and clamped the shims in place. I wasn't too worried about squeezing out all the epoxy because I knew that the powder would give me a minimum thickness, plus some unavoidable mismatches in the flanges and shims (most of them slightly curved) would cause thicker sections of epoxy too.

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Later I went back to do the front-most shims on the F-310 bulkhead. Same affair except that some of these took two pieces of aluminum to build up the thickness, resulting in more time for this job. The cleaning is good for two hours, and I was easily inside that. The pot life of the epoxy is 45 minutes and that was close. One of these little shins, a piece roughly 9/16 inch square, jumped out of my hand and escaped. It's probably south of the border right now; it sure doesn't seem to be in the shop. I made a replacement that was more cooperative.

Here are the F-310 shims. The ones on the right side of the bulkhead in the photo were done in this pass. You can pretty clearly see a couple of instances of places where the shims are doubled.

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On the left side of the bulkhead, the aft side, at the bottom, the one shim that's visible is from the previous pass at this. The glue had cured enough that I could release the clamp. Q-tips, a generous amount of them, did a reasonably decent job removing squeeze-out and smears.

I anticipate that I might need to file down some of these if they end up too thick. I don't have a good idea of what the final glue line will turn out to be.

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

Dave
 
Marked and trimmed the F-326 aft bottom fuselage skin so that I can start fitting the larger tailcone bottom skin F-325.

As soon as the aft skin was trimmed, I remembered that the F-325 skin had a reputation for being slightly short. Mine is no exception. And if I'd left the F-326 aft skin longer in front, and there was room for that, I could have attached the F-325 to the extended part of F-326 -- and now I can't. It'll have to share the F-309 bulkhead rivets and somehow work with the too-short F-325.

Here's a photo marking the aft edge of the aft skin. I used a laser torpedo level on my camera's tripod to locate the cut line. I left it slightly long so that I could do a final trim later after the side skins are on and the vertical stabilizer is on.

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I got a new Aerolab gascolator yesterday. Here's what the filter looks like, on the left, compared to the Andair, on the right. The shells are included too so you can get in idea of the overall size.

On the Aerolab one, the filter and filter housing shown closer to the camera drop down out of the belly of the airplane. There are no service items inside the airplane, and since the gascolator has that red locking feature, no safety wire is needed.

On the Andair one, the part fixed to the airplane is near the camera and the small housing shown farther drops down. You have to unfasten the safety wire that secures the threaded ring, black, and unscrew the ring to remove the bowl. Then you can reach back up and remove the filter for cleaning. Upon reassembly, you have to rethread and tie new safety wire to that ring.

The Aerolab one is 113 grams heavier, but I finally decided that's a good trade-off for the easier servicing.

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Here's the aft bottom skin with all the clecos in. I back-drilled through the added bulkheads, through the new shims, and through the skin.

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The F-325 tailcone skin that goes on ahead of this aft bottom skin isn't bent properly, besides being a bit short. Fortunately, since it's .025, I think I can wrestle it into place, even though it's bigger (but not heavier) than I am.

d5dt0.jpg


It's misbent on the forward end as well, but this isn't as obvious. Same problem, the bends are too far apart. There, it's trivial.

I used some straps while trimming the forward end. It's apparent that I'll need to use more tooling to force it to maintain the correct shape.

2ylkbie.jpg


Here's a photo of one of the methods I used to increase the bend. This only works near the edge, as the 1" x 2" x .120" aluminum tube (available from Wick's Aircraft, 6061-T6) needs a flat spot. Bending it by hand is too localized; use a stick or something to distribute the bend, and work down the length as needed. It's likely that the whole length won't need tweaking.

2ztksc1.jpg


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

Dave
 
With the long F-325 tailcone belly skin in place, I started strapping it down. It was quickly clear that I'd have to either make a set of Howe Fittings or figure something else out. Here's a first pass at the F-306 bulkhead straps.

b4uo7p.jpg


One thing that was necessary to continue was to get the tailspring mount back so that I could cleco the aft tailcone belly skin in place. Here it is, nicely cadmium plated. The plating was because this thing is exposed and difficult to remove (impossible, I think) and I didn't want corrosion problems.

20qj0ut.jpg


After strapping down this long belly skin I realized that the tailcone bulkheads were warping under the strap's tension. So that's why other people have made wooden bulkhead stiffeners! After removing the skin yet again, I made this set and have to apologize for the crudeness of the woodwork - especially compared to some of my other woodwork. Crude it is, and functional, too. Functional wins. The stiffeners are screwed to tooling holes I drilled in the bulkheads using #6 x 5/8" wood screws that I had on hand, and some #6 AN960 washers that I'm borrowing from future use.

156zii9.jpg


The F-306 stiffener can't extend the full height of the bulkhead since the jig's in the way, but I'll eventually need to have it do so.

One that was installed, I strapped down the skin again using this arrangement. Note that it's slightly different than the earlier set-up. It works and that's about all I can say for it.

