Stjohn's RV-7

1 hour
This morning, I countersunk the F-631A channels. No pics, since this isn’t a very interesting thing, but the process was pretty cool. I set everything up assembly-line style, by putting the countersink cage in the floor-standing drill press and building a fence with a pilot hole out of wood. I gave each hole a swipe with the Boelube stick and was able to knock out all 4 channels. Now I get to deburr the insides of the channels, prime them, and rivet them together. Then I have to figure out the whole attachment to the fuselage. That, friends and neighbors, is going to be interesting.
At some point, I WILL be able to paint the interior, but it looks like Terminator 4 is about to start stealing my weekends from me, so I might slow down on the plane for a bit, but not before I get the roll bar done.

1.5 hours
Not much cabin frame work. Mostly what I did was make the guest house bedroom ready for the influx of finish kit parts. Mike from Partain Transport dropped off the finish kit crate and we got it into the driveway, after a little game of aircraft Tetris in the trailer. My kit was buried under 3 RV-12 subkits and a partially completed RV8 which was on its way to Colorado along with a Super Cub wing. Tomorrow, Dave and I will pop the lid off the crate and put all the bits in the garage or the guest house. The crate itself will become part of a home improvemnent project I’ve been putting off for a long time.
What I actually got done on the cabin frame was to un-cleco the assembly, drill the aft attach bracket and deburr the upper and lower strips. Tomorrow I’ll set up some genius way to countersink the F-631A channels. Then if time permits, I’ll scrub them, rough them, and prime them.

4 hours.
Today was all about the roll bar. Last time, I had the F-631A channels clamped to the plywood, ready for drilling, and I got the F-631C plate drilled to the aft section. Mostly it was about measuring. Measuring to make sure there was edge distance on the channel as well as on the strip of .063 that holds the whole kaboodle together. This was a pretty timeiintensive process. The sequence is thus: Measure the line along which the holes go, mark where the holes go, clamp, drill, cleco. Dig:
Here’s the channels jigged up on the plywood. Remember, we measured this apparatus so that it, and the attach brackets are exactly as wide as the fuselage. At this point, the channels have been marked for drilling.

To mark the channels for the proper edge distance and hole spacing, I bagged a strip of .016 (or whatever the really thin stuff is) and marked out holes with the rivet fan, evenly spaced, a little less than an inch and a half, per plans. It flexed enough to fit the curve of the channels so I could mark off the hole spacing without having to measue each one. That would have been tedious in the extreme. I love the rivet fan.

At this point, I’ve just gotten to the curvature of the channel. This is where the inner strip really wants to pull away, so I’ve got c-clamps holding it tightly against the channel while I drill. I’m using the 90 degree angle drill for this, because it rocks for this kind of stuff.

Bottom aft channel is drilled and clecoed. I repeated the process with the upper strip. This let me fit the forward (top in this case) channels to the previously drilled strip. Then I clamped, drilled and clecoed. Easier than the aft channels, because this time the inner strips are held in place and in the correct shape already.

Of course, it helps if the assemblage is clamped flat to the workspace, so that’s what I did. At this point I’m just finishing the upper left quarter.

Once it’s done, it’s a surprisingly rigid structure, which is only going to become more so when riveted. The plans have you do solid rivets on the forward section and blind rivets on the aft. I can see why you have to use blind rivets on one part of it, you can’t reach in there to squeeze or buck with all channels in place. Not unless you’re a liquid metal T-1000, but if you were, you’d be hunting down an annoying kid who’s supposed to save the future instead of building an RV-7. Anyway, here is the roll bar, wearing pretty much my full complement of 1/8″ clecoes.

Tomorrow, while the girls are eating fondue and swooning at the Oscars (Dark Knight should have got the nom, Benjamin Button blows), I will be out in the shop countersinking each and every one of those holes for flush rivets.

3 hours.
Made the brackets attaching to F-631A, clamped the F-631A channels down, and did a whole lot more measuring than anything else.. I was able to commandeer the tabletop from Shelley’s potting table, which is actually just a piece of plywood left over from the bathroom project. It’s just a little bigger than the vertical dimension called out on the plans for the roll bar, so it was easy to get clamps along the top edge and almost halfway to the corner bends. The channels are cut to fit, but this was only after lots and I mean LOTS of measuring. The plans call out a width for the roll bar, but that’s not set in stone. The roll bar, plus the F-631 angle brackets, needs to be exactly as wide as the fuselage. The QB boys built a straight ship, it’s only about 1/32 wider than it’s supposed to be. Not only that, it will come into line when the skin is riveted down. I did leave about an extra 3/64 of an inch extra, because the outboard angle brackets will have to be contoured to match the curvature of the longerons after they’ve been fit and drilled. I got the F-631B straps cleco-clamped in, but the cleco-clamps don’t grip tightly enough, so I had to run to B&B Hardware for a bag of clamps. I got a bunch of little C-clamps, and a bunch of spring-loaded alligator-style clamps, which will hold the straps tightly against the channels while I drill them. I got the F-631D plates drilled, and the one for the aft channels drilled in and clecoed to the wood surface below. Then there was a lot more measuring. To have proper edge distance, the holes to attach the straps to the channel need to be 1/4″ from the edge of the channel. But of course, I didn’t mark that distance before clamping them down, so I had to do that, which took some time. Then I had to do the spacing for the holes. the only hole that has a distance specification is the one lowest on the channel, to keep the fastener clear of the angle bracket. Rather than calculate the distance for each hole, I got a thin 1/2″ strip of aluminum from one of the trim bundles (I’m pretty sure these are reinforcing strips for fiberglass emp tips), measured the specified distance, and spaced out holes from there with my rivet fan. This strip bent to fit the curvature of the channel, so I clamped it to the edge of the channel and transferred the hole marks along the 1/4″ line.
I need to be finished with this process by the weekend, because shelley’s going to want her potting table back.