2hi18up.jpg


And after some work, I have a lot of clecos installed. Working by myself, I found myself drilling a couple holes, getting up and installing two clecos, kneeling back down and drilling two more. It was slow-going. At one point, three consecutive holes needed three drills, one a 90 degree drill, one with a jobber's length bit, and one with a 12" bit, all one after the other.

r2l06c.jpg


The aft-most bay remains undrilled pending the next stage of the job. And I can see that I'll probably need to shim the F-306 bulkhead bottom flange, too. The next one aft, F-308, already has a shim and seems fair.

The photos are also hosted here, here, here, here, and need I say, here.

Dave
 
Dave's RV-3B Progress

Great progress Dave! I know it can be slow going without a helper to cleco as you go; but you're still getting it done!

Doug

RV-3A sold
RV-9A Mazda 13B (FWF)
 
Have just read this thread, man you sure have patients there ! Well done. I'd prefer to fly, don't think I'd have have the tenacity you have to do a full build
Shall watch this thread with interest from now on, good work, keep at it:)
 
Adding a Trio of Stiffeners

Thanks, both of you, for the comments.

I've got a very good certified airplane to fly so that's taken care of. I can fly or build as I choose on any particular day.

The RV-3 is the first of the RVs and both the kit and the plans are a bit behind current kit standards. The plans contain gaps and a bit of contradictory information, and the kit, since there isn't a reliable 3D CAD model to define it, is a bit spotty. Here and there some pieces don't fit well or they aren't formed as they could be. The majority of the kit is perfectly fine though.

One big difference is that the holes are missing. On a good, late kit, they are almost final size and in precisely the right place. On the RV-3 they simply aren't there until the builder drills them.

I suspect that the RV-4 is very similar in kit quality, although I do suspect that it's a bit better, since so many have been built. At any rate, the user base is larger. One reason for choosing to build an RV-3 was to have the fun of tackling these issues.

If you built one of the double-digit RV kits, I think you'd find that much of the work I get to do simply doesn't exist.

I'm adding three stiffeners to the tailcone belly skin, using Van's J-channels. These stiffeners aren't in the plans and frankly, you don't need them. I'm using them mostly to keep this skin fair, since the overall structure isn't necessarily fair and, I confess, I got a couple small bumps in the skin as I was trying to form it.

One by one, I'm gluing the three stiffeners to the skin. They'll get riveted, too. Here's the first one all taped up before gluing.

ih8ax3.jpg


For surface-fairness, I'm including a bit of exoskeleton structure so there won't be any surprises, like large shallow areas where the clecos were.

ei3ts3.jpg


Here is it with the glue still wet and the tape still on. The tape came off moments later. In the photo it was not pressed down over the flange because it would have then been hard to grab to remove.

6zrgur.jpg


Since then, I removed all the clecos and replaced them with fresh ones, just to prevent inadvertently glueing the clecos in. This probably wasn't necessary since I oil the tangs on each cleco before inserting them, and operate the cleco a few times to ensure that the oil spreads evenly over the surfaces. This works pretty well to keep them from getting glued in, and when I removed them, the excess epoxy came right off.

The remaining two are now glued on.

30k7pc2.jpg


And finally, using Sam Ritchie's long back riveting plate (he and his wife are building an RV-10), I back-riveted the stiffeners.

30kqels.jpg


The site that I've been using for alternate photo-hosting is closing. The primary site remains open and hopefully, the photos will remain visible. The result is that today I've got no way to post back-up links to the photos. Any suggestions?

Dave
 
With the stiffeners glued and riveted to the tailcone belly skin, I clecoed it to the bulkheads. In spite of my efforts, the bulkheads pulled the skin inward a bit. Never as much as 1/4" but at about 1/8" in more than one place, these skin depressions were, I've got to say it, depressing.

Can't have that.

There were only three options available that I could see.

1. I could shim the skin.

2. I could cut the errant flanges off the bulkheads and rivet new ones on.

3. I could model the tailcone in Solidworks and use that to fabricate new bulkheads.

Option #1 didn't appeal because of the thickness of the shims that would be needed.

Option #3 didn't appeal because of the time involved. One of my goals here is to have a building project, not an engineering project.

That left option #2. The plans, in the form of the SK drawings, provided some encouragement. Here's "SK-44 Blkhd Flange Replacement."

35mnsdg.jpg


You might be wondering why the bulkhead depressions occurred at all. I'd attempted to adjust for that during the bulkhead alignment and assembly. It turns out that my tailcone belly skin, if you look at it with a straight edge, fore to aft, is slightly convex. I don't know if it was made that way or if, while I was rebending it, I managed to do that all by myself. Doesn't matter, that's how it is now.

I cut off the bottom flanges of these parts:

Baggage ribs,
F-306 baggage bulkhead,
F-308 intermediate bulkhead.

And then spent time time fabricating new flanges. Locating the holes was easy enough: use magnets to hold the flanges against the skin, and more magnets to hold them against the bulkhead or rib. Drill through the skin and the flanges and then cleco to the skin. Mark, remove and drill the flange holes for the bulkhead, then reassemble the flanges to the skin. Back drill through the bulkhead or ribs.

This let the skin float as needed for fairness. Fairness having more to do with smooth flowing lines than justice, in this case.

This is the F-308 bulkhead with its new flange, plus the aft end of a couple of the J-channels that I added. You can see that some rebending or shimming will still be needed at the sides.

2psfz9v.jpg


And here are the F-306 flanges that I replaced. It's hard to see, but one of the baggage floor rib flanges is clamped to the rib and clecoed to the skin.

The most time-consuming part of these was rounding the tabs. My 12" disk sander was of no use for this, so I did it with files. I might buy a 1" belt sander, which ought to work.

I'd purchased a few F-803CPP tabbed angles from Van's, with this job in mind, but its flanges were too short for this.

jajbcg.jpg


As far as I've gotten so far, from the outside, with one bulkhead rib flange to complete and one more to fabricate - finally, no low spots:

9i614y.jpg


The bar in the middle is some 6061-T6 rectangular tube, 1" x 2" x 1/8" wall x 7' long. This is left over from a different project, and has proven to be an ideal tool with the RV-3B. I've used it in several places as a straight edge and as something to clamp to. I got it from Wick's Aircraft.

The milk cartons are filled with small pieces of scrap metal and well-taped to preclude rupture. Simple weights, soft sides.

I've changed my back-up photo hosting to www.halie.com, run by VAF member Bill Kervaski. Thanks, Bill, for hosting this.

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

Dave
 
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In order to cleco the new left hand baggage rib flange, I removed the tailcone belly skin for access. Here are the new bulkhead flanges that I've got clecoed on.

2db00wn.jpg


This provided me a timely opportunity to check the rig of the fuselage. I checked

Firewall, for twist and level,
Spar bulkhead for twist,
Rear spar bulkhead for twist,
Top longerons for twist,
Rear deck for twist.

There were three areas that were not 0.0 degrees. These were 0.1 degrees off, and I readjusted all of them.

Since the tailcone belly skin is already drilled, I needed to locate the holes and the flanges with respect to each other. I planned to back-drill down through the existing skin holes into the flanges. How to know when the flanges were in position? I marked the acceptable extent of the centerlines on the flanges. Holding the flange in position underneath the upside-down skin with magnets, it was easy to see when the flange was located correctly.

fny3go.jpg


It takes some prep work to make the skin and the flange ready to bond. I'd finally gotten the parts ready for masking at this point. They are abraded, dimpled and the exoskeleton is match-drilled. The exoskeleton is a length of 1 1/2 x 1/8 angle which I got for this purpose some time ago, and I only have one. So I'm working on just one of the flanges at a time. (Later I learned that 3/4 x 1/16 is sufficient for the exoskeleton, but this is what I'm using at this stage).

246w0e9.jpg


Finally, the baggage rib is bonded on with clecos holding it all together.

311s9iw.jpg


With that tying those parts up for now, I looked around for the next thing. The next thing was getting ready for a small tool out at the hangar, so I made those parts. No photos at this time, sorry.

Then I clamped the right hand side skin to the tailcone. Here it is with an outside view, where the clamps are. The blue skin to the left is the left-hand skin, waiting for its turn.

mszmn8.jpg


And here it is on the inside, looking through the fuselage - a limited-time opportunity.

9a8cpw.jpg


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

Dave
 
Since I'd removed the bottom flanges on the F-306 and F-308 bulkheads and replaced them, I decided to glue them to the belly skin. Here the glue is setting up out of sight and I've got some .063 x 1" aluminum strip as the exoskeleton. The blue film works okay as a release, but I wax the exoskeleton for additional assurance - combined with the film, these came off easily. I kept the skin clecoed to the frame until I was certain that the glue had cured. Here is what it looks like from the outside.

6ny44n.jpg


The right tailcone side is clecoed on, last week's work.

2i8b2ox.jpg


Then I drilled and clecoed the left side today.

111s2us.jpg


Every single one of my Wedgeloc clecos are in use right now. But it doesn't need all the holes filled now that I'm done drilling. I've got a couple buckets full of the other-brand narrower clecos and I used these on the aft-most belly skin. These can be identified by the lighter "buttons" compared to the darker Wedgelocs. Although the buttons are different shades, it's still easy to mix them up, so I try to avoid using both together. Just so that you know, the Wedgeloc ones hold more securely in dimpled holes, so they are preferred. Plus they're slightly fatter so they provide better positioning.

After clecoing on the bottom two tailcone skins and the right side skin, I've got this.

2dl9jq.jpg



r9oe1w.jpg


Of course it gets disassembled again tomorrow.

Before clecoing on the right side skin, which I did just for the photo, I'd measured, made and glued on the shims that I needed on the aft two double bulkheads. It appears as if the left side is following suit - the skin appears quite fair except that the flanges of F-310 and F-311 need shims.

On the right side, the flanges needed -

.063, forward flange of F-310,
.040, aft flange of F-310,
.032, forward flange of F-311,
And no shims at all for aft flange of F-311.