.75 hours
Worked on the roll bar this morning. I radiused the inner bands so they fit nice in the F-631A channel, then trimmed the channel so the ends were exactly the dimensions called out on the plans. I’m expecting this thing to float around a little and stiffen up when the rivets go on, but I’m desperately trying to avoid the headaches experienced by so many other builders with regards to the fit with the skin, etc. The big angle brackets called out on DWG39 mount the roll bar to the fuse. I made those and after seeing how it works on dwg 40, it’s going to be…. interesting to get them totally flush with the skin on the outside. The thickness of the angle bracket also looks to be similar to that of canopy plexiglass. I get what they’re doing, but this is one of those things that would make lots of extra work and maybe a parts order if I screw up even slightly.

3 hours.
For real this time. Last time, I torqued down the AN4 bolts and found that the side-to-side motion of the stick was… resistive. as in, not “free and correct. After checking VAF, it seems that it’s a fairly common problem for the control column parts’ fit to suck. I just ground down the stick and the bushings and threw the column in a vise and bent the ears outward a little. Not a big deal, and by all reports, the right thing to do. Also, the usual solution is to ream out the tube welded to the stick, grind it and the brass bushing so they slip fit between the ears on the control column, which I did. It still didn’t work. I was still getting friction after the bolts were torqued down. So then I had a thought. What if the surface on the end of the bushing wasn’t ground perpendicular to the bushing? Would that not create a side-load and cause friction inside the tube rotating around the bushing? In a word, yeah.. It would. So how the frak do I make the end of the bushing square to the side? The answer seems obvious, but it escaped me for a bit: Chuck the bushing into the drill press, then lower it onto a file resting on the platform of the press. Bingo. perfectly flat bushing end. Sure enough I torqued it down and it move freely, just like it’s supposed to. These shots are of the stick moving the whole kaboodle back and forth without error:


And here’s the control column assembled:

Of course, i’m skipping the less than complimentary things I said while trying to get all the bolts and washers in before final torque and application of torque seal, most of which would get you fined if you said them on TV. But once that was done, it was time to move on to the roll bar, or ‘cabin frame’ as Van’s calls it. I got the aft cabin frame halves drilled for the access holes, then started on the F-631x angles, which will eventually hold the roll bar to the fuselage. I still have more work to do on these, but they’re getting there. Oh, and a shot for the FAA, just to show, yes, it’s me building this thing.

1.5 hours
Thought I was going to be done with the control column, but no, still had to remove more metal from the lightening holes of the seat ribs for clearance. Now it’s all good, and the control column is bolted in, torqued, and torque-sealed. So little appreciable effect for an hour and a half of work, but now it’s in and done. I still have to drill holes in the sticks for later switchgear, but they can come out easily. I had hoped to get going on the roll bar, but if I can finish this rigging task, then I can call it done until it’s time to actually bolt the wings on. I’ve also decided to get the trio autopilot servo and mounting kit, which i’ll put in the wing before I close it up, rather than under the seat floor in the most outboard bay. I’m saving that spot for the strobe kit, and the trim servo has to go somewhere as well. It’s going to start getting crowded in there soon. I still need to rig the rudder, so I’ll probably do that while i’ve got the tail on. I can pop the cable grommets out for painting.
Another thought about painting the interior: There’s not a lot to paint in there; aft seat floors, sides, armrests, and the forward part of the aft top skin. The rest are all detachable and will get painted separately. It’s a full weekend’s work, I think, painting all that stuff. I want to get the roll bar done before I paint, and ideally I’d like to have the finish kit so I can paint the canopy frame as well.
Not that it matters. A lot of this will have to wait until the weather gets better and I have some time. I just hate having too many irons in the fire at one time, especially with limited space.

1 hour.
I got home from work yesterday and my replacement VA-101 had arrived in the mail, so I decided to sort out the aft push tube and see if I couldn’t rig the elevators. Long story short, my theory was correct, and I was able to get more thread on the forward pushrod’s end bearings, but something was still kind of weird. I still could only move the elevator to one stop or the other, but not both. Adjusted for maximum clearance in full forward stick, the rod end bearing would bind on the control column when pulled all the way aft. When adjusted the other way, the control column would contact the insides of the lightening holes in the ribs before the elevators hit the stop. It didn’t really matter how much adjustment I did, one of those two situations would always occur. If you look at the seat ribs in the area of the control column, you can see there’s a definite cutout for the arc of the control column. I mentioned before that the control column’s fit sucked, most likely due to warpage during the welding process, or badly formed parts. I suspect this is also responsible for the few thousandths of aluminum making the stick rub on the ribs. This was compounded by the fact that the two center ribs, the ones wich have the access notches cut out, didn’t have all the metal removed that was supposed to be removed. Long story short, I was able to take off a couple thousanths of an inch from the lightening holes and the access notches to allow the column to move freely through its whole range. I have plenty of thread inside the rod end bearings, and the elevator now moves all the way to both stops unhindered. Just for kicks, I got the panel and subpanel assembly out of the loft and clecoed it into place on the fuselage. The stick doesn’t hit it and there will still be plenty of room once I install whatever stick grip I eventually choose.
And the best part? I sat in the hull, moved the stick back and forth, and watched the elevators go up and down in the reflection in the sliding glass door.