Remember that I doubled both these bulkheads. According to the plans and the kit contents, there was only one bulkhead intended in each location. Here are the shims after epoxying while still clamped.

2il21qe.jpg


It was a bit difficult to figure out how to drill the skin at the aft flange of the aft bulkhead, the F-311. The flange angle there is more than 90 degrees and the flanges are close together, so I couldn't backdrill with a jobber bit, a 6" or 12" bit or my angle drill. There just flat wasn't room. So I aimed a 12" drill through the existing holes on the opposite side and that was adequate. Sorry for the blurry photo.

2zjfk04.jpg


The images are also posted on Postimage.org in case TinyPic.com, my primary hosting, ever goes down. This is my first time using Postimage.org.

https://postimg.org/image/hgm04g8sp/
https://postimg.org/image/sybeumjdp/
https://postimg.org/image/84vbhr0fn/
https://postimg.org/image/wpw9bh7jj/
https://postimg.org/image/aqwlmcx8r/
https://postimg.org/image/shx0tkp4p/
https://postimg.org/image/mk4jq70qr/

Postimage was relatively easy to use, free, no ads, and the program opened a new window for each image, so it's easy to refer to them. There are nine types of link provided, but none of them use the HTML code beginning "
" which is used to make them visible on VAF. No problem here, I don't want them visible right now - just available in case the visible ones disappear. Also, I'm giving the links directly here rather than using my usual "here" just out of pure laziness.

Dave
 
Should have expected this....

As many of us know, the Wedgeloc brand of clecoes hold better in the #40 dimples than most other brands. I have two full buckets of other brand #40 clecoes, but only a small number of the Wedgeloc brand ones. Since these are wider, they provide better positioning even in the absence of dimples, and I ran out, with the two side skins and the belly skins clecoed to the tailcone.

Today I broke down and ordered more.

Dave
 
Looking good Dave, you should end up with nice fuselage skins. I also have used 12" drill bits, they can be "bowed" through gloved fingers to drill around obstacles as well.

My project is covered in fiberglass / micro dust at the moment, the skirts have been a learning curve... pretty much done thankfully.

Cheers,
Russell
 
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Looking good Dave, you should end up with nice fuselage skins. I also have used 12" drill bits, they can be "bowed" through gloved fingers to drill around obstacles as well.

My project is covered in fiberglass / micro dust at the moment, the skirts have been a learning curve... pretty much done thankfully.

Cheers,
Russell

x43y14.jpg
11ifggp.jpg
[/IMG]

Russ,
Nice work!
 
Please, as this is a blog about my own construction, let's keep the comments on-topic.

While I don't actually mind brief postings with photos of other RV-3s from time to time, they ought to relate to the area that I'm working on at the time, rather than parts that I won't get to for a while. And comments about those aircraft should be sent to the poster, rather than here.

Thanks very much,
Dave
 
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Here's the right hand tailcone side skin with a J-channel glued on. The J-channel stiffener, or for that matter, any stiffener there, is not in the plans. It goes between the F-308 and the F-309 bulkheads.

vBS3GIu.jpg


Then I glued the one on the left tailcone side skin, too.

xs5joIq.jpg


I've been told that it's easier to install the small F-307 sub-bulkhead now, rather than after the fuselage is right side up. Three-fourths of the way through the process, I remain skeptical. But now that I'm this far, I won't have the option of doing it later, so I'll never know for sure.

The bulkhead fits about like the ones aft fit: the shoulders aren't too bad but the bottom flange has to come off. Oh, yeah, and that's not all -- it's supposed to be 5" aft of the baggage bulkhead, measured web to web, and it had to go farther aft. While I don't expect any serious impact with the elevator control system, these skin flanges do interfere with those added J-stiffeners that I installed on the belly skin. At 5" it would have been fine, and if I'd made the stiffeners shorter, that would have been fine, too.

Here's the F-307 with the cut-out but otherwise stock. I figured out what the cut-out is for - I think it's to get the elevator pushrod in after assembly.

gkFNkdL.jpg


After cutting off the bottom flange, I made some new ones.

YJhYS8m.jpg


Those stiffeners? Uh huh, they interfere with the new flanges, too. This is taken looking forward from aft of the F-307.

9t9wqab.jpg


At this time, that situation is being worked on.

Here's a look at the sub-bulkhead now though, looking up from the floor (or is that down into the fuselage? It gets confusing...).

DLBObS0.jpg


Earlier today I saw that the right side of the F-306 baggage bulkhead, below the middle longeron, needs a shim. Hadn't noticed that earlier but there's no avoiding it. The light was different and that helped. I added it to my list of 17 tailcone skin things to do in the near-term. About a third of these are gluing things on -- it definitely adds to the time it takes to build this plane.

These viewable photos are hosted on Imgur.com, instead of the previous TinyPic.com. Imgur, which I'm trying out, is easier and quicker to use. Both are free. Please let me know if you can't see these, and if so, please try the following back-up ones.

Here are the alternatively-hosted photos. These are now hosted by Postimage.com, which I'm trying out. It also is fast, free and easy.

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

Thanks for following this blog.

Dave
 
8/18/17

The F-307 partial bulkhead's flanges are getting prepped for gluing. The idea is to glue and rivet them to the skin and then later rivet them to the bulkhead.

qHFF0Pa.jpg


Next, they're glued on. The bulkhead is in place along with the wooden bar to hold everything in alignment. The tape hasn't been removed yet.

NeCcSdj.jpg


Next, moving aft to the access plates for the elevator pushrod attachment, here's a draft of the layout I made. The width was an issue since the doubled bulkheads have flanges pointing at each other, restricting the width to less than the plans called for. Too late, I realized that if I'd done it right, I could have stuck nutplates on those flanges. Now, though, they have flutes too close together and the nutplates don't fit in between them. So it took some figuring. I made it higher for better access and since this opening takes a lot of the metal that is between the F-310 and F-311 bulkheads, I used two screws per side to share some load.

rCroctZ.jpg


This is my plan for the doubler at the nutplates. I'm allowing 2D edge distance, of course, and .2" overlap between the cover and the doubler.

yaQ0HPo.jpg


And the first side is cut-out. Note that unlike the draft, there are two nutplate positions on the bottom.

mNDyG00.jpg


And then I cut out the second side and did some trimming. I'm installing an access panel on both sides.

H2wgEDK.jpg


One of the access plates is made. It fits better than it looks in this photo.

fjiToLH.jpg


Now that you have an idea what I'm doing with my plane, let's take a look at the plans:

62ha7RF.jpg


The plans only has the access hole on the left side. I'm putting one on both.

My version is yet another consequence of deviating from the plans. Changes have ramifications.

This airplane will have steam gauges. Here they are, and yes, this is all of them. I'm only installing the basics.

XXyUaEG.jpg


These will be augmented by one of those pretty newfangled electric things someday when I'm installing systems.

If the primary photo-hosting site, www.postimage.com, ever goes belly up, these photos are also hosted at www.imgur.com and might remain visible: here, here, here, here, here, here, here,
here, and here.

Dave
 
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I would be concerned about how much material you have removed in the side skins to make your access openings, especially since you removed it all the way to the top. On my project I made the access hole square, only on one side and left an inch of side skin at the top.
 
I would be concerned about how much material you have removed in the side skins to make your access openings, especially since you removed it all the way to the top. On my project I made the access hole square, only on one side and left an inch of side skin at the top.


If there is a longeron there that bridges the gap it should be fine.
 
The King

I've been doing a bunch of small boring things like trimming, countersinking, priming and deburring. I finished making the access hatch covers and doublers but haven't riveted any of that together yet.

Both tailcone belly skins are ready to glue on.

I found that the only tool that would get in to the top longeron where the jig interferes is a flexible drill extension with a threaded end. I used a 3/8" countersink bit that wasn't in a cage for this.

One night I was countersinking and the radio played some of The King's songs. His songs move. I was moving too, right along with the music. Gotta say that Elvis has that title for a reason.

The bit of red electrical tape is something I use as a marker. I'll frequently countersink a bunch of holes and then measure them to make sure they're deep enough, with the tape keeping me from getting lost - one countersink an a longeron looks much like the one next to it. Here, there wasn't an issue but I used it anyway.

CS_Longerons_S.jpg


Trimming the tailcone side skins left me with some good quality squigglies. These are the kerf from the nibbling tool. Too bad that there's no use for these.

Squigglies_S.jpg


The aft bottom bay is a bit difficult to get into. Here's a look.

In the background, we're looking up and can see the ceiling. I had the bare structure sprayed with foam insulation, 6" of it, and it's very effective. Before that, I had ceiling outlets added for both the radiant heaters and for ceiling lights. The standard double socket in the top center is for the lights, while the single socket to the top right is for a heater. This gives me a lot of flexibility as to where I put these things.

Aft_Bay_S.jpg


When the taped skin is back on, it'll be hard to remove the tape after gluing. I left fold-unders at one end of every piece of tape, hoping that I can get it out.

Aft_Skin_Masking_S.jpg


The skin is .040 and is too thick to dimple with my equipment, so I'm going to have to countersink the skin.

These photos can also be seen here, here, here, and here.

Dave
 
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Finally got the aft-most belly skin glued on. This is the one right in front of the rudder. On the RV-3B it's .040 thick and in previous posts you've seen it in progress at various stages.

I used West System's G/flex epoxy, the pre-thickened variant. This is just thick enough that it doesn't run. It's too thick to laminate with, being intended strictly as an adhesive. It's a relatively tough, flexible epoxy but that's relative to stiffer varieties. I chose this on the basis of good results reported by two very experienced and knowledgeable friends. 3M's 2216 adhesive is another that would work well, and perhaps better.

This particular skin was small enough that I could manage it all myself, within the 45 minute pot life. I think that for anything larger than this I'd need assistance.

oO6.jpg


In the photo, I've got the longer tailcone belly skin clecoed on just ahead of it, to its left.

This aft-most belly skin still needs rivets. More than that, it needs countersinking too. I decided to wait on that until after gluing because even for .040, there's not much cylindrical bore remaining after countersinking, and I wanted the clecos that were in place while the glue set up to give good alignment.

The photo is also here, in case it's not visible above.

Dave
 
My mentor suggested that I install supports for a future tailcone work platform now, since this would be a lot harder after the tailcone skins are on. Here are the supports at the two aft-most bulkheads.

This is for the F-309 bulkhead, as far aft as the platform will go. Those clecos are simply making sure that the skin, now glued on, stays good until I can get some rivets on it.

7x8kAc7.jpg


And this one is for the F-308 bulkhead.

mFCfvT9.jpg


Then for some reason I decided that this was the right time to make the transponder mount. Why now? Because it gets mounted on the right side of the tailcone just aft of the baggage compartment, and that side was clecoed on at the moment, and also because I had a transponder on hand just for this. It's been suggested that I make a mock-up of the transponder (a very good suggestion, by the way) and use that for fitting but I was able to obtain an actual one and being lazy, used that instead.

Why there? It's not far from a convenient place to hang the eventual antenna and while it's out of the way of the snug cockpit, it's not buried deep in the tailcone. I should have reasonable access to it in this location.

Here goes.

This is the basic mount clecoed in place. I'll probably use LP4 blind rivets when this finally goes on, sometime after the skin is riveted and the canoe is flipped, hard as it is at the moment to imagine those events.

HQT0ThS.jpg


Then I finished up the mount, rounding some corners, final-drilling and adding a lightening hole.

es5tUdy.jpg


Just to prove that it all hangs together, I temporarily installed the transponder on the mount.

kiFoThR.jpg


And whew, it fits.

Moving right along, the right hand tailcone side skin's aft inspection hatch doubler needed to be glued on. First it needed to have the nutplates installed and the holes dimpled. I hadn't gotten to the dimples yet when this got taken, but I did do that later.

m3TC0Xv.jpg


These photos are also hanging out here, here, here, here, here and here.

Dave
 
Trimmed some edges the other day to save some weight. I saved about 40 grams, almost 1 1/2 ounces, and it only took me four hours. Anyone can make a bargain like that if they want it badly enough. To honor the effort and keep blood off things, I put two timely bandages on my fingers.

One unexpected workshop observation is that I seem to need a number of different kinds or sizes or colors of tape. They take an entire shop drawer. Who'd have expected that?

The aft-most belly skin has been glued down for a while now. I took the time to rivet it to the flanges.

After that, I went back to the rear spar carry-though, which still isn't riveted. Back in post #209, you can see the rear spar locating fixture I made when the wings were on the stand. It contained a conceptual error that's worth pointing out and you might already know what that is -- the fixture goes inboard of the inboard ribs, and on the fuselage, well, the fuselage is there blocking that location; the fixture can't go to the right place. What to do?

Spar_Fixture_S.jpg


Here's what I did.

1. I got some 1" square aluminum tubes and match-drilled some of the 3/8" spar bolt holes through them. They are 18" long and when pinned into the fuselage spar bulkhead, protrude outboard far enough to work off of them. The top face of the top tube on each side was matched to the top face of the spar, since that was a location point for the fixtures.

2. Since the spar gap in the bulkhead is 1 1/16" wide, I glued some 1/16" model airplane plywood to these bars so that on the front face, the plywood fills the gap between the tubes and the bulkhead. 1/16" aluminum would have worked as well.

3. With the tubes pinned in place, I now had an aft spar simulator face for the fixtures to register against. This located them vertically, fore/aft, in pitch and in roll. The construction of them located them in yaw. What was in error was that fact that they are located outboard of where they were when they were built.

4. I removed the rear spar carry-through and marked a horizontal centerline for the future rivets and the proper length according to the plans. Originally, I'd left the length untrimmed but now I can see that this dimension is reasonably close. It'll get trimmed in length when I first mount the wings.

5. Knowing how far outboard the fixture is now compared to when I built it, I was able to position the carry-through in height so that it should be correct. The main spar is at a 3.5 degree dihedral angle and the fixture is based on that, while the rear spar carry-through is horizontal. This means that the spanwise positioning error puts the rear spar carry-through locating angle that's on the fixture slightly above where it ought to be: the distance is off thusly:

Error = Spanwise error * tangent (3.5 deg.)

So I think that I was able to get reasonably close, as the height error is under 1/16" per inch spanwise position error, and that spanwise error was less than 3/8".

The wings are presently stored out at the airport, half an hour away, and this took a few trips to get nailed down.

The rear spar carry-through is shown on the plans as being held on with a single row of rivets. Not shown are the seat-belt mounts, which bolt through it and the curved pieces at the aft side of the rear spar bulkhead that attach the long belly skin at its shoulders. I need to allow for these, too.

After some more messing around, mostly with getting the rivet spacing so that they would go where they needed to, I riveted the rear spar carry-through to the seat bulkhead. You can see the empty outboard holes for the seat belt anchors.

Rear_Spar_Carrythrough_Rivets_S.jpg


Then I drilled the exoskeleton angles to the lower longerons for the eventual gluing of the belly skin.


If you haven't seen the two photos in this post, please try
here and here.

Dave
 
Today's job was to glue the long belly skin to the fuselage. I'm using G/Flex epoxy, the thickened variety, which has a 45 minute pot life. A dry run showed that it took me 1/2 an hour to get the skin and the hardware all set up, so I knew I needed some assistance. Dave Dooley stopped by to lend a hand.

The skin and substructure was ready to go, with tape on and the cleco tips oiled.

I mixed up a couple tubs of the glue and we started buttering it on. It went to the perimeter and the shoulders of the bulkheads. Then we lifted the skin into place and with the exoskeleton, started clecoing it all together. We only needed one cleco every four rivet holes but we added a few more, here and there, for assurance.

Then we wiped the epoxy off the tips of the clecos and pulled off some of the tape and made fillets at the edges of the joints. Dave left and I took this not-so-great photo.

Long_Belly_Skin_Glued_1_S.jpg


After a couple hours I replaced all the clecos with fresh one that I hadn't oiled. The glue had cured enough that it wasn't going to stick to the new ones, and I really didn't want the original ones to get glued into the airplane.

Later still, I removed the exoskeleton and the remaining tape. With the exoskeleton off, the sides of the skin stayed stuck down, a very good sign indeed. I replaced most of the clecos for security anyway since the epoxy hasn't fully cured.

If you can't see the photo above, please try here.

This was an uncommonly productive day. I even had time to start a loaf of sourdough bread for rising and baking tomorrow.

Dave
 
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Too strange. Just by chance, I made a loaf of rye bread today when I couldn't take any more priming and sanding.
Are all of the skins bonded and riveted on the RV3?
 
Bread's good, and compared to an airplane, it's almost like instant gratification.

I made a loaf of sourdough rye a couple days ago - good stuff. Funny that you made a rye loaf too.

The bonding is not to the plans. The RV-3B is a riveted airplane, and riveted only. My mentor is out of state and I went for a visit and was struck by the quality of the rivet lines, which were superior to those on most of the non-bonded airplanes I'd seen. He gave me his gluing process and I started gluing things together prior to riveting. At first I merely used it as a holding fixture, but as I got more confidence with it, I decided to try that aft-most belly skin. That went relatively well and I bonded and riveted some flanges and stiffeners onto this skin.

They came out the way I'd hoped and with considerable trepidation, I decided to go ahead and attempt to bond this skin on.

The overall bonding process takes a fair bit of additional time but it seems to me to be worth it. The initial look of this skin was favorable so I am currently planning to bond the long tailcone side skins on too. After that there's only the cockpit area skins and I'll decide about them when I get to them.

I did not bond the wing, tail or control surface skins. But if I were starting afresh, I believe that I would, especially as the difference is so clearly discernable. Worth noting is that I don't really need this airplane and have no plans to use it as much as I should. I'm mostly interested in it as a construction project and to keep from getting bored or intellectually lazy, and for that purpose, bonding is excellent. So for me, the bonding fits well into the project.

Would I recommend this to everyone? No, of course not. If you want a flying airplane in a realistic amount of time, skip this idea. The airplanes are entirely satisfactory if they are built to the plans.

Am I trying for a Lindy? Absolutely not. In fact, I have no plans to ever again go to Oshkosh at all. In any case, the wings are not nearly show quality. All I'm trying to do is indulge myself.

In that respect it's a bit like baking sourdough bread. It takes longer for somewhat better results, but it's not necessary.

Dave
 
Truth be told, almost every one of the planes being built is for self-indulgence. It's great that you take the time to share your experience with everyone else.

I can see several advantages to the bonding process. Wondering if you've considered some of the newer adhesives developed for the automotive industry. Most of the auto manufacturers are using adhesives in areas formerly welded; they're that good. It's allowed them to combine steel and aluminum in areas that would have been impossible to do before. Even the repair shops are replacing welds with glue.

Bought an ebook on fermentation a couple weeks back. Sourdough was one of the things that I've decided to try. Did it many years ago but failed to use it enough to keep it alive. Didn't have the discipline to devote to it.

Thanks again for your posts.
 
I'm trying not to reinvent things here. I'm using one of the two epoxies that are recommended by my mentor, who has tested it. The other is 3M's 2216. Another friend, in the marine industry, has also recommended G/flex for aluminum bonding.

While there are many glues, I don't know what the automotive industry uses or even what the glue companies recommend.

Dave
 
David,
Question, if you should ever have to replace a glued and riveted skin, how hard would it be to remove with the glue holding it?
 
Good question!

Probably quite difficult. Heat might help, I don't know. Or my glue prep might prove insufficient and the pieces might pop apart. I have no idea and repairability isn't one of my goals.

If the plane should need so much rebuilding that fuselage skins need to be replaced, I'll either hire a pro or part out the plane. But note that I'd take one of these approaches even if it wasn't bonded; I have no interest in that level of effort.

Dave
 
I truly do not wish to rain on anyone's parade, but I wonder if allowing the adhesive to cure before the parts are riveted together would prevent the parts from properly "nesting" together. I assume the force exerted by the clecoe's is not nearly as great as those exerted by driven rivets, therefore leaving a thin layer of adhesive that over time could breakdown?
 
Folks, if you spot a potential issue with this or any other aspect of the construction, please let me know. I'm only human and I do goof sometimes.

Thanks for commenting.

The parts are dry-fitted together before gluing to verify a close-fit joint; and the edges of the joints are not sealed to allow excess epoxy thereby come out. Which it does, and needs to be removed.

Post-cure inspection of assemblies made so far does not indicate that there's a problem of this nature.

Dave
 
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Before I could rivet the long belly skin, the side skins need to go on. The bottom of the belly skin was already riveted to the various stiffeners and bulkhead flanges, so the only remaining parts were at the ends and the bulkhead shoulders, and they can wait till I do the lower longeron and bulkhead riveting for the side skins.

The tape bumps roughly in the middle are folded-over tape, giving me aen easy place to grab on to for removing the tape. I now like 3M's model 33 electrical tape. I've tried blue painter's tape, which is harder to remove, and green painter's tape, which is fine if there's a wider area to tape but is slightly harder to remove. However the green painter's tape conforms down into the dimples better.

One of the steps to this gluing is to mask off the areas adjacent to where the glue goes and then do a dry fit check to verify that the tape is in the right place. At the upper left, you can see that I needed to adjust this a bit. The tape is slightly apart from the joint so that I can form the glue squeeze-out into a fillet there.

Skin_Taped_S.jpg


After a couple of intense days the left side skin was ready to install. I gathered up some friends and we began. About two hours later, we took these photos.

This is Dallice Tylee to the left and Dave Dooley to the right. They're both pilots; Dallice flies a Bonanza and Dave built a Xenos motorglider and also has a Swift.

Dallice_1_S.jpg


And here's me. I'm pretty happy - we didn't screw it up.

No_Fubars_-_Me_S.jpg


Don't know if you noticed but we were all wearing gray shirts and jeans, completely unplanned. It wasn't a uniform, this was junk clothing that we could get glue on. As it turned out, we didn't - we used up a bunch of blue gloves, though.

If you're using epoxy and need to remove some from something, ordinary cheap vinegar works fine if the glue hasn't set up. Wash in vinegar, wash in soap and water, dry, done.

The skin has the exoskeleton on. This acts something like a mold, ensuring a smooth, fair skin. As soon as the glue is thoroughly cured, that comes off. Here's the skin with the exoskeleton on.

LH_Skin_Exo_On_S.jpg


And again with the exoskeleton removed. There's still considerable clean-up to do at this point.

Exo_Off_LH_S.jpg


The photos can also be found here, here, here, here, and here.

Dave
 
After the gluing came the clean-up, and then the usual bunch of small things before anything major ever happens. Yesterday, though, Larry Larson came down from Estes Park, down to the valley, to help me rivet. You folks know him as Wirejock. His RV-7 is much higher build quality than my little RV-3B, so I was glad to have him over today.

We riveted the left side to the frame. We got all but the top longeron, of course, and we even managed to include the bulkhead shoulder rivets in between the lower longeron and those replacement bulkhead flanges that you saw earlier. So it was a good day.

He even brought treats. He bakes bread and brought me some really delicious sourdough he'd made. Yummy!

When we weren't talking about bread, he riveted and I bucked.

Larry_LH_Side_Skin_S.jpg


Some times the fuselage was tight and there wasn't much distance between the fuselage and the jig's side, and I had to work through the still-open right hand side. I suppose that I was doing it by feel since my eyes were wide shut here. It'll get harder when the right hand skin is on.

Riveting_LH_Side_Skin_S.jpg


There aren't any photos showing me wholly inside the fuselage yet, but the various aches and sore spots assure me that I was really there.

We started with me inside the fuselage using a back-rivet set, and Larry outside using a fat back-riveting bucking bar. That went fine for a while and then I ruined several rivets in a row, and switched so that Larry used a rivet set outside while I bucked inside. These generally gave better shop heads. The factory heads outside were uniformly good, but of course the skin had been glued on so that its position was fixed. If you're gluing the skin, it doesn't matter which you use - use whatever technique works best for you. If you're not gluing, my experience yesterday doesn't apply.

If these photos ever disappear, they might be available here or here.

Dave
 
Ruveting fun

You're too kind and too critical of your build. It's a beautiful 3B.
I recommend everyone spend some time helping another. It is so much fun and a great way to practice perishable riveting skills. In my case it was an opportunity to give back some of what my Mentor, Dave, is so graciously given me. He even made an awesome sourdough rye for us to bring back home.
 
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.

Riveted_Bulkhead_Flanges_S.jpg


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.

Dwg_24_Excerpt.jpg


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.

Back_Cover_2017.jpg


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:

https://imgur.com/tGyq3T1
https://i.imgur.com/L4zn2Ve.jpg
https://i.imgur.com/6EoEz5U.jpg

Dave
 
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